原地地应力状态和岩石强度对流体诱发地震活动影响的实验室研究

在水渗入干燥和饱和的花岗岩样品过程中,我们观测到了声发射现象和P波速度变化,以此来研究流体诱发地震活动机制。在流体静压力和高偏应力作用下,分别均匀地将水注入干燥和饱和的圆柱体花岗岩端部表面中,用计算机层析技术揭示的二维P波剖面图显示出水前缘皆平行于端部表面,而且在流体静压力作用下,水前缘均匀地离开干燥花岗岩的端部表面。在水注入饱和花岗岩期间,由于受到差应力的作用,岩石内部产生了大量的诱发微裂纹,而对干燥花岗岩却没有产生。声发射源的位置和表面体应变分布显示出诱发微裂纹发生于局部破裂强度较弱的区域。由地下流体流动或水压变化触发的地震活动受控于围岩中既存的原地差应力状态和岩石强度分布。

地球内部没有对流体运动

重新认识地球构造揭开地震成因的关键,只有一步一层去剥离,才能从根本上揭开地震的成因。板块学说起源的理论基础是建立在因:地球内部存在巨大的、有序的对流体运动引起地壳板块断裂移动、相互挤压能量释放产生了地震。该学说还认为:这种流体控制着地球系统的质量和能量的再分配。也因对流体有序运动引起S-N两极磁场诞生。因此、流体学构成了一个完整的地球科研究体系[1]。本篇文章作者在通过较简单模拟试验后发现:1、容器空间内部拥有半液体浓度45~70°两次;2、容器空间内部加压;3、加压至模拟缩小地球内部空间比例的容器空间内。结果:流体屈服于压力!无法运动。结论为:在任何空间内部如拥有半液体、可流体的同时又拥有强大气压时,任何物质都只能屈服于压力。不可能会出现保持几十亿年均衡均速的对流高温溶岩流体、更不会出现一个均衡流速时间不变的地对流运动。因此、现代板块学说起源的理论基础是建立在对流运动的地震成因是错误的。

非岩浆后生热液矿床构造—流体耦合成矿作用研究现状综述

构造—流体耦合成矿作用是矿床学研究的核心问题之一。本文聚焦非岩浆后生热液矿床成矿系统的构造—流体耦合成矿作用研究成果,从构造对流体作用、流体对构造作用两个方面,总结了构造活动与流体作用同步进行且相互影响的机制。通过典型实例分析,认为构造—流体耦合成矿作用研究要从时间、空间、物质方面的耦合关系阐明构造与流体成矿作用过程及其“矿源—输运—聚集”过程,揭示构造活动与流体成矿作用机理。在此基础上,提出了构造—流体耦合成矿作用研究的主要方向及发展趋势。该研究对丰富热液矿床成因理论研究和成矿规律的认识具有重要意义。

Effect of melt convection on primary dendrite arm spacing in directionally solidified Pb-26%Bi hypo-peritectic alloys

Primary dendrite arm spacing（PDAS） of α phase in directionally solidified Pb-26%Bi（mass fraction） hypo-peritectic alloys was measured by considering the effect of melt convection in cylindrical samples with different diameters.The experimental results show the measured PDAS increases with increasing diameter of the sample.At the growth velocity of 5 μm/s,its value changes from 161.5 μm for the sample with 1.8 mm in diameter to 240.4 μm for the sample with 7 mm in diameter.The strong melt convection in large diameter samples causes a high bulk alloy composition and a high concentration gradient in peritectic β phase,resulting in a larger PDAS.Simultaneously,the high concentration gradient could effectively promote the peritectic transformation,enhancing the dissolution of the thin α dendrite.

关于理想教师的思考——谈谈对未来教师基本规格的要求

众所周知,教育对经济发展,经济增长和生产率有着直接的积极影响.教育将是决定人类未来命运的重要领域.办教育尽管有许多工作要做,但培养教师、提高教师水平是第一位的工作.“名师出高徒”,要培养高质量的学中,就要有高水平的教师,从教师职业活动同人类社会发展关系以及教师劳动的特殊性来看,教师是人类思想、道德、文化传播和发展的中介入.继承发展人类文化的优秀成果,开发人类的智力资源,维护和推动人类社会的发展,促进人类自身的完善 这是教师应该发挥的作用.随着社会的发展, 对教师的要求将越来越高.新产业革命的出现,要求教育与现代化大经济(社会化大生产)、社会主义商品经济的发展相适应.这就决定教师素质的特定内容将有很大变化.

