Analysis of a Passive Sequential Hydraulic Damper for Vehicle Suspension

Vibration isolation characteristics of a sequential hydraulic damper, employing external pressure relief valves, are investigated via analytical means. The sequential hydraulic damper is modelled as a nonlinear dynamical system incorporating nonlinearities due to orifice flows, gas spring and pressure relief mechanisms. The damping characteristics of the sequential hydraulic damper, are compared to those of a constant orifice and a semi-active sequential damper, and discussed in view of their vibration isolation performance. It is established that the performance characteristics of the sequential hydraulic damper are similar to that of a semi-active sequential damper. A tuning methodology to achieve appropriate control of the resonant peak and effective vibration isolation is proposed. The shock and vibration isolation performance of the vehicle model employing a sequential damper are evaluated and compared to those of the vehicle model employing a constant orifice hydraulic damper. It is concluded that the vehicle ride performance can be improved considerably using an adequately tuned sequential damper.     

正确处理基础英语和专业英语教学的关系

本文对航海类院校英语教学过程中所暴露出来的问题，如重英语，轻专业；重基础英语，轻专业英语等现象进行了揭示，分析了出现这种现象的原因并且提出了避免问题的方案。     

人甲状腺C细胞免疫组织化学研究

应用抗降钙素抗体及ＡＢＣ免疫酶技术，对５０例（其中儿童３３例，成人１７例）尸体解剖甲状腺标本（非内分泌及甲状腺疾病）研究发现：Ｃ细胞主要集中在甲状腺两侧叶的深部，降钙素免疫反应阳性细胞呈多角形或类圆形，胞浆较丰富，阳性反应产物弥漫分布在胞浆中，阳性细胞位于滤泡细胞间或滤泡旁；或散在分布，或小灶状聚集，或成串排列。儿童甲状腺Ｃ细胞含量较成人为高，尤以婴儿为著，随着年龄增长，甲状腺Ｃ细胞含量呈逐渐减少趋势。     

PVTxSTUDYOFBINARYSYSTEMR22／R152aWITHBURNETTMETHOD

ＰＶＴｘＳＴＵＤＹＯＦＢＩＮＡＲＹＳＹＳＴＥＭＲ２２／Ｒ１５２ａＷＩＴＨＢＵＲＮＥＴＴＭＥＴＨＯＤＳｕＺｈｉｊｕｎＪｉａｎｇＢａｏｃｈｅｎｇＹａｎＪｉａｌｕ（ＳｈａｎｇｈａｉＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ）（ＨａｒｂｉｎＩｎｓｔｉｔｕｔｅｏｆＴ...     

母亲因素与低出生体重儿的关系

对1986年10月～1987年9月及1989年1月～1989年12月期间出生的365例低出生体重儿,按其母亲情况作回顾调查和分析。低体重儿发生率为7.99%,死亡率15.07%。母亲主要疾病为妊娠高血压综合征和中、重度贫血,经X~2检验均有显著意义。多元逐步回归分析表明母亲为农民、早产、新生儿畸形为最危险因素。文章认为加强围产期保健是降低低体重儿发生的有效措施。     

桶式基础结构土压力分布规律

桶式基础结构是一种轻型结构,适用于承载力低的淤泥质地基,其稳定计算依靠桶体与土共同作用抵抗外荷载,因此土压力是桶式基础结构稳定计算的核心内容,其分布规律和大小对计算结果起到控制作用。通过模型试验结果验证了有限元模型参数取值的合理性,从而采用有限元数值模拟的方法,探讨了波浪荷载和回填荷载作用下,不同土层产生的主被动土压力分布规律,得到位移形式对土压力大小的影响、不同土层之间相互作用引起土压力分布形态的变化、理论公式的修正系数以及施工顺序对土压力分布形态的影响。研究成果明确了不同荷载作用和土层分布对土压力的影响规律,修正了主被动土压力的传统计算公式,为桶式基础结构稳定计算奠定了一定的基础。     

电动助力转向系统电机补偿控制研究

在现代助力转向系统中,电动助力转向系统越来越普及开来,为了提高电动助力转向系统的系统动态性能,同时驾驶员也能获得良好的操纵手感,需要具有惯量小、阻尼小和摩擦小等特点的电机。但是由于技术的限制,电机的惯量、阻尼和摩擦不可能无限度的降低。我们就电机惯量补偿控制、电机阻尼补偿控制和电机摩擦补偿控制等三种控制形式进行了研究。     

六冲河特大桥荷载试验分析研究

以六冲河特大桥为工程背景,对斜拉桥成桥状态下的桥面线形和斜拉索索力进行了测试.同时使用MADIS软件建立空间有限元模型,通过对桥梁结构活载作用效应进行分析,确定了静载试验的最不利工况,以及各工况加载载位.经现场静动载试验,得出了各加载工况下相应的挠度、应变、索力和塔偏参数,并对桥梁承载能力进行了评定.     

客运专线预制箱梁后浇翼缘板施工技术

由于受隧道施工限界影响,客运专线双线整孔预制箱梁无法通过隧道,预制时先切除两侧部分翼缘板,待架设后再现浇切除部分翼缘板。介绍了切除翼缘板箱梁现浇施工支架的设计和关键施工技术,可为同类预制梁施工提供技术参考。     

Model and simulation of a new ultra-narrow trigger frequency alterable pulse generator

Two new kinds of ultra-narrow trigger frequency alterable picosecond pulse generator are presented. One can produce positive pulses and the other can produce negative pulses. The two pulse generators are subdivided into three parts: signal driving circuit, differentiator network and pulse shaping circuit. The pulse shaping circuit is made of step recovery diode (SRD) and short-circuit microstrip line. A positive pulse with width of 54 ps (50%–50%), rising time of 30 ps (10%–90%) and falling time of 32 ps (90%–10%), and a negative pulse with width of 54 ps (50%–50%), rising time of 30 ps (90%–10%) and falling time of 30 ps (10%–90%) are achieved in simulation. All of the components are ready-made and inexpensive. They can be applied in ultra-wideband (UWB) communication system, such as transmitters and receivers.