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Boost converters suffer from a bandwidth limitation caused by the right-half plane zero (RHPZ), which occurs in the control-to-output transfer function. In contrast, there are many applications that require superior dynamic behavior. Further, size and cost of boost converter systems can be minimized by reduced voltage deviations and fast transient responses in case of large signal load transients. The key idea of the proposed ΔV/Δt-intervention control concept is to adapt the controller output to its new steady state value immediately after a load transient by prediction from known parameters. The concept is implemented in a digital control circuit, consisting of an ASIC in a 110 nm-technology and a Xilinx Spartan-6 field programmable gate array (FPGA). In a boost converter with 3.5V input voltage, 6.3V output voltage, 1.2A load, and 500 kHz switching frequency, the output voltage deviations are 2.8x smaller, scaling down the output capacitor value by the same factor. The recovery times are 2.4x shorter in case of large signal load transients with the proposed concept. The control is widely applicable, as it supports constant switching frequencies and allows for duty cycle and inductor current limitations. It also shows various advantages compared to conventional control and to selected adaptive control concepts.
Externe Ladeinfrastruktur kann rechtskonform aus dem Stromnetz einer öffentlichen Liegenschaft versorgt werden. Bisher war die Vorgabe, die Versorgung über einen eigenen (neuen) Netzanschlusspunkt zu realisieren. Die hier vorgestellte Lösung ist ökologisch, wirtschaftlich und technisch deutlich günstiger und dient als Muster für die weitere Erschließung landeseigenen Parkraums in ganz Baden-Württemberg. Ein virtuelles Kraftwerk ermöglicht den gemeinschaftsdienlichen Betrieb.
This article proposes several modified quasi Z-source dc/dc boost converters. These can achieve soft-switching by using a clamp-switch network comprised of an active switch and a diode in parallel with a capacitor connected across one of the inductors of the Z-source network. In this way, ringing at the transistor switching node is mitigated, and the voltage at the turn-on of the transistor is reduced. Even a zero voltage switching (ZVS) of the main transistor is possible if the capacitor in the clamp-switch network is adequately chosen. The proposed circuit structure and operating mode are described and validated through simulations and measurements on a low-power prototype.
Der elektrische Wirkungsgrad stellt eines der wichtigsten Bewertungskriterien für BHKW dar, da über diese Größe ausgedrückt wird, wie viel des Wertproduktes „elektrische Energie“ bezogen auf die eingesetzte oder aufzuwendende Brennstoffenergie produziert werden kann. Ein hoher elektrischer Wirkungsgrad ist somit gleichbedeutend mit hohen Erlösen aus dem Verkauf der erzeugten elektrischen Energie und damit eine grundlegende Voraussetzung für einen wirtschaftlichen Betrieb eines BHKWs. Folglich sind die Hersteller von BHKW bestrebt, den elektrischen Wirkungsgrad ihrer Geräte kontinuierlich zu verbessern und nach oben zu treiben. Dieses Bemühen zeigt sich eindrucksvoll an der Entwicklung der mechanischen Effizienz von Gasmotoren der Firma GE Jenbacher. Während mit Motoren der Baureihe 6 im Leistungsbereich 1,8 – 4,4 MWel im Jahr 1988 eine mechanische Effizienz von 34% erreichbar war, liegt dieser Wert mittlerweile bei etwa 47,5%. Diese enorme Steigerung konnte im Wesentlichen durch eine Erhöhung des mittleren effektiven Zylinderarbeitsdrucks von etwa 10 bar im Jahr 1988 auf derzeit 24 bar erzielt werden. Dabei hilft der Magerbetrieb, der gleichzeitig ein Zurückdrängen der NOx-Emissionen bewirkt, die Klopfgrenze zu höheren Drücken hin zu verschieben. Eine sichere Zündung des Gas-Luft-Gemisches wird durch die Vorkammerzündung erreicht.
Willingness-to-pay for alternative fuel vehicle characteristics : a stated choice study for Germany
(2016)
In the light of European energy efficiency and clean air regulations, as well as an ambitious electric mobility goal of the German government, we examine consumer preferences for alternative fuel vehicles (AFVs) based on a Germany-wide discrete choice experiment among 711 potential car buyers. We estimate consumers’ willingness to-pay and compensating variation (CV) for improvements in vehicle attributes, also taking taste differences in the population into account by applying a latent class model with 6 distinct consumer segments. Our results indicate that about 1/3 of the consumers are oriented towards at least one AFV option, with almost half of them being AFV-affine, showing a high probability of choosing AFVs despite their current shortcomings. Our results suggest that German car buyers’ willingness-to-pay for improvements of the various vehicle attributes varies considerably across consumer groups and that the vehicle features have to meet some minimum requirements for considering AFVs. The CV values show that decision-makers in the administration and industry should focus on the most promising consumer group of ‘AFV aficionados’ and their needs. It also shows that some vehicle attribute improvements could increase the demand for AFVs cost-effectively, and that consumers would accept surcharges for some vehicle attributes at a level which could enable their private provision and economic operation (e.g. fast-charging infrastructure). Improvement of other attributes will need governmental subsidies to compensate for insufficient consumer valuation (e.g. battery capacity).
”I have never seen one who loves virtue as much as he loves beauty,” Confucius once said. If beauty is more important as goodness, it becomes clear why people invest so much effort in their first impression. The aesthetic of faces has many aspects and there is a strong correlation to all characteristics of humans, like age and gender. Often, research on aesthetics by social and ethic scientists lacks sufficient labelled data and the support of machine vision tools. In this position paper we propose the Aesthetic-Faces dataset, containing training data which is labelled by Chinese and German annotators. As a combination of three image subsets, the AF-dataset consists of European, Asian and African people. The research communities in machine learning, aesthetics and social ethics can benefit from our dataset and our toolbox. The toolbox provides many functions for machine learning with state-of-the-art CNNs and an Extreme-Gradient-Boosting regressor, but also 3D Morphable Model technolo gies for face shape evaluation and we discuss how to train an aesthetic estimator considering culture and ethics.
Bei der Zerspanung mit geometrisch definierter Schneide (z.B. Drehen, Fräsen, Bohren, Reiben, Sägen, Hobeln, Stoßen, Räumen) werden Zerspanwerkzeuge mit einer definierten Schneidengeometrie verwendet. Die Werte der einzelnen geometrischen Maße basieren auf Richt- und Erfahrungswerten. Die Definition der einzelnen Geometriemerkmale (z.B. Winkel) sind in DIN 6581 enthalten. In den letzten Jahren wurden zur Ermittlung des Prozessverhaltens unterschiedlicher Geometrieparameter Forschungsprojekte durchgeführt, die die Einflüsse der Schneidengestaltung untersuchen (z.B. Zabel 2010). Die Schneidengeometrie wird in der Regel mit den Verfahren Schleifen, Erodieren oder Laserbearbeitung erzeugt. Die Werkzeuge werden auf Universal- oder Spezial(werkzeugschleif)maschinen hergestellt und aufbereitet. Die Ausstattung und der Automatisierungsgrad richtet sich nach den zu bearbeitenden Merkmalen der Werkzeuge und deren Häufigkeit.
Die Additive Fertigung bietet großes Potenzial zur Erschließung neuer, flexibler und innovativer Fertigungsprozesse mit kurzen Durchlaufzeiten. Erhöhte Komplexität und die Integration von Funktionen in Bauteile wird gefördert. Zur Steigerung der Konkurrenzfähigkeit und weiteren Ausweitung des Einsatzgebietes sind automatisierte Fertigungsschritte nach dem Bauprozess erforderlich. Werkzeugmaschinen spielen auch in der Prozesskette der Additiven Fertigung eine zentrale Rolle bei der Erzeugung von genauen Funktionsflächen. Dabei ist evtl. eine andere Auslegung aufgrund reduzierter Zerspanvolumen und geringeren Flächen möglich.
Today the optimization of metal forming processes is done using advanced simulation tools in a virtual process, e.g. FEM-studies. The modification of the free parameters represents the different variants to be analysed. So experienced engineers may derive useful proposals in an acceptable time if good initial proposals are available. As soon as the number of free parameters growths or the total process takes long times and uses different succeeding forming steps it might be quite difficult to find promising initial ideas. In metal forming another problem has to be considered. The optimization using a series of local improvements, often called a gradient approach may find a local optimum, but this could be far away from a satisfactory solution. Therefore non-deterministic approaches, e.g. Bionic Optimization have to be used. These approaches like Evolutionary Optimization or Particle Swarm Optimization are capable to cover a large range of high dimensional optimization spaces and discover many local optima. So the chance to include the global optimum increases when using such non-deterministic methods. Unfortunately these bionic methods require large numbers of studies of different variants of the process to be optimized. The number of studies tends to increase exponentially with the number of free parameters of the forming process. As the time for one single study might be not too small as well, the total time demand will be inacceptable, taking weeks to months even if high performance computing will be used. Therefore the optimization process needs to be accelerated. Among the many ideas to reduce the time and computer power requirement Meta- and Hybrid Optimization seem to produce the most efficient results. Hybrid Optimization often consists of global searches of promising regions within the parameter space. As soon as the studies indicate that there could be a local optimum, a deterministic study tries to identify this local region. If it shows better performance than other optima found until now, it is preserved for a more detailed analysis. If it performs worse than other optima the region is excluded from further search. Meta-Optimization is often understood as the derivation of Response Surfaces of the functions of free parameters. Once there are enough studies performed, the optimization is done using the Response Surfaces as representatives e.g. for the goal and the restrictions of the optimization problem. Having found regions where interesting solutions are to be expected, the studies available up to now are used to define the Response Surfaces. In many cases low degree polynomials are used, defining their coefficients by least square methods. Both proposals Hybrid Optimization and Meta-Optimization, sometimes used in combination often help to reduce the total optimization processes by large numbers of variants to be studied. In consequence they are highly recommended when dealing with time consuming optimization studies.
Verification of an active time constant tuning technique for continuous-time delta-sigma modulators
(2022)
In this work we present a technique to compensate the effects of R-C / g m -C time-constant (TC) errors due to process variation in continuous-time delta-sigma modulators. Local TC error compensation factors are shifted around in the modulator loop to positions where they can be implemented efficiently with finely tunable circuit structures, such as current-steering digital-to-analog converters (DAC). We apply our technique to a third-order, single-bit, low-pass continuous-time delta-sigma modulator in cascaded integrator feedback structure, implemented in a 0.35-μm CMOS process. A tuning scheme for the reference currents of the feedback DACs is derived as a function of the individual TC errors and verified by circuit simulations. We confirm the tuning technique experimentally on the fabricated circuit over a TC parameter variation range of ±20%. Stable modulator operation is achieved for all parameter sets. The measured performances satisfy the expectations from our theoretical calculations and circuit-level simulations.
Despite the unstoppable global drive towards electric mobility, the electrification of sub-Saharan Africa’s ubiquitous informal multi-passenger minibus taxis raises substantial concerns. This is due to a constrained electricity system, both in terms of generation capacity and distribution networks. Without careful planning and mitigation, the additional load of charging hundreds of thousands of electric minibus taxis during peak demand times could prove catastrophic. This paper assesses the impact of charging 202 of these taxis in Johannesburg, South Africa. The potential of using external stationary battery storage and solar PV generation is assessed to reduce both peak grid demand and total energy drawn from the grid. With the addition of stationary battery storage of an equivalent of 60 kWh/taxi and a solar plant of an equivalent of 9.45 kWpk/taxi, the grid load impact is reduced by 66%, from 12 kW/taxi to 4 kW/taxi, and the daily grid energy by 58% from 87 kWh/taxi to 47 kWh/taxi. The country’s dependence on coal to generate electricity, including the solar PV supply, also reduces greenhouse gas emissions by 58%.
The coupling of the heat and power sector is required as supply and demand in the German electricity mix drift further and further apart with a high percentage of renewable energy. Heat pumps in combination with thermal energy storage systems can be a useful way to couple the heat and power sectors. This paper presents a hardware-in the-loop test bench for experimental investigation of optimized control strategies for heat pumps. 24-hour experiments are carried out to test whether the heat pump is able to serve optimized schedules generated by a MATLAB algorithm. The results show that the heat pump is capable of following the generated schedules, and the maximum deviation of the operational time between schedule and experiment is only 3%. Additionally, the system can serve the demand for space heating and DHW at any time.