喝咖啡能防止胆结石

路透社公布的一项研究结果表明,每天喝两杯含咖啡因的咖啡可以使人减少患胆结石的可能性,这显然是因为咖啡因可以防止胆结石的形成。 哈佛大学研究人员得出结论:咖啡可以防止成年人形成结石,但是他们并没有建议人们多喝咖啡。

Analysis of a Wenzhou-Hitting Exceptionally Strong Rainstorm Associated with a Typhoon Inverted Trough in September,1999

Using T106 numerical products, MM5 simulations in conjunction of Q-vector scheme-computed NCEP results, observations and satellite cloud images, study is undertaken for an exceptionally intense rainstorm event afflicting the Wenzhou region of Zhejiang province far away from the tropical storm center happening early on the morning of September 4, 1999 （TS9909 hereinafter）. Evidence suggests that, like previously-studied typhoons landing in autumn south of Xiamen to the eastern part of Guangdong, TS9909 has an inverted trough in the central south of the coastal belt of Zhejiang province that produces the rainstorm from the meso convective complex （MCC） on the warm, moist shear inside; the time and order of the magnitude of the rainfall are bound up with the development of the pattern of strong Q-vector divergence gradients during the event for the study area; the NE - SW coastline and the unique topography of the Yandang mountains inside the region are favorable for air lifting are the major contributors to the torrential rains.

Hydrodynamic Instabilities Driven by Acid-base Neutralization Reaction in Immiscible System

The hydrodynamic instabilities driven by an acid-base neutralization reaction, in contact along a plane interface, placed in a Hele-Shaw cell under the gravitational field are reported. The system consists of the heavier aqueous tetramethyle-ammonium hydroxide below the lighter layer of organic phase with propionic acid as reacting specie. The effect of chemical composition on hydrodynamic instabilities during interfacial mass transfer accompanied by a neutralization reaction is investigated. Depending on the initial concentration of the reacting species, Marangoni convection in the form of roll ceils or trains of waves is observed. Mach- Zehnder interferometer is used to measure the change in base concentration at the time of instability formation. The results show that the instabilities resulted from the convection flow are more efficient to the mechanism of mass transfer and can drastically alter pattern formation in the system.

An Experimental Study on Nanofluids Convective Heat Transfer Through a Straight Tube under Constant Heat Flux

In this work, the laminar convective heat transfer performance and the pressure drop of water-based nanofluids containing Al2O3, TiO2 and SiO2 nanoparticles flowing through a straight circular tube were experimentally investigated. The experimental results showed that addition of small amounts of nano-sized Al2O3 and TiO2 particles to de-ionized water increased heat transfer coefficients considerably, while the SiO2 nanofluids showed the opposite behavior attracting the authors' interests. An average of 16% and 8.2% increase in heat transfer coefficient were observed with the average of 28% and 15% penalty in pressure drop for Al2O3 and TiO2 nanofluids.

CFD investigation of effect of nanofluid filled Trombe wall on 3D convective heat transfer

A numerical investigation was carried out on the effect of carbon nanotube(CNT)-water-nanofluid-filled Trombe wall on heat transfer and fluid flow inside a 3 D typical room.Time depending governing equations are considered with applying hot temperature at the left surface(collector) of the Trombe wall.The left wall(glazing) of the room and a square part(window) at the right wall are considered at cold temperature.The effects of Rayleigh number and the nanofluid volume fractions and the Trombe wall height on the temperature field,flow structure and heat transfer rate,are studied.The results show that the addition of nanoparticles and the increase of the Trombe wall height,enhance the heat transfer considerably and affect the flow structure and the temperature field.

