寂静地震与地震预测的物理问题

寂静地震是指发生了缓慢的位错、但几乎不辐射地震波的“地震” .在目前的地震预测的物理学研究中 ,通常是通过计算历史上曾经发生过的地震所引起的应力变化 ,或者通过研究地震活动的统计性质或“图像动力学” ,来推测一个断层带上发生地震的危险性 .寂静地震的信息的缺失 ,形成了地震预测的物理学研究中的一个很大的“盲区” ,而在相当程度上 ,解决地震预测的物理问题的主要困难和可能的突破的希望 ,也许就在于此 .寂静地震的研究目前还很不深入 .关于寂静地震的性质 ,文章作者提出两个猜想 :(1)寂静地震的频度 ,满足类似于GR定律的幂律分布 ;(2 )最大的寂静地震的地震矩 ,与“可见”的最大地震的地震矩相当 .     

从临界转变的角度理解地震预测技术

侦测重大地震前相关的地震活动度异常,以此作为地震预测基础理论的研究,在近十年内常被提出讨论.其中有两个典型的算法,包括美国加州Rundle教授的“震模信息学”算法和北京尹祥础教授的“加卸载响应比值”算法.前者旨在揭示地震活动度的高异常变异性;后者则藉助于日、月引力的响应,来研究地壳块体的受损程度.文章从“临界转变理论”出发,认为不管是高异常地震活动度变异,或是象征地壳材料已严重受损的高加卸载响应比值,都是地壳即将出现临界转变(亦即重大地震)的早期征兆.也就是说,原由两个独立研究群体提出的地震活动度算法,实为临界转变的前兆信号的一体两面,可以在临界转变理论下统一起来.     

芦山4.20地震的一段学校疏散录像——初步分析及其对应急避险的统计物理模型的意义

真实灾害情境下的人群撤离录像对约束应急避险的统计物理模型具有不可取代的意义.文章分析了中央电视台《新闻联播》播出的2013年4月20日芦山地震时一段教室疏散的视频,讨论了其对应急避险模型的意义.与2008年汶川地震的情况比较,似可看出受过应急训练的人群与未受过训练的人群在撤离时有不同的表现.     

大地震前出现的异常次声波观测研究

研究了一种在大地震前出现的异常次声波,揭示其与地震发生的空间、时间、强度的对应关系.利用CASI-ICM-2011型次声测量传感器在一系列Ms6.0级以上大地震发生前2周以内检测到的一种频率范围0.001 Hz至0.01 Hz的次声波,其特征有:幅值范围50 Pa至200 Pa,持续时间0.5 h至4 h,传播速度10 m/s至30 m/s,震级越高信号越强.通过建立广域次声传感器网络,成功定位了芦山地震前4天出现的异常次声波,以及巴基斯担地震前12天出现的异常次声波.通过对8年时间连续监测数据的分析,研究了这类次声波的出现规律.同时,对其产生机理提出了大地起伏激发次声波的假设,进行了理论论证,并用智利地震测量信号和玉树地震测量信号证明S波可以激发出本地同振的次声波.文中所列举的数个震前异常次声信号的观测结果对于地震预测的信息获取具有参考价值.     

数值地震预测的关键物理问题*

数值地震预测是地震物理研究中的一个重要课题,具有基础性的科学意义和潜在的应用价值.文章介绍了数值地震预测的三个关键物理问题——地震发生率与应力变化的关系、地震断层的摩擦函数、地球中应力的传递问题,讨论了这些问题的意义、研究现状和发展趋势.     

地震成因及预测预报

本文从地球的结构、地震类型、地震分布规律出发，探讨了地震形成的原因尤其是汶川大地震的成因和对人类带来的灾难，对地震的预测预报工作进行了分析，从六个方面论述了今后国家和各级地震部门及地震工作者在地震预测预报和避震方面要做的工作。     

与地震预测预报有关的几个物理问题

文章简要介绍了与地震预测预报有关的几个物理问题,包括地震活动性问题、地球深部物质的物理性质及其变化问题、地球深部的流体问题、地震破裂问题、地球深部的形变和应力问题.这些问题的研究涉及当代物理学的一前沿领域.唐山大地震后30年来有诸多重要进展.     