In kleinen und mittleren Unternehmen (KMU) werden Energieeffizienz-Potentiale in geringerem Maße ausgeschöpft als in Großunternehmen. Zugleich bilden KMU den überwältigenden Anteil deutscher Unternehmen. Die Steigerung der Energieeffizienz verspricht einen substanziellen Beitrag zur Umweltentlastung. Energiemanagement wird gemeinhin als wesentlicher Treiber von Energieeffizienz Maßnahmen in Deutschland betrachtet. Im Kontext von Unternehmen wird Energiemanagement üblicherweise synonym mit dem Energiemanagement-standard ISO 50001 betrachtet. Problematisch zeigt sich diese Perspektive mit Blick auf KMU, für die eine aufwändige Implementierung eines solchen System in den überwiegenden Fällen nicht infrage kommt. Vor diesem Hintergrund darf sich eine Förderung von Energiemanagement in KMU jedoch nicht entmutigen lassen. Im Rahmen des Projekts wurde ein bedarfsgerechtes und an den Bedürfnissen von KMU orientiertes Konzept von Energiemanagement für KMU entwickelt. Die Ausarbeitung erfolgte in einem sogenannten Reallabor, das gleichsam als Partner-Netzwerk die Ergebnisse des Projekts kooperativ produziert hat. Das Reallabor setzte sich zusammen aus den koordinierenden Partnern aus der Wissenschaft (REZ Hochschule Reutlingen, Institut für Energieeffizienz in der Produktion EEP), sechs KMU aus der Region Reutlingen und einem Sounding-Board bestehend aus vier weiteren Partnern.
Im Rahmen des Reallabors wurden jene Bausteine definiert, die Energiemanagement für KMU ausmachen. Sensibilität und Basiswissen ist für KMU unumgänglich in den Bereichen: 1. Motivation für Energieeffizienz & Klimaneutralität, 2. Organisation-Entscheiden-Verhalten, 3. Energie-Daten Management und 4. Energieeffizienz-Maßnahmen (Querschnitt-Technologien). Den vier festgelegten Bausteinen wurden unterschiedliche Inhalte Schwerpunkte zugeordnet. Die Bausteine und Schwerpunkte wurden jeweils begründet und mit konkreten Lehr-, Lern- und Sensibilisierungszielen benannt. Parallel zur Festlegung der Bausteine und Schwerpunkte von Energiemanagement wurden Lehr-, Lern- und Sensibilisierungs-Materialien ausgearbeitet, bestehend aus Leitfäden und Checklisten. Die Ausarbeitung wurde jeweils mit Themen-Workshops parallel begleitet. Die entwickelten Lehr-, Lern- und Sensibilisierungs-Materialien wurden in und mit den Partnerunternehmen getestet. Alle Materialien stehen mit Abschluss des Projekts für die Verbreitung zur freien Verfügung.
Der zukünftige Beitrag zur Umweltentlastung hängt von der breiten Umsetzung außerhalb des Projektkontexts ab. Die Sensibilisierung und Qualifizierung für Energiemanagement schafft eine nachhaltige Energiesparkultur in KMU. Eine breite Anwendung des entwickelten Konzepts im Rahmen von moderierten Unternehmens-Netzwerken fördert die nachhaltige Befähigung von KMU Energieeffizienz zu planen und umzusetzen.
Universelle OTA-Testbench
(2014)
Es wird eine universell einsetzbare Testbench zur Simulation von integrierten Schaltungen innerhalb der OTA-Schaltungsklasse (Operational Transconductance Amplifier; Transkonduktanzverstärker) vorgestellt. Transkonduktanzverstärker sind in der analogen Schaltungstechnik weit verbreitet und daher von großer Bedeutung. Sie treten sowohl als eigenständige Schaltungen innerhalb eines Chips, sowie als Bestandteil anderer Schaltungen (z.B. als erste und zweite Stufe von Operationsverstärkern) auf. Es kann davon ausgegangen werden, dass heute kaum ein analoger oder Mixed-Signal-Chip gefertigt wird, in dem keine Transkonduktanzverstärker verbaut sind. Die Entscheidungsfindung des Entwicklers bei der Auslegung eines OTAs beruht maßgeblich auf einer anwendungsspezifischen Simulation. Die Erstellung einer eigenen Testbench für jede Anwendung bedeutet allerdings einen hohen Zeitaufwand und erschwert den Vergleich der Simulationsergebnisse unterschiedlicher Schaltungsvarianten. Durch eine universelle Testbench kann zum einen der Zeitaufwand verringert werden, zum anderen können nun Simulationsergebnisse direkt miteinander verglichen werden. Hierdurch wird die Entscheidungsfindung des Entwicklers objektiviert und beschleunigt. Neben dem Vergleich unterschiedlicher Schaltungen innerhalb einer Technologie ist auch der Vergleich einer Schaltung in unterschiedlichen Technologien denkbar. Die Idee einer universell anwendbaren Testbench lässt sich auch auf andere analoge Schaltungsklassen anwenden und damit als Prinzip verallgemeinern.
The experimental characterization of the thermal impedance Zth of large power MOSFETs is commonly done by measuring the junction temperature Tj in the cooling phase after the device has been heated, preferably to a high junction temperature for increased accuracy. However, turning off a large heating current (as required by modern MOSFETs with low on-state resistances) takes some time because of parasitic inductances in the measurement system. Thus, most setups do not allow the characterization of the junction temperature in the time range below several tens of μs.
In this paper, an optimized measurement setup is presented which allows accurate Tj characterization already 3 μs after turn-off of heating. With this, it becomes possible to experimentally investigate the influence of thermal capacitances close to the active region of the device. Measurement results will be presented for advanced power MOSFETs with very large heating currents up to 220 A. Three bonding variants are investigated and the observed differences will be explained.
This paper aims at presenting a solution that enables end customers of the energy system to participate in new local micro-energy-markets by providing them with a distributed, decentralized, transparent and secure Peer to Peer (P2P) payment system, which functions automatically applying new concepts of Machine to Machine (M2M) communication technologies. This work was performed within the German project VK_2G, funded by the DBU. The key results were: Providing means to perform microtransactions in a P2P fashion between end consumers and prosumers in local communities at low cost in a transparent and secure manner; Developing a platform with pre-defined smart contracts able to be tailored to different end customers ‘needs in an easy way and; Integrating both the market platform as well as the local control of generation and loads. This solution has been developed, integrated and tested in a laboratory prototype. This paper discusses this solution and presents the results of the first test.
The aim of this work is the development of artificial intelligence (AI) application to support the recruiting process that elevates the domain of human resource management by advancing its capabilities and effectiveness. This affects recruiting processes and includes solutions for active sourcing, i.e. active recruitment, pre-sorting, evaluating structured video interviews and discovering internal training potential. This work highlights four novel approaches to ethical machine learning. The first is precise machine learning for ethically relevant properties in image recognition, which focuses on accurately detecting and analysing these properties. The second is the detection of bias in training data, allowing for the identification and removal of distortions that could skew results. The third is minimising bias, which involves actively working to reduce bias in machine learning models. Finally, an unsupervised architecture is introduced that can learn fair results even without ground truth data. Together, these approaches represent important steps forward in creating ethical and unbiased machine learning systems.
In this work, a comparison between different brushless harmonic-excited wound-rotor synchronous machines is performed. The general idea of all topologies is the elimination of the slip rings and auxiliary windings by using the already existing stator and rotor winding for field excitation. This is achieved by injecting a harmonic airgap field with the help of power electronics. This harmonic field does not interact with the fundamental field, it just transfers the excitation power across the airgap. Alternative methods with varying number of phases, different pole-pair combinations, and winding layouts are covered and compared with a detailed Finite-Element-parameterized model. Parasitic effects due to saturation and coupling between the harmonic and main windings are considered.
The increase in distributed energy generation, such as photovoltaic systems (PV) or combined heat and power plants (CHP), poses new challenges to almost every distribution network operator (DNO). In the low-voltage (LV) grids, where installed PV capacity approaches the magnitude of household load, reverse power flow occurs at the secondary substa-tions. High PV penetration leads to voltage rise, flicker and loading problems. These problems have been addressed by the application of various techniques amongst which is the deployment of step voltage regulators (SVR). SVR can solve the voltage problem, but do not prevent or reduce reverse power flows. Therefore, the application of SVR in low voltage grids can result in significant power losses upstream. In this paper we present part of a research project investi-gating the application of remote-controlled cable cabinets (CC) with metering units in a low-voltage network as a possible alternative for SVR. A new generation of custom-made remote-control cable cabinets has been deployed and dynamic network reconfigurations (NR) have been realized with the following objectives: (i) reduction of reverse power flow through the secondary substation to the upstream network and therefore a reduction of upstream losses, (ii) reduction of the voltage rise caused by distributed energy resources and (iii) load balancing in the low-voltage grid. Secondary objec-tives are to improve the DNO's insight into the state of the network and to provide further information on future smart grid integration.
In the course of a more intensive energy generation from regenerative sources, an increased number of energy storages is required. In addition to the widespread means of storing electric energy, storing energy thermally can contribute significantly. However, limited research exists on the behaviour of thermal energy storages (TES) in practical operation. While the physical processes are well known, it is nevertheless often not possible to adequately evaluate its performance with respect to the quality of thermal stratification inside the tank, which is crucial for the thermodynamic effectiveness of the TES. The behaviour of a TES is experimentally investigated in cyclic charging and discharging operation in interaction with a cogeneration (CHP) unit at a test rig in the lab. From the measurements the quality of thermal stratification is evaluated under varying conditions using different metrics such as normalised stratification factor, modified MIX number, exergy number and exergy efficiency, which extends the state of art for CHP applications. The results show that the positioning of the temperature sensors for turning the CHP unit on and off has a significant influence on both the effective capacity of a TES and the quality of thermal stratification inside the tank. It is also revealed that the positioning of at least one of these sensors outside the storage tank, i.e. in the return line to the CHP unit, prevents deterioration of thermal stratification, thereby enhancing thermodynamic effectiveness. Furthermore, the effects of thermal load and thermal load profile on effective capacity and thermal stratification are discussed, even though these are much smaller compared to the effect of positioning the temperature sensors.
In der Mikroelektronik werden Chips häufig in Mold-Gehäusen verpackt. Die elektrischen Verbindungen vom Chip zu den Anschlussbeinchen des Gehäuses werden mit Bonddrähten realisiert. Für die Berechnung der Gleichgewichtstemperatur in einem Bonddraht bei konstantem Strom sowie von Temperaturverläufen bei transienten Strömen ist die herkömmliche FEM-Methode langsam und unhandlich. Daher wurde der Bondrechner entwickelt, der ein zylindersymmetrisches Ersatz-Modell für das Package in geeigneten mathematischen Gleichungen abbildet.
Im Gegensatz zum Bondrechner der ersten Generation [1], der auf den Gleichungen von [2] basiert, bietet ein neuer mathematischer Ansatz die Möglichkeit, eine endliche effektive Package-Größe, sowie einen endlichen Wärmeübergang zwischen Bonddraht und Mold-Masse zu berücksichtigen. Ebenso wurde die Berechnung der Interaktion von mehreren benachbarten Drähten verfeinert. Die Berechnung von beliebigen transienten Pulsformen mittlerer Länge wurde ebenfalls verbessert. Eine quadratische Komponente in der Temperaturabhängigkeit des spezifischen Widerstandes des Drahtmaterials kann jetzt ebenfalls berücksichtigt werden.
Die Ergebnisse wurden erfolgreich mit FEM-Berechnungen verglichen und die Geschwindigkeit der Berechnung ist um Größenordnungen schneller als mit kommerziellen FEM-Programmen.
This paper investigates the electrothermal stability and the predominant defect mechanism of a Schottky gate AlGaN/GaN HEMT. Calibrated 3-D electrothermal simulations are performed using a simple semiempirical dc model, which is verified against high-temperature measurements up to 440°C. To determine the thermal limits of the safe operating area, measurements up to destruction are conducted at different operating points. The predominant failure mechanism is identified to be hot-spot formation and subsequent thermal runaway, induced by large drain–gate leakage currents that occur at high temperatures. The simulation results and the high temperature measurements confirm the observed failure patterns.
