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On the steady-state queue size distribution of the discrete-time Geo/G/1 queue with repeated customers

QUEUEING SYSTEMS 1995年第1-2期21卷 199-215页

作者： Yang, T Li, H MT ST VINCENT UNIV DEPT MATHHALIFAXNS B3M 2J6CANADA

In this paper, we study the steady-state queue size distribution of the discrete-time Geo/G/1 retrial queue. We derive analytic formulas for the probability generating function of the number of customers in the system in steady-state. It is shown that the stochastic decomposition law holds for the Geo/G/1 retrial queue. recursive formulas for the steady-state probabilities are developed. computations based on these recursive formulas are numerically stable because the recursions involve only nonnegative terms. Since the regular Geo/G/1 queue is a special case of the Geo/G/1 retrial queue, the recursive formulas can also be used to compute the steady-state queue size distribution of the regular Geo/G/1 queue. Furthermore, it is shown that a continuous-time M/G/1 retrial queue can be approximated by a discrete-time Geo/G/1 retrial queue by dividing the time into small intervals of equal length and the approximation approaches the exact when the length of the interval tends to zero. This relationship allows us to apply the recursive formulas derived in this paper to compute the approximate steady-state queue size distribution of the continuous-time M/G/1 retrial queue and the regular M/G/1 queue.

关键词： discrete-time queues generating functions recursive computation retrial queues stochastic decomposition

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Numerical error analysis in Zernike moments computation

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IMAGE AND VISION COMPUTING 2006年第9期24卷 960-969页

作者： Papakostas, G. A. Boutalis, Y. S. Papaodysseus, C. N. Fragoulis, D. K. Democritus Univ Thrace Dept Elect & Comp Engn GR-67100 Xanthi Greece Natl Tech Univ Athens Sch Elect & Comp Engn GR-15773 Athens Greece

An exact analysis of the numerical errors being generated during the computation of the Zemike moments, by using the well-known 'q-recursive' method, is attempted in this paper. Overflow is one kind of error, which may occur when one needs to calculate the Zemike moments up to a high order. Moreover, by applying a novel methodology it is shown that there are specific formulas, which generate and propagate 'finite precision error'. This finite precision error is accumulated during execution of the algorithm, and it finally 'destroys' the algorithm, in the sense that eventually makes its results totally unreliable. The knowledge of the exact computation errors and the way that they are generated and propagated is a fundamental step for developing more robust error-free recursive algorithms, for the computation of Zemike moments. (c) 2006 Elsevier B.V. All rights reserved.

关键词： Zernike moments recursive computation finite precision error numerical stability image vision feature extraction

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EXPONENTIAL INTEGRALS

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COMMUNICATIONS OF THE ACM 1973年第12期16卷 761-763页

作者： GAUTSCHI, W PURDUE UNIV DEPT COMP SCILAFAYETTEIN 47907

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ESTIMATION OF POWER SYSTEM FREQUENCY USING A TIME-DOMAIN METHOD

ESTIMATION OF POWER SYSTEM FREQUENCY USING A TIME-DOMAIN MET...

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International Conference on Advanced Computing and Communication Systems (ICACCS)

作者： Sangeetha, U. Sundararajan, D. Adhiyamaan Coll Engn Dept EEE Hosur 635109 Tamil Nadu India

ISBN: (纸本)9781479935062

Power system frequency is an important parameter in power quality monitoring. Due to nonlinear loads and other problems, the frequency slowly varies around its nominal value of 50Hz. To estimate the instantaneous frequency value, therefore, a dynamic signal model is required. In earlier works, Taylor series is used to model the waveform. The coefficients of the Taylor series are computed using the Discrete Fourier Transform. The method requires the computation of overlapping segments of the waveform samples. However, the direct use of the Fast Fourier Transform is redundant and requires a higher computation complexity. In this paper, the use of an algorithm to compute the successive discrete Fourier transforms is proposed that substantially reduces the computational complexity of the algorithm. Further, the proposed problem formulation results in a better convergence. Detailed simulation results are presented that confirm the validity of the approach.

