Explicit modeling of semantics associated with composite states in UML statecharts

UML statecharts are used for describing dynamic aspects of system behavior. The work presented here extends a general Petri net-based methodology to support formal modeling of UML statecharts. The approach focuses on the specific task of generating explicit transition models associated with the hierarchical structure of statechart. We introduce a state-transition notation to serve as an intermediate model for conversion of UML statecharts, and in particular, the complexity of composite states, to other target specifications. By defining a process for deriving, from UML statecharts, a state-transition notation that can serve as an intermediate state machine model, we seek to deepen understanding of modeling practices and help bridge the gap between model development and model analysis. This work covers all of the primary issues associated with the hierarchical structure of composite states, including entry and exit transitions, transition priorities, history states, and event dispatching. Thus, the results provide an important step forward toward the goal of modeling increasingly complex semantics of UML statecharts. This material is based upon work supported by the U.S. Army Research Office under grant number DAAD19-01-1-1-0672, and the U.S. National Science Foundation under grant number CCR-9988168.     

Extending statecharts with temporal logic

The task of designing large real-time reactive systems, which interact continuously with their environment and exhibit concurrency properties, is a challenging one. The authors explore the utility of a combination of behavior and function specification languages in specifying such systems and verifying their properties. An existing specification language, statecharts, is used to specify the behavior of real-time reactive systems, while a new logic-based language called FNLOG (based on first-order predicate calculus and temporal logic) is designed to express the system functions over real time. Two types of system properties, intrinsic and structural, are proposed. It is shown that both types of system properties are expressible in FNLOG and may be verified by logical deduction, and also hold for the corresponding behavior specification     

Executable visual software modeling—the ZOOM approach

In this paper, we introduce a new executable visual software modeling approach called ZOOM (Z-Based Object Oriented Modeling). ZOOM extends a subset of UML-2 notations by providing UI modeling notations and a formal integration mechanism. ZOOM allows software modeling using both graphical and textual views for its structural, behavioral and UI models. Through a pre-defined event model, ZOOM integrates these models, and provides the runtime execution semantics for both code generation and software animation.     

Knowledge object modeling

Knowledge objects are an integration of the object-oriented paradigm with logic rules. The proper integration provides a flexible and powerful environment, as rule-based components provide facilities for deductive retrieval and pattern matching, and object-oriented components provide a clear intuitive structure for programs in the form of class hierarchies. Based on the knowledge object concept, this paper presents a factor-centered representation language, Factor++, which models logic rules into the object-oriented paradigm, and a scheduling system, Schedular, using the Factor++ framework The construction of Schedular demonstrates that by using an object-oriented representation of knowledge objects, users can be given explicit control of the object hierarchy to customize the system to their particular needs, which includes letting users select among scheduling and other methods. In Schedular, rules are designed as derivation rules and constraint rules. The purpose of rules is either to restrict object structure and behavior, or to infer new data from the existing data. Rules are arranged in positions so that object methods are automatically firing up if environment changes are detected by these rules     

Hybrid MARTE statecharts

The specification of modeling and analysis of real-time and embedded systems (MARTE) is an extension of the unified modeling language (UML) in the domain of real-time and embedded systems. Even though MARTE time model offers a support to describe both discrete and dense clocks, the biggest effort has been put so far on the specification and analysis of discrete MARTE models. To address hybrid real-time and embedded systems, we propose to extend statecharts using both MARTE and the theory of hybrid automata. We call this extension hybrid MARTE statecharts. It provides an improvement over the hybrid automata in that: the logical time variables and the chronometric time variables are unified. The formal syntax and semantics of hybrid MARTE statecharts are given based on labeled transition systems and live transition systems. As a case study, we model the behavior of a train control system with hybrid MARTE statecharts to demonstrate the benefit.     