Electromigration (EM) is becoming a progressively severe reliability challenge due to increased interconnect current densities. A shift from traditional (post-layout) EM verification to robust (pro-active) EM aware design - where the circuit layout is designed with individual EM-robust solutions - is urgently needed. This tutorial will give an overview of EM and its effects on the reliability of present and future integrated circuits (ICs). We introduce the physical EM process and present its specific characteristics that can be affected during physical design. Examples of EM countermeasures which are applied in today’s commercial design flows are presented. We show how to improve the EM-robustness of metallization patterns and we also consider mission proiles to obtain application-oriented current density limits. The increasing interaction of EM with thermal migration is investigated as well. We conclude with a discussion of application examples to shift from the current post layout EM verification towards an EM aware physical design process. Its methodologies, such as EM-aware routing, increase the EM-robustness of the layout with the overall goal of reducing the negative impact of EM on the circuit’s reliability.
Purpose
Injury or inflammation of the middle ear often results in the persistent tympanic membrane (TM) perforations, leading to conductive hearing loss (HL). However, in some cases the magnitude of HL exceeds that attributable by the TM perforation alone. The aim of the study is to better understand the effects of location and size of TM perforations on the sound transmission properties of the middle ear.
Methods
The middle ear transfer functions (METF) of six human temporal bones (TB) were compared before and after perforating the TM at different locations (anterior or posterior lower quadrant) and to different degrees (1 mm, ¼ of the TM, ½ of the TM, and full ablation). The sound-induced velocity of the stapes footplate was measured using single-point laser-Doppler-vibrometry (LDV). The METF were correlated with a Finite Element (FE) model of the middle ear, in which similar alterations were simulated.
Results
The measured and calculated METF showed frequency and perforation size dependent losses at all perforation locations. Starting at low frequencies, the loss expanded to higher frequencies with increased perforation size. In direct comparison, posterior TM perforations affected the transmission properties to a larger degree than anterior perforations. The asymmetry of the TM causes the malleus-incus complex to rotate and results in larger deflections in the posterior TM quadrants than in the anterior TM quadrants. Simulations in the FE model with a sealed cavity show that small perforations lead to a decrease in TM rigidity and thus to an increase in oscillation amplitude of the TM mainly above 1 kHz.
Conclusion
Size and location of TM perforations have a characteristic influence on the METF. The correlation of the experimental LDV measurements with an FE model contributes to a better understanding of the pathologic mechanisms of middle-ear diseases. If small perforations with significant HL are observed in daily clinical practice, additional middle ear pathologies should be considered. Further investigations on the loss of TM pretension due to perforations may be informative.
Electronic design automation approaches can roughly be divided into optimizers and procedures. While the former have enabled highly automated synthesis flows for digital integrated circuits, the latter play a vital (but mostly underestimated role) in the analog domain. This paper describes both automation strategies in comparison, identifying two fundamentally different automation paradigms that reflect the two basic design practices known as “top-down” and “bottom-up”. Then, with a focus on the latter, the history of procedural approaches is traced from their
early beginnings until today’s evolvements and future prospects to underline their practical importance and to accentuate their scientific value, both in itself and in the overall context of EDA.
Most Question-answering (QA) systems rely on training data to reach their optimal performance. However, acquiring training data for supervised systems is both time-consuming and resource-intensive. To address this, in this paper, we propose TFCSG, an unsupervised similar question retrieval approach that leverages pre-trained language models and multi-task learning. Firstly, topic keywords in question sentences are extracted sequentially based on a latent topic-filtering algorithm to construct unsupervised training corpus data. Then, the multi-task learning method is used to build the question retrieval model. There are three tasks designed. The first is a short sentence contrastive learning task. The second is the question sentence and its corresponding topic sequence similarity judgment task. The third is using question sentences to generate their corresponding topic sequence task. The three tasks are used to train the language model in parallel. Finally, similar questions are obtained by calculating the cosine similarity between sentence vectors. The comparison experiment on public question datasets that TFCSG outperforms the comparative unsupervised baseline method. And there is no need for manual marking, which greatly saves human resources.
3D assisted 2D face recognition involves the process of reconstructing 3D faces from 2D images and solving the problem of face recognition in 3D. To facilitate the use of deep neural networks, a 3D face, normally represented as a 3D mesh of vertices and its corresponding surface texture, is remapped to image-like square isomaps by a conformal mapping. Based on previous work, we assume that face recognition benefits more from texture. In this work, we focus on the surface texture and its discriminatory information content for recognition purposes. Our approach is to prepare a 3D mesh, the corresponding surface texture and the original 2D image as triple input for the recognition network, to show that 3D data is useful for face recognition. Texture enhancement methods to control the texture fusion process are introduced and we adapt data augmentation methods. Our results show that texture-map-based face recognition can not only compete with state-of-the-art systems under the same precon ditions but also outperforms standard 2D methods from recent years.
This paper covers test and verification of a forecast-based Monte Carlo algorithm for an optimized, demand-oriented operation of combined heat and power (CHP) units using the hardware-in-the-loop approach. For this purpose, the optimization algorithm was implemented at a test bench at Reutlingen University for controlling a CHP unit in combination with a thermal energy storage, both in real hardware. In detail, the hardware-in-the-loop tests are intended to reveal the effects of demand forecasting accuracy, the impact of thermal energy storage capacity and the influence of load profiles on demand-oriented operation of CHP units. In addition, the paper focuses on the evaluation of the content of energy in the thermal energy storage under practical conditions. It is shown that a 5-layer model allows to determine the energy stored quite accurately, which is verified by experimental results. The hardware-in-the-loop tests disclose that demand forecasting accuracies, especially electricity demand forecasting, as well as load profiles strongly impact the potential for CHP electricity utilization on-site in demand-oriented mode. Moreover, it is shown that a larger effective capacity of the thermal energy storage positively affects demand-oriented operation. In the hardware-in-the-loop tests, the fraction of electricity generated by the CHP unit utilized on-site could thus be increased by a maximum of 27% compared to heat-led operation, which is still the most common modus operandi of small-scale CHP plants. Hence, the hardware-in-the-loop tests were adequate to prove the significant impact of the proposed algorithm for optimization of demand-oriented operation of CHP units.
Virtual prototyping of integrated mixed-signal smart-sensor systems requires high-performance co-simulation of analog frontend circuitry with complex digital controller hardware and embedded real-time software. We use SystemC/TLM 2.0 in combination with a cycle-count accurate temporal decoupling approach to simulate digital components and firmware code execution at high speed while preserving clock cycle accuracy and, thus, real-time behavior at time quantum boundaries. Optimal time quanta ensuring real-time capability can be calculated and set automatically during simulation if the simulation engine has access to exact timing information about upcoming communication events. These methods fail in case of non-deterministic, asynchronous events resulting in a possibly invalid simulation result. In this paper, we propose an extension of this method to the case of asynchronous events generated by blackbox sources from which a-priori event timing information is not available, such as coupled analog simulators or hardware in the loop. Additional event processing latency and/or rollback effort caused by temporal decoupling is minimized by calculating optimal time quanta dynamically in a SystemC model using a linear prediction scheme. For an example smart-sensor system model, we show that quasi- periodic events that trigger activities in temporally decoupled processes are handled accurately after the predictor has settled.
Virtual prototyping of integrated mixed-signal smart sensor systems requires high-performance co-simulation of analog frontend circuitry with complex digital controller hardware and embedded real-time software. We use SystemC/TLM 2.0 in conjunction with a cycle-count accurate temporal decoupling approach (TD) to simulate digital components and firmware code execution at high speed while preserving clock-cycle accuracy and, thus, real-time behavior at time quantum boundaries. Optimal time quanta ensuring real-time capability can be calculated and set automatically during simulation if the simulation engine has access to exact timing information about upcoming inter-process communication events. These methods fail in the case of non-deterministic, asynchronous events, resulting in potentially invalid simulation results. In this paper, we propose an extension to the case of asynchronous events generated by blackbox sources from which a priori event timing information is not available, such as coupled analog simulators or hardware in the loop. Additional event processing latency or rollback effort caused by temporal decoupling is minimized by calculating optimal time quanta dynamically in a SystemC model using a linear prediction scheme. We analyze the theoretical performance of the presented predictive temporal decoupling approach (PTD) by deriving a cost model that expresses the expected simulation effort in terms of key parameters such as time quantum size and CPU time per simulation cycle. For an exemplary smart-sensor system model, we show that quasi-periodic events that trigger activities in TD processes are handled accurately after the predictor has settled.
When a bonding wire becomes too hot, it fuses and fails. The ohmic heat that is generated in the wire can be partially dissipated to a mold package. For this cooling effect the thermal contact between wire and package is an important parameter. Because this parameter can degrade over lifetime, the fusing of a bonding wire can also occur as a long-term effect. Another important factor is the thermal power generated in the vicinity of the bond pads. Nowadays, the reliability of bond wires relies on robust dimensioning based on estimations. Smaller package sizes increase the need for better predictive methods.
The Bond Calculator, a new thermo-electrical simulation tool, is able to predict the temperature profiles along bond wires of arbitrary dimensions in dependence on the applied arbitrary transient current profile, the mold surrounding the wire, and the thermal contact between wire and mold.
In this paper we closely investigated the spatial temperature profiles along different bond wires in air in order to make a first step towards the experimental verification of the simulation model. We are using infrared microscopy in order to measure the thermal radiation generated along the bond wire. This is easier to perform quantitatively in air than in the mold package, because of the non-negligible absorbance of the mold material in the infrared wavelength region.
We discuss the fabrication technologies for IC chips in this chapter. We will focus on the main process steps and especially on those aspects that are of particular importance for understanding how they affect, and in some cases drive, the layout of ICs. All our analyses in this chapter will be for silicon as the base material; the principles and understanding gained can be applied to other substrates as well. Following a brief introduction to the fundamentals of IC fabrication (Sect. 2.1) and the base material used in it, namely silicon (Sect. 2.2), we discuss the photolithography process deployed for all structuring work in Sect. 2.3. We will then present in Sect. 2.4 some theoretical opening remarks on typical phenomena encountered in IC fabrication. Knowledge of these phenomena is very useful for understanding the process steps we cover in Sects. 2.5–2.8. We examine a simple exemplar process in Sect. 2.9 and observe how a field-effect transistor (FET) – the most important device in modern integrated circuits—is created. To drive the key points home, we provide a review of each topic at the end of every section from the point of view of layout design by discussing relevant physical design aspects.
In Germany, mobility is currently in a state of flux. Since June 2019, electric kick scooters (e-scooters) have been permitted on the roads, and this market is booming. This study employs a user survey to generate new data, supplemented by expert interviews to determine whether such e-scooters are a climate-friendly means of transport. The environmental impacts are quantified using a life cycle assessment. This results in a very accurate picture of e-scooters in Germany. The global warming potential of an e-scooter calculated in this study is 165 g CO2-eq./km, mostly due to material and production (that together account for 73% of the impact). By switching to e-scooters where the battery is swapped, the global warming potential can be reduced by 12%. The lowest value of 46 g CO2-eq./km is reached if all possibilities are exploited and the life span of e-scooters is increased to 15 months. Comparing these emissions with those of the replaced modal split, e-scooters are at best 8% above the modal split value of 39 g CO2-eq./km.
In recent years, significant progress was made on switched-capacitor DCDC converters as they enable fully integrated on chip power management. New converter topologies overcame the fixed input-to-output voltage limitation and achieved high efficiency at high power densities. SC converters are attractive to not only mobile handheld devices with small input and output voltages, but also for power conversion in IoTs, industrial and automotive applications, etc. Such applications need to be capable of handling high input voltages of more than 10V. This talk highlights the challenges of the required supporting circuits and high voltage techniques, which arise for high Vin SC converters. It includes level shifters, charge pumps and back-to-back switches. High Vin conversion is demonstrated in a 4:1 SC DCDC converter with an input voltage as high as 17V with a peak efficiency of 45 %, and a buckboost SC converter with an input voltage range starting from 2 up to 13V, which utilizes a total of 17 ratios and achieves a peak efficiency of 81.5 %. Furthermore a highly integrated micro power supply approach is introduced, which is connected directly to the 120/230 Vrms mains, with an output power of 3mW, resulting in a power density >390μW/mm², which exceeds prior art by a factor of 11.
