Synthesizing structured analysis and object‐based formal specifications

Structured Analysis (SA) is a widely‐used software development method. SA specifications are based on Data Flow Diagrams (DFD's), Data Dictionaries (DD's) and Process Specifications (P‐Specs). As used in practice, SA specifications are not formal. Seemingly orthogonal approaches to specifications are those using formal, object‐based, abstract model specification languages, e.g., VDM, Z, Larch/C++ and SPECS. These languages support object‐based software development in that they are designed to specify abstract data types (ADT's). We suggest formalizing SA specifications by: (i) formally specifying flow value types as ADT's in DD's, (ii) formally specifying P‐Specs using both the assertional style of the aforementioned specification languages and ADT operations defined in DD's, and (iii) adopting a formal semantics for DFD “execution steps”. The resulting formalized SA specifications, DFD‐SPECS, are well‐suited to the specification of distributed or concurrent systems. We provide an example DFD‐SPEC for a client‐server system with a replicated server. When synthesized with our recent results in the direct execution of formal, model‐based specifications, DFD‐SPECS will also support the direct execution of specifications of concurrent or distributed systems.     

Applying Gaia and AUML for the development of multiagent‐based control software for flexible manufacturing systems: addressing methodological and implementation issues

In this article, we present the development of a simple multiagent‐based system for the control of a flexible manufacturing system. We followed the stages of a methodology specially conceived for the development of agent‐based system, which is an integration of the classical methodology for agent‐oriented analysis and design Gaia, and AUML (Agent‐Unified Modeling Language). We adopted as study case the CIMUBB Laboratory at the University of Bio‐Bio, which has a flexible manufacturing system including three flexible manufacturing cells interconnected by a conveyor belt. In the analysis stage, we identified roles involved, and we design models representing roles and protocols. In the design stage, we applied Gaia agent, services, and acquaintance models from Gaia, and we complemented with AUML as the adopted methodology suggests. With the developed models, we constructed a fully functional system where each agent was built as an independent process tree. Agents communicate by passing messages through the Ethernet network with socket interfaces. Various tests executed in our laboratory scale manufacturing system show the effectiveness of our implementation. Copyright © 2015 John Wiley & Sons, Ltd.     

Implementation of a constant‐time dynamic storage allocator

This paper describes the design criteria and implementation details of a dynamic storage allocator for real‐time systems. The main requirements that have to be considered when designing a new allocator are concerned with temporal and spatial constraints. The proposed algorithm, called TLSF (two‐level segregated fit), has an asymptotic constant cost, O(1), maintaining a fast response time (less than 200 processor instructions on a x86 processor) and a low level of memory usage (low fragmentation). TLSF uses two levels of segregated lists to arrange free memory blocks and an incomplete search policy. This policy is implemented with word‐size bitmaps and logical processor instructions. Therefore, TLSF can be categorized as a good‐fit allocator. The incomplete search policy is shown also to be a good policy in terms of fragmentation. The fragmentation caused by TLSF is slightly smaller (better) than that caused by best fit (which is one of the best allocators regarding memory fragmentation). In order to evaluate the proposed allocator, three analyses are presented in this paper. The first one is based on worst‐case scenarios. The second one provides a detailed consideration of the execution cost of the internal operations of the allocator and its fragmentation. The third analysis is a comparison with other well‐known allocators from the temporal (number of cycles and processor instructions) and spatial (fragmentation) points of view. In order to compare them, a task model has been presented. Copyright © 2007 John Wiley & Sons, Ltd.     

Assembly line balancing using genetic algorithms

Assembly Line Balancing (ALB) is one of the important problems of production/operations management area. As small improvements in the performance of the system can lead to significant monetary consequences, it is of utmost importance to develop practical solution procedures that yield high-quality design decisions with minimal computational requirements. Due to the NP-hard nature of the ALB problem, heuristics are generally used to solve real life problems. In this paper, we propose an efficient heuristic to solve the deterministic and single-model ALB problem. The proposed heuristic is a Genetic Algorithm (GA) with a special chromosome structure that is partitioned dynamically through the evolution process. Elitism is also implemented in the model by using some concepts of Simulated Annealing (SA). In this context, the proposed approach can be viewed as a unified framework which combines several new concepts of AI in the algorithmic design. Our computational experiments with the proposed algorithm indicate that it outperforms the existing heuristics on several test problems.     

