A C++ Simulator Generator from Graphical Specifications

Many languages for computer systems simulation (like GPSS and CSim) use a stochastic model of systems with the provision of adding procedural code for those aspects of the system that cannot be captured easily by a stochastic model. However, they do not support the hierachical simulation of complex systems well. Complex computer systems may have to be simulated at various levels of abstraction in the interests of tractability: the flexibility of being able to freely move between the different levels of abstraction is very desirable. For example, in the area of computer architecture, one might have analytical models, detailed simulation models and trace-driven models. In addition, these languages do not have user-friendly interfaces for specification of the simulated system. In this paper, we discuss the design and implementation of a simulation package for hierachical simulation of non-real-time computer systems: a Simulator Generator from a Graphical System Specification (SIGGSYS}). A new language for system specification has been designed. In addition, the package has the following components: • A graphical user interface to aid specification of the system to be simulated. • A rear end that generates C++ code that implements a simulator for the specified system. • A complete object library along with the header files that implement a functionally complete set of C++ base classes which can be built upon. C++ has been chosen as the intermediate language so that the modeller can use its support for object oriented programming. © 1997 John Wiley & Sons, Ltd.     

A language for high-level description of adaptive web systems

Adaptive Web systems (AWS) are Web-based systems that can adapt their features such as, presentation, content, and structure, based on users’ behaviour and preferences, device capabilities, and environment attributes. A framework was developed in our research group to provide the necessary components and protocols for the development of adaptive Web systems; however, there were several issues and shortcomings (e.g. low productivity, lack of verification mechanisms, etc.) in using the framework that inspired the development of a domain-specific language for the framework. This paper focuses on the proposal, design, and implementation of AWL, the Adaptive Web Language, which is used to develop adaptive Web systems within our framework. Not only does AWL address the existing issues in the framework, but it also offers mechanisms to increase software quality attributes, especially, reusability. An example application named PENS (a personalized e-News system) is explained and implemented in AWL. AWL has been designed based on the analysis of the adaptive Web domain, having taken into account the principles of reuse-based software engineering (product-lines), domain-specific languages, and aspect-oriented programming. Specially, a novel design decision, inspired by aspect-oriented programming paradigm, allows separate specification of presentation features in an application from its adaptation features. The AWL’s design decisions and their benefits are explained.     

Collision: Modeling,simulation and identification of robotic manipulators interacting with environments

The performance of many robotic tasks depends greatly on their dynamic collision behavior. This article presents a simple method for modeling and simulating collision behavior in manipulators. The main goal in this task is to provide informative contact models. The proposed models encompasscollision attributes which comprise not only (local) contact surface properties but also structural properties of the environmental object and the manipulator. With this method, the entire dynamic and interactive motion of the manipulator with the environmental object can be simulated effectively. This is verified by our simulation results. To facilitate our investigation, a 2 DOF planar elbow manipulator with PD control is considered in the simulations as well as theoretical analysis. The simulation results are used to highlight the collision attributes which affect collision behavior and to study the effects of these attributes on the manipulator-work environment safety and performance. On the other hand, the reliable operation of intelligent robotic systems in unstructured environments requires the estimation of collision attributes before the prediction of the collision behavior can be completed. For this purpose, we introduce the notion ofcollision identification. The present paper introduces a framework for collision identification in robotic tasks. The proposed framework is based on Artificial Neural Networks (ANNs) and provides fast and relatively reliable identification of the collision attributes. The simulation results are used to generate training data for the set of ANNs. A modularized ANN-based architecture is also developed to reduce the training effort and to increase the accuracy of ANNs. The test results indicate the satisfactory performance of the proposed collision identification system.     

混合仿真语言规范中的高级本体论

混合仿真语言规范不仅要能够定义语言的语法,还要能够定义设计概念的语义规则。本体论能够为描述将语法和语义相结合的语言规范奠定基础。本文基于对混合系统的分析,提出了混合系统高级本体论HyHO,它包括在混合建模和仿真的不同领域都能通用的最基本的规范,主要包括时间、事件、状态等概念及其属性分析。通过HyHO能够研究混合系统的本质属性,确定先进仿真中混合系统的计算模型,以及模型的通用形式化方法,为混合仿真语言规范设计奠定了基础。     

On satisfiability, equivalence, and implication problems involvingconjunctive queries in database systems

Satisfiability, equivalence, and implication problems involving conjunctive queries are important and widely encountered problems in database management systems. These problems need to be efficiently and effectively solved. In this paper, we consider queries which are conjunctions of the inequalities of the form (X op C), (X op Y), and/or (X op Y+C), where X and Y are two attributes, C is a constant, and op ϵ {<, ⩽, =,≠, >, ⩾}. These types of inequalities are widely used in database systems, since the first type is a selection, the second type is a &thetas;-join, and the third type is a very popular clause in a deductive database system. The satisfiability, equivalence, and implication problems in the integer domain (for attributes and constants) have been shown to be NP-hard. However, we show that these problems can be solved efficiently in the real domain. The incorporation of the real domain is significant, because the real domain is practically and widely used in a database. Necessary and sufficient conditions and algorithms are presented. A novel concept of the “module closure” and a set of sound and complete axioms with respect to the “module closure” are also proposed to infer all correct and necessary inequalities from a given query. The proposed axioms generalize Ullman's axioms (1989) where queries only consist of &thetas;-joins     

