automated test program generation for an industrial optimizing compiler

Association for Computing Machinery, ACM; IEEE; IEEE Computer Society; SIGSOFT

Effects of Thermocapillary Convection on the Growth Process in Industrial 8-inch Silicon Czochralski Growth

Czochralski (CZ) crystal growth process is a widely used technique in manufacturing of silicon crystals and other semiconductor materials. The ultimate goal of the IC industry is to have the highest quality substrates, which are free of point defect, impurities and micro defect clusters. The scale up of silicon wafer size from 200 mm to 300 mm requires large crucible size and more heat power. Transport phenomena in crystal growth processes are quite complex due to melt and gas flows that may be oscillatory and/or turbulent, coupled convection and radiation, impurities and dopant distributions, unsteady kinetics of the growth process, melt crystal interface dynamics, free surface and meniscus, stoichiometry in the case of compound materials. A global model has been developed to simulate the temperature distribution and melt flow in an 8-inch system. The present program features the fluid convection, magnetohydrodynamics, and radiation models. A multi-zone method is used to divide the Cz system into different zones, e.g., the melt, the crystal and the hot zone. For calculation of temperature distribution, the whole system inside the stainless chamber is considered. For the convective flow, only the melt is considered. The widely used zonal method divides the surface of the radiation enclosure into a number of zones, which has a uniform distribution of temperature, radiative properties and composition. The integro-differential equations for the radiative heat transfer are solved using the matrix inversion technique. The zonal method for radiative heat transfer is used in the growth chamber, which is confined by crystal surface, melt surface, heat shield, and pull chamber. Free surface and crystal/melt interface are tracked using adaptive grid generation. The competition between the thermocapillary convection induced by non-uniform temperature distributions on the free surface and the forced convection by the rotation of the crystal determines the interface shape, dopant distribution, and striation pattern. The temperature gradients on the free surface are influenced by the effects of the thermocapillary force on the free surface and the rotation of the crystal and the crucible.

Prescription for optimizing holograms in LiNbO3 : Fe : Mn

The photorefractive holographic dynamics of grating formation in photochromic doubly doped LiNbO3:Fe:Mn crystal is studied numerically and analytically in terms of the two-center model of Kukhtarev Et al. [Ferroelectrics 22, 949 (1979)]. The relations among the recorded and fixed space-charge fields and the doping densities, the oxidation-reduction states of the fields, and the intensities of UV-sensitizing and red recording beams are studied. Important conditions and effects are feued, and an optimal prescription for material doping and oxidation-reduction processing is suggested in which the crystal can be strongly oxidized and the Mn-doping density is smaller than the Fe-doping density. (C) 2000 Optical Society of America. OCIS codes: 050.7330, 190.5330, 090.2900.

Effects of micronutrients on biological treatment efficiency of textile wastewater

Micronutrients play a very important role in biological processes for wastewater treatment. Many industrial wastewaters lack in nutrients (macronutrients and micronutrients) required for microbial growth, and this is one of the main problems at many activated sludge plants treating industrial wastewater. The microbial community structure is one of the important factors controlling the pollutant-degrading capacity of biological wastewater treatment system. In this study, the concentrations of micronutrients of the textile wastewater discharged from a textile plant were determined, and the effects of micronutrients on treatment efficiency and microorganism community structure of the biological treatment system were studied. The results showed that the optimal concentrations of magnesium, molybdenum, zinc, thiamine and niacin in the textile wastewater were 5.0, 2.0, 1.0, 1.0 and 1.0mg/L, respectively. The COD removal rates when magnesium, molybdenum, zinc, thiamine and niacin were added individually to the wastewater in their optimal concentrations were 1.8, 1.4, 1.3, 1.6 and 2.2 times of that of the control, respectively. The improving effects of combinations of zinc and thiamine, zinc and niacin, thiamine and niacin were better than single micronutrient. The diversity of quinones (DQ) changed significantly after the micronutrient was added into the wastewater treatment system. This indicated that there was probably a feasibility of optimizing the biological treatment performances and microorganism community structure of textile wastewater treatment system through micronutrient supplement.

Optimizing the GaAs capping layer growth of 1.3 mu m InAs/GaAs quantum dots by a combined two-temperature and annealing process at low temperatures

We report on optimizing the GaAs capping layer growth of 1.3 mu m InAs quantum dots (QDs) by a combined two-temperature and annealing process at low temperatures using metalorganic chemical vapor deposition. The initial part (tnm) of the capping layer is deposited at a low temperature of 500 degrees C, which is the same for the growth of both the QDs and a 5-nm-thick In0.15Ga0.85As strain-reducing capping layer on the QDs, while the remaining part is grown at a higher temperature of 560 degrees C after a rapid temperature rise and subsequent annealing period at this temperature. The capping layer is deposited at the low temperatures (<= 560 degrees C) to avoid postgrowth annealing effect that can blueshift the emission wavelength of the QDs. We demonstrate the existence of an optimum t (=5 nm) and a critical annealing time (>= 450s) during the capping, resulting in significantly enhanced photoluminescence from the QDs. This significant enhancement in photoluminescence is attributed to a dramatic reduction of defects due to the optimized capping growth. The technique reported here has important implications for realizing stacked 1.3 mu m InAs/GaAs QD lasers. (C) 2008 Elsevier B.V. All rights reserved.