Optimization-based analog layout automation does not yet find evident acceptance in the industry due to the complexity of the design problem. This paper presents a Self-organized Wiring and Arrangement of Responsive Modules (SWARM), able to consider crucial design constraints both implicitly and explicitly. The flexibility of algorithmic methods and the expert knowledge captured in PCells combine into a flow of supervised module interaction. This novel approach targets the creation of constraint-compliant layout blocks which fit into a specified zone. Provoking a synergetic self-organization, even optimal layout solutions can emerge from the interaction. Various examples depict the power of that new concept and the potential for future developments.
Despite 30 years of Electronic Design Automation, analog IC layouts are still handcrafted in a laborious fashion today due to the complex challenge of considering all relevant design constraints. This paper presents Self-organized Wiring and Arrangement of Responsive Modules (SWARM), a novel approach addressing the problem with a multi-agent system: autonomous layout modules interact with each other to evoke the emergence of overall compact arrangements that fit within a given layout zone. SWARM´s unique advantage over conventional optimization-based and procedural approaches is its ability to consider crucial design constraints both explicitly and implicitly. Several given examples show that by inducing a synergistic flow of self-organization, remarkable layout results can emerge from SWARM’s decentralized decision-making model.
This paper evaluates experimentally the susceptibility of IT-networks under influences and the threats of HPEM (High Power Electromagnetic) and IEMI (Intentional Electromagnetic Interferences). As HPEM source a PBG 5 (Pulse Burst Generator) adapted to a TEM (Transversal Electromagnetic) Horn type antenna and a 90 cm IRA (Impulse Radiating Antenna) type antenna is used. Different network cable types and categories with different lengths are used. The immunity of the IT network is examined and the breakdown failure rate of the system is defined for a PRF (Pulse Repetition Frequency) of 500 s-1 in duration of 10 seconds. Series of measurements were carried out and disturbances of keyboards, mouse, switches, distortions on monitors and failures of the IT network and, even crash of PCs were observed. It is shown amongst other that by increasing the pulse repetition rate or frequency, generic test IT-networks are more susceptible to interference. Obtained results provide another view of the susceptibility analysis of modern generic IT-networks against UWB-Threats.
Durch schnell schaltende Leistungsendstufen werden durch kapazitive Umladeströme Störungen ins Substrat und in empfindliche Schaltungselemente eingekoppelt, die dort zur Störung der Funktion führen können. In dieser Arbeit werden Substratstrukturen zur gezielten Ableitung dieser Störungen vorgestellt und ihre Wirksamkeit mit Hilfe von Device Simulation evaluiert. Ohne Ableitstrukturen kann eine Potentialanhebung des Substrats bis zu 20 V entstehen. Die Untersuchungen belegen, dass die Potentialanhebung durch p-Typ Guard-Ringe um 75 %, durch leitende Trenches um 88 % sowie durch Rückseitenmetallisierung um nahezu 100 % reduziert werden kann.
Substrate coupling is a critical failure mechanism especially in fast-switching integrated power stages controlling high-side NMOS power FETs. The parasitic coupling across the substrate in integrated power stages at rise times of up to 500 ps and input voltages of up to 40V is investigated in this paper. The coupling has been studied for the power stage of an integrated buck converter. In particular, dedicated diverting and isolation structures against substrate coupling are analyzed by simulations and evaluated with measurements from test chips in 180nm high-voltage BiCMOS. The results are compared regarding effectiveness, area as well as implementation effort and cost. Back-side metalization shows superior characteristics with nearly 100% noise suppression. Readily available p-guard ring structures bring 75% disturbance reduction. The results are applicable to advanced and future power management solutions with fully integrated switched-mode power supplies at switching frequencies >10 MHz.
The deterioration of the shielding performance of electromagnetic interference finger stock gaskets in a corrosive environment is investigated. The visualization of the real contact area shows a drastic reduction of the engaged active contact region between fingers and their mating surfaces in presence of corrosives residues. In fact, additional openings occur besides the “Tlike” holes due to the porous nature of gaskets. This leads to a strong degradation of the shielding effectiveness. Modified Bethe’s theory is used to estimate the equivalent circuit parameters while the shielding effectiveness in terms of ratio between two transfer functions is obtained upon applying the filter theory. Quantitative measurements carried out for different gasket types show a good agreement with calculated results, demonstrating thus the validity of the approach.
Die zunehmende erneuerbare Stromerzeugung erfordert Anstrengungen, um den Angebotsschwankungen und der Verteilungsproblematik entgegen zu wirken. Eine dezentrale und am Bedarf orientierte Stromerzeugung mittels Kraft-Wärme-Kopplung (KWK) kann einen wesentlichen Beitrag leisten, um diese Schwankungen auszugleichen und die Netze zu entlasten. Zu diesem Zweck ist aber ein Steuerungssystem für die KWK-Anlagen erforderlich, das sowohl für die Deckung des Wärmebedarfs im Objekt sorgt, als auch gewährleistet, dass die elektrische Energie genau zu den Zeiten erzeugt wird, zu denen sie im Objekt benötigt wird. Die Entkopplung von Stromerzeugung und Deckung des Wärmebedarfs kann dabei über den standardmäßig vorhandenen Wärmespeicher erfolgen. Dieser stellt damit das zentrale Element der Gesamtanlage dar, für die das Steuerungssystem zur Eigenstromoptimierung im Rahmen des Forschungsvorhabens entwickelt und erprobt werden soll.
Im Rahmen des vorliegenden Zwischenberichtes werden die Ergebnisse des 2. des auf insgesamt drei Jahre angelegten Forschungsprojektes vorgestellt. Im Einzelnen sind die Themen Prognose, Bestimmung des Energieinhaltes im Wärmespeicher, stromoptimiertes Steuerungssystem, Aufbau der Feldtestanlagen, Simulation und sozialwissenschaftliche Begleitforschung beschrieben.
Bei den umfangreichen Arbeiten zur Wärme- und Strombedarfsprognose hat sich gezeigt, dass die naive Prognose, die auf der Übernahme der Daten der Vortage beruht, aufgrund des starken Einflusses des individuellen Nutzerverhaltens eine nur schwer zu verbessernde Vorhersagegüte aufweist. Zur Bestimmung des Energieinhaltes im Wärmespeicher wird eine Sigmoidfunktion zur Beschreibung des Temperaturverlaufs über der Speicherhöhe verwendet. Schwierig ist dabei die Anpassung der vier Funktionsparameter mit nur drei Temperaturmesswerten, was jedoch durch geeignete Randbedingungen erreicht werden kann. Das stromoptimierte Steuerungssystem verwendet die Wärmebedarfskurven bei minimalem und maximalem Energieinhalt des Wärmespeichers als Begrenzungen des Optimierungsbereiches, um so die Deckung des Wärmebedarfs zu jeder Zeit zu gewährleisten. Die zwei im Projekt zur Verfügung stehenden Feldtestanlagen wurden mit zusätzlicher Mess- und Steuerungstechnik nachgerüstet, um das entwickelte Steuerungssystem implementieren und testen zu können. Das Simulationsmodell ist im Hinblick auf verschiedene Speicherkonfigurationen erweitert und auf Basis am BHKW-Prüfstand der Hochschule gewonnener Versuchsdaten verifiziert worden, und im Zuge der sozialwissenschaftlichen Begleitforschung werden die Ergebnisse einer im Rahmen des Projektes angefertigten Studie zu den Hemmnissen der KWK vorgestellt.
Die zunehmende erneuerbare Stromerzeugung erfordert Anstrengungen, um den damit verbundenen Angebotsschwankungen und der zusätzlichen Netzbelastung entgegen zu wirken. Eine dezentrale und am Bedarf orientierte Stromerzeugung mittels Kraft-Wärme-Kopplung (KWK) kann hier einen wesentlichen Beitrag leisten, um eine sichere und konstante Stromversorgung zu gewährleisten und die Netze zu entlasten. Zu diesem Zweck ist jedoch ein Steuerungssystem erforderlich, das die KWK-Anlagen in die Lage versetzt, sowohl die Deckung des Wärmebedarfs im Objekt aufrecht zu erhalten, als auch die elektrische Energie genau zu den Zeiten zu erzeugen, in denen sie benötigt wird. Die Entkopplung von Stromerzeugung und Deckung des Wärmebedarfs kann dabei über den standardmäßig vorhandenen Wärmespeicher erfolgen. Dieser stellt damit das zentrale Element der Gesamtanlage dar, für die das Steuerungssystem zur Eigenstromoptimierung im Rahmen des Forschungsvorhabens entwickelt und erprobt wurde.
Der Wärmespeicher einer KWK-Anlage kann genutzt werden, um den Betrieb des BHKWs in die Zeiten des Stromverbrauchs zu verlagern. Die Ad-hoc-Zuschaltfunktion verbessert das Ergebnis gegenüber eines auf Basis von Prognosen erstellten Fahrplans. Zu beachten sind allerdings eine erhöhte Anzahl BHKW-Starts und erhöhte Wärmeverluste am Speicher. Die deutlich besten Ergebnisse werden für BHKW mit Leistungsmodulation erzielt.
In dem vorliegenden Zwischenbericht sind die Arbeiten und Ergebnisse zusammengefasst, die im Rahmen des Projektes GalvanoFlex_BW während der ersten acht Projektmonate der insgesamt 2 1/2 jährigen Laufzeit durchgeführt und erzielt wurden. Ziel des Projektes ist die Untersuchung und Verbesserung der Energieeffizienz in Industrieunternehmen mit dem speziellen Fokus auf der Einführung stromoptimiert betriebener KWK-Anlagen. Entsprechend des Arbeits- und Zeitplans sind die Literaturrecherche, die Festlegung von Prozesstypen, die Datenerfassung, die Strategieentwickung zur stromoptimierten KWK, die Optimierung der Schnittstelle zwischen KWK und Gleichrichtern, der Aufbau der Branchenplattform und die sozial-wissenschaftliche Begleitforschung beschrieben. Der aktuelle Projektstand deckt sich dabei im Wesentlichen mit den Vorgaben aus dem vorgelegten Zeitplan.
Dieser Bericht fasst die wesentlichen Arbeiten und Ergebnisse zusammen, die in dem Verbundvorhaben „GalvanoFlex_BW“ im Kalenderjahr 2018 durchgeführt und erzielt wurden. Dazu lässt sich zunächst sagen, dass die Messwertaufnahme und –auswertung abgeschlossen ist. Es wurden verschiedene Messkampagnen bei der Fa. NovoPlan durchgeführt. Bei C&C Bark konnte man teilweise auf bestehende Daten zurückgreifen, die punktuell durch weitere Messungen ergänzt wurden. Bei der Fa. Hartchrom konnten aufgrund von Personalmangel keine Messungen durchgeführt werden. Die aufgenommenen Daten wurden in eine Effizienzbewertung überführt, aus der im Folgenden allgemeine Aussagen abgeleitet werden sollen. Dazu ist ein Simulationsprogramm aufgesetzt worden, das in der Lage ist, Prozessketten energetisch abzubilden und zu optimieren. Zudem sollen aus den Messdaten verbesserte Profile für den Wärmebedarf in den Unternehmen entwickelt werden, die daraufhin der KWK-Optimierung zur Verfügung gestellt werden. Im Zuge der Entwicklung und Bewertung stromoptimierter KWK- Strategien ist ein bestehendes Simulationsmodell entsprechend weiterentwickelt worden. Konkret wurde das Modell um eine verbesserte Lastprognose für Strom und Wärme für Industriebetriebe ergänzt, und das Optimierungsverfahren wurde um eine zweite Dimension erweitert. Während bislang allein die Optimierung der Eigenstromdeckung mit einer Begrenzung der BHKW-Starts als Nebenbedingung möglich war, ist jetzt die Kappung der elektrischen Lastspitze zusätzlich in der Zielfunktion integriert. Gerade bei Industrieunternehmen lässt sich auf diese Weise eine weitere, zum Teil nicht unerhebliche Energiekosteneinsparung erreichen, was durch die ersten Berechnungen anhand der drei im Reallabor vertretenden Betriebe bestätigt wird. Die Ergebnisse werden unter AP 8 (Umsetzung) diskutiert. Der Dialog mit weiteren Unternehmen und Institutionen außerhalb des Vorhabens konnte über die Branchenplattfom weitergeführt werden. In 2018 wurden zwei Veranstaltungen dieser Art durchgeführt, und im Frühjahr 2019 wird ein weiterer Workshop zu diesem Thema durchgeführt. Die sozialwissenschaftliche Begleitforschung wurde mit der zweiten Phase der Firmenbefragungen ebenfalls planmäßig weitergeführt. Mit Blick auf die Umsetzung eines BHKW-Konzeptes haben sich dabei zwei wichtige Punkte wie folgt gezeigt: Zum einen muss die umsetzende Firma eine gewisse „Energieeffizienz-Reife“ besitzen, die sich u.a. in der Erfahrung bei der Durchführung von Energieeffizienzmaßnahmen zeigt, da die Installation eines BHKWs eine äußerst komplexe Maßnahme darstellt. Zum anderen müssen andere unternehmensspezifische Kontextfaktoren hinzukommen, wie z.B. aus anderen Gründen durchzuführende bauliche Maßnahmen, so dass gewisse zeitliche Entscheidungsfenster entstehen, in denen die Umsetzung von KWK-Maßnahmen sinnvoll sind.
