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Abstract Flash welding, through conferring a number of important advantages, such as high productivity, good-quality welds, and suitability for welding of components with large cross-sections, is extensively used for shop welding of rails, plating of hot coils, welding of wheel rims, etc.1–3 More compact welding facilities are also being sought through further exploitation of mechanical control technology for practical applications in job-site welding of rails, H-steel sections, etc.4 相似文献
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目的: 评价湖南省人民医院院区2016年利奈唑胺临床应用的合理性及有效安全性,为其临床应用提供参考。方法: 采用回顾性研究,利用医院信息管理系统调取2016年使用利奈唑胺患者病例资料,设计调查表,统计用药合理率,分析不合理原因;计算临床治愈率,病原菌清除率及综合治愈率;监测用药前后红细胞、血红蛋白、血小板下降程度。结果: 利奈唑胺临床应用合理率为48.1%,不合理原因主要是适应症把握不准确及疗程不合理;临床有效率为40.4%,病原菌清除率为42.3%,综合治愈率为56.4%;骨髓抑制发生率为21.2%,发生的平均年龄为(81.4±8.7)岁,平均用药时间为(13.6±5.6) d。结论: 我院区利奈唑胺临床应用合理性有待提高,正确把握适应症和疗程将很大程度提高合理率;综合疗效尚可,老年患者需特别注意骨髓抑制的发生。 相似文献
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Ag—Cu—Ti钎料中Ti元素在金刚石界面的特征 总被引:18,自引:2,他引:16
研究了金刚石钎焊接头中碳化物形成元素Ti与金刚石(或石墨)之间的相互作用行为。通过对接头界面处的成分分布和断口形貌观察,分析了Ti的作用机理、新生儿合物TiC的断口形及生长规律,结果表明:在一定的条件下,Ti元素与组成金刚石(或石墨)的碳元素发生反应形成TiC层;碳化物层使钎料与金刚石之间产生冶金结合;TiC与金刚石之间存在有明显的界面,TiC断口的微观表面形态呈韧窝状;在金刚石表面初始形成的TiC的生长方向与金刚石的晶向指数有关。 相似文献
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S. J. Drew M. A. Mannan K. L. Ong B. J. Stone 《International Journal of Machine Tools and Manufacture》2001,41(4)
Most investigations of chatter have made the assumption that torsional vibration is not a significant factor. Some recent work has shown that chatter in grinding is affected by a change in the torsional stiffness of the workpiece drive. Also, a theoretical model of grinding chatter has been developed that confirmed the significance of torsional effects. However, the model for the grinding force was assumed to be a dynamic equivalent of a published steady-state model. This paper describes tests conducted to measure the variation in force caused by an oscillation in workpiece speed. The oscillating test results indicate that the torsional vibration of the workpiece may well be a significant effect on chatter in grinding. Moreover, as the grinding force changes with workpiece speed, it may be possible to use variation of workpiece speed at high frequency to reduce chatter. 相似文献
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The effect of anomalies detected in x-ray diffraction and metallographic examination of welded joints on the properties of resistance butt welded joints in 1201 aluminium alloy is determined and recommendations are given for the standards for permissible defects. 相似文献
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none 《腐蚀工程科学与技术》2013,48(1):53-56
AbstractThe effect of sulphides on the corrosion of zinc in artificial sea water has been studied over the pH range 6·5 to 8·6. A comparison of the weight loss and potential values of specimens in aerated and deaerated sea water, with or without the addition of sulphide, has shown that at pH values > 7·2 the presence of sulphides increases the corrosion, while at lower pH values it is partially inhibited. This is related to changes in the concentration of S2- ions in the solution. The corrosion products formed in the more corrosive solutions were shown to consist mainly of ZnS, which is believed to cause loss of adhesion of the corrosion products on the zinc surface, and thus to accelerate the corrosion. 相似文献
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引线装填机是一种可自动将有引线的电子元件(如二极管或电阻等)的引线装填在接料盒中的设备,其采用的PLC控制技术不但提高了作业效率和可靠性,而且使整个控制线路更简洁、控制过程更精准. 相似文献
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Progress in application of rare metals in superalloys 总被引:1,自引:0,他引:1
