经典自动机理论中构件在弹簧作用下运动分析

指出了经典自动机理论中构件在弹簧作用下运动方程分压缩和伸张过程分别建立,以及引入弹簧做功效率处理方程均存在很大的不便性,并提出用振动理论中线性阻尼系统来研究自动机构件在弹簧作用下运动的思路,使方程形式更为统一,处理更为简单,最后用一个计算实例说明了该方法的可行性。

扣件式脚手架坍塌原因分析与措施

通过分析扣件式脚手架各组构件作用和架体结构特点,总结了导致脚手架坍塌的人为因素,并提出施工和管理上的建议措施,以期减少脚手架坍塌事故。

考虑模具和黏弹性的复合材料固化变形数值模型

考虑了模具作用和材料的黏弹性,建立了复合材料构件残余应力和固化变形的三维数值模型。在模具与复合材料构件间引入界面剪应力,模拟升温过程中模具-构件的相互作用。分析了固化过程中温度和固化度对材料力学性能的影响,分别采用线弹性和黏弹性本构方程描述凝胶前后材料的应力-应变关系。采用热-力顺序耦合分析方法,在ABAQUS软件中建立了模拟复合材料固化过程的有限元模型,分析了固化过程中温度场、固化度场、残余应力及变形。最后,通过与试验结果的对比,验证了所建数值模型的合理性和准确性。结果表明,固化过程中单向板和非对称层合板内产生的残余应力在厚度方向上呈非对称分布,这是脱模后层合板变形的根本原因。

Numerical Simulation of Geotechnical Problems by Coupled Finite and Infinite Elements

in geotechnical engineering, numerical simulation of problems is of great importance. This work proposes a new formulation of coupled finite-infinite elements which can be used in numerical simulation ofgeotechnical problems in both static and dynamic conditions. Formulation and various implementation aspects of the proposed coupled finite-infinite elements are carefully discussed. To the authors＇ knowledge, this approach that considers coupled finite-infinite elements is more efficient in the sense that appropriate and accurate results are obtained by using less elements. The accuracy and efficiency of the proposed approach is considered by comparing the obtained results with analytical and numerical results. In a static case, the problem of circular domain ol infinite length is considered. In a dynamic case, one dimensional wave propagation problems arising from the Heaviside step fimction and impulse functions are considered. In order to get a more complete picture, two dimensional wave propagation in a circular qtmrter space is considered and the results are presented. Finally, a soil-structure interaction system subjected to seismic excitation is analyzed. In the analysis of soil-structure interaction phenomenon, frames with different number of storeys and soil media with various stiffness characteristics have been taken into consideration. In the analysis, the finite element software ANSYS has been used. For the newly developed infinite element, the programming has been done by the help of the User Programmable Features of the ANSYS software, which enable creating new elements in the ANSYS software.

Influence of substrate temperature on the deposition and structural properties of μc-Si:H thin films fabricated with VHF-PECVD

With in situ optical emission spectroscopy （OES） diagnosis on VHF-generated H2 ＋ SiH4 plasmas,and with the measurements of deposition rate and structure of μc-Si. H thin films fabricated with VHFPECVD technique at different substracte temperature, influence of substrate temperature on the deposition of μc-Si.H thin film and on its structural properties have been investigated. The results show that with the increase of substrate temperature,the crystalline volume fraction Xc and average grain size d are enhanced monotonously, but the deposition rate increases firstly and then decreases. The optimized substrate temperature for μc-Si：H thin films deposition under our current growth system is about 210 ℃ ,at which deposition rate O. 8 nm/s of pc-Si;H thin film with Xc-60% and d-9 nm can be obtained.