Im Projekt GalvanoFlex_BW sind verschiedene Möglichkeiten zur Verbesserung der Energieeffizienz von energieintensiven Industrieunternehmen aufgezeigt und untersucht worden. Die Einführung der KWK im stromoptimierten Betrieb stellte dabei einen besonders betrachteten Aspekt dar. Neben der technischen Untersuchung ist zudem eine sozialwissenschaftliche Betrachtung vorgenommen worden, um die Einführung und Umsetzung entsprechender Maßnahmen auch unter diesem Aspekt zu betrachten. Ein zusätzlicher wichtiger Schwerpunkt des Projektes war die Übertragung des erarbeiteten Wissens an weitere Unternehmen, Institutionen etc., die nicht direkt am Projekt beteiligt waren.
Durch die Zusammenarbeit von vier Forschungs- und drei Industriepartnern sind die Arbeiten praxisorientiert auf Basis realer Messdaten sowie im Zuge von Befragungen der handelnden Personen bei den Projektpartnern im Sinne eines Reallabors durchgeführt worden.
Die Notwendigkeit zur Einsparung von Energie und damit zur Umsetzung von Effizienzmaßnahmen ist ein wichtiger Schritt, um die von der EU geplante Reduktion von Treibhausgasen zu erreichen. Darüber hinaus ist zu erwarten, dass die Energiekosten auch zukünftig weiter ansteigen. Dadurch werden Maßnahmen zur Steigerung der Energieeffizienz zu einem wichtigen Element, eine wettbewerbsfähige Produktion zu gewährleisten. Im Rahmen des Projektes sind deshalb verschiedene Energieeffizienzmaßnahmen speziell für die Galvanotechnik recherchiert, analysiert und in einen Maßnahmenkatalog überführt worden. Des Weiteren wurde eine Bewertungsmethode entwickelt, die die Unternehmen der Galvanotechnik bei der Identifikation von sinnvollen Energieeffizienzmaßnahmen unterstützen soll.
Bei den Untersuchungen zur Umsetzung von Kraft-Wärme-Kopplungsanlagen konnte am Beispiel von zwei Unternehmen mit stark unterschiedlichen Strom- und Wärmebedarfswerten gezeigt werden, dass der Einsatz entsprechender Anlagen wirtschaftlich lohnenswert ist. Im günstigsten Fall ergeben sich Amortisationszeiten von etwa zwei Jahren. Es hat sich weiterhin gezeigt, dass die Auslegung des Block-heizkraftwerkes stark von den Strom- und Wärmebedarfswerten abhängt und dass der Pufferspeicher keinesfalls zu klein ausgelegt werden sollte. Eine intelligente stromoptimierte Steuerung mit Lastspitzenmanagement kann die Wirtschaftlichkeit jedoch häufig nur noch wenig gegenüber dem wärmegeführten Betrieb verbessern. Ursache dafür ist, dass das derzeitige Förder- und Vergütungssystem für Kraft-Wärme-Kopplungsanlagen nahezu keine Anreize für einen am Strombedarf und damit an der Deckung von Residuallast orientierten Betrieb bietet. Einzig bei Unternehmen mit ausgeprägten Spitzen im Strombezug, kann der gezielte Einsatz eines Blockheizkraftwerkes zu einer signifikanten Senkung des Leistungspreises führen.
Darüber hinaus ist die Einführung einer Kraft-Wärme-Kopplungsanlage generell als komplexe Energieeffizienzmaßnahme anzusehen, die deshalb neben den wirtschaftlichen Aspekten erhöhte Anforderungen an die Unternehmen und das professionelle Umfeld stellt, die im Rahmen der sozialwissenschaftlichen Begleitforschung untersucht worden sind. Dabei konnten Treiber aber auch Hemmnisse zur Umsetzung der Technologie sowohl innerhalb der Unternehmen als auch außerhalb identifiziert werden. Die internen Hemmnisse sind dabei auf unterschiedliche Ursachen zurückzuführen, wie die hohe Komplexität der KWK-Technologie, die schwierige Bewertung des Gesamtnutzens im Unternehmen, die mangelnde personelle Ausstattung und fehlende Unternehmerentscheidungen. Abhilfe schaffen, und damit als Treiber wirken, können hier ein verbessertes Beratungsangebot insbesondere seitens neutraler Stellen sowie der Anlagenbetrieb im Contracting.
Die Übertragung der im Projekt erarbeiteten Ergebnisse ist bereits während der Projektlaufzeit über die Branchenplattform im Zuge verschiedener Workshops, die speziell auf Unternehmen und Institutionen außerhalb des Projektkonsortiums ausgerichtet waren, erfolgt. Zur Verstärkung der Verbreitung des erarbeiteten Wissens ist zum Projektende eine Serie aus vier Fachartikeln in einem namhaften Branchenmagazin erschienen, und es ist eine Internetseite zum Projekt erstellt worden (www.galvanoflex_bw.de). Letztere hat dabei nicht nur die Aufgabe der Wissensverbreitung, sondern sie soll auch über das Projektende hinaus als Kontaktplattform dienen, um die Umsetzung von Effizienzmaßnahmen mit dem im Projekt generierten Wissen zu unterstützen.
Das Thema Energieflexibilität und Anpassung der eigenerzeugten Energie an die Energieerzeugung aus regenerativen Energien gewinnt an Bedeutung. Regulierbare Eigenerzeugungsanlagen können zur Stabilisierung des Netzes einen enormen Beitrag leisten. Der Aufsatz zeigt, welchen Effekt der Einsatz von BHWK auf die Galvanikbranche hat und wie nicht nur die eigenen Energiekosten reduziert, sondern auch die Möglichkeit geschaffen wird, auf Signale der Energiewirtschaft zu reagieren, ohne die Energieversorgung zu unterbrechen.
This publication gives a short introduction and overview of the European project SCOUT and introduces a methodology for a holistic approach to record the state of the art in technical (vehicle and connectivity, human factors regarding physiologic and ergonomic level) and non-technical enablers (societal, economic, legal, regulatory and policy level) of connected and automated driving in Europe. The paper addresses beside the technical topics of environmental perception, E/E architecture, actuators and security, the state of the art of the legal framework in the context of connected and automated driving.
Micro grids often consist of energy generators, storages and consumers with controllers which are not prepared for their integration into communication networks for energy systems. In this paper it will be presented, how standards from the field of energy automation can be applied in such controllers. The data for communication interfaces can be structured according to the IEC 61850- or the VHPREADY standard. It is investigated which requirements must be supported to implement such data models within the controllers. For the transmission of the data we propose the OPC UA protocol, which supports extensive security measures and which is today available for nearly all modern types of controllers and computers.
We present a compact battery charger topology for weight and cost sensitive applications with an average output current of 9A targeted for 36V batteries commonly found in electric bicycles. Instead of using a conventional boost converter with large DC-link capacitors, we accomplish PFC-functionality by shaping the charging current into a sin²-shape. In addition, a novel control scheme without input-current sensing is introduced. A-priori knowledge is used to implement a feed-forward control in combination with a closed-loop output current control to maintain the target current. The use of a full-bridge/half bridge LLC converter enables operation in a wide input-voltage range.
A fully featured prototype has been built with a peak output power of 1050W. An average output power of 400W was measured, resulting in a power density of 1.8 kW/dm³. At 9A charging current, a power factor of 0.96 was measured and the efficiency exceeds 93% on average with passive rectification.
The impact of pulse charging has been evaluated on a 400Wh battery which was charged with the proposed converter as well as CC-CV-charging for reference. Both charging schemes show similar battery surface temperatures.
Bis zum Jahr 2050 soll in Baden Württemberg mit dem Ziel „50-80-90“ der Energiebedarf um 50% reduziert werden, die erneuerbaren Energien sollen zu 80% an der Energieversorgung beteiligt sein und die Emissionen von Treibhausgasen um 90% sinken.Entsprechende Ziele sind für andere Regionen und Länder in ähnlicher Weise festgelegt.
Damit diese Ziele erreicht werden, muss bei der Gebäudewärmeversorgung ein konsequenter Umbau stattfinden. Hier spielt die Sektorenkopplung mit Hilfe von Wärmepumpen (WP) eine entscheidende Rolle. Zur Abschätzung des Potenzials sowie des Aufwandes für einen großflächigen Einsatz von Wärmepumpen ist es unmöglich, eine spezifische und angepasste Dimensionierung der Wärmepumpensysteme für jedes einzelne Gebäude durchzuführen. Stattdessen müssen auf Seiten der Bebauung Referenzgebäude definiert und auf Seiten der Wärmepumpensysteme mittlere Leistungsdaten der am Markt befindlichen Modelle verwendet werden. Während die Festlegung von Referenzgebäuden verschiedentlich in der Literatur zu finden ist, widmet sich der erste Teil der Veröffentlichung der Vorstellung von Korrelationsfunktionen für die thermische und elektrische Leistung sowie die Leistungszahl (COP) von Wärmepumpen, die auf Basis von Herstellerdaten in Abhängigkeit der Quellen- und Vorlauftemperatur ermittelt wurden.
Konkret wurden als Ausgangsbasis für die Korrelationsfunktionen Datenblätter verschiedener Sole- und Luft-Wasser Wärmepumpen (SWP, LWP) zusammengestellt und ausgewertet. Die Grundlage hierfür war die Liste „Wärmepumpen mit Prüfnachweis eines unabhängigen Prüfinstituts“ des Bundesamts für Wirtschaft und Ausfuhrkontrolle (BAFA).
Durch das Verbot der ozonschädigenden Fluor-Chlorkohlenwasserstoffen als Kältemittel und der heute überwiegend eingesetzten Fluor-Kohlenwasserstoffe, welche sich negativ auf den Treibhauseffekt auswirken, gewinnt das umweltfreundlichere CO2 (Kohlendioxid) in der Verwendung als Kältemittel an Bedeutung. Ausgangspunkt dieser Arbeit sind ein Prototyp einer reversiblen CO2 Wärmepumpe und ein Simulationsmodell derselbigen. Ziel dieser Arbeit ist es das Simulationsmodell, anhand von realen Messergebnissen des Prototyps, zu verifizieren. Durch die Berechnung von Vergleichsparametern, das Festlegen von Randbedingungen und geeigneten Messpunkten am Prototyp wird die Simulation optimiert. Abschließend folgt die Bewertung der Ergebnisse im Hinblick auf die Funktionalität der Wärmepumpe und deren Abbild in der Simulation.