Extending statecharts with process algebra operators

This paper describes an adaptation of statecharts to take advantage of process algebra operators like those found in CSP and EB³. The resulting notation is called algebraic state transition diagrams (ASTDs). The process algebra operators considered include sequence, iteration, parallel composition, and quantified synchronization. Quantification is one of the salient features of ASTDs, because it provides a powerful mechanism to precisely and explicitly define cardinalities in a dynamic model. The formal semantics of ASTDs is expressed using the operational style typically used in process algebras. The target application domain is the specification and implementation of information systems.     

Executable specifications with data-flow diagrams

Specifications of information systems applications are often based on the use of entity-relationship (ER) and data-flow diagrams (DFD), which cover, respectively, the conceptual modelling of data and funtions. This paper introduces VLP: an executable visual language for formal specifications and prototyping which integrates ER and DFD diagrams in a semantically rigorous and clear way. Unlike existing commercial products (so-called CASE tools), which can support good-quality documentation, simple forms of consistency checking and bookkeeping, VLP also supports executable specifications, which provide a prototype of the desired application. After reviewing the principles of VLP, the paper outlines the structure of the ECASET environment in which VLP is embedded. In particular, it shows how the environment supports the stepwise derivation of specifications, from informal to formal, and how it supports specification-in-the-large.     

Automatic layout of statecharts

Graphical notations are widely used for system specification. The usefulness of these notations depends primarily on their readability. Hence, automatic methods are needed to obtain efficient and understandable graphical representations of requirements. In this paper, we present an algorithm that automatically generates layouts of statecharts. We assume that relevant information is stored in a structure that we call a decomposition tree, and we draw the graph that models a statechart in a hierarchical fashion. Our approach excludes diagrams with inter‐level transitions. Copyright © 2001 John Wiley & Sons, Ltd.     

Multiresolution free form object modeling with point sampled geometry

In this paper an efficient framework for the creation of 3D digital content with point sampled geometry is proposed. A new hierarchy of shape representations with three levels is adopted in this framework. Based on this new hierarchical shape representation, the proposed framework offers concise integration of various volumetric- and surface-based modeling techniques, such as Boolean operation, offset, blending, free-form deformation, parameterization and texture mapping, and thus simplifies the complete modeling process. Previously to achieve the same goal, several separated algorithms had to be used independently with inconsistent volumetric and surface representations of the free-form object. Both graphics and industrial applications are presented to demonstrate the effectiveness and efficiency of the proposed framework.     

A knowledge-based object modeling advisor for developing quality object models

Object models or class diagrams are widely used for capturing information system requirements in terms of classes with attributes and operations, and relationships among those classes. Although numerous guidelines are available for object modeling as part of requirements modeling, developing quality object models has always been considered a challenging task, especially for novice systems analysts in business environments. This paper presents an approach that can be used to support the development of quality object models. The approach is implemented as a knowledge-based system extension to an open source CASE tool to offer recommendations for improving the quality of object models. The knowledge component of this system incorporates an ontology of quality problems that is based on a conceptual model quality framework commonly found in object models, the findings of related empirical studies, and a set of analysis patterns. The results obtained from an empirical evaluation of the prototype demonstrate the utility of this system, especially with respect to recommendations related to the model completeness aspect of semantic quality.     

Heterogeneous object modeling: A review

A review on the recent development in heterogeneous object modeling is provided in this paper. General problems and prevalent solutions to the modeling of heterogeneous objects are investigated. Vigorous heterogeneous object representations are roughly classified into three major categories: evaluated models, unevaluated models and composite models. We reveal their similarities and study their strengths and weaknesses in terms of the representational capacities, intuitiveness, exactness, compactness, efficiency and other criteria. Different design paradigms are briefly reviewed to provide an overview of the state-of-the-art in heterogeneous object design. Finally, open problems and possible future directions are discussed.     

