聚氨酯-钢板夹层结构正交异性桥面板力学性能分析

建立聚氨酯-钢板夹层结构正交异性桥面板及普通钢结构正交异性桥面板空间有限元模型,比较两种正交异性桥面板在不同受力状况和不同截面处各控制点的应力状态,分析两种桥面板的受力性能差异.结果表明:对于前一种桥面板跨中截面和支点截面最大弯矩时,截面上的各控制点的应力随纵向加劲肋数量的减少影响不大,而后一种桥面板的各应力则影响很大.跨中截面处,随纵向加劲肋数量的减少,前一种桥面板的挠度及纵向加劲肋底面的横桥向应力变化不大,后一种桥面板的相应值则影响很大,纵桥向应力则都随之增大.支点截面处,随纵向加劲肋数量的减少,两种桥面板的挠度及纵向加劲肋底面的横桥向应力变化不大,且其差值很小,而纵桥向应力则都随之增大,且其差值很大.聚氨酯芯层的应力只有几兆帕.采用聚氨酯-钢板夹层结构正交异性板代替普通正交异性钢桥面板可大幅度减少纵向加劲肋的数量,甚至在板的纵、横向支承间距适当时可取消纵向加劲肋.     

Rapid analysis of components in Rhizoma Anemarrhenae by HPLC-DAD-MS and HPLC-DAD-TOFMS

A global quality control method based on high performance liquid chromatography (HPLC) coupled with diode array detection (DAD), single quadrupole mass spectrometry (MS) and time-of-flight mass spectrometry (TOFMS) was developed for simultaneous determination of seven major components (mangiferin, neomangiferin, timosaponin E1, timosaponin E, timosaponin BⅡ, timosaponin BⅢ, and timosaponin AⅢ) and identification of most components in extracts of Rhizoma Anemarrhenae (RA). HPLC analysis was performed on an Agilent SB-C18 column (4.6 mm×150 mm, 5 μm) by gradient elution using acetonitrile and water-acetic acid(100∶0.05, v/v) as the mobile phase. Seven major components in RA were successfully separated. This quantitative method was fully validated in respect of the following performance criteria: linearity, precision, repeatability, stability, accuracy, limits of detection (LOD) and quantification (LOQ). A formula database of known compounds in RA was established, against which, most of the reported components in this herbal extract were identified effectively based on the extract masses acquired by TOFMS. This qualitative and quantitative method was successfully used to analyze the components in 10 batches of RA samples collected from different regions in China. This global quality control method, which consisted of HPLC-DAD-MS assay of seven major components and unambiguous identification of nineteen components, is suitable for routine quantification and comprehensive quality control of RA.     

Determination of enantiomeric impurity of etomidate by high performance liquid chromatography

Objective To determine enantiomeric impurity of etomidate using high performance liquid chromatography. Methods (R)-etomidate and (S)-etomidate were isopropanol-n-hexane. The flow rate of the mobile phase was 0.5mL/min. The detected wavelength was 242nm. Results (R)-etomidate and (S)-etomidate could be separated completely under these conditions. The precision of (R)-etomidate was 1.57% (n=3). The limit of detection of (R)-etomidate was 4.25ng/mL. The average percentage content of (S)-etomidate was 0.09% in the samples. Conclusion The method was repeatable and sufficiently sensitive to determine the enantiomeric impurity of etomidate. It allows the quantitation of the impurities at the 0.085% (w/w) level relative to etomidate at a concentration of the test solution of 5mg/mL.     

六四梁、八三墩拼组的异形架桥机在32m单线箱梁架设中的应用

郑西客运专线张家湾3号桥分左中右3幅,在架设左右幅单线箱梁时,采用的施工方案为利用已经架通的主线梁,在主线梁上整孔现浇32m单线箱梁,然后利用六四梁和八三墩组装一台垂直桥向的的异形架桥机,将整孔梁架设到位。实践证明,六四梁和八三墩拼组的异形架桥机造价低、适用性强,有效缩短了工期,适用于大跨度、高难度、地形环境差等高危险性桥梁架设工程。     

Bus journey times in medium size urban areas

The predictive accuracy of the models based on the fundamental relation between journey time and passenger demand can be improved through data disaggregation or route segmentation. Primary reason for this is the improvement in the estimates of stopping delays and delays due to passenger boarding and/or alighting (dwell time). Both Poisson and Negative Binomial model estimates of stoppings for passenger boarding and alighting are shown to improve with disaggregation. These improvements, however, contribute little to the overall predictability of the fundamental models which are useful for gaining insight into the significance and variability of the stopping delays and dwell time, or testing sensitivity to changes in the long term. Site or route specific models of journey times which have better predictive capability exist, and may be used for short-run planning. However, the interchangeability and performance over time of the latter, have to be evaluated before making definitive conclusions.     

单管高压旋喷桩在高速公路软基加固中的应用

高压旋喷法是利用喷射化学浆液与土混合搅拌来处理地基的一种方法.旋喷桩可以提高地基承载力,防止地基的不均匀沉降等.介绍高压旋喷桩在高速公路软基处理中的应用方法.     

N-取代芳基-N''''-(2,4-二氯苯氧乙酰基)氨基脲的合成与表征

以芳香取代酸为原料,用Curtius重排的方法合成异氰酸酯,直接与2,4-二氯苯氧乙酰肼作用,一锅法合成了4种N-取代芳基-N'-(2,4-二氯苯氧乙酰基)氨基脲类化合物.此法具有原料易得、操作简便、无需分离中间体等优点.目标产物的结构经元素分析、IR及1H NMR得到了确证.     

丙型肝炎病毒核心蛋白基因的克隆及表达

目的在大肠杆菌中表达丙型肝炎病毒(HCV)核心蛋白基因片段。方法以HCV全长cDNA质粒为模板进行PCR扩增,获得366bp的核心蛋白基因片段。将其插入连接载体pMD18-T vector中,酶切后再与表达载体pBV220连接,构建重组表达载体pBV220/HCV-C。经鉴定后温度诱导表达,采用SDS-PAGE电泳及Western-blot检测核心蛋白基因的蛋白表达。结果经温度诱导后获得目的基因的非融合表达,SDS-PAGE电泳显示在14000 u处有一表达条带;Western-blot结果显示其具有HCV抗原特异性。结论丙型肝炎病毒核心蛋白基因成功表达,对临床诊断试剂和HCV基因疫苗的研制有一定的意义。     

五轴转向重型汽车转向性能的研究

以多体系统动力学理论为基础,利用ADAMS建立了五轴转向重型汽车的整车虚拟样机模型,对该模型进行了仿真分析.由分析结果可知,转向轮转角越大,轮胎磨损越严重.为提高重型汽车的灵活性,延长轮胎的使用寿命,对该模型进行了优化.通过仿真分析可知,优化后的转向性能明显提高.同时分析比较了五轴转向重型汽车与前两轴转向重型汽车的转向性能,结果表明,五轴转向重型汽车转弯半径小,轮胎磨损小.     

改善全封闭水面舰艇舱室空气品质技术初探

改善舰艇舱室空气品质至关重要,目前国内没有合适的舰用空气净化设备,通过借鉴国外和我国民用空气净化设备及技术特点,探讨了有效改善全封闭水面舰艇舱内空气品质的途径.明确指出开发船用空气净化设备势在必行,对舱室内的空气进行消毒净化处理也是舰艇空调系统设计发展的必然趋势.