强冷空气影响下的强对流天气对比分析

2007年5月和2006年6月两次相似的强对流天气给浙江省带来了强烈的雷雨大风和短时冰雹天气,这两次过程最主要的特征表现在中高层蕴含深厚的冷空气条件,而低层存在浅薄的暖湿气流.综合运用雷达卫星及NCEP实况资料,对比分析了强对流发生发展的环境条件、云图及回波特征,进而揭示出此类天气的主要特点和可预报性.分析发现,925 hPa的切变线形成中尺度触发机制,对预报雷暴的发展走向具有不可忽视的作用;冷空气南下造成的冷暖平流交汇是触发对流的主要原因;云图上,云系移动前方形成较大的亮温梯度,后方形成干涌边界;雷达回波中表现出阵风锋的影响,这些都是地面灾害性大风产生的主要征兆.另外,强回波对应较大的风向切变区和悬挂回波是冰雹产生的重要特征.     

An Efficient Algorithm for Obtaining the Optimum Solution of a Generalized Assignment Problem

１　ＩｎｔｒｏｄｕｃｔｉｏｎＡｓｓｉｇｎｍｅｎｔｐｒｏｂｌｅｍｉｓｏｎｅｏｆｔｈｅｍｏｓｔｆａｍｏｕｓｏｐｅｒａｔｉｏｎａｌｒｅｓｅａｒｃｈｐｒｏｂｌｅｍ,ｗｈｉｃｈｈａｓｗｉｄｅｓｐｒｅａｄａｐｐｌｉｃａｔｉｏｎｉｎｐｒａｃｔｉｃａｌｍａｎａｇｅｍｅｎｔａｎｄｄｅｃｉｓｉｏｎｍａｋｉｎｇｐｒｏｂｌｅｍ．Ｐａｐｅｒ［１］ｐｒｅｓｅｎｔｅｄａｍｏｒｅｇｅｎｅｒａｌａｓｓｉｇｎｍｅｎｔｐｒｏｂｌｅｍｏｎｔｈｅｂａｓｉｓｏｆｔｒａｄｉｔｉｏｎａｌｏｎｅ［２］．Ａｃｃｏｒｄｉｎｇｔｏｔｈｅｐｒａｃｔｉｃ…     

Digital Jacquard Fabric Design in Colorful Mode

IntroductionNowadaystheJacquardmachinehasbeendevelopedintoanelectronicformwithcomputercontrol,andNetcommunicationiswidelyusedinJacquardweavingsheds.Ontheotherhand ,theJacquardtextileCADsystemdevel opedquicklyasaresultoftheadvanceincomputertech nology .TheadvanceofJacquardtextileCADischangingthemethodofJacquardtextiledesign ,andguidingthenewconceptofJacquardfabricdesign ,whichfollowsthedirec tionofresearchondigitaltextile[1] .Inaddition ,thescienceofdigitaltechnologybasedonthebinarysystem…     

A New Network Planning Method Based on the Connection Number a bi of SPA

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｔｉｍｅｌｉｍｉｔｉｎｆｏｒｍａｔｉｏｎｏｆａｗｏｒｋｉｎｇｐｒｏｃｅｄｕｒｅｉｎａｌａｒｇｅ ｓｃａｌｅｐｒｏｊｅｃｔｉｓｕｓｕａｌｌｙｕｎｃｅｒｔａｉｎ ,ｂｅｃａｕｓｅｏｆｓｏｍｅｕｎｃｅｒｔａｉｎｆａｃｔｏｒｓｅｘｉｔｉｎｇ .Ｐａｐｅｒｓ [1 ,2 ]ｏｎｌｙｒｅｇａｒｄｔｈｉｓｕｎｃｅｒｔａｉｎｔｙａｓｆａｚｚｙｕｎｃｅｒｔａｉｎｔｙ ,ｔｈｅｙｕｓｅｆｕｚｚｙｎｕｍｂｅｒｓｔｏｅｘｐｒｅｓｓｔｈｅｔｉｍｅｌｉｍｉｔｏｆｅａｃｈｗｏｒｋｉｎｇｐｒｏｃｅｄｕｒｅａｎ…     

电网参量的无纸记录仪

介绍了一种新型的三相电参量无纸记录仪，该记录仪采用复序列FFT变换算法对电网谐波的电流、电压、有功功率、无功功率和功率因数进行计算、分析、显示．记录仪在硬件上以TI公司的DSP芯片TMS320LF2407为核心处理器；在软件上以实时多任务操作系统μC／OS-Ⅱ为系统运行的软件平台，使系统具有很好的实时性、稳定性、可靠性。     

An Optimization Design of a Weft Insertion Mechanism for Rapier Looms

By analyzing a combined and spatial 6-bar linkage weft insertion mechanism, its practical model for optimization design is set up and the modification of penalty strategy is put forward so that the genetic algorithm can be better used in optimization design for mechanisms with non-linear constraints. The design result is discussed.     

Fashion CAD Based on Draping Knowledge

A computer-aided design system, which is base on the knowledge of draping and frame-producer methods, is put forward. All kinds of knowledge applied here are abstracted from fashion design, where a complicate object is divided into several simple parts according to the body parts. And then a mathematical model of the display for real fashion illustration is elucidated.     

Investigation of the Reaction Mechanism of Itaconic Acid/Maleic Acid Copolymer System and Cotton Cellulose

The reaction mechanism of IA/MA copolymer system andcotton cellulose is conjectured and verified, the two keysteps, such as the formation of cyclic anhydride interme-diates and the building of ester crosslinklng, and the ef-fect of sodium hypophosphite are especially emphasized,by FT - IR spectroscopy and acid- base titration anal-yses. The experiments reveal that carboxylic acids main.ly change to cyclic anhydride in the pre - drying step andSodium Hypophosphite (SHP) has effect on it, but mostester - crosslinkages are built in the curing step and SHPhas effects on both anhydride formation and ester -crosslinking formation.     

Equilibrium equations for nonlinear buckling analysis of drill-strings in 3D curved well-bores

With the development of drilling technology,the oil/gas well has evolved from its early vertical straight form to the inclined,horizontal,plane curved,or even 3D curved well-bore.Understanding of the buckling behavior of a drill-string in a well-bore is crucial for the success of a drilling operation.Therefore,equilibrium equations for analyzing the buckling behavior of a drill-string in a 3D curved well-bore are required.Based on Love's equilibrium equations for a curved and twisted rod in space,a set of e...     

Modeling large reversible electric-field-induced strain in ferroelectric materials using 90° orientation switching

Reversible large electric-field-induced strain caused by reversible orientation switchings in BaTiO3 is modeled using the Landau's theory of phase transition.A triple well free energy function is constructed.Each of its minima is associated with one of the polarization orientations involved.Nonlinear constitutive laws accounting for reversible orientation switchings and electrostriction effects are obtained by using thermodynamic equilibrium conditions.Hysteretic dynamics of onedimensional structures is des...