带纹理映射的牙膏体构造法及其OpenGL实现

在探讨三维Morphing(形状过渡)技术的基础上,提出了一种带不失真纹理映射的牙膏体构造法,较详尽地阐述了三角网格剖分算法的思想.牙膏体是一个包含帽体和膏体两部分的复杂曲面体,从顶部圆台过渡到中间圆面、最后过渡到底部一条直线,它们在拓扑结构上是同构的,因此能通过OpenGL的顶点数组编程加以实现.这种组合曲面造型法不仅方便,还提供丰富的参数选择,具有一定的应用意义,也能有效应用于二维半形状、火箭体和鱼类等绘制.     

基于FPGA的高斯建模运动目标检测算法

运动目标检测技术是在图像序列中将运动目标从背景图像中提取出来,为高级运动分析提供必要的信息,因此运动目标的快速正确检测对后期处理至关重要。为了满足高速场合的要求,减少目标检测的消耗时间,采用Altera公司的CycloneII系列的FPGA,研究设计了基于FPGA的高斯建模运动目标检测算法。该算法采用了流水线方法设计算法结构,以及浮点化整的方法处理浮点计算,实验结果表明,该设计在FPGA上运行快速稳定,检测效果良好,并且精度高。     

Multimedia object modeling and storage allocation strategies

The improvements in disk speeds have not kept up with improvements in processor and memory speeds. Many techniques have been proposed and utilized to maximize the bandwidths of storage devices. These techniques have proven useful for conventional data, but when applied to multimedia data, they tend to be insufficient or inefficient due to the diversified data types, bandwidth requirements, file sizes and structures of complex objects of multimedia data. In this paper, we discuss the design of an efficient multimedia object allocation strategy that strives to achieve the expected retrieval rates and I/O computational requirements of objects; and also effectively balances the loads on the storage devices. We define a multimedia object model, describe the multimedia object and storage device characteristics, the classification of the multimedia objects according to their I/O requirements, and the fragmentation strategies. We use a bipartite graph model for mapping of fragments to storage devices. A cost function based on a disk utilization per allocated space, the amount of free space, and the bandwidth of a storage device is used to determine the optimal allocation for an object's data.     

Application graphics modeling support through object orientation

The Graphical Application Modeling Support system (Grams), a three-dimensional graphics system that raises the abstraction level at which the application programmer and the end user interact with the system in the image-generation process, is described. The application, graphics and rendering layers of Grams and its organization of class hierarchies are discussed. An application of the Grams system is presented     

Research issues in modeling complex object shapes

The methods for high-level abstraction of complex objects described can support mechanisms that process abstracted information directly. Accordingly, the visual computer architecture, multimedia database systems, and multimedia operating systems are attractive areas for future research. The methods discussed are: the singular points approach; decomposition using Morse theory; modeling by the manifolds; Reeb graph of topological structure, visual reconstruction of objects; and approaches to abstraction     

A hierarchical representation for heterogeneous object modeling

A hierarchical representation for heterogeneous object modeling is presented in this paper. To model a heterogeneous object, Boundary representation is used for geometry representation, and a novel Heterogeneous Feature Tree (HFT) structure is proposed to represent the material distributions. HFT structure hierarchically organizes the material variation dependency relationships and is intuitive in modeling different types of material gradations. Based on the HFT structure, a recursive material evaluation algorithm is proposed to dynamically evaluate the material compositions at a specific location. Such a hierarchical representation guarantees complex material gradations and the user's design intent can be intuitively represented. Example heterogeneous objects modeled with this scheme are provided and potential applications are discussed.     

An integral approach to free-form object modeling

Presents an approach to free-form object modeling from multiple range images. In most conventional approaches, successive views are registered sequentially. In contrast to the sequential approaches, we propose an integral approach which reconstructs statistically optimal object models by simultaneously aggregating all data from multiple views into a weighted least-squares (WLS) formulation. The integral approach has two components. First, a global resampling algorithm constructs partial representations of the object from individual views, so that correspondence can be established among different views. Second, a weighted least-squares algorithm integrates resampled partial representations of multiple views, using the techniques of principal component analysis with missing data (PCAMD). Experiments show that our approach is robust against noise and mismatch