Application of asymptotic waveform evaluation to eigenmode expansion method for analysis of simultaneous switching noise in printed circuit boards (PCBs)

In this paper, the asymptotic waveform evaluation (AWE) technique is first applied to the conventional eigenmode expansion method for characterizing a power/ground (P/G) plane pair and analyzing the simultaneous switching noise on such plane pairs for printed circuit boards or multichip modules. The application of AWE avoids a large number of iterations in computing the impedance frequency response of a P/G plane pair structure and greatly reduces the computation time. Meanwhile, to obtain an accurate solution in an entire frequency range, we employ the complex frequency hopping technique which can help select multiple expansion points. In addition, the proposed approach can also be used to characterize the P/G plane pair structures with irregular shapes. Three examples demonstrate its high efficiency and good accuracy.     

宣汉——达县地区飞仙关组储层预测方法研究

在宣汉-达县地区,以往仅依据地震属性来预测飞仙关组储层分布,钻探结果与实际情况不符,为此本文提出量化分析预测结合主参数分析的新方法和新思路。在量化分析中首先对飞仙关组储层进行高分辨率反演,获得储能系数图;然后结合主振幅剖面和主频率剖面分析,对储层进行预测。在研究区,本方法的预测结果与实钻情况相吻合。     

乙苯/苯乙烯塔分离效率问题的技术分析及整改措施

分析了齐鲁分公司200kt/a乙苯/苯乙烯装置乙苯/苯乙烯塔(T-401)分离效率低的原因,即降液管设计偏小,液体在降液管内流速过快,引起液体飞溅;安装分布器使用的石棉垫片溶胀而粉碎后堵塞了分布槽;分布器上使用的垫片脱落形成缝隙而漏液;填料装得不密实,留有缝隙;二级分布槽变形等.针对存在问题提出了相应的整改措施,并考察了整改措施实施效果.结果表明,整改后该塔的分离能力满足了工艺要求,并有一定的操作弹性.     

企业信息化

主要介绍企业信息化的定义、内涵、外延、分类、层次及意义，并根据国内企业信息化建设的经验教训，提出了几点值得重视的建议。     

α-Fe_2O_3(SO_4~(2-),Sn)气敏电阻的温度响应特性

在气敏温度区域内研究了α-Fe_2O_3(SO_4~(2-),Sn)材料的电阻-温度特性,认为表面结构的变化导致温度特性出现峰值并呈现气敏性。可利用空气中电阻温度特性提供的信息改性或发现新的气敏材料。     

Efficiency improvement of near-ultraviolet InGaN LEDs using patterned sapphire substrates

The use of conventional and patterned sapphire substrates (PSSs) to fabricate InGaN-based near-ultraviolet (410 nm) light-emitting diodes (LEDs) was demonstrated. The PSS was prepared using a periodic hole pattern (diameter: 3 /spl mu/m; spacing: 3 /spl mu/m) on the (0001) sapphire with different etching depths. From transmission-electron-microscopy and etch-pit-density studies, the PSS with an optimum pattern depth (D/sub h/=1.5 /spl mu/m) was confirmed to be an efficient way to reduce the thread dislocations in the GaN microstructure. It was found that the output power increased from 8.6 to 10.4 mW, corresponding to about 29% increases in the external quantum efficiency. However, the internal quantum efficiency (@ 20 mA) was about 36% and 38% for the conventional and PSS LEDs, respectively. The achieved improvement of the output power is not only due to the improvement of the internal quantum efficiency upon decreasing the dislocation density, but also due to the enhancement of the extraction efficiency using the PSS. Finally, better long-time reliability of the PSS LED performance was observed.     

Scattering of plane SH-waves by a cylindrical canyon of arbitrary shape in anisotropic media

The scattering and diffraction of plane SH-waves, by an arbitrary-shaped cylindrical canyon in anisotropic media is formulated here. Analytical solutions are obtained via the complex function theory, using the orthogonal property of the Hermite functions to solve the resulting set of infinite algebraic equations. Expressions for scattered displacements and scattered stresses are given. Three cross-sectional profile types are used in the numerical simulation of the two-dimensional canyon topography: (a) a semi-circular profile, (b) a semi-elliptical profile and (c) a triangular profile. The results obtained in (a) and (b) are consistent with known solutions computed by Trifunac and his co-workers [1,3] using a different method. As the exact solution for (c) is not known to exist, the result given here is believed to be new and would therefore serve as a useful check for numerical analysts working in this area.     

М.Ю.巴利新的粉末冶金理论

巴利新(原苏联)是世界知名的粉末冶金学家。1938年他提出的压制方程ln p=—AV+B仍为美国1984年出版的《金属手册》第九版第七卷‘粉末冶金’所引用。早在70年代,巴利新就根据他提出的一系列新理论,提出一个新的压制或固结方程式组α=~2z,f=F(,α),p=pαf,但除原苏联外,该方程鲜为人知。鉴于此,本文作者对巴利新60年代以来发表的一系列关于粉末冶金理论的论著进行了整理,现扼要地予以阐述,这对我国粉末冶金理论的研究或许是有益的。