Question-asking strategies for Horn clause systems

An expert system applies the deduction rules in its knowledge base to a set of initial data to reach a conclusion. When the initial data are insufficient, the expert system may ask the user for additional information. This paper analyzes effectiveness and efficiency of question-asking strategies in expert systems with Horn clause knowledge bases. An effective strategy reaches a conclusion after asking as few questions as possible. An efficient strategy can be computed quickly. We prove that effective strategies are, unfortunately, not efficient. However, we present a somewhat less effective but very efficient strategy. It employs an algorithm which simultaneously performs deduction and question selection in log-linear time.Supported in part by NSF grant DMS-8513970.     

A cost effective fault-tolerant scheme for RAIDs

The rapid progress in mass storage technology has made it possible for designers to implement large data storage systems for a variety of applications.One of the efficient ways to build large storage systems is to use RAIDs only when one error occurs .But in large RAIDs systems ,the fault probability will increase when the number of disks increases ,and the use of disks with big storage capacity will cause the recovering time to prolong,thus the probability of the second disk‘‘‘‘‘‘‘‘s fault will incerease Therefore,it is necessary to develop methods to recover data when two or more errors have occurred In this paper,a fault tolerant scheme is proposed based on extended Reed-Solomon code,a recovery procedure is designed to correct up to two errors which is implemented by software and hardware together,and the scheme is verified by computer simulation,In this scheme,only two redundant disks are used to recover up to two disks‘‘‘‘‘‘‘‘ fault .The encoding and decoding methods,and the implementation based on software and hardware are described.The application of the scheme in software RAIDs that are builit in cluster computers are also described .Compared with the existing methods such as EVENODD and DH ,the proposed scheme has distinct improvement in implementation and redundancy.     

Inference flexibility in Horn clause knowledge bases and the simplex method

This paper shows that the basis matrix inverse of the linear program associated with a propositional Horn clause knowledge base provides a proof structure of inference by forward chaining. The basis matrix inverse indicates how each assertion determines the others and is itself determined by the others. This tabulated proof structure provides a convenient way of making inference transparent and flexible.     

Optimal cost effective design of hybrid hardware redundant systems

In many critical applications of digital systems, fault tolerance has been an essential architectural attribute for achieving high reliability. We address the problem of designing an optimal hybrid hardware redundant system. The designer of a system is always confronted with the problem of trading off reliability against cost. On the one hand, it is essential to provide for each vital module of the system as many spare units as possible in order to ensure high reliability. On the other hand, it is essential not to have an excessively costly, heavy or bulky system. In this paper we determine the optimal number of spare units which minimizes the expected total system cost. A numerical example is provided to illustrate the methods.     

An Inplementation of Pure Horn Clause Logic Programming in a Reduction System

Many reduction systems have been presented for implementing functional programming languages.We propose here an extension of a reduction architecture to realize a kind of logic programming-pure Horn clause logic programming.This is an attempt to approach amalgamation of the two important programming paradigms.     

A distortion cost modification strategy for adaptive pentary steganography

In this paper, a pentary steganography scheme is proposed employing the multi-layered STCs, which takes the embedding interactions into consideration. First, based on the definition of local correlation for the four-neighborhood, we link the modification direction of the central pixel with that of its four-neighborhood. Secondly, a modification degree strategy (MDS) is proposed to adjust the costs of the pixels dynamically. And the cost of pixels is assigned utilizing the MDS, which divides the process of distortion calculation into two steps of initializing and updating distortion cost. Finally, the scheme is obtained incorporating the MDS with the existing adaptive scheme S-UNIWARD of pentary version. Experimental results show that the proposed scheme is capable of providing large capacity, and has a better performance than adaptive steganography scheme S-UNIWARD of pentary version in resisting the SRM and maxSRMd2 detection when the payload is larger than 0.5 bpp. Also, the strategy could be combined with other adaptive steganography schemes of pentary version. Besides, the proposed scheme outperforms some ternary adaptive schemes with both feature sets SRM and maxSRMd2 when the payload is from 0.05bpp to 0.5bpp.     

A data mining-constraint satisfaction optimization problem for cost effective classification

We propose a data mining-constraint satisfaction optimization problem (DM–CSOP) where it is desired to maximize the number of correct classifications at a lowest possible information acquisition cost. We show that the problem can be formulated as a set of several binary variable knapsack optimization problems, which are solved sequentially. We propose a heuristic hybrid simulated annealing and gradient-descent artificial neural network (ANN) procedure to solve the DM-CSOP. Using a real-world heart disease data set, we show that the proposed hybrid procedure provides a low-cost and high-quality solution when compared to a traditional ANN classification approach.     

A practical control strategy for servo-pneumatic actuator systems

A practical control strategy with a simple controller structure is proposed for servo-pneumatic cylinder actuator systems. Theoretical analysis reveals that the acceleration of the piston indirectly represents the cylinder chamber pressure difference so it is possible to employ acceleration feedback instead of pressure feedback in the construction of servo-pneumatic actuator control systems. The main features of the control strategy developed in the paper are (1) using acceleration feedback to improve the stability of the system; and (2) introducing time-delay minimisation and optimised null offset compensation to address the problem of time delay and dead zone, which are mainly caused by the compressibility of air and friction. The experimental studies have been conducted using an asymmetric pneumatic cylinder system and the results show that the system performance has been much improved when compared with a conventional PID controller.     

