Comparison of emission signals for different polarizations in femtosecond laser-induced breakdown spectroscopy

In this study, a femtosecond laser was focused to ablate brass target and generate plasma emission in air. The influence of lens to sample distance(LTSD) on spectral emission of brass plasma under linearly and circularly polarized pulses with different pulse energies was investigated. The results indicated that the position with the strongest spectral emission moved toward focusing lens with increasing the energy. At the same laser energy, the line emission under circularly polarized pulse was stronger compared with linearly polarized pulse for different LTSDs. Next, electron temperature and density of the plasma were obtained with Cu(Ⅰ) lines,indicating that the electron temperature and density under circularly polarized pulse were higher compared to that under linearly polarized pulse. Therefore, changing the laser polarization is a simple and effective way to improve the spectral emission intensity of femtosecond laserinduced plasma.     

蜗形凸轮的误差分析

运用坐标变换和包络原理对蜗形凸轮进行误差分析,提出了一种加工误差的计算方法,为保证蜗形凸轮的加工精度具有一定的意义。     

非线性阻尼结构系统在随机振动条件下可靠度的估算

阐述了在白噪声特征的稳态随机激励下,两种非线性阻尼结构参数统计的不确定性,分析了它们对系统可靠度估算的影响;运用Ｆｏｋｋｅｒ－Ｐｌａｎｃｋ方程,推导了响应的概率密度函数;可靠度估算中考虑了两种失效机理：即超越门槛值失效和疲劳失效,并采用“两步记忆过程”确定超越概率。结果表明,非线性阻尼对可靠度估算的影响极大．     

悬臂板固有特性几种情况的分析比较

采用两种有限元（矩形板弯元、三角形板弯元）和两种质量矩阵形式（集中质量矩阵、一致质量矩阵）计算等厚度方形悬臂板的固有频率和固有振型，对四种单元／质量矩阵组合形式的固有特性进行了分析比较；指出这些组合形式的数值解与理论解相比产生误差的原因及其改进办法；对变厚度正方形悬臂板（翼面）和等厚度梯形悬臂板（翼面）的固有特性作了启示性分析说明；从中看出不同结构形式悬臂板的固有特性的特点。     

加拿大一枝黄花制浆研究(系列报道之二)碱法蒸煮工艺技术参数的研究

对加拿大一枝黄花碱法蒸煮性能进行了研究。探讨了保温时间、最高温度和用碱量对浆料性能的影响。得到AP法适宜的蒸煮工艺为：用碱量17％（以Na2O计），最高温度160℃下保温120min，其蒸煮结果是：得率49．08％．卡伯值45．4，残碱8．49g／L（以Na2O计）。KP法适宜蒸煮条件为：用碱量17％（以Na2O计），最高温度160℃下保温90min，硫化度20％，其蒸煮结果：得率48．56％，卡伯值28．8，残碱7．32g／L（以Na2O计）。KP法是加拿大一枝黄花较适宜的蒸煮方法。     

NUMERICAL STUDY FOR THE NONLINEAR EVOLUTION OF VORTEX SHEET AND ITS APPLICATIONS: PART II. EVOLUTION OF WING SHEDDING VORTEX

1.　 INTRODUCTIONVortex sheet exists widely in a variety of nature and engineering problems,which isusually shed from airplane wing,ship propeller,swim ming fish,and so on.To study thebehaviour of vortex sheetevolution is much helpful to understand the physical mechanism ofthose flows.Therefore,many vortex m ethods[1 - 5 ] ,even involving viscous effects,weredeveloped to simulate the vortex sheet motion.As was discussed in Part I,asuperconvergence scheme based on Multhopp′s discretizati…     

一株大质粒决定的耐镉假单胞菌的鉴定与耐受性分析

分离到一株耐镉菌株XZC1,结合菌落特征和16S r DNA序列对其进行鉴定,将该菌在含Cd2+液体LB培养基中进行连续培养,获得菌体生长情况,分析该菌株镉耐性是否与质粒相关,检测菌株对其他几种重金属的耐性。结果表明,该菌株是Pseudomonas sp.,在Cd2+浓度为400mg/L LB培养基中可正常生长;经过质粒消除的XZC1不具有镉耐性,说明该菌株的镉耐性基因存在于大质粒上;XZC1对Fe2+、Cu2+、Mn2+、Ni2+的耐性较强,在400mg/L以上。菌株XZC1在重金属污染防治方面有深入研究价值。      

3SPS+1PS型并联机器人动态静力分析向量键合图法

为提高复杂空间机器人系统动态静力分析的效率及可靠性,提出了相应的向量键合图法。根据运动约束条件,建立了空间球铰及棱柱铰的向量键合图模型。在此基础上,建立了3SPS+1PS型并联机器人向量键合图模型。针对微分因果关系及非线性结型结构给空间机器人机构自动建模与动态静力分析所带来的代数困难,提出了有效的增广方法。应用相应的算法,实现了3SPS+1PS型并联机器人系统计算机自动建模与动态静力分析,由此说明了所述方法的有效性。