Head-on collision of magnetoacoustic solitary waves in magnetized quantum electron-positron-ion plasma

This article presents the first study of the head-on collision between two magnetoacoustic solitary waves (MASWs) in magnetized quantum plasma consisting of electrons, positrons, and ions, using the extended Poincaré-Lighthill-Kou (PLK) method. The effects of the magnetic field intensity, the positron to ion number density ratio, the quantum parameter, the Fermi temperature ratio, and plasma number density on the solitary wave collisions are investigated. It is shown that these factors significantly modify the phase shift.     

中太平洋海山区尖顶和平顶海山结壳成矿与分布的比对研究

尖顶海山和平顶海山是洋底海山的两种类型,同时也是富钴结壳资源赖以成长的主要载体,两者在地形上具有显著差别,资源状况和分布也不尽一致。以地形分类为基础,就中太平洋海山区两类海山结壳的成矿特征、宏微观构造、矿物和化学组成以及空间分布等进行了比对研究。研究认为,尖顶海山体积虽小,但地形演化连续,底层流及环境氧化性较强,有利于结壳的长期稳定生长,结壳厚度总体较大,富成矿元素和生物组分,远景成矿区域连续绵长。平顶海山山体巨大,顶部和斜坡陡崖区不利于结壳成长,底流活动只在山顶边缘和山脊地带表现突出,环境氧化性整体较弱,后期构造活动相对频繁,结壳总体厚度较小,铁,碎屑和热液组分含量较高,远景矿区相对狭窄。     

兰州至关中电线积冰与导线线径及高度关系

对2006—2007年、2007—2008年冬季甘肃、陕西、宁夏多个测点不同线径、不同架线高度电线积冰观测资料分析可知,不同线径电线积冰的净直径、净厚度、等效厚度、积冰重量间存在显著线性关系。直径为26 mm导线电线积冰重量约为18 mm导线的1.2倍,是4 mm铁丝的1.3倍。直径为26 mm导线与直径为18 mm导线电线积冰间的各项关系都较26 mm导线与4 mm铁丝的线性关系更为显著;大直径导线电线积冰的净直径、净厚度、等效厚度均小于4 mm铁丝;26 mm导线与18 mm导线电线积冰的净直径、等效厚度基本相等。电线积冰等效厚度是架设高度比的幂函数;忽略水滴下沉速度,在假定捕获系数为常数、假定时间各物理量均衡不变情况下,电线积冰重量与电线导线线径成正比,且随架设高度的增加而增加。     

Fluorine in drinking water and urine in the urban and rural areas of northwestern China——Its determination by a fluoride ion selective electrode

In this study, the author determined fluorine in drinking water and urine of residents who are divided into four age groups (5, 12, 35-44, 65-74 aged), living in Huangling City, Shaanxi Province and at 6 villages of Qin'an County, Gansu Province, P.R.China. Some residents are living in fluorine exposure areas. A total of 929 residents (463 females and 466 males) involved in the study were selected from 7 tap water systems. Drinking water samples were collected from each area and analyzed using the fluoride ...     

Spectral aspects of the Gaussian beam method: reflection from a homogeneous half-space

Summary. Use of paraxially approximated Gaussian beams continues to be actively pursued for construction of synthetic seismograms in complicated environments. How to select the beams in the stack remains a source of difficulty which has primarily been addressed by semi-heuristic considerations. In this paper, the classical example of line-source field reflection from a homogeneous half-space that can sustain a head wave is examined from a plane-wave spectral point of view. The individual beam fields are modelled exactly by the complex source point technique, which emphasizes the complex spectral content of these wave objects. The quality of the paraxial approximation of a typical reflected (Gaussian) beam characterized by different parameters is examined from this perspective, and is compared with uniform and non-uniform asymptotics generated from the exact beam field spectral integral. With this information as background, the reflected field for a real line-source is synthesized by beam superposition. Except for the immediate vicinity of the critical reflection angle, the well-known failure of narrow paraxial beams, no matter how densely stacked, to reproduce the head wave effects is shown to be due to the inadequate spectral content of these beams and not to the failure of beam stacking per se. When the rigorous solutions are used for the narrow-waist beams, even relatively few suffice to yield agreement with the exact solution. This circumstance emphasizes the importance of fully understanding the spectral implications of various beam stacking schemes.     

湘湖的形成演变及其发展前景

湘湖的形成、演变和发展在宁绍平原湖泊变迁中为特例.湘湖的存亡和当地的自然、人文条件密切相关,在历史时期作为农业灌溉的湘湖,由于职能转变,目前残剩为河流型的湖泊,但湖内粘土宜制砖瓦的功能,致使水域扩大.湘湖可能发展为风景区.     

震灾保险新制式的理论依据及其科学内涵

震灾保险新制式是建立在新观念，新思维，新概仿之上的一种独特的保险机制，本文通过对其理论基础以及科学－社会意义的阐述，进一步揭示了这一新型制式的实质和内涵。     

浅谈UPS电源蓄电池的使用和维护

随着计算机的日益普及，UPS不间断电源得到广泛的应用。广东省气象部门随着卫星通信系统建设于1997年起地区局安装了3kw美国产的IPM UPS,1998年底随x..25的开通各县又配置了国产小型“华达”UPS。这就自然引出了蓄电池的使用和维护问题。由于蓄电池是UPS电源能不间断供电的能量支持，如何发挥它的性能，延长其寿命，直接关系到UPS电源能否供给关键负载合格的电源，以及UPS本身的安全运行。……     

层状介质中断层位错引起的重力异常及其数值模拟

修正了文献［１］给出的两个公式和计算机程序中的个别错误，并根据文献［１］利用层状介质中的位错理论及其与相应重力变化的关系［２，５］，通过数值模拟方法研究了矩形位错面在不同尺度、倾向、埋深和位错的情况下有不同取向、量值的重力异常变化。此外，还对唐山地震、共和地震的重力资料作了几个测点的计算以探索地震物理前兆场空间和强度分布的复杂性。结果表明，断层错动引起的重力变化在空间、强度上的分布是十分复杂的。它是位错地表形变和地下层界面形变效应共同作用的产物，既可以是正异常，也可以是负异常。位错源的几何条件、埋深条件、位错方向和量值等对重力的空间、强度分布和范围有较强的影响。这就说明对于地震与重力异常的关系不能一概而论，要考虑一次地震特定条件的影响。本研究也为我们理解其它地震前兆物理场的复杂性提供了有益的启示     

GT－1型工程导向孔多功能无线探测仪和GD－200型钻机在非开挖铺线技术中的应用

介绍ＧＴ－１型工程导向孔多功能无线探测仪的功能、组成参数和ＧＤ－２００型全液压动力头式钻机的组成、性能、主要参数、主要特点以及两者在非开挖铺设管线技术中的配套试验情况。