Refine
Year of publication
Document Type
- Journal article (1244)
- Conference proceeding (1039)
- Book chapter (381)
- Book (223)
- Doctoral Thesis (54)
- Working Paper (38)
- Anthology (32)
- Report (25)
- Patent / Standard / Guidelines (24)
- Issue of a journal (19)
Is part of the Bibliography
- yes (3088) (remove)
Institute
- ESB Business School (1107)
- Informatik (875)
- Technik (509)
- Life Sciences (343)
- Texoversum (220)
- Zentrale Einrichtungen (16)
Publisher
- Springer (473)
- IEEE (252)
- Elsevier (243)
- Hochschule Reutlingen (191)
- MDPI (99)
- Wiley (72)
- Gesellschaft für Informatik e.V (69)
- Universität Tübingen (65)
- De Gruyter (60)
- VDE Verlag (48)
A MATLAB toolbox was developed both for teachers performing quick experimental demonstrations during lectures and for students practicing measurement and frequency analysis procedures. The conceptual purpose was to support fundamental acoustics courses with contents defined by the DEGA recommendation 102. All implemented functions and parameters are visible at once and quickly adjustable by a GUI without submenus. A user manual is provided with explanations of how to get started and how all implemented functions can be applied. The toolbox probably still contains bugs. All users are welcome to inform the author about their experiences and proposals for improvement. In future it is planned to convert "Acoustics" to the MATLAB app designer format as Mathworks announced GUIDE to be replaced. Useful extensions would be additional tabs containing animations of sound propagation phenomena or sound fields caused by different sources.
Real estate markets are known to fluctuate. The real estate market in Stuttgart, Germany, has been booming for more than a decade: square-meter price hit top levels and real estate agents claim that market prices will continue to increase. In this paper, we test this market understanding by developing and analyzing a system dynamics model that depicts the Stuttgart real estate market. Simulating the model explains oscillating behavior arising from significant time delays and endogenous feedback structures – and not necessarily oscillating interest rates, as market experts assume. Scenarios provide insights into the system's behavior reacting to changes exogenous to the model. The first scenario tests the market development under increasing interest rates. The other scenario deals with possible effects on the real estate market if the regional automotive economy suffers from intense competition with new market players entering with alternative fuel vehicles and new technologies. With a policy run we test market structure changes to eliminate cyclical effects. The paper confirms that the business cycle in the Stuttgart real estate market arises from within the system's underlying structure, thus emphasizing the importance of understanding feedback structures.
Weltweit und in Deutschland erreicht das Thema Inflation neue Höchststände in der Aufmerksamkeit (Google-Trends 2022). Nach einer vielbeachteten und millionenfach angesehenen Online-Weihnachtsvorlesung aus dem Jahre 2020 hat der Ökonomieprofessor Hans-Werner Sinn das Buch mit gleichnamigem Titel „Die wundersame Geldvermehrung“ veröffentlicht. Abermals könnte es dem Autor gelingen die politische Öffentlichkeit damit aufzurütteln.
Functionally impaired people have problems with choosing and finding the right clothing. So, they need help in their daily life to wash and manage the clothing. The goal of this work is to support the user by giving recommendations to choose the right clothing, to find the clothing and how to wash the clothing. The idea behind eKlarA is to generate a gateway based system that uses sensors to identify the clothing and their state in the clothing cycle. The clothing cycle consists of (one and more) closet, laundry basket and washing machine in one or several places. The gateway uses the information about the clothing, weather and calendar to support the user in the different steps of the clothing cycle. This allows to give more freedom to the functionally impaired people in their daily life.
Entrepreneurs and small and medium enterprises usually have issues on developing new prototypes, new ideas or testing new techniques. In order to help them, in the last years, academic Software Factories, a new concept of collaboration between universities and companies have been developed. Software Factories provide a unique environment for students and companies. Students benefit from the possibility of working in a real work environment learning how to apply the state of the art of the existing techniques and showing their skills to entrepreneurs. Companies benefit from the risk-free environment where they can develop new ideas, in a protected environment. Universities finally benefit from this setup as a perfect environment for empirical studies in industrial-like environment. In this paper, we present the network of academic Software Factories in Europe, showing how companies had already benefit from existing Software Factories and reporting success stories. The results of this paper can increase the network of the factories and help other universities and companies to setup similar environment to boost the local economy.
