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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.
Nenne sie niemals Senioren!
(2017)
In times of dynamic markets, enterprises have to be agile to be able to quickly react to market influences. Due to the increasing digitization of products, the enterprise IT often is affected when business models change. Enterprise Architecture Management (EAM) targets a holistic view of the enterprise’ IT and their relations to the business. However, Enterprise Architectures (EA) are complex structures consisting of many layers, artifacts and relationships between them. Thus, analyzing EA is a very complex task for stakeholders. Visualizations are common vehicles to support analysis. However, in practice visualization capabilities lack flexibility and interactivity. A solution to improve the support of stakeholders in analyzing EAs might be the application of visual analytics. Starting from a systematic literature review, this article investigates the features of visual analytics relevant for the context of EAM.
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.
It is assumed that more education leads to better understanding of complex systems. Some researchers, however, find indications that simple mechanisms like stocks and flows are not well understood even by people who have passed higher education. In this paper, we test people’s understanding of complex systems with the widely studied stock-and-flow (SF) tasks. SF tasks assess people’s understanding of the interplay between stocks and flows. We investigate SF failure of domain experts and novices in different knowledge domains. In particular, we compare performance on the original study’s bathtub task with the square wave pattern with two alternative cover stories from the engineering and business domains on different groups of business and engineering students from different semesters. Further, we show that, while engineering students perform better than business students, with progressing in higher education, students may lose the capability of dealing with simple SF tasks. We thus find hints on déformation professionelle in higher education.
Nowadays CHP units are discussed for the production of electricity on demand rather than for generation of heat providing electricity as a by-product. By this means, CHP units are capable of satisfying a higher share of the electricity demand on-site and in this new role, CHP units are able to reduce the load on the power grid and to compensate for high fluctuations of solar and wind power.
Evidently, a novel control strategy for CHP units is required in order to shift the operation oriented at the heat demand to an operation led by the electricity demand. Nevertheless, the heat generated by the CHP unit needs to be utilized completely in any case, for maintaining energy as well as economic efficiency. Such a strategy has been developed at Reutlingen University, and it will be presented in the paper. Part of the strategy is an intelligent management for the thermal energy storage (TES) ensuring that the storage is at low level in terms of its heat content just before an electricity demand is calling the CHP unit into operation. Moreover, a proper forecast of both, heat and electricity demand, is incorporated and the requirements of the CHP unit in terms of maintenance and lifetime are considered by limiting the number of starts and stops per unit time and by maintaining a certain minimum length of the operation intervals.
All aspects of this novel control strategy are revealed in the paper, which has been implemented on a controller for further testing at two sites in the field. Results from these tests are given as well as results from a simulation model, which is able to evaluate the performance of the control strategy for an entire year.
THE PROBLEM: Companies create problems for customers and employees when product innovation goes unmanaged. Eventually, excessive operational complexity hurts the bottom line.
THREE SOLUTIONS: Focus on product integration, not product proliferation. Make sure your product developers work closely with customerfacing and operational employees. And settle on a high-level purpose that can guide decision making.
This research is about Omnichannel Retailing and addresses the question how the omnichanneling of retailers in the fashion market can be measured. Our sources will include books, interviews, newspapers and scientific databases.
Omnichanneling is a current topic in the fashion market, retailers all over the world face the question on how to adapt to the challenges Omnichannel Retailing sets. We are going to define what Omnichanneling is by explaining the differences between Multiple-, Multi-, Cross- and Omnichannel Retailing. After we defined omnichanneling itself, we took a set of 26 retailers to evaluate regarding their Omnichannel capabilities. Then we create an index with criteria that can measure the Omnichannel capability of each retailer.
The Omnichannel Score is based on 31 criteria, which analyze the retailers in offline, online, mobile and social aspects enables to see differences between retailers. Our findings were that retailers in the US fashion market are more advanced in Omnichannel Retailing than retailers in the German fashion market. Our top three Omnichannel retailers were Sears with an Omnichannel Score of 91, followed by KOHL’S and Marks&Spencer, both with a Omnichannel Score of 88. The best Omnichannel Retailer from Germany was Adidas with the fourth place and an Omnichannel Score of 81.
