6516220
Resource-Constrained Workflow Modeling
Business processes are often constrained by resource availability. This is particularly true in an emergency response system where large quantity of resources, including emergency responders, ambulances, fire trucks, medications, food, clothing, etc., are required. In our previous work, we introduced WIFA model to meet the needs of incident command systems workflow modeling and analysis. In this paper, we extend WIFA to take resources into account when modeling and enacting workflows. A formal resource-constrained workflow model is defined and the state transitions rules are established to support workflow analysis. An example is given to illustrate the use of the model.
28830107
Introducing software architecture specification and analysis in SAM through an example
Abstract Software architecture study has become one of the most active research areas in software engineering in the recent years. Although there have been many published results on specification and analysis method of software architectures, information on sound systematic methodology for modeling and analyzing software architectures is lacking. In this article, we present a formal systematic software architecture specification and analysis methodology called SAM and show how to apply SAM to specify a command control (C2) system and to analyze its real-time constraints.
15454128
An Approach for Modeling and Analysis of Security System Architectures
Security system architecture governs the composition of components in security systems and interactions between them. It plays a central role in the design of software security systems that ensure secure access to distributed resources in networked environment. In particular, the composition of the systems must consistently assure security policies that it is supposed to enforce. However, there is currently no rigorous and systematic way to predict and assure such critical properties in security system design. A systematic approach is introduced to address the problem. We present a methodology for modeling security system architecture and for verifying whether required security constraints are assured by the composition of the components. We introduce the concept of security constraint patterns, which formally specify the generic form of security policies that all implementations of the system architecture must enforce. The analysis of the architecture is driven by the propagation of the global security constraints onto the components in an incremental process. We show that our methodology is both flexible and scalable. It is argued that such a methodology not only ensures the integrity of critical early design decisions, but also provides a framework to guide correct implementations of the design. We demonstrate the methodology through a case study in which we model and analyze the architecture of the Resource Access Decision (RAD) Facility, an OMG standard for application-level authorization service.
15835310
An Intuitive Formal Approach to Dynamic Workflow Modeling and Analysis
The increasing dynamics and the continuous changes of business processes raise a challenge to the research and implementation of workflows. The significance of applying formal approaches to the modeling and analysis of workflows has been well recognized and many such approaches have been proposed. However, these approaches require users to master considerable knowledge of the particular formalisms, which impacts the application of these approaches on a larger scale. This paper presents a new formal, yet intuitive approach for the modeling and analysis of workflows, which attempts to overcome the above problem. In addition to the abilities of supporting workflow validation and enactment, this new approach possesses the distinguishing feature of allowing users who are not proficient in formal methods to build up and dynamically modify the workflow models that address their business needs.
35219345
Integrated architectural modeling and analysis for high-assurance command and control system design
A real-time architectural specification (RAS) approach and its application to command and control (C2) systems are presented. The objective is to establish a formal foundation that will enable us to integrate existing rich but fragmented formal techniques for system specification and verification into practical and scaleable formal engineering methods to support the design and development of highly reliable real-time distributed systems. The contribution of RAS is twofold; first, it provides a formal system that integrates the system's timing requirements and the propagation of the requirements into the process of architectural modeling and design and provides a systematic way to enforce that the requirements are met in every step of the design process. Second, it offers an incremental and more scalable approach for design modeling. These two features together make RAS a suitable model for the design of C2 systems. Based on these features, we further present an incremental method for verifying timing properties of a RAS model that helps to reduce the complexity of analysis both at a given design level or across different design levels.
8350188
Constraint Propagation And Progressive Verification For Component-Based Process Model
System assembly is one of the major issues in engineering complex component-based systems. This is especially true when heterogeneous, COTS and GOTS distributed systems, typical in industrial applications, are involved. The goal of system assembly is not only to make constituent components work together, but also to ensure that the components as a whole behave consistently and guarantee certain end-to-end properties. Despite recent advances, there is a lack of understanding about software composability, as well as theory and techniques for checking and verifying component-based systems. A theory of software system constraints about components, their environment and about system as a whole is the necessary foundation toward solid understanding of the composability of component-based systems. In this paper, we present a systematic approach for constraint specification and constraint propagation in concert with design refinement with a novel technique to ensure consistency between system-wide and component constraints in a design composition process of component-based systems. The consistent constraint propagation is used in our approach to drive progressive verification of the design. It allows us to verify overall design composition without interference of internal details of component designs. Verification is done separately at architectural and component levels without having to compose results of component analyses. A component can be safely replaced with alternative design without re-verifying the overall system composition so long as the replacement conforms to the corresponding interface and component constraint(s).
