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1.
Analytic expressions for the flow and pressure in a dead-end duct which has loss of fluid through a porous wall are developed. The presence of an obstruction or auxiliary fan at the end of the duct is included. In either case there is a maximum permissible length of duct. As the duct length approaches this maximum, the main supply fan power and flow increase dramatically. There is no recirculation within the duct when there is an obstruction at the end of the duct. If an auxiliary fan is used, there is always recirculation. However the use of an auxiliary fan can yield major savings in total power requirements. 相似文献
2.
心式铁心柱电力变压器油道位置设计计算 总被引:1,自引:1,他引:0
利用电力变压器铁心柱制造特点,针对铁心柱内插入油道的要求将其转化为半径为R的圆内插入一族平行线,这族平行线分圆面积为相等的带状区域这一问题,然后用MATLAB中的SOLVE()函数求解,从而得到了油道位置的准确数据,为变压器的设计制造提供了科学依据。 相似文献
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4.
This study aims to investigate the Graetz problem of Newtonian and viscoelastic fluid obeying Giesekus model using ANSYS Polyflow solver. The non‐isothermal flow in straight ducts of circular and noncircular cross‐sections under the constant heat flux boundary conditions is considered. The effect of the mobility parameter (α), fluid elasticity defined by Weissenberg number (We) and Reynolds number (Re) on the flow field, secondary flows, and the fully developed and developing Nusselt number along the ducts length are investigated for all geometries. The obtained results are of great importance for practical application in the polymer industries such as polymer melt. 相似文献
5.
针对某大型建筑内的小型超市,进行了纤维风管送风和散流器送风两种情况下气流组织的数值模拟。结果表明采用纤维风管垂直于货架布置的送风方式能有效避免货架对气流的阻挡,使气流顺利到达工作区,增强了超市空间温度和风速的均匀性。 相似文献
6.
GENOMIC HARDWIRING AND PHENOTYPIC PLASTICITY OF TERPENOID-BASED DEFENSES IN CONIFERS 总被引:8,自引:0,他引:8
Over evolutionary history, conifers have faced a myriad of threats from phloem- and xylem-feeding insects, defoliating insects, and fungal pathogens. Among the trees defenses, terpenoids appear to play a major role by harming, disabling, deterring, repelling, or otherwise reducing the fitness of potential invaders. Each of the three classes of terpenoids in conifers, monoterpenes, sesquiterpenes, and diterpenes, are composed of a large number of representative compounds. In most cases, the presence of a particular terpenoid compound in the oleoresin or volatile emissions from a specific conifer can be accounted for by the expression of one of many committed terpene synthase (TPS) genes. However, while each TPS may produce one or a few major products, many produce a variety of minor products with relatively constant component ratios in the product blends. TPS genes exist in conifers in large and functionally diverse, yet monophyletic, gene families. Within these gene families, new biochemical functions of TPS appear to have evolved by gene duplication and changes in the amino acid sequence of the enzymes active site. In addition, TPS genes may be differentially expressed prior to, during, and following attack by insects or pathogens. Thus, while the production of any particular terpenoid is hardwired into a conifers genome, these trees have the capacity to change the mixture of terpenoids in oleoresin secretions and volatile emissions. Anatomical changes may also accompany induced terpenoid production, supplementing the plasticity of the molecular and biochemical events. 相似文献
7.
许保彬 《玻璃钢/复合材料》2008,(4)
根据多年的生产经验及研究,对玻璃钢通风管道模具的制作工艺要点(如木型的处理、模具的糊制及表面处理)进行了较详细的分析介绍,可为通风管道制造高质量的玻璃钢产品提供一些参考。 相似文献
8.
A life cycle optimization model intended to potentially reduce the environmental impacts of energy use in commercial buildings is presented. A combination of energy simulation, life cycle assessment, and operations research techniques are used to develop the model. In addition to conventional energy systems, such as the electric grid and a gas boiler, cogeneration systems which concurrently generate power and heat are investigated as an alternative source of energy. Cogeneration systems appeared to be an attractive alternative to conventional systems when considering life cycle environmental criteria. Internal combustion engine and microturbine (MT) cogeneration systems resulted in a reduction of up to 38% in global warming potential compared with conventional systems, while solid oxide fuel cell and MT cogeneration systems resulted in a reduction of up to 94% in tropospheric ozone precursor potential (TOPP). Results include a Pareto-optimal frontier between reducing costs and reducing the selected environmental indicators. 相似文献
9.
浅析空调全热式交换器新风系统的经济性 总被引:1,自引:0,他引:1
详细比较了全热式交换器新风系统与传统外接冷热源新风系统在初投资与运行费用上的区别。 相似文献
10.