Simulation eines dezentralen Regelungssystems zur netzdienlichen Erzeugung von grünem Wasserstoff
(2023)
Wasserstoff wird einen bedeutenden Beitrag zum Wandel von Industrie und Gesellschaft in eine klimaneutrale Zukunft leisten. Der Aufbau und die ökologisch und ökonomisch sinnvolle Nutzung einer Wasserstoffinfrastruktur sind hierbei die zentralen Herausforderungen. Ein notwendiger Baustein ist die effiziente Bereitstellung von grünem Strom und dem daraus produzierten grünen Wasserstoff. Der vorliegende Beitrag stellt ein dezentrales Regel- und Kommunikationssystem vor, mit dem Angebot und Nachfrage von grünem Strom und Wasserstoff in einem System aus dezentralen Akteuren in Einklang gebracht werden. In einer hierzu entwickelten Simulationsumgebung wird die Funktion und der Nutzen dieses dezentralen Ansatzes verdeutlicht.
In this paper, it aims to model wind speed time series at multiple sites. The five-parameter Johnson distribution is deployed to relate the wind speed at each site to a Gaussian time series, and the resultant m-dimensional Gaussian stochastic vector process Z(t) is employed to model the temporal-spatial correlation of wind speeds at m different sites. In general, it is computationally tedious to obtain the autocorrelation functions (ACFs) and cross-correlation functions (CCFs) of Z(t), which are different to those of wind speed times series. In order to circumvent this correlation distortion problem, the rank ACF and rank CCF are introduced to characterize the temporal-spatial correlation of wind speeds, whereby the ACFs and CCFs of Z(t) can be analytically obtained. Then, Fourier transformation is implemented to establish the cross-spectral density matrix of Z(t), and an analytical approach is proposed to generate samples of wind speeds at m different sites. Finally, simulation experiments are performed to check the proposed methods, and the results verify that the five-parameter Johnson distribution can accurately match distribution functions of wind speeds, and the spectral representation method can well reproduce the temporal-spatial correlation of wind speeds.
The current paper discusses the optimal choice of a filter time constant for filtering the steady state flux reference in an energy efficient control strategy for changing load torques. It is shown that by appropriately choosing the filter time constant as a fraction of the rotor time constant the instantaneous power losses after a load torque step can be significantly reduced compared to the standard case. The analysis for the appropriate choice of the filter time constant is based on a numerical study for three different induction motors with different rated powers.
Modern production systems are characterized by the increasingly use of CPS and IoT networks. However, processing the available information for adaptation and reconfiguration often occurs in relatively large time cycles. It thus does not take advantage of the optimization potential available in the short term. In this paper, a concept is presented that, considering the process information of the individual heterogeneous system elements, detects optimization potentials and performs or proposes adaptation or reconfiguration. The concept is evaluated utilizing a case study in a learning factory. The resulting system thus enables better exploitation of the potentials of the CPPS.
This article illustrates a method for sensorless control of a switched reluctance motor. The detection of the time instants for switching between the working phases is determined based on the evaluation of the switching frequency of the hysteresis current controllers for appropriately selected sensing phases. This enables a simple and cost efficient implementation. The method is compared with a pulse injection method in terms of efficiency and resolution.
For collision and obstacle avoidance as well as trajectory planning, robots usually generate and use a simple 2D costmap without any semantic information about the detected obstacles. Thus a robot’s path planning will simply adhere to an arbitrarily large safety margin around obstacles. A more optimal approach is to adjust this safety margin according to the class of an obstacle. For class prediction, an image processing convolutional neural network can be trained. One of the problems in the development and training of any neural network is the creation of a training dataset. The first part of this work describes methods and free open source software, allowing a fast generation of annotated datasets. Our pipeline can be applied to various objects and environment settings and is extremely easy to use to anyone for synthesising training data from 3D source data. We create a fully synthetic industrial environment dataset with 10 k physically-based rendered images and annotations. Our da taset and sources are publicly available at https://github.com/LJMP/synthetic-industrial-dataset. Subsequently, we train a convolutional neural network with our dataset for costmap safety class prediction. We analyse different class combinations and show that learning the safety classes end-to-end directly with a small dataset, instead of using a class lookup table, improves the quantity and precision of the predictions.
Energy efficient electric control of drives is more and more important for electric mobility and manufacturing industries. Online dynamic optimization of induction machines is challenging due to the computational complexity involved and the variable power losses during dynamic operation of induction machines. This paper proposes a simple technique for sub-optimal online loss optimization using rotor flux linkage templates for energy efficient dynamic operation of induction machines. Such a rotor flux linkage template is given by a rotor flux linkage trajectory which is optimal for a specific scenario. This template is calculated in an offline optimization process. For a specific scenario during real time operation the rotor flux linkage is calculated by appropriately scaling the given template.
Bionic optimisation is one of the most popular and efficient applications of bionic engineering. As there are many different approaches and terms being used, we try to come up with a structuring of the strategies and compare the efficiency of the different methods. The methods mostly proposed in literature may be classified into evolutionary, particle swarm and artificial neural net optimisation. Some related classes have to be mentioned as the non-sexual fern optimisation and the response surfaces, which are close to the neuron nets. To come up with a measure of the efficiency that allows to take into account some of the published results the technical optimisation problems were derived from the ones given in literature. They deal with elastic studies of frame structures, as the computing time for each individual is very short. General proposals, which approach to use may not be given. It seems to be a good idea to learn about the applicability of the different methods at different problem classes and then do the optimisation according to these experiences. Furthermore in many cases there is some evidence that switching from one method to another improves the performance. Finally the identification of the exact position of the optimum by gradient methods is often more efficient than long random walks around local maxima.
Perforations of the tympanic membrane (TM) can occur as a result of injury or inflammation of the middle ear. These perforations can lead to conductive hearing loss (HL), where in some cases the magnitude of HL exceeds that attributable to the observed TM perforation alone. We aim with this study to better understand the effects of location and size of TM perforations on the sound transmitting properties of the middle ear.
The middle ear transfer function (METF) of six human temporal bones (TB; freshly frozen specimen of body donors) were compared before and after perforation of the TM at different locations (anterior or posterior lower quadrant) and of different sizes (1mm, ¼ of the TM, ½ of the TM, and full ablation). The
METF were correlated with a Finite Element (FE) model of the middle ear, in which similar alterations were simulated.
The measured and simulated FE model METFs exhibited frequency and perforation size dependent amplitude losses at all locations and severities. In direct comparison, posterior TM perforations affected the transmission properties to a larger degree than perforations of the anterior quadrant. This could possibly be caused by an asymmetry of the TM, where the malleus-incus complex rotates and results in larger deflections in the posterior TM half than in the anterior TM half. The FE model of the TM with a sealed cavity suggest that small perforations result in a decrease of TM rigidity and thus to an increase in oscillation amplitude of the TM, mostly above 1 kHz.
The location and size of TM perforations influence the METF in a reproducible way. Correlating our data with the FE model could help to better understand the pathologic mechanisms of middle-ear diseases. If small TM perforations with uncharacteristically significant HL are observed in daily clinical practice, additional middle ear pathologies should be considered. Further investigations on the loss of TM pretension due to perforations may be informative.
Die sogenannte Systemsimulation, bei der mehrere physikalische Domänen gemeinsam simuliert werden, erlaubt die Analyse komplexer und damit realitätsnaher Systeme und spielt eine zunehmend größere Rolle bei der Auslegung von Komponenten. Enthält das System Teile, die durch Feldgrößen aus unterschiedlichen physikalischen Domänen beschrieben werden müssen, kann man Co-Simulationen einsetzen, die allerdings zeitaufwändig sind. Für die Auslegung des Systems ist es dagegen notwendig, Systemsimulationen schnell durchzuführen zu können. Hierfür können für ausgewählte Bauteile oder Domänen schnellere reduzierte Ersatzmodelle (ROM) eingesetzt werden. In dieser Arbeit stellen wir ein reduziertes Modell für elektromechanische Bauteile mit Berücksichtigung von Wirbelströmen vor. Wirbelstromeffekte hängen nicht nur vom aktuellen Zustand, sondern auch von der Geschichte der elektromagnetischen Domäne ab. Das vorgestellte Ersatzmodell basiert auf Daten, die mit einer Reihe von stationären Feldsimulationen vorab erzeugt werden. Für die Modellierung der geschichtsabhängigen Wirbelstromeffekte wird ein Konvolutionsansatz (Faltungsansatz) verwendet. Vergleiche mit entsprechenden Co-Simulationen in ANSYS Maxwell und Simplorer zeigen am Beispiel eines Hubankers, dass das Ersatzmodell in der Lage ist, die wesentlichen Eigenschaften des Bauteils physikalisch korrekt abzubilden.
Reconstructing 3D face shape from a single 2D photograph as well as from video is an inherently ill-posed problem with many ambiguities. One way to solve some of the ambiguities is using a 3D face model to aid the task. 3D morphable face models (3DMMs) are amongst the state of the art methods for 3D face reconstruction, or so called 3D model fitting. However, current existing methods have severe limitations, and most of them have not been trialled on in-the-wild data. Current analysis-by- synthesis methods form complex non linear optimisation processes, and optimisers often get stuck in local optima. Further, most existing methods are slow, requiring in the order of minutes to process one photograph.
This thesis presents an algorithm to reconstruct 3D face shape from a single image as well as from sets of images or video frames in real-time. We introduce a solution for linear fitting of a PCA shape identity model and expression blendshapes to 2D facial landmarks. To improve the accuracy of the shape, a fast face contour fitting algorithm is introduced. These different components of the algorithm are run in iteration, resulting in a fast, linear shape-to- landmarks fitting algorithm. The algorithm, specifically designed to fit to landmarks obtained from in-the-wild images, by tackling imaging conditions that occur in in-the-wild images like facial expressions and the mismatch of 2D–3D contour correspondences, achieves the shape reconstruction accuracy of much more complex, nonlinear state of the art methods, while being multiple orders of magnitudes faster.
Second, we address the problem of fitting to sets of multiple images of the same person, as well as monocular video sequences. We extend the proposed shape-to-landmarks fitting to multiple frames by using the knowledge that all images are from the same identity. To recover facial texture, the approach uses texture from the original images, instead of employing the often-used PCA albedo model of a 3DMM. We employ an algorithm that merges texture from multiple frames in real-time based on a weighting of each triangle of the reconstructed shape mesh.
Last, we make the proposed real-time 3D morphable face model fitting algorithm available as open-source software. In contrast to ubiquitous available 2D-based face models and code, there is a general lack of software for 3D morphable face model fitting, hindering a widespread adoption. The library thus constitutes a significant contribution to the community.
We present a fully automatic approach to real-time 3D face reconstruction from monocular in-the-wild videos. We use a 3D morphable face model to obtain a semi-dense shape and combine it with a fast median-based super-resolution technique to obtain a high-fidelity textured 3D face model. Our system does not need prior training and is designed to work in uncontrolled scenarios.
We present a fully automatic approach to real-time 3D face reconstruction from monocular in-the-wild videos. With the use of a cascaded-regressor-based face tracking and a 3D morphable face model shape fitting, we obtain a semidense 3D face shape. We further use the texture information from multiple frames to build a holistic 3D face representation from the video footage. Our system is able to capture facial expressions and does not require any person specific training. We demonstrate the robustness of our approach on the challenging 300 Videos in the Wild (300- VW) dataset. Our real-time fitting framework is available as an open-source library at http://4dface.org.
In this work we investigate the behavior of MIS- and Schottky-gate AlGaN/GaN HEMTs under high-power pulsestress. A special setup capable of applying pulses of constant power is used to evaluate the electro-thermal response in different operating points. For both types of devices, the time to failure was found to decrease with increasing drain-source voltage. Overall, the Schottky-gate device displays a higher pulse robustness. The pulse withstand time of the MIS-gate device is limited by the occurrence of a thermal instability at approximately 240°C while the Schottky-gate device displays a rapid increase of the gate leakage current prior to failure. The mechanism responsible for this gate current is further investigated by static and transient temperature measurements and yielded activation energies of 0.6 eV and 0.84 eV.
Innovative Antriebstechnik muss die aktuellen Anforderungen und die spezifischen Anwenderwünsche mit den verfügbaren technologischen Möglichkeiten in hocheffiziente Lösungen umsetzen. Dazu müssen Elektronik, Software und Mechanik von der Berechnung bis zur Ausführung passgenau integriert und optimiert sein, um auch die heutigen ökonomischen und ökologischen Ansprüche an moderne Antriebe zu erfüllen.
