Dark matter and rotation curves of stars in galaxies

The dark matter accretion theory (around a central body) of the author on the basis of his 5‐dimensional Projective Unified Field Theory (PUFT) is applied to the orbital motion of stars around the center of the Galaxy. The departure of the motion from Newtonian mechanics leads to approximately flat rotation curves being in rough accordance with the empirical facts. The spirality of the motion is investigated.     

Performance of multiple tuned mass dampers for attenuating undesirable oscillations of structures under the ground acceleration

Multiple tuned mass dampers (MTMDs) consisting of many tuned mass dampers (TMDs) with a uniform distribution of natural frequencies are considered for attenuating undesirable vibration of a structure. The MTMD is manufactured by keeping the stiffness and damping constant and varying the mass. The structure is represented by its mode‐generalized system in the specific vibration mode being controlled using the mode reduced‐order method. The optimum parameters of the MTMD are investigated to delineate the influence of the important parameters on the effectiveness and robustness of the MTMD by conducting a numerical searching technique in two directions. The parameters include: the frequency spacing, average damping ratio, mass ratio and total number. The criterion selected for the optimization is the minimization of the maximum value of the dynamic magnification factor (DMF) of the structure with MTMD (i.e. Min.Max.DMF). In this paper, for the sake of comparison, the MTMD(II), which is made by keeping the mass constant and varying the stiffness and damping coefficient, and a single TMD are also taken into account. It is demonstrated that the optimum frequency spacing of the MTMD is the same as that of the MTMD(II) and the optimum average damping ratio of the MTMD is a little larger than that of the MTMD(II). It is also found that the optimum MTMD is more effective than the optimum MTMD(II) and the optimum single TMD with equal mass. Copyright © 2000 John Wiley & Sons, Ltd.     

Application Study on Correction Method for Lag of Water Level Response to Earth Tide and Atmospheric Pressure

INTRODUCTIONBased onthe results gathered after manyyears of seismic groundwater observation,itisfoundthatthe water level in deep wells responds to the earth’s tide and atmospheric pressure and changesaccordingly,not onlyin amplitude ,but also in the phase lag by different degrees .Some phase lagslast onlyfor several minutes ,while some last aslong as more than one hour (Zhang Zhaodong,1988 ;Wang Chengmin,1990) .The result of this theoretical research shows that the phase lag response to…     

钻探参数实时采集系统研制与应用

钻探参数实时采集系统研制的目的是向钻探技术及管理人员提供直观的钻探实时参数,通过该系统可全天候的掌握钻探工况。钻探参数采集的方法是通过传感器采集压力、转速、位移、流量、液位等物理参数,使用配套的软硬件设备进行数据转换和处理,在人机交互界面显示直观的工程参数。该系统根据野外现场不同工作环境可以使用互联网、GPRS终端或者北斗卫星终端把现场实时工程数据无线传输至远程服务器上,用户通过手机或电脑即可查看到现场的实时或历史工程数据。采用本系统可以预防和减少钻探事故,为事故处理提供数据支撑,为实现钻探自动化、智能化提供基础数据。     

橡胶砂弹性动力学参数的弯曲-伸缩元试验研究

橡胶砂作为一种廉价环保的土工材料,应用前景十分广阔,关于其力学特性的研究具有重要意义。采用弯曲–伸缩元法对橡胶砂进行了剪切波和压缩波联合测试,分别采用离散频率扫描法和初达波法确定了剪切波和压缩波的传播时间,进而得到其弹性动力学参数：初始剪切模量、侧限模量和泊松比,分析了橡胶含量和围压对橡胶砂弹性动力学参数的影响。结果表明：在同样围压下,随着橡胶含量的增加,橡胶砂初始剪切模量和侧限模量逐渐减小,初始泊松比逐渐增大;在同样橡胶含量下,随着围压的增大,橡胶砂初始剪切模量和侧限模量逐渐增大,初始泊松比逐渐减小。最后,在此基础上进行了两种因素耦合效应的分析以及相关力学机制的探讨。     

非连续变形分析中块体大转动问题研究

原有非连续变形分析（DDA）采用一阶近似后的位移增量表达式更新块体构形,推导相关子矩阵,且对不同时步计算出的应变增量直接叠加,当模拟的块体发生大转动时往往会产生较大误差。为考虑块体转动与变形的耦合作用,引入先变形、后转动的块体位移增量表达式。重新推导了惯性力子矩阵,将块体转动时的离心力与科氏力加到荷载矩阵中。计算时对应变分量及其相关变量进行坐标变换与修正,并采用新引入的位移增量表达式计算块体顶点位移,进行后接触修正与更新块体构形。数值算例表明,改进后的程序能够消除转动带来的误差,自动考虑了块体转动时离心力和科氏力引起的变形,应变计算精度更高。改进方法克服了块体体积自由膨胀、应变场畸变等问题,给出了合理的块体应变。     