Modeling discrete event scalable network systems

Scalability in simulation tools is one of the most important traits to measure performance of software. The reason is that today’s Internet is the main instance of a large-scale and highly complex system. Simulation of Internet-scale network systems has to be supported by any simulation tool. Despite this fact, many network simulators lacks support for building large models. In this work, in order to propose a new approach for scalability issue in network simulation tools, a network simulator is developed based on behavior of honeybees and high performance DEVS, modular and hierarchical system theoretic approach. A biologically-inspired discrete event modeling approach is described for studying networks’ scalability and performance traits. Since natural systems can offer important concepts for modeling network systems, key adaptive and emergent attributes of honeybees and their societal properties are incorporated into a set of simulation models that are developed using the discrete event system specification approach. Large-scale network models are simulated and evaluated to show the benefits of nature-inspired network models.     

A domain-independent statistical methodology for dialog management in spoken dialog systems

This paper proposes a domain-independent statistical methodology to develop dialog managers for spoken dialog systems. Our methodology employs a data-driven classification procedure to generate abstract representations of system turns taking into account the previous history of the dialog. A statistical framework is also introduced for the development and evaluation of dialog systems created using the methodology, which is based on a dialog simulation technique. The benefits and flexibility of the proposed methodology have been validated by developing statistical dialog managers for four spoken dialog systems of different complexity, designed for different languages (English, Italian, and Spanish) and application domains (from transactional to problem-solving tasks). The evaluation results show that the proposed methodology allows rapid development of new dialog managers as well as to explore new dialog strategies, which permit developing new enhanced versions of already existing systems.     

Deductive Synthesis of Numerical Simulation Programs from Networks of Algebraic and Ordinary Differential Equations

Scientists and engineers face recurring problems of constructing, testing and modifying numerical simulation programs. The process of coding and revising such simulators is extremely time-consuming, because they are almost always written in conventional programming languages. Scientists and engineers can therefore benefit from software that facilitates construction of programs for simulating physical systems. Our research adapts the methodology of deductive program synthesis to the problem of constructing numerical simulation codes. We have focused on simulators that can be represented as second order functional programs composed of numerical integration and root extraction routines. We have developed a system that uses first order Horn logic to synthesize numerical simulators built from these components. Our approach is based on two ideas: first, we axiomatize only the relationship between integration and differentiation. We neither attempt nor require a complete axiomatization of mathematical analysis. Second, our system uses a representation in which functions are reified as objects. Function objects are encoded as lambda expressions. Our knowledge base includes an axiomatization of term equality in the lambda calculus. It also includes axioms defining the semantics of numerical integration and root extraction routines. We use depth bounded SLD resolution to construct proofs and synthesize programs. Our system has successfully constructed numerical simulators for computational design of jet engine nozzles and sailing yachts, among others. Our results demonstrate that deductive synthesis techniques can be used to construct numerical simulation programs for realistic applications.     

Recovering structured data types from a legacy data model with overlays

Legacy systems are often written in programming languages that support arbitrary variable overlays. When migrating to modern languages, the data model must adhere to strict structuring rules, such as those associated with an object oriented data model, supporting classes, class attributes and inter-class relationships.In this paper, we deal with the problem of automatically transforming a data model which lacks structure and relies on the explicit layout of variables in memory as defined by programmers. We introduce an abstract syntax and a set of abstract rewrite rules to describe the proposed approach in a language neutral formalism. Then, we instantiate the approach for the proprietary programming language that was used to develop a large legacy system we are migrating to Java.     

信号与系统仿真通用框架的设计与实现

本文提出了信号与系统仿真的一个通用框架,该框架充分考虑了系统的可扩展性和可重用性,并用几个Java类对核心模块的一些关键算法进行了设计和封装。然后设计了采样定理仿真的实例。仿真结果表明,在这个框架的基础上实现的信号与系统仿真结构清晰,简单易行,效果显著。最后,进一步说明了框架的应用。     

Context free languages in biological systems

A set of definitions is proposed which places a dynamic model of growth and stabilization in biological systems in a formal language framework. The language of stable adult strings achievable in a system without cellular interactions is studied. It is shown that o if every string is considered to be a possible initial string in development, then the class of languages defined is properly included in the class of regular languages. However if, as is biologically reasonable, development can only start from strings drawn from a finite initial set, then the class of languages defined is exactly the class of context free languages.     

