基于准静态波的吸气式高重频脉冲激光推进性能数值研究

 根据高重频脉冲激光产生光学脉冲放电形成准静态波的原理,对自编的流体力学计算程序进行了验证,结果表明该程序可用于吸气式高重频脉冲激光推进性能的数值研究。分别计算了基于移动点火点和喷射气流两种模式下准静态波流场的冲量耦合系数,均高达600 N/MW,比传统的低频脉冲激光推进冲量耦合系数250 N/MW高。比较了两种模式的优缺点,给出了不同模式的适用情况,结果表明,对于机理研究来说,喷气模式更易于实现。     

CMSH:Ni2+的光谱及其局域结构的研究

采用晶场参量的重叠模型,建立了结构参数与光谱之间的定量关系;利用完全对角化方法,由光谱确定CMSH:Ni2 晶体中[Ni(H2O)6]2 络离子在温度为77 K时的局域结构参数,较好地解释了CMSH:Ni2 晶体的局域结构和光学吸收谱;研究结果发现,CMSH:Ni2 晶体中络离子[Ni(H2O)6]2 的键长为R≈0.2047 nm,键角θ≈54.9°;所得光谱的理论结果与实验结果符合得非常好.     

过氧化氢加酒精补燃气体发生器实验研究

 介绍了过氧化氢催化分解气体加酒精补燃以提高气体发生器排气温度的理论计算和分析方法,并建立了一套实验研究装置。 装置中质量分数为90%的过氧化氢溶液由高压气挤推,通过催化床完成催化分解,产生高温气体;质量分数为97%的酒精溶液经由分布喷嘴喷入过氧化氢分解气体中发生自燃,从而提高气体温度。实验研究了采用不同酒精喷入形式和参数对气体发生器排气温度均匀性的影响。结果表明：利用沿气体发生器燃烧室周向分布的多喷嘴进行酒精喷注,并与高浓度过氧化氢催化分解气体进行混合燃烧的方法,能够有效提高气体发生器的排气温度,并得到均匀的排气温度场。     

吹气抑制气体热效应时管道结构对光传输的影响

 采用吹气抑制气体热效应对光传输的影响时,管道结构会对内通道流场分布产生作用从而影响光传输质量。对比研究了沿几何尺寸相同、光路总长相等的U形和Z形管道轴向吹气的情形。仿真过程中,联合求解标量衍射方程和N-S方程,计算管道对吹气流场的影响以及流场对光束的影响,以远场光斑的峰值功率密度点、能量分布重心点位置的偏移以及Strehl比和b值的变化反映光束质量。结果表明:不吹气时,管道结构对流场的影响远小于气体吸热对流场的影响;吹气时,管道内气体流速较大,管道结构对流场分布的影响比较明显;吹气时,U形管道对光束的影响比Z形管道对光束的影响要小。     

Enzymolysis kinetics,thermodynamics and model of porcine cerebral protein with single-frequency countercurrent and pulsed ultrasound-assisted processing

The present work investigated the enzymolysis kinetics, thermodynamics and model of porcine cerebral protein (PCP) which was pretreated by single-frequency countercurrent and pulsed ultrasound. The kinetic constants for ultrasonic pretreated and traditional enzymolysis have been determined. Results showed that the value of K_M in ultrasonic PCP (UPCP) enzymolysis decreased by 9% over that in the traditional enzymolysis. The values of reaction rate constant (k) for UPCP enzymolysis increased by 207%, 121%, 62%, and 45% at 293, 303, 313 and 323 K, respectively. For the thermodynamic parameters, ultrasound decreased activation energy (E_a), change in enthalpy (ΔH) and entropy (ΔS) by 76%, 82% and 31% in PCP, respectively. However, ultrasound had little change in Gibbs free energy (ΔG) value in the temperature range of 293–323 K. Therefore, a general kinetic equation for the enzymolysis model of UPCP by a simple empirical equation was suggested. The experimental values fits with the enzymolysis kinetic model with a low average relative error (4%) confirmed that the kinetic model was accurate to reflect the enzymolysis process. The positive effect of single-frequency countercurrent and pulsed ultrasound in this study and application of the kinetic model may be useful for the release of bioactive peptides from meat processing by-products.     

