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从人体健康性的角度引入"热健康"、"热的亚健康"和"热不健康"三个概念,并以人体热舒适和热健康为出发点,参考ASHRAE标准的七级热感觉标度,将热环境分为4类(共7级),给出了热环境、热感觉、热调节区域、热调节方式以及人体状态和热健康状况的对应关系,分析了不同的热环境状况对人体热舒适和热健康的影响,并讨论了人体处于热舒适和热健康状态的最佳热环境. 相似文献
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简要介绍一种分流式冷凝热部分热回收水冷冷水机组的系统原理,将其与一般的冷凝热部分热回收水冷冷水机组的性能进行分析对比。测试结果表明,该方案下的冷凝热部分热回收水冷冷水机组,在应用上可行,同时可达至紧凑型产品设计。进而探讨该方案在冷凝热部分热回收风冷冷水机组和冷凝热部分热回收空气源热泵冷(热)水机组的产品设计中的应用。 相似文献
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太阳能热发电是将太阳能转化为热能,通过热功转化过程发电的技术[1]。利用这种技术的电站被称为太阳能热发电站。根据聚光方式的不同,主流的太阳能热发电技术分为塔式太阳能热发电、槽式太阳能热发电、碟式太阳能热发电和线性菲涅耳式太阳能热发电4种形式。 相似文献
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热驱动热声制冷技术利用热声发动机输出的高强度声波驱动热声制冷机实现制冷,即实现热—声—冷能源转换,是一种环境友好、近零电耗且热源适应性好的新型绿色制冷技术。热驱动热声制冷系统工作温跨大,可实现室温至液氦温区不同制冷需求,在多个领域具有广阔的应用前景。本文以热驱动热声制冷技术近三十年来的发展为基础,介绍了热驱动热声制冷原理和分类,从热驱动室温热声制冷机和热驱动低温热声制冷机两个方面综述了研究现状和发展方向,对该技术在室温制冷、余热/冷回收、天然气液化和低温制冷等方面的应用及相关研究进行了归纳分析,并指出未来的研究需要在热声新流程、谐振机构、高效热声转换、低品位能源利用、工程样机实用化等方面实现协同突破,形成效率高、功率大、起振温度低、可实现极低温、稳定可靠的热驱动热声制冷技术,从而推动新型绿色制冷技术的科学发展与应用。 相似文献
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本文对热环境与人体健康的关系、热环境的评价指标以及热舒适标准做了一个综合性的描述.认为可以通过合理的组合室内热环境参数,不仅可以达到热舒适和热健康,还可以节能,并且阐述了基于节能的室内热环境设计参数的选择方法. 相似文献
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J. Cyril Asokan Paravasu J. Jerald Kumar Sumit G. Kanagaraj 《Materials and Manufacturing Processes》2017,32(6):638-644
This study investigates the impact of machining factors on the performance of additive mixed micro-electric discharge drilling of 316L stainless steel. The effects of three kinds of powder, powder concentration, voltage, capacitance, feed rate, and speed on tool wear rate, material removal rate, taper angle, and overcut (OC) were also investigated. The experimental results show that adding additives to the dielectric enhanced rate of material removal and reduced rate of tool wear significantly. Mixing powder with dielectric increased the length of the sparking, resulting in significant OC, and process performance also improved with the increase in amount of powder added. Further, scanning electron microscopy analysis was carried out to examine the surface characteristics and material migration properties, which confirmed that the properties of the machined surface are indeed significantly improved. 相似文献
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This paper discusses a mathematical model for computing the thermodynamic properties of propane, n-butane, isobutane, and their mixtures, in the fluid phase using a method based upon statistical chain theory. The constants
necessary for computations such as the characteristic temperatures of rotation, electronic state, etc. and the moments of
inertia are obtained analytically applying a knowledge of the atomic structure of the molecule. The paper presents a procedure
for calculating thermodynamic properties such as pressure, speed of sound, the Joule-Thomson coefficient, compressibility,
enthalpy, and thermal expansion coefficient. This paper will discuss, for the first time, the application of statistical chain
theory for accurate properties of binary and ternary mixtures including propane, n-butane, and isobutane, in their entire fluid phases. To calculate the thermodynamic properties of Lennard-Jones chains, the
Liu-Li-Lu model has been used. The thermodynamic properties of the hydrocarbon mixtures are obtained using the one-fluid theory.