6919037
A systems engineering approach for constructing certifiable real-time distributed systems
In this paper, we present a systems engineering methodology for constructing certifiable realtime distributed systems. In the proposed approach, an architectural and algorithmic solution to an application problem is designed by considering the "weakest" models including the weakest asynchronous computational model and multimodal arrival model. Furthermore, timeliness properties are described using Jensen's benefit accrual predicates. Once a system solution is designed, timeliness properties are established by constructing necessary feasibility conditions that are expressed as non-valued predicates. The predicates are quantified and verified to produce the specification of a certified solution. We illustrate the approach by considering a packet transmission problem that desire soft timeliness. We present a certifiable solution to this problem that consists of switched Ethernet, a soft real-time packet scheduling algorithm (that was previously developed), and feasibility conditions.
411372
Stratification Approach to Modeling Video
The explosive growth of audiovisual information in the last few years has made the development of advanced video modeling and management tools an urgent task. In this research, we investigate the use of stratification approach to model the contextual information of video contents as multi-layered strata. By judiciously choosing the right level and types of strata, we are able to automate a major part of the strata extraction process. Using the strata as the basis, we have developed advanced functionalities to support the flexible retrieval and content-based browsing of video. A prototype has been developed to support the whole process of video management, from strata extraction, to indexing, retrieval and browsing. The prototype is tested in the domain of news video and the system has been found to be effective.
7624272
PhyloMiner: A Tool for Evolutionary Data Analysis
Currently, phylogenetic tree techniques are being used in multiple areas, from tree of life problems to pathogen recognition to drug discovery. With all of these applications for phylogenetic tree techniques, methods are needed to exploit the knowledge modeled in phylogenetic trees more thoroughly. One such information point of interest is the behavior of frequent patterns in phylogenetic trees. While there are many techniques that look at maximal, consensus and super tree patterns, there are few techniques that look at frequent, but not maximal pattern. This demonstration paper presents PhyloMiner, a tool that automatically discovers frequent agreement subtrees from multiple phytogenies. It introduces this topic of frequent agreement subtrees and then concludes with describing the PhyloMiner tool that implements these concepts and is available freely on the World Wide Web
206541019
An online self-organizing neuro-fuzzy control for autonomous underwater vehicles
Controlling autonomous underwater vehicles (AUVs) in an uncertain and unstructured environment presents many challenging control problems. Model-based control strategies have been used with limited success. The paper presents an online self-organizing neuro-fuzzy control that serves as a better alternative control scheme in controlling AUVs. The proposed self-organizing neuro-fuzzy controller is a six-layer feedforward neural network that is capable of self-constructing and self-restructuring its internal node connectivity and learning the parameters of each node based on incoming training data. Computer simulations have been conducted to validate the performance of the proposed neuro-fuzzy controller and an experimental verification has been scheduled to verify if on ODIN, an autonomous underwater vehicle developed at the University of Hawaii.
1715921
Medium access control in mobile ad hoc networks: challenges and solutions
Summary Mobile ad hoc networks (MANETs) are useful in environment where fixed network infrastructure is unavailable. To function normally, MANETs demand an efficient and distributed medium access control (MAC) protocol. However, characteristics of MANETs such as radio link vulnerability, mobility, limited power pose great challenges on MAC design. This paper surveys the recent advances in MAC design for MANETs. We first identify the challenges that are facing MAC in MANETs. Then we discuss the proposed MAC schemes according to their design goals, focusing on some critical design issues, and tradeoffs. Finally, we point out some future research directions. Copyright # 2006 John Wiley & Sons, Ltd.