Matthias Varga von Kibéd und Insa Sparrer unterscheiden zwischen drei verschiedenen Aufstellungsmethoden (Sparrer und Varga von Kibéd, o. D.): Der spezifisch (konkreten), der virtuellen und der prototypischen Aufstellung. Bei spezifischen Aufstellungen wird ein konkretes Anliegen eines Klienten betrachtet. Im Gegensatz dazu, werden bei virtuellen Aufstellungen eine Übungsumgebung geschaffen. In dieser können Aufstellungstechniken und Interventionsmethoden geübt werden. Bei prototypischen Strukturaufstellungen werden Themen zusammengefasst, die mehrere Teilnehmer im Seminar berühren bzw. in deren Alltag immer wieder auftreten können. Dieses Thema wird wie eine spezifische Aufstellung bearbeitet jedoch ohne ein konkretes vorliegendes Anliegen. Beispiele für prototypische Strukturaufstellungen kommen aus vielen Bereichen z.B. dem Führungsalltag, Teamentwicklung, Konfliktmanagement, Gesprächsführung, Zeit‐ und Selbstmanagement.
Projektbasiertes Lernen (PBL) ist eine ideale Methode, um Studierenden an Hochschulen praktische Projektmanagement-Kompetenzen zu vermitteln. Selbst anspruchsvolle Projekte werden hierdurch möglich. Jedoch ist die Balance zwischen den angestrebten Lernzielen und der praktischen Projektdurchführung in der Hochschulpraxis herausfordernd. Mit Hilfe des ‚PBL-Gold Standards‘ lassen sich PBL-Projekte zielgerichtet entwerfen und auf Effektivität hinsichtlich der Lernziele überprüfen. Am Beispiel des Projekts ‚IP Plane‘ der Hochschule Reutlingen, dem Bau eines Motorflugzeugs durch Studierende, wird die praktische Umsetzung eines PBL-Projektes demonstriert.
For optimization of production processes and product quality, often knowledge of the factors influencing the process outcome is compulsory. Thus, process analytical technology (PAT) that allows deeper insight into the process and results in a mathematical description of the process behavior as a simple function based on the most important process factors can help to achieve higher production efficiency and quality. The present study aims at characterizing a well-known industrial process, the transesterification reaction of rapeseed oil with methanol to produce fatty acid methyl esters (FAME) for usage as biodiesel in a continuous micro reactor set-up. To this end, a design of experiment approach is applied, where the effects of two process factors, the molar ratio and the total flow rate of the reactants, are investigated. The optimized process target response is the FAME mass fraction in the purified nonpolar phase of the product as a measure of reaction yield. The quantification is performed using attenuated total reflection infrared spectroscopy in combination with partial least squares regression. The data retrieved during the conduction of the DoE experimental plan were used for statistical analysis. A non-linear model indicating a synergistic interaction between the studied factors describes the reactor behavior with a high coefficient of determination (R²) of 0.9608. Thus, we applied a PAT approach to generate further insight into this established industrial process.
Analog integrated circuit sizing is notoriously difficult to automate due to its complexity and scale; thus, it continues to heavily rely on human expert knowledge. This work presents a machine learning-based design automation methodology comprising pre-defined building blocks such as current mirrors or differential pairs and pre-computed look-up tables for electrical characteristics of primitive devices. Modeling the behavior of primitive devices around the operating point with neural networks combines the speed of equation-based methods with the accuracy of simulation-based approaches and, thereby, brings quality of life improvements for analog circuit designers using the gm/Id method. Extending this procedural automation method for human design experts, we present a fully autonomous sizing approach. Related work shows that the convergence properties of conventional optimization approaches improve significantly when acting in the electrical domain instead of the geometrical domain. We, therefore, formulate the circuit sizing task as a sequential decision-making problem in the alternative electrical design space. Our automation approach is based entirely on reinforcement learning, whereby abstract agents learn efficient design space navigation through interaction and without expert guidance. These agents’ learning behavior and performance are evaluated on circuits of varying complexity and different technologies, showing both the feasibility and portability of the work presented here.
We have seen that bionic optimization can be a powerful tool when applied to problems with non-trivial landscapes of goals and restrictions. This, in turn, led us to a discussion of useful methodologies for applying this optimization to real problems. On the other hand, it must be stated that each optimization is a time consuming process as soon as the problem expands beyond a small number of free parameters related to simple parabolic responses. Bionic optimization is not a quick approach to solving complex questions within short times. In some cases it has the potential to fail entirely, either by sticking to local maxima or by random exploration of the parameter space without finding any promising solutions. The following sections present some remarks on the efficiency and limitations users must be aware of. They aim to increase the knowledge base of using and encountering bionic optimization. But they should not discourage potential users from this promising field of powerful strategies to find good or even the best possible designs.
With the rapid development of globalization, the demand for translation between different languages is also increasing. Although pre-training has achieved excellent results in neural machine translation, the existing neural machine translation has almost no high-quality suitable for specific fields. Alignment information, so this paper proposes a pre-training neural machine translation with alignment information via optimal transport. First, this paper narrows the representation gap between different languages by using OTAP to generate domain-specific data for information alignment, and learns richer semantic information. Secondly, this paper proposes a lightweight model DR-Reformer, which uses Reformer as the backbone network, adds Dropout layers and Reduction layers, reduces model parameters without losing accuracy, and improves computational efficiency. Experiments on the Chinese and English datasets of AI Challenger 2018 and WMT-17 show that the proposed algorithm has better performance than existing algorithms.
Purpose
The purpose of this study is to examine private households’ preferences for service bundles in the German energy market.
Design/methodology/approach
This investigation is based on survey data collected from 3,663 customers of seven mainly municipal energy suppliers in the German energy market. The data set was analyzed via a binary logistic regression model to identify the most prospective customers and their preferences regarding bundles of energy services.
Findings
The results indicate that potential adopters of energy-related service bundles have greater prior knowledge about service bundles; place higher importance on simplified handling, flat rates and long price guarantees; prefer to purchase a service bundle from an energy supplier; live in urban areas and have a gas tariff; are both less likely to have a green electricity tariff and to support the German energy transition; have a greater intention to purchase a smart home product; are less likely to already be prosumers; and prefer customer centers and social media as communication channels with energy providers.
Practical implications
This paper offers several implications for decision-makers in developing marketing strategies for bundled offerings in a highly competitive energy market.
Originality/value
This paper contributes to the sparse research on service bundles in the energy sector, despite the growing interest of energy suppliers and consumers in this topic. It expands the research focusing on the telecommunications sector.
Die additive Fertigung hat sich in den vergangenen Jahren wesentlich weiter entwickelt. Dabei wurde die Prozesstechnologie, Anlagen und die Werkstoffe optimiert. Für die industrielle Anwendung auch bei größeren Stückzahlen in der flexiblen Fertigung fehlen noch automatisierte Lösungen für die gesamte Prozesskette. In diesem Beitrag werden Werkzeuge und Technologie für die Reinigung interner Strukturelemente dargestellt.
Um den Übergang von der Schule zur Hochschule zu erleichtern, brauchen Studierende technischer Fächer häufig eine Auffrischung ihrer Kenntnisse in Mathematik und Physik. Ein Online-Lernsystem für Physik kann Studierende bei der Beschäftigung mit physikalischen Inhalten unterstützen. Zudem kann ein Physik-Wissenstest Lücken im individuellen Wissensstand aufzeigen und zum Lernen der fehlenden Themen motivieren. Die Arbeitsgruppe "eLearning in der Physik" der Hochschulföderation Süd-West (HfSW) bestehend aus den baden-württembergischen Hochschulen Aalen, Esslingen, Heilbronn, Mannheim und Reutlingen hat einen Aufgabenpool von über 200 Physikaufgaben für Erstsemester erarbeitet. Sie stehen den Studierenden mit Lösungen in Lernmanagementsystemen zum Selbststudium und jetzt auch im "Zentralen Open Educational Resources Repositorium der Hochschulen in Baden-Württemberg" (ZOERR) zur Verfügung. In diesem Beitrag wird über den Einsatz der Online-Übungsaufgaben in 2020/2021 berichtet, über die Ergebnisse der Wissenstests und über die in der Corona-Zeit neu eingerichteten eTutorien.
In clothing e-commerce, the challenge of optimally recommending clothing that suits a user’s unique characteristics remains a pressing issue. Many platforms simply recommend best-selling or popular clothing, without taking into account important attributes like user’s face color, pupil color, face shape, age, etc. To solve this problem, this paper proposes a personalized clothing recommendation algorithm that incorporates the established 4-Season Color System and user-specific biological characteristics. Firstly, the attributes and colors of clothing are classified by Fnet network, that can learn disjoint label combinations and mitigate the issue of excessive labels. Secondly, on the basis of the 4-Season Color System, the user’s face color model is trained by combined MobileNetV3_DTL, which ensures the model’s generalization and improves the training speed. Thirdly, user’s face shape and age are divided into different categories by an Inception network. Finally, according to the users’ face color, age, face shape and other information, personalized clothing is recommended in a coarse-to-fine manner. Experiments on five datasets demonstrate that the algorithm proposed in this paper achieves state-of-the-art results.
With the continuous development of economy, consumers pay more attention to the demand for personalization clothing. However, the recommendation quality of the existing clothing recommendation system is not enough to meet the user’s needs. When browsing online clothing, facial expression is the salient information to understand the user’s preference. In this paper, we propose a novel method to automatically personalize clothing recommendation based on user emotional analysis. Firstly, the facial expression is classified by multiclass SVM. Next, the user’s multi-interest value is calculated using expression intensity that is obtained by hybrid RCNN. Finally, the multi-interest value is fused to carry out personalized recommendation. The experimental results show that the proposed method achieves a significant improvement over other algorithms.
The loss contribution of a 2.3kW synchronous GaN-HEMT boost converter for an input voltage of 250V and an output voltage of 500V was analyzed. A simulation model which consists of two parts is introduced. First, a physics-based model is used to determine the switching losses. Then, a system simulation is applied to calculate the losses of the specific elements. This approach allows a fast and accurate system evaluation as required for further system optimization.
In this work, a hard- and a zero-voltage turn-on switching converter are compared. Measurements were performed to verify the simulation model, showing a good agreement. A peak efficiency of 99% was achieved for an output power of 1.4kW. Even with an output power above 400W, it was possible to obtain a system efficiency exceeding 98 %.
We present the results of an extensive characterization of the performance and stability of a third-order continuous-time delta-sigma modulator with active coefficient error compensation. Using our previously published coefficient tuning technique, process variation induced R-C time-constant (TC) errors in the forward signal path can be compensated indirectly using continuously tunable DACs in the feedback path. To validate our technique experimentally with a range of real TC variations, we designed a modulator with discretely configurable integration capacitor arrays in a 0.35-μm CMOS process. We configured the capacitors of the fabricated device for a range of total TC variations from -28.4 % to +19.3 % and measured the signal-to-noise ratio (SNR) as a function of the input amplitude before and after compensating the variations electrically using the feedback DACs. The results show that our tuning technique is capable of restoring the desired nominal modulator performance over the entire parameter variation range, including the system’s nominal maximum stable amplitude (MSA).
While digital IC design is highly automated, analog circuits are still handcrafted in a time-consuming, manual fashion today. This paper introduces a novel Parameterized Circuit Description Scheme (PCDS) for the development of procedural analog schematic generators as parameterized circuits. Circuit designers themselves can use PCDS to create circuit automatisms which capture valuable expert knowledge, offer full topological flexibility, and enhance the re-use of well-established topologies. The generic PCDS concept has been successfully implemented and employed to create parameterized circuits for a broad range of use cases. The achieved results demonstrate the efficiency of our PCDS approach and the potential of parameterized circuits to increase automation in circuit design, also to benefit physical design by promoting the common schematic-driven-layout flow, and to enhance the applicability of circuit synthesis approaches.
