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991.
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
992.
Cementations formed in geological timescale are observed in various stiff clays.A micromechanical stress strain model is developed for modeling the effect of cementation on the deformation behavior of stiff clay.The proposed approach considers explicitly cementations at intercluster contacts,which is different from conventional model.The concept of inter-cluster bonding is introduced to account for an additional cohesion in shear sliding and a higher yield stress in normal compression.A damage law for inter-cluster bonding is proposed at cluster contacts for the debonding process during mechanical loading.The model is used to simulate numerous stress-path tests on Vallericca stiff clay.The applicability of the present model is evaluated through comparisons between the predicted and the measured results.In order to explain the stress-induced anisotropy arising from externally applied load,the evolution of local stresses and local strains at inter-cluster planes are discussed. 相似文献
993.
基于隐马尔可夫模型的地磁匹配算法 总被引:2,自引:0,他引:2
为了在地磁特征微弱区域内实现地磁辅助导航以及提高惯性导航系统在地磁特征明显区域内的定位精度,提出了基于隐马尔可夫模型的地磁匹配算法.首先以惯性导航系统定位误差为隐状态,以实时测量的地磁强度为观测量,建立了地磁匹配的隐马尔可夫模型;其次,针对该模型,使用Viterbi算法来确定最优状态序列,给出了惯性导航系统的当前定位误差.仿真结果表明,该算法可以实现地磁辅助导航,导航误差优于EKF算法,组合导航系统的定位误差在50 m左右. 相似文献
994.
A sol-gel method to synthesize indium tin oxide nanoparticles 总被引:2,自引:0,他引:2
995.
Bao WANG Penghang YIN Andrea Louise BERTOZZI P. Jeffrey BRANTINGHAM Stanley Joel OSHER Jack XIN 《数学年刊B辑(英文版)》2019,40(6):949-966
Real-time crime forecasting is important. However, accurate
prediction of when and where the next crime will happen is
difficult. No known physical model provides a reasonable
approximation to such a complex system. Historical crime data are
sparse in both space and time and the signal of interests is weak.
In this work, the authors first present a proper representation of
crime data. The authors then adapt the spatial temporal residual
network on the well represented data to predict the distribution of
crime in Los Angeles at the scale of hours in neighborhood-sized
parcels. These experiments as well as comparisons with several
existing approaches to prediction demonstrate the superiority of the
proposed model in terms of accuracy. Finally, the authors present a
ternarization technique to address the resource consumption issue
for its deployment in real world. This work is an extension of our
short conference proceeding paper [Wang, B., Zhang, D., Zhang, D.
H., et al., Deep learning for real time Crime forecasting, 2017,
arXiv: 1707.03340]. 相似文献
996.
In[17]and[19,20],the global existence and large time behaviors of smooth compressible fluids(including inviscid gases of Euler equations,viscous gases of Navier-Stokes equations,and rarified gases of Boltzmann equation,respectively)have been established in an infinitely expanding ball with a constant expansion speed.This paper concerns with the viscous fluids in a slowly expanding ball.By involved analy-sis on the density function and the weighted energy estimates,we show that the fluid in the slowly expanding ball smoothly tends to a vacuum state and there is no appearance of vacuum in any part of the expansive ball.Our present result is a meaningful supplement to the one in[19]. 相似文献
997.
The paper is devoted to the study of rational proper holomorphic maps from the unit ball B~n to the unit ball B~N. We classify these maps with both the geometric rank and the degeneracy rank less than or equal to two. 相似文献
998.
Mechanics of Composite Materials - Aiming at the phenomenon of delamination and serious tool wear when processing carbon-carbon composite materials by traditional mechanical tools, an abrasive... 相似文献
999.
1000.
The optimized geometries, complexation energies, etc. of HXPY (X?=?Al, B; Y?=?H, F, OH) donor–acceptor complexes have been investigated at the B3LYP/6-311+G(d,p), MP2/6-311+G(d,p) and/or CCSD(T)/6-311+G(d,p) levels. The results show that HBPY (Y?=?H, F, OH) is more stable than the corresponding HAlPY (Y?=?H, F, OH), F (or OH) substitution on phosphorus results in decreasing complex stability, and the stronger the electron-attracting nature of the substitution atom, the more stable the complex. Moreover, the thermodynamic and kinetic properties of the formation reaction of these donor–acceptor complexes were also examined within the temperature range 200–800?K using the general statistical thermodynamics and Eyring transition state theory with Wigner correction. It is concluded that the formation of HBPY is thermodynamically favoured over that of the corresponding HAlPY, especially at low temperature, and is kinetically favoured over that of the relevant HAlPY (Y?=?H, F, OH), especially at high temperature. 相似文献