Understanding the INTERNET: A guide for materials scientists and engineers

Newspapers and magazines are full of stories about the Internet and the coming “information superhighway.” Predictions for the future range from on-line video rentals and 500 channels of cable television to video telephones and global electronic libraries. Unfortunately, “infobahn” metaphors and hyperbole have obscured the fact that the the Internet is useful now and that it connects a significant fraction of the United States and the world. This article describes, without too many metaphors, the current and near-future capabilities of the Internet and provides basic information about access methods, popular services, and planned changes. In addition, the article also offers a brief introduction to “Net” culture and etiquette.     

连通孔泡沫铝材料的研究

采用渗流铸造法制作连通孔隙泡沫铝材料，即在压力作用下使熔融铝渗入食盐预制模的孔隙中，冷凝后再用水浸出食盐。研究了制作的工艺条件，测定材料的密度、透气度和除尘效率等性能。     

Modeling linear guide systems with CoFEM: equivalent models for rolling contact

Today’s machine tools are highly complex mechatronic systems capable to exert large translational and rotatory movements. In most cases rolling bearings are used to connect the moving parts to each other. As full FE models of rolling bearings can consume a large amount of degrees of freedom (DOF) efficient methods for reducing the DOF consuming rolling elements to more simple equivalent models are needed. As an example a linear guide system is used. A special feature of the considered linear guide is that the runner block consists of three separate parts, which are hold together only by pretension and friction. FE simulations of such linear guide system were not reported before in the literature. Beside the full FE model three equivalent contact models are presented. The first two equivalent contact models feature novel characteristics. Advantages and disadvantages of the equivalent models are discussed using as reference a slice of the full model and simulation results of static stiffness. The validation of the numerical models is also done using the general analytical solution of Hertz.     

Modeling linear guide systems with CoFEM: experimental validation

In this work a new efficient finite element (FE) model for rolling contact [RiBEM (rigid ball with equivalent material)] is shortly presented. The RiBEM model is used to efficiently compute the eigenmodes of a linear guide system. Experimental modal analysis of the real linear guide shows with 5?% error a very good correlation with the numerical results. Although the new contact model reduces computational time by more than ten times compared with the standard FE model, it is still too expensive for use within whole machine tool models. For this reason an equivalent, mesh independent and geometrically scalable model (rolling contact spring) based on the Hertz theory is introduced and also validated with the help of modal measurements. As a justification for the presented work, results with stiffness data from the manufacturer are also presented and less correlation with the experiment is found in this case.     

A guide to the crystallographic analysis of icosahedral viruses

Determining the structure of an icosahedral virus crystal by X-ray diffraction follows very much the same course as conventional protein crystallography. The major differences arise from the relatively large sizes of the particles, which significantly affect the data collection process, data processing and management, and later, the refinement of a model. Most of the other differences are due to the high 5 3 2 point group symmetry of icosahedral viruses. This alters dramatically the means by which initial phases are obtained by molecular substitution, extended to higher resolution by electron density averaging and density modification, and the refinement of the structure in the light of high non-crystallographic symmetry. In this review, we attempt to lead the investigator through the various steps involved in solving the structure of a virus crystal. These steps include the purification of viruses, their crystallization, the recording of X-ray diffraction data, and its reduction to structure amplitudes. It further addresses the problems attending phase determination and ultimately the refinement of a model. Finally, we describe the unique properties of virus crystals and the factors that influence their physical and diffraction properties.     

一种卧式单柱液压机导轨结构

介绍一种卧式单柱液压机导轨结构,其特征为:滑块下部与滑枕固定连接,滑枕支撑在导轨座上并可沿导轨座水平移动,导轨座固定在机身体上且沿滑块运动方向水平延伸.滑枕下部对称设有向滑块宽度方向的外侧伸出的翻边,翻边的上下两面及外侧面分别与导轨座的工作面相对,导轨座的各工作面上分别固定有钢导板,滑枕翻边的上下两面及外侧面分别固定有铜导板,各铜导板分别与相应的钢导板相贴合,钢导板及铜导板上分别设有润滑油孔.滑块作水平往复运动时,滑枕始终对滑块形成很好的支撑,抵消了滑块自重的影响,使主缸活塞杆的上下侧面受力均匀.     

出口伸缩导板位置控制计算

分析了带钢连续处理机组和精整机组卷取机前的出口伸缩导板在带钢穿带和甩尾时的位置控制方式,计算确定了出口伸缩导板摆动角度的绝对值编码器的脉冲数m与钢卷直径DC的关系,实现了根据钢卷直径的变化对出口伸缩导板摆动角度的自动控制,提高了卷取运行的稳定性和带钢的表面质量。     