In daily life, people tend to use mental shortcuts to simplify and speed up their decision-making processes. A halo effect exists if the impression created by a dominant attribute influences how other attributes of an object or subject are judged. It involves a cognitive bias that leads to distorted assessments. However, the halo effect has barely been researched in a sports-related context, although it can substantially contribute to understanding how sport fans think and behave. The objective of this paper is to answer the question that is of interest for both theory and practice of sports marketing: Is there a halo effect in sports? Does the sporting success or failure of a professional soccer team radiate or even outshine other sports related and non-sports aspects and influence or distort how the club is perceived by its fans? Fans of six soccer clubs selected from the first German soccer league Bundesliga were interviewed. This paper presents the results of an empirical study based on a data set consisting of a total of 4,180 cases. The results of the analyses substantiate the distortion of the fans’ perception with regard to a very diverse range of aspects that is triggered by the sporting success or failure of their favorite club.
Im dritten Jahr der Rezession drehte sich in Mailand alles um die italienische Lebensart und um das Erbe der großen Designer. Die spektakulären Inszenierungen fehlten weitgehend auf der Messe und in den Schauräumen rund um die Via Durini, dafür hatte man sich auf das Produkt konzentriert. Wiederbelebung der Erfolgsmodelle, Überarbeitung in Material und Farbe, Fokus auf große Namen, das waren die Botschaften in Mailand. Eine menschlich existentielle Antwort auf die Krise der letzten Jahre, aber auch Hoffnung und Aufbruchsstimmung waren zu spüren. Die Eurozone erholt sich, politischer Neubeginn und selbstbewusste Kommunikation italienischer Kultur in Stil und Design, das waren die Botschaften, die die Messe und auch die Aussteller des "Fuorisalone" vermittelten.
Der Anspruch an Energieversorger wird wachsen: in Zukunft gewinnen vor allem Aufgaben wie die Entwicklung digitalisierter Produkte/Dienstleistungen sowie ökologische Aktivitäten an Relevanz. Dies zeigt die Hochschule Reutlingen in ihrer aktuellen Untersuchung unter Aufsichtsräten, Geschäftsführern und Führungskräften. Trotz der erwarteten Veränderungen: die Aufsichtsräte sind sich zwar ihrem Druck zu mehr Professionalisierung bewusst, scheinen aktuell aber nur mäßig für die künftigen Herausforderungen des Unternehmens gerüstet. Besonders relevant dabei: die Professionalisierung der Gremienarbeit in kommunalen EVU ermöglicht einen höheren wahrgenommenen Unternehmenserfolg. So die Studie des Reutlinger Energiezentrums and der Hochschule Reutlingen im Auftrag von fünf Unternehmen der Branche.
Stetiger Wandel macht auch vor dem Vertriebsprozess deutscher KMU nicht Halt. Evolutive Umwelteinflüsse sowie revolutionäres Handeln stehen im Zentrum eines Umbruchs im Vertrieb. Ergebnisse aus einem quantitativen Stimmungsbarometer deutscher KMU ermöglichen das Ableiten unternehmerischer Handlungsempfehlungen für Vertriebsorganisationen.
Today 40 Gbps is in development at IEEE 802.3bq over four pair balanced cabling. In this paper, we describe a transmission experiment of 25 Gbps enabling either a single pair transmission of 25 Gbps over a 30 meter balanced cabling channel, or a 100 Gbps transmission via a four-pair balanced channel. A scalable matrix modeling tool is introduced which allows the prediction of transmission characteristics of a channel taking mode conversion into account . We applied this tool to characterize PCB-channels including the magnetics and PCB for a four-pair 100 Gbps transmission. We evaluated prototype cables and connecting hardware for frequencies up to 2 GHz and beyond. Finally we investigated possible line encoding schemes and provide measurement results of a transmission over 30 m with a data rate of 25 Gbps per twisted pair.
Modern power transistors are able to switch at very high transition speed, which can cause EMC violations and overshoot. This is addressed by a gate driver with variable gate current, which is able to control the transition speed. The key idea is that the gate driver can influence the di/dt and dv/dt transition separately and optimize whichever transition promises the highest improvement while keeping switching losses low. To account for changes in the load current, supply voltage, etc., a control loop is required in the driver to ensure optimized switching. In this paper, an efficient control scheme for an automotive gate driver with variable output current capability is presented. The effectiveness of the control loop is demonstrated for a MOSFET bridge consisting of OptiMOS-T2™devices with a total gate charge of 39nC. This bridge setup shows dv/dt transitions between 50 to 1000ns, depending on driving current. The driver is able to switch between gate current levels of 1 to 500mA in 10/15ns (rising/falling transition). With the implemented control loop the driver is measured to significantly reduce the ringing and thereby reduce device stress and electromagnetic emissions while keeping switching losses 52% lower than with a constant current driver.
