接触网部件材料在模拟典型大气环境介质中的腐蚀—铝合金材料的腐蚀(Ⅱ)

本文研究了铝合金接触网构件材料在模拟典型大气环境中的腐蚀,结果表明,在不同大气环境中,铝合金在城市环境中的腐蚀性最强,其次是工业环境,海洋环境腐蚀性最弱。接触网构件表面的局部破损会引起腐蚀加重,且破损面积越大腐蚀越严重。而接触网构件和不锈钢偶接形成电偶腐蚀,较大程度的加重了接触网的腐蚀。     

基于熵权与TOPSIS融合法的绿色刀具制造方案评估模型研究

基于绿色制造理念的刀具方案评估是推动机械加工行业实现绿色制造的重要措施。针对现有面向绿色制造的刀具方案评价研究中评价指标权重确定方面存在的不足,提出了一种新的熵权法和TOPSIS法相结合的绿色制造刀具方案评估方法。首先建立了多层次的绿色制造刀具方案评估指标体系,在此基础上,将熵权法与TOPSIS法相结合建立了基于熵权TOPSIS法的绿色制造刀具方案评估模型。最后通过方案评估实例验证了所建立的绿色制造刀具方案评估模型是合理有效的。     

A new approach for evaluating lateral resistance of railway ballast associated with extended sleeper spacing

Recently, attempts have been made to replace wooden sleepers with concrete sleepers with expanded sleeper spacing, especially on conventional railway lines. By extending sleeper spacing in the replacement process, the number of sleepers required is lower. A reduction in the number of sleepers can reduce replacement costs. Behind this attempt to change materials and spacing is the generally held notion the lateral resistance of a ballast is unchanged after the change in the sleeper spacing, whether it is a wooden or a concrete sleeper. However, the changes in the interference degrees of adjacent sleepers and in the rail weight supported by each sleeper are expected to affect the lateral resistance of the ballast. They can change the lateral stability of ballasted tracks in a more complicated fashion than the simple effect of a reduced number of sleepers. However, the current standard design does not consider the combined effects of these changes on the lateral resistance of a ballast. Accordingly, the design of ballasted tracks with extended sleeper spacing cannot be optimized.Therefore, the aim of this study was to investigate the lateral resistance characteristics of a ballast as associated with changes in the sleeper spacing of conventional railway lines. First, single-sleeper pullout tests were conducted on models based on various sleeper spacing conditions to evaluate the lateral resistance of the ballast. The effect of the rail weight on the lateral resistance of the ballast was determined from the test results. An increased frictional resistance at the sleeper bottom was considered to contribute to an increase in the lateral resistance; thus, the friction angle between the ballast and sleeper bottom was used to evaluate the degree of increase. Subsequently, track panel pullout tests were conducted by simulating an expansion of the sleeper spacing. Based on the test results, the effect of the interference between adjacent sleepers on the lateral resistance per sleeper was investigated. The obtained results were quantitatively modeled as a function by using the sleeper width as a parameter (as normalized by the sleeper spacing). Finally, a new approach was proposed for estimating the lateral resistance of a ballast which considered the change in the sleeper spacing for conventional railway lines. The method considered the combined effects of change in the interference of adjacent sleepers and in the rail weight supported by each sleeper on the lateral resistance. Based on the results calculated by the proposed method, practical applications were examined by determining the extent to which the sleeper spacing could be increased without reducing the lateral resistance of the ballast when replacing wooden sleepers with concrete sleepers. It was demonstrated that the proposed method could improve the estimation accuracy of the lateral resistance of a ballast track with extended sleeper spacing.     

核磁共振氢谱法在聚羧酸减水剂大单体表征中的应用

对常见的4种聚氧乙烯醚大单体进行了核磁共振氢谱法(1HNMR)分析,并以此为依据建立了1HNMR技术快速、准确地检测大单体的方法,实现对聚羧酸减水剂中残留大单体的定性分析。采用该法,确认了各大单体1HNMR的谱峰归属,并根据大单体的特征峰计算其数均分子量大小。同时,利用1HNMR法对聚酯类减水剂的酯化反应中酯化率和双键保留率两个重要指标进行测定。结果表明,该法准确、快速、简便,适用于聚羧酸减水剂中大单体的快速鉴定。     

