Deflagration-to-detonation transition process for spherical aluminum dust/epoxypropane mist/air mixtures in a large-scale experimental tube

The deflagration-to-detonation transitions (DDTs) for clouds of spherical aluminum dust (SAD) mixed with air or epoxypropane mist (EPM) and air were investigated in a 29.6-m-long experimental tube of 199 mm in diameter. The clouds formed through the injection of SAD and SAD/liquid epoxypropane samples into the experimental tube. Explosions of the SAD/air mixture were initiated using a 7-m-long EPM/air cloud explosion ignited by a 40-J electric spark. Explosions in SAD/EPM/air clouds were initiated using a 1...     

Mixing state of individual carbonaceous particles during a severe haze episode in January 2013,Nanjing,China

Chemical composition,hourly counts,and sizes of atmospheric carbonaceous particles were measured to investigate their mixing state on clear and hazy days.623,122 carbonaceous particles with sizes0.2-2.0 μm was analyzed using a single-particle aerosol mass spectrometer from 1st to 17 th January2013.Particle types included biomass/biofuel burning particles(biomass),element carbon(EC-dominant)particles that were also mixed with biomass/biofuel burning species(EC-biomass) or secondary species(EC-secondary),organic carbon(OC),internally mixed OC and EC(OCEC),ammonium-containing(ammonium) and sodium-containing(sodium) particles.On clear days the top ranked carbonaceous particle types were biomass(48.2%),EC-biomass(15.7%),OCEC(11.1%),and sodium(9.6%),while on hazy days they were biomass(37.3%),EC-biomass(17.6%),EC-secondary(16.6%),and sodium(12.7%).The fractions of EC-secondary,ammonium(10%),and sodium particle types were elevated on hazy days.Numbers of EC-secondary particles were more than four times those on clear days(4.1%).Thus,carbonaceous particles mixed with ammonium,nitrate and sulfate during aging and transport,enhancing their light extinction effects and hygroscopic growth under high relative humidity on hazy days,further reducing visibility.Our real-time single-particle data showed that changes to mixing state had a significant impact on light extinction during haze events in Nanjing.     

SURFACE MODIFICATION AND DISPERSION OF NANODIAMOND IN CLEAN OIL

The effect of different kinds of surfactants on the size distribution of nanodiamond particles in clean oil was studied.Results show that the dispersing stability of nanodiamond modified with surfactangts YS-1 and SB-18 simulta-neously is much better than those modified with either of them because of synergism of the surfactangts.And the particle size distribution in the system can be improved remarkably after the adoption of hyperdispersants such as SA-E and SA-F.Anchoring groups of those hyperdispersants can be bonded with the particle surface by chemical and/or hydrogen bonding and their soluble chains are well compatible with the dispersion media.As a result,the particles are uniformly distrbuted in the system owing to the steric stabilization.A very stable clean-oil based nanodiamond suspension with an average particle size of around 53.2 nm was prepared.     

相变材料接触熔化的研究

对有关相变材料接触熔化的研究成果进行了全面的综述, 内容包括:封闭空间的接 触熔化、围绕热源的接触熔化、滑动接触熔化、滚动接触熔化、冰的压力熔化、接 触熔化的量级分析与修正、由液体边界层内的热扩散引起的熔化、不连续接触点上 熔化与润滑、固体内部传热的影响、玻璃的软化与接触熔化.     

材料的动态损伤和失效

本文对动载荷下材料内部损伤演化过程的研究进行了较为全面、系统的介绍和总结,并对现有的各种动态损伤模型(包括笔者所提出的模型)进行了必要的比较、讨论和评述。     

板壳塑性屈曲中的佯谬及其研究进展

本文详细论述了板壳塑性屈曲中的佯谬及其研究进展。并对现有的各种观点作了分析讨论。     

振动翼型和襟翼的绕流特性研究

用数值模拟手段详细地研究了振动翼型和襟翼的绕流问题,数值模拟的出发方程为Euler和N-S方程,格式为Bcam-Warming格式的改进型。数值实验主要针对流场的二大特性进行的,即振动对激波的影响和振动对分离的抑制作用,结果表明:(1)随翼型或襟翼的振动激波强度和位置也相应地变化但这一变化滞后于攻角的变化;(2)振幅加大激波强度的变化和激波运动范围也加大;(3)振动频率越高对激波的影响反而较低频时要小;(4)流动条件的不同可使升力回线的走向发生变化;(5)振动对分离有明显的抑制作用。     

各向异性本构关系在板料成形数值模拟中的应用

对几种能表达面内各向异性的屈服准则Hill、Barlat-Lian、Barlat进行了比较。以弹性变形服从各向同性广义虎克定律的情况下，给出了基于张量算法推导的弹塑性本构关系的一般表达式，并由此导出了相应屈服准则的弹塑性本构关系的显式表达。借助ABAQUS软件本构模块用户子程序接口，分别实现了这些屈服准则在ABAQUS的嵌入。以模拟方形盒的拉延过程为例，分析了不同的屈服准则在板料成形过程数值模拟中的应用。模拟结果表明，基于弹塑性本构关系一般表达所列出的相应屈服准则的显式表达式是正确的；在采用壳元来模拟板料成形时，采用Barlat准则的模拟结果和采用Barlat-Lian准则的结果差别不大。     

功能纳米材料研究进展——唐智勇研究员及其团队专访

正功能纳米材料是化学、物理、生物和材料科学多学科交叉的前沿,是纳米科技发展的基础。功能纳米材料集中体现了小尺寸、精准控制、高集成度和强相互作用等现代科学技术发展的特点,是将量子力学效应工程化或技术化的最好载体之一,呈现独特的光、电、磁、机械和催化等性质,在物理、生物、化学和材料学领域中都有广泛的研究和应用前景。     

Study of diode-pumped Yb:YAG disk lasers at low temperature

A Yb:YAG disk laser with V-shaped stable resonator and active-mirror configuration,end-pumped by a 940-nm InGaAs laser diode array,is demonstrated.Performances and optimization of the disk laser at low temperature over a range of 130-200 K are investigated theoretically and experimentally.Laser output energy of 1.46 J/pulse operating at 10-Hz repetition rate is obtained with the optimum output coupler transmission of 30%,and the corresponding optical-to-optical efficiency is 48.7%.