The 21st century: an era where emojis and hashtags find their way into every sentence, where taking selfies, live tweeting and mining bitcoin are the norm, and where Insta-culture dictates what we say and do. This is the era into which the digital native was born. With so many changes in every aspect of our lives, how is it that one of the most influential aspects, our education, has remained unchanged? Our education system not only fails to appeal to today’s students, but more importantly, it fails to equip them with the skills required in the 21st Century. It is thus of no surprise that industries feel graduates entering the workplace lack skills in critical thinking, problem solving and self-directed learning. AI, machine learning and big data: Tools and mechanisms we so eagerly incorporate to create smart factories yet are hesitant to use elsewhere. Gamification and games have shown great results in education and training; with most research suggesting a stronger focus on personalization and adaptation. When combined with analytics and machine learning, the potential of games is yet to be realized. A real-time adaptive game would not only always present an appropriate degree of challenge for the individual but would allow for a shift in focus from the recitation of facts, to the application of information filtered to solve the particular problem at hand. South Africa, a country faced with a severe skills gap, could benefit greatly from games. If used correctly, they may just offer a desperately needed contribution toward equipping both current and future employees with the skills needed to survive in the 21st century. This paper explores the feasibility of using such games for enhanced knowledge dissemination and the upskilling of the workforce.
Autonomous navigation is one of the main areas of research in mobile robots and intelligent connected vehicles. In this context, we are interested in presenting a general view on robotics, the progress of research, and advanced methods related to this field to improve autonomous robots’ localization. We seek to evaluate algorithms and techniques that give robots the ability to move safely and autonomously in a complex and dynamic environment. Under these constraints, we focused our work in the paper on a specific problem: to evaluate a simple, fast and light SLAM algorithm that can minimize localization errors. We presented and validated a FastSLAM 2.0 system combining scan matching and loop closure detection. To allow the robot to perceive the environment and detect objects, we have studied one of the best deep learning technique using convolutional neural networks (CNN). We validate our testing using the YOLOv3 algorithm.
Software and system development is complex and diverse, and a multitude of development approaches is used and combined with each other to address the manifold challenges companies face today. To study the current state of the practice and to build a sound understanding about the utility of different development approaches and their application to modern software system development, in 2016, we launched the HELENA initiative. This paper introduces the 2nd HELENA workshop and provides an overview of the current project state. In the workshop, six teams present initial findings from their regions, impulse talk are given, and further steps of the HELENA roadmap are discussed.
To date, special interest has been paid to composite scaffolds based on polymers enriched with hydroxyapatite (HA). However, the role of HA containing different trace elements such as silicate in the structure of a polymer scaffold has not yet been fully explored. Here, we report the potential use of silicate-containing hydroxyapatite (SiHA) microparticles and microparticle aggregates in the predominant range from 2.23 to 12.40 μm in combination with polycaprolactone (PCL) as a hybrid scaffold with randomly oriented and well-aligned microfibers for regeneration of bone tissue. Chemical and mechanical properties of the developed 3D scaffolds were investigated with XRD, FTIR, EDX and tensile testing. Furthermore, the internal structure and surface morphology of the scaffolds were analyzed using synchrotron X-ray μCT and SEM. Upon culturing human mesenchymal stem cells (hMSC) on PCL-SiHA scaffolds, we found that both SiHA inclusion and microfiber orientation affected cell adhesion. The best hMSCs viability was revealed at 10 day for the PCL-SiHA scaffolds with well-aligned structure (~82%). It is expected that novel hybrid scaffolds of PCL will improve tissue ingrowth in vivo due to hydrophilic SiHA microparticles in combination with randomly oriented and well-aligned PCL microfibers, which mimic the structure of extracellular matrix of bone tissue.
For a holistic assessment of the interaction between the human body and tight fitted clothing, it is necessary to consider the mechanical properties of the body. Default avatars in CAD software are usually solid and do not take this interaction into account. For this purpose, a solid avatar is converted to a deformable one by using the soft body physics implementation in the simulation program Blender. The fit of a 3D garment on both avatars are compared, which allows a first evaluation of the differences between these approaches.