Paper presented at the Fifteenth Symposium on Theremophysical Properties, June 22–27, 2003, Boulder, Colorado, U.S.A. 相似文献
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本文是作者再次对标准和标准化的概念进行讨论。首先讨论的是标准化的目的、主体和对象。作者认为标准化的目的是控制、有序化和统一化;标准化的主体是人/机构;标准化对象可以是具体的或抽象的事物,也可以是它们的组合;任何事物都可以抽象地表达为实体(entity)。第二,作者讨论了标准和标准化的本质以及它们的作用;认为从内容角度看,标准是匹配问题解决方案,也是为标准化对象规定需要满足的要求;从实施角度看,标准是规则;标准化则是制定、实施、传播标准的过程;标准的作用是能够创建并组织现实世界,并能够为相关方建立互相交流和共同理解的基础;标准化的作用是对创新方案进行选择和简化,阻止现实世界过度无序化发展,形成复杂化和简化之间的平衡。第三,作者讨论了标准的记录形式、自愿/强制属性和时空范围,认为标准的记录形式有文件、样品、图形符号、物理表达等多种形式;标准具有选择的自愿性和实施的强制性;标准在时空范围内是有限的。文章的结尾给出了理解标准化概念的框架。 相似文献
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目的 探索如何利用网络青年亚文化来推动包装年轻化。方法 在梳理品牌年轻化、包装年轻化和网络青年亚文化等概念的基础上,结合相关理论和案例,提出包装设计利用网络青年亚文化,来促进包装年轻化的原则和策略。结论 包装年轻化是品牌年轻化的重要手段,可以达到维持品牌年轻形象、改变品牌老旧形象、阻止品牌形象老化等目的。网络青年亚文化有助于促进包装年轻化。包装年轻化策略主要是挖掘包装的文化功能、传播功能和社交功能。网络青年亚文化驱动的包装设计应该遵循匹配性、社交性、娱乐性、创新性等原则。在全面分析品牌内部和外部情况的基础上,企业要不断探索符合自身特点的包装年轻化策略,并持续改进。其中,循序渐进、品牌联合、新品牌、包装延伸和品牌社群等是包装年轻化常见的有效策略。 相似文献
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K. V. Frolov N. A. Makhutov G. Kh. Khurshudov M. M. Gadenin 《Strength of Materials》2000,32(5):409-416
The evolution of approaches to the solution of machine dynamics and strength problems on the basis of determining static and dynamic nominal and local stresses of the operating load is discussed. It is shown how the material strength and plasticity characteristics, the cyclic strength characteristics in the high-cycle and low-cycle fatigue regions, the high-temperature long-term strength and creep characteristics, and the linear and nonlinear characteristics of fracture mechanics were sequentially used as the basic criterial parameters of the deformability and strength of structural materials. Particular emphasis was given to the results of studies on machine safety and catastrophe mechanics. Integrated approaches to the solution of strength and safety problems of potentially dangerous facilities (nuclear power stations, spacecraft complexes, aircraft, chemical plants, etc.) by analysis of all stages of their life cycle, including design, manufacture, testing, and operation, are discussed. 相似文献
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In recent years, the use of nanocomposite materials to functionalize surfaces has been investigated, taking advantage of the complementary properties of the nanocomposite constituents. Among this family of materials, ceramic-Ag coatings have been widely studied due to the large variety of functionalities that silver possesses and the possibility of tuning the coating’s practical features by selecting the proper matrix to support this noble metal. Therefore, this review focuses on the effects of silver nanoparticles on the functional properties of ceramic-Ag nanocomposites. The chemistry, structure, morphology and topography of the coatings are analyzed with respect to the changes produced by the silver nanoparticles’ distribution, amount and sizes and by altering production process variables. To offer a clear understanding of the functionalities of these materials, the optical, electrical, mechanical, tribological, electrochemical and biological properties reported in the last decade are reviewed, focusing on the ability to tune such properties by modifying the silver distribution, morphology and composition. In particular, the surface plasmon resonance, self-lubricating ability and antibacterial effect of silver are covered in detail, establishing their correlation with factors such as silver diffusion, segregation and ionization. 相似文献
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基于单因素实验,研究工艺参数对不同厚度聚甲醛(POM)微注塑制品屈服应力、弹性模量、断裂强度和断裂伸长率等力学性能指标的影响,并基于制品形态结构分析工艺参数对制品力学性能的影响机理。实验结果表明,随着注射速度的增大,1.0mm厚微制品的皮层厚度减小,过渡层厚度增加,结晶度增大,综合效应使得屈服应力、断裂强度和弹性模量增大,断裂伸长率减小;0.2mm厚微制品的皮层厚度占主导地位,其力学性能是由皮层的力学性能决定,皮层厚度先增大后减小使得屈服应力、断裂强度和弹性模量先增大后减小,断裂伸长率先减小后增大。随着熔体温度的升高,1.0mm厚微制品的分子链取向度减小,皮层厚度减小,收缩量增大,使得屈服应力、断裂强度和弹性模量减小,断裂伸长率增大;而0.2mm厚微制品的皮层减小,但过渡层增加,结晶度增大,且补料更充分,综合作用使得屈服应力、断裂强度和弹性模量增大,断裂伸长率减小。随着模具温度的升高,1.0mm厚微制品的皮层比例减小,结晶度增大,结晶度影响占主导,使得屈服应力、断裂强度和弹性模量逐渐增大,断裂伸长率减小;而0.2mm厚微制品的皮层厚度占主导,皮层厚度明显减小使得屈服应力、断裂强度和弹性模量减小,断裂伸长率增大。 相似文献
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通过使用波形测量手段和最小二乘直线拟合方法,对三角波信号的波峰、波谷、中值、幅度、频率、沿斜率、沿线性度、对称性等指标进行了精确评价,详细讨论了方法的实现过程以及有关技术问题,并对各项参数指标进行了不确定度分析。实验验证结果表明了该方法的有效性和实用性,该方法可应用到三角波信号源的性能指标评价中。 相似文献