3D finite element simulation of explosive welding of three-layer plates

A 3D finite element model of the explosive welding process of three-layer plates with materials of steel-copper-copper is established. Based on the presented model, the bonding mechanism is simulated and analyzed, different detonation modes are also comparatively studied to indicate the driving force spread in few microseconds. The results show that the three layer plates bond together after many times of impact between the flyers and the base driven by detonation wave, which is damping rapidly at each impa...     

SPH方法研究空气在平板入水中的影响

飞机水上迫降以及船体在高速行驶时,均会发生结构物砰击水面的现象,当结构物底面较为平坦,砰击水面时会捕获空气,在板底形成空气垫。研究空气垫的形成及影响,有助于对结构物进行更准确的载荷分析。该问题的研究涉及到气固液三相的相互作用,在数值模拟中仍是一个挑战,本文使用光滑粒子流体动力学(SPH)方法对该问题进行模拟。首先,与实验结果进行对比;其次,系统地研究了平板形成空气垫以及砰击水面的过程,考查了空气、水和平板的动能变化。对比了在SPH模拟中考虑空气与不考虑空气得到的水压力场和平板所受压力,说明了空气对结果的影响;最后,研究了平板宽度对空气垫形成的影响,从而进一步影响加速度。     

Natural convection heat transfer at reduced pressures

This paper experimentally studies the natural convection heat transfer characteristics on horizontal and vertical plates at pressures lower than atmospheric value. Eight different pressures ranging from 10Pa to 101.325kPa, and three heating loads were used in the experiments. It is found that natural convection heat transfer characteristics at reduced pressures are independent of the plate arrangements and present different behaviors in two pressure ranges, 10Pa < p < 1000Pa and p > 1000Pa. The experimental heat transfer results are correlated into a non-dimensional equation to help the thermal design of stratosphere aircrafts and airborne equipment.     

Long‐time behavior of a nonlinear viscoelastic beam equation with past history

This paper is concerned with the existence of a global attractor for the nonlinear viscoelastic beam equation with past history memory where g(u_t) is a damping like | u_t | ^ru_t and f(u) is a source term like | u | ^αu ? | u | ^βu, by considering 0 ≤ β < α and r > 0. Copyright © 2014 John Wiley & Sons, Ltd.     

Thermal radiation impact on magneto-hydrodynamic heat transfer micropolar fluid flow over a vertical moving porous plate: A finite difference approach

For this research, an examination on the magnetohydrodynamic flow of a micropolar fluid across a moving vertical porous plate for the presence of thermal radiation is achieved. It is necessary to translate the partial differential equations regulating the flow, heat, & mass transfer into dimensionless form employing proper non-dimensional variables, which are then cracked numerically by utilizing the Finite difference approach. Graphs are used to represent numerical values of various flow profiles; however, tables are used to represent the simulated values of rate coefficients. The velocity rises when the value of Grashof number, dimensionless viscosity ratio is raised, and the opposite effect is seen when the value of magnetic parameter, micro-gyration factor is raised. The result in skin friction coefficient improves when the values of magnetic parameter, micro-gyration factor, Prandtl number, and radiation are raised higher.     

Analytical Modelling of Electron-coupled Ion Transfers with Immobilized vs Soluble Redox Transducer at Thick Film-modified Electrodes

Analytical theoretical solutions are deduced for the current-potential response, concentration profiles and interfacial potentials of electron-coupled ion transfers in the cyclic voltammetry with thick film-modified electrodes. The theory covers a wide variety of possible situations, namely, the redox transducer can be either immobilized on the working electrode or freely diffusing in the organic film, and the ion transfer can be either simple or complicated by homogeneous chemical processes. A comparative and comprehensive study of each case is performed, establishing the key parameters that define the behaviour of the system, as well as guidelines to analyse its electrochemical signal.     

Sonocatalytic injury of cancer cells attached on the surface of a nickel–titanium dioxide alloy plate

The present study demonstrates ultrasound-induced cell injury using a nickel–titanium dioxide (Ni–TiO₂) alloy plate as a sonocatalyst and a cell culture surface. Ultrasound irradiation of cell-free Ni–TiO₂ alloy plates with 1 MHz ultrasound at 0.5 W/cm² for 30 s led to an increased generation of hydroxyl (OH) radicals compared to nickel–titanium (Ni–Ti) control alloy plates with and without ultrasound irradiation. When human breast cancer cells (MCF-7 cells) cultured on the Ni–TiO₂ alloy plates were irradiated with 1 MHz ultrasound at 0.5 W/cm² for 30 s and then incubated for 48 h, cell density on the alloy plate was reduced to approximately 50% of the controls on the Ni–Ti alloy plates with and without ultrasound irradiation. These results indicate the injury of MCF-7 cells following sonocatalytic OH radical generation by Ni–TiO₂. Further experiments demonstrated cell shrinkage and chromatin condensation after ultrasound irradiation of MCF-7 cells attached on the Ni–TiO₂ alloy plates, indicating induction of apoptosis.     

In situ X‐ray data collection and structure phasing of protein crystals at Structural Biology Center 19‐ID

A prototype of a 96‐well plate scanner for in situ data collection has been developed at the Structural Biology Center (SBC) beamline 19‐ID, located at the Advanced Photon Source, USA. The applicability of this instrument for protein crystal diffraction screening and data collection at ambient temperature has been demonstrated. Several different protein crystals, including selenium‐labeled, were used for data collection and successful SAD phasing. Without the common procedure of crystal handling and subsequent cryo‐cooling for data collection at T = 100 K, crystals in a crystallization buffer show remarkably low mosaicity (<0.1°) until deterioration by radiation damage occurs. Data presented here show that cryo‐cooling can cause some unexpected structural changes. Based on the results of this study, the integration of the plate scanner into the 19‐ID end‐station with automated controls is being prepared. With improvement of hardware and software, in situ data collection will become available for the SBC user program including remote access.     

高超声速平板边界层流动显示的试验研究

本文在高超声速脉冲式风洞内对基于纳米示踪的平面激光散射技术(nano-based planar laser scattering, NPLS)的应用进行了探索, 并在此基础上对平板边界层流动结构的精细测量进行了研究. 试验来流Ma=7.3, 总压4.8 MPa, 总温680 K. 通过时序的分析和调试, 对各分系统实现了高精度的同步控制; 定量的粒子注入及混合, 实现了粒子的均匀撒播, 对主流获得了均匀的显示效果; 对于边界层流动, 获得了精细的瞬态流动结构图像, 显示了层流到湍流的转捩过程, 并分析了其时空演化特性.     

Conservative numerical methods for the Full von Kármán plate equations

This article is concerned with the numerical solution of the full dynamical von Kármán plate equations for geometrically nonlinear (large‐amplitude) vibration in the simple case of a rectangular plate under periodic boundary conditions. This system is composed of three equations describing the time evolution of the transverse displacement field, as well as the two longitudinal displacements. Particular emphasis is put on developing a family of numerical schemes which, when losses are absent, are exactly energy conserving. The methodology thus extends previous work on the simple von Kármán system, for which longitudinal inertia effects are neglected, resulting in a set of two equations for the transverse displacement and an Airy stress function. Both the semidiscrete (in time) and fully discrete schemes are developed. From the numerical energy conservation property, it is possible to arrive at sufficient conditions for numerical stability, under strongly nonlinear conditions. Simulation results are presented, illustrating various features of plate vibration at high amplitudes, as well as the numerical energy conservation property, using both simple finite difference as well as Fourier spectral discretizations. © 2015 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 31: 1948–1970, 2015