Lehr- und Übungsbuch sowie Nachschlagewerk zur CAD-Software Creo Parametric und zu den Grundlagen der Produktdatenverwaltung mit Windchill. Vermittelt werden die Volumenmodellierung, die 3D Flächenmodellierung, die Blechmodellierung, die Baugruppen- und Zeichnungserstellung, das Erstellen von Animationen, die Definition und Anwendung kinematischer sowie dynamischer Analysen und die Definition von Baugruppen, die Konstruktionsvarianten "Top-Down" und "Bottom-Up" sowie die Organisation von Konstruktionsprojekten über Skelett Techniken.
Weiter werden die Grundlagen des Produktdatenmanagements im Konstruktionsbereich unter Windchill vermittelt. Alle Verfahren werden handlungsorientiert an einem weitgehend durchgehenden Modellierungsprojekt erarbeitet. Aufgrund des ausführlichen Inhalts- und Sachwortverzeichnisses sowie einer Vielzahl an Bildern ist das Buch als Grundlage für Vorlesungen, Schulungen oder Praktika und insbesondere auch zum Selbststudium sowie als Nachschlagewerk geeignet.
Lehrbuch zur CAD-Software Creo Parametric und zur Produktdatenverwaltung mit Windchill.
3D-Volumenmodellierung, 3D-Flächenmodellierung, Blechmodellierung, Baugruppen- und Zeichnungserstellung, Definition von Normteilen, Erstellen von Animationen und dynamischen Analysen.
Verfahren zum Umgang mit großen Baugruppen und zur flexiblen Modellierung, Konstruk-tionsvarianten "Top-Down" und "Bottom-Up", Organisation von Konstruktionsprojekten über Skeletttechnik.
Neu: Konstruktion von und mit Mehrkörperobjekten, Rahmenkonstruktion in der Profilumgebung (AFX), intelligente Verbindungen (IFX), Live Simulation und Generatives Design.
Viele Unternehmen befassen sich in jüngster Zeit mit der Nutzung von Social Media für die interne Kommunikation und Zusammenarbeit. So genannte Enterprise Social Networks bieten integrierte Plattformen mit Profilen, Blogs, Gruppen- und Kommentarfunktionen für die unternehmensinterne Anwendung. Sehr häufig sind damit umfangreiche Investitionen verbunden. Die Budgets werden im Kern für die IT verwendet, "weiche Faktoren" bleiben häufig außen vor. Ein schwerer Fehler, wie aktuelle Marktstudien zeigen. Etliche der ambitionierten Projekte drohen daher zu scheitern.
The digitization of factories will be a significant issue for the 2020s. New scenarios are emerging to increase the efficiency of production lines inside the factory, based on a new generation of robots’ collaborative functions. Manufacturers are moving towards data-driven ecosystems by leveraging product lifecycle data from connected goods. Energy-efficient communication schemes, as well as scalable data analytics, will support these various data collection scenarios. With augmented reality, new remote services are emerging that facilitate the efficient sharing of knowledge in the factory. Future communication solutions should generally ensure connectivity between the various production sites spread worldwide and new players in the value chain (e.g., suppliers, logistics) transparent, real-time, and secure. Industry 4.0 brings more intelligence and flexibility to production. Resulting in more lightweight equipment and, thus, offering better ergonomics. 5G will guarantee real-time transmissions with latencies of less than 1 ms. This will provide manufacturers with new possibilities to collect data and trigger actions automatically.
Hochschulabsolventen sind für Unternehmen eine der wichtigsten Quellen für die Nachwuchsrekrutierung. Doch wie erreichen Sie die jungen Studenten am Besten? Eine bloße Ausschreibung einer Stelle auf der Unternehmenswebseite reicht nicht mehr aus. Wir zeigen Ihnen, wie Sie bereits vor dem Bewerbungsprozess in der Lebenswirklichkeit (Relevant Set) der Studierenden präsent werden, um überhaupt als Arbeitgeber in Betracht gezogen zu werden.
More and more power electronics applications utilize GaN transistors as they enable higher switching frequencies in comparison to conventional Si devices. Faster switching shrinks down the size of passives and enables compact solutions in applications like renewable energy, electrical cars and home appliances. GaN transistors benefit from ~10× smaller gate charge QG and gate drive voltages in the range of typically 5V vs. ~15V for Si.