以颗粒物理原理认识地震——地震成因、地震前兆和地震预测

本文以地壳和地幔的基本构造和己有观测事实为依据,运用颗粒物理原理,将地壳和地幔作为大尺度离散态颗粒物质体系处理,重新认识地震孕育过程,前兆产生机制及规律,探求地震预测方法和途径.主要结果是:建立了地壳与地幔构成和运动的颗粒模型;提出了引发地震的大地构造力的形成机制,以及地震前兆信息产生和传播规律;说明了地震前兆信息的主要特征及其与地震发生之间的关联,阐述了探测有效地震前兆信息的方法原理;用颗粒流动的阻塞-解阻塞转变原理解释了深源地震发生机制;对以前难以理解的若干地震学现象进行了解释,并讨论了地震的可预测性。由于地壳和地幔的离散结构特征,对于地震孕育的准静力学过程,连续介质理论不再适用.以颗粒物理原理研究地震成因、地震前兆和地震预测,所获得的新认识与传统连续介质地震学观点有本质区别。     

汶川地震后中国及邻区地震活动趋势——地震能量释放特征的“振荡类比”研究

根据欧亚地震带东段地质构造和地震活动特征,选取中国及邻区地震区域,对1897—2008年发生的824次震级Ｍ_s≥60地震的年度释放能量进行滤波和系统分析.结果显示,地震能量释放特征表现为周期性衰减振荡.通过振荡特征分析和计算,从理论上预测中国及邻区长期和中短期强震活动形势.计算结果表明,所选区域内大陆板块地震活跃时间应持续1537 a,如果从1897年开始,即到2050年结束.这一理论结果与中国两千多年历史地震资料分析结论一致,也为我国的地震活跃期持续150 a左右 关键词： 中国大陆及邻区 年度地震能量 强震活动预测 振荡类比     

一种自适应光学闭环系统预测控制算法的仿真研究

介绍了校正大气湍流畸变波前像差的自适应光学系统中,基于预测控制技术对变形镜控制电压进行预测以减少自适应光学系统中时间延迟误差的方法.对受横向风影响的大气湍流畸变波前斜率数据,利用数值仿真方法,研究了基于递推最小二乘(RLS)算法的线性预测控制算法对自适应光学系统变形镜控制电压进行超前预测的方法,并与采用比例积分(PI)...     

Formal structures,the concepts of covariance,invariance, equivalent reference frames,and the principle Relativity

In this paper a given spacetime theoryT is characterized as the theory of a certainspecies of structure in the sense of Bourbaki [1]. It is then possible to clarify in a rigorous way the concepts ofpassive andactive covariance ofT under the action of the manifold mapping groupG _M . For eachT, we define also aninvariance groupG _I T and, in general,G _I T ≠G _M . This group is defined once we realize that, for eachτ ∈ModT, each explicit geometrical object defining the structure can be classified as absolute or dynamical [2]. All spacetime theories possess alsoimplicit geometrical objects that do not appear explicitly in the structure. These implicit objects are not absolute nor dynamical. Among them there are thereference frame fields, i.e., “timelike” vector fieldsX ∈TU, \(U \subseteq M\) M, whereM is a manifold which is part ofST, a substructure for eachτ ∈ModT, called spacetime. We give a physically motivated definition of equivalent reference frames and introduce the concept of theequivalence group of a class of reference frames of kind X according to T, G _X T. We define thatT admits aweak principle of relativity (WPR) only ifG _X T ≠ identity for someX. IfG _X T =G _I T for someX, we say thatT admits a strong principle of relativity (PR). The results of this paper generalize and clarify several results obtained by Anderson [2], Scheibe [3], Hiskes [4], Recami and Rodrigues [5], Friedman [6], Fock [7], and Scanavini [8]. Among the novelties here, there is the realization that the definitions ofG _I T andG _X T can be given only when certain boundary conditions for the equations of motion ofT can be physically realizable in the domainU \(U \subseteq M\) M, where a given reference frame is defined. The existence ofphysically realizable boundary conditions for eachτ ∈ModT (in ?U), in contrast with the mathematically possible boundary condition, is then seen to be essential for the validity of a principle of relativity forT. The methodology of the present paper has been applied to several topics of spacetime physics with very interesting results. Here we mention:

