16560725
rCOS: A refinement calculus of object systems
This article presents a mathematical characterization of object-oriented concepts by defining an observation-oriented semantics for a relational object-based language with a rich variety of features including subtypes, visibility, inheritance, type casting, dynamic binding and polymorphism. The language can be used to specify object-oriented designs as well as programs. We present a calculus that supports both structural and behavioural refinement of object-oriented designs. The design calculus is based on the predicate logic in Hoare and He's Unifying Theories of Programming (UTP).
13004956
Consistency checking of UML requirements
This paper discusses how to check consistency of UML requirements model which consists of a use case model and a conceptual class model with system constraints. Based on a given semantics, the requirements consistency can be defined and checked formally. The consistency among use cases and constraints are classified into five types. A system operation of interaction between actor and system is formally defined as a pair of pre and post conditions. An atomic use case is described as one system operation, and a composed use case may be defined as several system operations described by an activity diagram. Thus, each use case can also be modelled as a pair of pre and post conditions by composing the pre and post conditions of system operations by introducing a sequence composition operation. Requirement consistency can be logically checked based on the semantics. A simple library system is used as a case study to illustrate the feasibility of the method.
1176633
Consistent code generation from UML models
Relational calculus of object systems (rCOS) is an OO-language which is equipped with an observation-oriented semantics and a refinement calculus based on the Hoare and He's unifying theories of programming (UTP). In this paper, we give syntactic definitions for class diagrams and sequence diagrams in UML 2.0. Based on these definitions, we give an algorithm for checking the consistency of a class diagram and a sequence diagram. Furthermore, we develop an algorithm to generate rCOS code from any given consistent class diagram and sequence diagram.
216012840
Specification and verification of fault-tolerance, timing, and scheduling
Fault-tolerance and timing have often been considered to be implementation issues of a program, quite distinct from the functional safety and liveness properties. Recent work has shown how these no...
14189544
Verification, refinement and scheduling of real-time programs
Abstract A real-time program can be developed by refining a specification into program code. Verification of the timing properties of the program is then usually done at two levels: verification of the ordering of timed actions in the program and proof that execution of the program on a specific system will meet its timing requirements. Refinement is done within a formal model but the second step requires a different framework in which scheduling theory analysis is used and actual program execution times can be taken into account. The implementation of a program on a system is said to be feasible or schedulable if it will meet all the timing deadlines. This paper shows how the feasibility of scheduling a real-time program can also be proved as a step in the refinement of the program from its specification. Verification of this step of refinement makes use of methods from scheduling theory within a formal system development framework.
2945218
On querying geospatial and georeferenced metadata resources in G-Portal
G-Portal is a Web portal system providing a range of digital library services to access geospatial and georeferenced resources on the Web. Among them are the storage and query subsystems that provide a central repository of metadata resources organized under different projects. In G-Portal, all metadata resources are represented in XML (Extensible Markup Language) and they are compliant to some resource schemas defined by their creators. The resource schemas are extended versions of a basic resource schema making it easy to accommodate all kinds of metadata resources while maintaining the portability of resource data. To support queries over the geospatial and georeferenced metadata resources, a XQuery-like query language known as RQL (Resource Query Language) has been designed. We present the RQL language features and provide some experimental findings about the storage design and query evaluation strategies for RQL, queries.
16103436
Web-Based Parallel Simulation of AGVs Using Java and JINI
The vision of Computational Grids promises an exciting future for the distributed simulation community. In this project we make a small but practical step toward the grand vision of distributed simulation by using certain prevailing Internet technologies to enable access of simulation services anytime and anywhere. Specifically, this project focuses on accessing distributed simulation of AGVs (Automated Guided Vehicle) in container port operations through the World Wide Web. The objectives are to explore and address relevant issues, evaluate various approaches, demonstrate a workable version. We initially construct the AGV simulation system in an indirect communication model and identify its merits and demerits. Then, we explore the use of JINI technology for an efficient and robust direct communication architecture.
6908345
A swarm intelligence routing algorithm for MANETs
This paper presents a novel swarm intelligence inspired routing algorithm (EARA) for mobile ad hoc networks. Based on the understanding of the evolutionary cooperation in the biological swarm, which provides an alternative solution resilient against changes in the dynamic environment, We use the principle of swarm intelligence for the reinforcement of optimal routes with only local communication (here, local communication is defined as neighbourto-neighbour one only). The data traffic is influenced at each node, and the communicating nodes observe this influence to update their tables. We also include an evaluation, and the simulation results show that this routing algorithm scales well to a variety of network conditions.
1313086
Image-based surface detail transfer
Changing an object's appearance by adding geometric details is desirable in many real-world applications. Bump mapping has acted as an alternative to adding geometrical details, to an otherwise smooth object. But constructing visually interesting bump maps requires practice and artistic skills. Computer vision techniques have helped for modeling real-world objects and their surface details. In our approach, for cases where we only want to transfer geometrical details from one object to another, we might not need to explicitly compute 3D structures. In particular, our novel technique captures the geometrical details of an object from a single image in a way that is independent of the object's reflectance property. We can then transfer geometrical details to another surface, producing the appearance of a new surface with added geometrical details while preserving the object's reflectance property. Our method's advantages are that it's simple to implement, requires only a single image for each object, and produces effective results.
2119274
Dynamical mobile terminal location registration in wireless PCS networks
In this paper, we propose a mobile terminal (MT) location registration/update model. In this model, the registration decision is based on two factors-the time elapsed since last call arrival and the distance the MT has traveled since last registration. It is established that the optimal registration strategy can be represented by a curve. Only when the state of the system reaches this curve is a registration performed. In order for an MT to calculate its traveled distance, an interactive implementation scheme and a distance calculation algorithm are developed. When the call interarrival times are independent and geometrically distributed, the proposed model becomes a distance-based model and, in this case, the optimal registration strategy is of threshold structure. For the distance-based model, a single sample path-based ordinal optimization algorithm is devised. In this algorithm, without any knowledge about the system parameters, the MT observes the system state transitions, estimates the ordinal of a set of strategies, and updates the registration strategy adaptively. Since only a single sample path is used, this algorithm can be implemented online. Several numerical examples are provided to compare the proposed model and the existing ones.