共查询到20条相似文献，搜索用时 218 毫秒
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文章利用相关分类号和关键词对以渗碳工艺为主题的中国专利进行检索,并以检索结果为基础对国内渗碳工艺的专利申请量、授权量、主要申请人进行统计,以及对气体渗碳、固体渗碳和液体渗碳的技术现状和发展趋势进行分析。 相似文献
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丝锥是用于加工螺纹孔的一种常用钳工工具,在使用中稍不注意就会出现折断的现象。根据多年的工作实践经验,总结出丝锥折断的常见原因及折断后的处理技巧。 相似文献
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目前,在汽车行业,渗碳是使用最为广泛的表面硬化工艺方法,而乙炔作为渗碳介质的工艺已被广泛的开发和应用,2013年我公司购买进口设备--双室真空渗碳油淬炉,主要用于变速箱油泵齿轮低压真空渗碳,该设备采用低压乙炔渗碳为脉冲式,即强渗→扩散→强渗→扩散,多个循环后达到所要求的渗层深度,由于没有类似可控气氛中的氧探头传感器,无法对低压渗碳过程进行直接监控,采用乙炔真空渗碳数据库,对渗碳和扩散过程进行精确监控。使渗碳层更加均匀,变形量小等优点。 相似文献
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在详细分析圆弧齿轮渗碳工艺存在的两个主要问题的基础上,针对渗碳工艺中存在的问题提出了对应的渗碳工艺改进策略,对提高渗碳工艺质量起到一定的参考作用。 相似文献
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本文简要论述了材料力学中画拉压杆轴力图的一种方法，这种方法只需根据杆上的外力，不需要使用截面法就可以直接画出拉压杆的轴力图，我们称为“快捷方式”。我们以杆上只有集中力，杆上有均布载荷作用和杆的轴线沿垂直方向的三种情况说明这种方法的基本原理，实践表明使用“快捷方式”讲课简洁明快，学生很容易理解，其教学效果非常好。 相似文献
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F.M. Clark 《Journal of The Franklin Institute》1933,216(4):429-458
Throughout this paper data have been presented showing that the apparent inconsistency of the reported dielectric strength behavior of insulating liquids can be satisfactorily correlated if proper consideration be given to the state of the “purity” of the liquid itself. As a result it is suggested that insulating liquids should be classified as (a) “pure,” indicating those liquids free from dissolved gases as primary “impurities”; and (b) “impure,” including those liquids which contain dissolved gas. The breakdown mechanism depends on the distinctive behavior of these two general classes. “Pure” liquid breakdown is a function of charged particle formation. In part, this may be caused by the assumption of a charge by molecular aggregates, colloidal-like in nature. In part, the charge may arise from molecular ionization by collision. The latter occurs chiefly in the voltage range immediately preceding electrical rupture and is the chief cause of “pure” liquid insulation failure. The presence of the first type of charge—that is, the existence of a difference of potential between molecular aggregates and the liquid—is chiefly responsible for the variation in the time factor to breakdown.The breakdown of “impure” liquids is a function of dissolved gas elimination. This dissolved gas is eliminated as a result of changing solubility produced (a) by electro-striction effects, or (b) by changing pressure or temperature. The presence of secondary impurities such as dust particles and fibers, acts chiefly through the effect on increasing gassing tendencies.It is suggested further that the localization of dielectric breakdown in liquids, irrespective of the type or degree of “purity,” is chiefly in the “neutral membrane” located near the electrodes and formed by the discharge of particles. Such a “neutral membrane” results in a space charge effect giving marked drop in potential and as a result promoting ionization by collision effects in “pure” liquids and electro-striction effects in “impure” liquids. 相似文献
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党的十八届五中全会指出,全面深化改革的一项重要任务,即完善社会主义市场经济体制建立市场决定价格机制。就社会主义市场经济而言,“全面放开竞争性领域商品服务和价格”是价格改革中的“关键性战役”,面对“全面放开”之后的担忧和期待,本文从“政府说了算”还是“市场说了算”,“收”“放”之“困”从何而来,“经济新常态”下的必然选择,未来政策走向及经济影响四个方面论述了市场经济条件下全面实现市场决定价格机制的作用和意义。 相似文献
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首先,构建多个地方政府之间的跨界水污染治理博弈理论模型,对地方政府的行为选择进行分析,结果表明地方政府跨界环境污染治理投入的纳什均衡最优小于整体的帕累托最优,二者呈现背离状态,并且背离程度随着参与跨界环境污染治理地区的增加而增加,导致"囚徒困境"和"公地悲剧"局面;其次,利用我国2012年62个主要水库和湖泊相关数据为研究样本,实证分析行政单位数量对水资源质量的影响,对理论假设进行验证;最后提出解决跨界水污染治理的政策建议。 相似文献
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J.L. Finck 《Journal of The Franklin Institute》1948,245(4):301-317
In this paper the concepts “equilibrium” and “reversibility” are examined from the standpoint of the number of independent variables which define a thermodynamic system. The endeavor is made to show that the number of independent variables which are selected is crucial to the basic concepts as well as to the second law of thermodynamics. If this number is less than the minimum required to define the system completely, the equation of state for the internal energy will be incomplete. It is our practice to employ incomplete equations of state, and this results in processes which we consider to be irreversible. The Kelvin-Planck and Clausius principles are shown to be somewhat related to the first law of thermodynamics, and their validity arises from the fact that the equations of state which are used are incomplete. If these equations were complete, that is, if the number of independent variables were not less than the minimum required to describe the systems completely, we should have complete conversion of heat into work, as well as work into heat. The difficulties in realizing complete equations are considered.The entropy concept is considered in detail, and it is shown that there are serious limitations in its application. 相似文献