An integrated synchronous buck converter with a high resolution dead time control for input voltages up to 48V and 10MHz switching frequency is presented. The benefit of an enhanced dead time control at light loads to enable zero voltage switching at both the high-side and low-side switch at low output load is studied. This way, compact multi-MHz DCDC converters can be implemented at high efficiency over a wide load current range. The concept also eliminates body diode forward conduction losses and minimizes reverse recovery losses. A dead time resolution of 125 ps is realized by an 8-bit differential delay chain. A further efficiency enhancement by soft switching at the high-side switch at light load is achieved with a voltage boost of the switching node by dead time control in forced continuous conduction mode. The monolithic converter is implemented in an 180nm high-voltage BiCMOS technology. At V IN = 48V, V OUT = 5V, 50mA load, 10MHz switching frequency and 500 nH output inductance, the efficiency is measured to be increased by 14.4% compared to a conventional predictive dead time control. A peak efficiency of 80.9% is achieved at 12V input.
In recent years, significant progress has been made on switched-capacitor DC-DC 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 IoE, industrial and automotive applications, etc. Such applications need to be capable of handling widely varying input voltages of more than 10V, which requires a large amount of conversion ratios. The goal is to achieve a fine granularity with the least number of flying capacitors. In [1] an SC converter was introduced that achieves these goals at low input voltage VIN ≤ 2.5V. [2] shows good efficiency up to VIN = 8V while its conversion ratio is restricted to ≤1/2 with a limited, non-equidistant number of conversion steps. A particular challenge arises with increasing input voltage as several loss mechanisms like parasitic bottom-plate losses and gate-charge losses of high-voltage transistors become of significant influence. High input voltages require supporting circuits like level shifters, auxiliary supply rails etc., which allocate additional area and add losses [2-5]. The combination of both increasing voltage and conversion ratios (VCR) lowers the efficiency and the achievable output power of SC converters. [3] and [5] use external capacitors to enable higher output power, especially for higher VIN. However, this is contradictory to the goal of a fully integrated power supply.
The presented wide-Vin step-down converter introduces a parallel-resonant converter (PRC), comprising an integrated 5-bit capacitor array and a 300 nH resonant coil, placed in parallel to a conventional buck converter. Unlike conventional resonant concepts, the implemented soft-switching control eliminates input voltage dependent losses over a wide operating range. This ensures high efficiency across a wide range of Vin= 12-48V, 100-500mA load and 5V output at up to 15MHz switching frequency. The peak efficiency of the converter is 76.3 %. Thanks to the low output current ripple, the output capacitor can be as small as 50 nF, while the inductor tolerates a larger ESR, resulting in small component size. The proposed PRC architecture is also suitable for future power electronics applications using fast-switching GaN devices.
The power supply is one of the major challenges for applications like internet of things IoTs and smart home. The maintenance issue of batteries and the limited power level of energy harvesting is addressed by the integrated micro power supply presented in this paper. Connected to the 120/230 Vrms mains, which is one of the most reliable energy sources and anywhere indoor available, it provides a 3.3V DC output voltage. The micro power supply consists of a fully integrated ACDC and DCDC converter with one external low voltage SMD buffer capacitor. The micro power supply is fabricated in a low cost 0.35 μm 700 V CMOS technology and covers a die size of 7.7 mm². The use of only one external low voltage SMD capacitor, results in an extremely compact form factor. The ACDC is a direct coupled, full wave rectifier with a subsequent bipolar shunt regulator, which provides an output voltage around 17 V. The DCDC stage is a fully integrated 4:1 SC DCDC converter with an input voltage as high as 17 V and a peak efficiency of 45 %. The power supply achieves an overall output power of 3 mW, resulting in a power density of 390 μW/mm². This exceeds prior art by a factor of 11.
This paper presents an integrated synchronous buck converter for input voltages >12V with 10MHz switching frequency. The converter comprises a predictive dead time control with frequency compensated sampling of the switching node which does not require body diode forward conduction. A high dead time resolution of 125 ps is achieved by a differential delay chain with 8-bit resolution. This way, the efficiency of fast switching DCDC converters can be optimized by eliminating the body diode forward conduction losses, minimizing reverse recovery losses and by achieving zero voltage switching at turn off. The converter was implemented in a 180nm high-voltage BiCMOS technology. The power losses were measured to be reduced by 30%by the proposed dead time control, which results in a 6% efficiency increase at VOUT = 5V and 0.2A load. The peak efficiency is 81 %.
