Distribution of a simple shared dataspace architecture

We study a simple software architecture, in which components are coordinated by writing into and reading from a global set. This simple architecture is inspired by the industrial software architecture Splice. We present two results. First, a distributed implementation of the architecture is given and proved correct formally. In the implementation, local sets are maintained and data items are exchanged between these local sets. Next we show that the architecture is sufficiently expressive in principle. In particular, every global specification of a system's behaviour can be divided into components, which coordinate by read and write primitives on a global set only. We heavily rely on recent concepts and proof methods from process algebra.     

Improved Distributed Algorithms for SCC Decomposition

We study and improve the OBF technique [Barnat, J. and P.Moravec, Parallel algorithms for finding SCCs in implicitly given graphs, in: Proceedings of the 5th International Workshop on Parallel and Distributed Methods in Verification (PDMC 2006), LNCS (2007)], which was used in distributed algorithms for the decomposition of a partitioned graph into its strongly connected components. In particular, we introduce a recursive variant of OBF and experimentally evaluate several different implementations of it that vary in the degree of parallelism. For the evaluation we used synthetic graphs with a few large components and graphs with many small components. We also experimented with graphs that arise as state spaces in real model checking applications. The experimental results are compared with that of other successful SCC decomposition techniques [Orzan, S., “On Distributed Verification and Verified Distribution,” Ph.D. thesis, Free University of Amsterdam (2004); Fleischer, L.K., B. Hendrickson and A. Pinar, On identifying strongly connected components in parallel, in: Parallel and Distributed Processing, IPDPS Workshops, Lecture Notes in Computer Science 1800, 2000, pp. 505–511].     

Thoughtful brute-force attack of the RERS 2012 and 2013 Challenges

The Rigorous Examination of Reactive Systems’ (rers) Challenges provide a forum for experimental evaluation based on specifically synthesized benchmark suites. In this paper, we report on our ‘brute-force attack’ of the rers 2012 and 2013 Challenges. We connected the rers problems to two state-of-the-art explicit state model checkers: LTSmin and Spin. Apart from an effective compression of the state vector, we did not analyze the source code of the problems. Our brute-force approach was successful: it won both editions of the rers Challenge.     

Introductory paper

This section is based on selected papers from the 6th and 7th ERCIM workshops on Formal Methods in Industrial Critical Systems. These papers either extend the state of the art in model checking and automatic test generation or they address the methodology for applying tools based on formal methods. Also, some important experiences are reported from industrial cases in which formal methods have been applied.     

WEEE和RoHS指令在工业上应用的前景

文章从生态效率应用的观点来考虑欧盟WEEE指令和RoHS指令的执行。荷兰代夫特技术大学从环境因素考虑，提出了环境权重的再循环理论。结合经济预算，提出了一种对电子产品生态效率全面的评价方式．通过这一方法可以评价WEEE指令如何可以取得最好的服务。此外，这一方法不但从生态设计和技术投资的角度，而且从系统的组织结构和制度的重要性上预示了回收和再循环系统将取得更大的进步。环境权重再循环／生态效率理论也在这个领域阐述了一种清晰的理念。对于RoHS指令，确定实施的时间窗口以及合适的系统边界和化学分析理论是成功的关键要素，这一问题将在放在一个单独的章节进行讨论。     

消费电子产品寿命终期的生态效益研究(三)

5.3.2中型塑料外壳产品 图14右边的三个点反映了普通传真机在采取不同回收方式情形下，环境性能和经济效益之间的变化情况。第一个箭头描述了未进行能量回收的焚烧过程与在焚烧过程中对残渣组分(包括产品中所有的塑料)进行能量回收的情况下，环境性能和经济效益之间的变化。第二个箭头描述了塑料再生利用与能量回收之间的变化。右边的两个箭头表明：与音响系统相比，中型塑料外壳的环境改善需要相对较高的单位重量成本。     

Symbolic PathFinder: integrating symbolic execution with model checking for Java bytecode analysis

Symbolic PathFinder (SPF) is a software analysis tool that combines symbolic execution with model checking for automated test case generation and error detection in Java bytecode programs. In SPF, programs are executed on symbolic inputs representing multiple concrete inputs and the values of program variables are represented by expressions over those symbolic inputs. Constraints over these expressions are generated from the analysis of different paths through the program. The constraints are solved with off-the-shelf solvers to determine path feasibility and to generate test inputs. Model checking is used to explore different symbolic program executions, to systematically handle aliasing in the input data structures, and to analyze the multithreading present in the code. SPF incorporates techniques for handling input data structures, strings, and native calls to external libraries, as well as for solving complex mathematical constraints. We describe the tool and its application at NASA, in academia, and in industry.     

Towards model checking executable UML specifications in mCRL2

We describe a translation of a subset of executable UML (xUML) into the process algebraic specification language mCRL2. This subset includes class diagrams with class generalisations, and state machines with signal and change events. The choice of these xUML constructs is dictated by their use in the modelling of railway interlocking systems. The long-term goal is to verify safety properties of interlockings modelled in xUML using the mCRL2 and LTSmin toolsets. Initial verification of an interlocking toy example demonstrates that the safety properties of model instances depend crucially on the run-to-completion assumptions.     

Development of an Apparatus for pH-Isolated Electrokinetic In Situ Chemical Oxidation

An apparatus was designed, manufactured, and implemented to isolate pH during electrokinetic in situ chemical oxidation (EK-ISCO). H+ and OH- electromigration were used to determine the adequacy of the designed apparatus for pH isolation. A series of pH-isolation and normal-mode (no pH-isolation) experiments were undertaken and compared. It was found that pH isolation was achieved when the electrode reservoirs were separated by porous media combined with the purging of the electrode reservoir fluid. The electromigration retardation factor of H+ and OH- was calculated for the porous media using the observed pH breakthrough times. The retardation factor for H+ was also calculated by considering mass flux data. The retardation factors for H+ and OH- were found to be 28.3 and 95, respectively, when using the breakthrough time. The retardation factor for H+ was calculated to be 36.7 using the mass flux data.     

A rewriting approach to binary decision diagrams

Binary decision diagrams (BDDs) provide an established technique for propositional formula manipulation. In this paper, we present the basic BDD theory by means of standard rewriting techniques. Since a BDD is a DAG instead of a tree we need a notion of shared rewriting and develop appropriate theory. A rewriting system is presented by which canonical reduced ordered BDDs (ROBDDs) can be obtained and for which uniqueness of ROBDD representation is proved. Next, an alternative rewriting system is presented, suitable for actually computing ROBDDs from formulas. For this rewriting system a layerwise strategy is defined, and it is proved that when replacing the classical apply-algorithm by layerwise rewriting, roughly the same complexity bound is reached as in the classical algorithm. Moreover, a layerwise innermost strategy is defined and it is proved that the full classical algorithm for computing ROBDDs can be replaced by layerwise innermost rewriting without essentially affecting the complexity. Finally a lazy strategy is proposed sometimes performing much better than the traditional algorithm.