包覆硝酸铵发射药吸湿性和安定性研究

为研究包覆硝酸铵(AN)发射药的吸湿问题,用硝化棉(NC)对不同AN含量的AN发射药进行了不同层数的包覆,然后对未包覆和包覆试样进行了平衡干燥器法吸湿测试和真空安定性试验。结果表明:在温度为30℃、相对湿度为90%的条件下,AN发射药的吸湿量随着AN含量的增加而增加;包覆层有效抑制了吸湿性,提高了AN发射药的安定性。     

变燃速发射药的燃烧性能

介绍了变燃速发射药的原理和实现方法。内层采用高燃速发射药．外层为低燃速发射药．从而达到变燃速的目的;分析了双层结构变燃速发射药的密闭爆发器燃烧性能及30mm火炮内弹道试验结果。与高分子包覆单基发射药相比,双层结构变燃速发射药具有较好的燃烧渐增特性和明显的低温度系数效果。     

新型硝基胍发射药研究

研究了一种含1,5-二叠氮基-3-硝基氮杂戊烷(简称DIANP)的硝基胍发射药,与M30硝基胍发射药火药力相近,烧蚀量仅为M30发射药的85%左右,力学性能有较大幅度的提高.     

六硝基芪对硝胺发射药燃烧性能的影响

加入２,２′,４,４′,６,６′－六硝基均二苯基乙烯（ＨＮＳ,六硝基芪）会使硝胺发射药ＲＨＤ６在不同初温下的ｐ－ｔ曲线彼此靠近,燃速温度系数降低。中止实验表明,ＲＨＤ６燃面对燃气生成速率具有补偿作用。ＨＮＳ使ＲＨＤ６中ＮＮＣ２主放热峰的活化能降低。     

程序控制燃烧发射药的概念和原理

从提高发射药燃烧渐增性和提高发射装药总能量角度,提出了一种新概念发射药及装药--程序控制燃烧发射药及装药.通过总结和归纳大量密闭爆发器和内弹道试验结果,得到了3个经验公式.根据经验公式可推断出高初速发射装药应同时具备高能量和高燃烧渐增特性,验证了程序控制燃烧发射药概念原理上的正确性.     

EI发射药的燃烧特性

为研究EI发射药的燃烧性能,基于EI发射药的制备过程及药形结构特征,对EI发射药的浸渍层分布、燃烧过程中药型尺寸及能量特性的变化进行了理论分析和实验验证.建立了EI发射药的燃速计算数学模型.制备了NG浸渍量分别为10％和15％的EI-1和EI-2样品.进行了密闭爆发器试验、显微切片照相.结果表明,NG浸渍量为15％时,火药力提高了10.14％,浸渍深度为0.168 mm;根据实验数据计算EI发射药的u-p曲线,150 MPa前EI发射药的燃速高于单基发射药,在150 MPa后两者重合;由L-B曲线知EI-2发射药的燃烧渐增性较好.只要NG浸渍量和聚酯浸渍量配比合适,EI发射药的火药力和燃烧渐增性在一定范围内可以同步增加.     

窄通道杆状发射药内孔燃气流动数值模拟

运用合理的简化假设,建立杆状发射药内孔通道燃气流动模型,利用Fluent软件求解器对长径比为40的某一特定单孔杆状发射药燃气在内孔的流动过程进行了数值模拟,在给定初始压力和温度的条件下模拟内孔燃气的速度分布及压力分布,并进行分析。结果表明,径向由孔中心到孔壁,燃气流速逐渐减小,压力逐渐增大;轴向燃气流速先逐渐减小,压力先逐渐增大,在10mm处突然形成速度和压力的震荡波,并随时间沿轴向传递,5ms后速度趋于平稳波动,压力整体保持波动并持续上升,但各点压力最终都保持稳定。     

高渐增性发射药研究进展

列举出发射药燃烧渐增性判断的方法,阐述了燃速渐增性发射药、燃面渐增性发射药、变燃速发射药技术的实现方式。对这3种方式进行对比分析,表明变燃速发射药在燃烧渐增性实现上有较大的优势。     

由密闭爆发器实验数据分析变燃速发射药的燃烧渐增性

为进一步研究变燃速发射药的燃烧渐增性,提出了一种利用密闭爆发器实验数据描述发射药能量释放规律的数学物理模型.通过密闭爆发器实验,研究了一种中心开孔式双层硝胺变燃速发射药试样的燃烧渐增性.结果表明,所提出的数学物理模型可以用来定量地判断发射药燃烧的渐增性强弱;所研制的硝胺发射药显示出了渐增性燃烧的特点,并且可以通过调节配方和药型尺寸,达到调节控制其燃烧渐增性的效果.     

