Mechanism and laws of combustion of composite solid propellants with a coolant

The model of combustion of a composition consisting of a quasi-homogeneous composite propellant (matrix) and coolant particles is considered. The model is based on the leading role of exothermal decomposition of the matrix and on the cooling effect of the second component by virtue of transverse heat transfer between the components in the condensed and gas phases. Formulas for combustion characteristics (temperature, burning rate, its sensitivity to pressure, and initial temperature) are derived and analyzed. The calculated dependences of these characteristics on pressure, particle size, concentration, and thermal effects of decomposition of the components show that transitional regimes with a stronger dependence of the burning rate on pressure than that of the initial propellant are reached in a certain range of parameters. An algorithm is proposed, and a parametric identification of the model on the basis of experimental data is performed. __________ Translated from Fizika Goreniya i Vzryva, Vol. 43, No. 6, pp. 51–60, November–December, 2007.     

高强变形铝合金的研究现状和发展趋势

总结了国内外关于高强铝合金的发展历程，探讨了超高强铝合金的强韧化机制及研究现状。对比分析了相关的热处理工艺对超高强铝合金的性能的影响。展望了超高强铝合金今后的发展方向和发展目标。国内外超高强铝合金研制基本上是沿着高强度、低韧性→高强度、高韧性→高强度、高韧性、耐腐蚀方向发展；随之的热处理状态开发则是沿着T6→T73→T76→T736（T74）→T77方向进展；在合金设计方面的特点是合金化程度越来越高，Fe和Si等杂质含量越来越低，微量过渡族元素添加越来越合理。改进合金成分、改善合金制备工艺和开发新型的热处理工艺是提高超高强铝合金性能的重要发展方向和途径。     

7xxx系铝合金热处理的进展

7xxx系合金是基于Al-Zn-Mg（-Cu）系的可热处理的锻铝合金，广泛应用于高性能航空结构和运输部件。除了受成分、铸造和形变热处理影响外，材料性能的平衡明显受到其所经历的热处理方式的影响。描述了均匀化、固溶处理、淬火、时效对7xxx系高强合金组织和性能的影响。总结了在Monash大学进行的有关厚板产品的生产工艺，包括从均匀化到最终的时效处理，以及通过控制微观组织特征，比如弥散体、粗粒子、精细析出相、晶粒结构和晶界特征，来实现组织与性能的平衡。重点陈述了相关方法，如通过高温热处理溶解不需要的粗粒子、基于连续冷却析出行为的淬火敏感性变化、通过实验与建模来研究时效包括一步时效、两步时效、三步时效。对每种情况下的组织与性能都进行研究。     

浅谈基于画面云实现高清频道的监测

在当今“三融合“的大背景下,电信IPTV不断进入电视行业,同时OTT也不断冲击视频媒体.新媒体与多媒体、互联网思维模式形成的多种格局复杂,使得必须实现网络改造的双向化有线电视进入发展的艰难时期.主要根据云南广电网络在无线“屏屏通”楚雄试点工作经验的基础上,就实现“屏屏通”发展进行技术交流.简述了“屏屏通”系统基本的组成、优势和收视状况,让有线电视也能够在无线发展上有一个新的突破.通过有线电视节目集成前端和双向互动平台管理的两大优势,探索实现全省光缆+公共WiFi方式在小屏幕上收看数字电视、无线上网查询信息等新功能.     

合金成分与热处理对6xxx系铝合金力学性能的影响

研究合金成分（Mg,Si,Cu）和热处理（自然时效和预时效）对6xxx系铝合金力学性能的影响。结果表明：合金成分与热处理不仅影响材料的成形性能,而且影响材料的烘烤硬化性能;提高合金中Si含量或Si／Mg比或添加0．3％Cu,可显著提高材料的韧性和成形性能,而预时效将减低材料的韧性和成形性能。对所研究合金的强度、韧性、加工硬化、应变敏感性、成形极限和烘烤硬化性进行了比较和总结。     

Sizing solar-assisted natural rubber dryers

Due to the lack of firewood, the use of solar energy in drying of natural rubber has been envisaged and it has been the subject of several works. The present work is concerned with the design of solar-assisted natural rubber dryers. The system performance is estimated using the average day method. The possibility of heat dumping and the configuration of the collector array are taken into account. To facilitate the user in making a rapid estimation on the collector area required, a simplified sizing method is developed. To this end, an empirical relation is performed by correlating the results of short-cut simulation to design parameters which are easily determined.     

Comparison of the energy yield predictions of stationary and dynamic solar collector models and the models' accuracy in the description of a vacuum tube collector

One stationary and five dynamic models for solar collectors are analyzed in different ways. (1) The models are fitted to a set of measured data and the resulting collector parameters are compared. (2) Step responses of the models are compared in order to illustrate their different reactions to transient conditions. (3) The total daily energy yield predicted by the models for three days of different weather conditions is calculated using a reference collector parameter set. It turns out that the stationary model overpredicts the collector output by up to 15% in the case of one-minute averages of input data, while all dynamic models yield similar results. In the case of hourly input data, the error of the stationary model nearly vanishes.     

关于构建演播室综合监控系统的技术策略

贵阳电视台构建了一套演播室综合监控系统,对演播室直播系统工作中多个层面的运行情况进行实时的检测,并智能预判故障发生的节点,形成由点至面的直观展示及预警方式。结果证明,该系统减少了故障发生几率,提高了故障解决的效率,减轻了人员的安播压力,是直播系统安全管理的有效手段。     

6xxx系铝合金硫酸阳极氧化膜绝缘性研究

采用不同合金,通过控制电流密度以及改进封闭剂等方式,获得绝缘性能优异的阳极氧化膜,并使用金相显微镜、扫描电镜进行微观表征。试验结果表明,在相同铝合金的前提下,氧化电流密度控制在1.5A/dm 2~1.8A/dm^2,膜厚等级AA15,使用ZW1封闭剂可获得绝缘性能优异的阳极氧化膜。     

时效温度和时间对新型Al-6Zn-1.1Mg合金组织性能的影响

采用维氏硬度仪、透射电镜、拉伸试验机和电导率测量仪,研究了时效温度和时间对新型Al-6Zn-1.1Mg合金组织与性能的影响。结果表明:随着时效时间的延长,Al-6Zn-1.1Mg合金基体中先后沉淀析出GP区、η′相(亚稳相MgZn₂)和η相(稳定相MgZn₂)。GP区和η′相均可阻碍位错运动,对合金起到很好的强化作用。当GP区的数量达到最多时,合金的强度和硬度达到第一个峰值。当GP区转变为η′相时,合金的强度和硬度达到第二个峰值。当η′相转变为η相后,合金的强度和硬度开始出现下降。随着时效温度的升高,GP区、η′相和η相的析出逐渐加快,使合金强度和硬度达到两个峰值的时间逐渐缩短,并且两个峰值之间的时间间隔也逐渐缩短。时效温度为120 ℃时,合金强度和硬度的第二峰值高于第一峰值。当时效温度高于120 ℃时,合金强度和硬度的第二峰值低于第一峰值。