Evaluation of a parallel branch-and-bound algorithm on a class ofmultiprocessors

We propose and evaluate a parallel “decomposite best-first” search branch-and-bound algorithm (dbs) for MIN-based multiprocessor systems. We start with a new probabilistic model to estimate the number of evaluated nodes for a serial best-first search branch-and-bound algorithm. This analysis is used in predicting the parallel algorithm speed-up. The proposed algorithm initially decomposes a problem into N subproblems, where N is the number of processors available in a multiprocessor. Afterwards, each processor executes the serial best-first search to find a local feasible solution. Local solutions are broadcasted through the network to compute the final solution. A conflict-free mapping scheme, known as the step-by-step spread, is used for subproblem distribution on the MIN. A speedup expression for the parallel algorithm is then derived using the serial best-first search node evaluation model. Our analysis considers both computation and communication overheads for providing realistic speed-up. Communication modeling is also extended for the parallel global best-first search technique. All the analytical results are validated via simulation. For large systems, when communication overhead is taken into consideration, it is observed that the parallel decomposite best-first search algorithm provides better speed-up compared to other reported schemes     

空气压缩机实时监控系统

介绍一种以工业控制机为核心的空气压缩机实时监控系统。为防止电磁干扰，系统采取了有效的隔离保护措施。论述了系统结构、工作原理和硬软件配置。     

核电材料在模拟反应堆环境中应力腐蚀破裂测试技术与性能评价

简要介绍了采用慢应变速率试验，Ｕ型弯曲和Ｃ形环试验等技术，分别对８００合金，３０４和３１６及３１６Ｔｉ不锈钢Ａ５３３Ｂ压力容器用多在模拟核反应堆环境中的应力腐蚀破裂敏感性性进行的试验研究的一些主要结果；并结合电化学测试和表面膜俄歇电子能谱分析结果进行了讨论。     

CA／PAN中空纤维血浆分离膜的结构与性能

本研究以CA及PAN的共混溶液,通过干-湿法纺丝制取中空纤维,利用共混高聚物各组分在凝固剂中相分离速度的差异,形成具有稳定结构的中空纤维孔膜,该膜用于分离血液中的血浆成分具有良好效果。讨论了成型条件及添加剂等对膜结构、性能的影响,用SEM及图相分析仪、MAP压汞仪及DSC等分析手段,对膜的微孔结构、形态、孔尺寸及中空纤维膜的血浆通量和水通量等进行了系统的考查。     

Finite-difference time-domain simulation of scattering from objectsin continuous random media

A three-dimensional (3D) finite-difference time-domain (FDTD) scheme is introduced to model the scattering from objects in continuous random media. FDTD techniques have been previously applied to scattering from random rough surfaces and randomly placed objects in a homogeneous background, but little has been done to simulate continuous random media with embedded objects where volumetric scattering effects are important. In this work, Monte Carlo analysis is used in conjunction with FDTD to study the scattering from perfectly electrically conducting (PEC) objects embedded in continuous random media. The random medium models under consideration are chosen to be inhomogeneous soils with a spatially fluctuating random permittivities and prescribed correlation functions. The ability of frequency averaging techniques to discriminate objects in this scenarion is also briefly investigated. The simulation scheme described in this work can be adapted and used to help in interpreting the scattered field data from targets in random environments such as geophysical media, biological media, or atmospheric turbulence     

利用反射纵波评价裂缝倾角的模拟实验研究

声波全波列测井中的反射纵波可以用来评价高角度裂缝和对井周附近地质结构进行成像。目前的研究主要侧重于直接从波形资料处理出发计算裂缝的位置和倾角 ,其可靠性和准确性无从评价和校验。文中采用模拟实验的方法记录了倾角为 6 0°～80°范围内的 8种倾角裂缝的反射脉冲纵波波形 ,自行推导了反演裂缝倾角的公式 ,结合波场分离技术对实验测量波形数据进行了处理 ,计算出的裂缝倾角与实际值具有良好的一致性。本文结果表明 ,利用至少 2个深度点的纵波反射波波形资料就可以准确地反演裂缝的倾角     

孤岛油田西区聚合物驱开发研究

孤岛油田西区注聚区1997年3月投入注聚后，高渗层得到有效封堵，吸水剖面得到明显改善。注聚期间，通过实施注聚区外围水井降水或停注、油井放大生产压差和调整注聚井注入速度等开发措施，扩大了聚合物波及体积，聚合物驱取得了明显效果。     

PTA装置压力离心机冲洗新技术

分析了仪征化纤PTA装置压力离心机运转效果不佳的原因,提出解决方案,改造实施后取得了很好的效果。     

万家寨引黄工程北干线输水损失分析

万家寨引黄工程北干线系统输水损失，是关乎输水运行成本和水资源有效利用的重要问题之一。由于各类建筑物施工方法，材料及工艺的差异。其输水损失差异较大，计算方法和计算参数各不相同，文章在对各类建筑物进行输水损失计算的基础上，分析了不同类型建筑物的输水损失特点，提出了减少水量损失的建议和设想。     

宽带无源光网络(BPON)关键技术的发展与研究

宽带无源光网络（BPON）是实现宽带、多业务接入的理想物理平台，本文介绍了BPON网络的发展，重点讨论了将ATM技术和PON技术相结合的APON系统及其升级系统SuperPON的基本结构和关键技术，对最近兴起的将以太技术和PON技术相结合的EPON系统的基本概念和工作原理也进行了阐述，并对未来BPON技术的发展进行了展望。