A 20 V, 8 MHz resonant DCDC converter with predictive control for 1 ns resolution soft-switching
(2015)
Fast switching power supplies allow to reduce the size and cost of external passive components. However, the capacitive switching losses of the power stage will increase and become the dominant part of the total losses. Therefore, resonant topologies are the known key to reduce the losses of the power stage. A power switch with an additional resonant circuit can be turned on under soft-switching conditions, ideally with zero-voltage-switching (ZVS). As conventional resonant converts are only efficient for a constant load, this paper presents a predictive regulation loop to approach soft-switching conditions under varying load and component tolerances. A sample and hold based detection circuit is utilized to control the turn-on of the power switch by a digital regulation. The proposed design was fabricated in a 180 nm high-voltage BiCMOS technology. The efficiency of the converter was measured to be increased by up to 16 % vs. worst case timing and by 13 % compared to a conventional hard-switching buck converter at 20 V input voltage and at approximately 8 MHz switching frequency.
DC-DC-converters are used in many different applications. Specifying the switching frequency is the most important parameter to calculate component costs and required space. Especially automotive applications of small brushed- or brushless dc-motors and the increasing number of DC-DC-converters have high requirements on the structual space (low box volume). This is of particular importance for automotive converters for the new 48 V board net. Multiplying the frequency by two will reduce the size of the power inductor by half at a given specification for output-voltage ripple. Smaller power inductors result in reduced losses due to smaller series resistance and parasitic capacitance. Furthermore a larger switching frequency decreases the size of the DC link capacitors. The circuit will get more idealized. However, as the switching losses increase with frequency, a DC-DC-converter can only benefit from these advantages if the switching behavior can be improved.
This paper presents an optimization method to increase switching slope and switching frequency of a 3.6 kW 3-phase step-up converter by separating the design and layout process into two parts. The first part is the power stage which carries the load current. It contains the power inductance and the drain-source-channel of the power MOSFETs. The second part is the driver circuit which contains the driver ICs, the gate resistor and the gate input impedance. While the switching slope was measured to be improved by 50 % , the switching time decreased by 20 %. Hence, the switching frequency of the step-up converter could be increased from 100 kHz to 200 kHz without loss increase. By mounting the driver ICs in a piggyback configuration in close proximity to the power stage, the parasitics could be further reduced significantly and 500 kHz switching frequency could be achieved with 97.5 % efficiency.
A 3D face modelling approach for pose-invariant face recognition in a human-robot environment
(2017)
Face analysis techniques have become a crucial component of human-machine interaction in the fields of assistive and humanoid robotics. However, the variations in head-pose that arise naturally in these environments are still a great challenge. In this paper, we present a real-time capable 3D face modelling framework for 2D in-the-wild images that is applicable for robotics. The fitting of the 3D Morphable Model is based exclusively on automatically detected landmarks. After fitting, the face can be corrected in pose and transformed back to a frontal 2D representation that is more suitable for face recognition. We conduct face recognition experiments with non-frontal images from the MUCT database and uncontrolled, in the wild images from the PaSC database, the most challenging face recognition database to date, showing an improved performance. Finally, we present our SCITOS G5 robot system, which incorporates our framework as a means of image pre-processing for face analysis.
A high-voltage replica based current sensor is presented, along with challenges and design techniques which are rarely discussed in literature so far. The performance is evaluated by detailed small signal and large signal analysis. By dedicated placing of high-voltage cascode devices, while keeping as many low-voltage devices as possible, a high gain-bandwidth product is achieved. A decoupling and biasing circuit is introduced which improves the response time of the current sensor at on/off transitions by a factor of five. The current sensor is implemented in a 180nm HV BiCMOS technology. The sensor achieves a DC loop gain of 83 dB and a gain-bandwidth product of 7 MHz. With the proposed techniques, the gain-bandwidth product is increased by a factor of six. The measurable current range is between 60mA and 1.5 A. The performance is demonstrated in a 500 kHz buck converter at an input voltage of 40V. The overall circuit concept is suitable for 100V and beyond, enabling high performance power management designs including switched mode power supplies and motor applications.
