Reliability of Solid State Switches Used in High Current Discharge Applications

The presentation will give information about the long term reliability of semiconductor components which are used in high current, high di/dt discharge switches as they are used in systems for electro-magnetic forming. Prototype equipment for laboratory use has shown the capability of the switches and equipment to fulfil the requirements requested by the end-users. This however is not enough to be used in the industrial production lines under continuous and repetitive heavy load conditions. Because of the relative high lifetime expectations of the durable equipment used for magnetic forming in the automotive industry the life-time of the semiconductor switches, the inductive loads and the capacitor banks are becoming an issue. The presentation will only describe the semiconductor reliability. A prototype system for 21 kVdc and pulse current of 210 kA was designed and built in the year 2005 by Siemens for the Fraunhofer Institute in Chemnitz, Germany. The semiconductor switch was supplied by ABB Switzerland Ltd. For this experimental machine only low repetition rates of one shot per several minutes and a limited expected life-time of approx. 15.000 20.000 shots was acceptable for the experimental work. The requirement from the automotive industry however is at least one shot per 15 seconds and an operational life-time of >= 2 Mio shot at the mentioned power level. During the last year ABB has done extensive tests to evaluate the behaviour of the semiconductor components used in high current solid state switches under the specific application conditions for production processes. In the presentation the test results of high current semiconductor devices are described for 250.000 shots and 1 Mio shots, and recommendations for reliable solid state switch designs are given. Keywords Semiconducto

Técnicas para el desarrollo de metamodelos aplicadas a problemas

Metamodels, also known as surrogate models, can be used in place of computationally expensive simulation models to increase computational efficiency for the purposes of design optimization or design space exploration. Metamodel-based design optimization is especially advantageous for ship design problems that require either computationally expensive simulations or costly physical experiments. In this paper, three metamodeling methods are evaluated with respect to their capabilities for modeling highly nonlinear, multimodal functions with incrementally increasing numbers of independent variables. Methods analyzed include kriging, radial basis functions (RBF), and support vector regression (SVR). Each metamodeling technique is used to model a set of single-output functions with dimensionality ranging from one to ten independent variables and modality ranging from one to twenty local maxima. The number of points used to train the models is increased until a predetermined error threshold is met. Results show that each of the three methods has its own distinct advantages.Los metamodelos, también conocimos como modelos substitutos, pueden ser utilizados en lugar de modeloscuyas simulaciones tienen un costo computacional muy alto, incrementado con esto la eficiencia en procesos de optimización de diseños o en el diseño de exploraciones espaciales. La optimización de diseños basados en metamodelos es especialmente ventajosa en problemas de diseño relacionado con vehículos marinos en los cuales serequieran simulaciones con un alto costo computacional o bien de experimentos con una alta inversión en equipos.En este artículo se evalúan tres métodos para el desarrollo de metamodelos. La evaluación de estos métodos es desarrollada teniendo en cuenta la capacidad de cada uno de ellos para modelar funciones multimodales no lineales con un número creciente de variables independientes. Dentro de los métodos analizados se encuentran el método de kriging, el método de funciones de base radiales, y el método de regresión con vector de apoyo. Cada una de las anteriores técnicas para la generación de metamodelos es utilizada para modelar un grupo de funciones de una salida con dimensiones variando desde uno hasta diez variables independientes y una modalidad variando entre uno y veinte máximos locales. El número de puntos utilizados para entrenar los modelos es incrementado hasta que el error alcanza una tolerancia predeterminada. Los resultados obtenidos muestran que cada uno de los tres modelos tiene sus propias ventajas distintivas

An Image-Analysis-Based Method for the Prediction of Recombinant Protein Fiber Tensile Strength

Silk fibers derived from the cocoon of silk moths and the wide range of silks produced by spiders exhibit an array of features, such as extraordinary tensile strength, elasticity, and adhesive properties. The functional features and mechanical properties can be derived from the structural composition and organization of the silk fibers. Artificial recombinant protein fibers based on engineered spider silk proteins have been successfully made previously and represent a promising way towards the large-scale production of fibers with predesigned features. However, for the production and use of protein fibers, there is a need for reliable objective quality control procedures that could be automated and that do not destroy the fibers in the process. Furthermore, there is still a lack of understanding the specifics of how the structural composition and organization relate to the ultimate function of silk-like fibers. In this study, we develop a new method for the categorization of protein fibers that enabled a highly accurate prediction of fiber tensile strength. Based on the use of a common light microscope equipped with polarizers together with image analysis for the precise determination of fiber morphology and optical properties, this represents an easy-to-use, objective non-destructive quality control process for protein fiber manufacturing and provides further insights into the link between the supramolecular organization and mechanical functionality of protein fibers

An Image-Analysis-Based Method for the Prediction of Recombinant Protein Fiber Tensile Strength

Silk fibers derived from the cocoon of silk moths and the wide range of silks produced by spiders exhibit an array of features, such as extraordinary tensile strength, elasticity, and adhesive properties. The functional features and mechanical properties can be derived from the structural composition and organization of the silk fibers. Artificial recombinant protein fibers based on engineered spider silk proteins have been successfully made previously and represent a promising way towards the large-scale production of fibers with predesigned features. However, for the production and use of protein fibers, there is a need for reliable objective quality control procedures that could be automated and that do not destroy the fibers in the process. Furthermore, there is still a lack of understanding the specifics of how the structural composition and organization relate to the ultimate function of silk-like fibers. In this study, we develop a new method for the categorization of protein fibers that enabled a highly accurate prediction of fiber tensile strength. Based on the use of a common light microscope equipped with polarizers together with image analysis for the precise determination of fiber morphology and optical properties, this represents an easy-to-use, objective non-destructive quality control process for protein fiber manufacturing and provides further insights into the link between the supramolecular organization and mechanical functionality of protein fibers

