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航天应用的制冷机系统 总被引:3,自引:0,他引:3
介绍冷却4×22 元 Hg Cd Te 红外探测器的集成组件的斯特林制冷系统。这是一种单级的牛津型的斯特林制冷机。其特点是采用膜片弹簧支撑、音圈电机驱动、差动变压器的位移传感器和间隙动密封技术。制冷机的最低制冷温度43 K, 降温时间20 m in, 其压缩机功耗约30 W。制冷机系统采用双机屏蔽轴向对置排列, 以减小系统机械振动和对探测器的电磁干扰。制冷机通过柔性冷链(汇流排)冷却红外探测器组件。系统在80 K 时对探测器提供的冷量大于30 m W,制冷机功耗45 W。冷链温差为25 K, 探测器等效温度灵敏度02 K。 相似文献
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对脉管型斯特林制冷机用于普冷的可行性进行了分析研究。用实验的方法对脉管到斯特林制冷机和单纯的斯特林制冷机的性能进行了对比,得出了在245K以上温区脉管型斯特林制冷机的性能优于单纯的斯特林制冷机的重要结论.对小孔和脉管长度变化对脉管型斯特林制冷机性能的影响进行了讨论. 相似文献
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目的 立足番禺水色民俗艺术,分析当前番禺水色文创产品现状,深入挖掘番禺水色艺术元素及文化内涵,探索番禺水色岭南民俗艺术文创产品设计方法与案例。方法 综合运用层次分析法、符号分析法等方法,提炼番禺水色文化符号作为设计元素与生活产品相结合的视觉语言,设计既蕴含番禺水色艺术特色又兼具现代时尚元素的文创产品,并在实践中予以运用。结论 番禺水色是独具岭南地域特色的行为文化,通过对番禺水色艺术的造型、色彩、精神等元素进行梳理归纳,巧妙运用于灯具设计,为番禺水色文创产品融入消费者生活找到契合点。 相似文献
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McCave IN Kiefer T Thornalley DJ Elderfield H 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2005,363(1826):81-99
The SW Indian Ocean contains at least four layers of water masses with different sources: deep Antarctic (Lower Circumpolar Deep Water) flow to the north, midwater North Indian Deep Water flow to the south and Upper Circumpolar Deep Water to the north, meridional convergence of intermediate waters at 500-1500 m, and the shallow South Equatorial Current flowing west. Sedimentation rates in the area are rather low, being less than 1 cm ka(-1) on Madagascar Ridge, but up to 4 cm ka(-1) at Amirante Passage. Bottom flow through the Madagascar-Mascarene Basin into Amirante Passage varies slightly on glacial-interglacial time-scales, with faster flow in the warm periods of the last interglacial and minima in cold periods. Far more important are the particularly high flow rates, inferred from silt grain size, which occur at warm-to-cold transitions rather than extrema. This suggests the cause is changing density gradient driving a transiently fast flow. Corroboration is found in the glacial-interglacial range of benthic delta18O which is ca. 2 per thousand, suggesting water close to freezing and at least 1.2 more saline and thus more dense glacial bottom waters than present. Significant density steps are inferred in isotope stage 6, the 5e-5d, and 5a-4 transitions. Oxygen isotope data suggest little change by mixing in glacial bottom water on their northward path. Benthic carbon isotope ratios at Amirante Passage differ from glacial Southern Ocean values, due possibly to absence of a local productivity effect present in the Southern Ocean. 相似文献
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0.8~1微米分步重复投影光刻机中国科学院光电技术研究所承担的国家“八·五”科技攻关项目“0.8~1微米分步重复投影光刻机”,于1996年1月通过了国家验收,1996年11月至1997年4月在北京微电子中心按“0.8微米CMOS全套工艺”进行工艺考核... 相似文献
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合同能源管理在我国供热空调系统中的应用前景分析 总被引:1,自引:0,他引:1
针对我国的能源形势,分析了供热空调系统的节能潜力,介绍了具有很好发展前景的合同能源管理概念、方法和步骤,以及在我国实施过程中出现的问题及对策.以实际空调和供热工程的案例对合同能源管理的效益进行了分析,结果表明,合同能源管理是一种业主和合同能源管理公司双赢的模式,在我国供热和空调行业有广阔的应用前景. 相似文献
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EMC is an important part of the ever-changing world in which we now find ourselves. Society is increasingly dependent on radio, telecommunications and electronic products, but their use is only possible if the necessary EMC criteria are met. However the criteria of the last century will not necessarily be those required for the one that we have just entered. EMC is no longer a backwater of engineering where we can afford to leave the problems to the “experts”; it is and area where every engineer needs to become involved. Undoubtedly EMC has made significant strides forward during the past decade, but further progress is necessary if we are to ensure that we continue to enjoy a relatively interference-free environment in the years to come. This paper looks at the six major challenges that need to be tackled if we are to be successful in controlling EMC in the new millennium 相似文献
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Lauri Rautkari Callum A. S. Hill Simon Curling Zaihan Jalaludin Graham Ormondroyd 《Journal of Materials Science》2013,48(18):6352-6356
