铁路军事运输柔性捆绑加固器设计

为进一步提高军事装备铁路运输捆绑加固效率和运输安全性,针对现有加固器材存在的问题,从加固器适应性、可靠性和便利性等3个方面,分析铁路军事运输柔性捆绑加固器的设计需求;提出柔性织带和棘轮收紧器结构设计方案及其功能;论证铁路军事运输柔性捆绑加固器的技战术指标.     

岗位体验式教学法在雷达装备实践教学中的应用

针对雷达装备实践教学中演示式教学法对于学员能力的拓展和装备的综合运用等方面存在的问题,将岗位体验式教学法运用于雷达装备实践教学中.首先分析岗位体验式教学法的基本内涵;然后提出前期准备、场景设置、教学实施、交流研讨和总结讲评等5个方面的具体实施方法,进行实例分析;最后给出岗位体验式教学法的实施效果.教学实践结果验证了该方法的有效性.     

PREDICTION OF THE PROBABILITY OF SPHEROIDIZATION IN NODULAR CAST IRON BY PARAMETRIC DIAGRAM OF CHEMICAL BOND

<正> 本文试图从化学键理论出发,探讨石墨球化的规律。鉴于用键参数图法总结与化学键有关的规律性往往见效,故本文从球化剂元素和反球化元素在键参数图中的分布规律入手进行研究。 球化剂元素(或反球化元素)对石墨球化的影响应与该元素和C_(石墨)间的相互作用有关,其键参数函数写成如下形式:     

热压变形对灰口铸铁石墨形态的影响

研究了灰口铸铁(HTl50)在900℃大压下量塑性变形后石墨的分布形态，结果表明：随着压下量的增加，石墨片逐渐趋于平行分布；变形过程中发生了碳的回溶，同时伴随着石墨片的断裂；石墨片体积分数及片间距随压下量的增加而逐渐减少。     

有限元方法在离心机转鼓强度分析中的应用

在回顾以往转鼓强度分析的基础上 ,指出了目前转鼓有限元应力分析所存在的问题 ,给出了提高计算精度和保证模拟有效性的注意事项 ,并探讨了转鼓强度评定准则     

Packed-microtubes model for flowthrough chromatography of protein

A mathematical model for flowthrough (perfusion) chromatography, namely packed-microtubes (PMT) model, has been proposed for a column packed with biporous (BiP) anion exchanger in which the mesopores and flowthrough pores are created with liquid and solid porogens, respectively. The model is established based on the assumption that the BiP particle is made up of packed microtubes. Bovine serum albumin (BSA) is used as a model protein and three kinds of anion exchangers (i.e., mesoporous, macroporous and BiP resins) are used as adsorbents to determine the model parameters and to evaluate the model. Adsorption equilibrium and finite bath experiments are performed to determine the adsorption isotherms and kinetics parameters. Both the bound amounts of the protein on the surface of the mesopores and macropores are experimentally determined and taken into account in the mathematical model. With all the model parameters determined by independent experiments or calculated from available correlations, model simulations are performed and compared with the experimentally determined breakthrough profiles of the BiP column. It is found that the model predictions agree reasonably well with the experimental data obtained under various conditions and the PMT model fit experimental data better than the modified double linear driving force (LLDF) model proposed by Leitão and Rodriogues (1999. Biochemical Engineering Journal 3, 131) in which the adsorbent particle is considered to be made up of packed microparticles. The results indicate that the PMT model is more reasonable for this kind of BiP adsorbent.     

Security concepts for the dynamics of autonomous vehicle networks

The secure operation of autonomous vehicle networks in the presence of adversarial observation is examined, in the context of a canonical double-integrator-network (DIN) model. Specifically, we study the ability of a sentient adversary to estimate the full network’s state, from noisy local measurements of vehicle motions. Algebraic, spectral, and graphical characterizations are provided, which indicate the critical role of the inter-vehicle communication topology and control scheme in achieving security.     

Propylene epoxidation in a microreactor with electric heating

Gas phase propylene epoxidation on gold catalysts has attracted wide attention from industry and academia due to its high selectivity. However, it suffers from low propylene conversion and rapid catalyst deactivation. Experiments showed that propylene conversion could be increased by raising H₂, O₂, or C₃H₆ concentration in the feed, but the feed compositions were within the explosion limit. It was also shown that the activity of the used catalyst could be fully recovered, but the regeneration temperature was 280 °C, much higher than that for reaction. Therefore a microchannel reactor was devised to suppress explosion and was constructed with Fecralloy, to raise the temperature rapidly for catalyst regeneration by electric heating. In two minutes the temperature of the reactor could be raised from 50 to 300 °C. Catalysts were coated on the alloy belt by dip coating, and the performance of the reactor was evaluated under different operating conditions. Results showed that in the microreactor the overall reaction rate was controlled mainly by the intrinsic reaction rate, and also influenced by film diffusion to a certain extent. The deactivated catalyst was regenerated in the microchannel reactor and the activity was fully recovered.     

Relationship of threshold diameter and Darcean permeability in unconsolidated porous structures

Experiment was conducted on the threshold pressure for atmospheric air through unconsolidated narrow size distributed mini sphere and sand particles at low flow rates. The threshold diameter calculated from measured threshold pressure showed that it does not follow the traditional similarity theory. This is consistent with our experiment on accurate permeability measurement, and can be explained as a result of gas slip flow within such micro pore structure. Our current work tend to find the method to predict the permeability-threshold pressure relationship for unconsolidated porous structures.     

Reaction kinetics study of asymmetric polymer-polymer interface

In this study, the reaction kinetics of asymmetric polymer-polymer interface was experimentally and theoretically studied. A new rheological method correlating the change of rheological property of reactive system with the conversion of the in situ formed copolymers was applied to study the reaction kinetics of PBT/epoxy reactive system. Then, the new method was proved to be useful by comparing its results with that obtained from the conventional endgroup determination method. Moreover, the conversion of PBT/epoxy reactive system from rheological method could be well fitted by the numerical analysis, from which the kinetic constant and the diffusion constant of epoxy in PBT could be determined simultaneously.