Managing disruption in an imperfect production–inventory system

In this paper, a disruption recovery model is developed for an imperfect single-stage production–inventory system. For it, the system may unexpectedly face either a single disruption or a mix of multiple dependent and/or independent disruptions. The system is usually run according to a user defined production–inventory policy. We have formulated a mathematical model for rescheduling the production plan, after the occurrence of a single disruption, which maximizes the total profit during the recovery time window. The model thereby generates a revised plan after the occurrence of the disruption. The mathematical model, developed for a single disruption, is solved by using both a pattern search and a genetic algorithm, and the results are compared using a good number of randomly generated disruption test problems. We also consider multiple disruptions, that occur one after another as a series, for which a new occurrence may or may not affect the revised plan of earlier occurrences. We have developed a new dynamic solution approach that is capable of dealing with multiple disruptions on a real-time basis. Some numerical examples and a set of sensitivity analysis are presented to explain the usefulness and benefits of the developed model. The proposed quantitative approach helps decision makers to make prompt and accurate decisions for managing disruption.     

A net-structure learning system for pattern description

This paper discusses a computer program that recognizes and describes two-dimensional patterns composed of subpatterns. The program also recognizes all patterns in a scene consisting of several patterns.

Patterns are stored in a learned hierarchical, net-structure memory. Weighted links between memory nodes represent subpattern/pattern relationships. Both short term and permanent memories are used.

Pattern recognition is accomplished with a serial heuristic search algorithm, which attempts to search memory and compute input properties efficiently. Without special processing, the program can be asked to look for all occurrences of a specified pattern in a scene.     

蚁群算法及其实现方法研究

蚁群算法是一种相对较新的启发式方法,通过模拟蚂蚁的觅食行为解决问题,是目前昆虫算法中较成功的例子.蚁群算法的本质是一种并行的、自组织的算法,它可应用于更好地组织大数目实体的相互作用过程,如货郎担问题、车辆绕径问题、排程问题等。该文简述了蚁群算法的起源和发展,总结了蚁群算法的特点和不足及针对这些不足提出的各种改进方法,并介绍了和蚁群算法相关的几种具体应用。最后,文章探讨了蚁群算法研究中仍存在的问题和以后的发展方向。     

一个线性的启发式图搜索算法

本文描述了一个能够改善启发函数的启发式图搜索算法．它利用搜索过程中的信息,改动启发函数h,保持搜索树上始终满足单调限制条件,使算法的最坏复杂度从B′的O（N²）（L.Méró,1984）降为O（N）．本文还证明了新算法的可采纳性、线性的复杂度,并同算法B′作了性能比较．     

Charged system search for optimal design of frame structures

The charged system search (CSS) algorithm is utilized for design of frame structures. The algorithm is inspired by the laws in physics. The CSS utilizes a number of charged particles which influence each other based on their fitness values and their separation distances considering the governing law of Coulomb. A comparison between the characteristics of the CSS algorithm and other well-known meta-heuristics is performed to indicate their similarities and differences. Some benchmark frame examples are optimized with the CSS algorithm. Comparison of the results of CSS with some other meta-heuristic algorithms shows the robustness of the new algorithm.     

多因素问题的启发式搜索算法MFRA

本文新定义了一类多因素启妇式搜索问题，提出了适于此类问题求解的启发式搜索算法ＭＦＲＡ。文中研究了算法ＭＦＲＡ的可采纳性质，单调限制性质和比较性质等。基于算法ＩＤＡ的思想，提出了ＭＦＲＡ的改进算法ＭＦＲＡ－ＩＤＡ，这一算法具有线性存储空间这一重要特性。     

Finding the rib cage in chest radiographs

We describe a system of computer algorithms that finds the rib cage in chest radiographs. Our algorithms link the dorsal and ventral portions of the rib contours such that each rib is identified and can be displayed individually. In a preliminary application of our system to five adult chest radiographs, about 90% of the ribs were found, and ca. 15% of the computed rib contours were false.     

宽度优先反复加宽及其启发式搜索算法研究

首先针对搜索树中深度固定且目标唯一的寻优问题,指出宽度优先反复加宽的搜索效率要比深度优先反复加深的搜索效率高,基于此,提出了基于宽度优先反复加宽的启发式搜索算法ＩＷＡ＊,算法ＩＷＡ＊是可采纳的。为了保持算法ＩＷＡ＊的搜索效率高于算法ＩＤＡ＊的搜索效率,同时又使算法ＩＷＡ＊的存贮空间复杂度减低,文中基于分层技术,提出了基于深度优先的ＩＷＡ＊算法──ＩＤＷＡ＊。算法ＩＤＷＡ＊也是一个可采纳的启发式搜索算法。     

领域相关的Web网站抓取方法

本文提出了一种抓取领域相关的Web站点的方法,可以在较小的代价下准确地收集用户所关心领域内的网站。这种方法主要改进了传统的聚焦爬虫（Focused Crawler）技术,首先利用Meta-Search技术来改进传统Crawler的通过链接分析来抓取网页的方法,而后利用启发式搜索大大降低了搜索代价,通过引入一种评价领域相关性的打分方法,迭到了较好的准确率。本文详细地描述了上述算法并通过详细的实验验证了算法的效率和效果。     

