38096630
Quality-related measures of unreliable machines with preventive maintenance
In this paper, we study a production system in which some of the products made are defective. The distribution of such defective products is assumed to depend on the total number of products made since the last maintenance. Quality-related measures of interest are the average out-going quality (AOQ) and the variance of the out-going quality (VOQ) which we define as the mean and the variance of the long-run fraction of non-defective products respectively. The system is periodically maintained. Two maintenance policies are considered: one is to perform maintenance after a fixed number of products have been made; and the other is to perform maintenance when the machine becomes idle or a fixed number of products have been made. The system is modelled as an M/G/1 queue with vacations. The queue length of orders for products, the AOQ and VOQ are analysed for these two policies. Numerical examples are provided to compare the efficiency of the two models.
12790595
Optimally scheduling N customer arrival times for a single-server system
Abstract In this paper, we investigate the problem of scheduling a finite number of customer arrivals for a single-server system. Under the assumptions that the customers arrive at the system by scheduled appointments and they request random amount of times for service, the question is: what are the ‘best’ arrival times so that the total operating cost is minimized? This type of queueing problem has important applications in production systems as well as in service systems. Using phase-type distribution functions and matrix algebraic manipulation, we are able to obtain recursive expressions for the customer flow-time distributions, from which the mean and variance, or higher moments, can be easily computed. A computational procedure is developed that efficiently evaluates the mean flow-times for large number of customers that need to be scheduled. This procedure is integrated with a nonlinear program that determines the optimal customer arrival times.
2060430
A Defect in Dempster-Shafer Theory
By analyzing the relationships among chance, weight of evidence and degree of belief, we show that the assertion "probability functions are special cases of belief functions" and the assertion "Dempster's rule can be used to combine belief functions based on distinct bodies of evidence" together lead to an inconsistency in Dempster-Shafer theory. To solve this problem, we must reject some fundamental postulates of the theory. We introduce a new approach for uncertainty management that shares many intuitive ideas with D-S theory, while avoiding this problem.
13042163
Non-Axiomatic Reasoning System (Version 4.1)
NARS (Non-Axiomatic Reasoning System) is an intelligent reasoning system. It answers questions according to the knowledge originally provided by its user. What makes it different from conventional reasoning systems is its ability to learn from its experience and to work with insufficient knowledge and resources. The NARS 4.1 demo is a Java applet. It comes with help information and simple examples to show how the system does deduction, induction, abduction, analogy, belief revision, membership evaluation, relational inference, backward inference, new concept formation, and so on, in a unified manner. The demo also allows its user to create new examples to test the system, as well as to see the internal structure and process when the system is running. The on-line help document contains links to relevant publications. A previous version of the system, NARS 3.0, is described in detail in (Wang, 1995), which, and other related publications, are available at the author’s web page.
39858986
On the Connectivity of (4;g)-Cages
45269182
Maximally flat allpass fractional Hilbert transformers
Recently, a generalization of the Hilbert transformer, the fractional Hilbert transformer, was defined and developed. In this paper, we propose a design of the allpass filter to realize the fractional Hilbert transformer based on the maximally flat approximation to the desired phase response. The coefficients are solved analytically for the traditional Hilbert transformer which is a special case of the fractional Hilbert transformer. Based on the closed-form coefficients, we show that the maximally flat allpass Hilbert transformers are stable. Design examples indicate that the proposed filters exhibit good approximation to the desired frequency response.
2857808
A knowledge-based segmentation algorithm for enhanced recognition of handwritten courtesy amounts
Abstract A knowledge-based segmentation algorithm to enhance recognition of courtesy amounts on bank checks is proposed in this paper. This algorithm uses multiple contextual cues to enhance segmentation and recognition. The system described extracts context from the handwritten numerals and uses a syntax parser based on a deterministic finite automaton to provide adequate feedback to enhance recognition. Further feedback is provided by a simple legal amount decoder that determines word count and recognizes several key words (e.g. thousand and hundred). This provides an additional semantic constraint on the dollar section. The segmentation analysis module presented is capable of handling a number of commonly used styles for courtesy amount representation. Both handwritten and machine written courtesy and legal amounts were utilized to test the efficacy of the preprocessor for the check recognition system described in this paper. The substitution error was reduced by 30–40% depending on the input check mix.