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李凤臣 《华北科技学院学报》2002,4(4):60-62
站在我国改革开放前沿的宾馆业,如今面临“观念陈旧,管理落后,效益不佳”等诸多问题,客房“短期焊满,长期闲置”现象严重,经营处在“欲扩不可,欲维不能”的尴尬困境之中。走经营模式创新之路,实行宾馆代理制,是宾馆业摆脱困境局面的良方。 相似文献
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李凤臣 《华北科技学院学报》2001,(1)
企业为获取持久竞争优势和市场领导地位。总是在不断追求新的竞争手段和方式;服务在营销中的地位和作用日见突出,“服务经济时代”已经到来。 相似文献
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李凤臣 《华北科技学院学报》2002,4(1):45-47
变动成本法是管理会计中计算成本的方法,可以更加真实全面地反映生产管理中的实际情况。为了走出企业管理的盲区,应运用变动成本法计算成本,加强企业内部管理。 相似文献
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豫南桐柏山北部金银多金属矿带中有广泛发育的由正常沉积浅海相碎屠岩变质而成的变粒岩,这些变粒岩都有明显的变余碎屑结构(照片3)和变余构造。我们试图通过粒度分析的方法来追索其古沉积环境,虽然这种方法在沉积碎屑岩的岩相分析应用中很有效,但应用于相当角闪岩相的变粒岩还是初步尝试,不当之处,请同志们批评。 相似文献
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Direct numerical simulation of elastic turbulence and its mixing-enhancement effect in a straight channel flow
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In this paper,we present a direct numerical simulation(DNS) of elastic turbulence of viscoelastic fluid at vanishingly low Reynolds number(Re = 1) in a three-dimensional straight channel flow for the first time,using the Giesekus constitutive model for the fluid.In order to generate and maintain the turbulent fluid motion in the straight channel,a sinusoidal force term is added to the momentum equation,and then the elastic turbulence is numerically realized with an initialized chaotic velocity field and a stretched conformation field.Statistical and structural characteristics of the elastic turbulence therein are analyzed based on the detailed information obtained from the DNS.The fluid mixing enhancement effect of elastic turbulence is also demonstrated for the potential applications of this phenomenon. 相似文献
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针对石油井架结构长期服役在野外恶劣环境下,局部或整体损伤等缺陷常成为安全生产中的事故隐患。通过白噪声模拟随机环境激励,利用ANSYS有限元建模,对石油井架系统进行动力响应分析。研究结果表明:井架结构的振动模态为空间振动,同时各节点在白噪声激励下的动力响应规律基本一致,动力响应数据的获得可为损伤诊断研究提供输入数据,对提高井架承载能力检测与安全评估水平,具有重要的理论意义和实用价值。 相似文献
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The explicit compact difference scheme,proposed in Three-point explicit compact difference scheme with arbitrary order of accuracy and its application in CFD by Lin et al.,published in Applied Mathematics and Mechanics (English Edition),2007,28(7),943-953,has the same performance as the conventional finite difference schemes.It is just another expression of the conventional finite difference schemes. The proposed expression does not have the advantages of a compact difference scheme. Nonetheless,we can more easily obtain and implement compared with the conventional expression in which the coefficients can only be obtained by solving equations,especially for higher accurate schemes. 相似文献
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Characteristics and generation of elastic turbulence in a three-dimensional parallel plate channel using direct numerical simulation
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Direct numerical simulations(DNSs) of purely elastic turbulence in rectilinear shear flows in a three-dimensional(3D) parallel plate channel were carried out,by which numerical databases were established.Based on the numerical databases,the present paper analyzed the structural and statistical characteristics of the elastic turbulence including flow patterns,the wall effect on the turbulent kinetic energy spectrum,and the local relationship between the flow motion and the microstructures' behavior.Moreover,to address the underlying physical mechanism of elastic turbulence,its generation was presented in terms of the global energy budget.The results showed that the flow structures in elastic turbulence were 3D with spatial scales on the order of the geometrical characteristic length,and vortex tubes were more likely to be embedded in the regions where the polymers were strongly stretched.In addition,the patterns of microstructures' elongation behave like a filament.From the results of the turbulent kinetic energy budget,it was found that the continuous energy releasing from the polymers into the main flow was the main source of the generation and maintenance of the elastic turbulent status. 相似文献
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