基于有限元法确立碳化钨顶锤的破裂判据

以有限元法为理论基础,通过运行大型有限元软件,成功构建了铰链式六面顶压机配套顶锤的有限元理论模型,并确立了碳化钨顶锤的破裂判据。模拟结果表明:以小斜边末尾处为应力参考点,依据第四强度理论,能够对碳化钨顶锤的性能进行更加合理的数值分析。依据此判据可知:在顶锤锤面及小斜边附近,裂纹高发区分布在小斜边附近;在顶锤轴向上,裂纹高发区分布在距离顶锤锤面30 mm处。铰链式六面顶压机配套碳化钨顶锤的有限元模型以及碳化钨顶锤破裂判据的成功构建,为实现新型碳化钨顶锤的设计与研究奠定了基础,对促进实现铰链式六面顶压机腔体大型化具有现实意义。     

等离子体中热阴极鞘层的结构

结合热阴极电子发射理论和等离子体鞘层流体方程研究了热阴极附近存在虚阴极结构时的等离子体鞘层问题,采用Sagdeev势的方法讨论了鞘层解和广义Bohm判据.结果表明,不同于普通的Bohm鞘,由于热阴极附近存在大量发射电子,影响整个等离子体鞘层结构,使得进入鞘层的离子临界Mach数不是独立的常数,而是与鞘层电位降等参数有关的物理量.临界Mach数随着鞘层电位降（从鞘边缘到虚阴极）先增大后降低,并且随着热阴极温度的升高单调增大.此外,在平板模型下有相当可观的残余热发射电子越过虚阴极鞘层进入等离子体. 关键词： 鞘层 热阴极发射 Bohm判据     

光度法同时测定铂和钯

水溶性试剂N-间甲苯基-N’-(对氨基苯磺酸钠)硫脲(MMPT)在HAc-NaAc缓冲介质和CTMAB(溴化十六烷基三甲胺)存在下,与铂(Ⅳ)和钯(Ⅱ)反应形成绿色和褐色水溶性络合物,其最大吸收波长分别为754.4和304.6 nm。符合比尔定律的浓度范围分别为0～32 μg·(25 mL)-1, 0～25 μg·25(mL)-1,摩尔吸光系数为εPt_754.4=8.6×104 L·mol-1·cm-1和εPd304.6=7.4×104 L·mol-1·cm-1。在754.4和304.6 nm波长测定铂,钯混合液的吸光度,换算出铂、钯的含量。50种共存离子中, 仅有Cu2+和Co2+ 对钯的测定有干扰。该法选择性好,用于合成样品、矿石和催化剂样品中铂、钯含量的测定, 其相对标准偏差RSD小于2.0%;回收实验回收率是96%～104%。由于试剂铂、钯形成的络合物都易溶于水、不需予先分离同时测定,操作简便,快速,且环境友好。     

次谐波聚束系统固态放大器相位特性

 为研究BEPCⅡ直线加速器次谐波聚束系统使用的两台固态放大器（20 kW/142.8 MHz,10 kW/571.2 MHz）的相位特性,利用基于现场可编程门阵列(FPGA)的数字测量方法对两台固态放大器的脉内相移和相位稳定度进行了测量。测量系统硬件包括频率综合器、FPGA数字信号处理板和PC;软件部分包括FPGA内部算法、通信及PC端界面程序。该测量系统能真实地反映两台固态放大器的相位特性,为次谐波聚束器的相位补偿提供了参考。     

含氢添加剂对合成cBN的影响及腔体温度分布

 通过对Li基触媒下立方氮化硼的高温高压合成实验结果的分析,研究了在Li基触媒作为主要触媒及氢化物作为添加剂的环境下,立方氮化硼的生长情况。同时由合成后样品中立方氮化硼的生成区域对V型生长区温度梯度分布进行了分析讨论。     

高功率Nd∶YVO4/KTP腔内倍频晶体温度分布的半解析热分析

非线性晶体KTP采用Ⅱ类相位匹配腔内倍频时,不仅要求晶体满足基频光的偏振匹配条件,而且所选用的晶体要求符合λ/2波片的条件,才能使晶体的谐波转换效率达到最佳.由于倍频晶体吸收基频光能量引起晶体内部非均匀温升,改变晶体内部各点的折射率,也会使晶体产生不应有的热形变,破坏晶体初始的位相匹配条件,严重影响输出激光的品质和倍频效率.减弱、改善这种情况的关键是准确得出在实际工作条件下晶体内部温度场.利用半解析热分析方法得出了KTP晶体内部温度场的计算方法,分析了各种热参量变化对KTP晶体内部温度场的影响.得出的结果具有一定的普适性,可以应用到具有轴对称形式内热源的其它热模型温度场的计算分析中,对连续波腔内倍频激光系统的设计将起到指导作用.     

Spectra of Highly Ionized Sulfur below 200 ^。A

Spectra of carbon-,boron-,beryllium-,lithium-,helium-,and hydrogen-like sulfur ions were obtained and studied for the wavelengths below 200 ^。A and the energy of 8O Me V by using beam-foil method.Thirty-five lines have been identified,in which 15 lines are newly accurately measured.The spectra were analysed based on the theoretical results and other experimental data.     

Discovery of Multiple outflows in IRAS 06056＋2131

We report a discovery of multiple outflows in IRAS 06056 2131. The high angular resolution image (～ 15“) of CO(1-0) emission reveals that the structure of outflow is very complicated. The outflow appears to be everywhere.Its configuration only show a bipolar outflow at observation of both low resolution and low signal-to-noise ratio,while two bipolar outflows can be detected when observed by both high resolution and high signal-to-noise ratio mapping. This result is significant in the understanding of the physical processes that occur at early phase of massive stars.     

Isoscalar Giant Resonances of ^120Sn in the Quasiparticle Relativistic Random Phase Approximation

The quasiparticle relativistic random phase approximationmean field ground state in the response function formalism(QRRPA) is formulated based on the relativistic The pairing correlations are taken into accountin the Bardeen-Cooper-Schrieffer approximation with a constant pairing gap. The numerical calculations are performed in the case of various isoscalar giant resonances of nucleus ^120Sn with parameter set NL3. The calculated results show that the QRRPA approach could satisfactorily reproduce the experimental data of the energies of low-lying states.     

Synthesis and characterization of p-type boron-doped IIb diamond large single crystals

High-quality p-type boron-doped IIb diamond large single crystals are successfully synthesized by the temperature gradient method in a china-type cubic anvil high-pressure apparatus at about 5.5 GPa and 1600 K.The morphologies and surface textures of the synthetic diamond crystals with different boron additive quantities are characterized by using an optical microscope and a scanning electron microscope respectively.The impurities of nitrogen and boron in diamonds are detected by micro Fourier transform infrared technique.The electrical properties including resistivities,Hall coefficients,Hall mobilities and carrier densities of the synthesized samples are measured by a four-point probe and the Hall effect method.The results show that large p-type boron-doped diamond single crystals with few nitrogen impurities have been synthesized.With the increase of quantity of additive boron,some high-index crystal faces such as {113} gradually disappear,and some stripes and triangle pits occur on the crystal surface.This work is helpful for the further research and application of boron-doped semiconductor diamond.