There is no doubt that the amplification of channel integration towards an omni-channel structure is a powerful idea whose time has finally come. The digitally cross-linked world postulates all-encompassing, ubiquitous, and unobtrusive future services. In the concomitant, increasingly competitive market, retailers are starting to lay the foundation for omnichannel, meeting the expectations of a digitally cunning audience wanting their shopping experience to be as seamless and uncomplicated as possible. Nevertheless, recent researches show that there are still enough avenues for further research on omnichannel. Until now, the performance of companies was solely considered by experts from a suppliers’ point of view. It would be rather interesting to find out whether the desire to meet the increased cus-tomer expectations is also recognized by the customers themselves. This paper seeks to answering how the purchasing behavior has changed and what customers demand. In addition, it elaborates the opportunities that are promoted by omni-channel. Searching out all the effects, the paper will get to a final step, where it can be attested how the omnichannel performance of fashion and lifestyle retailers can be measured from a consumers’ perspective by developing an exclusive index. The study is confined to four fashion and lifestyle retailers: Hugo Boss AG, Levi Strauss & Co, Pull and Bear as well as COS. Using the scientific method of mystery shopping and a multi-item checklist including 54 key performance indicators, the paper aims to examine to which extend the four selected retailers provide a seamless customer journey, according to the five decision-making phases.
The purpose of this paper is to determine the relevance of social media for luxury brand management. It employs both a multi-methodological approach: After analyzing the online performance of the three luxury brands Burberry, Louis Vuitton and Gucci, the empirical research includes a survey as well as an eye tracking test executed with Tobii Studio. The findings reveal that online and social media have given luxury fashion businesses the opportunity to establish a sustainable interaction with their customers and distinguish themselves from the competition. Still, the online business holds many challenges for luxury companies to overcome. This paper gives instructions as to how social media can be effectively incorporated into a luxury company.
The conventional view of the value-creation chain suggests offering high-value propositions at the product level (in terms of benefits provided by elements of the product) to attain high-value perceptions at the customer level, which should ultimately result in high-value appropriation at the firm level (i.e. relationship, volume, pricing and financial success). This study challenges this view and provides a differentiated understanding of the value creation chain. With a multi-industry sample of 339 companies and a sample of 626 customers to validate managerial assessments, the authors apply a configurational approach to identify whether and to what extent offering high-value propositions at the product level is necessary or sufficient for achieving superior value perceptions at the customer level and high-value appropriation at the firm level. Taking into account the company-internal and company-external environment of the value-creation chain, the study identifies seven value creation chain constellations.
This work presents a spiral antenna array, which can be used in the V- and W-Band. An array equipped with Dolph-Chebychev coefficients is investigated to address issues related to the low gain and side lobe level of the radiating structure. The challenges encountered in this achievement are to provide an antenna that is not only good matched but also presents an appreciable effective bandwidth at the frequency bands of interest. Its radiation properties including the effective bandwidth and the gain are analyzed for the W-Band.
We present a topology of MIMO arrays of inductive antennas exhibiting inherent high crosstalk cancellation capabilities. A single layer PCB is etched into a 3-channels array of emitting/receiving antennas. Once coupled with another similar 3-channels emitter/receiver, we measured an Adjacent Channel Rejection Ratio (ACRR) as high as 70 dB from 150 Hz to 150 kHz. Another primitive device made out of copper wires wound around PVC tubes to form a 2-channels “non-contact slip-ring” exhibited 22 dB to 47 dB of ACRR up to 15MHz. In this paper we introduce the underlying theoretical model behind the crosstalk suppression capabilities of those so-called “Pie-Chart antennas”: an extension of the mutual inductance compensation method to higher number of channels using symmetries. We detail the simple iterative building process of those antennas, illustrate it with numerical analysis and evaluate there effectiveness via real experiments on the 3-channels PCB array and the 2-channels rotary array up to the limit of our test setup. The Pie Chart design is primarily intended as an alternative solution to costly electronic filters or cumbersome EM shields in wireless AND wired applications, but not exclusively.
Energy transfer kinetics in photosynthesis as an inspiration for improving organic solar cells
(2017)
Clues to designing highly efficient organic solar cells may lie in understanding the architecture of light harvesting systems and exciton energy transfer (EET) processes in very efficient photosynthetic organisms. Here, we compare the kinetics of excitation energy tunnelling from the intact phycobilisome (PBS) light harvesting antenna system to the reaction center in photosystem II in intact cells of the cyanobacterium Acaryochloris marina with the charge transfer after conversion of photons into photocurrent in vertically aligned carbon nanotube (va- CNT) organic solar cells with poly(3-hexyl)thiophene (P3HT) as the pigment. We find that the kinetics in electron hole creation following excitation at 600 nm in both PBS and va-CNT solar cells to be 450 and 500 fs, respectively. The EET process has a 3 and 14 ps pathway in the PBS, while in va-CNT solar cell devices, the charge trapping in the CNT takes 11 and 258 ps. We show that the main hindrance to efficiency of va CNT organic solar cells is the slow migration of the charges after exciton formation.
