新型纳米吸波材料研究现状与进展

介绍了纳米微波吸收材料的吸波机理及其优异的吸波性能。综述了纳米材料(纳米铁氧体及其复合物、纳米金属、纳米陶瓷、纳米导电聚合物)作为吸波介质的特点和应用背景,提出了高性能纳米微波吸收剂的发展方向。     

减振器冲击性能测试方法研究

根据舰船所受到的冲击力学过程,对减振器冲击性能测试问题进行了分析,提出了基于气缸式冲击模拟台的减振器冲击性能测试方法,并介绍了试验测量系统.采用该方法对钢丝绳减振器作为冲击防护元件时的力学特性进行了研究,得出了该元件关于压缩/拉伸非对称的冲击耗能特性,并分析了参数变化特点.     

船用柴油发电机组的浮筏隔振及其效果分析

为了减小船用机械振动向船体结构的传递,常采用浮筏隔振系统对船舶设备进行集中隔振。文章对某船用柴油发电机组进行了隔振设计并研究其效果,采用有限元软件MSC Patran建立了隔振系统的动力学模型。首先计算得到了各阶模态,然后分析了隔振系统参数变化对隔振效果的影响,最后研究了不同激励对瞬态动力学特性的影响。计算结果表明,浮筏隔振系统的设计满足隔振要求,隔振性能及抗冲击性能良好。     

浅埋暗挖车站施工技术

在重庆西部国际会展中心配套施工交通工程高义口车站施工中:施工通道进入车站主体转换施工采用混凝土与工字钢门架相结合的方式;车站主体开挖施工采用周边钻设减震孔的方式进行减震施工;2号风道与车站主体交叉口段施工开挖采用静态爆破方式施工,衬砌采用先交叉口门柱后车站主体衬砌的方式进行。通过以上施工技术顺利实现了复杂环境下浅埋暗挖隧道施工。     

变流器柜体冲击和随机振动试验的数值模拟

根据标准GB/T 21563-2008《轨道交通机车车辆设备冲击和振动试验》,采用ANSYS有限元分析软件计算了随机振动环境下的响应,得到了结构的1σ、2σ、3σVonMises最大应力.利用材料的S-N曲线,并根据Steinberg提出结构在随机载荷作用下的响应是基于高斯分布和Miner提出的线性疲劳累计损伤理论,对设计的结构在给定随机振动环境下的疲劳寿命进行了预估.运用瞬态动力学分析方法模拟了冲击试验过程中的受力情况.     

机车车辆设备振动冲击试验系统的技术研究

阐述了机车车辆设备力学环境试验要求,给出了机车车辆设备振动冲击试验系统的技术条件,分析了实现技术条件所面临的技术难点,提出了试验系统的解决方案.基于该方案而研制的大型振动冲击试验系统通过了计量检定与试验验证,各项技术指标均达到或超过设计要求,满足机车车辆设备系统级产品的试验要求.     

Optimal Burn-in and Preventive Maintenance Modeling with Competing Failure Processes

In this article, we assume that the product in the burn-in procedure only experiences continuous smooth degradation process, while in the field operation period the product experiences both continuous smooth degradation process and shock process. The shock process can cause the product not only traumatic failure,but also additional abrupt degradation damage. After the system reliability model and maintenance model have been proposed, the optimal burn-in setting and age replacement duration are obtained under the considering of minimizing the long run average cost rate. A numerical example with the real data is analyzed to illustrate the application of the model.     

丰田A540E型自动变速器换挡冲击的故障诊断与排除

针对某款丰田凌志轿车出现升挡冲击的一例故障现象,经分析认为是其装备的A540E型自动变速器阀体发生故障所导致。从基本检查、时滞试验、主油压检测、动力传动分析、电液系统分析、手动挡试验,直至自动变速器拆检,最终确定故障是2挡制动器单向节流阀在维修时漏装所致。     

全脑缺血再灌注损伤后JUN蛋白在大鼠海马的表达及热休克预处理对其表达的影响

目的研究全脑缺血再灌注损伤后JUN蛋白在大鼠海马的表达及热休克预处理对其表达的影响。方法以四血管法建立全脑缺血再灌注模型。将大鼠置于42℃中15 min行热休克预处理,全脑缺血6 min后行2 h、6 h、12 h、24 h3、d、5 d再灌注后处死,取海马脑组织行HE染色、JUN蛋白免疫组化染色,TUNEL法检测凋亡细胞。结果缺血再灌注后2 h JUN蛋白在CA1区开始表达,6 h达到高峰,5 d时仍有表达;CA3区JUN蛋白的表达弱于CA1区(P<0.05);同时CA1区细胞损伤明显。热休克预处理组JUN蛋白表达在CA1和CA3区相应时点减弱(P<0.05),细胞损伤轻微,凋亡细胞减少(P<0.05)。结论全脑缺血再灌注损伤后JUN蛋白过度表达参与了神经元损伤过程,热休克预处理通过下调JUN蛋白过度表达具有脑保护作用。     

Real-time queue length estimation using event-based advance detector data

Real-time queue length information at signalized intersections is useful for both performance evaluation and signal optimization. Previous studies have successfully examined the use of high-resolution event-based data to estimate real-time queue lengths. Based on the identification of critical breakpoints, real-time queue lengths can be estimated by applying the commonly used shockwave model. Although breakpoints can be accurately identified using lane-by-lane detection, few studies have investigated queue length estimation using single-channel detection, which is a common detection scheme for actuated signal control. In this study, a breakpoint misidentification checking process and two input-output models (upstream-based and local-based) are proposed to address the overestimation and short queue length estimation problems of breakpoint-based models. These procedures are integrated with a typical breakpoint-based model framework and queue-over-detector identification process. The proposed framework was evaluated using field-collected event-based data along Speedway Boulevard in Tucson, Arizona. Significant improvements in maximum queue length estimates were achieved using the proposed method compared to the breakpoint-based model, with mean absolute errors of 35.7 and 105.6 ft., respectively.