融合AdaBoost和启发式特征搜索的人脸性别分类

提出一种基于AdaBoost的人脸性别分类方法,从一张低分辨率灰度人脸图像中辨认出一个人的性别。将启发式搜索算法融于AdaBoost算法框架中,从而发现新的可用于更好分类的特征。利用该方法进行人脸性别分类方面的实验,当使用少于500个像素比较时,正确识别率达到了93%以上,这与迄今已公布的最佳的分类器支持向量机（SVM）的正确识别率相当,但速度却快得多。     

蚂蚁算法在民航飞机排班问题中的应用

蚂蚁算法是一种比较新的组合优化算法,在很多问题的求解中取得了成效。该文将蚂蚁算法引入了民航飞机排班问题的求解过程,并举例说明了蚂蚁算法在飞机排班问题中的可行性,为民航飞机排班问题的解决提出了新的思路。     

噪声图象中提取边界的随机启发式搜索方法

在噪声图象中如何有效地提取边界是图象分析领域中的难点。启发式搜索的方法常常用于提取边界,但是,这种方法由于采用固定的起始点、固定的引导度量以及对图象仅进行一次性搜索,对噪声往往很敏感,为此提出了一种随机启发式搜索算法,该方法随机地选取起始点,并依照引导度量的概率反复地进行随机搜索获得各种可能的边界轨迹,然后进行各搜索轨迹的积累自增强,最后根据自增强积累统计结果获得边界。大量的实验结果证明,在噪声图象中,随机启发式搜索方法可以在提取出有意义边界的同时有效地抑制噪声。     

Workpiece recognition and inspection by a model-based scene analysis system

A scene analysis system for the recognition and inspection of overlapping workpieces in visually noisy scenes is described. It consists of a preprocessing algorithm based on an edge-following operator and a model-based analysis algorithm. In the preprocessing stage, which is not described in detail, features such as corners, straight lines, circles and circular arcs are extracted and described by a few parameters. In the analysis stage, the pattern features extracted by the preprocessing algorithm are used to synthesize, in model-guided fashion, a prototype of the workpiece, which is continuously checked against the model. A similarity measure indicates the match between model and scene. Besides topographical features, the analysis makes use of grey levels, textural measures and values representing colors.Results obtained with different, partly occluded workpieces are given.     

Rescheduling rail networks with maintenance disruptions using Problem Space Search

The creation of train timetables for long-haul single track networks is a challenging process. This task is more difficult if track maintenance disruptions are to be taken into account. This paper describes how the Problem Space Search (PSS) meta-heuristic can be used for large scale problems to create quality timetables in which both train movements and scheduled track maintenance are simultaneously considered. We show that the PSS meta-heuristic can rapidly generate a large number of alternative train timetables and then describe how the technique is generalized to construct an integrated timetable which includes track maintenance. We show how the technique can also be used as an operational tool where a revised schedule can be quickly generated to take into account the new state of a disrupted system. A case study for a single track rail network in Queensland Australia, which spans a distance of 480 km, has 57 crossing loops and typically carries over 50 trains per day is discussed.     

Flight operations recovery: New approaches considering passenger recovery

The sources of disruption to airline schedules are many, including crew absences, mechanical failures, and bad weather. When these unexpected events occur, airlines recover by replanning their operations. In this paper, we present airline schedule recovery models and algorithms that simultaneously develop recovery plans for aircraft, crews, and passengers by determining which flight leg departures to postpone and which to cancel. The objective is to minimize jointly airline operating costs and estimated passenger delay and disruption costs. This objective works to balance these costs, potentially increasing customer retention and loyalty, and improving airline profitability. Using an Airline Operations Control simulator that we have developed, we simulate several days of operations, using passenger and flight information from a major US airline. We demonstrate that our decision models can be applied in a real-time decision-making environment, and that decisions from our models can potentially reduce passenger arrival delays noticeably, without increasing operating costs.     

Filtered-beam-search-based algorithm for dynamic rescheduling in FMS

In the practical production process of a flexible manufacturing system (FMS), unexpected disturbances such as rush orders arrival and machine breakdown may inevitably render the existing schedule infeasible. This makes dynamic rescheduling necessary to respond to the disturbances and to improve the efficiency of the disturbed FMS. Compared with the static scheduling, the dynamic rescheduling relies on more effective and robust search approaches for its critical requirement of real-time optimal response. In this paper, a filtered-beam-search (FBS) -based heuristic algorithm is proposed to solve the dynamic rescheduling problem in a large and complicated job shop FMS environment with realistic disturbances. To enhance its performance, the proposed algorithm makes improvement in the local/global evaluation functions and the generation procedure of branches. With respect to a due date-based objective (weighted quadratic tardiness), computational experiments are studied to evaluate the performance of the proposed algorithm in comparison with those of other popular methods. The results show that the proposed FBS-based algorithm performs very well for dynamic rescheduling in terms of computational efficiency and solution quality.     

Incremental Beam search

Beam search is a heuristic search algorithm that explores a state-space graph by expanding w most promising nodes at each level (depth) of the graph, where w is called the beam-width which is taken as input from the user. The quality of the solution produced by beam search does not always monotonically improve with the increase in beam-width making it difficult to choose an appropriate beam-width for effective use. We present an algorithm called Incremental Beam Search (IncB) which guarantees monotonicity, and is also anytime in nature. Experimental results on the sliding-tile puzzle, the traveling salesman, and the single-machine scheduling problems show that IncB significantly outperforms basic monotonic methods such as iterative widening beam search as well as some of the state-of-the-art anytime heuristic search algorithms in terms of the quality of the solution produced at the end as well as the anytime performance.