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221.
目的利用基因工程方法克隆SD大鼠Atoh1 cDNA编码序列并测定分析其克隆序列。方法采用非对称互补引物/模板法,制备Atoh1 cDNA的编码序列,将其克隆入PMD-19T载体中并测序。结果经酶切鉴定、测序分析表明,扩增得到的大鼠Atoh1基因CDS区全长为1 056 bp,编码351个氨基酸;测定序列与GenBank中公布的参考序列对比,有2处碱基发生突变,但克隆序列编码的氨基酸序列与参考序列完全一致。这两处碱基应为单核苷酸多态性(SNP)位点,突变为无义突变,不影响蛋白的表达。结论成功克隆了Atoh1 cDNA编码序列,为进一步对感音神经性耳聋的基因治疗奠定了基础。 相似文献
222.
介绍了美军几种常用的轮式和履带式装备铁路制式加固器材--轮挡、拉牵绳的种类、结构组成、使用方法以及在运输工具上采取的技术措施.为研究分析美军铁路运输加固器材奠定了基础,也为我军铁路制式加固器材的研发和应用提供了参考. 相似文献
223.
为了研究桩承式路堤中填土的破坏模式,采用有限元方法对不同桩间距、填土高度和摩擦角进行了参数敏感性分析.根据计算得到的屈服区和增量等效塑性应变结果,分析了不同情况下填土的破坏机理.结果显示:对于填土高度与桩间距之比H/s≤1的低路堤,填土中的破坏面为通过桩边缘的竖直面;对于H/s≥1.2的高路堤的情况,最终填土中将发展出... 相似文献
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225.
Bundled hybrid offset riser (BHOR) global strength analysis, which is more complex than single line offset riser global strength analysis, was carried out in this paper. At first, the equivalent theory is used to deal with BHOR, and then its global strength in manifold cases was analyzed, along with the use of a three-dimensional nonlinear time domain finite element program. So the max bending stress, max circumferential stress, and max axial stress in the BHOR bundle main section (BMS) were obtained, and the values of these three stresses in each riser were obtained through the "stress distribution method". Finally, the Max Von Mises stress in each riser was given and a check was made whether or not they met the demand. This paper provides a reference for strength analysis of the bundled hybrid offset riser and some other bundled pipelines. 相似文献
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228.
S. O. Kang S. O. Jun H. I. Park K. S. Song J. D. Kee K. H. Kim D. H. Lee 《International Journal of Automotive Technology》2012,13(4):583-592
This research aims to develop an actively translating rear diffuser device to reduce the aerodynamic drag experienced by passenger cars. One of the features of the device is that it is ordinarily hidden under the rear bumper but slips out backward only under high-speed driving conditions. In this study, a movable arc-shaped semi-diffuser device, round in form, is designed to maintain the streamlined automobile??s rear underbody configuration. The device is installed in the rear bumper section of a passenger car. Seven types of rear diffuser devices whose positions and protrusive lengths and widths are different (with the basic shape being identical) were installed, and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. The main purpose of this study is to explain the aerodynamic drag reduction mechanism of a passenger car cruising at high speed via an actively translating rear diffuser device. The base pressure of the passenger car is increased by deploying the rear diffuser device, which then prevents the low-pressure air coming through the underbody from directly soaring up to the rear surface of the trunk. At the same time, the device generates a diffusing process that lowers the velocity but raises the pressure of the underbody flow, bringing about aerodynamic drag reduction. Finally, the automobile??s aerodynamic drag is reduced by an average of more than 4%, which helps to improve the constant speed fuel efficiency by approximately 2% at a range of driving speeds exceeding 70 km/h. 相似文献
229.
H.?-Z.?Li L.?LiEmail author L.?He M.?-X.?Kang J.?Song L.?-Y.?Yu C.?Wu 《International Journal of Automotive Technology》2012,13(3):441-450
A Traction Control System (TCS) is used to control the driving force of an engine to prevent excessive slip when a vehicle
starts suddenly or accelerates. The torque control strategy determines the driving performance of the vehicle under various
drive-slip conditions. This paper presents a new torque control method for various drive-slip conditions involving abrupt
changes in the road friction. This method is based on a PID plus fuzzy logic controller for driving torque regulation, which
consists of a PID controller and a fuzzy logic controller. The PID controller is the fundamental component that calculates
the elementary torque for traction control. In addition, the fuzzy logic controller is the compensating component that compensates
for the abrupt change in the road friction. The simulation results and the experimental vehicle tests have validated that
the proposed controller is effective and robust. Compared with conventional PID controllers, the driving performance under
the proposed controller is greatly improved. 相似文献
230.
In this study, a control strategy for a dual mode power split-type hybrid electric vehicle (HEV) is developed based on the powertrain efficiency. To evaluate the transmission characteristics of the dual mode power split transmission (PST), a mechanical loss model of the transmission (TM loss) is constructed. The transmission efficiency, including the TM loss, is evaluated for the dual mode PST. Two control strategies for the dual mode PST are proposed. An optimal operation line (OOL) control strategy is developed to maintain a high engine thermal efficiency by controlling the engine operation point on the OOL. A speed ratio (SR) control strategy is proposed to obtain a greater transmission efficiency by shifting the engine operation point when the dual mode PST operates near the mechanical points. Using the TM loss and the proposed control strategies, a vehicle performance simulation is conducted to evaluate the performance of the two control strategies for dual mode PST. The simulation results demonstrate that, for the SR control strategy, the engine efficiency decreases because the engine operates beyond the OOL. However, the transmission efficiency of the dual mode PST increases because the PST operates near the mechanical point where the PST shows the greatest transmission efficiency. Consequently, the fuel economy of the SR control strategy is improved by 3.8% compared with the OOL control strategy. 相似文献