This paper presents a wide-Vin step-down parallel-resonant converter (PRC), comprising an integrated 5-bit capacitor array and a 300-nH resonant coil, placed in parallel to a conventional buck converter. Soft-switching resonant converters are beneficial for high-Vin multi-MHz converters to reduce dominant switching losses, enabling higher switching frequencies. The output filter inductor is optimized based on an empirical study of available inductors. The study shows that faster switching significantly reduces not only the inductor value but also volume, price, and even the inductor losses. In addition, unlike conventional resonant concepts, soft-switching control as part of the proposed PRC eliminates input voltage-dependent losses over a wide operating range, resulting in 76.3% peak efficiency. At Vin = 48 V, a loss reduction of 35% is achieved compared with the conventional buck converter. Adjusting an integrated capacitor array, and selecting the number of oscillation periods, keeps the switching frequency within a narrow range. This ensures high efficiency across a wide range of Vin = 12–48 V, 100–500-mA load, and 5-V output at up to 25-MHz switching frequency. Thanks to the low output current ripple, the output capacitor can be as small
as 50 nF.
Size and cost of a switched mode power supply can be reduced by increasing the switching frequency. The maximum switching frequency and the maximum input voltage range, respectively, is limited by the minimum propagated on-time pulse, which is mainly determined by the level shifter speed. At switching frequencies above 10 MHz, a voltage conversion with an input voltage range up to 50 V and output voltages below 5 V requires an on-time of a pulse width modulated signal of less than 5 ns. This cannot be achieved with conventional level shifters. This paper presents a level shifter circuit, which controls an NMOS power FET on a high-voltage domain up to 50 V. The level shifter was implemented as part of a DCDC converter in a 180 nm BiCMOS technology. Experimental results confirm a propagation delay of 5 ns and on-time pulses of less than 3 ns. An overlapping clamping structure with low parasitic capacitances in combination with a high-speed comparator makes the level shifter also very robust against large coupling currents during high-side transitions as fast as 20 V/ns, verified by measurements. Due to the high dv/dt, capacitive coupling currents can be two orders of magnitude larger than the actual signal current. Depending on the conversion ratio, the presented level shifter enables an increase of the switching frequency for multi-MHz converters towards 100 MHz. It supports high input voltages up to 50 V and it can be applied also to other high-speed applications.
The level shifter and the floating gate supply for high-side transistors are a major challenge in high-voltage DCDC converters. This paper presents a high speed and power-efficient level shifter for voltages of up to 50V, suitable for both PMOS and NMOS power FETs. A switching node falling edge detection allows both, a sensitive and safe signal detection. This enables a robust operation during steep dv / dt transitions and a power consumption as low as 4.1 pJ per switching cycle, which is a reduction of more than 40% compared to prior art. An active clamping circuit prevents common mode displacement currents into the high-side supply. The level shifter is implemented in a 180nm BiCMOS technology. Measurements confirm a 50V 120MHz high-speed operation of the level shifter with a rising / falling propagation delay of 1.45 ns / 1.3 ns, respectively. The dv / dt robustness has been confirmed by measurements for transitions up to 6V/ ns.
A behavior marker for measuring non-technical skills of software professionals : an empirical study
(2015)
Managers recognize that software development teams need to be developed. Although technical skills are necessary, non-technical (NT) skills are equally, if not more, necessary for project success. Currently, there are no proven tools to measure the NT skills of software developers or software development teams. Behavioral markers (observable behaviors that have positive or negative impacts on individual or team performance) are successfully used by airline and medical industries to measure NT skill performance. This research developed and validated a behavior marker tool rated video clips of software development teams. The initial results show that the behavior marker tool can be reliably used with minimal training.
Managers recognize that software development project teams need to be developed and guided. Although technical skills are necessary, non-technical (NT) skills are equally, if not more, necessary for project success. Currently, there are no proven tools to measure the NT skills of software developers or software development teams. Behavioral markers (observable behaviors that have positive or negative impacts on individual or team performance) are beginning to be successfully used by airline and medical industries to measure NT skill performance. The purpose of this research is to develop and validate the behavior marker system tool that can be used by different managers or coaches to measure the NT skills of software development individuals and teams. This paper presents an empirical study conducted at the Software Factory where users of the behavior marker tool rated video clips of software development teams. The initial results show that the behavior marker tool can be reliably used with minimal training.
This paper presents a digitally controlled boost converter IC for high output voltage and fast transient applications. Thus, it is well applicable in automotive and industrial environments. The 3V-to-6V input voltage, 6.3V output voltage, 1A boost converter IC is fabricated in a 180nm BCD technology. Digital control enables cost savings, advanced control concepts, and it is less parameter sensitive compared to common analog control. A 90 ns latency, 6-bit delay line ADC operates with a window concept, meeting high resolution requirements, e.g. in car battery applications. An output voltage live tracking is included for extending the ADC conversion window. A charge pump DAC provides high resolution, monotonicity, and short 128 ns conversion time. Further, a standard digital PI controller is enhanced by a simple but effective ΔV/Δt-intervention control. It results in 2.8x reduced output voltage deviations in case of load steps, scaling down the output capacitor value by the same factor.