便携式数控系统ARM监控平台的设计

在数控系统中,通常需要利用串口或者CAN总线进行数据监控,针对满足其数据采集与发送及存储的技术要求,提出一种便携式的数控系统监控平台设计方法;基于Freescale的ARM芯片MCIMX357与Linux操作系统,利用外围接口电路,实现大容量数据存储、串口多模式通信、CAN总线数据监控,同时附加人机友好界面,利用配套电源管理方案实现低功耗便携功能;通过测试表明设计合理可靠,功耗为3.5W,串口通信频率为115200bps,CAN通信速度为500K,同时该设计成果成功应用于我单位某型数控系统中。     

Does roughening of rock-fluid-rock interfaces emerge from a stress-induced instability?

Non-planar solid-fluid-solid interfaces under stress are very common in many industrial and natural materials. For example, in the Earth’s crust, many rough and wavy interfaces can be observed in rocks in a wide range of spatial scales, from undulate grain boundaries at the micrometer scale, to stylolite dissolution planes at the meter scale. It is proposed here that these initially flat solid-fluid-solid interfaces become rough by a morphological instability triggered by elastic stress. A model for the formation of these unstable patterns at all scales is thus presented. It is shown that such instability is inherently present due to the uniaxial stress that promotes them, owing to the gain in the total elastic energy: the intrinsic elastic energy plus the work of the external forces. This is shown explicitly by solving the elastic problem in a linear stability analysis, and proved more generally without having resort to the computation of the elastic field.     

基于光声光谱技术的1.5 μm波段 NH3吸收谱线测量与分析

NH₃的检测具有广泛的应用,采用光声法检测NH₃是当前研究的热点,而确定NH₃的吸收谱线则是实现光声法检测NH₃的前提。采用外腔可调谐半导体激光器构造了光声气体检测系统,检测了NH₃的近红外吸收谱线,获得了常温常压下NH₃在1 515~1 532 nm范围内的吸收光谱。实验确认了NH₃在1 515.2,1 516.0,1 518.0,1 519.9,1 522.4,1 527.0,1 531.7 nm处存在强吸收。HITRAN 2004光谱数据库在近红外1.5 μm波段NH₃的吸收谱线数据未见报道,该结果为研究光声法检测NH₃提供了更多可选择的吸收谱线。     

(分块)非负矩阵谱半径的界

<正>1引言若A=(a_(ij)),其中a_(ij)≥0,我们则称A为非负矩阵.ρ(A)表示A的谱半径,当A≥0时,ρ(A)就是A的Perron根.众所周知,若A≥0,则r_(min)(A)≤ρ(A)≤r_(max)(A),     

高焓流场氧原子激光诱导荧光技术初步研究

基于双光子吸收激光诱导荧光(TALIF)技术,在纯净的高焓流场环境中,将脉冲激光从垂直于流场方向射入流场,并通过布置在风洞试验段外与流场和激光形成的平面向垂直方向上的ICCD测量获取到了二维氧原子的荧光信号,该信号可以反映氧原子相对浓度。为保证实验中使用到的激发激光波长为最佳激发波长,分别对氧原子基态处在不同角量子数的情况进行了测试,最终确定J=2时,波长为225.584 nm为最终实验激发波长,为了保证所获取的氧原子荧光信号在非饱和线性区,在同种状态下,将激发激光能量从小到大调整并进行荧光信号的测试,获取了激光能量在3.4 mJ以下的线性区域。为确保获取清晰对比度最优的ICCD荧光图像,选择了Nikon f=105 mm F/2.8镜头为实验测试镜头, 同时将50次曝光的累计结果作为图像输出。对所获取的荧光图像进行分析,实验结果可以清晰地看到超声速流场中压缩波形成的距中心线约±50 mm位置处左右各一个的小峰,亚声速流场中中心处氧原子浓度有一个约60 mm宽的均匀区域,区域以外氧原子浓度急剧下降,这些结果符合实验风洞特性,此测试方法可以很好地运用到流场测量中。