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用宏程序进行椭圆的数控车削加工有两种方法,一种是用直角坐标系,一种是用极坐标系方法,都是用G73进行粗加工,用G70精加工.然而大部分工件毛坯是圆柱型材,G73加工效率低,如果用近似圆弧代替椭圆进行粗加工,用G71粗加工可以提高效率. 相似文献
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2007年中央1号文件强调"要用现代物质条件装备农业,用现代科学技术改造农业,用现代产业体系提升农业,用现代经营形式推进农业,用现代发展理念引领农业,用培养新型农民发展农业,提高农业水利化、机械化和信息化水平". 相似文献
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通过对泵用机械密封的整体工作环境分析,阐述了泵用机械密封故障及其失效的原因,以及运用泵用机械密封的原理与要求,提出了解决泵用机械密封故障的对策.通过进一步的强化泵用机械密封,以此逐步保障与完善泵用机械的安全性、密封性. 相似文献
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基于对燃烧系统(火用)转换元和输(火用)元组成及传递结构的分析,建立燃烧系统通用(火用)传递模型.依据系统(火用)传递特点、(火用)转换和传递元的性质和作用,定义、设计(火用)转换强度、燃烧产物实际热(火用)与理论热(火用)比、容积产热(火用)强度三个基本评价准则,有效预热权重、无效预热(火用)权重和散热(火用)权重三个辅助评价准则.由基本准则和辅助准则组成的评价体系,可对燃烧系统中能量与能质的利用作出全面评价.综合应用(火用)传递模型和评价准则,即可对燃烧系统进行完整的(火用)传递动态描述.为了获得(火用)传递的定量描述,在建立燃烧系统能量平衡和(火用)平衡方程的基础上,提出常见稳态燃烧系统(火用)传递计算的基本方法,并以计算实例概述了燃烧温度、(火用)传递速率和评价准则的计算要点及结果. 相似文献
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一种新型太阳能多功能热泵系统(火用)分析 总被引:1,自引:0,他引:1
对一种新型太阳能多功能热泵系统(SA-MDHP)进行了(火用)分析;并列出了SA-MDHP系统各部件的(火用)方程,将各部件输出的(火用)功率与输入(火用)功率的比值定义为部件的(火用)效率;研究结果表明,在给定条件下,SA-MDHP系统(火用)效率在0.15~0.4之间变化;为了有利于提高系统的(火用)效率,对各个部件(火用)损率变化趋势和各部件(火用)损率变化值进行了模拟研究,从研究结果可知,SA-MDHP系统(火用)损率最大的部件是压缩机,而(火用)损率最小的部件是毛细管. 相似文献
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通过对我国54家眼用制剂生产企业的问卷调研汇总,了解目前眼用制剂工艺、设备现状,了解眼用制剂生产企业执行GMP(2010)面临的主要问题及建议。以眼用制剂生产工艺及国内外眼用制剂生产质量控制文献资料为基础,客观分析目前眼用制剂生产企业执行GMP(2010)面临问题。 相似文献
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张家 《机械工业高教研究》2007,(5):109-112
对于“有没有用”,有必要追问:何谓有用、对谁有用、何时有用、何处有用、是大用还是小用、是有用还是无用等问题。以这些来思考教育,就会发现,教育之“用”,不仅是传授,更在于陶冶,其意义十分深远。讨论教育之用的出发点在于人,人的多种需要使教育有多方面之用,教育的地位由人的地位、而非政治经济的地位来支配。 相似文献
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Ines Pires Luisa Quintino Victor Amaral Tobias Rosado 《The International Journal of Advanced Manufacturing Technology》2010,50(5-8):557-567
New environmental, health and safety legislation, both in the EU and in the USA, is driving the need for the study of new welding processes, and the selection of the operational procedures that will reduce fume emissions and will promote a healthier, safer and more productive work environment. Actually, there are a significant number of publications related with gas metal arc welding hazards. However, for the new gas metal arc welding hazards variants, especially cold metal transfer, there is no data available concerning fumes and gases emissions. This paper attempts to point out ways of reducing the harmful effects of gas metal arc welding processes using different filler materials, different shielding gases, different operational welding procedures and three welding processes: gas metal arc welding process and two variants, pulsed gas metal arc welding and cold metal transfer. The effect of nitrogen oxide addition to the shielding gas composition on the amount of welding fumes and gaseous emissions produced during welding is also analysed. The amount of fume and gases generated during welding was measured over a range of current intensity and arc voltages, using the standard procedures contained in EN ISO 15011-2 [1]. The data presented give a summary of the different gas metal arc welding variants and their relations to fume generation rates and gases emitted. The results obtained give indications on measures to be taken in order to reduce fume and gas emissions. In general, the minimisation of fume formation rate can be achieved by using lower energy gas metal arc welding variants, gas shielding with low CO2 and O2 contents and “green” wires. 相似文献
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焦炉煤气样气处理系统是在线分析样气处理系统的技术制高点之一,焦炉煤气中的焦油、萘等有害污染物的处理非常困难,至今都未能完全解决。本研究提出的焦炉煤气原位整体式干法样气处理系统,能够很好适应焦炉煤气含尘量高,焦油和萘污染严重的特殊样气条件,具有体积小、免维护、零排放和响应快速的优点。采用该样气处理系统组合构建的焦炉煤气干法防爆氧分析系统已进入工程应用考核阶段。本设计的原位处理和原位分析,由于是干法样气处理技术,能够实现氧含量的高准确度在线分析,对安全生产有特殊的重要意义。 相似文献
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海洋平台一旦发生火灾、可燃或有毒气体泄漏等紧急情况,后果将极为严重。为了保证海洋平台人员和设备的安全,需要一个及时、准确、可靠的火气系统对现场的危险因素进行监控,将可能的事故及早消除或对已发生的事故使损失减到最低。本文主要介绍了火气系统的功能与定义,典型海洋平台火气系统的结构和组成,并且在大量工程实践的基础上,总结出海洋平台火气系统设计过程中需要遵循的设计原则。 相似文献
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介绍了气体分析仪在水泥窑尾烟室监测的使用过程,并介绍了分析仪取样探头、探头冷却水系统、探头吹扫气路系统、样气分析系统的结构;分析仪操作步骤、常见故障及处理措施。 相似文献
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Keeman Lee Jong-Min Kim Byeonghun Yu Chang-Eon Lee Seungro Lee 《Journal of Mechanical Science and Technology》2013,27(4):1191-1201
In this study, an investigation into the gas interchangeability and combustion characteristics of various gas compositions for domestic appliances was performed. In order to suggest the appropriateness of gas interchangeability using the specific gravity (SG) and the Wobbe index (WI) values, combustion characteristics included incomplete combustion and flame lifting were measured and observed for the upper and lower limits using the gas-oven as a domestic partial-premixed type appliance and the condensing boiler as a domestic premixed type appliance. The flame was stable, and the CO and NOx concentrations increased when the WI and SG values increased. Specifically, the behavior of the flame lifting changed between WI values of 52.0 MJ/Nm3 and 53.0 MJ/Nm3. The CO and NOx concentrations of the reference gas were approximately 173 ppm and 74 ppm for the gas-oven and 175 ppm and 35 ppm for the boiler, respectively. Consequently, a WI value of 53.0 MJ/Nm3 can be considered the flame lifting limit as the lower limit for gas interchangeability. For the upper limit of gas interchangeability, the CO and NOx concentrations varied significantly with the type of burner. 相似文献