Medium temperature dependence of quark energy loss

By using the reaction operator approach and the single hard scattering approximation scenario, we study the medium temperature dependence of heavy quark radiation energy loss via introducing the medium temperature into QCD running coupling α _s and Debye mass μ _D . Our results indicate that there exist an equilibrum temperature T = 320 MeV in Au-Au collisions withe energy 130 GeV at RHIC, which is agreement with the prediction from hydrodynamic model. We also find that, in the low p _t region, the color coupling effect dominates the heavy quark radiation energy loss, and the energy loss will be dominated by the Debye screening effect when the quark p _t become large.     

The multi-dimensional limiters for solving hyperbolic conservation laws on unstructured grids

Novel limiters based on the weighted average procedure are developed for finite volume methods solving multi-dimensional hyperbolic conservation laws on unstructured grids. The development of these limiters is inspired by the biased averaging procedure of Choi and Liu [10]. The remarkable features of the present limiters are the new biased functions and the weighted average procedure, which enable the present limiter to capture strong shock waves and achieve excellent convergence for steady state computations. The mechanism of the developed limiters for eliminating spurious oscillations in the vicinity of discontinuities is revealed by studying the asymptotic behavior of the limiters. Numerical experiments for a variety of test cases are presented to demonstrate the superior performance of the proposed limiters.     

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.     

Description of yield surface evolution using a convected plasticity model

The convected plasticity model proposed by Wu, 2003a, Wu, 2003b, Wu, 2005, Wu, 2007, making use of convected coordinate system, is applied to discuss the evolution of yield surface. It is shown that this constitutive model is capable of describing all experimentally observed features of subsequent yield surface: isotropic hardening, kinematic hardening, distortion, and rotation of yield surface. The rotation of yield surface in 3D stress space has not been much discussed in the literature, but recent experiments at National Taiwan University (Sung et al., 2011) have shown that it is an important property of subsequent yield surface. In particular, the rotation of subsequent yield surface is pre-strain path dependent. It does not rotate, when the pre-strain is tensile; but the yield surface rotates about the axial stress axis when the pre-strain is torsional.     

用各向同性材料实现宽带声波功能器件设计

利用坐标变换的方法并结合保角映射技术,论文介绍了一种利用常规的各向同性材料来设计声波器件的方法.基于此理论,设计了二维声波隐身斗篷,并进行有限元模拟,证明了该器件的有效性.另外由于设计中没有利用材料共振的性质,所以器件是宽带有效的.该方法将有助于拓宽声波功能器件的设计,并为实验验证声波器件提供了可能.     

高速流场气动光学RANS/DSMC混合数值模拟算法研究

提出了适用于高速流场气动光学数值模拟的RANS/DSMC混合算法.通过RANS对全局时均流场进行数值模拟,再对其中局部流场的脉动量采用DSMC进行数值模拟,以Maxwellian速度分布实现RANS宏观量信息向DSMC微观量信息的传递.采用超声速环境下尖劈模型对该混合算法进行校验,对比试验结果论证了算法的正确性.在计算...     

基于改进卡尔曼滤波的汽车路试制动性能检测方法

针对传统汽车路试制动性能检测方法的不足,提出了一种基于改进卡尔曼滤波的汽车路试制动性能检测方法。根据卡尔曼滤波理论,以单频载波相位单点GPS接收机输出的速度和方位角作为观测量,通过改进的卡尔曼滤波递推算法高频率、高精度地推算出汽车制动过程的平面运动坐标和速度,进而确定汽车制动距离和平均减速度MFDD,以检测汽车的制动性能。实车试验表明,该方法的制动距离测量精度可达0.2~0.3 m,速度精度小于0.1 m/s,输出频率可达100 Hz,具有成本低、输出频率高、精度高、环境适应力强的优点,克服了传统方法的不足。     

民用飞机发动机吊挂静力试验技术研究

根据民用飞机发动机吊挂部段静力试验技术需求,研制了一套用于吊挂部段静力试验的试验系统,解决了吊挂支持模拟、加载边界模拟等关键技术;采用载荷偏移与力偶施加相结合的方法施加力矩;设计了加载杠杆施加试验小载荷.顺利完成了吊挂应急着陆、航向侧移相关的三种危险工况试验.试验结果表明,试验系统工作稳定可靠,吊挂在应急着陆等工况下未发生有害塑性变形,其强度、刚度满足设计要求.试验结果可作为该吊挂部段强度、刚度性能的评定依据,同时为有限元建模提供数据支持.     

Mussel‐inspired method to decorate commercial nanofiltration membrane for heavy metal ions removal

Nanofiltration (NF) membranes have been widely used for the treatment of electroplating, aerospace, textile, pharmaceutical, and other chemical industries. In this work, halloysite nanotubes (HNTs) were directly anchored on the surface of commercial nanofiltration (NF) membrane by dopamine modification following advantageous bio‐inspired methods. SEM and AFM images were used to characterize the HNTs decorated membrane surface in terms of surface morphology and roughness. Water contact angle (WCA) was employed in evidencing the incorporation of HNTs and dopamine in terms of hydrophilicity or hydrophobicity. Augmentation of HNTs was found to obviously enhance the hydrophilicity and surface roughness resulting in improved water permeability of membrane. More importantly, the rejection ratios of membrane also increased during the removal of heavy metal ions from wastewater. The permeability and Cu²⁺ rejection ratio of modified NF membrane were as high as 13.9 L·m^?2·h^?1·bar^?1 and 74.3%, respectively. Incorporation of HNTs was also found to enhance the anti‐fouling property and stability of membrane as evident from long‐term performance tests. The relative concentration of HNTs and dopamine on membrane surface was optimized by investigating the trade‐off between water permeability and rejection ratio.