Cognitive biases and decision support systems development: a design science approach

Abstract.  This paper presents design science research that aims to improve decision support systems (DSS) development in organizations. Evolutionary development has been central to DSS theory and practice for decades, but a significant problem for DSS analysts remains how to conceptualize the improvement of a decision task during evolutionary DSS development. The objective of a DSS project is to improve the decision process and outcome for a manager making an important decision. The DSS analyst needs to have a clear idea of the nature of the target decision task and a clear strategy of how to support the decision process. Existing psychological research was examined for help with the conceptualization problem, and the theory of cognitive bias is proposed as a candidate for this assistance. A taxonomy of 37 cognitive biases that codifies a complex area of psychological research is developed. The core of the project involves the construction of a design artefact – an evolutionary DSS development methodology that uses cognitive bias theory as a focusing construct, especially in its analysis cycles. The methodology is the major contribution of the project. The feasibility and effectiveness of the development methodology are evaluated in a participatory case study of a strategic DSS project where a managing director is supported in a decision about whether to close a division of a company.     

基于问题框架的行为驱动开发研究

问题框架(Problem Frames,PF)在需求工程研究领域中已经获得了广泛重视和研究。目前,问题框架的相关研究已经取得了较多成果,但如何从需求模型(问题图)平滑过渡到软件设计以及实现仍是一个有待解决的问题。文中对如何将问题图转换到用户场景文本以及通过用户场景来辅助行为驱动开发方法进行软件设计与开发进行了研究,提出了一种问题框架与行为驱动开发相结合的软件开发方法(PFBDD)。该方法能够帮助系统分析员将用户需求 平滑过渡 到软件设计及测试,从而避免软件项目中表达不一致带来的问题。此外,通过实例介绍了如何将此方法应用到一个车管业务排队系统中,并介绍了Gherkin语言和Specflow工具。该方法对于问题框架进一步走向实践具有重要的推动作用。     

基于MVC模式的WebGIS仿真系统

针对现有WebGIS开发效率不高、并发能力不强及服务器负载过重的问题,利用MVC设计模式在.NET开发平台中,建立了一个实用的WebGIS应用系统模型,并在此基础上进行了仿真。系统对WebGIS的客户端、服务器端进行了计算机仿真。系统具有显示的直观性与逼真性,而且具有很强的扩展性,可用于与WebGIS有关的教学与科研、实验分析。典型仿真实例及结果表明用MVC设计模式仿真WebGIS系统是方便和高效的。     

A method for design and performance modeling of client/server systems

Designing complex distributed client/server applications that meet performance requirements may prove extremely difficult in practice if software developers are not willing or do not have the time to help software performance analysts. The paper advocates the need to integrate both design and performance modeling activities so that one can help the other. We present a method developed and used by the authors in the design of a fairly large and complex client/server application. The method is based on a software performance engineering language developed by one of the authors. Use cases were developed and mapped to a performance modeling specification using the language. A compiler for the language generates an analytic performance model for the system. Service demand parameters at servers, storage boxes, and networks are derived by the compiler from the system specification. A detailed model of DBMS query optimizers allows the compiler to estimate the number of I/Os and CPU time for SQL statements. The paper concludes with some results of the application that prompted the development of the method and language.     

Situation awareness,human error,and organizational learning in sociotechnical systems

In many organizations, the performance of individuals and teams is negatively affected by human error. Studies have shown that these errors can be reduced or even prevented by learning from them and by developing an understanding of error causation and its consequences. The ability to detect, understand, and anticipate errors refers to situation awareness (SA). Although SA is not limited to human error and it is more closely linked with decision making, it is a prerequisite for error reduction in complex sociotechnical work settings. The main objectives of this study were threefold: First, a model that can explain the interrelations between human error, SA, and organizational learning in sociotechnical systems was developed. Secondly, functional and dysfunctional factors that affect human error, SA, and organizational learning were identified. Thirdly, a research methodology was selected and adapted to empirically test the model in a real‐world sociotechnical task environment. To do so, an SA performance test and a human error questionnaire were used to examine SA and respective learning modes of 108 assembly‐line workers in the manufacturing industry. The final test results supported the central assumptions of the applied model. The article concludes by discussing applications in the field of sociotechnical systems analysis, team training, human performance programs, and high‐reliability organizations.     