万能轧机导卫系统浅析

介绍了马鞍山钢铁股份有限公司H型钢厂万能轧机导卫系统的装配形式、设计原则和使用特点，同时介绍了当前H型钢轧制新工艺中所采用的万能轧机导卫系统。     

Quick reference guide for β titanium alloys in the 00s

Beta titanium alloys provide useful combinations of physical and mechanical properties, as well as a wide range of processing options and generally good corrosion properties. Throughout the past several decades, many β alloys have been researched, yet only a handful of these currently enjoy commercial production. While the primary applications continue to be in the aerospace market, β alloys have demonstrated usefulness in other arenas. This article provides a quick reference guide for a large variety of common and not-so-common β titanium alloys. The information provided includes chemical composition, production status, mill product forms, applications, heat treatment, fabrication, corrosion resistance, physical properties, and mechanical properties. This paper was presented at the Beta Titanium Alloys of the 00’s Symposium sponsored by the Titanium Committee of TMS, held during the 2005 TMS Annual Meeting & Exhibition, February 13–16, 2005 in San Francisco, CA.     

Control of chip flow with guide grooves for continuous chip disposal and chip-pulling turning

This paper presents a new chip control method with guide grooves formed on the rake face to realize continuous chip disposal and chip-pulling turning. Chips are conventionally broken using chip breakers during turning operations for disposal. However, chips of highly ductile materials or thin chips generated in finishing can not be broken easily. In order to prevent the chips from jamming up, the authors propose to continuously guide the chips away from the cutting point. Special tool tips were developed and tested for guiding the chip. Chip controllability and mechanics of the chip-guided cutting are discussed in the present research.     

钢轨轧制过程典型导卫系统的有限元模拟

利用有限元模拟方法,对钢轨轧制生产过程中典型导卫系统进行模拟研究,借助大型有限元模拟软件MSC.Marc,分别讨论了入口导板和出口卫板对轧制过程以及轧件变形过程的影响。模拟结果表明,入口导板对轧件顺利咬入孔型以及轧件在该道次的变形过程产生显著影响,出口卫板对轧制过程的顺利进行产生显著影响。通过对模拟结果的分析认为,有限元模拟方法有助于实际生产过程中导卫系统的设计与优化;有限元模拟技术的应用,可提高导卫系统的可靠性,并对轧制过程提供有效而便捷的途径。     

A comparative evaluation of the effectiveness of water-base quenching media

Conclusion Out of the investigated water-base quenching media, solutions of bischofite ensured the most uniform hardness, the minimum amount of deformation, were the most serviceable in a wide range of temperatures (20–80°C), did not require intensive circulation, and had easily regulated cooling capabilities. This quenching medium is readily available, nontoxic, and inexpensive (37 rubles/ton) and is recommended for quenching material by immersion in vats of the open type.Institute of Metallurgy, Academy of Sciences of the USSR. NPO All-Union Scientific-Research Institute of Machine Building. ITTF, Academy of Sciences of the Ukrainian SSR. Translated from Metallovedenie i Termicheskaya Obrakotka Metallov, No. 10, pp. 21–25, October, 1986.     

冷轧带钢碎边导卫盒的改进

鄂城钢铁集团公司冷轧分厂为了解决宽带钢碎边剪刀具更换频繁问题，对碎迷导卫盒装置进行了改进，换刀具周期由10天一次改为2-3个月一次。     

Criteria for evaluating the cooling capacity of quenching media

Numerous criteria have been suggested for evaluating the cooling capacity of quenching media. Although the cooling capacity of a medium can hardly be evaluated by a single number, such data can be helpful in the initial stage of choosing the medium for quenching a specific part. Various criteria for evaluating the cooling capacity of polymer quenching media have been analyzed within the developed international standard based on ISO 9950 (for industrial quenchants). Those that can be calculated from results of tests of a medium by means of a Wolfson gauge, recommended by the ISO 9950 standard, have been chosen. The aim of the present work consists in determining the correlation between the criteria suggested by various researchers for various domestic and foreign quenching liquids on a polymer base. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 10, pp. 18–21, October, 1998.     

Interactions of silicone rubbers designed for electrical engineering applications with aqueous media

Interactions of a number of electrical engineering silicone rubbers with water and aqueous salt, weakly acidic, and weakly basic solutions were studied by measuring contact angles. A mechanism for leakage currents along the surfaces of silicone insulators was proposed.     

Aminic nitrogen-bearing polydentate Schiff base compounds as corrosion inhibitors for iron in acidic media: A quantum chemical calculation

Quantum chemical calculations based on DFT method were performed on three polydentate Schiff base compounds (PSCs) used as corrosion inhibitors for iron in acid media to determine the relationship between the molecular structure of PSC and inhibition efficiency. The structural parameters, such as the frontier molecular orbital energy HOMO (highest occupied molecular orbital) and LUMO (lowest unoccupied molecular orbital), the charge distribution of the studied inhibitors, the absolute electronegativity (χ) values, and the fraction of electrons (ΔN) transfer from inhibitors to iron, were also calculated and correlated with inhibition efficiencies. The results showed that the inhibition efficiency of PSCs increased with the increase in E_HOMO and decrease in E_LUMO − E_HOMO; and the areas containing N atoms are most possible sites for bonding the metal iron surface by donating electrons to the metal.