Modeling and experimental investigation for electrolytic corrosion prevention in high frequency micro EDM using deionized water

The characteristics of the prevention of electrolytic corrosion during micro electrical discharge machining (EDM) using deionized water and high frequency bipolar pulse were investigated. Electrolytic corrosion during micro EDM using deionized water was analyzed using an equivalent electrical circuit based on the electrical double layer theory. Based on the analysis and experimental verification, a narrow positive pulse duration should be provided to the workpiece to prevent corrosion. A negative voltage with zero average applied voltage (V_{avg, app}) is also essential for this purpose. If V_{avg, app} is positive or negative, electrolytic corrosion occurs on the workpiece or tool, respectively. Micro holes and 3D structures without corrosion were successfully fabricated using a high frequency bipolar pulse with a pulse duration of 0.2?μs and a period of 1?μs, as well as V_{avg, app}?=?0?V.     

Supervisory control synthesis of discrete-event systems using a coordination scheme

Supervisory control of distributed DES with a global specification and local supervisors is a difficult problem. For global specifications, the equivalent conditions for local control synthesis to equal global control synthesis may not be met. This paper formulates and solves a control synthesis problem for a generator with a global specification and with a combination of a coordinator and local controllers. Conditional controllability is proven to be an equivalent condition for the existence of such a coordinated controller. A procedure to compute the least restrictive solution within our coordination control architecture is provided and conditions under which the result coincides with the supremal controllable sublanguage are stated.     

A note on controllability of deterministic context-free systems

In this paper, we prove that the most important concept of supervisory control of discrete-event systems, the controllability property, is undecidable for two deterministic context-free languages $K$ and $L$, where $L$ is prefix closed, even though $K$ is a subset of $L$. If $K$ is not a subset of $L$, the undecidability follows from the work by Sreenivas. However, the case where $K$ is a subset of $L$ does not follow from that work because it is decidable whether $K$ and $L$ are equivalent as shown by Sénizergues. Thus, our result completes this study. The problem is also mentioned as open in the Ph.D. thesis by Griffin, who extended the supervisory control framework so that the specification language is modeled as a deterministic context-free language (compared to the classical approach where the specification is regular) and the plant language is regular. This approach is of interest because it brings an opportunity for more concise representations of the specification (as discussed, e.g., in the work by Geffert et al.) and, therefore, in some sense it treats the most interesting problem of current supervisory control theory, the state-space explosion problem.     

Influence of oxygen content on some properties of Nb3Sn tape used for superconducting transmission lines

The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO₂ substrate and/or Nb₃Sn tape superconductor prepared from such a substrate has been studied. The results have shown that the Nb₃Sn grains are much finer in the case of Nb-ZrO₂, than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200 %, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 cm and the relative elongation decreased from 5 to 3 %.     

Testing digital safety system software with a testability measure based on a software fault tree

Using predeveloped software, a digital safety system is designed that meets the quality standards of a safety system. To demonstrate the quality, the design process and operating history of the product are reviewed along with configuration management practices. The application software of the safety system is developed in accordance with the planned life cycle. Testing, which is a major phase that takes a significant time in the overall life cycle, can be optimized if the testability of the software can be evaluated. The proposed testability measure of the software is based on the entropy of the importance of basic statements and the failure probability from a software fault tree. To calculate testability, a fault tree is used in the analysis of a source code. With a quantitative measure of testability, testing can be optimized. The proposed testability can also be used to demonstrate whether the test cases based on uniform partitions, such as branch coverage criteria, result in homogeneous partitions that is known to be more effective than random testing. In this paper, the testability measure is calculated for the modules of a nuclear power plant's safety software. The module testing with branch coverage criteria required fewer test cases if the module has higher testability. The result shows that the testability measure can be used to evaluate whether partitions have homogeneous characteristics.     

Scalable Model of On-Wafer Interconnects for High-Speed CMOS ICs

This paper describes the development of an equivalent circuit model of on-wafer interconnects for high-speed CMOS integrated circuits. By strategically cascading two-pi blocks together, the lumped model can characterize the distributed effects. Besides, the elaborately proposed model characterizes the frequency-variant characteristics with frequency-independent components. Thus, the model can be easily plugged into commercial computer-aided design tools. By adopting a newly invented optimization algorithm, namely, particle swarm optimization (PSO), the model parameters are extracted and formulated as empirical expressions. Therein, with each set of the geometrical parameters, the interconnect behaviors can be accurately predicted. The accuracy of the model is validated by comparisons with the on-wafer measurements up to 30 GHz. Moreover, the scalability of the proposed model is also discussed     

Measuring Affective Clarity Indirectly: Individual Differences in Response Latencies of State.

This research investigated a new method to measure momentary affective clarity indirectly, which is based on latencies of responses to state affect items. Three studies revealed that this indirect measure of momentary clarity demonstrated high reliability and stability as well as convergent and predictive validity. The indirect measure was associated with dispositional clarity when the concept of clarity was activated before measuring response latencies (Studies 1 and 2) and was related to self-reports of momentary clarity (Study 3). Furthermore, Study 3 demonstrated that indirectly measured clarity decreased after an affectively complex film. Indirectly, but not directly, measured momentary clarity predicted a more positive affective state at the end of the study. This effect was mediated by affect regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Moderne Elektronenstrahltechnologien zum Fügen und zur Randschichtbehandlung. Modern Electron Beam Technologies for Soldering and Surface Treatment

A new generation of beam deflection technique is the basis for the development of electron beam (EB) technologies, which are not realisable with conventional methods. A high frequency 3D‐beam deflection makes possible multi‐field, multi‐pool and multi‐process technologies for EB welding und EB surface treatment, which result in a clear higher productivity and new combinations of properties.