Academic research is vital for innovation and industrial growth. However, a potential burden of processing ever more knowledge could be affecting research output and researchers’ careers. We look at a dataset of researchers who have published in journals in the field of economics during a period of 45 years. For a subset of these researchers, we amass data from journals listed in the EconLit database, supplemented with years of birth from public sources. Our results show an increase in the age of researchers at their first publication, in the number of articles referenced in debut articles, and in the number of co-authors. Simultaneously, we observe a decline in the probability of researchers changing research fields. Our findings extend earlier findings on patents and hint at a burden of knowledge pervading different areas of human progress. Moreover, our results indicate that researchers develop strategies of specialisation to deal with this challenge.
How to protect the skin from getting sun burnt? The sun can damage your skin e.g. skin cancer. But the sun has a positive effect to the human. The time in sun and the intensity are key values between enjoy the sunbath and having a negative effect to the skin. A smart device like a UV flower could help you to enjoy the sunbath. It measures the UV index around you and gives this information to a smartphone app. The development steps of such a device are described in this paper. The UV flower is made of textile fabrics.
This article analyses and compares the performance of regulators in the fields of finance and sport, especially cycling. I hypothesize that the courses of crises or scandals is the best time to study the lessons of regulatory response. First, I take into account the differences in both finance and cycling by looking at the nature of the rules and institutions governing the field. Second, I estimate the attention effect on new regulation in response to crises or scandals. The interest of the paper is in the alignment of incentives to prevent regulatory capture and to ensure accountability and enforceability. The paper concludes that the differences hold important lessons that call for the reform of rules and institutions governing finance and cycling alike.
Artificial adipose tissue (AT) constructs are urgently needed to treat severe wounds, to replace removed tissue, or for the use as in vitro model to screen for potential drugs or study metabolic pathways. The clinical translation of products is mostly prevented by the absence of a vascular component that would allow a sustainable maintenance and an extension of the construct to a relevant size. With this study, we aimed to evaluate the suitability of a novel material based on bacterial cellulose (CBM) on the defined adipogenic differentiation of human adipose-derived stem cells (ASCs) and the maintenance of the received adipocytes (diffASCs) and human microvascular endothelial cells (mvECs) in mono- and coculture. A slight acceleration of adipogenic differentiation over regular tissue culture polystyrene (TCPS) was seen on CBM under defined conditions, whereas on the maintenance of the generated adipocytes, comparable effects were detected for both materials. CBM facilitated the formation of vascular like structures in monoculture of mvECs, which was not observed on TCPS. By contrast, vascular-like structures were detected in CBM and TCPS in coculture by the presence of diffASCs. Concluding, CBM represents a promising material in vascularized AT engineering with the potential to speed up and simplify the in vitro setup of engineered products.
Today’s cars are characterized by many functional variants. There are many reasons for the underlying variability, from the adaptation to diverse markets to different technical aspects, which are based on a cross platform reuse of software functions. Inevitably, this variability is reflected in the model-based automotive software development. A modeling language, which is widely used for modeling embedded software in the automotive industry, is MATLAB/Simulink. There are concepts facing the high demand for a systematic handling of variability in Simulinkmodels. However, not every concept is suitable for every automotive application. In order to present a classification of concepts for modeling variability in Simulink, this paper first has to determine the relevant use cases for variant handling in modelbased automotive software development. Existing concepts for modeling variability in Simulink will then be presented before being classified in relation to the previously determined use cases.
A closed-loop control for a cooperative innovation culture in interorganizational R&D projects
(2022)
Since project managers only have a limited authority in interorganizational R&D projects a cooperative innovation culture is essential for team cohesion and thus for achieving project scope in time and cost. For its development different factors depending on underlying values are essential. These factors must be learned iteratively by the project members so that they are living the values of a cooperative innovation culture. Hence, this paper raises the following research question: “How to control living the values of a cooperative innovation culture in interorganizational R&D projects?” To answer this question, a closed-loop control for a cooperative innovation culture is developed. The developed closed-loop control system includes several different functional units which show essential roles and several different variables which show what to consider and design in the control system. In addition, the developed closed-loop control system is generalized for other types of projects such as intraorganizational projects.