压力补偿滴头内流场的数值模拟

压力补偿滴头流道狭窄,常规手段难以满足流场测试要求.基于计算流体动力学理论的数值仿真研究流道内流体流动是一个行之有效的方法,利用N-S(Navier-Stokes)方程描述滴头内流场,建立流体流动模型,通过对模型求解得到流场压力、速度分布,使流场中的复杂流动"可视化",减少实物实验的次数,实现滴灌滴头低成本、高效率开发.     

A Simple Gradient Maker

Abstract

A sugar gradient was formed directly in a centrifuge tube by means of a celluloid cone. This simple system does not require any pump or mixing reservoir.     

The Effect of Nonuniform Emitter Sheet Resistance on PERC Solar Cell Performance

Silicon - The aim of this research work is to study the effects of non-uniform emitter sheet resistance on the performance of PERC solar cells. For this purpose, we used different simulation...     

不同表面复合速率情况下IBC太阳电池发射区半宽度研究

利用TCAD半导体器件仿真软件对N型插指背接触(Interdigitated Back Contact,IBC)单晶硅太阳电池发射区半宽度进行研究,全面系统地分析了在不同背表面复合速率的情况下,发射区半宽度对IBC太阳电池短路电流密度(JsC)、开路电压(VOC)、填充因子(FF)及转换效率(Eff)的影响.结果表明:随着背表面复合速率的增大,对于不同发射区半宽度的情况,IBC太阳电池JSC、VOC、FF及Eff均显著降低.当背表面复合速率一定时,发射区半宽度越大,JSC、VOC越高,而FF越低.随着发射区半宽度的增大,IBC太阳电池Eff呈现先增大后减小的变化特点.当背表面复合速率较小(50～500 cm/s)时,最优的发射区半宽度为800 μm.当背表面复合速率较高(≥5000 cm/s)时,最优的发射区半宽度为1200 μm.     

Single-photon Transistors Based on the Interaction of an Emitter and Surface Plasmons

A symmetrical approach is suggested (Chang DE et al. Nat Phys 3:807, 2007) to realize a single-photon transistor, where the presence (or absence) of a single incident photon in a ‘gate’ field is sufficient to allow (prevent) the propagation of a subsequent ‘signal’ photon along the nanowire, on condition that the ‘gate’ field is symmetrically incident from both sides of an emitter simultaneously. We present a scheme for single-photon transistors based on the strong emitter-surface-plasmon interaction. In this scheme, coherent absorption of an incoming ‘gate’ photon incident along a nanotip by an emitter located near the tip of the nanotip results in a state flip in the emitter, which controls the subsequent propagation of a ‘signal’ photon in a nanowire perpendicular to the axis of the nanotip.     

焦化余热的梯级利用

利用焦化生产过程中的余热进行冬季采暖,可将采暖后的余热供蔬菜大棚利用,再回收低品质热能,实现热量梯级利用。     

梯度层数对聚氨酯／环氧梯度互穿网络聚合物力学性能的影响

设计了一种新的梯度组分分布数学模型，采用梯度因子和梯度层数控制梯度组分的分布，并采用逐层浇铸的方法制备了不同层数的EP／PU梯度互穿网络聚合物（IPN）材料；测试了材料的拉伸性能、弯曲性能以及冲击性能；研究了梯度层数变化对这些性能的影响，并同普通IPN的性能进行了对比。研究结果表明，在相同质量比和梯度因子情况下，梯度层数越多，拉伸强度和冲击强度越高，弯曲强度越低。梯度IPN的拉伸强度和冲击强度均高于普通IPN，弯曲强度低于普通IPN。     

Gradient polymers by diffusion polymerization

Gradient polymers are multicomponent polymers whose structures or compositions are not macroscopically homogeneous, but vary as a function of position in the sample. One method to prepare such polymers is by diffusing a guest monomer into a host polymer and then polymerizing the monomer in position to retain the concentration gradient created by the diffusion. One series of such type of materials was prepared by diffusing acrylonitrile into polystyrene. The gradient profile was determined by analyzing the nitrogen content in succeeding layers of the sample. These gradient polymers exhibit improved resistance to hydrocarbon solvents. The second series of gradient polymers was made by diffusion of methyl acrylate into poly(methyl methacrylate). These materials are shown to possess substantially increased fracture strain. Eyring's stress-biased activated rate theory of yielding was used to rationalize the observed toughening effect in gradient polymers.     

Templating Surfaces with Gradient Assemblies

One of the most versatile and widely used methods of forming surfaces with position-dependent wettability is that conceived by Chaudhury and Whitesides more than a decade ago [Science 256, 1539 (1992)]. In this paper we review several projects that utilize this gradient-forming methodology for: controlled of deposition of self-assembled monolayers on surfaces, generating arrays of nanoparticles with number density gradients, probing the mushroom-to-brush transition in surface-anchored polymers, and controlling the speed of moving liquid droplets on surfaces.