Micro/nano-structured montmorillonite/titania particles with high electrorheological activity

A low-cost electrorheological (ER) material made of micro/nano-structured montmorillonite/titania particles was prepared by a one-pot solvothermal method. The micro/nano-structured particles were characterized by X-ray diffraction, Fourier transform infrared spectra, and scanning electron microscopy. It was found that the nanorod-like titania assembled on the surface of montmorillonite, the diameters of the nanorods were about 30 nm, and the lengths were about 300 nm. The electrorheological property of the micro/nano-structured particles in silicone oil was measured under dc electric fields. It was found that the micro/nano-structured montmorillonite/titania ER fluid exhibited much stronger electrorheological effect compared to pure montmorillonite and pure titania nanorod ER fluids, while its leaking current density was significantly lower than that of montmorillonite ER fluid. The stronger electrorheological effect might be attributed to the larger interfacial polarization and interparticle friction, which originated from the unique structure and morphology of micro/nano-structured particles, compared to pure montmorillonite and pure titania nanorods.     

Size effect on the static behavior of electrostatically actuated microbeams

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.     

Micromechanical analysis of the behavior of stiff clay

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.     

Deep Learning for Real-Time Crime Forecasting and Its Ternarization

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].     

On Compressible Smooth Viscous Fluids in Slowly Expanding Balls

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].     

Mappings between balls with geometric and degeneracy rank two

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.     

Finite-Element Analysis and an Experimental Study into the Water Jet Reaming Process of Carbon-Carbon Composites

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...     

两台自私型机器上自私工件排序的PoA紧界

本文研究了两台自私型机器上有自私型工件的关于二元均衡的排序问题。对任意工件序列$L$, 证明了二元均衡排序的PoA的紧界为$\frac{8}{7}$。如果工件尺寸在区间$[1, r](r\ge1)$内, 得到了二元均衡排序的PoA的紧界为关于$r$的分段线性函数。     

Structures and stabilities of the donor–acceptor complexes HXPY (X=Al,B; Y=H,F, OH)

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.