关键词： Frequency estimation Taylor series discrete Fourier transform recursive computation

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DUAL recursive NETWORK FOR FAST IMAGE DERAINING 26

DUAL RECURSIVE NETWORK FOR FAST IMAGE DERAINING

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26th IEEE International Conference on Image Processing (ICIP)

作者： Cai, Linwen Li, Si-Yao Ren, Dongwei Wang, Ping Tianjin Univ Sch Math Tianjin Peoples R China Tianjin Univ Coll Intelligence & Comp Tianjin Peoples R China SenseTime Res Beijing Peoples R China

ISBN: (纸本)9781538662496

Recent years have witnessed the great progress on deep image deraining networks. On the one hand, deraining performance has been significantly improved by designing complex network architectures, yielding high computational cost. On the other hand, several lightweight networks try to improve computational efficiency, but at the cost of notable degrading deraining performance. In this paper, we propose a dual recursive network (DRN) for fast image deraining as well as comparable or superior deraining performance compared with state-of-the-art approaches. Specifically, our DRN utilizes a residual network (ResNet) with only 2 residual blocks (Res-Block), which is recursively unfolded to remove rain streaks in multiple stages. Meanwhile, the 2 ResBlocks can be recursively computed in one stage, forming the dual recursive network. Experimental results show that DRN is very computationally efficient and can achieve favorable deraining results on both synthetic and real rainy images.

关键词： Image deraining deep learning recursive computation

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A Branch and Bound Algorithm for Feature Subset Selection

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IEEE Transactions on Computers 1977年第9期C-26卷 917-922页

作者： Narendra, Patrenahalli M. Fukunaga, Keinosuke Honeywell Systems and Research Center Minneapolis MN 55413 United States School of Electrical Engineering Purdue University Lafayette IN 47907 United States

A feature subset selection algorithm based on branch and bound techniques is developed to select the best subset of m features from an n-feature set. Existing procedures for feature subset selection, such as sequential selection and dynamic programming, do not guarantee optimality of the selected feature subset. Exhaustive search, on the other hand, is generally computationally unfeasible. The present algorithm is very efficient and it selects the best subset without exhaustive search. computational aspects of the algorithm are discussed. Results of several experiments demonstrate the very substantial computational savings realized. For example, the best 12-feature set from a 24-feature set was selected with the computational effort of evaluating only 6000 subsets. Exhaustive search would require the evaluation of 2 704 156 subsets. Copyright © 1977 by The Institute of Electrical and Electronics Engineers, Inc.

关键词： Branch and bound combinatorial optimization feature selection recursive computation

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Interaction trees: Representing recursive and impure programs in Coq

Interaction trees: Representing recursive and impure program...

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Proceedings of the ACM on Programming Languages

作者： Xia, Li-Yao Zakowski, Yannick He, Paul Hur, Chung-Kil Malecha, Gregory Pierce, Benjamin C. Zdancewic, Steve University of Pennsylvania PhiladelphiaPA United States Seoul National University Seoul Korea Republic of BedRock Systems BostonMA United States

Interaction trees (ITrees) are a general-purpose data structure for representing the behaviors of recursive programs that interact with their environments. A coinductive variant of "free monads," ITrees are built out of uninterpreted events and their continuations. They support compositional construction of interpreters from event handlers, which give meaning to events by defining their semantics as monadic actions. ITrees are expressive enough to represent impure and potentially nonterminating, mutually recursive computations, while admitting a rich equational theory of equivalence up to weak bisimulation. In contrast to other approaches such as relationally specified operational semantics, ITrees are executable via code extraction, making them suitable for debugging, testing, and implementing software artifacts that are amenable to formal verification. We have implemented ITrees and their associated theory as a Coq library, mechanizing classic domain- and category-theoretic results about program semantics, iteration, monadic structures, and equational reasoning. Although the internals of the library rely heavily on coinductive proofs, the interface hides these details so that clients can use and reason about ITrees without explicit use of Coq's coinduction tactics. To showcase the utility of our theory, we prove the termination-sensitive correctness of a compiler from a simple imperative source language to an assembly-like target whose meanings are given in an ITree-based denotational semantics. Unlike previous results using operational techniques, our bisimulation proof follows straightforwardly by structural induction and elementary rewriting via an equational theory of combinators for control-flow graphs. © 2020 Copyright held by the owner/author(s).