Bcklund Transformation and Multisoliton Solutions in Terms of Wronskian Determinant for (2+1)-Dimensional Breaking Soliton Equations with Symbolic Computation

In this paper, two types of the （2＋1）-dimensional breaking soliton equations axe investigated, which describe the interactions of the Riemann waves with the long waves. With symbolic computation, the Hirota bilineax forms and Bgcklund transformations are derived for those two systems. Furthermore, multisoliton solutions in terms of the Wronskian determinant are constructed, which are verified through the direct substitution of the solutions into the bilineax equations. Via the Wronskian technique, it is proved that the Bgcklund transformations obtained are the ones between the （ N - 1）- and N-soliton solutions. Propagations and interactions of the kink-/bell-shaped solitons are presented. It is shown that the Riemann waves possess the solitonie properties, and maintain the amplitudes and velocities in the collisions only with some phase shifts.

Research on Optimization wharf Structure Type of Triangle frame pier

Based on optimization wharf structure type of triangle flame pier proposed, namely＂ Spatial triangular flame pier ＋ Big span bent which taking Slant supports＂ Simulating three-dimensional pier model of a variety of conditions in the actual loading by structural finite element software. Under the guidance of the three-dimensional structure of the most unfavorable load combination algorithm, three-dimensional combination algorithm is applied to the new structure by the MATLAB software programming. Search and calculate the most unfavorable combination of action effects and the corresponding intemal force of the main member, checking the feasibility of the three-dimensional algorithms, Calculating the new wharf structure structural features and stability, Providing numerical reference for the design of this sort of wharf.

热固性树脂基复合材料固化变形解析预测研究进展

在外部成型条件和内部材料各向异性的影响下,脱模后复合材料构件不可避免的产生固化变形,解析预测方法可以快速的预估复合材料的固化变形并能解释其潜在的变形机制,因而被广泛研究。本文介绍了热固性复合材料固化变形的产生因素和来源,并重点了详述了平板和曲型复合材料构件固化变形解析预测方法的最新进展,并分析其优缺点,为复合材料固化变形预测提供方向和参考。最后简要讨论了当前复合材料固化变形解析预测的主要发展方向。

Antibacterial applications of graphene oxides: structure-activity relationships, molecular initiating events and biosafety

Bacterial infections may lead to diverse acute or chronic diseases （e.g., inflammation, sepsis and cancer）. New antibiotics against bacteria are rarely discovered in recent years, which necessitates the exploration of new antibacterial agents. Engineered nanomatetials {ENMs） have been extensively studied for antibacterial use because of their long lasting killing effects in wide spectra of bacteria. Graphene oxide （GO） is one of the most widely studied ENMs and exhibit strong bactericidal effects. The physicochemical properties of GO play important roles in bacterial killing by triggering a cascade of toxic events. Many studies have explored the signaling pathways of GO in bacteria. Although molecular initiating events （MIEs） of GO in bacteria dominate its killing efficiency as well as toxicity mechanisms, they have been rarely reviewed. In this report, we discussed the structure-activity relationships （SARs） involved in GOinduced bacterial killing and the MIEs including redox reaction with biomolecules, mechanical destruction of membranes and catalysis of extracellular metabolites. Furthermore, we summarized the clinical or commercial applications of GO-based antibacterial products and discussed their biosafety in mammal. Finally, we reviewed the remaining challenges in GO for antibacterial applications, which may offer new insights for the development of nano antibacterial studies.

Pressure Boundary Conditions for Blood Flows

Simulations of blood flows in arteries require numerical solutions of fluidstructure interactions involving Navier-Stokes equations coupled with large displacement visco-elasticity for the vessels.Among the various simplifications which have been proposed, the surface pressure model leads to a hierarchy of simpler models including one that involves only the pressure. The model exhibits fundamental frequencies which can be computed and compared with the pulse. Yet unconditionally stable time discretizations can be constructed by combining implicit time schemes with Galerkin-characteristic discretization of the convection terms in the Navier-Stokes equations. Such problems with prescribed pressure on the walls will be shown to be efficient and accurate as an approximation of the full fluid structure interaction problem.

Elastic-plastic seismic response of CRTS II slab ballastless track system on high-speed railway bridges

China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.