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排序方式: 共有1398条查询结果,搜索用时 31 毫秒
151.
计及管道边界条件滑移的影响,研究微极流体蠕动泵,经由圆柱形管道输运的Stokes流动.壁面运动的控制方程为正弦波方程.使用润滑理论,得到了轴向速度、微转动向量、流函数、压力梯度、摩擦力和机械效率的解析数值解.用图形表示出构成参数,如像耦合参数、微极参数和表征蠕流泵特性的滑移参数、摩擦力和俘获现象的影响.数值计算表明,当耦合参数较大时,需要蠕动泵的压力更大,而微极参数和滑移参数正相反.俘获团块的大小随耦合参数和微极参数的减小而缩小,而随滑移参数的增大而缩小. 相似文献
152.
Li Yin · Qin Qian · Lin Wang Huazhong University of Science Technology Wuhan China Hubei Key Laboratory for Engineering Structural Analysis Safety Assessment China 《Acta Mechanica Sinica》2011,27(3):445-451
We present a new analytical model for electrostatically actuated microbeams to explore the size effect by using the modified couple stress theory and the minimum total potential energy principle. A material length scale parameter is introduced to represent the size-dependent characteristics of microbeams. This model also accounts for the nonlinearities associated with the mid-plane stretching force and the electrostatical force. Numerical analysis for microbeams with clamped-clamped and cantilevered conditions has been performed. It is found that the intensity of size effect is closely associated with the thickness of the microbeam,and smaller beam thickness displays stronger size effect and hence yields smaller deffection and larger pull-in voltage. When the beam thickness is comparable to the material length scale parameter,the size effect is significant and the present theoretical model including the material length scale parameter is adequate for predicting the static behavior of microbeam-based MEMS. 相似文献
153.
Zheng Zhang · Xu Han · Chao Jiang State Key Laboratory of Advanced Design Manufacturing for Vehicle Body College of Mechanical Vehicle Engineering Hunan University Changsha China 《Acta Mechanica Sinica》2011,27(5):757-766
In this article,an effective technique is developed to efficiently obtain the output responses of parameterized structural dynamic problems.This technique is based on the conception of reduced basis method and the usage of linear interpolation principle.The original problem is projected onto the reduced basis space by linear interpolation projection,and subsequently an associated interpolation matrix is generated.To ensure the largest nonsingularity,the interpolation matrix needs to go through a timenode choosing process,which is developed by applying the angle of vector spaces.As a part of this technique,error estimation is recommended for achieving the computational error bound.To ensure the successful performance of this technique,the offline-online computational procedures are conducted in practical engineering.Two numerical examples demonstrate the accuracy and efficiency of the presented method. 相似文献
154.
Chun-Chuan Liu · Feng-Ming Li · Ting-Wei Liang · Wen-Hu Huang P.O.Box School of Astronautics Harbin Institute of Technology Harbin China 《Acta Mechanica Sinica》2011,27(5):785-795
In this paper,wave and vibratory power transmission in a finite L-shaped Mindlin plate with two simply supported opposite edges are investigated using the wave approach.The dynamic responses,active and reactive power flow in the finite plate are calculated by the Mindlin plate theory (MPT) and classic plate theory (CPT).To satisfy the boundary conditions and continuous conditions at the coupled junction of the finite L-shaped plate,the near-field and far-field waves are entirely contained in the wave approach.The in-plane longitudinal and shear waves are also considered.The results indicate that the vibratory power flow based on the MPT is different from that based on the CPT not only at high frequencies but also at low and medium frequencies.The influence of the plate thickness on the vibrational power flow is investigated.From the results it is seen that the shear and rotary inertia correction of the MPT can influence the active and reactive power at the junction of the L-shaped plate not only at high frequencies but also at low and medium frequencies.Furthermore,the effects of structural damping on the active and reactive power flow at the junction are also analyzed. 相似文献
155.
