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81.
大小样品在液氮中的淬冷沸腾换热比较研究 总被引:1,自引:1,他引:0
分析了大小样品在液氮中的淬冷沸腾换热特性。大小样品的淬冷沸腾换热有着明显的差别,小样品的热流密度比大样品的明显高得多。小样品的淬冷沸腾有一起始段,其温降高达60K。从实验结果还可以看到,小样品的Leidenfrost点和临界热流点对应的壁面过热度明显比大样品的高。最后还分析了样品直径对临界热流密度的影响。 相似文献
82.
83.
Exact solution of elasto-plastic stresses in a metal-matrix composite beam of arbitrary orientation subjected to transverse loads 总被引:1,自引:0,他引:1
An analytical elasto-plastic stress analysis is presented for a metal-matrix composite beam of arbitrary orientation subjected to a single transverse force applied to the free end of the beam and a uniformly distributed load. The material is assumed to be perfectly plastic in the elasto-plastic solution. A composite consisting of stainless-steel-reinforced aluminum was produced for this work. Sample problems are given for various orientation angles. Elastic, elastoplastic and residual normal and shear stresses are calculated. The location of the elasto-plastic boundary of the beam is obtained according to the x coordinates of the beam. 相似文献
84.
Douglas Walton 《Artificial Intelligence and Law》2006,14(3):177-239
In this paper it is shown how tools developed in argumentation theory and artificial intelligence can be applied to the development
of a new dialectical analysis of the speech act of making a proposal in a deliberation dialogue. These tools are developed,
modified and used to formulate dialogue pre-conditions, defining conditions and post-conditions for the speech act of making
a proposal in a deliberation dialogue. The defining conditions set out what is required for a move in a dialogue to count
as the making of a proposal by one of the parties. What is required are the conditions that (1) the move fit the requirements
of the argumentation scheme for practical reasoning, and (2) the premises are propositions describing common goals of both
parties or propositions that they reasonably consider means to achieve these goals. The analysis goes beyond the standard
speech act approach by specifying not only the normative requirements for making a well-formed proposal, but also the requirements
for responding to it by questioning or criticizing it, and the requirements for defending it. 相似文献
85.
The mechanisms governing the solubilizing interactions between zwitterionic/anionic mixed surfactant systems at different
molar fractions of the zwitterionic surfactant (Xzwitter) and neutral or electrically charged unilamellar liposomes were investigated. The mixed systems were formed by N-dodecyl-N,N-dimethylbetaine
and sodium dodecyl sulfate in the presence of piperazine-1,4-bis-(2-ethanesulfonic acid) buffer at pH 7.20. Unilamellar liposomes formed by egg phosphatidylcholine, in some cases together
with stearylamine or phosphatidic acid, were used. Solubilization was detected as a decrease in static light-scattering of
liposomes. Two parameters were regarded as corresponding to the effective surfactant/lipid molar ratios (Re) at which the
surfactant system (i) saturated the liposomes, Resat, and (ii) led to a total solubilization of liposomes, Resol. From these parameters the bilayer/aqueous medium surfactant partition coefficients for the saturation (Ksat) and complete bilayer solubilization (Ksol) were determined. When Xzwitter was 0.40, The Re and K parameters showed a maximum, whereas the critical micellar concentration (CMC) of these systems exhibited
a minimum, regardless of the electrical charge of bilayers. Given that the ability of the surfactant systems to saturate or
solubilize liposomes is inversely related to the Resat and Resol parameters, these capacities appear to be directly correlated with the CMC of the mixed systems. The similarity of both Ksat and Ksol (particularly for Xzwitter=0.2–0.8) suggests that a similar partition equilibrium governs both the saturation and the complete solubilization of bilayers,
the free surfactant concentration (Sa,Sb), remaining almost constant with similar values to the CMC for each mixed system studied. 相似文献
86.
水利工程排涝减灾效益分析与计算 总被引:2,自引:0,他引:2
在分析涝灾成因特点基础上对涝灾进行了重新定义,在研究涝灾损失及 排涝效益时引入了临界降雨量的概念,从而奠定了水利工程排涝减灾效益分析与计算的理论基础,并给了效益计算的一般计算模型。 相似文献
87.
The proposed mode of consideration of the steel-concrete interaction (Part I) is applied to real-life engineering structures. Two structures recently investigated numerically at Vienna University of Technology are considered: (1) the reinforced concrete (RC) cooling tower III Ptolema?s SES (Greece) and (2) a part of the shotcrete tunnel lining installed at the Lainzer tunnel (Austria). In both examples, the uniaxial fracture criterion used in Part I is replaced by the maximum stress (Rankine) criterion. Together with the Drucker-Prager criterion, which is used for the simulation of compressive failure of concrete/shotcrete, it defines the space of admissible stress states in the framework of multisurface plasticity. For the simulation of early-age fracture of shotcrete, consideration of the steel-concrete interaction presented in Part I of this paper is extended towards young shotcrete. Similar to the benchmark problem investigated in Part I of this paper, several analyses with different degrees of consideration of the steel-concrete interaction are performed. The obtained results give insight into the influence of the steel-concrete interaction on the load-carrying behavior of the investigated structures. 相似文献
88.
89.
90.
为研究海上风电结构在复杂的海洋环境中承受环境荷载(风、波、冰、流)的联合作用时,结构产生的剧烈的动力响应问题。文章以三脚架基础海上风电结构为研究对象,采用ANSYS有限元软件建立其整体模型并进行荷载(风、波、流和风、冰、流)联合作用下的静力校核,通过对环境荷载联合作用下的三脚架基础海上风电结构进行瞬态分析,掌握其动力响应的特性及规律。结果表明:三脚架基础结构的一、二阶自振频率均为0.285Hz,在所选风机允许的频率范围内,可以保证整体结构不会与风机转动发生共振;风荷载在风、波、流荷载联合作用下主导控制结构响应的稳态波动,冰荷载在风、冰、流荷载联合作用下主导控制结构的稳态振动过程;塔筒顶端呈现的位移和加速度响应均远大于三脚架基础顶端;环境荷载联合作用下结构动力响应是环境荷载单独作用下动力响应叠加的结果。 相似文献