腐蚀钢质烟囱剩余强度有限元分析与加固措施研究

蜀南气矿净化厂尾气烟囱为内砌耐火砖的钢质烟囱,在长期使用过程中,由于尾气残存硫和其他腐蚀物质综合作用,已经严重腐蚀和老化,不能维持简单再生产和扩大再生产的需要,必须立即采取加固措施。针对该烟囱具体腐蚀缺陷,进行可靠性鉴定。通过大量的计算机模拟和剩余强度的有限元计算,找出了烟囱的薄弱环节和对几种加固方案进行了比较分析,最终得出可靠的加固方案。为企业取得了显著的经济效益和社会效益。     

PRA using event tables and the Brookhaven event tree analyzer (BETA)

Event trees are key elements in applying PRA in pre-conceptual design for safety enhancement of Oak Ridge National Laboratory's Advanced Neutron Source (ANS) research reactor which will be the world's best source of low-energy neutrons for material studies, physics research, transplutonium production and radiation effects. Event trees exhaustively explore the combinations of system failures that may follow from accident initiator through dendritic diagrams connecting initiator with plant damage state and by calculating the frequency of each accident sequence. They are the central element of PRA, but require supplementary text to relate the sequences to plant systems, explain the logic and state assumptions. These tasks are accomplished by the integration of a popular word processor and the event tree analysis code BETA. Using the worl processor, the analyst writes text that describes each sequence to a depth deemed necessary and prepares an Event Table which indicates by symbols the operability of each system in the accident sequence and the judged fuel damage state. The matrix of symbols so formed is copied to another file, edited to remove spaces, additional information is added and the file is saved in ASCII format to provide input to BETA. BETA, which may be used for further editing, displays or plots on HP laser or Epson printer, the event tree specified by the Event Table logic and computes, displays and/or prints the end or intermediate state probabilities according to damage criteria. It also provides for changing nodal probabilities within the event tree according to the preceding sequences (‘binary conditionals’). The size of event trees is essentially unlimited by its ability to branch and link with other event trees. Work sessions may be saved to floppy or hard disk for recall. This paper describes how to use BETA, and how it works.     

基于ANSYS技术的双轴对称工字型截面梁优化设计

双轴对称工形截面钢梁在土木工程中有着广泛的应用,对这种受弯构件的设计目前采用的是试算法,在进行结构设计时,往往需要进行大量的计算工作。根据优化设计原理给出梁优化设计的数学模型,利用通用有限元计算软件ANSYS对某平台梁进行优化实例分析,得出优化结果,并根据优化结果提出构件设计的建议。     

数码涡旋空调的应用研究

武汉市政府办公大楼是一座集办公、餐饮于一体的现代化办公楼建筑,该建筑采用了最新的数码涡旋变制冷剂流量多联分体式空调系统,新风系统设计采用全热交换器处理独立送入空调房间,本文从空调系统的设计到应用,详细介绍了数码涡旋空调系统的应用与效果分析,同时也对本工程的不足进行剖析,以便在以后类似的空调系统设计中能够很好地解决.     

Optimization Models for Scheduling of Jobs

This work is motivated by a particular scheduling problem that is faced by logistics centers that perform aircraft maintenance and modification. Here we concentrate on a single facility (hangar) which is equipped with several work stations (bays). Specifically, a number of jobs have already been scheduled for processing at the facility; the starting times, durations, and work station assignments for these jobs are assumed to be known. We are interested in how best to schedule a number of new jobs that the facility will be processing in the near future. We first develop a mixed integer quadratic programming model (MIQP) for this problem. Since the exact solution of this MIQP formulation is time consuming, we develop a heuristic procedure, based on existing bin packing techniques. This heuristic is further enhanced by application of certain local optimality conditions.     

Sensitivity of trends in geometric mean blood levels to random measurement errors

A statistical model is investigated that expresses observations, such as blood lead levels, as an additive function of true levels and random measurement errors. Both empirical results (obtained from a series of computer simulation experiments) and theoretical results indicate how certain summary statistics for the observations vary in response to random measurement errors. Such results are applied to a very large data base of pediatric blood lead levels collected in New York City during 1970–1976, and they indicate that the observed trends in geometric mean blood lead levels are not significantly altered by the possible presence of measurement errors.     

Distribution of aflatoxins in shelling and milling fractions of naturally contaminated rice

The objective of this study was to determine the distribution of an economically important class of mycotoxins, the aflatoxins, in rice milling fractions. Rice plants grown under field production conditions are frequently infected with types of pathogenic fungi that produce toxic metabolites (mycotoxins). Paddy (seeds) rice from healthy plants in the field was collected and stored on a farm under humid, poorly ventilated conditions. Samples were milled into four fractions (hulls, brown rice, bran and white rice) and analysed for aflatoxins (B(1), B(2), G(1) and G(2)) using a validated method. Rice fractions from healthy plants, which contained low levels of aflatoxins (less than 1?μg?kg(-1)), were used to determine the efficiency of the extraction method. Seeds stored under poor conditions were found to be contaminated with aflatoxins B(1) and B(2) as were the fractions. The sums of AFB(1) and AFB(2) in stored paddy rice, hulls, brown rice, bran and white rice were 141, 39, 158, 367 and 56?μg?kg(-1), respectively. The ratio of aflatoxin B(1) and B(2) was about 10?:?1. AFG(1) and AFG(2) were less than 1?μg?kg(-1). Thus, brown rice contained 92.9% of the aflatoxins in paddy rice, whereas white rice contained only 27.9%.     

Fat embolism prophylaxis: a study of four treatment modalities

Significant coagulation and blood gas changes may occur with uncomplicated extremity fractures. To more accurately define the effect of therapy on these changes, a prospective study of 58 patients with uncomplicated fractures was undertaken. An initial group of 10 selected patients was studied to determine the changes with "standard therapy." The remaining 48 patients were then randomized into five groups: control, increased fluid intake, increased glucose intake, aspirin, and massive steroids. The patients were studied on 5 consecutive days. Treatment of patients in the latter four groups with aspirin or steroids resulted in significant normalization of blood gases, coagulation proteins, and platelet numbers when compared to controls. These measurements in patients treated with fluid loading or increased glucose intake were not significantly different from controls.     

无侧位移楔形变截面门式刚架柱弯矩作用平面内的等效弯矩系数研究

现行规范CECS 102∶2002《门式刚架轻型房屋钢结构技术规程》对楔形变截面刚架柱的稳定计算公式(6.1.3-1)借鉴等截面构件的稳定计算公式,但平面内等效弯矩系数仅对有侧移刚架柱作出规定βm=1,而对于无侧移楔形变截面刚架柱平面内等效弯矩系数未作任何规定,这给设计和工程实践带来了不便。本文基于平衡法,对3类典型受力情况下无侧移楔形变截面门式刚架柱平面内等效弯矩系数进行了深入研究,并取得一些有价值的研究成果,可为工程实践及规范修订提供参考。     

高压异常地层局部双层组合套管的设计与应用

中原油田的套管损坏问题，在全国各油田中是较为严重的，影响了中原油田稳定的战略目标。为此，中原石油勘探局与西南石油学院合作，开展了近１ａ多的联合攻关研究，在盐层高压的形成机理，超高压地层套管外挤力计算，局部双层组合套管的设计及套管寿命预测方法研究等方面，理论上获得重大突破。