筋土界面特性宏细观分析试验仪器研制与应用

为了更全面地分析筋土界面相互作用特性,改制了一台可视加筋土界面特性宏细观分析的试验仪器,可开展不同土工合成材料与填料的直剪和拉拔试验;该仪器改进了试验箱的尺寸,可方便两种试验的对比分析,增加了图像摄录系统,可进行试验过程的细观分析。使用新研制仪器分别进行了土工合成材料（土工格栅和土工布）加筋尾矿砂的直剪和拉拔试验,试验结果表明:两种试验条件下,土工格栅与尾矿的界面参数（似黏聚力和似摩擦角）及似摩擦系数均比土工布与尾矿的界面参数和似摩擦系数大;直剪试验下筋材网孔的有无对筋-尾矿界面参数均有较大影响,拉拔试验下筋材网孔有无对筋-尾矿界面参数似黏聚力的影响较为显著,对似摩擦角的影响较小。随着宏观变量法向应力的增加,细观参数孔隙率减小,平均接触数增加,反映在宏观上的现象就是填料颗粒被压密,筋材需要克服的阻力增大。该试验仪器能够较好地分析筋土界面宏细观特性,获得关键技术指标以用于加筋结构的设计。      

西南某岩溶区地下水系统示踪试验与解析

以西南某典型岩溶区为例,解析示踪试验在岩溶管道连通性以及获取水文地质参数中的应用。选择落水洞为投放点,分别从落水洞西侧和东侧寻找地下水出露点作为接收点,判别落水洞地下径流的实际去向以及落水洞与接收点之间的水力联系。结合Qtracer2软件对示踪试验成果进行定量解析,确定示踪剂回收率、地下水平均流速、最快流速,估算出岩溶管道结构特征和水文地质参数。结果表明:落水洞与接收点JS01、JS03之间不存在直接水力联系;落水洞与接收点JS02存在水力联系且岩溶管道极为发育,含水介质不均匀,地下水运移路径较为通畅,为典型的紊流流态;落水洞地下径流的主要方向是由西向东,但在丰水期雨量较大期间,接收点JS04能够接收到荧光素钠,说明丰水期水位上涨后两者间会有水力联系,导致部分水量向落水洞西侧排泄。     

Volatile element chemistry during accretion of the earth

We review some issues relevant to volatile element chemistry during accretion of the Earth with an emphasis on historical development of ideas during the past century and on issues we think are important. These ideas and issues include the following: (1) whether or not the Earth accreted hot and the geochemical evidence for high temperatures during its formation, (2) some chemical consequences of the Earth’s formation before dissipation of solar nebular gas, (3) the building blocks of the Earth, (4) the composition of the Earth and its lithophile volatility trend, (5) chemistry of silicate vapor and steam atmospheres during Earth’s formation, (6) vapor - melt partitioning and possible loss of volatile elements, (7) insights from hot rocky extrasolar planets. We include tabulated chemical kinetic data for high-temperature elementary reactions in silicate vapor and steam atmospheres. We finish with a summary of the known and unknown issues along with suggestions for future work.     

含水率对页岩动态弹性力学性质的影响研究

声波测试是研究岩石动态力学性质的一种重要的无损检测方法。在有机质丰富的页岩中,页岩的力学性质受含水量、岩石层理、总有机碳含量(TOC)和微观结构变化的影响。本研究在声波测试前,首先使用CT扫描技术对鹰滩页岩的每组测试样品进行扫描,对实验样品的完整性进行筛选,利用核磁共振法(NMR)测定样品的含水率。然后利用超声波脉冲传输技术在不同围压下对每组测试岩心进行声波测试。测试后,利用X射线衍射(XRD)分析了样品的矿物组分,利用扫描电子显微镜(SEM)对微结构进行了表征。研究结果表明:围压和含水率对纵波(P波)和横波(S波)速度均有显著影响,两种速度都随着围压的增加而增加。含水率的增加会降低横波与纵波的波速,含水率对横波速度比纵波速度的影响更大。含水率降低了杨氏模量和剪切模量,增加了体积模量、拉梅参数和泊松比。分析表明,引起岩石力学性质含水率变化的机制可能是粘土-水相互作用、化学反应和毛细压力变化的综合结果。