雷电电磁脉冲对架空电力线的耦合效应

 从传输线模型出发,通过建立雷电回击通道、大地和电力线系统一体化模型,采用时域有限差分法计算得出雷电回击电流的近场分布,将场值代入离散的传输线方程后,计算了架空电力线终端的感应过电压。通过对多导体架空线和单导体线终端感应过电压的分析,发现由于其它导体的存在,多导体系统中单根导体两端的感应电压峰值比相同高度处单一导体两端的感应电压峰值低10%～20%;并且对于垂直导体结构,最小感应电压产生在距离地面最近的导体上;而对于水平导体结构,最小感应电压产生在中间导体上。     

回旋速调管调制腔模拟分析

 多腔回旋速调管中的调制腔采用内外腔同轴结构,对回旋电子注角向群聚起着关键作用。用场匹配理论及HFSS软件对调制腔冷腔特性进行了研究,对多种输入结构、耦合缝尺寸和方位、腔体长度、半径进行了模拟。分析表明,耦合狭缝中心线与输入波导轴线成45°,耦合缝长度达到0.72时,内外腔储能比值达到41.65;耦合缝尺寸对腔体Q值影响较大,但并非呈简单线性关系,并且Q值对缝长的变化比缝宽的变化要敏感得多;而狭缝尺寸变化对谐振频率的影响不大;计算了内外腔储能,得到了模式转换效率高、内外腔储能比高、性能优良的调制腔。     

Many-body work distributions

The work distribution function for a non-relativistic, non-interacting quantum many-body system interacting with classical external sources is investigated. Exact expressions for the characteristic function corresponding to the work distribution function is obtained for arbitrary switching function and coupling functions. The many-body frequencies are assumed to be generally time-dependent in order to take into account the possibility of moving the boundaries of the system in a predefined process linking the characteristic function to the fluctuation-induced energies in confined geometries. Some limiting cases are considered and discussed.     

The use of non-cavitating coupling fluids for intensifying sonoelectrochemical processes

For the first time, we have investigated the beneficial effects of non-cavitating coupling fluids and their moderate overpressures in enhancing mass-transfer and acoustic energy transfer in a double cell micro-sonoreactor. Silicon and engine oils of different viscosities were used as non-cavitating coupling fluids. A formulated monoethylene glycol (FMG), which is a regular cooling fluid, was also used as reference. It was found that silicon oil yielded a maximum acoustic energy transfer (3.05 W/cm²) from the double jacketed cell to the inner cell volume, at 1 bar of coupling fluid overpressure which was 2.5 times higher than the regular FMG cooling fluid. It was also found that the low viscosity engine oil had a higher acoustic energy value than that of the high viscosity engine oil. In addition, linear sweep voltammograms (LSV) were recorded for the quasi-reversible Fe^2+/Fe³⁺ redox couple (equimolar, 5 × 10⁻³ M) on a Pt electrode in order to determine the mass-transport limited current density (j_lim) and the dimensionless Sherwood number (Sh). From the LSV data, a statistical analysis was performed in order to determine the contribution of acoustic cavitation in the current density variation |Δj|_average. It was found that silicon oil at 1 bar exhibited a maximum current density variation, |Δj|_average of ~2 mA/cm² whereas in the absence of overpressure, the high viscosity engine oil led to a maximum |Δj|_average which decreased gradually with increasing coupling fluid overpressure. High viscosity engine oil gave a maximum Sh number even without any overpressure which decreased gradually with increasing overpressure. The Sh number for silicon oil increased with increasing overpressure and reached a maximum at 1 bar of overpressure. For any sonoelectrochemical processes, if the aim is to achieve high mass-transfer and acoustic energy transfer, then silicon oil at 1 bar of overpressure is a suitable candidate to be used as a coupling fluid.     

超声条件下合成4—戊基（4‘—丙基）双环己基联苯

在超声辐射下,用相转移催化剂十六烷基三甲基溴化铵作助催化剂,室温下通过氯化钯催化４－（４’－丙基）环己基苯基硼酸与４－（４’－戊基）环己基溴苯偶联反应２０ｍｉｎ,合成了４－戊基（４’－丙基）双环己基联苯,反应转化率９７％,反式产物选择性６２％。     

Chiral Steroidal Phosphines: Synthesis and Platinum Complexes

Summary.  The synthesis of novel 3- and 17-diphenylphosphino-androstane derivatives via homogeneous catalytic P-C coupling is described. The products were characterized by ¹H and ³¹P NMR measurements. According to the NMR investigation of the PtCl₂P₂-type complexes, the steroidal phosphines are trans-coordinated with respect to the Pt-centre exclusively. Received June 14, 2000. Accepted (revised) July 24, 2000     

Bithienylsilanes: unexpected structure and reactivity

5-(2,2′-Bithienyl)hydrosilanes were prepared by reaction of bithienyl lithium with chlorodimethylsilane, dichloromethylsilane and trichlorosilane. It was shown that 5-(2,2′-bithienyl)dimethylsilane possesses higher reactivity in the hydrosilylation reaction of monosubstituted acetylene derivatives compared with (2-thienyl)dimethylsilane. The elongation of the π-conjugated chain leads to increasing selectivity of the hydrosilylation reaction. An unusual structure for bis[5-(2,2′-bithienyl)]methylsilane has been established by X-ray analysis.     

最高量子相关谱技术在同核偶合常数测定中的应用(英文)

偶合常数是一个重要的NMR参数,其数值与分子中化学键的二面角有关,可以为分子结构研究提供很重要的信息.多维NMR谱由于具有较大的化学位移分辨率,因此常常被用来测定同核或异核自旋-自旋偶合常数.本文介绍了利用最高量子相关技术(MAXY)测定同核偶合常数的方法.MAXY是最近发展的一种多维NMR谱编辑技术,可以使不同官能团(CH,CH₂,CH₃)的相关峰分布于不同的图谱区域,因此比常规的二维谱具有更高的化学位移分辨率.而且被分离开来的NMR相关峰呈吸收性线型,能清楚地展示各自的偶合分裂特征,可以直接用于测定偶合常数.     

光纤光栅环形腔激光器的输出特性研究

研究了光纤光栅环形腔激光器的输出耦合比与输出功率之间的关系,实验结果表明最佳输出耦合比约位于80%～90%理论分析了不同腔内损耗情况下的输出特性,数值模拟结果与实验能较好地吻合.