陨星碰撞对地磁场的影响

在固体地球的假设下,从电子在转动参照系中的Newton运动方程出发,运用经典的电子气模型,指出了地球在自转发生变化时将产生惯性电流,从而影响地球磁矩.由此推论:地磁场有可能因短暂时间内地球自转角动量的变化而受到影响,而小行星、陨星等与地球的天体碰撞,对地磁场有着重大的直接影响,包括地磁场的反向.     

The evidence for the evolution of interplanetary small flux ropes: Boundary layers

We have examined the Wind data in 1996 and identified 21 small interplanetary magnetic flux ropes(SIMFRs),and all the 21 SIMFRs have boundary layer structures.The durations of the boundary layers varied from several minutes to 30 minutes.These boundary layers also have properties of high proton temperature,density,and plasma beta.These boundary layers are formed by magnetic reconnections.In addition,in three events magnetic reconnections were occurring inside the boundary layers.It indicates that the flux rope structures have propagated for some period of time,and their boundaries were still evolving through interaction with the background solar wind.Namely it is very possible that the SIMFRs came from the solar corona.     

碰撞逃逸船舶的认定

从海上碰撞事故调查的角度,分析和阐述了在认定碰撞肇事逃逸船时应考虑的因素。这些因素包括碰撞事故发生后的报告,通报,肇事嫌疑船的特征,碰撞事故的时间,地点,肇事嫌疑船的触损部位和油漆样本,肇事嫌疑船在碰撞前后的航向及航速等的推算,港口船舶通航记录以及相关海区雷达站的记录等。     

Retrograde spins of near-Earth asteroids from the Yarkovsky effect

Dynamical resonances in the asteroid belt are the gateway for the production of near-Earth asteroids (NEAs). To generate the observed number of NEAs, however, requires the injection of many asteroids into those resonant regions. Collisional processes have long been claimed as a possible source, but difficulties with that idea have led to the suggestion that orbital drift arising from the Yarkovsky effect dominates the injection process. (The Yarkovsky effect is a force arising from differential heating-the 'afternoon' side of an asteroid is warmer than the 'morning' side.) The two models predict different rotational properties of NEAs: the usual collisional theories are consistent with a nearly isotropic distribution of rotation vectors, whereas the 'Yarkovsky model' predicts an excess of retrograde rotations. Here we report that the spin vectors of NEAs show a strong and statistically significant excess of retrograde rotations, quantitatively consistent with the theoretical expectations of the Yarkovsky model.     

液滴与球形颗粒相互碰撞的数值模拟

为了研究液滴与球形颗粒的碰撞规律,建立了正确反映液滴与颗粒间相互碰撞的物理模型.利用所建模型模拟了液滴与颗粒的动态碰撞过程,进而对液滴半径铺展系数及液膜中心高度系数进行分析,研究了液滴与颗粒间的撞击速度、湿润角、粒径比等参数对碰撞结果的影响.结果表明:在一定条件下,撞击速度的提高会增大液滴的最大铺展半径系数,当撞击速度...     

Occultation of X-rays from Scorpius X-1 by small trans-neptunian objects

Since the discovery of the trans-neptunian objects (TNOs) in 1992, nearly one thousand new members have been added to our Solar System, several of which are as big as--or even larger than--Pluto. The properties of the population of TNOs, such as the size distribution and the total number, are valuable information for understanding the formation of the Solar System, but direct observation is only possible for larger objects with diameters above several tens of kilometres. Smaller objects, which are expected to be more abundant, might be found when they occult background stars, but hitherto there have been no definite detections. Here we report the discovery of such occultation events at millisecond timescales in the X-ray light curve of Scorpius X-1. The estimated sizes of these occulting TNOs are < or =100 m. Their abundance is in line with an extrapolation of the distribution of sizes of larger TNOs.     

蒸汽小流量下减温减压器的实验研究

介绍了减温减压器的工作原理,以及在蒸汽小流量工况下进行的减温过程和减压过程的实验研究。实验结果表明,在蒸汽小流量下减温减压器对蒸汽的减温减压作用明显,工作性能稳定,能够获得需要的出口蒸汽参数,可以为今后的蒸汽排放系统的设计和优化工作提供参考资料。     

Pressure gradient evolution in the near-Earth magnetotail at the arrival of BBFs

Using in situ observations from THEMIS A, D and E during the 2008-2011 tail season, we present a statistical study of the evolution of pressure gradients in the near-Earth tail during bursty bulk flow （BBF） convection. We identified 138 substorm BBFs and 2,197 non-substorm BBFs for this study. We found that both the pressure and the Bz component of the magnetic field were enhanced at the arrival of BBFs at the spacecraft locations. We suggest that the increase of Bz during non-substorm BBFs is associated with flux pile-up. However, the much stronger enhancement of Bz during substorm BBFs implies the occurrence of magnetic field dipolarization which is caused by both the flux pile-up process and near-Earth current disruption. Furthermore, a bow-wave-like high pressure appears to be formed at the arrival of substorm BBFs, which is responsible for the formation of region-1-sense FACs. The azimuthal pressure gradient associated with the arrival of substorm BBFs lasts for about 5 min. The enhanced pressure gradient associated with the bow wave is caused by the braking and diversion of the Earthward flow in the inner plasma sheet. The results from this statistical study suggest that the braking and azimuthal diversion of BBFs may commonly create azimuthal pressure gradients, which are related to the forrnation of the FAC of the substorm current wedge.     