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拍弦是网球传接球过程中直接的载体．它的好坏直接影响到传接球的质量和球员技术的发挥。通过对网球击球的力学分析以及拍弦种类、强度的了解,旨在提高网球爱好者对网球拍弦的认识,为网球爱好者在选择拍弦时提供参考。 相似文献
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[目的/意义]对比分析我国“双一流”大学与美国知名大学科研合作网络特征,旨在为我国“双一流”大学建设提供参考。[方法/过程]收集我国“双一流”大学与美国部分知名大学2014—2018年在Web of Science数据库中校际合著论文,构建频次矩阵、Salton指数矩阵,采用社会网络分析方法,运用Ucinet、Netdrew、Pajek、VOSviewer等工具,从科研合作网络的整体网络密度、点度中心性、核心边缘分析、聚类分析四个角度对两者的科研合作网络特征进行对比分析。[结果/结论]我国“双一流”大学之间已建立起广泛的科研合作,但与美国知名大学相比,我国“双一流”大学存在科研合作强度弱、科研合作参与度较低、科研合作分布不均衡等特征。 相似文献
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The Graph-Theoretical Field Model provides a unifying approach for developing numerical models of field and continuum problems. The methodology examines the field problem from the first stages of conceptualization without recourse to the governing differential equations of the field problem; this is accomplished by deriving discrete statements of the physical laws which govern the field behaviour. There are generally three laws, and these are modelled by the “cutset equations”, the “circuit equations”, and the “terminal equations”. In order to establish these three sets of equations it is expedient first to spatially discretize the field in a manner similar to the finite difference method and then to associate a linear graph (denoted as the field graph) with the spatial discretization. The concept of “through” and “across” variables, which underlies the cutset and circuit equations respectively, enables one to define the graph in an unambiguous manner such that each “edge” of the graph identifies a pair of complementary variables. From a knowledge of the constitutive properties and the boundary conditions of the field it is possible to associate terminal equations with sets of edges. Since the resulting sets of equations represent the field equations, these equations provide the basis for a complete (but approximate) solution to the field or continuum problem. In fact, this system approach uses a two part model: one for the components and another for the interconnection pattern of the components which renders the formulation procedures totally independent of the solution procedure.This paper presents the theoretical basis of the model and several graph-theoretic formulations for steady-state problems. Examples from heat conduction and small- deformation elasticity are included. 相似文献
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“同一健康”失序与全球疫情问题 《科学学研究》2021,39(12):2121-2128
历史上反复出现的重大公共卫生突发事件,大都是“同一健康”失序的体现,其背后则潜藏着人与动物二元对立的认识论误区。理性的人与作为机器的动物之间的森严等级关系,造成了“自我”对“他者”的支配与控制,鼓励了人类对动物和环境的践踏。然而在人类对动物和环境肆意妄为的同时,其自身也以全球疫情、气候变暖等形式受到了反噬。历次针对疫情的“战争总动员”就源于普遍联系的健康网络中人与动物关系的破坏。如果我们不认真反思这种认识论上的误区,那么历次疫情爆发不过是未来更多危机的彩排。只有瓦解泾渭分明的二元对立,在全球范围内展开普遍合作、践行“同一健康”议题,人类才能与动物、环境共同生活与共同发展,在拥有“同一世界”的同时,享有“同一健康”。 相似文献
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Heat effects in fixed-bed sorption columns are often quite large and have a pronounced effect on the sorption kinetics. Proper design of such systems must include consideration of these effects.A method is developed for computing the maximum possible bed temperature. The model is tested on two systems: (1) the Linde molecular sieve 4 A/water system and (2) the Alcoa activated alumina F-1/water system. Since the predicted temperatures appeared to be low for the latter system, the model was refined by the inclusion of the isosteric integral heat of adsorption. Tests on the activated alumina show considerable improvement.The isosteres of two sorption therm correlations are investigated. The results show that the heat of adsorption of water on the alumina varies logarithmically with sorbate concentration—approaching high values at low concentrations and approaching the heat of vaporization of water at high concentrations. The results also suggest that the isosteric heat of adsorption behavior may be of use in assessing the “goodness of fit” of sorption therm correlations. 相似文献
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采用科学的方法调整竞技状态、合理安排运动训练负荷、预防过度训练和运动损伤。采用文献资料法、实验法,针对羽毛球运动员的运动及供能特点,通过对多项相关生理生化指标的测试和分析,客观地诊断羽毛球运动员竞技状态、运动疲劳的程度和身体恢复的情况。反应时、肌力、心率、最大做功能力、血尿素、血睾酮、血乳酸等几项指标能够较好反应羽毛球运动员训练效果,指导科学训练。 相似文献