Response time analysis of OPS5 production systems

The paper focuses on the problem of determining a priori the maximal response time of rule based programs. The response time analysis problem is an important problem, especially for real time systems. We study this problem in the context of OPS5 production systems. Two aspects of the response time of a program are investigated, the maximal number of rule firings and the maximal number of basic comparisons made by the Rete network during the execution of the program. The response time analysis problem is in general undecidable. However, a program terminates in a finite time if the rule triggering pattern of this program satisfies certain conditions. We present four such termination conditions for OPS5 production systems. An algorithm for computing an upper bound on the number of rule firings is then given. To have a better idea of the time required during execution, we present an algorithm that computes the maximal time required during the match phase in terms of the number of comparisons made by the Rete network. This measurement is sufficient since the match phase consumes about 90 percent of the execution time     

A refinement framework to support validation and maintenance of knowledge-based systems

In this article, we argue that a refinement tool capable of assisting the maintainer of a Knowledge-Based System (KBS) with updating and upgrading of its knowledge base can substantially expand the scope of his activities and prolong the life of the system. We show that refinement tasks involved in KBS maintenance are similar to those taking place at the development stage, and thus a uniform refinement framework can be designed to support both activities. After defining refinement tasks expected to take place at different stages of a KBS's life cycle, we present a refinement framework capable of supporting them. It utilizes a small number of domain-independent heuristics to search for possible rule revisions which are expected to eliminate errors detected during KBS validation. An extended example is given to illustrate how different refinement tasks are carried out.     

A graph-based approach for the co-registration refinement of very-high-resolution imagery and digital line graphic data

Co-registration refinement of very-high-resolution (VHR) imagery and digital-line-graphic (DLG) data is an important procedure before data fusion and analysis. However, existing approaches either make little consideration of topological relations between features or have to extract complete objects, which is very challenging. In this study, to overcome the drawbacks mentioned above, a graph-based approach is presented for the co-registering of VHR imagery and DLG data. Our proposed method uses a graph to represent the topological relations between buildings in both data sources, which helps match buildings in the two data sources and compute the affine transformation parameters. The proposed method is validated on three diverse VHR images, and two objective evaluation metrics (correctness and quality rate) are computed to evaluate its performance. It is shown that correctness and quality rate are averagely improved by 37.3% and 46.7%, respectively, after co-registration. These results indicate that our proposed method is effective in the co-registration of VHR imagery and DLG data.     

Self-stabilizing real-time OPS5 production systems

We examine the task of constructing bounded-time self-stabilizing rule-based systems that take their input from an external environment. Bounded response-time and self-stabilization are essential for rule-based programs that must be highly fault-tolerant and perform in a real-time environment. We present an approach for solving this problem using the OPS5 programming language as it is one of the most expressive and widely used rule-based programming languages. Bounded response-time of the program is ensured by constructing the state space graph so that the programmer can visualize the control flow of the program execution. Potential infinite firing sequences, if any, should be detected and the involved rules should be revised to ensure bounded termination. Both the input variables and internal variables are made fault-tolerant from corruption caused by transient faults via the introduction of new self-stabilizing rules in the program. Finally, the timing analysis of the self-stabilizing OPS5 program is shown in terms of the number of rule firings and the comparisons performed in the Rete network.     

A graph-based approach for population health analysis using Geo-tagged tweets

Multimedia Tools and Applications - We propose in this work a graph-based approach for automatic public health analysis using social media. In our approach, graphs are created to model the...     

A patterned approach for linking knowledge-based systems to external resources

Knowledge-based systems (KBSs) have been developed and used in industry and government as assistance systems, voting partner systems, and embedded applications. As web-based systems change the face of software implementations, these closed, internal KBSs need to be integrated into multicomponent applications that provide updated and extensible services. Therefore, KBSs must be adapted to an environment in which data and control are exchanged with external processes and resources; complementing other participating systems or using them to refine its own results. This integration can be a daunting task. If improperly done, it can result in an inefficient and unmanageable composite application. One approach to simplifying this task is the use of architectural patterns for integration. These patterns are assembled from functional entities that resolve component interoperability conflicts. In this paper, we describe an architectural pattern called the Knowledge Director pattern, which directs the integration of a closed KBS into a broader application environment.     

