Abstractions of data types

The use of abstraction in the context of abstract data types, is investigated. Properties to be checked are formulas in a first order logic under Kleene's 3-valued interpretation. Abstractions are defined as pairs consisting of a congruence and a predicate interpretation. Three types of abstractions are considered,∀∀, ∀∃ and ∃^0,1∀, and for each of them corresponding property preservation results are established. An abstraction refinement property is also obtained. It shows how one can pass from an existing abstraction to a (less) finer one. Finally, equationally specified abstractions in the context of equationally specified abstract data types are discussed and exemplified.On leave from the Department of Computer Science, “Al. I. Cuza” University, Iaşi 740083, RomaniaThe research reported in this paper was partially supported by the program ECO-NET 08112WJ/2004-2005 and by the National University Research Council of Romania, grants CNCSIS 632(28)/2004 and CNCSIS 632(50)/2005.     

A predictive synchronizer for periodic clock domains

An adaptive predictive clock synchronizer for systems on chip incorporating multiple clock domains is presented. The synchronizer takes advantage of the periodic nature of clocks in order to predict potential conflicts in advance, and to conditionally employ an input sampling delay to avoid such conflicts. The result is conflict-free synchronization with maximal throughput and minimal latency. The adaptive predictive synchronizer adjusts automatically to a wide range of clock frequencies, regardless of whether the transmitter is faster or slower than the receiver. The synchronizer also avoids sampling duplicate data or missing any input. A novel method is presented for formal treatment of synchronizers and metastability. Correct operation of the synchronizer is formally proven and verified.     

简单非线性神经网络分类器及其在签名认证中的应用

该文分析了手写签名样本的特征值在特征空间上的分布。在此基础上,直接从神经元分类功能的物理意义出发,设计了具有非线性边界的,用于手写签名认证的神经网络分类器,妥善地解决了实际应用中,由于真实签名样本数量少和伪签名样本缺乏,不能训练神经网络的问题,取得了较好的认证结果。     

Comparison of Data from an IAQ Test House with Predictions of an IAQ Computer Model

One of the objectives of EPA's indoor air quality (IAQ) program is to provide guidance on the impact of indoor sources on IAQ. A computer model, EXPOSURE, was developed to assist in this effort. EXPOSURE calculates pollutant concentration as a function of time for each room of the building. EXPOSURE includes effects of sources, sinks, room-to-room air movement, and air exchange with the outdoors. Several experiments designed to evaluate the impact of indoor sources on IAQ are described. Measured concentrations are compared with concentrations predicted by an IAQ model. The measured concentrations are in excellent agreement with the predictions. The model predictions and the experimental data demonstrate the importance of sinks in determining long-term IAQ.     

高放废液玻璃固化工艺冷试验装置的设计和验证试验

设计、安装了一套玻璃固化冷试验装置,作了多轮工艺冷试验,取得了一定的经验。本文介绍了装置的设计参数和工艺冷试验对设备的考验结果。     

基于E-RBAC模型的通用用户权限配置的实现

传统的用户权限配置虽然有些采用RBAC模型,但都是针对具体业务系统,成为信息系统的一个功能模块,灵活性差,且缺乏通用性.为此,提出基于E-RBAC模型策略和应用Web技术,实现Web型信息系统中用户权限配置的通用性.     

A mini challenge: build a verifiable filesystem

We propose tackling a “mini challenge” problem: a nontrivial verification effort that can be completed in 2–3 years, and will help establish notational standards, common formats, and libraries of benchmarks that will be essential in order for the verification community to collaborate on meeting Hoare’s 15-year verification grand challenge. We believe that a suitable candidate for such a mini challenge is the development of a filesystem that is verifiably reliable and secure. The paper argues why we believe a filesystem is the right candidate for a mini challenge and describes a project in which we are building a small embedded filesystem for use with flash memory. The work described in this paper was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.     

基于CMMI验证工具的研究与设计

按照一定的过程生产产品并不能保证一定没有缺陷，所以需要增加生产过程中的检验措施，这就是质量控制。质量控制根据参照标准不同会有两种类型：验证和确认，简称V＆V。本文介绍了实施CMMI3级验证过程的支持框架及工具的设计。     

Refinement preserving approximations for the design and verification of heterogeneous systems

Embedded systems are electronic devices that function in the context of a real environment, by sensing and reacting to a set of stimuli. Because of their close interaction with the environment, and to simplify their design, different parts of an embedded system are best described using different notations and different techniques. In this case, we say that the system is heterogeneous. We informally refer to the notation and the rules that are used to specify and verify the elements of heterogeneous systems and their collective behavior as a model of computation. In this paper, we consider different classes of relationships between models of computation and discuss their preservation properties with respect to the model's refinement relation and composition operator. In particular, we focus on abstraction and refinement relationships in the form of abstract interpretations and introduce the notion of conservative approximation. We show that, unlike abstract interpretations, conservative approximations preserve refinement verification results from an abstract to a concrete model while avoiding false positives. We also characterize the relationship between abstract interpretations and conservative approximations, and derive necessary and sufficient conditions to obtain a conservative approximation from a pair of abstract interpretations. In addition, we use the inverse of a conservative approximation to identify components that can be used indifferently in several models, thus enabling reuse across models of computation. The concepts described in this paper are illustrated with examples from continuous time and discrete time models of computation.     

Automated Verification of Completeness and Consistency of Abstract State Machine Specifications using a SAT Solver

In the requirements engineering community, consistency and completeness have been identified as important properties of system specifications. Custom algorithms to verify these properties automatically have been devised for a number of specification languages, including SCR, RSML, and Statecharts. In this paper, we provide means to automatically verify completeness and consistency of Abstract State Machine (ASM) specifications. The verification is performed using a widely available tool, a SAT solver. The use of a SAT solver removes the need for designing and fine tuning language specific verification algorithms. Furthermore, the use of a SAT solver automates the verification procedure and produces a counterexample automatically when a specification is incomplete or inconsistent. We provide an algorithm to translate ASM specifications to a SAT problem instance. The translation is illustrated using the TASM toolset in conjunction with the “production cell system” case study.