A conjugate gradient-based algorithm to minimize the sidelobe levelof planar arrays with element failures

Element failures increase the sidelobe power level of an array. Reconfiguring the amplitude and phase distribution of the remaining elements can partially compensate for the failed elements and thus reduce the sidelobe level. An algorithm is obtained that yields the reconfigured distribution by minimizing the ratio of the average peak sidelobe power level to the power in the main beam, taking into account the defective elements. The minimization of this nonlinear function is carried out via a conjugate gradient method. The algorithm is applied to the synthesis of sum and difference patterns of planar arrays     

缺陷问题驱动浸没光刻技术发展

涂层的应用导致晶圆上缺陷的增加或者使光刻表现发生变化虽然现在推测浸没光刻技术的量产时间还太早,但是许多公司正在努力确定生产线何时能从干法工艺跃为湿法工艺。根据最近在San Jose举办的     

A physically based approach to granular media mechanics: grain-scale experiments,initial results and implications to numerical modeling

It is generally appreciated that the mechanical behavior of granular media depends fundamentally on the interaction of the constituent particles, and that the validity of numerical models of granular media would be greatly improved with knowledge of the grain-scale mechanics. However, most supporting experimental work has been conducted on highly idealized materials, and a limited amount of information exists on grain-scale force–displacement relationships for naturally occurring materials. To address this shortcoming, we are conducting a program that integrates laboratory experiments on grains of naturally occurring aggregate with the discrete element modeling method, with the goal of relating the grain-scale physical and mechanical properties of granular media to bulk behavior. The paper describes the equipment and methods that have been developed to conduct close-loop controlled, grain-scale experiments under monotonic and cyclic loading conditions, and presents results from an initial set of experiments on unbonded grains. The implications of the grain-scale results to the discrete element model are discussed. Discussions center on the applicability of a physically based approach to the mechanics of granular media in general. In light of future exploration missions and the resulting need to predict the mechanical properties of lunar and planetary regoliths, the paper examines the potential usefulness of our physically based approach to the problem of predicting the behavior of the types of materials found in those environments.     

成品率的预测准确度有多高

成品率预测是可制造性设计（DFM）的基础之，但它还远不止于此。IBM系统和技术群300mm半导体运营副总裁DanArmbrust说：“我们精确预测成品率的能力就是我们的经济模式。”Armbrust是SEMICON West 2007成品率论坛讨论DFM现状的三位参与者之一。与他共同参加讨论的是Synopsys公司DFM解决方案副总裁Anantha Sethuraman和Photronics公司的CTO Chris Progler。     

Kinetik der polykondensation von natriumsulfidhydrat und 1,4-dichlorbenzol zu poly(thio-1,4-phenylen)

The kinetics of the polycondensation of sodium sulfide hydrate and 1,4-dichlorobenzene to poly(thio-1,4-phenylene) in 1-methyl-2-pyrrolidone as solvent was studied in a differential scanning calorimeter at temperatures between 220 and 280°C. This polycondensation shows an autocatalytic behavior and the kinetics can be modelled by a first order reaction up to complete conversion. This is explained by the low solubility of sodium sulfide in l-methyl-2-pyrrolidone. The concentration of sodium sulfide is regarded as being constant during the whole course of the reaction. The autocatalytic effect can be explained by the increase of the condensation rate constant at the beginning of polycondensation due to the higher reactivity of the oligomers compared to the monomers. The number- and the weight-average molecular weight of the products formed during the course of the polycondensation can be modelled by means of stochastic methods. A simple model with only two different rate constants of the condensation process is assumed. The concentration of sodium sulfide in the reactive phase is found to be 2–5% of the value of dichlorobenzene at the beginning of the reaction and remains constant nearly until the end of polycondensation.     

Abrupt (< 1 day), acute (< 1 week), and early (< 1 month) vessel closure at the angioplasty site. Morphologic observations and causes of closure in 130 necropsy patients undergoing coronary angioplasty

While abundant clinical and angiographic data are available regarding features of acute or abrupt closure at the site of balloon angioplasty, little morphologic information is available. This study discusses morphologic-histologic causes for acute closure after angioplasty in 130 necropsy patients. Intimal-medial flaps, elastic recoil, and primary thrombosis were the three leading morphologic causes for closure. Data were subdivided into time categories: abrupt (< 1 day), acute (< 1 week), and early (< 1 month). Intimal-medial flaps remained the most common cause for angioplasty closure despite time from angioplasty to documented occlusion. Morphologic recognition of types and frequencies of angioplasty closure are discussed, and specific mechanical, pharmacologic, or combined treatments are reviewed.     

A Study of Surface Deformation during Wire‐Rod Rolling of High Speed Steels using Experimental and Computational Techniques

The evolution of surface defects during shape rolling of high‐speed steel billets is studied using longitudinal surface defects prepared by machining and welding. The reduction of the defects during rolling in a production mill is compared to the total area reduction of the billets. Samples are collected after pass 4, 6, 8, 14, 19 and the final pass, 28, representing the finished 5.5mm wire. By inspecting the cross sections, the rotation of the billets from pass to pass is evaluated. Results from FE simulations on solid billets are compared to the experimental results. Generally, simulations predict less reduction than observed experimentally. In most cases cracks reduce most effectively followed by carbon steel welds and stainless steel welds.