Thermodynamics of Ti in liquid steels and slags

Thermodynamics of Ti in liquid steels and slags was studied in order to establish a data base for the prediction of TiO_x and TiN formation in liquid steels.The interaction parameters between Ti and i（i = Cr,Ti,Al, Si,Ni,Mo,Nb,N,O） in liquid iron and the equilibrium constants for the formation of TiN and TiO_x in liquid iron were determined as a function of temperature.In view of high Ti yield during ladle treatment,thermodynamics of titanium oxides in ladle slags was studied as well.Activity coefficient and redox equilibrium of TiO_x in MgO saturated CaO-Al₂O₃ slag are also discussed by measuring the distribution ratio of Ti between slag and iron melts and the Ti³⁺/Ti⁴⁺ ratio in slag at 1 873 K.     

Modeling the flow curve of hot deformed austenite under industrial rolling conditions

A 0.02%C plain carbon steel and a 0.11%C Nb-modified steel were tested in compression in the austenite temperature range.The critical strains for the initiation of dynamic recrystallization were determined from the 41 stress-strain curves obtained,using the double differentiation method.The work hardening behavior up to the critical strain was analyzed with the aid of a dislocation density model and the work hardening parameters r and h were derived in this way.These parameters were used to model the aus...     

Parenteral calcium gluconate supplementation: efficacious or potentially disastrous?

A new instrument is described for use in the sagittal ramus split osteotomy by Obwegeser. This modified channel retractor simplifies the sagittal ramus osteotomy procedure, allows clear vision and easy access, and protects adjacent tissues.     

VELOCITY ANALYSIS OF A PLANAR MECHANISM USING A METHOD FROM STATICS

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Operation and maintenance field experience for off‐grid residential photovoltaic systems

The field performance of photovoltaic systems has been studied extensively for many applications and a number of databases exist in the United States and internationally. However, these databases focus almost exclusively on the system elecrical performance. Published information on the operation and maintenance (O&M) experience and costs for photovoltaic systems is almost nonexistent. At a time when photovoltaics is being considered as a viable option for distributed energy generation, it is critical that maintenance experience be captured to identify lifecycle costs and/or levelized energy costs for these systems, as well as to identify areas for system and component improvements. This paper addresses the data collection, analysis and results of an off‐grid residential customer service program offered by the Arizona Public Service (APS) Company over a six‐year period from 1997 through 2002. Standardized, packaged photovoltaic systems were offered and operated by APS through a lease arrangement with customers throughout the state of Arizona. The operation and maintenance records for these systems were carefully tracked and analyzed. The O&M costs, database development, cost drivers, lifecycle cost implications, and lessons learned are presented and discussed. Copyright © 2004 John Wiley & Sons, Ltd.     

无线接入——广泛提供基本电话业务的有效方法

本文综述了无线接入的技术要求，无线／蜂窝移动通信的演变，以及针对大范围电话业务采取的无线接入的技术可行性和所遇到的设计挑战。     

标准三脚复位监控器的手动复位

为设计增加手动复位时一般采用一只带手动复位输入的新器件.但是,只要增加几只小电阻,一个标准的三脚复位监控器就足以应付多数应用.     

FLOATING RATE OF FRAZIL ICE PARTICLES IN FLOWING WATER IN BEND CHANNELS——A THREE-DIMENSIONAL NUMERICAL ANALYSIS

In this article,based on the theory of two-phase flow and laboratory data,a three-dimensionally model is developed to simulate the floating rates of frazil ice particles in water under covered condition.The Lagrangian trajectory method is used in the three dimensional simulation for floating rates of frazil ice particles along a 180o bend channel.The velocity profiles in longitudinal and transverse directions,the turbulence intensity,and the residual pressure are simulated.Under the condition of gravitation...     

Molecular Weights of Lignosulphonate and Carbohydrate Leached from Sulphite Chemimechanical Pulp

Abstract

The molecular weights of both the lignosulphonate and carbohydrate fractions leached from sulphite chemimechanical pulps Increased as the leaching proceeded. Lignosulphonate molecular weights rose from 11000 to 61000. Values for the carbohydrate fractions were lower, ranging from 6000 to 17000. For the lignin, the diameter of the equivalent sphere corresponding to the whole sample leached was considerably Higher then the medium-pore diameter of the fiber. This discrepancy Indicated that the lignosulphonate macromolecule in the fiber wall adopted a flat conformation.