Properties of Biomimetic Artificial Spider Silk Fibers Tuned by PostSpin Bath Incubation

Efficient production of artificial spider silk fibers with properties that match its natural counterpart has still not been achieved. Recently, a biomimetic process for spinning recombinant spider silk proteins (spidroins) was presented, in which important molecular mechanisms involved in native spider silk spinning were recapitulated. However, drawbacks of these fibers included inferior mechanical properties and problems with low resistance to aqueous environments. In this work, we show that ≥5 h incubation of the fibers, in a collection bath of 500 mM NaAc and 200 mM NaCl, at pH 5 results in fibers that do not dissolve in water or phosphate buffered saline, which implies that the fibers can be used for applications that involve wet/humid conditions. Furthermore, incubation in the collection bath improved the strain at break and was associated with increased β-sheet content, but did not affect the fiber morphology. In summary, we present a simple way to improve artificial spider silk fiber strain at break and resistance to aqueous solvents

INTEROP deliverable DTG 6.2 : Method repository

This deliverable presents the INTEROP method chunks repository (MCR), its architecture and provided services. It includes the definition of a reusable method chunk, its structure, illustrated with examples of method chunks stored in the repository and guidelines for method chunks definition and characterisation covering tasks TG6.2 and TG6.3 of the work plan of the task group. The main result is the definition of the structure of the method chunk repository emphasizing the link to interoperability. Interoperability is a first-class concept in the structure of the method chunk repository. It not only characterizes method chunks, i.e. procedures to solve interoperability problems, but also interoperability cases, i.e. the presentation of actual problems involving interoperability issues. TG 6 has produced three MCR prototypes. Two experiments were undertaken using the Metis system and one using ConceptBase. The task group attended a two-day intense workshop on Metis. As a result, two experiments with Metis as platform for the method chunk repository are under way and reported in this deliverable. One is realizing the structure of the MCR as specified in this report. The other is an alternative approach that serves as a benchmark and is reported in the appendix. The ConceptBase prototype utilizes the metamodel presented in this deliverable. We have analysed three cases involving various aspects of interoperability. One case is about establishing a broker platform for insurance agents, the second about linking the information systems in the public utility sector, and the third case is establishing the relation of the ATHENA Model-Driven Interoperability Framework to the goals of the MCR. The results of the TG6 have been published at the ISD conference 2006 and the ER conference 2006. Copies of the papers are included in the appendix. The report of the example session with the method chunk repository has been shifted towards deliverable TG6.3 (Tutorial of the MCR). This is the more logical place. We want to emphasize that TG6 was not only busy in drafting concepts, exploring the state of the art, and analyzing cases. We are actually experimenting with a prototype and consider this a valuable contribution to the network. As soon as the prototype is stable, knowledge about interoperability solutions can be coded in this repository and can guide designers of interoperable systems by experience knowledge

Angle-Resolved Environmental X-Ray Photoelectron Spectroscopy: A New Laboratory Setup for Photoemission Studies at Pressures up to 0.4 Torr

The paper presents the development and demonstrates the capabilities of a new laboratory-based environmental X-ray photoelectron spectroscopy system incorporating an electrostatic lens and able to acquire spectra up to 0.4 Torr. The incorporation of a two-dimensional detector provides imaging capabilities and allows the acquisition of angle-resolved data in parallel mode over an angular range of 14° without tilting the sample. The sensitivity and energy resolution of the spectrometer have been investigated by analyzing a standard Ag foil both under high vacuum (10−8 Torr) conditions and at elevated pressures of N2 (0.4 Torr). The possibility of acquiring angle-resolved data at different pressures has been demonstrated by analyzing a silicon/silicon dioxide (Si/SiO2) sample. The collected angle-resolved spectra could be effectively used for the determination of the thickness of the native silicon oxide layer

Detection of New Delhi Metallo-β-Lactamase (Encoded by \u3ci\u3ebla\u3c/i\u3e\u3csub\u3eNDM-1\u3c/sub\u3e) in \u3ci\u3eAcinetobacter schindleri\u3c/i\u3e during Routine Surveillance

A carbapenem-resistant Alcaligenes faecalis strain was isolated from a surveillance swab of a service member injured in Afghanistan. The isolate was positive for blaNDM by real-time PCR. Species identification was reevaluated on three identification systems but was inconclusive. Genome sequencing indicated that the closest relative was Acinetobacter schindleri and that blaNDM-1 was carried on a plasmid that shared \u3e99% identity with one identified in an Acinetobacter lwoffii isolate. The isolate also carried a novel chromosomally encoded class D oxacillinase

SimSchool: An Opportunity for Using Serious Gaming for Training Teachers in Rural Areas

This article examines the use of simSchool as a training tool for educators working with students with special needs in rural districts. SimSchool is a game which emulates a classroom utilizing a virtual environment. The theory supporting simSchool is explored and current research associated with simSchool is reviewed. The issues surrounding retaining quality special educators in rural districts are discussed. The potential for using simSchool for working with rural special education teachers is explored