基于工程认证标准要求的课程权重系数计算方法分析

建筑环境与能源应用工程是以培养学生能够从事工业与民用建筑环境控制和能源供应为主的工程应用性专业,根据工程认证标准要求,建环专业的毕业要求控制指标点各因素应根据培养目标和课程体系进行权重系数计算。目前,由于工程认证在我国开展时间不长,专业教师还缺少对相关权重系数计算方法的认识、理解和掌握。这不利于教学开展,也不符合工程认证条件下专业的发展要求。在工程认证标准基础上,对建环专业的毕业要求指标点与支撑课程之间的关系进行了分析,利用层次分析法通过构建指标点和支撑课程的层次结构模型,建立其判断矩阵,并对各指标点因素的权重系数进行了计算分析,获得了毕业要求不同指标点的权重系数,并对其计算结果进行了分析讨论;同时,将层次分析法与学分法得到的权重系数进行了比较分析,指出了每种计算方法存在的优缺点,以期对建环专业的工程认证起到促进作用。     

2010年广西正常体重成年人中心型肥胖流行状况分析

目的：了解广西正常体重人群中心型肥胖流行状况及分布特点。方法利用中国慢性病及其危险因素监测项目问卷调查及身体测量获得的数据,分析广西6个监测点18岁以上体重正常人群2244人中心型肥胖的流行情况,以及体重正常人群中心型肥胖与心血管疾病危险因素聚集的关系。结果体重正常成人中,按照腰围、腰围身高比划分的中心型肥胖率分别为7.3％和16.6％,均为女性高于男性（P值均＜0.01）并随着年龄的增加而上升;按照腰围划分,城市地区中心型肥胖率（10.5%）高于农村（6.1%）,而按照腰围身高比划分则两者差别不大,城市、农村地区分别为17.9%和16.1%。在调整了年龄、性别、受教育程度、城乡等因素后,正常体重人群中心型肥胖者心脑血管疾病危险因素聚集的比例是非中心型肥胖者的2.272倍。结论体重正常人群中约有17%为中心型肥胖,并伴有心脑血管疾病危险因素聚集的风险升高。建议在开展肥胖干预时,不仅要强调维持健康体重和腰围,更要结合腰围身高比指标,倡导通过控制饮食和增加身体活动来控制肥胖。     

基于ANSYS的港口起重机桁架结构的优化设计

随着航运的发展,港口起重机也迅速发展。目前,不仅要求起重机有更高的起重量和起升高度,还要求起重机的重量轻、作业空间大。为了减轻自重、简化设计方法,应用ANSYS优化模块提供的一阶优化方法对起重机桁架结构优化,优化后起重机自重减小23.2%,质量明显减小。     

水中重法测试粗骨料表干质量的新试验方法研究

在现行规范网篮法测试粗骨料密度方法的基础上,进行了粗骨料浸水24h前后的受力状态分析,以骨料浸水24h前后的水中质量差计算骨料的吸水量,由此计算骨料的表干质量。新试验方法在研究过程中,进行了试验的过程设计并进行了大量试验验证,并且与现有试验方法进行了测试数据的对比分析,发现该方法科学合理,测试的数据准确稳定。     

超高分子量聚乙烯高温环境抗冲击能力研究

为研究超高分子量聚乙烯纤维(UHMWPE)在高温环境下的热性能和力学特性,对不同高温处理1h后的UHMWPE进行了SEM、DSC以及XRD分析。结果表明:150℃处理后纤维表面和断面已失去原有结构,XRD衍射峰峰值明显降低;DSC结果显示,与高温试验前及其它高温处理后有2个较大的吸热峰不同,150℃处理的样品仅有1个吸热峰,且峰值较低。对纤维包覆成的CDF进行爆轰性能试验,结果表明150℃处理后的样品抗冲击强度严重下降,已不能满足CDF的要求。     

BDS/GPS短基线的抗差方差分量估计及其应用

BDS/GPS组合观测值受观测环境的影响难免存在粗差或多路径等误差,基于最小二乘的方差分量估计不具有抵抗粗差或多路径等误差的能力,严重影响了随机模型的有效性。针对这一问题,基于抗差估计思想,引入双因子等价权函数,给出了抗差方差分量估计的实现过程。通过对BDS/GPS短基线实测数据进行分析和计算,表明抗差方差分量估计可有效抵抗粗差或多路径等误差,提高了随机模型的可靠性,抗差估计成果具有更高的内符合精度。