Ultrasound imaging and evaluation of lesion induced by High Intensity Focused Ultrasound

The present study was to investigate the differential imaging method for detecting HIFU (High Intensity Focused Ultrasound)-induced lesions and the estimation of variation of attenuation for lesion evaluation with log spectral difference algorithm. Experiment results of bovine muscle and liver in vitro were acquired. Several algorithms for lesion detection - Absolute Difference (AD), Sum Absolute Differences (SAD) and Sum Squared Differences (SSD) - were analyzed with several window sizes and threshold values. Then three attenuation parameters were compared to evaluate the degree of tissue damage. It was found that variation of the mean attenuation △α was an effective parameter to evaluate lesions.     

乌桕类可可脂结晶过程中表现体积变化

为了解乌桕类可可脂(CTCBE)缓冷结晶横向胀罐爆裂原因，研究CTCBE结晶过程中的膨胀特性，采用流体静力法测试了不同等温结晶条件下CTCBE结晶形成的表观密度和表观体积及其横纵向膨胀状况。结果表明，CTCBE缓冷结晶后形成外部和中部两个晶区。在5-25℃的各等温结晶范围内，当结晶温度增加时，外部结晶区域减小、表观密度变化不大；中部结晶区域增大、表观密度明显减小，CTCBE的表观体积、横向、纵向膨胀率均增大，膨胀横向大于纵向。进一步表明CTCBE在自然缓冷固化的表观体积根本上由其结晶温度决定。为有效防止横向胀罐，自然缓冷固化温度应低于10℃。     

强流四脉冲电子束源实验研究

 为了进行强流多电子束源研究，对现有2MeV LIA 注入器进行了四脉冲改造，二极管脉冲电压约500kV。实验研究了天鹅绒阴极在四脉冲条件下的发射能力、传导电流负载效应以及阴极等离子体运动对阴极电子发射和束能量的影响。利用空间电荷限制流模型推算出阴极等离子体膨胀速率在1 ~4cm/μs之间。     

一个膨胀的热夸克物质的双轻子谱的研究

一个从能量-动量守恒导出的,用来描写一个膨胀的热夸克物质的相对论性的流体力学方程被普遍化,使之包括粒子数守恒.基于新的描述,我们研究了潜热和粒子分布在谱上的效应.计算表明,要获得一个合理的关于夸克物质形成的预言,这些效应是必须考虑的.     

Residual stress profiling of an aluminum alloy by laser ultrasonics

A residual-stress profile along the thickness of an aluminum alloy sheet is determined by laser-ultrasonic technique. Surface acoustic waves are generated by a Nd:YAG pulse laser and detected by a Heterodyne interferometer on a lateral free surface of the sheet. The distribution of residual stress is determined by measuring the relative variation of the wavevelocities at different location of the sample along its thickness. This technique is validated by three different residual stress profiles obtained experimentally.     

混凝土靶球形腔膨胀侵彻模型应用

Bishop等人于1945年开始用解析方法研究侵彻机理，导出了柱形腔和球形腔的准静态v膨胀方程，后来这种方法被称为空腔膨胀理论。目前，空腔膨胀理论已经在多种不同材料靶的侵彻研究中获得较为普遍的应用。Forrestal等人于1997年提出了一个适用于混凝土材料靶的球对称空腔膨胀侵彻模型，模型对靶结构的描述是将其压力与体积应变的关系理想化为不可压或线性可压，而将剪切强度与压力的关系理想化为由一拉伸阈值表示的Mohr-Coulomb准则。     

Decomposition of the Two Lowest Lamb modes in a Bonded Plate

Based on the expression of the dispersion equation of Lame waves in an adhesive two-layered plate pressented in our proevious paper [Chin,Phys,Lett,18(2001)1483],the two lowest Lamb modes,the symmetric mode S0 and the antisymmetric mode A0 are successfully decomposed in the low-frequency regime,Relations between the rigidity of the bond and the velocity of the two Lamb modes are found,which lay a foundation for the estimation of the bond rigidity of the adhesive plate.The influence of the variations of the bond rigidity in terms of the stiffness constants KN and KT of the spring model on the velocity of the two Lamb modes in discussed and numerically evaluated.numerical results indicate that the deterioration of the bond rigidity causes the phase velocity decrease for Lamb modes of the two lowest order,thus having a possibility for the evaluation of the bonding state of the adhesive plate by using ultrasonic wave velocity measurement.     

The First Results of Supersonic Molecular Beam Injection in the HL-2A Tokamak

HL-2A tokamak, the first tokamak with divertor in China, has been constructed and put into operation in 2002. The main parameters are R=1.65 m, a=0.4 m, BT=2.8 T, Ip = 0. 48 MA. The divertor of HL-2A is unique, because it is characterized with a large closed divertor chamber. The device has double divertor chamber, but now it is operating with lower single null configuration to study the physics of divertor for the next step design of a divertor. Supersonic molecular beam injection （SMBI） system with LN2 cooling trap was first installed and demonstrated on the HL-2A tokamak in 2004. The first results of SMBI into HL-2A plasma are to demonstrate the function of the HL-2A divertor and to observe the cold pulse propagation during multi-pulse SMBI on HL-2A Tokamak.     

狭义相对论效应──运动时钟变慢的计算机模拟演示实验

利用精炼的C语言进行程序设计，定量模拟狭义相结论的运动时钟变慢，并对处于两种不同时空观的时钟运行进行对比，使得时间膨胀效应变得直观。     

双频超声交替强化超临界流体萃取装置的设计与应用

本文针对超临界流体萃取（SFE）系统设备的特点，设计丁可用于强化SFE过程的双频超声波交替强化装置。以香椿叶中黄酮类化合物为提取对象，对超声强化USFE过程的影响因素及强化效果进行了实验研究，结果表明；低频超声利于提取，频率为20kHz的超声强化的萃取率最大，38kHz的超声最小，两者交替的居于中间。