Collision effects on propagation characteristics of electromagnetic waves in a sub-wavelength plasma slab of partially ionized dense plasmas

Intensive collisions between electrons and neutral particles in partially ionized plasmas generated in atmospheric/sub-atmospheric pressure environments can sufficiently affect the propagation characteristics of electromagnetic waves,particularly in the sub-wavelength regime.To investigate the collisional effect in such plasmas,we introduce a simplified plasma slab model with a thickness on the order of the wavelength of the incident electromagnetic wave.The scattering matrix method (SMM) is applied to solve the wave equation in the plasma slab with significant nonuniformity.Results show that the collisions between the electrons and the neutral particles,as well as the incident angle and the plasma thickness,can disturb the transmission and reduce reflection significantly.     

基于ANSYS/LS-DYNA的薄板结构撞击响应分析

薄板结构在建筑工程领域有广泛的应用,受到外物的撞击是其损伤的主要原因之一,薄板结构在撞击作用下发生塑性变形、侵彻和穿透等破坏,因而研究薄板结构在撞击作用下的响应具有重要的工程应用价值。采用有限元软件ANSYS/LSDYNA对钢球低速撞击薄铝板这一过程进行模拟,通过铝板应力云图和竖向位移时程曲线评估了铝板塑性变形的范围、程度,研究了在单物撞击下铝板产生塑性变形范围、程度与钢球质量之间的关系,同时也为研究新型薄板材料抗撞击性能、塑性变形评估提供了更加经济、有效的方法。     

天然护色剂对酱牛肉护色效果的研究

针对于用红曲红色素作为表面着色剂的小包装方便酱卤肉制品在贮藏期间易发生氧化褪色这一现象,通过测定贮藏过程中酱牛肉的pH、红度值、色素残留率、感官评价,研究抗坏血酸钠、葡萄糖、茶多酚及其复合剂作为抗氧化剂对产品表面红曲红色素的保护效果。研究表明:0.05%的茶多酚护色效果最为显著,0.06%的抗坏血酸钠和0.01%的葡萄糖也明显起到了护色的效用,复合剂的相乘效用使其比单一组抗氧化效果更明显,且与市售护色剂间存在明显差异性(P<0.05)。复配护色剂(0.06%抗坏血酸钠+0.01%葡萄糖+0.05%茶多酚)能使酱牛肉储存28d后,红度值仍能达到12.51、色素残留率达到46.54%、感官评价达到3.5分,与对照组差异显著(P<0.05)。     

新型管道重防腐环氧粉末涂料的研制与应用

研制的重防腐环氧粉末涂料适用于钢质管道单层结构熔结环氧粉末外涂层,经过涂覆的钢管可用于工作温度为-30~100℃的埋地或水下管道设施,具有良好的防腐蚀性能,达到SY/T 0315标准要求。     

20号钢管状电感探针在模拟某气田环境下的腐蚀失效分析

模拟某气田CO2腐蚀环境，利用SEM，EDAX和XRD分析方法，对20号钢管状电感探针的腐蚀机理和失效过程进行了分析研究。结果表明：腐蚀产物分为两层，外层主要由FeCO3晶体和FeS组成，膜层较厚，强度较低且质地疏松多孔；内层主要为FeO和少量FeCl，组成，较外层稍致密，与金属基体间的附着力较差，产物膜易脱落。腐蚀产物膜的多孔特性诱发了局部腐蚀，溶液中Ca^2＋和Cl^-的存在对样品的局部腐蚀起到了促进作用。探针的失效最先从测量试片封堵端开始，焊接工艺遗留残余应力使得此处腐蚀较快，容易发生腐蚀开裂，腐蚀介质从开裂处渗入试片空腔内，加速了探针的失效。     

Studies on omnidirectional enhancement of giga-hertz radiation by sub-wavelength plasma modulation

The technology of radio frequency (RF) radiation intensification for radio compact antennas based on modulation and enhancement effects of sub-wavelength plasma structures represents an innovative developing strategy.It exhibits important scientific significance and promising potential of broad applications in various areas of national strategic demands,such as electrical information network and microwave communication,detection and control technology.In this paper,laboratory experiments and corresponding analyses have been carded out to investigate the modulation and enhancement technology of sub-wavelength plasma structure on the RF electromagnetic radiation.An application focused sub-wavelength plasma-added intensification up to ～7 dB higher than the free-space radiation is observed experimentally in giga-hertz (GHz) RF band.The effective radiation enhancement bandwidth covers from 0.85 to 1.17 GHz,while the enhanced electromagnetic signals transmitted by sub-wavelength plasma structures maintain good communication quality.Particularly,differing from the traditional RF electromagnetic radiation enhancement method characterized by focusing the radiation field of antenna in a specific direction,the sub-wavelength plasma-added intensification of the antenna radiation presents an omnidirectional enhancement,which is reported experimentally for the first time.Corresponding performance characteristics and enhancement mechanism analyses are also conducted in this paper.The results have demonstrated the feasibility and promising potential of sub-wavelength plasma modulation in application focused RF communication,and provided the scientific basis for further research and development of sub-wavelength plasma enhanced compact antennas with wide-range requests and good quality for communication.     

BP神经元网络在炼油厂低温腐蚀预测模型上的应用

将神经元网络建模应用于炼油厂腐蚀速率预测,整理分析现场数据,对神经元网络模型进行训练,建立了低温腐蚀速率预测模型。采用改进的Levenberg-Marquardt算法训练模型,较传统的梯度下降法可以更好地完成算法收敛。神经元网络建模后,可以将现有的腐蚀数据涵盖在腐蚀模型中,便于腐蚀数据的管理和查询,同时对现场参数变化影响腐蚀速率的情况起到了预测作用。预测结果与实际值之间的平均方差为0.013 2,可以满足现场需要。     

坡面张裂缝充水对平面滑动边坡稳定性影响研究

为了研究平面滑动边坡中张裂缝位于坡面上时边坡稳定性变化情况,根据极限平衡理论,建立坡面张裂缝参数关系式,通过改进水压分布函数获得各水压分布形式下张裂缝和滑动面的水压力表达式,运用Matlab编制程序,探讨不同水压分布形式下各参数对边坡安全系数的影响,以及不同水深条件下,各水压分布形式边坡滑动面临界倾角变化情况。研究表明,地下水位的升高使各水压分布形式下边坡安全系数变小,其中张裂缝与滑动面的连接点透水、滑动面在边坡出露位置不透水且滑动面和张裂缝中均有水压的水压分布形式变化幅度最大,地下水位的升高使该形式的临界倾角变大,使其他形式的临界倾角变小。