Knowledge-based environment for investigating multicomputer architectures

Multicomputers for massively parallel processing will eventually employ billions of processing elements, each of which will be capable of communicating with every other processing element. A knowledge-based modelling and simulation environment (KBMSE) for investigating such multicomputer architecture at a discrete-event system level is described. The KBMSE implements the discrete-event system specification (DEVS) formalism in an object-oriented programming system of Scheme (a dialect), which supports building models in a hierarchical, modular manner, a systems-oriented approach not possible in conventional simulation languages. The paper presents a framework for knowledge-based modelling and simulation by exemplifying modelling a hypercube multicomputer architecture in the KBMSE. The KBMSE has been tested on a variety of domains characterized by complex, hierarchical structures such as advanced multicomputer architectures, local area computer networks, intelligent multi-robot organizations, and biologically based life-support systems.     

作战运筹仿真实验系统设计探讨

为了实现运筹研究的科学评估和方案优化,考虑将实验方法引入到作战运筹的研究中来.运用计算机仿真的方法进行作战运筹实验,将有效地提高实验的可重复性和可信度.参照既成的作战模拟系统的构架,结合导弹作战本身的特点,并考虑到实验结果对运筹研究的反馈作用,对导弹作战运筹实验系统的构建进行了探讨.主要探讨了三类实验系统:面向体系运筹的攻防对抗类实验系统、面向规划运筹的方案评估类实验系统、面向战场运筹的态势推演类实验系统.根据三类实验系统的特点,提出了构架设计方案.对这些实验系统设计的探讨,是作战实验室建设的先期探索,为计算机仿真方法在军事运筹学中的应用提供了参考.     

Two-level grammars for data conversions

Heterogeneous computer systems that are interconnected in today's computer networks lack efficient, general-purpose translation facilities for remote data. The provision of such facilities is potentially quite costly since the format of remote data is a function of the attributes of the remote architectures, operating systems, and software applications that maintain the data. This paper introduces a novel translation technique that parameterizes the translation process according to these attributes. Its formal specification is based on environment grammars, parameterized two-level grammars that lend themselves to the specification of classes of data languages with similar structures. We present a formal definition of environment grammars, discuss properties that permit their efficient parsing, and describe a data parsing method based on these properties. Examples illustrate the use of environment grammars for two different types of data languages. The viability of this parameterized technique has been demonstrated by an operational translation subsystem for data of heterogeneous relational database management systems.     

Template languages for fault monitoring of timed discrete eventprocesses

This paper introduces a new framework for modeling discrete event processes. This framework, called condition templates, allows the modeling of processes in which both single-instance and multiple-instance behaviors are exhibited concurrently. A single-instance behavior corresponds to a trace from a single finite-state process, and a multiple-instance behavior corresponds to the timed interleavings of an unspecified number of identical processes operating at the same time. The template framework allows the modeling of correct operation for systems consisting of concurrent mixtures of both single and multiple-instance behaviors. This representation can then be used in online fault monitoring for confirming the correct operation of a system. We compare the class of timed languages representable by template models with classes of timed languages from timed automata models. It is shown that templates are able to model timed languages corresponding to single and multiple-instance behaviors and combinations thereof. Templates can thus represent languages that could not be represented or monitored using timed automata alone     

Weight computation of criteria in a decision-making problem by knowledge measure with intuitionistic fuzzy set and interval-valued intuitionistic fuzzy set

The aim of this study is to propose an objective method for determining weights of criteria (also called attributes) based on a new measure of intuitionistic fuzzy information, called knowledge measure, in a real-world multi-criteria decision-making problem under intuitionistic fuzzy and interval-valued intuitionistic fuzzy environment. To address this issue, we first analyze the existing entropy measures and show that their use in objective weight determination process may lead us to produce unreliable weights of criteria by citing appropriate examples. Then we analyze important properties of knowledge measure of intuitionistic fuzzy set (IFS) and also define knowledge measure for interval-valued intuitionistic fuzzy set. Then a new method to determine the weights of criteria is developed on the basis of knowledge measure where information about criteria weights is completely unknown and partly known. A real-life example is presented to illustrate the proposed weight determination method and a comparative analysis is carried out to indicate the practicality and effectiveness of knowledge-based weight-generation method under both intuitionistic fuzzy and interval-valued intuitionistic fuzzy environment. Finally, we formulate the axioms for knowledge measure associated with IFSs and we also propose families (classes) of knowledge measures.     

A probabilistic language formalism for stochastic discrete-eventsystems

The formalism of probabilistic languages has been introduced for modeling the qualitative behavior of stochastic discrete-event systems. A probabilistic language is a unit interval-valued map over the set of traces of the system satisfying certain consistency constraints. Regular language operators such as choice, concatenation, and Kleene-closure have been defined in the setting of probabilistic languages to allow modeling of complex systems in terms of simpler ones. The set of probabilistic languages is closed under such operators, thus forming an algebra. It also is a complete partial order under a natural ordering in which the operators are continuous. Hence, recursive equations can be solved in this algebra. This is alternatively derived by using the contraction mapping theorem on the set of probabilistic languages which is shown to be a complete metric space. The notion of regularity, i.e., finiteness of automata representation, of probabilistic languages has been defined and it is shown that regularity is preserved under choice, concatenation, and Kleene-closure. We show that this formalism is also useful in describing system performance measures such as completion time, reliability, etc., and present properties to aide their computation