钢筋砼结构的耐久性分析

钢筋砼结构的耐久性是工程结构的基本功能之一,本文分析了影响耐久性的一些主要因素:钢筋锈蚀、盐污染、碱—集料反应、冻融破坏的机理,指出了目前规范和生产中存在的一些问题,同时用工程实例阐明了上述因素对工程的破坏.     

钛型不锈钢焊条渣壁过渡形成条件的探讨

渣壁过渡是焊条金属熔滴理想的过渡形态。本文探讨了形成渣壁过渡的两个基本条件,并提出了钛型不锈钢焊条药皮成分,焊条外径影响熔滴过渡形态的关系图,以判断此类不锈钢焊条熔滴过渡形态,并指导其配方设计。     

Microsatellite polymorphisms of Sichuan golden monkeys

Previous study using protein electrophoresis shows no polymorphism in 44 nuclear loci of Sichuan golden monkey （Rhinopithecus roxellana）, which limits our understandings of its population genetic patterns in the nuclear genome. In order to obtain sufficient information, we scanned 14 microsatellite loci in a sample of 32 individuals from its three major habitats （Minshan, Qinling and Shennongjia）. A considerable amount of polymorphisms were detected. The average heterozygosities in the local populations were all above 0.5. The differentiations among local populations were significant. There was evidence of geneflow among subpopulations, but geneflow between Qinling and Shennongjia local populations was the weakest. Minshan and Qinling populations might have gone through recent bottlenecks. The estimation of the ratio of the effective population sizes among local populations was close to that from census sizes. Comparisons to available mitochondria data suggested that R. roxellana＇s social structures played an important role in shaping its population genetic patterns. Our study showed that the polymorphism level of R. roxellana was no higher than other endangered species; therefore, measures should be taken to preserve genetic diversity of this species.     

光动力学法测定食盐中碘化物

在酸性介质中加入过量的硫代硫酸钠,与试液中的碘酸盐反应.用被光(紫外光)激活的溶液中之碘化钾产生的碘滴定剩余的硫代硫酸钠.结果表明,到达终点的时间与碘酸盐的含量成比例,线性范围为0～100μg/20mL,RSD为2.08％,标准加入回收率96％～106％.     

基于Taylor级数模型最小二乘滤波器设计

本文提出了一种基于被测函数Ｔａｙｌｏｒ级数展开式的最小二乘滤波器的设计方法，这种滤波器可以用一个有限冲激响应滤波器来实现，有很大的实用价值，它不仅可以用于对测量信号的滤波，而且同时可以对异常数据测量点进行插值，这种方法还可以推广到对测量信号的一阶和高阶导数进行最小二乘估计。计算机模拟和实际使用都证明，这是一种有效的滤波器，它可以有效地滤除混杂在接收信号中的噪声，大大改善测量效果。     

全胃切除术后三种消化道重建方式预防反流性食管炎的效果比较

目的 评估全胃切除术后三种消化道重建方式预防反流性食管炎的效果.方法 统计分析2002～2007年行全胃切除无瘤生存1年以上的96例胃癌患者,分别采用袢式空肠代胃+Brmm吻合(Brsun)、单纯Roux-en-Y吻合(RY)和Roux-en-Y吻合+P形代胃(RYP)三种方式重建消化道,对这些患者资料进行回顾性分析,以术后的消化道症状和营养状况作为评价依据.结果 Braun组存在严重的食管反流,RY和RYP重建则有较强的抗反流作用,RYP组饮食限制少、进餐早期饱足感发生少;术后半年时无瘤生存患者的营养状况三组无差异,而1年以后体重恢复和血浆总蛋白水平RY和RYP两组优于Braun组.结论 Braun吻合术后食管反流严重、营养状况较差;而RY及在此基础上的P形代胃术效果良好,是比较合适的重建术式,建议对预期术后生存期超过1年以上患者,采用P形代胃术.     

基于遗传算法神经网络的地源热泵夏季低负荷运行性能预测分析

为了探索夏热冬冷地区岩溶地质条件下地热能应用能效,通过运用遗传算法优化的反向传播（GA-BP）神经网络模型预测了夏季系统负荷率低于30%运行工况下地源热泵系统的系统能效比和机组能效比,分析了预测值的预测误差评价指标,验证了GA-BP模型具有较高的预测精度,并应用此模型研究了地源热泵短期能效测试与中长期能效测评的关系。结果表明,GA-BP模型预测的COPsys及COP与计算值的相对误差为±5%,各项预测误差评价指标均比反向传播神经网络（BPNN）模型更小,可见GA-BP模型可用于预测岩溶地质条件下地源热泵系统能效。基于此模型,短期能效测试的最佳时期为一天中14时~16时或7、8月累计13天,且满足机组负荷率达到60%~70%,COPsys及COP预测值可以作为中长期能效比评估,其产生的相对误差在允许的范围内。     

Optimized body structure and packagingfor car ODB impact performance

Front bumper,crash box and side rail are key body structural parts in front crash.Deformation space is affected by compartment packaging.The improvement suggestions are proposed to solve the problems existed in the current vehicle structure and compartment packaging based on the areas that influence performance of automobile offset deformable barrier impact, such as the side rail,mounting,storage battery packaging,etc.It is proved that 40%offset crash simulation result of one certain car is well-correlated with the physical test.Optimization cases meet the crash performance requirements.The objective of the analysis is to guide structural design and improves a car’s crash safety performance.     

基于化学动力学和包裹体分析技术研究川东石炭系成藏史

川东石炭系油气藏的源岩生烃史及运聚史研究的不够充分,缺少定量化的动态指标依据,影响了川东石炭系新的接替区域的勘探。利用化学动力学方法对其主力烃源岩下志留系泥岩进行生烃史模拟,同时结合包裹体分析技术进行流体注入史研究,分析二者的匹配关系,模拟石炭系油气藏的动态调整过程。研究认为石炭系油气藏为三期成藏,第一期晚二叠世~晚三叠世,下志留统烃源岩早成熟阶段,开始初步生气,形成早期的小规模天然气藏;第二期晚三叠~早侏罗世时期,为烃源岩大量生油阶段,形成古油藏;第三期燕山时期,古油藏遭遇高温裂解生气阶段,并经历后期的调整改造,最终形成现今的气藏分布。显示化学动力学和包裹体分析技术可有效提高油气藏成藏史的模拟精度。     

Thermal stability conditions of a weakly interacting Fermi gas in a weak magnetic field

On the basis of the results derived from pseudopotential method and ensemble theory, thermal stability of a weakly interacting Fermi gas in a weak magnetic field are studied by using analytical method of thermodynamics. The exact analytical expressions of stability conditions at different temperatures are given, and the effects of interactions as well as magnetic field on stability of the system are discussed. It is shown that there is an upper-limit magnetic field for the stability of the system at low temperatures and there is an attractive dividing value at high temperatures. If attractive interaction is lower than the critical value, the stability of the system has no request for magnetic field, but if attractive interaction is higher than the dividing value, a lower-limit magnetic field exists for the stability of the system.