Reverse production system infrastructure design for electronic products in the state of Texas

Rapid technology advances have shortened the lifecycle of electronic products, resulting in the increasing number of discarded products in recent years. Due to the growing environmental concerns, several state governments have passed new regulations in order to reduce the amount of waste stream, to divert the discarded products from landfills, and to dispose the retired electronic products properly. As a result, an effective reverse logistics infrastructure is required to support the product recovery activities. In this paper, we propose a solution methodology for designing the infrastructure of the reverse production system by utilizing the mixed integer linear programming (MILP) model. A case study for designing the reverse production system in the state of Texas is also presented. Statistical analyses are carefully utilized to estimate design parameters in the case study from the available historical information from previous studies. Finally, discussions, recommendations, and insight information in designing and operating the reverse production system are presented.     

The concept of “stability” in asynchronous distributeddecision-making systems

Asynchronous distributed decision-making (ADDM) systems constitute a special class of distributed problems and are characterized as large, complex systems wherein the principal elements are the geographically dispersed entities that communicate among themselves, asynchronously, through message passing and are permitted autonomy in local decision making. Such systems generally offer significant advantages over the traditional, centralized algorithms in the form of concurrency, scalability, high throughput, efficiency, low vulnerability to catastrophic failures, and robustness. A fundamental property of ADDM systems is stability that refers to their behavior under representative perturbations to their operating environments, given that such systems are intended to be real, complex, and to some extent, mission-critical, and are subject to unexpected changes in their operating conditions. This paper introduces the concept of stability in ADDM systems and proposes an intuitive yet practical and usable definition that is inspired by those used in control systems and physics. An ADDM system is defined as a stable system if it returns to a steady state in finite time, following perturbation, provided that it is initiated in a steady state. Equilibrium or steady state is defined through placing bounds on the measured error in the system. Where the final steady state is equivalent to the initial one, a system is referred to as strongly stable. If the final steady state is potentially worse then the initial one, a system is deemed marginally stable. When a system fails to return to steady state following the perturbation, it is unstable. The perturbations are classified as either changes in the input pattern or changes in one or more environmental characteristics of the system, such as hardware failures. For a given ADDM system, the definitions are based on the performance indices that must be judiciously identified by the system architect and are likely to be unique. To facilitate the understanding of stability in representative real-world systems, this paper reports the analysis of two basic manifestations of ADDM systems that have been reported in the literature: (1) a decentralized military command and control problem, MFAD and (2) a novel distributed algorithm with soft reservation for efficient scheduling and congestion mitigation in railway networks, RYNSORD. Stability analysis of MFAD and RYNSORD yields key stable and unstable conditions. A system determined to be stable provides the reassurance that the system will perform well under adverse conditions. In contrast, a system deemed unstable reflects the need to address key weaknesses in the system design. Thus, stability analysis is a necessary and critical step in the development of any ADDM system.     

Complex service design: A virtual enterprise architecture for logistics service

This paper presents an interdisciplinary systems approach to service modeling, design and deployment. The study is based on a longitudinal case study of the development process of a complex logistic service system based on an advanced logistics model. The case examines the development of a Virtual Enterprise Architecture (VEA) for an automatic high-speed transport and sorting system applied in airports for baggage handling. The study traces the evolution of the system from the early conceptual phases to a successful commercial service deployed at Changi, Singapore Airport. The study is conducted using a retrospective analysis of the case using a design science research approach. The paper evaluates and discusses the issues of creating and designing a new complex logistics service, distinct from the physical product, based on an advanced discrete event-based simulation model. The paper concludes by presenting a generalized and validated conceptual framework for a VEA based on an advanced simulation model. The paper thus contributes to the field of service systems and service management by identifying a novel approach to effective design of a new service.     

WWW-based reliability information system

This paper discusses the reliability information system developed with the concept of world wide web (WWW) and client/server architecture. An existing server and client for the system are modified to perform HTTP duties and graphically advanced reliability analysis. The technical background and the relationship of the WWW and client/server system is explained. With the developed system, the design engineers and reliability analysts can analyze the reliability of the system more quickly and conveniently.     

An Internet-based intelligent design system for injection moulds

The rapid growth of Internet and information technologies in recent years provides a solution to support and facilitate collaborative product developments among different geographically distributed enterprises. An effective and feasible tool to aid the collaborative development of injection moulds can be realized by developing an Internet-based mould design system as one of the modules of a collaborative product development system. This paper presents a prototype Internet-based intelligent design system for injection moulds. The architecture of the system consists of an interactive KB mould design system embedded in an Internet environment. A Java-enabled solution together with artificial intelligence techniques is employed to develop such a networked interactive CAD system. In this system, the computational module, the knowledge base module and the graphic module for generating mould features are integrated within an interactive CAD-based framework. The knowledge base of the system would be accessed by mould designers through interactive programs so that their own intelligence and experience could also be incorporated with the total mould design. The approach adopted both speeds up the design process and facilitates design standardization which in turn increases the speed of mould manufacture. A practical case study is presented to illustrate the operations of the Internet-based mould design system.     