A knowledge-based approach to manage information systems interoperability

Interoperability is a key property of enterprise applications, which is hard to achieve due to the large number of interoperating components and semantic heterogeneity. The inherent complexity of interoperability problems implies that there exists no silver bullet to solve them. Rather, the knowledge about how to solve wicked interoperability problems is hidden in the application cases that expose those problems. The paper addresses the question of how to organise and use method knowledge to resolve interoperability problems. We propose the structure of a knowledge-based system that can deliver situation-specific solutions, called method chunks. Situational Method Engineering promotes modularisation and formalisation of method knowledge in the form of reusable method chunks, which can be combined to compose a situation-specific method. The method chunks are stored in a method chunk repository. In order to cater for management and retrieval, we introduce an Interoperability Classification Framework, which is used to classify and tag method chunks and to assess the project situation in which they are to be used. The classification framework incorporates technical as well as business and organisational aspects of interoperability. This is an important feature as interoperability problems typically are multifaceted spanning multiple aspects. We have applied the approach to analyse an industry case from the insurance sector to identify and classify a set of method chunks.     

A knowledge-based approach to the analysis of loops

The paper presents a knowledge-based analysis approach that generates first order predicate logic annotations of loops. A classification of loops according to their complexity levels is presented. Based on this taxonomy, variations on the basic analysis approach that best fit each of the different classes are described. In general, mechanical annotation of loops is performed by first decomposing them using data flow analysis. This decomposition encapsulates closely related statements in events, that can be analyzed individually. Specifications of the resulting loop events are then obtained by utilizing patterns, called plans, stored in a knowledge base. Finally, a consistent and rigorous functional abstraction of the whole loop is synthesized from the specifications of its individual events. To test the analysis techniques and to assess their effectiveness, a case study was performed on an existing program of reasonable size. Results concerning the analyzed loops and the plans designed for them are given     

A belief maintenance scheme for hierarchical knowledge-based image analysis systems

A variety of belief maintenance schemes for image analysis have been suggested and used to date. In the recent past, several researchers have suggested the use of the Dempster-Shafer theory of evidence for representation of belief. This approach appears to be particularly suited for knowledge-based image analysis systems because of its intuitively convincing ways of representing beliefs, support, plausibility, ignorance, dubiety, and a host of other measures that can be used for the purpose of decision making. It also provides a very attractive technique to combine these measures obtained from disparate knowledge sources. In this article, we show how the Dempster-Shafer theoretic concepts of refinement and coarsening can be used to aggregate and propagate evidence in a multi-resolution image analysis system based on a hierarchical knowledge base.     

Shortening matching time in OPS5 production systems

A rule-based system must satisfy stringent timing constraints when applied to a real-time environment. As the scale of rule-based expert systems increases, the efficiency of systems becomes a pressing concern. The most critical performance factor in the implementation of a production system is the condition-testing algorithm. We propose a new method based on the widely used RETE match algorithm. We show an approach designed to reduce the response time of rule-based expert systems by reducing the matching time. There are two steps in the method we propose: The first makes an index structure of the tokens to reduce the /spl alpha/-node-level join candidates. The second chooses the highest time tag for certain /spl beta/-nodes to reduce the amount of combinatorial match that is problematical in a real-time production system application. For this purpose, a simple compiler is implemented in C and the response time of test programs is measured.     

Specification and analysis of timing requirements for real-time systems in the CBD approach

In real-time software, not only computation errors but also timing errors can cause system failures, which eventually result in significant physical damages or threats to human life. To efficiently guarantee the timely execution of expected functions, it is necessary to clearly specify and formally verify timing requirements before performing detailed system design. With the expected benefit of reusability and extensibility, component technology has been gradually applied to developing industrial applications including real-time systems. However, most of component-based approaches applied to real-time systems lack in a systematic and rigorous approach to specifying and verifying timing requirements at an earlier development stage. This paper proposes a component-based approach to specifying and verifying timing requirements for real-time systems in a systematic and compositional manner. We first describe behaviors of the constituent components including timing requirements in UML diagrams, and then translate the UML diagrams into MTER nets, an extension of TER nets, to perform timing analysis in a compositional way. The merit of the proposed approach is that the specification and analysis results can be reused and independently maintained.     

