Integration of batching and scheduling for hot rolling production in the steel industry

This paper investigates the hot rolling production scheduling problem in the steel industry and proposes a new mixed integer programming model for this problem based on the monolithic modeling strategy that integrates batching and scheduling. Using this strategy, the new model can simultaneously schedule multiple turns and simultaneously determine the production timetable of these turns in a global optimal view. A long-term tabu search heuristic using frequency-based memory is developed to obtain near-optimal solutions for this problem. Three kinds of speed-up strategies are developed to accelerate the search procedure of the proposed tabu search. A practical scheduling system combining the proposed mathematical model and the tabu search heuristic has been developed and tested on instances collected from practical production data. The experimental results show that the proposed mathematical model and the tabu search heuristic outperform both the current manual scheduling method and the traditional serial method.     

GC–MS characterization of oligomers in polyadipates used as plasticizers for PVC in food contact

Fourteen commercial polyadipates and a polysebacate were analysed for their components of a molecular mass below 1000 Da, primarily with the aim of generating the background data for measuring the migration of this type of polymeric additives from plasticized PVC (e.g. cling films and gaskets of lids) into foods or food simulants. Since the composition of the material <1000 Da varies between the polyadipates, the main components must be identified to enable a correct quantification. Polyadipates differ in the diol used as linker, their termination (acid or alcohol) and in the end‐capping (free alcohols, acetylation, acylation with fatty acids, esterification with octanol/decanol). Gas chromatography (GC) provides good separation, but the material remaining in the column up to high temperatures decomposes and forms a hump in the rear part of the chromatogram. Examples of mass spectra are shown, the most indicative fragments pointed out and spectra of 159 components listed. The polyadipates and the sebacate are characterized by their structure, the main components <1000 Da and the fraction of material <1000 Da. Copyright © 2006 John Wiley & Sons, Ltd.     

空气钻井条件下录井工艺方法与技术配套探讨

针对玉门青西油田深部高陡易斜地层存在可钻性差、自然造斜能力强，致使钻井周期长、成本高等特点，中油集团公司在吐哈油田设立钻探“工程探索井（L14井）”重大科研项目，试验研究空气钻井技术。根据L14井录井的实际情况，首先分析了空气钻井条件对录井带来的影响和常规的录井工艺方法和技术设备存在的不足；从5个方面介绍了录井工艺、技术方法的改进，探讨了空气钻井下的岩屑上返理论；介绍了配置装备的改进，分析了该井录井配套技术的应用效果。从该试验井的录井效果看，经改进的录井工艺、方法及装备基本上能满足空气钻井的需要，取全取准了地质及工程资料，为地质解释和评价提供了可靠依据；在工程监测、保障施工安全方面，工程录井也发挥了作用。但综合录井仪软件及后台评价程序还不适应空气钻井的需要，相关的理论研究及工艺完善还有许多课题尚需深入。     

微电热新技术及其在食品加工领域中的应用前景

ＤＺＲ是新型微电热材料的简称，其发明人是孔德凯先生，该材料已先后获美国、澳大利亚、英国、法国、意大利、瑞典、日本等国专利。发明人的杰出贡献在于不仅找到了ＤＺＲ材料的制造方法，而且实现了元件和部件的系列化和标准化，并提出了微球理论，创立了孔氏面电阻定律、面热材料功率计算定律、寿命计算定律，引起了各国的极大关注。本文阐述了国内外电热材料研究概况及国际发明专利ＤＺＲ技术特点及其在食品加工领域中应用前景。     

Taste recognition threshold concentrations of styrene in oil-in-water emulsions and yoghurts