Digitisation forms a part of Industrie 4.0 and is both threatening, but also providing an opportunity to transform business as we know it; and can make entire business models redundant. Although companies might realise the need to digitise, many are unsure of how to start this digital transformation. This paper addresses the problems and challenges faced in digitisation, and develops a model for initialising digital transformation in enterprises. The model is based on a continuous improvement cycle, and also includes triggers for innovative and digital thinking within the enterprise. The model was successfully validated in the German service sector.
Propofol is a commonly used intravenous general anesthetic. Multi-capillary column (MCC) coupled ion-mobility spectrometry (IMS) can be used to quantify exhaled propofol, and thus estimate plasma drug concentration. Here, we present results of the calibration and analytical validation of a MCC/IMS pre-market prototype for propofol quantification in exhaled air.
In vitro cultured cells produce a complex extracellular matrix (ECM) that remains intact after decellularization. The biological complexity derived from the variety of distinct ECM molecules makes these matrices ideal candidates for biomaterials. Biomaterials with the ability to guide cell function are a topic of high interest in biomaterial development. However, these matrices lack specific addressable functional groups, which are often required for their use as a biomaterial. Due to the biological complexity of the cell-derived ECM, it is a challenge to incorporate such functional groups without affecting the integrity of the biomolecules within the ECM. The azide-alkyne cycloaddition (click reaction, Huisgen-reaction) is an efficient and specific ligation reaction that is known to be biocompatible when strained alkynes are used to avoid the use of copper (I) as a catalyst. In our work, the ubiquitous modification of a fibroblast cell-derived ECM with azides was achieved through metabolic oligosaccharide engineering by adding the azide-modified monosaccharide Ac4GalNAz (1,3,4,6 tetra-O-acetyl-N-azidoacetylgalactosamine) to the cell culture medium. The resulting azide-modified network remained intact after removing the cells by lysis and the molecular structure of the ECM proteins was unimpaired after a gentle homogenization process. The biological composition was characterized in order to show that the functionalization does not impair the complexity and integrity of the ECM. The azides within this ‘‘clickECM” could be accessed by small molecules (such as an alkyne modified fluorophore) or by surface-bound cyclooctynes to achieve a covalent coating with clickECM.
Purpose: The purpose of this study was to investigate the value of the web representation of certain fashion hot spots and how these results can be shown on fashion maps in an illustrated way.
Design/methodology/approach: A new ranking was created, which was evaluated with a self-instructed index, to gain solid results. Numbers were collected from Google, Instagram, Facebook, Twitter and web.alert.io. Additionally, fashion maps were created for an illustrative visualization of the results.
Findings: Compared with the ranking of a trend forecasting agency, called Global Language Monitor, which concepted a ranking of non-virtual fashion cities, the web representation and therefore the ranking of the research project, differs mainly in the situation of the cities among the first 10, viz. the rank on which a city occurs, but fewer in the actual cities mentioned.
Research limitations: The research was limited to subjective analysis of data, leading to partly subjective results, as well as the selected number of social media platforms, that had been used.
Originality/value: This is the first study to explore the web representation value of fashion metropolises in comparison to their non-virtual ranking. The results are partly based on results that already existed, concerning transformations of fashion cities or in general which cities own the status of a fashion city.
Purpose: The purpose of this paper is to examine the service of the new business model Curated Shopping in the fashion industry as well as to analyze if the service provides a higher costumer added value in comparison to traditional services in retail stores and e-commerce platforms. It gives implications to curated shop operators how to optimize the service in each stage of the customer buying process.
Design/methodology/approach: The research methodology applied is an empirical study that uses the principal of mystery shopping in order to investigate the provided services during the selling process.
Findings: The study showed that information about the customer should be collected carefully and as holistic as possible in order to assort a suitable outfit. The consumer is able to benefit from the service by saving time and enjoying a stress-free way of shopping. Nevertheless there are limitations in the personal service to give individual and inspiring advice by the curator caused by the physical distance to the customer.
Research limitations: The survey was conducted under 10 mystery shoppers and 4 curated shop operators in Germany, limiting findings to these mystery shoppers and operators.
Practical implications: One implication for the shop operators is to collect consumer information carefully and expand the assortment and brand portfolio in order to provide fashion goods to inspire the consumer. The shop operators are on the right track still there is huge potential to provide a more shopper-oriented service.