Processing network models of energy/environment systems

Processing networks are a variant of the standard linear programming network model which are especially useful for optimizing industrial energy/environment systems. Modelling advantages include an intuitive diagrammatic representation and the ability to incorporate all forms of energy and pollutants in a single integrated linear network model. Added advantages include increased speed of solution and algorithms supporting formulation. The paper explores their use in modelling the energy and pollution control systems in large industrial plants. The pollution control options in an ethylene production plant are analyzed as an example. PROFLOW, a computer tool for the formulation, analysis, and solution of processing network models, is introduced.

基于形式描述的编译优化自动测试方法与技术研究

编译优化是现代编译器不可缺少的重要功能。编译优化技术在过去几十年里取得了显著进展，对提升程序运行速度、节省存储空间、节省能耗等起到了不可替代的作用。然而，编译优化的可靠性却不尽人意。编译优化技术种类多、处理复杂而且可复用性弱，容易出错，即便是成熟的编译器，也不断有与编译优化相关的bug被发现出来。编译器的可靠性对软件产品的可靠性和安全性有直接影响，随着编译优化在现代编译器中的比重不断增加，编译优化的可靠性也日益受到人们的关注。 软件测试是保障编译优化可靠性的基本技术手段之一，然而，编译优化测试涉及测试程序编写、测试执行等过程，人工完成相当费时费力，因此有必要研究编译优化自动测试方法，以提高编译优化测试的效率。基于这一实际需求，Intel、MEI (Matsushita Electric Industrial)、DaimlerChrysler AG等业界产商近年来也相继与有关研究机构开展合作，研究编译优化自动测试方法。 目前已有的编译器自动测试方法中大多数都是以程序设计语言的语法和语义为主要依据，适用于测试语法检查、语义检查、代码生成等基本编译功能，对于编译优化的测试则缺乏针对性，测试效率较低，而已有的若干种面向编译优化的自动测试方法也存在着对编译优化刻画不够准确、自动化程度不高等缺陷。 本文提出一种基于形式描述的编译优化自动测试方法(TEMCOFS)，其实现过程分为四个阶段，即：(1) 建立编译优化形式描述；(2) 分析编译优化描述的正确性；(3) 基于编译优化形式描述自动生成测试程序；(4) 自动执行测试。在TEMCOFS方法框架下，本文分别研究了编译优化形式化描述方法、编译优化描述正确性分析方法和基于形式描述的两种自动测试方法，实现了三类典型优化—表达式优化、数据流优化、循环优化的自动测试，主要工作包括： (1) 在编译优化形式描述方面，除了应用前人研究成果—TRANS语言描述了表达式优化和数据流优化之外，还对TRANS语言进行了扩展，建立了循环优化的形式描述机制； (2) 在编译优化正确性分析方面，首先证明了揭示程序数据依赖关系对程序变换正确性影响的依赖基础定理，为循环优化正确性分析提供了基础，然后探讨了编译优化正确性分析的一般方法； (3) 在测试自动执行方面，提出了编译优化自动变形测试执行方法，该方法将变形测试思想引入编译优化测试中，利用测试程序等价性质实现测试结果的自动判定，能够避免传统方法中测试结果判定所存在的问题； (4) 在测试程序自动生成方面，分别对应两种测试自动执行方法—比照法和变形法提出了基于编译优化形式描述的测试程序自动生成方法，能够根据表达式优化、数据流优化、循环优化的形式描述自动生成测试程序集。 在GCC编译器上的实验表明，基于本文方法自动生成的测试程序集可使GCC的编译优化模块较快达到较高的测试覆盖率。与其他编译器自动测试方法相比，本文方法对编译优化测试的针对性较好，自动化程度也较高。总而言之，本文方法对于提高编译优化测试效率、保障优化编译器的质量具有较好的实用和参考价值。

Modeling and optimizing of high-concentration erbium-doped fiber amplifiers with consideration of ion-clusters

Starting from the modeling of isolated ions and ion-clusters, a closed form rate and power evolution equations for high-concentration erbium-doped fiber amplifiers are constructed. Based on the equations, the effects of the fraction of ion-clusters in total ions and the number of ions per cluster on the performance of high-concentration erbium-doped fiber amplifiers are analyzed numerically. The results show that the presence of the ion-clusters deteriorates amplifier performance, such as the signal power, signal gain, the threshold pump power for zero gain, saturated signal gain, and the maximum gain efficiency, etc. The optimum fiber length or other parameters should be modified with the ion-clusters being taken into account for the amplifiers to achieve a better performance. (c) 2007 Elsevier B.V. All rights reserved.