Investigation of the effects of tool micro-geometry and coating on tool temperature during orthogonal turning of quenched and tempered steel

Reliable information about tool temperature distribution is of central importance in metal cutting. Application of dedicated charge-coupled device (CCD) sensor based near infrared (0.85–1.1 μm) imaging technique to the orthogonal turning of quenched and tempered steel is presented. Special attention was paid to the role of calibration on the interpretation of isotherms. Experimental results from systematic studies devoted to the role of heat source width, cutting parameters, edge micro-geometry and coating indicate the flexibility and reliability of this approach. Results compare favourably with those from other techniques capable of indicating tool isotherms as well as with numerical models based on FEM.     

在高温下浇筑碾压混凝土的研究

三峡大坝混凝土总量约2700万m3，其中碾压混凝土900多万m3。混凝土浇筑历时16年，根据施工进度安排，夏季必须浇常规混凝土及碾压混凝土。因此，必须研究高温条件下浇筑碾压混凝土的有效工艺措施和施工方法。经过充分调研和分析，采用复盖保温材料的办法可控制混凝土温升过程。保温材料选用高压聚乙烯泡沫塑料，因其导热系数小，且能防水、不腐烂、柔软、质轻、便于施工，能适应全面浇筑时高低不平及台阶等不平整仓面的隔温复盖。本文对选用之高压聚乙烯泡沫塑料作为隔热保温材料，用于三峡工地高温季节混凝土浇筑，根据现场试验，概述了高压聚乙烯泡沫塑料材料选择、大坝保温用乙烯泡沫的厚度选择、高压聚乙烯泡沫板作隔温材料的敷工艺、以及现场实测高压聚乙烯泡沫板材的保温效果和分析。     

Probabilistic Material Degradation under High Temperature, Fatigue, and Creep

This paper describes the development of methodology that provides for quantification of uncertainty in the lifetime material strength degradation of structural components of aerospace propulsion systems subjected to a number of diverse random effects. The methodology is embodied in the two computer programs PROMISS and PROMISC. These programs form a material‐resistance model used in an aerospace structural‐reliability program NESSUS. A probabilistic material‐degradation model, in the form of a postulated randomized multifactor interaction equation, is used to quantify lifetime material strength. Each multiplicative term in the model has the property that if the current value of an effect equals the ultimate value, then the lifetime strength will be zero. Also, if the current value of an effect equals the reference value, the term equals one and lifetime strength is not affected by that particular effect. Presently, the model includes three effects that typically reduce lifetime strength: high temperature, mechanical fatigue, and creep. The paper also includes the statistical analysis of experimental data for INCONEL 718 obtained from the open literature. This statistical analysis of data provided regression parameters for use as the empirical material constants of the model, thus calibrating the model specifically for INCONEL 718. Model calibration was carried out for three variables, namely, high temperature, mechanical fatigue, and creep. Finally, using the PROMISS computer program, a sensitivity study was performed with the calibrated random model illustrating the effect of each variable upon random lifetime strength.     

薄膜式LNG运输船温度场研究

液化天然气运输船液货舱热维护系统是一个结构复杂的、具有第三类边界条件的、多层平壁的稳态导热与自然对流及辐射换热相互耦合的三维复杂传热系统。针对这一复杂系统，考虑了船体主要构件、骨材、空腔空气对流、表面间的辐射对换热的影响，建立了数学模型，并给出了基于通用软件ANSYS的数值计算方法；还以某艘LNG运输船为例，进行了温度场的有限元分析。结果表明，所给出的对LNG运输船液货舱热维护系统的热分析方法是有效的。     

设备基础大体积混凝土施工及裂纹控制

在大庆200MW火电厂锅炉等设备基础的大体积混凝土施工过程中，通过严格执行模板设置、混凝土的搅拌、输送、振捣、养护等工艺规范，采取定时定位监测凝结水化热的温度等工艺措施，有效地控制了大体积混凝土浇筑后可能产生的裂纹。     

The EFG process applied to the growth of silicon ribbons*

The development of edge-defined, film-fed growth (EFG) techniques for silicon ribbons has prompted analyses of appropriate die materials, die shapes, meniscus shapes and thermal gradients. The requirement for high electronic quality of the ribbons, in conjunction with the high effective solute distribution coefficients expected for EFG, narrows the choice of die materials primarily to graphite and fused silica. The shape of the meniscus between crystal and die has been calculated. This shape, together with contact angle information, is used to determine design criteria for both graphite and silica dies. The effect of crystal growth on the temperature gradient ahead of the growth interface has been calculated in terms of the ribbon thickness and an empirical parameter characterizing the radiating environment of the growth apparatus. Numerous 25 mm wide × 0.3 mm thick ribbons from carbon dies and a few small ribbons from silica dies have so far been grown. The ribbon quality is discussed. Work supported by the National Science Foundation.     

X射线衍射法测定高炉风口平面径向温度分布

利用Ｘ射线衍射法，测定经过不同高温热处理的入炉焦炭中碳（００２）晶面Ｘ射线衍射峰半高宽，作出Ｂ－Ｔ温度温度标定曲，并根据此曲线，推断出宝钢大型高炉风口平面径向焦炭温度的分布情况。     

香豆硼冻胶压裂液

本文论述了香豆硼冻胶的组成、性能及现场试验情况。室内试验及现场实践表明，香豆硼冻胶是一种流变性好、摩阻低、易破胶、低残渣、低伤害、适用于８０℃以下低温及中温的优良压裂液。     

On the ‘reaction in chain’ in the thermoelectric conversion of energy through thermocouples: Theoretical implications of the phenomenon

It is shown, experimentally, that in certain initial conditions of temperature, and for certain parameters, a ‘reaction in chain’ may start in a thermocouple, and produce a ‘permanent regime’, through which heat from a single course is converted into electrical energy. It is shown, theoretically, that the phenomenon occurs when compensation of heat losses due to thermal conduction, through Peltier and Thomson heat is realized, so that the efficiency is affected only by the Joule effect, and may attain much higher values than through conventional operation of these thermoelectric devices, conventional peration requiring two heat sources, a hot and a cold one.     

Condensation of R407C in a horizontal microfin tube

This paper describes experimental results that show the effects of mass velocity and condensation temperature difference on the local heat transfer characteristics during condensation of R407C in a horizontal microfin tube. The experiments were performed at the saturation temperature of 40 °C, the refrigerant mass velocity of 50, 100, 200 and 300 kg m⁻² s⁻¹, and the condensation temperature difference of 1.5, 2.5 and 4.5 K. A superficial heat transfer coefficient for the vapor phase was obtained by subtracting the heat transfer resistance of condensate film estimated by using a previously developed theoretical model of film condensation of pure vapor from the overall heat transfer resistance. On the basis of the analogy between heat and mass transfer, an empirical equation for the superficial vapor phase heat transfer coefficient was developed. The heat transfer coefficient predicted by the combination of the previously developed theoretical model of film condensation of pure vapor and the empirical equation of the superficial vapor phase heat transfer coefficient agreed with the measured values with the r.m.s. error of 9.2%.