关键词： Program debugging Flow graphs Forestry Iterative methods Program compilers Semantics Software testing Theorem proving Trees (mathematics) Verification Coinduction Compiler correctness Denotational semantics Equational reasoning Monads Operational semantics Operational techniques recursive computation

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Image Deraining for UAV Using Split Attention Based recursive Network

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Transactions of Nanjing University of Aeronautics and Astronautics 2020年第4期37卷 539-549页

作者： FENG Yidan DENG Sen WEI Mingqiang College of Computer Science and Technology/College of Artificial Intelligence Nanjing University of Aeronautics and AstronauticsNanjing 211106P.R.China

Images captured in rainy days suffer from noticeable degradation of scene *** aerial vehicles(UAVs),as important outdoor image acquisition systems,demand a proper rain removal algorithm to improve visual perception quality of captured images as well as the performance of many subsequent computer vision *** deal with rain streaks of different sizes and directions,this paper proposes to employ convolutional kernels of different sizes in a multi-path *** attention is leveraged to enable communication across multiscale paths at feature level,which allows adaptive receptive field to tackle complex *** incorporate the multi-path convolution and the split attention operation into the basic residual block without increasing the channels of feature ***,every block in our network is unfolded four times to compress the network volume without sacrificing the deraining *** performance on various benchmark datasets demonstrates that our method outperforms state-of-the-art deraining algorithms in both numerical and qualitative comparisons.

关键词： unmanned aerial vehicle(UAV) deep neural network image deraining recursive computation split attention

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Discrete-time risk models with surplus-dependent premium corrections

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APPLIED MATHEMATICS AND computation 2023年 437卷

作者： Osatakul, Dhiti Li, Shuanming Wu, Xueyuan Chulalongkorn Univ Chulalongkorn Business Sch Dept Stat Bangkok Thailand Univ Melbourne Fac Business & Econ Dept Econ Melbourne Vic 3010 Australia

This paper studies discrete-time risk models with insurance premiums adjusted according to claims experience. The premium correction mechanism follows the well-known princi-ple in the non-life insurance industry, the so-called bonus-malus system. The bonus-malus framework that we study here extends the current literature by allowing the premium correction rules to vary according to the current surplus level of the insurance company. The main goal of this paper is to evaluate the risk of ruin for the insurer who implements the proposed bonus-malus system. Two premiums correction principles are examined: by aggregate claims or by claim frequency. Further, the Parisian type of ruin is also consid-ered, where the premium adjustment rules are different in positive-and negative-surplus environment.(c) 2022 Elsevier Inc. All rights reserved.

关键词： Discrete-time risk model Bonus-malus system Finite-time ruin recursive computation Surplus-dependent premiums Parisian ruin

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Discrete-Time Risk Model With Time-Varying Premiums: Analysis of Ruin Probabilities

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APPLIED STOCHASTIC MODELS IN BUSINESS AND INDUSTRY 2024年第0期

作者： Osatakul, Dhiti Li, Shuanming Wu, Xueyuan Chulalongkorn Univ Dept Stat Chulalongkorn Business Sch Bangkok Thailand Univ Melbourne Dept Econ Melbourne Vic Australia

Our paper explores a discrete-time risk model with time-varying premiums, investigating two types of correlated claims: main claims and by-claims. Settlement of the by-claims can be delayed for up to two time periods, representing real-world insurance practices. We examine a premium principle based on reported claims, using recursively computable finite-time ruin probabilities to evaluate the performance of time-varying premiums. Our findings suggest that, under specific assumptions, a higher probability of by-claim settlement delays leads to lower ruin probabilities. Moreover, a stronger correlation between main claims and their associated by-claims results in higher ruin probabilities.

关键词： bonus-malus delayed claim discrete-time risk model finite-time ruin recursive computation

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