利用弹簧模型提取物体轮廓

复杂背景下的物体轮廓提取是一个实际的图象处理系统必须面对的问题,而传统的轮廓提取方法在此情况下往往因为大量的噪声而失效,本文所处理的胃部的SDC图象中物体的边缘就处在与边缘的斜率和灰度梯度极为相近的噪声中,所以较难提取,我们利用UBF图象已提取的轮廓建立弹簧模型,根据两种图象中胃部的形变关系,较好的提取了SDC图象中的胃部轮廓,该方法对其它复杂前景下的图象处理有较好的参考价值。     

定子磁链暂态对双馈感应电机接入系统小干扰稳定的影响

该文研究了定子磁链暂态过程对双馈感应电机接入系统的小干扰稳定的影响情况。首先建立了描述双馈感应电机电磁过程的8阶详细模型,并进一步推导了它的小干扰稳定的计算公式。根据Lyapunov特征值理论,对单个双馈感应电机经过传输线接入无穷大母线系统进行了数值分析。结果表明:无论是控制器参数变化还是传输线路电抗变化,6阶模型的稳定边界范围都比8阶模型更大。采用简化6阶模型不利于系统稳定性分析。     

土压力计算存在的问题

针对工程中土压力计算的方法及目前的研究现状,讨论了经典的Ｒａｎｋｉｎｅ和Ｃｏｕｌｏｍｂ理论的局限性,推导出任意位移和土压力的关系,最后关于土压力计算提出了几点建议。     

模糊 Quantale 范畴中的投射对象

引入了模糊弱-稳定完全分配格的概念,证明了模糊序半群的下集格带有合适的运算是模糊弱-稳定完全分配格,给出了模糊 Quantale 是模糊弱-稳定完全分配格的充要条件;讨论了模糊 Quantale 中的投射对象,证明了模糊 Quantale 中的 E-投射对象恰是模糊弱-稳定完全分配格。     

血地上的颤栗——长篇历史小说《大清血地》解读

历史如何与艺术有机的结合起来,是否既具有自觉的历史意识,又具有鲜明的现代意识和丰厚的审美意识,《大清血地》从正面给我们阐释了历史小说作为跨越在艺术和历史学这两个门类之间的一种艺术形式的真谛.     

CALPHAD技术在稀土氯化物-碱土金属氯化物二元系相图中的应用

随着科学技术的不断发展,CALPHAD技术已经成为相图研究的一个非常重要的方法和手段．根据稀土氯化物一碱土金属氯化物二元系相图的实验数据,利用CALPHAD技术可以获得一系列热力学参数,这些热力学参数为稀土金属的冶炼工业生产提供了非常重要的指导．     

基于轨迹不确定的移动对象的预测处理

针对带有不确定性移动对象的预测查询处理可利用不确定轨迹模型来实现的问题,本文首先结合了移动对象具有自身运动的确定性及外界影响的不确定性建立了一个新的不确定轨迹模型;其次,设计了一种新的可用于对不确定性移动对象预测查询处理的索引结构B-TPR树,这种结构利用了本文模型中提到的不确定性移动对象的轨迹在未来一段时间内分布于某个角度范围的思想,对移动对象进行规则划分,从而达到更好的索引不确定性移动对象,实现预测查询处理.     

加筋土技术的推广和应用

阐述了加筋土技术的基本原理、结构设计、材料选定和优点,指出该项技术应尽快在山西省得到推广和应用。     

Virtual Earth在物流系统中的应用

随着近年来数字化地球的发展,以及车载gps近来的迅猛发展,使得电子地图逐步渗入到物流系统中。微软提供的联机地图服务Virtual Earth,使得开发人员在物流管理系统中应用电子地图更容易集成使用。系统操作员就可以直观的、及时的调整最佳路线,选择合适的运输车辆,大量节约运输成本。客户通过相关凭证获取货物信息后可以更直观的了解货物在途信息,极大地提高客户的工作效率。     

地表形态的趋势描述法

本文利用数理统计方法建立地表曲面的经验方程,并由此给出了地形等高线的一种新的绘制方法.