A computational study of LP-based heuristic algorithms for two-dimensional guillotine cutting stock problems

In this paper we develop and compare several heuristic methods for solving the general two-dimensional cutting stock problem. We follow the Gilmore-Gomory column generation scheme in which at each iteration a new cutting pattern is obtained as the solution of a subproblem on one stock sheet. For solving this subproblem, in addition to classical dynamic programming, we have developed three heuristic procedures of increasing complexity, based on GRASP and Tabu Search techniques, producing solutions differing in quality and in time requirements. In order to obtain integer solutions from the fractional solutions of the Gilmore-Gomory process, we compare three rounding procedures, rounding up, truncated branch and bound and the solution of a residual problem. We have coded and tested all the combinations of algorithms and rounding procedures. The computational results obtained on a set of randomly generated test problems show their relative efficiency and allow the potential user to choose from among them, according to the available computing time. Rceived: January 9, 2001 / Accepted: December 10, 2001     

Non-contact methods of measuring moisture concentration in external layers of building partitions: III—Water vapour condensation on the cementitious surfaces

This paper presents the results of the larger study into a potential application of laser radiation for the detection of phase transition processes in low temperatures occurring on the surface layers of cementitious materials. An attempt was made to identify relationships between the environmental conditions—temperature and air humidity, and the selected parameters of the reflected light. Onset of the condensation process and formation of water microdrops on the surface of the material leads to the phase displacement of individual laser rays, which are represented by different speckle images.

Although the analysis of parameters of the reflected light are very difficult in the case of porous materials because of highly developed roughness of the surface structure it has been proved that a dynamic study of the phase transition phenomena can be successfully carried out without mechanical intervention.     

50W CO_2激光雕刻机控制系统

介绍非金属材料表面加工的CO2激光雕刻机的基本原理其控制系统。     

RS码频域纠错编码在激光对潜通信信道中的实现方法

介绍了信道编码在激光对潜通信系统中的重要作用，介绍了频域编译ＲＳ码的基本方法，并给出了脉冲位置调制信道的ＲＳ码频域编译码的计算机模拟方法和结果。     

硅片和硅器件工艺中的背面损伤吸除技术

本文介绍了硅片背面的三种主要损伤吸除技术：机械损伤、激光辐照和离子注入技术。对这三种吸除技术的机理、工艺条件、应用情况和近来进展，作了详细的评述。     

对微弱激光辐射的探测

由于面临越来越严重的激光制导武器的威胁 ,对来袭威胁进行早期预警日趋重要。概要介绍了微弱激光辐射探测技术国外研究现状及发展趋势。对微弱激光辐射探测关键技术进行了研究探讨。     

Pulsed KrF excimer laser annealing of silicon solar cell

The pulsed KrF excimer laser annealing of silicon films for solar cell with EBEP-CVD and LP-CVD was studied theoretically and experimentally. Three-dimensional thermal diffusion equation for microcrystalline and amorphous silicon was solved by using the finite difference methods. The results of our heat-flow simulation of laser re-crystallization in a laser irradiation with 50 ns pulse duration almost agree with the experimental results in re-crystallization depth of 0.7 μm for microcrystalline silicon (EBEP-CVD) and 0.4 μm for amorphous silicon (LP-CVD) in a single pulse excimer laser annealing.     

Non-contact methods of measuring moisture concentration in external layers of building partitions II—Monitoring of the water vapour condensation on porous surfaces

This paper present the results of the investigation into a potential application of laser radiation for the detection of phase transition processes occurring on the surface layers of porous materials. An attempt was made to discuss in the approximation equations, the relationships between coefficients of the reflected light, the temperature and humidity of the surrounding environment. Laser light reflected from the porous surface carries information about the roughness of the structure. The presence of water microdrop on the surface of the porous material, as a result of condensation and thus a phase transition, leads to the phase displacement of individual rays, which is represented by different images. Therefore, a comprehensive analysis of the reflected light parameters allows a dynamic study of the phase transition phenomena without mechanical intervention.     

激光远距作用的机制与效应

本文定量分析激光远距作用的机理并对它们在治癌中的作用作简要的论述。