管道突然扩大局部阻力系数初探

在管道设计中 ,经常遇到局部阻力系数确定的问题。突然扩大局部阻力系数ξ1=1 - A1 / A2 2是通过理论确定的。通过对三种 A1 / A2 情况下的局部阻力系数的实验研究 ,结果发现ξ不但与两过流断面有关 ,而且还和流速有关。通过实验研究 ,确定了ξ1 与流速 v1 及A1 / A2 之间的关系 ,在设计中 ,只要根据设计流速 v1 与 A1 / A2 就可以采用相应的ξ1 进行管道的水力计算     

鞍山市区地下水引起地面塌陷研究

鞍山市区当前出现的地面塌陷是潜蚀型岩溶地面塌陷,只在特大丰水年个别地段发生。但在铁西水源地水位降落漏斗范围内,如继续过量开采地下水,尤其是隐伏裂隙岩溶承压水,当地下水位降至隐伏灰岩顶板以下时,将出现多发性真空吸蚀地面塌陷,其危害不堪设想。根据鞍山市区岩溶地面塌陷发生的机理,提出相应治理措施。     

多水下机器人视景仿真系统技术研究

该文介绍了多水下机器人群体分佰式智能控制软件的视景仿真系统。以MultiGen Creator建模,利用实时视景开发软件包OpenGL Performer,采用POSIX Thread多线程技术,在Linux环境下开发了分布式多水下机器人三维视景仿真平台。实现了多水下机器人分布式智能控制软件系统的实时视景仿真,保证了整个系统的信息共享与时间同步。同时该文讨论了该视景仿真软件的开发过程以及整个系统的体系结构和信息流程。试验结果表明,该视景系统可逼真演示多水下机器人编队水下航行、作业等过程,并满足系统仿真的实时性要求。     

集成电路封装工艺生产管理系统的设计与实现

针对集成电路封装工艺生产的实际需要,设计和实现了一个基于客户机/服务器模式的集成电路封装工艺生产管理系统.该系统可以采集大量的生产数据信息,并自动完成统计分析,生成各种实时的报表;特别是增加了用户自定义报表编缉功能,使得管理者和工程师能够快速地生成自己所需形式的报表,统计分析生产流水数据,提高生产的工艺管理水平.目前,系统性能已经过测试优化并投入试运行.     

网络聚合技术在高性能地震资料处理系统中的应用

根据近年来中海油南海西部油田地震勘探资料高性能并行处理系统建设的成功案例,详细地介绍几个基于偏移技术计算的有代表性的HPC集群并行处理系统网络架构模型(包括千兆或万兆以太网和存储网络)的演变、趋势和技术特点,以及不同的网络在新建集群和系统扩充中整合与汇聚。     

提高中厚板圆盘剪剪切能力的分析及对策

圆盘剪剪切范围的大小直接影响着库区物流的周转、生产成本和合同周期等各项指标,同时也直接反映精整工序的生产能力。分析影响圆盘剪剪切能力的几大制约因素,并提出提高剪切范围的对策。     

不同稀土含量的GDL-1钢中贝氏体相变研究

在不同稀土含量的GDL-1钢中,采用不同温度下中断空冷淬火的方法研究稀土对低碳合金贝氏体钢中贝氏体相变的影响。稀土含量增加,Bs点由380℃降为350℃,残留奥氏体量的增多,贝氏体铁素体的体积分数减小,显微硬度值略微升高。稀土对贝氏体激发形核和台阶生长之间的竞争也产生了重要的影响,增加稀土的量,贝氏体亚结构的细化程度更加明显,细小的亚片条、亚单元之间被稳定的残留奥氏体薄膜所分割,最终形成贝氏体多层次精细结构。     

Developing methods of controlling the structure and properties of cold-rolled steel to increase usable output and stabilize mechanical characteristics

Recommendations have been developed on optimizing hot rolling in the finishing train of a 2000 mill and subsequent coiling of the rolled product. The goal was to improve the stampability characteristics of steel 08Yu. Specific recommendations were also made on the optimum annealing and temper-rolling regimes to improve the mechanical characteristics of steel 08Yu. The results of studies show that the structure and properties of the cold-rolled product are significantly affected by the conditions of precipitation of different particles of nonmetallic inclusions. It is shown that it would be expedient to analyze the thermodynamics and kinetics of these processes and study the morphology of the particles and the state of the solid solution. Recommendations on chemical composition and process parameters that were developed on the basis of the results of such analysis are now making it possible to consistently obtain steel 08Yu with high properties. __________ Translated from Metallurg, No. 2, pp. 51–59, February, 2007.     

An efficient approach to incorporating interfraction motion in IMRT treatment planning

Intensity modulated radiation therapy (IMRT) is one of the most widely used delivery modalities for radiation therapy for cancer patients. A patient is typically treated in daily fractions over a period of 5-9 weeks. In this paper, we consider the problem of accounting for changes in patient setup location and internal geometry between the treatment fractions, usually referred to as interfraction motion. The conventional method is to add a margin around the clinical tumor volume (CTV) to obtain a planning target volume (PTV). A fluence map optimization (FMO) model is then solved to determine the optimal intensity profiles to deliver to the patient. However, a margin-based method may not adequately model the changes in dose distributions due to the random nature of organ motion. Accounting for interfraction motion in the FMO model essentially transforms the deterministic optimization problem into a stochastic one. We propose a stochastic FMO model that employs convex penalty functions to control the treatment plan quality and uses a large number of scenarios to characterize interfraction motion uncertainties. Some effects of radiotherapy are impacted mainly by the dose distribution in a given treatment fraction while others tend to manifest themselves over time and depend mostly on the total dose received over the course of treatment. We will therefore formulate an optimization model that explicitly incorporates treatment plan evaluation criteria that apply to the total dose received over all treatment fractions and ones that apply to the dose per fraction. Particularly when many structures fall into the former category, this can lead to significant reductions in the dimension of the optimization model and therefore the time required to solve it. We test an example of our model on five clinical prostate cancer cases, showing the efficacy of our approach. In particular, compared to a traditional margin-based treatment plan, our plans exhibit significantly improved target dose coverage and clinically equivalent critical structure sparing at only a modest increase in computational effort.     

A recursive embedding algorithm towards lossless 2D vector map watermarking

The copyright protection of two-dimensional (2D) vector map has attracted a lot of research focus due to the increasing security issues raised in recent years. One promising direction seeking the optimal tradeoff between adding watermarks and maintaining minimal distortion is the so-called lossless watermarking, i.e., after watermark extraction the 2D vector maps are fully lossless. This paper presents a novel lossless watermarking scheme for 2D vector maps based on a novel recursive embedding algorithm. In our algorithm, feature points of individual polylines are first grouped into united, upon which highly correlated unites are selected as cover data to carry out a recursive modification of its mean vertex coordinates. Such operation not only ensures lossless compression, but also enables higher payload capacity and, to a certain degree, the perception invisibility before and after the watermark extraction. We have conduced experiments on several real-world 2D vector map applications to show the effectiveness, efficiency of the proposed algorithm.