Ion migration in nepheline: a dielectric spectroscopy and computer modelling study

 Using a combination of dielectric spectroscopy and atomistic computer simulation techniques, the dynamical behaviour of the loosely bound (Na⁺ and K⁺) channel ions in nepheline has been investigated. The low-frequency dielectric properties of a natural Bancroft nepheline have been studied from room temperature to 1100 K. At each temperature, the dielectric constant, conductivity and dielectric loss were determined over a range of frequencies from 100 Hz to 10 MHz. At high temperatures a distinct Debye-type relaxation in the dielectric loss spectrum was observed; the activation energy for this process was determined to be 1.38 ± 0.02 eV. Atomistic simulation techniques were used to elucidate the mechanism and energetics of cation migration. A mechanism involving the hopping of Na⁺ ions between oval sites and partially occupied hexagonal (K⁺) sites, via a bottleneck consisting of a distorted sixfold ring of (Al,Si)O₄ tetrahedra, was found to give a calculated energy barrier in very good agreement with the experimentally determined activation energy. These results confirm the nature of the process responsible for the observed dielectric behaviour. Overall, this study demonstrates the intrinsic, microscopic control of cation diffusion processes in rock-forming minerals. Identifying specific energy barriers and preferred diffusion pathways is fundamental to the prediction of diffusion energetics. Received: 8 May 2000 / Accepted: 21 July 2000     

微机BIOS的保护

介绍了一种纯硬件方式的微机 BIOS程序保护方法 ,从根本上解决了病毒对 BIOS的侵害 ,具有一定实用价值     

地球物理勘探技术的进展

近年来，地球物理技术发展非常快，其重点可从下列几个方面进行综述：１）电子和计算机技术的迅猛发展是推动物探技术发展的源泉。２）地震装备和采集技术的时展是基于三维和高分辨率勘探的需求。３）地震资料处理从传统批处理向勘探、开发交互处理方向演变。４）面临当今信息爆炸的情况下，地震解释将综合更多的信息以降低石油勘探开发的风险。５）开采地球物理和地震反演近年来有长足的进展。６）其他学科的一些新理论和新算法已在     

岩体裂隙网络分数维计算机模拟

岩体裂隙网络的研究是一个方兴未艾的课题,而用分形几何来研究岩体裂隙网络是一种行之有效的手段,本文将介绍由笔者编制的计算机裂隙网络分数维求解方法及程序,以达到快速、便捷而又准确地求解复杂网络的分维数。     

中国大陆强震轮回活动的计算机模型研究

通过对中国大陆7级以上强震的研究发现,地震活动呈现为时间上轮回和空间上迁移的动态图像。为探索这种图像的物理本质,本文应用非线性动力学模型来模拟在统一构造应力场作用下含有多个活动地震带的地震构造块体的地震活动。文中用若干列并联排列的基本元件(由Maxwell体和刚性滑块组成)来模拟地震活动带,并用耦合元件来模拟地震活动带之间和带内各段之间的相互耦合作用。本文的研究结果有助于理解强震的轮回活动以及高潮中成组强震间的相互影响特征。     

地震预报实用化系统概况

近年来,国家地震局分析中心先后完成了一系列有地震预报的计算机处理系统。为了使这些计算机系统充分发挥作用。为了把这些分散的系统连接在一起,发挥整体效益,我们已把有关的系统连接在一起,构成统一的整体,称作地震预报实用化系统。本文介绍此系统的主要构成及主要功能,数据流程及全国数据库等情况。     

地震孕育发生的场源关系初步研究

场和源在地震学和地震预报研究中已成为两个最重要分友。本文应用计算机模型研究地震活动中的场源关系。模型以非线性元件构成的网络系统来模拟含有多个地震活动带的地震构造块体的地震活动。在模型边界上加以定常应变速率，则在模型中可产生高低起伏的轮回式地震活动，并形成应力场强度和应变能高低起伏的准周期变化，各地地震活动轮回有其主体活动地区，不同的轮回之间常显示出地震主体活动区的空间转移。同时，若将模型中达到一定     

Computer simulation of nearshore bar formation

A computer simulation model, developed from a conceptual model of sediment transport patterns associated with nearshore bars, is presented. The model simulates wave shoaling, breaking and reformation along a profile normal to the shore from deep water to the beach and determines rates and directions of sediment transport under wave orbital currents and rip cell circulation. The model successfully generates a barred profile from an initial planar profile and under most conditions achieves a state of dynamic equilibrium with sediment circulating across the bars. Input values for wave height, wave period, offshore slope and tidal range were varied in turn in order to determine their individual effect on the shape of the equilibrium profile formed. Breaker type—spilling or plunging—is incorporated in the model and also appears to be a significant factor in determining the shape of the equilibrium profile.     

Alkali ion migration in albite and K-feldspar

As part of a study of ion migration mechanisms in feldspars, the dynamical behaviour of the alkali metal cations ions in albite and K-feldspar has been investigated using a combination of dielectric spectroscopy and atomistic computer simulation techniques. The low-frequency dielectric properties of these minerals have been studied from room temperature to 1100 K. At each temperature, the dielectric constant, conductivity and dielectric loss were determined over a range of frequencies from 100 Hz to 10 MHz. At high temperatures a distinct Debye-type relaxation in the dielectric loss spectra was observed for both albite and K-feldspar; the activation energy for these processes was determined to be 1.33 eV in both albite and K–feldspar. Atomistic simulation techniques were used to elucidate the mechanism and energetics of the cation migration processes. Mechanisms involving the conventional hopping of Na⁺ and K⁺ ions between cation sites in the (010) plane were found to give calculated energy barriers in good agreement with the experimentally determined activation energies. These results assist in understanding the nature of the processes responsible for the observed dielectric behaviour.     

CTM-DI磁力仪在磁房改造中的应用及观测中的几个问题

本文介绍了CTM-DZ磁力仪的性能及应用，并根据实践经验提出了在使用该仪器过程中应注意的几个问题。