Fluid Flow Modeling of Arc Plasma and Bath Circulation in DC Electric Arc Furnace

 A mathematical model describing the flow field, heat transfer and the electromagnetic phenomenon in a DC electric arc furnace has been developed. First the governing equations in the arc plasma region are solved and the calculated results of heat transfer, current density and shear stresses on the anode surface are used as boundary conditions in a model of molten bath. Then a two dimensional time dependent model is used to describe the flow field and electromagnetic phenomenon in the molten bath. Moreover, the effect of bottom electrode diameter on the circulation of molten bath is studied.     

Flow stress behavior of Cu13Zn alloy deformed at elevated temperature

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弛豫型铁电体PZNT制备与性能研究的进展

本文综述了近年来国际上弛豫型铁电体PZNT的制备与介电、压电及电致伸缩性能研究的进展．PZNT单晶体的制备方法以高温PbO熔剂法为主,其尺寸已达40mm．随PT含量的变化,PZNT的顺电一铁电相交由弥散性、混合型变为一级相变;其铁电-铁电相变可由组份或电场诱导,由介电性能表征．压电性能在MPB处及偏向三方相一侧达到最佳,＜001＞切向的三方相与四方相单晶可分别作为频带宽、分辨率高、且阻抗匹配好的新一代声阵列与单个器件传感器．＜001＞向的PZNT单晶具有巨大的电致伸缩应变,可望成为高性能的固体驱动器．     

A NEW APPROACH TO MODELING OF TRAFFIC FLOW IN CITIES

Based on the properties of traffic,macroscopic dynamic equations are set up to simulate the flow of traffic. Besides relaxation term and compressibility term, a changeable area term is composed in the model to describe the effect of car parking,tollbooth,traffic incidents,road grading and bicycles on traffic flow.With numerical method, three cases are presented to simulate the changing lane area with time and space and the propagating process of high traffic density. The results show that the dynamic model can reasonably describe the evolution of traffic states in various complicated occasions.     

四方相铌镁酸铅-钛酸铅(PMN-PT)铁电单晶的弹性、介电、压电和机电性能

研究了四方相弛豫铁电单晶Pb(Mg1/3Nb2/3)O3-38%PbTiO3(PMNT62/38)的介温特性，并利用HP4192A阻抗分析仪测量了PMNT62/38单晶完整的一套弹性、介电、压电和机电耦合系数，为理论研究和器件设计提供了参考，其居里点Tc-174℃；压电应变常量d33-300pC/N；介电常数ε33-734,ε11-4301；机电耦合因数κ33-84.6%,κt-60.8%,κ31-44.5%,κ15-45.9%。     

Dynamic Optimal Design for the Reliability of a Mechanical System

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Effects of AlMnCa and AlMnFe Alloys on Deoxidization of Low Carbon and Low SiliconAluminum Killed Steels

To confirm the effects of AlMnCa and AlMnFe alloys on the deoxidization and modification of Al2O3 inclusions, experiments of 4heat low carbon and low siliconaluminum killed steels deoxidized by AlMnCa and AlMnFe alloys were done in a MoSi2 furnace at 1 873 K. It is found that the 1# AlMnCa alloy has the best ability of deoxidization and modification of Al2O3 inclusions than 2# AlMnCa and AlMnFe alloys. Steel A deoxidized by 1# AlMnCa alloy has the lowest total oxygen content in the terminal steel, which is 37×10-6. Most of the inclusions in the steel deoxidized by 1# AlMnCa alloy are spherical CaOcontaining compound inclusions, and 891% of them are smaller than 10 μm. The diameter of the inclusion bigger than 50 μm is not found in the final steels deoxidized by AlMnCa alloys. Whereas, for the steels deoxidized by AlMnFe alloys, most inclusions in the terminal steel are Al2O3 or Al2O3MnO inclusions, and a few of them are spherical, and only 768% of them are smaller than 10 μm. Some inclusions bigger than 50 μm are found in the steel D deoxidized by AlMnFe alloy.     

Effects of AlMnCa and AlMnFe Alloys on Deoxidization of Low Carbon and Low Silicon Aluminum Killed Steels

 To confirm the effects of AlMnCa and AlMnFe alloys on the deoxidization and modification of Al2O3 inclusions, experiments of 4 heat low carbon and low silicon aluminum killed steels deoxidized by AlMnCa and AlMnFe alloys were done in a MoSi2 furnace at 1 873 K. It is found that the 1# AlMnCa alloy has the best ability of deoxidization and modification of Al2O3 inclusions than 2# AlMnCa and AlMnFe alloys. Steel A deoxidized by 1# AlMnCa alloy has the lowest total oxygen content in the terminal steel, which is 37×10-6. Most of the inclusions in the steel deoxidized by 1# AlMnCa alloy are spherical CaO containing compound inclusions, and 891% of them are smaller than 10 μm. The diameter of the inclusion bigger than 50 μm is not found in the final steels deoxidized by AlMnCa alloys. Whereas, for the steels deoxidized by AlMnFe alloys, most inclusions in the terminal steel are Al2O3 or Al2O3 MnO inclusions, and a few of them are spherical, and only 768% of them are smaller than 10 μm. Some inclusions bigger than 50 μm are found in the steel D deoxidized by AlMnFe alloy.     

一种运用于高速ADC的采样保持电路设计

设计了一种用于Pipelined ADCs中的前置采样保持电路.从理论上推导了12bit、100MHz的模数转换器对采样保持电路各个子电路的性能指标要求,按此要求设计了增益增强型运放、自举开关等子电路.基于SMIC 0.13μm,3.3V工艺,Spectre仿真结果表明,在采样频率为100MS/s,输入信号频率为9.7656M时实现了81.9dB的信噪失真比(SINAD)和13.3位的有效位数(ENOB),无杂散动态范围(SFDR)可达94.9dB,功耗仅为24mW.输入直到奈奎斯特频率,仍能保持81.5dB的信噪失真比和13.2位的有效位数,SFDR可达到92.67dB.