Nowadays, the demand for a MEMS development/design kit (MDK) is even more in focus than ever before. In order to achieve a high quality and cost effectiveness in the development process for automotive and consumer applications, an advanced design flow for the MEMS (micro electro mechanical systems) element is urgently required. In this paper, such a development methodology and flow for parasitic extraction of active semiconductor devices is presented. The methodology considers geometrical extraction and links the electrically active pn junctions to SPICE standard library models and subsequently extracts the netlist. An example for a typical pressure sensor is presented and discussed. Finally, the results of the parasitic extraction are compared with fabricated devices in terms of accuracy and capability.
Ein praktikables Mittel zur Erhöhung des Automatisierungsgrads im analogen IC-Entwurf ist die Verwendung parametrisierter Zellen. Diese sogenannten pCells werden eingesetzt, um determinierte Layouts automatisch zu erzeugen, und zwar in der Regel für einzelne Bauelemente wie Transistoren oder Dioden. Der vorliegende Beitrag zeigt die Potenziale eines erweiterten pCell-Konzepts, mit dem determinierte Layouts als auch Schaltpläne für ganze Schaltungsmodule automatisch generiert werden können. Als Beispiel wird eine solche Modul-pCell für analoge Stromspiegel beschrieben, die nicht nur die Dimensionierung der Einzeltransistoren, sondern auch verschiedene Transistortypen, beliebige Spiegelverhältnisse und sogar mehrere Topologien sowie weitere Freiheitsgrade implementiert. Das dadurch erzielte Maß an Flexibilität erlaubt es, die zahlreichen schaltungstechnischen Varianten im Analogbereich abzudecken, die ansonsten oftmals Hürden für Automatisierungsansätze darstellen.
Socially interactive robots with human-like speech synthesis and recognition, coupled with humanoid appearance, are an important subject of robotics and artificial intelligence research. Modern solutions have matured enough to provide simple services to human users. To make the interaction with them as fast and intuitive as possible, researchers strive to create transparent interfaces close to human-human interaction. Because facial expressions play a central role in human-human communication, robot faces were implemented with varying degrees of human-likeness and expressiveness. We propose a way to implement a program that believably animates changing facial expressions and allows to influence them via inter-process communication based on an emotion model. This will can be used to create a screen based virtual face for a robotic system with an inviting appearance to stimulate users to seek interaction with the robot.
This study describes a non-contact measuring and parameter identification procedure designed to evaluate inhomogeneous stiffness and damping characteristics of the annular ligament in the physiological amplitude and frequency range without the application of large static external forces that can cause unnatural displacements of the stapes. To verify the procedure, measurements were first conducted on a steel beam. Then, measurements on an individual human cadaveric temporal bone sample were performed. The estimated results support the inhomogeneous stiffness and damping distribution of the annular ligament and are in a good agreement with the multiphoton microscopy results which show that the posterior-inferior corner of the stapes footplate is the stiffest region of the annular ligament. This method can potentially help to establish a correlation between stiffness and damping characteristics of the annular ligament and inertia properties of the stapes and, thus, help to reduce the number of independent parameters in the model-based hearing diagnosis.
In this article feedback linearization for control-affine nonlinear systems is extended to systems where linearization is not feasible in the complete state space by combining state feedback linearization and homotopy numerical continuation in subspaces of the phase space where feedback linearization fails. Starting from the conceptual simplicity of feedback linearization, this new method expands the scope of their applicability to irregular systems with poorly expressed relative degree. The method is illustrated on a simple SISO–system and by controlling the speed and the rotor flux linkage in a three phase induction machine.
AI-based prediction and recommender systems are widely used in various industry sectors. However, general acceptance of AI-enabled systems is still widely uninvestigated. Therefore, firstly we conducted a survey with 559 respondents. Findings suggested that AI-enabled systems should be fair, transparent, consider personality traits and perform tasks efficiently. Secondly, we developed a system for the Facial Beauty Prediction (FBP) benchmark that automatically evaluates facial attractiveness. As our previous experiments have proven, these results are usually highly correlated with human ratings. Consequently they also reflect human bias in annotations. An upcoming challenge for scientists is to provide training data and AI algorithms that can withstand distorted information. In this work, we introduce AntiDiscriminationNet (ADN), a superior attractiveness prediction network. We propose a new method to generate an unbiased convolutional neural network (CNN) to improve the fairn ess of machine learning in facial dataset. To train unbiased networks we generate synthetic images and weight training data for anti-discrimination assessments towards different ethnicities. Additionally, we introduce an approach with entropy penalty terms to reduce the bias of our CNN. Our research provides insights in how to train and build fair machine learning models for facial image analysis by minimising implicit biases. Our AntiDiscriminationNet finally outperforms all competitors in the FBP benchmark by achieving a Pearson correlation coefficient of PCC = 0.9601.
The vast majority of state-of-the-art integrated circuits are mixed-signal chips. While the design of the digital parts of the ICs is highly automated, the design of the analog circuitry is largely done manually; it is very time-consuming; and prone to error. Among the reasons generally listed for this is often the attitude of the analog designer. The fact is that many analog designers are convinced that human experience and intuition are needed for good analog design. This is why they distrust the automated synthesis tools. This observation is quite correct, but this is only a symptom of the real problem. This paper shows that this phenomenon is caused by very concrete technical (and thus very rational) issues. These issues lie in the mode of operation of the typical optimization processes employed for the synthesizing tasks. I will show that the dilemma that arises in analog design with these optimizers is the root cause of the low level of automation in analog design. The paper concludes with a review of proposals for automating analog design
In a digitally controlled slope shaping system, reliable detection of both voltage and current slope is required to enable a closed-loop control for various power switches independent of system parameters. In most state-of-the-art works, this is realized by monitoring the absolute voltage and current values. Better accuracy at lower DC power loss is achieved by sensing techniques for a reliable passive detection, which is achieved through avoiding DC paths from the high voltage network into the sensing network. Using a high-speed analog-to-digital converter, the whole waveform of the transient derivative can be stored digitally and prepared for a predictive cycle-by-cycle regulation, without requiring high-precision digital differentiation algorithms. To gain an accurate representation of the voltage and current derivative waveforms, system parasitics are investigated and classified in three sections: (1) component parasitics, which are identified by s-parameter measurements and extraction of equivalent circuit models, (2) PCB design issues related to the sensing circuit, and (3) interconnections between adjacent boards.
The contribution of this paper is an optimized sensing network on the basis of the experimental study supporting fast transition slopes up to 100 V/ns and 1 A/ns and beyond, making the sensing technique attractive for slope shaping of fast switching devices like modern generation IGBTs, CoolMOSTM and SiC mosfets. Measurements of the optimized dv/dt and di/dt setups are demonstrated for a hard switched IGBT power stage.
Die Zielsetzung des hier vorgestellten Projekts ist es, eine intelligente Steuerungsalgorithmik für Biogas-Blockheizkraftwerke (Biogas-BHKW) zu entwickeln und zu optimieren. Daran schließt sich eine Testphase an einer realen Biogasanlage an, an der die Algorithmik zu diesem Zweck in die Anlagensteuerung implementiert wird. Um beurteilen zu können inwieweit die Steuerungsalgorithmik einen Beitrag zur Entlastung von Stromnetzen leisten kann, wird für die Versuche neben dem elektrischen Bedarf des landwirtschaftlichen Betriebs, an dem die Anlage angesiedelt ist, zusätzlich die Residuallast des benachbarten Stromnetzes betrachtet. Diese basiert auf Daten vom nächstgelegenen Umspannwerk, die so skaliert werden, dass sie eine Siedlung repräsentieren, die von dem Biogas-BHKW der Anlage mitversorgt werden kann. Die Einbindung der Steuerungsalgorithmik in die Anlagensteuerung erfolgt über eine Kommunikationsstruktur mit einer Datenbank als zentraler Schnittstelle. Eine erste Versuchsreihe, bei der das Biogas-BHKW nach den Fahrplänen der intelligenten Steuerungsalgorithmik geregelt wird, zeigt vielversprechende Ergebnisse. Über die gesamte Versuchsreihe hinweg berechnet die Steuerungsalgorithmik zuverlässig neue Fahrpläne, die vom BHKW weitestgehend auch sehr gut umgesetzt werden. Zudem kann nachgewiesen werden, dass durch den Einsatz der Algorithmik das vorgelagerte Stromnetz entlastet wird.
Es wird das Ziel verfolgt, eine Möglichkeit für die sichere Wiederverwendbarkeit von Schaltungen aus der OTA-Schaltungsklasse bereitzustellen. Hierfür werden ausgewählte OTA-Schaltungstopologien für die "Copy-and-Paste"-Methode vorgestellt. Es wurde im industriellen Umfeld gezeigt, dass sie sich unter der Voraussetzung einer repräsentativen Topologieauswahl – vordimensioniert für den typischen Anwendungsbereich – schon in dieser Form für die Wiederverwendung eignen.
This paper presents a control strategy for optimal utilization of photovoltaic (PV) generated power in conjunction with an Energy Storage System (ESS). The ESS is specifically designed to be retrofitted into existing PV systems in an end-user application. It can be attached in parallel to the PV system and connects to existing DC/AC inverters. In particular, the study covers the impact such a modification has on the output power of existing PV panels. A distinct degradation of PV output power was found due to the different power characteristics of PV panel and ESS. To overcome such degradation a novel feedback system is proposed. The feedback system continuously modifies the power characteristic of the ESS to match the PV panel and thus achieves optimal power utilization. Impact on PV and power point tracking performance is analyzed. Simulation of the proposed system is performed in MATLAB/Simulink. The results are found to be satisfactory.
This paper discusses the optimal control problem for increasing the energy efficiency of induction machines in dynamic operation including field weakening regime. In an offline procedure optimal current and flux trajectories are determined such that the copper losses are minimized during transient operations. These trajectories are useful for a subsequent online implementation.
Online-Portal "MINTFabrik"
(2023)
Das browserbasierte Online-Portal "MINTFabrik" entstand im Zuge der Maßnahmen zur Minderung von Lernrückständen mit der Idee, eine Lücke zu schließen, die es oft bei großen Online-Brückenkursen gibt: Ein Mangel an Übungsaufgaben, die schnell zugänglich sind, einfach ausgesucht werden können und gut auf bestimmte Lehrveranstaltungen und deren Anforderungen zugeschnitten sind. Die Entwicklung erfolgte in einer Kooperation der Hochschule Reutlingen mit der Tübinger Softwarefirma "Let´s Make Sense GmbH". Das Portal verzichtet bewusst auf eine Lektionsstruktur und besteht ausschließlich aus einzelnen Lernbausteinen (Items), d.h. Video-Tutorials, VisuApps und Aufgaben, die über eine komfortable Suche mit Filtern erreichbar sind und direkt bearbeitet werden können. Ein besonderes Merkmal der MINTFabrik sind Mikrokurse, die von Lehrenden und Studierenden erstellt werden können. Das sind kleine Einheiten aus einigen wenigen Items, die beliebig miteinander kombinierbar sind.
In many automotive applications, repetitive selfheating is the most critical operation condition for LDMOS transistors in smart power ICs. This is attributed to thermomechanical stress in the on-chip metallization, which results from the different thermal expansion coefficients of the metal and the intermetal dielectric. After many cycles, the accumulated strain in the metallization can lead to short circuits, thus limiting the lifetime. Increasing the LDMOS size can help to lower peak temperatures and therefore to reduce the stress. The downside of this is a higher cost. Hence, it has been suggested to use resilient systems that monitor the LDMOS metallization and lower the stress once a certain level of degradation is reached. Then, lifetime requirements can be fulfilled without oversizing LDMOS transistors, even though a certain performance loss has to be accepted. For such systems, suitable sensors for metal degradation are required. This work proposes a floating metal line embedded in the LDMOS metallization. The suitability of this approach has been investigated experimentally by test structures and shown to be a promising candidate. The obtained results will be explained by means of numerical thermo-mechanical simulations.
On the influence of ground and substrate on the radiation characteristics of planar spiral antennas
(2022)
The unidirectional radiation of spiral antennas mounted on a substrate requires the presence of a ground plane. In this work, we successively illustrate the impact of dielectric material and ground plane on the key metrics of a planar equiangular spiral antenna (PESA). For this purpose, a PESA mounted on several substrates with different dielectric properties and thicknesses is modeled and simulated. We introduce the tertiary current flowing on spiral arms when backed by a ground plane.