大跨度拱桥减震分析

以西藏尼木大桥为研究对象,结合该桥型特点,采用大型通用软件对其进行了模态分析和动力计算.通过模拟地震响应得到该桥的反应特性,由此采用调谐质量控制器(TMD)对该桥进行受控分析.采用振型贡献率确定受控模态,在获取TMD系统的优化参数后将其模拟入有限元模型中,并最终通过时程分析验证了TMD运用于拱桥被动减震控制的有效性.     

煤合成柴油(F-T柴油)在柴油机上的试验研究

试验研究了单缸柴油机燃用F-T柴油和0号柴油的燃烧特性和排放特性。与发动机燃用0号柴油相比，燃用F-T柴油时燃油消耗率降低，有效热效率升高，有害排放降低，结果表明，F—T柴油是一种高品质的柴油机代用燃料。     

互通式立交匝道线形组合的检验

通过速度图检验互通式立交匝道线形组合是否恰当,对匝道线形组合进行优化调整,使立交线形设计更加合理,符合汽车在立交区短时间内加速和减速的变化,保证行车安全。     

浅谈钢筋焊接及施工

为了方便钢筋作业施工,特做出如下作业指导以为借鉴。     

Tool Wear Prediction in Micro-end-milling with Hard Material

The applications of micro-machining have increased drastically in the last ten years. However, tools with less than 1mm diameter using for micro-mills have very short and unpredictable life when they are used to cut hard metals. In this study, preliminary design of experiment (DOE) test program was conducted to investigate and identify the factors affecting tool wear at the micro-scale with hard material. Analysis of variance (ANOVA) and Taguchi method were efficient to determine appropriate cutting condition and the effect of parameters. A simple model was also developed to predict the width of slots on the workpiece along the cutting length. The obtained results can provide the basic guidelines for parameter setting of micro-end-milling with hard material.     

在役轨道交通矮塔斜拉桥检测与评估

以某在役轨道交通矮塔斜拉桥的检测与评估为例,通过对矮塔斜拉桥受力特点的分析,确定了定期检测中矮塔斜拉桥的检测重点.主梁、主塔和墩柱的恒载几何形态测量表明,该矮塔斜拉桥整体保持稳定的状态,主梁跨中有沉降的趋势;通过桥梁自振特性、斜拉索索力和动位移的测试,明确了该桥的动力特性和动力响应;通过外观检查,明确了主梁主塔混凝土结...     

玄武岩纤维（BFRP）筋与混凝土粘结性能试验研究

玄武岩纤维筋是一种新型的复合材料,具有强度高、耐腐蚀等特点,用它代替混凝土路面结构中的钢筋,可解决因雨水进入引起的连续配筋混凝土路面钢筋锈蚀问题。玄武岩纤维筋与混凝土的粘结性能,是影响其推广应用的关键技术之一。本文运用18个中心拉拔试件研究了不同螺纹表面玄武岩纤维筋与混凝土之间的粘结性能,试验结果表明：玄武岩纤维筋与混凝土试验粘结强度在11.592～23.578MPa之间,粘结强度随着玄武岩纤维筋表面螺纹深度与螺纹间距的变化而变化;有螺纹玄武岩纤维筋的粘结强度明显高于无螺纹玄武岩纤维筋,玄武岩纤维筋最佳螺纹间距约为筋直径长度的80%,最佳螺纹深度约为直径长度的10%;拉拔试件的破坏形态均为玄武岩纤维筋与混凝土接触面混凝土的剪切破坏而拔出。     

Effects of erigeron breviscapus （Vant.） Hand-Mazz pretreatment on pathology and oxyradical level following spinal cord ischemia-reperfusion injury in rabbits

Objective To investigate the effects of erigeron breviscapus (Vant.) Hand-Mazz (erigeron breviscapus) pretreatment on pathology and oxyradical level in the spinal cord after ischemia-reperfusion (I/R) injury in rabbits. Methods A total of 40 New Zealand white rabbits were randomly divided into three groups: sham-operation group with 10 rabbits treated with only abdominal aorta exposure without occlusion, control group with 15 rabbits that underwent ischemia for 50 minutes and treated with matched saline, and experimental group with 15 rabbits that underwent ischemia for 50 minutes and treated with erigeron breviscapus (9mg/kg) injection before ischemia. Malondialdehyde (MDA) level and superoxide dismutase (SOD) activity in the spinal cord were examined at 6 and 24 hours after I/R, respectively. The morphological changes and the number of the spinal cord anterior horn motor neurons were observed and counted under the light microscope and electron microscope, respectively. Results The level of MDA was markedly decreased and SOD activity was increased in the experimental group compared with those in the control group (P<0.01). Compared with that in the control group, the number of motor neurons in the experimental group significantly increased at 24h after I/R (P<0.01) and the morphous of the motor neurons improved. Conclusion Erigeron breviscapus can reduce oxyradical production and the apoptosis of nerve cells, and protect nerve tissue structure and function after spinal cord I/R.     

服务世博会的新能源车

走在上海世博会园区内,你不仅能欣赏到风格各异、造型独特的展馆,还会看到各类新能源汽车在往来运行。为世博会提供交通服务的1000多辆新能源汽车各具特色,不仅为上海世博会增添了一道靓丽的风景线,也是构成“低碳世博”的重要组成部分,并展示了我国新能源汽车的技术成果。     

选择性COX-2抑制剂Celecoxib预防大鼠术后腹腔粘连的实验研究

目的 探讨Celecoxib对大鼠术后腹腔粘连形成的预防效果及其机制.方法 80只SD大鼠随机分为5组:接受腹膜擦损术为A组,接受腹膜擦损术+40mg/(kg·d)Celecoxib为B组,接受腹膜擦损术+20mg/(kg·d)Celecoxib为C组,接受腹膜擦损术+透明质酸钠凝胶为H组,仅接受开、关腹操作的假手术为S组.各组随机半数大鼠于术后第8天和15天处死,肉眼评估大鼠一般情况和腹腔粘连程度,免疫组化法检测粘连组织VEGF和CD34.结果 5组大鼠术后粘连程度组间差别具有显著性意义(P<0.01),B组、C组的粘连评分均明显小于H组、A组.VEGF蛋白表达量A组最强,次之分别为H组、C组、B组,S组最弱.CD_(34)表达量A组最强,次之分别为H组、C组、B组,S组最弱.结论 术后短期口服Celecoxib可有效预防大鼠术后腹腔粘连形成,效果优于透明质酸钠凝胶.机制可能与抑制COX-2活性后下调VEGF表达,抑制粘连组织新生血管发生有关.