Taste recognition threshold concentrations (TRTC) of styrene were determined in samples of oil-in-water emulsions (30–300 g kg^?1 oil) and yoghurts (1–30 g kg^?1 fat), spiked with styrene. The observed TRTC increased linearly with increasing fat content and ranged from 0–3 to 2–1 mg kg^?1 for the emulsions and from 36 to 171 g kg^?1 for the yoghurts. Styrene equilibrium partition coefficients between emulsions and their respective vapour phases were determined. The concentrations of styrene in the continuous aqueous phase of the emulsions and yoghurts were calculated at the TRTC. The styrene concentrations in the continuous phase had constant values of about 15 g kg^?1 indicating that perception of styrene for oil-in–water emulsions is determined by the aqueous phase of the emulsion. The concentrations of styrene in the vapor phases above the emulsions and yoghurts were also calculated and were found to be constant at the TRTC. This relationship probably resulted from the equilibrium of distribution of styrene between the respective phases. Commercial yoghurt packed in polystyrene beakers contained styrene levels in the range 2–11 g kg^?1, much lower then the TRTC reported.     

基于神经网络的智能检索系统

文章首先概述了当前大多数的搜索引擎的主要的弊端；然后着重介绍了智能检索系统的运行基本思路和售用算法，以及该算法在检索领域中运用的优点；最后指出，神经网络运用在检索领域，可解决网络管理中的诸多难题。     

The geographies of a more just food system: Building landscapes for social reproduction

Within the lifetime of a generation of people now involved in work in the cattle and beef industry in South Dakota, the landscapes of social reproduction that support and give shape to life for people there have been rearranged. Many of the social and physical relationships that developed to support smaller-scale, diverse farms and their surrounding communities are being made redundant by a new system of beef production and retailing. The costs of these redundancies are felt in dwindling small towns and an ever sparser rural population. Considering these changes as parts of landscapes of social reproduction is a means to connect the political and corporate logic driving our food systems to the spatial production of difference in the conditions for livelihood, as well as the spatial production of livelihood itself for both producers and consumers. Such an analysis is necessary in order to address the injustices inherent within our current food system.     

Intelligent scheduling with tabu search: An application to jobs with linear delay penalties and sequence-dependent setup costs and times

In this article we study thetabu search (TS) method in an application for solving an important class of scheduling problems. Tabu search is characterized by integrating artificial intelligence and optimization principles, with particular emphasis on exploiting flexible memory structures, to yield a highly effective solution procedure. We first discuss the problem of minimizing the sum of the setup costs and linear delay penalties when N jobs, arriving at time zero, are to be scheduled for sequential processing on a continuously available machine. A prototype TS method is developed for this problem using the common approach of exchanging the position of two jobs to transform one schedule into another. A more powerful method is then developed that employs insert moves in combination with swap moves to search the solution space. This method and the best parameters found for it during the preliminary experimentation with the prototype procedure are used to obtain solutions to a more complex problem that considers setup times in addition to setup costs. In this case, our procedure succeeded in finding optimal solutions to all problems for which these solutions are known and a better solution to a larger problem for which optimizing procedures exceeded a specified time limit (branch and bound) or reached a memory overflow (branch and bound/dynamic programming) before normal termination. These experiments confirm not only the effectiveness but also the robustness of the TS method, in terms of the solution quality obtained with a common set of parameter choices for two related but different problems.     

Optimal search for signals in a multichannel system: Arbitrary initial distribution in state space merging scheme

Markovian and semi-Markovian random processes are used to analyze the problem of optimal search for signals in a multichannel communication system with arbitrarily distributed random outputs. The search efficiency factor is found in explicit form based on state space merging, and a mathematical programming problem is set up to find a numerical suboptimal solution. __________ Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 144–150, May–June 2007.     

Cubic Bézier approximation of a digitized curve

In this paper we present an efficient technique for piecewise cubic Bézier approximation of digitized curve. An adaptive breakpoint detection method divides a digital curve into a number of segments and each segment is approximated by a cubic Bézier curve so that the approximation error is minimized. Initial approximated Bézier control points for each of the segments are obtained by interpolation technique i.e. by the reverse recursion of De Castaljau's algorithm. Two methods, two-dimensional logarithmic search algorithm (TDLSA) and an evolutionary search algorithm (ESA), are introduced to find the best-fit Bézier control points from the approximate interpolated control points. ESA based refinement is proved to be better experimentally. Experimental results show that Bézier approximation of a digitized curve is much more accurate and uses less number of points compared to other approximation techniques.