A client-assisted interval caching strategy for video-on-demand systems

In a Video-on-Demand (VoD) system, in order to guarantee smooth playback of a video stream, sufficient resources (such as disk I/O (Input/Output) bandwidth, network bandwidth) have to be reserved in advance. Thus, given limited resources, the number of simultaneous streams can be supported by a video server is restricted. Due to the mechanical nature, the I/O subsystem is generally the performance bottleneck of a VoD system, and there have been a number of caching algorithms to overcome the disk bandwidth limitation. In this paper, we propose a novel caching strategy, referred to as client-assisted interval caching (CIC) scheme, to balance the requirements of I/O bandwidth and cache capacity in a cost-effective way. The CIC scheme tends to use the cache memory available in clients to serve the first few blocks of streams so as to dramatically reduce the demand on the I/O bandwidth of the server. Our objective is to maximize the number of requests that can be supported by the system and minimize the overall system cost. Simulations are carried out to study the performance of our proposed strategy under various conditions. The experimental results show the superior of CIC scheme to the tradition Interval Caching (IC) scheme, with respect to request accepted ratio and average servicing cost per stream.     

A cost effective on-site fault diagnosis method for home appliance rotor failures

Microsystem Technologies - Rotating components are one of the most important machine parts used in many industrial applications. Rotating machine commonly used in homes has a washing machine, which...     

A simulation framework for technical systems life cycle cost analysis

This paper deals with the construction of a simulation framework for technical systems life cycle cost (LCC) analysis. It also deals with the concept of software reuse in event-based simulation, since the framework involves simulation of all cost generating activities related to a technical system, from its planning and acquisition phases until its final discard. The basic principles of object-oriented programming and simulation software efficiency, reuse, extensibility and evolvability are analyzed and the concepts of computational reflection and frameworks are explored. Finally, the framework is described in detail and its extension points, based on the inheritance mechanism, are shown.     

A multi-regulator sliding mode control strategy for output-constrained systems

This paper proposes a multi-regulator control scheme for single-input systems, where the setpoint of a regulated output must be changed under the constraint that a set of minimum-phase outputs remain within prescribed bounds. The strategy is based on a max–min selector system frequently used in the aerospace field. The regulators used for the regulated and limited outputs are of the sliding mode type, where the sliding variable is defined as the difference between an output and its allowable limit. The paper establishes overall asymptotic stability, as well as invariance properties leading to limit protection. The design methodology is illustrated with a detailed simulation example on thrust control of a turbofan engine.     

A run-time load balancing strategy for highly parallel systems

We discuss a simple run-time load balancing strategy which applies to numerical applications working on planar domains with localized data dependency. We develop an iterative and adaptive partitioner, able to work in a distributed way among the processors of a parallel system. Our algorithm subdivides data space into general quadrilaterals, where each processor works on the data of one area. The topology of these domains is that of a rectangular grid and does not change during execution. In this way a very simple and efficient communication structure is given. The administration overhead due to irregular geometry is small. Also, the overhead caused by periodically read-justing load balance is rather small because of the adaptivity and parallelity of the partitioning algorithm. We ran an scientific application to compare our method with a method working by recursive bisection, and obtained satisfactory results.     

A new fragment re-allocation strategy for NoSQL database systems

NoSQL databases are famed for the characteristics of high scalability, high availability, and high fault-tolerance. So NoSQL databases are used in a lot of applications. The data partitioning strategy and fragment allocation strategy directly affect NoSQL database systems’ performance. The data partition strategy of large, global databases is performed by horizontally, vertically partitioning or combination of both. In the general way the system scatters the related fragments as possible to improve operations’ parallel degree. But the operations are usually not very complicated in some applications, and an operation may access to more than one fragment. At the same time, those fragments which have to be accessed by an operation may interact with each other. The general allocation strategies will increase system’s communication cost during operations execution over sites. In order to improve those applications’ performance and enable NoSQL database systems to work efficiently, these applications’ fragments have to be allocated in a reasonable way that can reduce the communication cost i.e., to minimize the total volume of data transmitted during operations execution over sites. A strategy of clustering fragments based on hypergraph is proposed, which can cluster fragments which were accessed together in most operations to the same cluster. Themethod uses a weighted hypergraph to represent the fragments’ access pattern of operations. A hypergraph partitioning algorithmis used to cluster fragments in our strategy. This method can reduce the amount of sites that an operation has to span. So it can reduce the communication cost over sites. Experimental results confirm that the proposed technique will effectively contribute in solving fragments re-allocation problem in a specific application environment of NoSQL database system.     

A sharing-oriented design strategy for networked knowledge organization systems

Designers of networked knowledge organization systems often follow a service-oriented design strategy, assuming an organizational model where one party outsources clearly delineated business processes to another party. But the logic of outsourcing is a poor fit for some knowledge organization practices. When knowledge organization is understood as a process of exchange among peers, a sharing-oriented design strategy makes more sense. As an example of a sharing-oriented strategy for designing networked knowledge organization systems, we describe the design of the PeriodO period gazetteer. We analyze the PeriodO data model, its representation using JavaScript Object Notation-Linked Data, and the management of changes to the PeriodO dataset. We conclude by discussing why a sharing-oriented design strategy is appropriate for organizing scholarly knowledge.     

REFiLL: A lightweight programmable middleware platform for cost effective RFID application development

Middleware platforms for RFID data filtering and collection tend to be resource intensive, costly and/or provide a low degree of programmability. In this paper, we introduce REFiLL, a lightweight middleware framework that can significantly ease the development of RFID systems. The introduced framework fits within the overall EPC global network architecture as a programmable filtering solution, sitting between the EPC (Electronic Product Code) reader virtualization layer and EPC application level events. Thanks to a set of well defined programming constructs, REFiLL renders application development a task of authoring a set of XML-based files, which are also editable within a visual development environment. Following the presentation of the REFiLL framework, we also describe the process of application development, along with sample prototype applications.