横观各向同性压电空间中圆裂纹与合成点源的三维相互作用

研究了横观各向同性压电空间中的圆裂纹与包括力偶极子、电偶极子、点力矩、力张和力旋这些常见合成点源的相互作用．用初等函数的形式给出了在任意位置和方向的合成点源作用下,裂纹尖端3种应力强度因子和电位移强度因子的三维解．其中圆裂纹包括币形裂纹和外圆裂纹．这一系列的力电合成点源不仅其自身在工程中普遍存在,而且在某些情形下还可以模拟诸如微裂纹、空洞、夹杂和位错等缺陷．     

医药类专业物理课程教学存在的问题及对策

根据对国内69所普通高等院校医药类专业（本科）物理课程教学现状调查的结果,分析了在我国高等教育进入“大众化教育”的形势下,医药类专业物理课程教学中存在的4个急需解决的问题,指出了医药类专业物理课程教学改革的方向,并介绍了我们所做的一些工作。     

Performance analysis of automatic assembly systems with in-line parallel stations

An automatic assembly system—a key tool for mass production—isgenerally composed of a number of workstations and a transportsystem. One common problem associated with automatic assemblysystems is that some assembly operations may have relativelylong cycle times. As a consequence, productivity, which is determinedby the operations with the longest cycle time, can be reducedsignificantly. Therefore a special form of parallel workstationknown as an in-line parallel (tandem-gated) station was developedto improve the performance of an automatic assembly system.In this design, stations working in parallel are installed ina serial structure and perform identical operations. Thus, morethan one assembly may be processed simultaneously—a typeof design especially beneficial when a stage requires a longoperation cycle time. A typical example is a computer assemblysystem which performs long inspection operations to ensure thatthe quality level of each product is up to the acceptance level. In this paper, we describe a simulation study of the performancecharacteristics of this type of system, with a statistical analysisof each decision factor. Phenomena affecting the performanceof in-line parallel stations, identified by the assistance ofthe computer graphical display, will then be discussed. An analyticalmodel based on these phenomena identified is then developed.The results generated by the analytical model developed arevalidated by comparisons with the simulation results. Finally,guidelines for optimization of buffer size are presented.     

归头和归尾二维相关红外光谱法的鉴别研究

采用红外光谱法 (FourierTransformInfraredSpectroscopy ,FTIR)并结合二维相关 (Two dimensionalcorrelationspectroscopy)分析技术分析鉴别了来自甘肃岷县的两批当归药材各自的归头和归尾。尽管归头和归尾属于同种药材的不同药用部位 ,在红外的一维谱图上较为相似 ,但由于氨基酸和挥发油在当归的根头部分和归尾部分的分布不均一而引起二维相关红外谱的不同而可方便的加以区分鉴别。该法快速、准确 ,为客观评价中药材提供了一种新的方法和手段