It has often been claimed that the equilibrium moisture content (EMC) of wood is controlled by the available hydroxyl group content and their accessibility, but this has not been proven. In the present study, the accessibility of the hydroxyl groups were analysed by deuterium exchange in a dynamic vapour sorption apparatus, and generally poor correlation with the EMC and hydroxyl group accessibility was found. Therefore, the role of the accessibility of wood hydroxyl groups in relation to exerting sole influence on the EMC is disputable. It is concluded that there has to be an additional mechanism to exercise control over the EMC in addition to hydroxyl group accessibility. 相似文献
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We describe our efforts to study and compare the ocean-color data derived from the Japanese Ocean Color and Temperature Scanner (OCTS) and the French Polarization and Directionality of the Earth's Reflectances (POLDER). OCTS and POLDER were both on board Japan's Sun-synchronous Advanced Earth Observing Satellite from August 1996 to June 1997, collecting approximately 10 months of global ocean-color data. This operation provided a unique opportunity for the development of methods and strategies for the merging of ocean-color data from multiple ocean-color sensors. We describe our approach to the development of consistent data-processing algorithms for both OCTS and POLDER and the use of a common in situ data set to calibrate vicariously the two sensors. Therefore the OCTS- and POLDER-measured radiances are bridged effectively through common in situ measurements. With this approach to the processing of data from two different sensors, the only differences in the derived products from OCTS and POLDER are the differences that are inherited from the instrument characteristics. Results show that there are no obvious bias differences between the OCTS- and POLDER-derived ocean-color products, whereas the differences due to noise, which stem from variations in sensor characteristics, are difficult to correct at the pixel level. The ocean-color data from OCTS and POLDER therefore can be compared and merged in the sense that there is no significant bias between two. 相似文献
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On combination of the equivalent material concept and J‐integral criterion for ductile failure prediction of U‐notches subjected to tension
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H.R. Majidi M.E. Golmakani A.R. Torabi 《Fatigue & Fracture of Engineering Materials & Structures》2018,41(7):1476-1487
The aim of the present research is to check the capability of the equivalent material concept (EMC) combined with the J‐integral failure criterion, called EMC‐J criterion, in predicting the load‐carrying capacity (LCC) of U‐notched ductile aluminium plates subjected to tension by considering the 2 moderate and large‐scale yielding regimes. For this purpose, first, a set of experimental results on LCC of 2 groups of thin U‐notched rectangular plates made of Al 7075‐T6 and Al 6061‐T6 are gathered from the recent literature. Then, because the Al 7075‐T6 and Al 6061‐T6 plates have ductile behaviour, EMC is employed to avoid performing elastic‐plastic failure analysis for LCC predictions. Up to now, different failure models in the context of the linear‐elastic notch fracture mechanics have been successfully utilized in combination with EMC for ductile failure prediction of notched members. However, this is the first time in this research that J‐integral, as a well‐known brittle failure criterion, is linked to EMC for predicting LCC of the U‐notched rectangular aluminium plates. Finally, it is shown that EMC‐J criterion can predict well the experimental results of tensile LCC. 相似文献
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Samura K Hashimoto S Kawasaki M Hayashida A Kagi E Ishiwata T Matsumi Y 《Applied optics》2002,41(12):2349-2354
Two optical methods, cavity ring-down spectroscopy and photoacoustic spectroscopy, are applied to the measurement of the isotope ratio 18O/16O in water-vapor samples with a Nd3+:YAG pumped-dye laser. The combination band of (2v1 + v3) in the 960-nm region of water molecules is investigated for two standard water samples, the Vienna Standard Mean Ocean Water and the Standard Light Antarctic Precipitation. The results demonstrate that the two methods have the potential of compact systems for in-situ measurements of H2O isotope ratio in the environment. 相似文献