Cheng-Kang Wu · Hai-Xing Wang · Xian Meng · Xi Chen · Wen-Xia PanInstitute of Mechanics Chinese Academy of Sciences Beijing China School of Astronautics Beijing University of Aeronautics Astronautics Beijing China Department of Engineering Mechanics Tsinghua University Beijing China 《Acta Mechanica Sinica》2011,27(2):152-163
The aerodynamic aspects of indirect thrust measurement by the impulse method have been studied both experimentally and numerically. The underlying basic aerodynamic principle is outlined, the phenomena in subsonic, supersonic and arc-heated jets are explored, and factors affecting the accuracy of the method are studied and discussed. Results show that the impulse method is reliable for indirect thrust measurement if certain basic requirements are met, and a simple guideline for its proper application is given. 相似文献
156.
Long-He Xu · Zhong-Xian Li · Jia-Ru Qian School of Civil Engineering Beijing Jiaotong University Beijing China School of Civil Engineering Tianjin University Tianjin China Department of Civil Engineering Tsinghua University Beijing China 《Acta Mechanica Sinica》2011,27(3):399-405
A two-stage damage detection approach is proposed and experimentally demonstrated on a complicated spatial model structure with a limited number of measurements. In the experiment,five known damage patterns,including 3 brace damage cases and 2 joint damage cases,were simulated by removing braces and weakening beam-column connections in the structure. The limited acceleration response data generated by hammer impact were used for system identification,and modal parameters were extracted by using the eigensystem realization algorithm. In the first stage,the possible damaged locations are determined by using the damage index and the characteristics of the analytical model itself,and the extent of damage for those substructures identified at stage I is estimated in the second stage by using a second-order eigen-sensitivity approximation method. The main contribution of this paper is to test the two-stage method by using the real dynamic data of a complicated spatial model structure with limited sensors. The analysis results indicate that the two-stage approach is ableto detect the location of both damage cases,only the severity of brace damage cases can be assessed,and the reasonable analytical model is critical for successful damage detection. 相似文献
157.
对具有分布时滞的递归神经网络模型进行了研究,并通过构造适当的Lyapunov-Krasovskii函数和非线性控制函数,采用不等式估计方法,得到了所研究模型一般衰减同步的充分条件.最后给出了一个例子,进一步说明了所得结论的正确性. 相似文献
158.
治疗胆石症蒙药苏斯-12中多种元素的ICP-AES法测定及分析 总被引:3,自引:0,他引:3
通过分析治疗胆囊炎、胆石症的蒙药苏斯—12中微量元素含量,探讨蒙药苏斯—12的药效与微量元素含量的关系。应用高压密封微波消解、电感耦合等离子体原子发射光谱法(ICP-AES)对蒙药苏斯—12进行微量元素含量分析。在蒙药的配制及整体研究工作中发现它们含有多种氨基酸和丰富的微量元素,实验结果表明:苏斯—12中含有丰富的微量元素,尤其Ca,Al,Mg,Fe,Sr,Mn,Zn,Cu等元素的含量比较高,而Pb,Cd,As等元素含量相对低,都低于国家限定值。加标回收率在94.63%~106.40% 之间,相对标准偏差RSD≤3.35 %,检出限在≤0.009 μg·L-1。蒙药苏斯—12有效控制和治疗胆囊炎、胆石症,总有效率达91.2%和100%,蒙药苏斯—12中的微量元素与药效之间有密切的关系。 相似文献
159.
160.
分析了化学反应,对流过半无限竖直多孔板的、粘性耗散的、非定常的磁流体流动的影响.利用随时间变化的相似参数,将运动、能量、溶质的控制方程变换为常微分方程,并用有限单元法数值地求解所得到的常微分方程.用图形给出了不同参数对速度、温度和浓度分布的影响,用表格给出了不同物理参数值时,表面摩擦力、Nusselt数和Sherwood数的数值. 相似文献