A Class of Artin-Schreier Towers with Finite Genus

We study the asymptotic behaviour of the genus in some Artin-Schreier towers of function fields over a finite field, and we present a new class of Artin-Schreier towers having finite genus.     

TOWERS OF DERIVATION FOR LIE RINGS AND SOME RESULTS ON COMPLETE LIE RINGS

The well-known tower theorem of groups （resp. Lie algebras） shows that the tower of automorphism groups （resp. derivation algebras） of a finite group （resp. a finite dimensional Lie algebra） with trivial center terminates after finitely many steps. We generalize these results for Lie rings, and present some necessary and sufficient conditions for Lie rings to be complete.     

Mobile phone tower location for survival after natural disasters

This paper discusses the location or strengthening of cell phone towers so as to maximize service coverage and minimize the loss of communications if a natural disaster happens. This paper demonstrates that, under a high likelihood of destruction of antennas (towers), the customary method of maximizing coverage provides poor solutions as compared to the proposed method. In addition to the maximization of service coverage, the objectives of our model include the minimization of expected and worst-case losses. The model is applied to a region in the south of Chile that was stricken by one of the most destructive earthquakes registered in history. Computational results are provided for a variety of scenarios.     

Some lower bounds on Shelah rank in the free group

We give some lower bounds on the Shelah rank of varieties in the free group whose coordinate groups are hyperbolic towers.     

Radial profiles of deposition nozzles for high uniformity

An important design problem is concernedwith uniform wetting of plane areas using arrays of spraying nozzles. Good uniformity requires that the radial profile of deposition from the nozzles, as well as the array spacing, be carefully chosen. The purpose of this paper is to present a technique for computing nozzle profiles which result in high uniformity when used in particular array configurations. The method is based on a spline model for the nozzle, with coefficients determined by minimizing the absolute deviation from mean deposition. Results for square, rectangular, and triangular arrays are presented.     

热带气旋在陆地上重新加强的数值模拟

以2006年1月澳大利亚北部地区热带气旋"NT2006"为例,以宾夕法尼亚州立大学和美国国家气象研究中心联合研制开发的中尺度模式(MM5)为基础,通过轴对称的观点对其登陆后的重新加强进行了数值模拟研究.结果表明,由于"NT2006"的高度不对称性,其"涡热塔"的融合并不呈现明显的轴对称化,因此采用Hendricks的"涡热塔"机制来解释其在陆地上重新加强的机理存在一定困难.通过基于方向平均的绝对角动量面分析,认为Smith的绝对角动量径向辐合机制能较成功地解释"NT2006"在陆地上重新加强和衰减的原因.     

不同气动措施对特大型冷却塔风致响应及稳定性能影响分析

为研究不同气动措施对特大型冷却塔结构风致强度及稳定性能的影响,以内陆某核电特大型冷却塔为例,对无气动措施和增设3种气动措施冷却塔进行刚体测压风洞试验.基于试验结果对比分析了不同气动措施下冷却塔表面平均和脉动风压特性,然后采用有限元方法进行不同气动措施下特大型冷却塔的动力特性、风致响应、局部和整体稳定性能研究,最终提炼出不同气动措施对特大型冷却塔结构抗风性能的影响规律.     

大渡河猴子岩水电站库尾段藏碉群斜坡巨型堆积体的成因分析

丹巴梭坡堆积体是一巨型第四纪堆积体,分布在大渡河的左右两岸,其上有114座珍贵藏碉。对堆积体的成因有冰川成因、冰水成因和泥石流成因等各种观点。在对堆积体现场进行详细勘察的基础上,对藏碉群斜坡巨型堆积体的成因进行了深入分析,得出左岸堆积体的成因主要以崩滑作用为主;右岸堆积体是冰源泥石流和崩塌、滑坡等作用的混杂堆积。并在后来的钻孔揭示中得以验证。这对于川西地区深厚覆盖层成因的揭示以及藏碉群文物的保护均具有重要的意义。     

单线脉动循环式客运索道的运行维护与管理

客运索道的维护和管理是我国特种设备安全管理中的一项非常重要的内容．以丹霞山索道的设备维护和管理为例．分析了单线脉动循环客运索道的设备组成、索道主要设备的维护与维修要点．着重分析了索道用钢丝绳的受力和选型、抱索器的检查和维护以及电气传动装置的维护管理．     

填料层液体分布的理论及数学模型

填料塔设备中流体的流动状况是影响填料塔性能和“放大效应”的主要因素之一。对填料塔液体分布的理论和数学模型进行了总结和评述，为该方面的进一步研究和发展提供参考和帮助。