Application of neural networks to identification of nonlinear characteristics in cushioning packaging

The structural neural network method is applied to the identification of nonlinear characteristics of cushioning liners in cushioning packaging. The simulated results on the two typical cushioning liner models show that the nonlinear characteristics can be identified perfectly.     

钢质薄壁气缸套超声珩磨的研究

作者作用自行研制的立式超声珩磨装置对钢质薄壁气缸套本体进行了超声珩磨试验，分别以表面粗糙度和珩磨效率为指标对超声珩磨油石进行了正交试验，确定了超硬磨料，粒度和结合剂对表面粗糙度和珩磨效率的影响顺序，试验结果表明，超声珩磨钢质薄壁气缸套可提高珩磨效率１－３倍，表面粗糙度Ｒａ可达０．５－２．１μｍ，超声珩磨解决了钢质薄壁气缸的加工难题，开辟了一条高效率珩磨加工软钢的途径。     

大口径毛细管柱拟柱上进样衬管的研制

进样口衬管是气相色谱仪进样口的重要部件，样品的分离效果、定量的可靠性与重现性都与进样方法及进样口衬管息息相关。岛津GC—17A所配的大口径毛细管柱的直接进样衬管死体积较大，为克服衬管死体积引起进样谱带展宽的缺点，厂商建议使用的线速度远高于大口径平均最佳线速度，由于国内大多数色谱用户使用N2作载气，这就必然是在牺牲更多柱效的情况下进行色谱分析。柱上进样方式是弥补上述缺点的有效方法。但无论是柱上（on column）进样或改进的柱上（at column）进样装置均较复杂。我们研制了一种简易的（热）拟柱上进样衬管，可以直接安装在色谱仪器的填充柱进样口，在最佳线速度下分析样品，充分发挥大口径柱的柱效，分离效果基本与分流进样一样。     

STUDIES ON COMBUSTION BEHAVIOR OF NR/MMT NANO-COMPOSITES BY CONE CALORIMETER

The NR/modified montmorillonite(EMT)nano-composites were prepared by mechanical mixing and reacting in situ with glycidyl methacrylate.Under 30 kW.m~(-2)of heat flux,the combustion behavior of the nano-composites was studied with cone calorimetry,and PHRR,THR,EHC,TSR and MLR were tested.The results showed that the nano- composite had improved mechanical properties and flame retardance properties,and to some extent,the nano-composite had smoke suppress effect.Compared with pure NR,the PHRR,EHC and SPR of the nano-composite reduced by 34%,21% and 16.8%,respectively.     

On the global well‐posedness of discrete Boltzmann systems with chemical reaction

We study an initial‐boundary value problem in one‐space dimension for the discrete Boltzmann equation extended to a diatomic gas undergoing both elastic multiple collisions and chemical reactions. By integration of conservation equations, we prove a global existence result in the half‐space for small initial data N₀∈??∩L¹. Copyright © 2005 John Wiley & Sons, Ltd.     

Cumulative compressibility effects on slow reactive dynamics in turbulent flows

Reactions in turbulent flows, chemical reactions or combustion, are common. Typically reaction time scales are much shorter than turbulence timescales. In biological applications, as it is the case for bacterial and plankton populations living under the influence of currents in oceans and lakes, the typical lifetime can be long and thus can fall well within the inertial range of turbulence time scales. Under these conditions, turbulent transport interacts in a very complex way with the dynamics of growth and death of the individuals in the population. In the present paper, we quantitatively investigate the effect of the flow compressibility on the dynamics of populations. Small effective compressibility can be induced by several physical mechanisms, such as, e.g., by the density mismatch, by a small but finite size of microorganisms, and by gyrotaxis (an interaction between swimming and shear). We report, for the first time, how even a tiny effective compressibility can produce a dramatically large effect on global quantities like the carrying capacity of the ecosystem. We interpret our findings by means of a cumulative effect made possible by the long replication times of the organisms with respect to turbulence time scales. A statistical quantification of the fluctuations of population concentration is presented.     

铅对粉末药型罩性能的影响

 为了研究铅粉对钨铜粉末药型罩性能的影响,在钨铜药型罩原配方的基础上,添加5%～20%的铅粉进行实验研究。实验结果表明：添加铅粉可以减少粉末药型罩的孔隙度;随着铅粉添加量的增加,射流的侵彻深度和入口孔径均增加,当铅含量为10%～15%时,侵彻深度和入口孔径达到最佳值,侵彻深度可以提高30%,再添加铅粉,侵彻深度和入口孔径均随之下降。从粉末药型罩成型以及射流的形成、拉伸及侵彻靶板等方面,对造成这种现象的原因进行了详细分析,获得了铅对粉末药型罩性能影响的一些机理认识。研究结果为铅粉代替铋粉添加到钨铜粉末药型罩以提高其侵彻性能提供了一定的理论依据。     

杆式射流形成的数值模拟研究

利用数值仿真软件LS-DYNA3D,通过数值模拟方法研究了药型罩压跨、射流的形成、延伸和失稳断裂的全过程,数值模拟结果与实验结果吻合较好,得到了一套实用的数值模拟方法及材料模型参数,定性分析了大锥角的药型罩压垮过程,对形成杆式射流的药型罩结构设计具有一定借鉴意义。