Robust Analytical Redundancy Relations for Fault Diagnosis In Nonlinear Systems

The problem of robust analytical redundancy relations design for fault diagnosis in nonlinear systems is investigated. An approach is proposed to solve this problem through an extension of the system state‐space by means of constant (or slow varying) unknown parameters, followed by designing analytical redundancy relations that are insensitive both to state variables and unknown parameters. To make the design practicable, some problems related to nonlinear transformation of the extended system model into observable one are considered. The quasi‐linear computational form for robust analytical redundancy relations is described. Fault detectability and distinguishability conditions are formulated, and a recommendation for choosing the size of the moving time window is made. The results are demonstrated through an example involving an SISO nonlinear model of an underwater vehicle.     

Reliable State Feedback Control Synthesis For Uncertain Linear Systems

This paper is concerned with the problem of designing reliable state‐ feedback control for a class of uncertain linear systems with norm bounded uncertainty. A procedure for designing reliable state‐feedback control is presented for the case of actuator faults that can be modeled by a scaling factor. In the design, the performance of the normal system (without fault) is optimized, as the considered system operates under the normal condition most of the time. In addition, when actuator faults occur, the closed‐loop system retains robust stability and satisfies a known quadratic performance bound. A numerical example is provided to illustrate the effectiveness of the proposed design method.     

Procedures in complex systems: the airline cockpit

In complex human-machine systems, successful operations depend on an elaborate set of procedures which are specified by the operational management of the organization. These procedures indicate to the human operator (in this case the pilot) the manner in which operational management intends to have various tasks done. The intent is to provide guidance to the pilots and to ensure a safe, logical, efficient, and predictable (standardized) means of carrying out the objectives of the job. However, procedures can become a hodge-podge. Inconsistent or illogical procedures may lead to noncompliance by operators. Based on a field study with three major airlines, the authors propose a model for procedure development called the “Four P's”: philosophy, policies, procedures, and practices. Using this model as a framework, the authors discuss the intricate issue of designing flight-deck procedures, and propose a conceptual approach for designing any set of procedures. The various factors, both external and internal to the cockpit, that must be considered for procedure design are presented. In particular, the paper addresses the development of procedures for automated cockpits-a decade-long, and highly controversial issue in commercial aviation. Although this paper is based on airline operations, we assume that the principles discussed here are also applicable to other high-risk supervisory control systems, such as space flight, manufacturing process control, nuclear power production, and military operations     

Event‐triggered PCS Based Trajectory Tracking Control of Systems with Perturbation

This paper is aimed at reducing network load for saving bandwidth by designing appropriate trigger signals that decide when the transmission should be done. An event‐triggered piecewise continuous systems (PCS) based control for time‐varying trajectory tracking is proposed. By designing the sensor system and controller system, the communication between them is reduced while still retaining a satisfactory closed‐loop behavior of the whole system. The major idea behind a designed sensor system is the use of a Luenberger observer and planning of event‐triggered mechanism (ETM). The main principle behind the designed controller system is the proposal of a new event‐triggered PCS based controller. The development is motivated by consideration of variable network induced time delays. Tracking error is proved to be norm‐bounded in both the original and developed case. Finally, to show the proposed method's performance, we present the simulation results for a mobile cart.     

Hybrid of simulated annealing and SVM for hydraulic valve characteristics prediction

Accurate prediction for the synthesis characteristics of hydraulic valve in industrial production plays an important role in decreasing the repair rate and the reject rate of the product. Recently, Support Vector Machine (SVM) as a highly effective mean of system modeling has been widely used for predicting. However, the important problem is how to choose the reasonable input parameters for SVM. In this paper, a hybrid prediction method (SA–SVM for short) is proposed by using simulated annealing (SA) and SVM to predict synthesis characteristics of the hydraulic valve, where SA is used to optimize the input parameters of SVM based prediction model. To validate the proposed prediction method, a specific hydraulic valve production is selected as a case study. The prediction results show that the proposed prediction method is applicable to forecast the synthesis characteristics of hydraulic valve and with higher accuracy. Comparing with Adaptive Neuro-Fuzzy Inference System (ANFIS) and Artificial Neural Networks (ANN) are also made.