Generating BDDs for symbolic model checking in CCS

Summary Finite transition systems can easily be represented by binary decision diagrams (BDDs) through the characteristic function of the transition relation. Burch et al. have shown how model checking of a powerful version of the -calculus can be performed on such BDDs. In this paper we show how a BDD can be generated from elementary finite transition systems given as BDDs by applying the CCS operations of parallel composition, restriction, and relabelling. The resulting BDDs only grow linearly in the number of parallel components. This way bisimilarity checking can be performed for processes out of the reach of conventional process algebra tools. Reinhard Enders graduated from the Technical University in Munich with a Diploma in mathematics and computer science in 1978. From 1977 to 1984 he was employed by Siemens, working in computer linguistics and expert systems. From 1984 to 1988 he worked at ECRC on Prolog extensions. In Autmn 1988 he joined Siemens and is developping the constraint extension of a new Prolog product. Thomas Filkorn received the computer science degree and the Ph.D. degree, both from the Technical University of Munich. Since 1992 he works at Siemens' Corporate Research and Development on symbolic algorithms and methods for the verification of finite state systems. Dirk Taubner received his Ph.D. in informatics at the Technical University of Munich in 1988. He investigated which sublanguages of process algebra could be represented finitely by automata and Petri nets. From 1989 through 91 he worked at Siemens' Corporate Research and Development where he led a project on computer-aided verification of parallel processes. This paper presents part of the work of that project. Currently he works on commercial software engineering for a software consulting company.     

Numerical modeling of coupled phenomena in a mechanically stirred molten-glass bath heated by induction

A mechanically stirred molten-glass bath heated by direct induction in a cold crucible was numerically modeled. The aim of the study was to develop numerical tools to understand thermal, hydrodynamic and electromagnetic phenomena that occur in the bath. Models and coupling between these phenomena are described. This coupling and the high content of elements in the 3D mesh result in a long calculation time. The study demonstrates how to couple programs to yield the highest degree of accuracy in the shortest calculation time possible. Numerical studies are also used to characterize the fluid dynamic behavior and heat transfer in an industrial-size tank. Classical correlations commonly used to characterize stirrer efficiency and heat transfer for fluids with constant physical properties were adapted for molten glass. The power number N_p and the Nusselt number Nu are used as macroscopic indicators. The results of these global studies will be useful for the operation and optimization of the vitrification facilities.     

标志性体育建筑与功能性体育建筑——回顾北京奥运中心区三大场馆的设计与建设

本文回顾了北京奥运中心区三大场馆的建设过程，提出“标志性体育建筑”与“功能性体育建筑”的概念，在阐述三大场馆产生的合理性与实践中取得成功的基础上对“尽善尽美”的宣传引导提出质疑，分析其中需改进的部分，并展望我国体育建筑的发展。     

A Study of Secure Multi-Party Elementary Function Computation Protocols

In this paper we consider three-party computations, study four operation problems of secure three-party and propose secure three-party four operations protocols. Secure three-party elementary function problems include exponential function problem, power function problem, logarithmic function problem, trigonometric function problem, and proposing a few concern protocols. The function is from four operations and compound functions, and we propose generalize method to conduct protocols. The motive of this paper is to present based on elementary function protocols for the application of secure multi-party computations.     

符号计算对计算有理矩阵指数的一种应用

在这篇文章中,我们探讨了符号计算对计算有理矩阵指数的一种应用,并在最后的数值例中得到了可行的结果．     

Differential invariants of a Lie group action: Syzygies on a generating set

Given a group action, known by its infinitesimal generators, we exhibit a complete set of syzygies on a generating set of differential invariants. For that we elaborate on the reinterpretation of Cartan’s moving frame by Fels and Olver [Fels, M., Olver, P.J., 1999. Moving coframes. II. Regularization and theoretical foundations. Acta Appl. Math. 55 (2), 127–208]. This provides constructive tools for exploring algebras of differential invariants.     

火炬塔架桩基础的设计

根据石化装置火炬塔架的特点,笔者结合沿海某工程的设计实例,从结构选型、荷载计算、地基处理、抗震构造等方面详细介绍火炬塔架的计算模型及其桩基础的设计要点。其中重点介绍了在高耸结构的基础中使用桩基础时应注意的设计问题。     

Concentration slip and its impact on heterogeneous combustion in a micro scale chemical reactor

The rarefied gas effect on concentration slip and on heterogeneous combustion in microscale chemical reactors was investigated. First, a concentration slip model to describe the rarefied gas effect on the species transport in microscale chemical reactors was derived from the approximate solution of the Boltzmann equation. Second, the model was verified using the direct Monte-Carlo method for the pure diffusion problems at different Knudsen numbers. The comparison showed that the present analytical model for the concentration slip boundary condition reasonably predicted the rarefied gas effect in the slip regime. Finally, the impact of the concentration slip on the coupling between the surface catalytic reactions and the homogeneous gas phase reactions in a microscale chemical reactor was examined using the one-step overall surface reaction model with a wide range of Knudsen and Damköhler numbers. It was shown that the rarefied gas effect significantly reduced the reaction rate of the surface catalytic oxidization for large Knudsen numbers. Furthermore, it was shown that the impact of slip effects on catalytic reactions strongly depends on the competition between the reaction rate and diffusion transport. It was found that the concentration slip causes a nonlinear reaction rate distribution at large Damköhler numbers. The results also showed that an accurate prediction of the rarefied gas effect on catalytic reactions in microscale reactors has to consider both the temperature slip and the concentration slip.     

Automating the DNA computer: solving n-Variable 3-SAT problems

In the decade since the first molecular computation was performed, it has been shown that DNA molecules can perform sophisticated, massively parallel computations avoiding the Von Neumann bottleneck. However, progress in the field has been slow. The largest problem solved to date is an instance of the 20-variable 3-CNF SAT problem. Performing the computation took more than two man-weeks to complete because every aspect of the computation was performed by hand. Molecular computations are extremely labor intensive and error prone–automation is necessary for further progress. The next step, (the second generation DNA computer—that of taking the laborious, laboratory bench protocols performed by hand, and automating them), has been achieved with the construction of an automated DNA computer dubbed EDNAC. It employs the same paradigm that was used to solve the labor-intensive instance of the 20-variable 3-CNF SAT problem. Using a combinatorial DNA library and complementary probes, EDNAC solves instances of the n-variable 3-CNF SAT problem. A 10 variable instance of the 3-CNF SAT problem was essayed. The computation took 28 h to perform. EDNAC correctly computed nine of the 10 variables, with a tenth variable remaining ambiguous. This result is comparable to current results in the molecular computation community. This research tested the critical properties, such as complexity, robustness, reliability, and repeatability necessary for the successful automation of a molecular computer.