板梁桥在特种车辆荷载作用下的结构检测与评估

通过对桥梁在特种车辆荷载作用下的结构响应监测和理论计算分析,发现特载对该板梁桥造成的主要损害是削弱了板梁间的联结强度。最后按照相关规范对该桥在经历特种荷载后的技术状况进行了评定。     

政府工程采购的发展情况及存在问题

政府采购机制是规范化我国政府投资建设项目管理的一个重要工作领域。文章针对我国政府采购和政府工程采购的基本发展情况进行了说明,并对政府工程采购发展过程中存在的主要问题进行了分析。     

混凝土桥梁的温度作用分析和设计

对梯度温度应力的分解分析及对一典型的预应力混凝土连续刚构箱梁桥应力计算比较后,得出梯度温度作用特性及在桥梁结构设计的一些经验.     

降低节能车燃油消耗量的研究(2)

（上接2008年第10期） 化油器的浮子工作高度是否合理,对化油器能否正常工作影响很大,浮子工作高度过高或过低,会造成化油器油平面过低或过高,可燃混合气过浓或过稀,发动机出现动力不足、耗油量偏高等现象。调整浮子高度,尽可能降低浮子工作高度,使化油器提供适度的稀混合气,在不影响动力性或少量降低功率输出的情况下,可达到降低发动机油耗的目的。     

FOLLICULO-STELLATE CELLS OFTHE RAT ANTERIOR PITUITARY RESPONDED TO ANGIOTENSIN Ⅱ BY INCREASING INTRACELLULAR CONCENTRATION

Objective The main purpose of this study was to investigate whether the folliculo-stellate cells (FSC) respond to angiotensin(Ang) Ⅱ by increasing intracellular free concentration ([]i) ,and where the o-rigin of mobilization is if that has occurred. Methods Pituitary cells in primary culture were prepared from male Wister rats(250g) by a conventional method and cultured in MEM supplemented with 4％ normal rat serum. Af-ter 2 days in culutre,cells were loaded with 1 μmol/L fura-PE3/AM for 1 h and subjected to a ment with Quanti Cell 700 system. Excitation wavelengths of 340 and 380 nm were selected by means of a computer-controlled filterwheel. Results The of FSC in the rat anterior pituitary was elevated by Ang Ⅱ. The eleva-tion of of FSC induced by 0. 1,1.0,10 and 100 nmol/L Ang Ⅱ was (56.33±6.18), (117.07± 36.07), (175.59 ± 40.01 ) and (216.02 ±11.52) nmol/L, respectively. The increase of of FSC induced by 100nmol/L Ang Ⅱ was not influenced by the medium without (0Ca),but significantly suppressed by thapsigargin (TG),an inhibitor of ATPase. The rate of responsive FSC to Ang Ⅱ (100 nmol/L) was 61.84％ which was obviously higher than that of pituitary endocrine cells (43.49％). Conclusion The present experiment demonstrates that the FSC in the rat anterior pituitary responds to Ang Ⅱ by increasing [which raises the possibility that Ang Ⅱ re-leased from either lactotrophs or gonadotrophs affects FSC through paracrine mechanism. The elevation of [induced by Ang Ⅱ presents a dosage-dependent relation, and is possibly because of the release of from an intra-cellular pool (s). Fashions of release are relative to the concentration of Ang Ⅱ. The results indicate that Ang Ⅱ functions as a paracrine factor among pituitary cells including FSC.     

考虑桩土变形协调的复合地基变形计算模型的初步研究

本文针对当前求解刚性基础下复合地基沉降变形时较少考虑桩土间变形协调的情况,对若干试验结果进行了分析,并对复合地基的单桩侧摩阻力分布形状作了一定的假定,简化计算,然后联合荷载传递法,Mindlin解答和弹性力学解答得到了单桩模型中桩体和桩间土的变形计算模型。     

系泊系统的时域仿真及其非线性动力学特性分析

应用时域仿真的方法研究了系泊系统的非线性动力学特性。以三阶操纵运动方程为基础,引入定常的风力、潮流作用力和二阶波浪力,建立了系泊系统三自由度的运动微分方程。在此数学模型的基础上,建立了系泊系统的多自由度的计算机仿真模型。在风浪流联合作用的情形下,对一艘单点系泊油轮的动力学行为进行了仿真研究。以潮流速度和系缆程度为分岔控制参数,在参数平面上给出了局部分岔集。研究表明,系泊系统的动力学行为具有强烈的非线性特征。在仿真过程中观察到了吸引子的共存和Hopf分岔。局部分岔集将参数平面分为3个系统动力学行为本质不同的区域。极值系泊力水平与系泊系统的动力学行为有着密切的关系。对于单点系泊船舶而言,顶风顶浪顶流的状态并不一定是最为危险的工况。局部分岔集的确定为系泊系统参数的选择提供了决策依据。     

浅谈兰州市北环路东段黄土边坡的防护与排水设计

以兰州北环路工程为背景,介绍了黄土高边坡的防护及排水设计,有关经验可供相关专业人员参考。     

汽车车身缝隙的电磁屏蔽特性仿真研究

汽车车身缝隙是汽车电磁于扰的重要耦合途径.通过分析汽车车身缝隙的结构,提出车身缝隙的简化模型,进而建立其仿真计算模型;分别改变车身缝隙模型的相关结构参数,考察相应的电磁场屏蔽效能的变化.仿真结果表明,车身缝隙越长,屏蔽效能越低,电磁干扰越容易耦合进车内;车身缝隙越窄,电磁屏蔽效能越高;改变车身缝隙搭接部分的长度和拐角角度并不能保证提高其屏蔽效能,具体变化趋势与频率范围有关.     

基于路网的道路建设项目经济评价中效益计算方法研究

效益计算是进行道路建设项目经济评价的一个重要内容,效益计算一般涉及正常交通量、转移交通量和诱增交通量.通过分析给出了确定道路建设项目影响区分析方法,并在分析各种类型交通量对道路建设项目效益影响的基础上,给出了基于路网的道路建设项目效益计算模型,为更加合理进行经济评价提供参考.