A graph-based approach for discovering various types of associationrules

Mining association rules is an important task for knowledge discovery. We can analyze past transaction data to discover customer behaviors such that the quality of business decisions can be improved. Various types of association rules may exist in a large database of customer transactions. The strategy of mining association rules focuses on discovering large item sets, which are groups of items which appear together in a sufficient number of transactions. We propose a graph-based approach to generate various types of association rules from a large database of customer transactions. This approach scans the database once to construct an association graph and then traverses the graph to generate all large item sets. Empirical evaluations show that our algorithms outperform other algorithms which need to make multiple passes over the database     

A knowledge-based approach to design for manufacturability

In the light of growing global competition, organizations around the world today are constantly under pressure to produce high-quality products at an economical price. The integration of design and manufacturing activities into one common engineering effort has been recognized as a key strategy for survival and growth. Design for manufacturability (DFM) is an approach to design that fosters the simultaneous involvement of product design and process design. The implementation of the DFM approach requires the collaboration of both the design and manufacturing functions within an organization. Many reasons can be cited for the inability to implement the DFM approach effectively, including: lack of interdisciplinary expertise of designers; inflexibility in organizational structure, which hinders interaction between design and manufacturing functions; lack of manufacturing cost information at the design phase; and absence of integrated engineering effort intended to maximize functional and manufacturability objectives. The purpose of this research is to show how expert systems methodology could be used to provide manufacturability expertise during the design phase of a product. An object- and rule-based expert system has been developed that has the capability: (1) to make process selection decisions based on a set of design and production parameters to achieve cost-effective manufacture; and (2) to estimate manufacturing cost based on the identified processes. The expertise for primary process selection is developed for casting and forging processes. The specialized processes considered are die casting, investment casting, sand casting, precision forging, open die forging and conventional die forging. The processes considered for secondary process selection are end milling and drilling. The cost estimation expertise is developed for the die casting process, the milling and drilling operations, and the manual assembly operations. The results obtained from the application of the expert system suggest that the use of expert systems methodology is a feasible method for implementing the DFM approach.     

A graph-based QoS prediction approach for web service recommendation

Applied Intelligence - With the development of the Internet, the recommendation based on Quality of Service(QoS) is proven to be an efficient way to deal with the ever-increasing web services in...     

A knowledge-based approach for managing urban infrastructures

This paper presents a knowledge e-based approach dedicated to the efficient management, regulation, interactive and dynamic monitoring of urban infrastructures. This approach identifies the data and related treatments common to several municipal activities and defines the requirements and functionalities of the computer tools developed to improve the delivery and coordination of municipal services to the population. The resulting cooperative system called SIGIU is composed of a set of integrated operating systems (SYDEX) and the global planning and coordination system (SYGEC). The objective is to integrate the set of SYDEX and the SYGEC into a single coherent system for all the SIGIU's users according to their tasks, their roles, and their responsibilities within the municipal administration. SIGIU is provided by different measurement and monitoring instruments installed on some system's elements to be supervised. In this context, the information can be presented in different forms: video, pictures, data and alarms. One of SIGIU's objectives is the real-time management of urban infrastructures' control mechanisms. To carry out this process, the alarm control agent creates a mobile agent associated with the alarm, which is sent to a mobile station and warns an operator. Preliminary implementation results show that SIGIU supports effectively and efficiently the decision making process related to managing urban infrastructures.     

A knowledge-based approach to design

A framework is presented for constructing knowledge-based aids for design problems. In particular, we describe the organization of an interactive knowledge-based consultant for VLSI design (called VEXED?an acronym for VLSI expert editor), and a prototype implementation of VEXED. The paper focuses on the principles underlying the design of VEXED, and on several lessons and research issues that have arisen from implementing and experimenting with this prototype.     

Formalizing an engineering approach to cooperating knowledge-based systems

A theoretical grounding is provided for a cooperating knowledge-based systems (CKBS) model which is based upon agents, cooperation blocks, and cooperation block hierarchies. Our model describes the requirements for task decomposition, negotiation, cooperation and coordination, fault tolerance, and recoverability, these requirements in turn defining a holonic system. The behavioral properties of our model are described using state transition diagrams and properties of correctness and termination are proven.