Rare metals play an important role in development of superalloys. Over the last two decades, the application of the rare metals in superalloys has achieved progress significantly. They present multi-beneficial effects for strengthening the matrix and the c0phase, increasing the lattice misfit, cleaning the grain boundary, improving the carbides and eutectics, refining the grain, stabilizing the oxidation film, etc., so that the elevated temperature rupture life and elevated temperature oxidation resistance are improved significantly, leading to a broad application in the superalloys. In order to meet the higher demand for better superalloys in the future, more intensive research is necessary on the effects of the rare metals on the superalloy, and especially on the combination effect of various rare metals and mutual influence among them. Utilization of the computational materials science and combinatorial high throughput experiment will be of importance in application of rare metals in superalloys. 相似文献
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Conclusions The world energy crisis must not cause limitations to the development of industrial production and in particular it must not decrease the rate of development of heat treatment but must stimulate rationalization of the energy consumption of heating operations.Heat treatment, which is by nature an energy consuming operation, is simultaneously an energy saving one. This energy paradox is the result of the dissimilar requirement of energy in the production of steel and in its heat treatment, the reason for which is the fact that from the energy point of view heat treatment is several times more economical than the production and use of steel without heat treatment. As the result of this, to decrease the energy consumption of the economy of each country as a whole it is necessary to use heat treatment of metallic materials in industry on the widest possible scale.There exist large possibilities for decreasing energy consumption in the heat-treatment industry. The simplest form of economy in energy in heat treatment of metals is a decrease in its consumption without additional capital expenditures by improvement in the organization of production. More complex and requiring a longer time is the use of new production operations and equipment. The combined use of these reserves must provide a decrease in energy consumption in heat treatment of at least more than 10%.Presented at the All-Union Conference on "Economy in Metal and Energy on the Basis of the Introduction of Progressive Methods of Heat and Chemicothermal Treatment" held in Penza on May 16–18, 1984.Institute of Precision Mechanics, Polish Peoples Republic. Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 3, pp. 17–24, March, 1985. 相似文献
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铝土矿酸介质中铁的行为 总被引:4,自引:1,他引:4
研究了高温高压条件下铝土矿中铁在硫酸介质中的溶解行为,结果表明:在一定的温度条件下,铝土矿的赤褐铁矿能较好地溶于硫酸溶液中,而铝土矿中含铝矿物的性质不发生变化,从而为铝土矿的进一步加工利用提供了条件。详细讨论了反应温度、反应时间、硫酸浓度、液固比等因素对铁的溶解行为的影响,得出了在最佳工艺条件,即在反应温度160℃、反应时间3h、硫酸浓度0.7mo1/L和液固比6:1时除铁效率最高。 相似文献
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B. Valdez Salas M. Schorr Wiener L. Rioseco de la Pea M. Navarrete Bedolla 《工业材料与腐蚀》2000,51(10):698-704
Mexico is the third world producer of geothermal electricity. The power generation infrastructure installed for the exploitation of geothermal steam, includes a wide variety of materials for fabrication of equipment and structures exposed to a very aggressive, geothermal environment. In the geothermal fields of Mexico there are several microorganisms causing corrosion of carbon steel (CS) and stainless steel (SS) and biodeterioration of composite materials: fibre‐glass reinforced polyester (FGRP) and steel reinforced concrete (RC). These microorganisms were isolated from natural geothermal environments, identified and utilised in simulated corrosion and deterioration laboratory investigations. Metallographic analysis and SEM were performed to determine the morphology of microbiological attack on SS. Electrochemical corrosion tests showed that the bacteria induced corrosion on UNS S31600, preferentially at grain boundaries. The composite materials underwent physico‐chemical deterioration processes promoted by the harsh environmental field conditions, involving microorganisms. 相似文献