207130315
Formal Designs for Embedded and Hybrid Systems
The design of embedded and hybrid systems requires powerful mechanisms for modeling data, state, concurrency and real-time behaviour. The {first} part of this paper illustrates a powerful design notation Timed Communicating Object Z (TCOZ) that has both channel based and sensor/actuator based interfaces. We believe that TCOZ is well suited for presenting more complete and coherent design models for complex embedded and hybrid systems. However, the challenge is how to analyze and check these models with tools support. One effective approach is to project (transform) the design models into multiple domains, then to use existing specialized tools in those domains to perform the checking and analyzing tasks. The second part of this paper demonstrates one particular projection from TCOZ designs to Timed Automata (TA) models so that TA model checkers can be used to check time related properties.
5239234
The role of secondary attributes in formal object modelling
When modelling a large and complex system, clarity of the specification becomes an important factor. In object-oriented specification, the states of individual objects are captured by the values of their attributes. Frequently however, there are dependencies between the attributes of an object. An appropriate indication of which attributes are primary (independent) and which are secondary (dependent) can add significantly to clarity. This paper details the notion of secondary attributes, their roles and implications in formal object-oriented specification.
10062286
Integrating Object-Z with timed automata
When designing a complex system, Object-Z is a powerful logic-based language for modeling the system state aspects, and timed automata is an excellent graph-based notation for capturing timed control behaviour of the system. This paper presents an effective combination of the two techniques with novel composition and communication mechanisms. The combined notation enhances Object-Z with realtime modeling capability and also extends timed automata with enhanced structure and state modeling features.
18649413
Capturing periodic concurrent interactions of mission computer tasks
Safety critical systems, such as aviation systems controlled by software, often have hard real-time requirements. Producing the correct result at the right time is the fundamental goal of such systems. Formally specifying the system functions and the timing requirements is the crucial step towards achieving such a goal. Aviation systems often need to be modified or upgraded on a regular basis, i.e. functionality and timing constraints may be altered. Therefore, the formal specification of such systems needs to be easily reused, maintained and modified. This paper demonstrates how the task scheduling aspects of an aircraft mission computer can be formalised in TCOZ.
15362726
State, event, time and diagram in system modeling
The design of complex systems requires powerful mechanisms for modeling state, concurrent events, and real-time behavior; as well as for visualising and structuring systems in order to control complexity. Methods integration has become a recent research trend in software specification and design. In the graphical area, many object-oriented methods have merged into one, the Unified Modeling Language (UML) which combines various diagrammatic modeling techniques to model static and dynamic aspects of software systems. Although traditional formal methods have not scale-up well, new integrated formal methods show great promise. This tutorial will present the state of the art in formal modeling techniques (state-based Object-Z and event-based Timed CSP), their integration (TCOZ), and transformation techniques from the integrated formalism to UML diagrams. An XML web environment for projecting integrated formal models to UML diagrams will also be demonstrated.
18404140
Deep Semantic Links of TCSP and Object-Z: TCOZ Approach
Abstract. Formal methods can be used in effective combination only if the semantic links between individual methods are clearly established. This paper discusses the semantic design of TCOZ, a language blended from Object-Z and TCSP. The semantic model adopted is the infinite timed failures model of TCSP, extended to include initial state and update events for modelling operations on internal state. An infinite trace model has been used so as to ensure proper account is taken of the potentially unbounded non-determinism allowed by Z schemas.
15990035
Content-based retransmission for 3-D wavelet video streaming on the Internet
Improving the QoS of video streaming with packet loss is a challenging topic of research. In this paper, we propose a novel content-based retransmission scheme to address this issue. The basic idea is to jointly consider the packets' contents and the channel conditions to optimize QoS. The goal is to deliver the best quality of video possible under the same channel condition. Using the proposed retransmission scheme, we have designed a 3D wavelet video streaming system. Simulation results show that the content-based retransmission can improve the video quality by more than 2 dB compared with the existing non-content-based delay-constrained retransmission when the channel loss rate is high.
14829052
A formal framework for design component contracts
Building large software systems out of existing software components can save time and cost. These software components range from architectural and design components in different phases of software development. Component technologies lead to increasing productivity and flexibility. However, it also introduces significant problems in ensuring the integrity and reliability of these composed systems because of their complex software topologies, interactions, and transactions. In this paper, we concentrate on the pattern-based design components and their compositions, which are captured as contracts through a composition theory. More specifically, design component contract is defined based on process calculus and logic programming; the properties that related to the design component contract are captured, and tools are used to automatically verify these properties. This research will enhance the capabilities of formal system modeling and analysis by providing a rigorous basis for high-assurance integration of diverse pattern-based components.
2048896
The Use of Parallel Processing to Achieve Decentralized Control of a Segmented Reflector Telescope
14676361
Service Oriented Evolutions and Analyses of Design Patterns
The globalization of software development helps to reduce business cost by outsourcing software design and development tasks. However, it also poses new challenges on the collaboration and management of the development teams at multiple remote sites. Service-oriented approaches facilitate Web-based collaborations and reuses. In this paper, we propose a service-oriented architecture for the collaboration of software design teams in distributed locations. In particular, our approach allows different design teams from multiple remote sites to design software systems with design patterns, to evolve the designs, and to check the consistencies of the design evolutions. We provide service-oriented prototype tools for the design teams from different physical locations to model the software system designs in UML, to evolve the designs based on XSLT transformations, and to check the consistencies based on the Java theorem prover. A case study is presented to illustrate our approach
6734225
Supply chain networks, electronic commerce, and supply side and demand side risk
In this paper, we develop a supply chain network model in which both physical and electronic transactions are allowed and in which supply side risk as well as demand side risk are included in the formulation. The model consists of three tiers of decision-makers: the manufacturers, the distributors, and the retailers, with the demands associated with the retail outlets being random. We model the optimizing behavior of the various decision-makers, with the manufacturers and the distributors being multicriteria decision-makers and concerned with both profit maximization and risk minimization. We derive the equilibrium conditions and establish the finite-dimensional variational inequality formulation. We provide qualitative properties of the equilibrium pattern in terms of existence and uniqueness results and also establish conditions under which the proposed computational procedure is guaranteed to converge. We illustrate the supply chain network model through several numerical examples for which the equilibrium prices and product shipments are computed. This is the first multitiered supply chain network equilibrium model with electronic commerce and with supply side and demand side risk for which modeling, qualitative analysis, and computational results have been obtained.