双效吸收式制冷系统稳态仿真研究

本文采用系统仿真中常用的研究方法,建立了双效溴化锂吸收式制冷系统的稳态集中参数仿真模型,编制了相应的仿真程序,并通过仿真结果与实验数据的比较,证明该仿真模型是比较可靠的.     

聚氨酯基pH/温度敏感性水凝胶的结构形态

通过阴离子型端丙烯酸酯基聚氨酯(UAA)与N-异丙基丙烯酰胺(NIPAAm)的共聚交联反应,制备了pH/温度敏感性水凝胶,分析了水凝胶的结构形态及溶胀水的状态.结果表明,凝胶相结构均匀,随聚氨酯含量的降低,凝胶的骨架变得松散,并且孔道结构增大,导致溶胀凝胶中不可冻结水含量及凝胶强度的降低.     

由状态变量识别板梁桥上移动荷载

将板梁桥等效为正交异性板,车辆等效为等间距常速度在正交异性板上移动的一组荷载。根据弹性板理论、HALMITON'S原理和模态叠加原理,得到了系统状态方程,并基于规则化技巧推导了状态空间移动荷载识别方法。数值模拟和试验结果表明,该方法用挠度或应变识别车辆的轴重和轮载都是有效、可行的。     

陶瓷基复合材料伪半固态触变成形及其在卫星角框件中的应用

提出了陶瓷基复合材料伪半固态成形工艺,并应用该工艺制备了30%(体积分数)Alp/SiCp复合材料卫星角框件.通过金相分析、拉伸等实验方法验证该工艺的可行性.结果表明,该工艺成形的零件微观组织比较均匀;硬度较高,HV可达到6.43GPa;应变(ε)约为0.5%;抗拉强度(σt)约为300MPa.     

模拟空间状态下的粉末冶金摩擦材料性能

研究了用粉末冶金方法生产的非金属含量较高的摩擦材料在模拟空间状态下的摩擦磨损性能。重点探讨了材料中非金属组元(特别是摩擦组元、润滑组元)对材料的摩擦性能及稳定度的影响。结果表明在模拟空间状态下, 无论是铁基还是铜基, 或是Fe/Cu基的摩擦材料仍然遵循在大气状态下的规律。研究结果表明除宇宙射线粒子的影响未考虑外, 模拟空间状态下摩擦性能最稳定的是具有一定润滑性能, 且非金属成分的体积分数比较高的铜基粉末冶金摩擦材料。     

2004年中国钼工业发展报告

从2004年中国钼工业经济运行情况、产业结构、市场及价格、对外贸易等几个方面，阐述了2004年中国钼工业发展现状，并对2004年中国钼工业经济运行状况进行了分析，指出了当前中国钼工业发展中存在的突出问题。     

120 mm×120 mm结晶器振动参数的优化

分析了120 mm×120 mm断面结晶器溅钢的主要原因,通过优化结晶器的振动参数,消除了结晶器溅钢,漏钢现象,脱模情况有所改观,取得了良好的效果.     

Viscous effect at an orthotropic micropolar boundary surface

Steady state responses at viscous fluid/ orthotropic micropolar solid interfaces to moving point loads have been studied. An eigenvalue approach using the Fourier transform has been employed to solve the problem. The displacement, microrotation and stress components for the orthotropic micropolar solids so obtained in the physical domain are computed numerically by applying numerical inversion technique. Viscosity and anisotropy effects on normal displacement, normal force stress and tangential couple stress have been shown graphically for a particular model. Some special cases of interest have been presented.     

Thermodynamic Properties of Methanol in the Critical and Supercritical Regions

The isochoric heat capacity of pure methanol in the temperature range from 482 to 533 K, at near-critical densities between 274.87 and 331.59 kg· m⁻³, has been measured by using a high-temperature and high-pressure nearly constant volume adiabatic calorimeter. The measurements were performed in the single- and two-phase regions including along the coexistence curve. Uncertainties of the isochoric heat capacity measurements are estimated to be within 2%. The single- and two-phase isochoric heat capacities, temperatures, and densities at saturation were extracted from experimental data for each measured isochore. The critical temperature (T_c = 512.78±0.02K) and the critical density (ρ_c = 277.49±2 kg · m⁻³) for pure methanol were derived from the isochoric heat-capacity measurements by using the well-established method of quasi-static thermograms. The results of the C_VVT measurements together with recent new experimental PVT data for pure methanol were used to develop a thermodynamically self-consistent Helmholtz free-energy parametric crossover model, CREOS97-04. The accuracy of the crossover model was confirmed by a comprehensive comparison with available experimental data for pure methanol and values calculated with various multiparameter equations of state and correlations. In the critical and supercritical regions at 0.98T_c≤ T ≤ 1.5T_c and in the density range 0.35ρ_c ≤ ρ leq 1.65 ρ_c, CREOS97-04 represents all available experimental thermodynamic data for pure methanol to within their experimental uncertainties.     

Effect of temperature and α-irradiation on gas permeability for polymeric membrane

In the present study the polyethersulphone (PES) membranes of thickness (35 ±2) μm were prepared by solution cast method. The permeability of these membranes was calculated by varying the temperature and by irradiation of α ions. For the variation of temperature, the gas permeation cell was dipped in a constant temperature water bath in the temperature range from 303–373 K, which is well below the glass transition temperature (498 K). The permeability of H₂ and CO₂ increased with increasing temperature. The PES membrane was exposed by a-source (₉₅Am₂₄₁) of strength (1 μ Ci) in vacuum of the order of 10⁻⁶ torr, with fluence 2.7 × 10⁷ ions/cm². The permeability of H₂ and CO₂ has been observed for irradiated membrane with increasing etching time. The permeability increases with increasing etching time for both gases. There was a sudden change in permeability for both the gases when observed at 18 min etching. At this stage the tracks are visible with optical instrument, which confirms that the pores are generated. Most of pores seen in the micrograph are circular cross-section ones.