1. The Newtonian concepts of absolute space and absolute time can be presented in a very elegant way as “species of structure”. One of the surprising results is that we succeeded in finding a Lorentzian structure [9] in Newtonian spacetime without introducing any new explict geometrical object in the original structure. The Newtonian spacetime structure and its relation to the relativistic spacetime structure and to the structure of the spacetime of the so-called Lorentz aether theories [11,12] is fully discussed in [13].
2. It is possible to present in a novel and unified way the question concerning experiments designed to detect a possible breakdown of Lorentz invariance, a subject we already dedicated attention to in Rodrigues and Tiomno [11,12] and Rodrigues [14,15]. A full account of this subject will be published elsewhere.
3. In Rodrigues and Scanavini [16], we proved that there are models of General Relativity that contain a canonical privileged locally inertial reference frame that can be physically distinguished from any other frame by experiments doneinside the frame.

Although the formalism of this paper may at first sight look very abstract, actually it is easy to aplly it to specific theories. We present an example at the end of the paper which is sufficiently general to show “in action” almost all concepts introduced in this paper.     

Stability of bipolarons, electron-electron correlations, the variational principle, and the virial theorem

For bipolaron states, a relation is established between the variational principle and the virial theorem optimizing the electronic wave functions. It is shown that a bipolaron one-center state is unstable under any conditions that do not violate basic physical principles. It is established that a stage-by-stage increase in the flexibility of the electronic wave function due to the electron-electron correlations does not stabilize a one-center bipolaron. It is argued that the results of calculations based on the one-center bipolaron model are incorrect.     

Torsion,wormholes, and the problem of the Cosmological constant

We consider the effect of torsion in the early universe to see if it is possible to explain the small value (if not zero) of the Cosmological constant at the present time. For the gauge-theoretic formulation of the Einstein-Cartan theory, we find a wormhole instanton solution which has a minimum (baby universe) radius of the Planck length. The basic difficulty with the wormhole approach is stressed. Finally, we give an explicit calculation from the expression for the evolution of the scale factor, which shows that the spin-dominated interaction term in the very early universe can cancel the Cosmological constant term at that epoch.     

Neutrinos,supernovae, and the origin of the heavy elements

Stars of～8-100 M_⊙end their lives as core-collapse supernovae(SNe). In the process they emit a powerful burst of neutrinos,produce a variety of elements, and leave behind either a neutron star or a black hole. The wide mass range for SN progenitors results in diverse neutrino signals, explosion energies, and nucleosynthesis products. A major mechanism to produce nuclei heavier than iron is rapid neutron capture, or the r process. This process may be connected to SNe in several ways. A brief review is presented on current understanding of neutrino emission, explosion, and nucleosynthesis of SNe.     

Invention,development, and status of the blue light-emitting diode,the enabler of solid-state lighting

The realization of the first high-brightness blue-light-emitting diodes (LEDs) in 1993 sparked a more than twenty-year period of intensive research to improve their efficiency. Solutions to critical challenges related to material quality, light extraction, and internal quantum efficiency have now enabled highly efficient blue LEDs that are used to generate white light in solid-state lighting systems that surpass the efficiency of conventional incandescent lighting by 15–20×. Here we discuss the initial invention of blue LEDs, historical developments that led to their current state-of-the-art performance, and potential future directions for blue LEDs and solid-state lighting.     

Planck, the Quantum, and the Historians

In late 1900, the German theoretical physicist Max Planck derived an expression for the spectrum of black-body radiation. That derivation was the first step in the introduction of quantum concepts into physics. But how did Planck think about his result in the early years of the twentieth century? Did he assume that his derivation was consistent with the continuous energies inherent in Maxwellian electrodynamics and Newtonian mechanics? Or did he see the beginnings, however tentative and uncertain, of the quantum revolution to come? Historians of physics have debated this question for over twenty years. In this article, I review that debate and, at the same time, present Planck's achievement in its historical context.     

ICP-AES同时测定铝合金中Fe,Si,Cu,Mg,Mn,Ni,Zn,Ti,Cr,Sr等杂质元素

本文通过基体干扰和操作条件的试验研究，分别用基体匹配法和干扰系数法校正基体干扰和待测元素间的干扰，建立了以氢氧化钠溶样，ICP－AES同时测定铝合金中铁、锰、铜、锌、镁、钛、硅、镍、铬、锶等杂质元素的方法。方法快速、简便、可靠，回收率93％－102％，适用于进出口铝合金的快速检验。