Finite element modeling of convective pore-fluid flow in fluid-saturated porous rocks within upper crust:An overview

Convective pore-fluid flow (CPFF) plays a critical role in generating mineral deposits and oil reservoirs within the deep Earth. Therefore, theoretical understanding and numerical modeling of the thermodynamic process that triggers and controls the CPFF are extremely important for the exploration of new mineral deposits and underground oil resources. From the viewpoint of science, the CPFF within the upper crust can be treated as a kind of thermodynamic instability problem of pore-fluid in fluid-saturated porous media. The key issue of dealing with this kind of problem is to assess whether a nonlinear thermodynamic system under consideration is supercritical. To overcome limitations of using theoretical analysis and experimental methods in dealing with the CPFF problems within the upper crust, finite element modeling has been broadly employed for solving this kind of problem over the past two decades. The main purpose of this paper is to overview recent developments and applications of finite element modeling associated with solving the CPFF problems in large length-scale geological systems of complicated geometries and complex material distributions. In particular, two kinds of commonly-used finite element modeling approaches, namely the steady-state and transient-state approaches, and their advantages/disadvantages are thoroughly presented and discussed.

Swimming of motile gyrotactic microorganisms and suspension of nanoparticles in a rheological Jeffery fluid with Newtonian heating along elastic surface

Bioconvection plays an inevitable role in introducing sustainable and environment-friendly fuel cell technologies.Bio-mathematical modelling of such designs needs continuous refinements to achieve strong agreements in experimental and computational results.Actually,microorganisms transport a miscellaneous palette of ingredients in manufacturing industrial goods particularly in fertilizer industries.Heat transfer characteristics of molecular structure are measured by a physical phenomenon which is allied with the transpiration of heat within matter.Motivated by bioinspired fuel cells involved in near-surface flow phenomena,in the present article,we examine the transverse swimming of motile gyrotactic microorganisms numerically in a rheological Jeffery fluid near a stretching wall.The leading physical model is converted in a nonlinear system of ODEs through proper similarity alterations.A numerical technique called shooting method with R-K Fehlberg is applied via mathematical software and graphical presentations are obtained.The influence of all relative physical constraints on velocity,temperature,concentration,and volume fraction of gyrotactic microorganisms is expressed geometrically.It is found that heat and mass flux at the surface as well as density of motile microorganism’s declines for Brownian motion and thermophoresis parameter.Comparison in tabular form is made with existing literature to validate the results for limiting cases with convective boundary conditions.

Numerical simulation of the hydrodynamics within octagonal tanks in recirculating aquaculture systems

A three-dimensional numerical model was established to simulate the hydrodynamics within an octagonal tank of a recirculating aquaculture system. The realizable k-e turbulence model was applied to describe the flow, the discrete phase model （DPM） was applied to generate particle trajectories, and the governing equations are solved using the finite volume method. To validate this model, the numerical results were compared with data obtained from a full-scale physical model. The results show that： （1） the realizable k-e model applied for turbulence modeling describes well the flow pattern in octagonal tanks, giving an average relative error of velocities between simulated and measured values of 18% from contour maps of velocity magnitudes; （2） the DPM was applied to obtain particle trajectories and to simulate the rate of particle removal from the tank. The average relative error of the removal rates between simulated and measured values was 11%. The DPM can be used to assess the self-cleaning capability of an octagonal tank; （3） a comprehensive account of the hydrodynamics within an octagonal tank can be assessed from simulations. The velocity distribution was uniform with an average velocity of 15 cm/s; the velocity reached 0.8 m/s near the inlet pipe, which can result in energy losses and cause wall abrasion; the velocity in tank corners was more than 15 cm/s, which suggests good water mixing, and there was no particle sedimentation. The percentage of particle removal for octagonal tanks was 90% with the exception of a little accumulation of 〈5 mm particle in the area between the inlet pipe and the wall. This study demonstrated a consistent numerical model of the hydrodynamics within octagonal tanks that can be further used in their design and optimization as well as promote the wide use of computational fluid dynamics in aquaculture engineering.

Adomian decomposition method simulation of von Kármán swrling bioconvection nanofluid flow

The study reveals analytically on the 3-dimensional viscous time-dependent gyrotactic bioconvection in swirling nanofluid flow past from a rotating disk.It is known that the deformation of the disk is along the radial direction.In addition to that Stefan blowing is considered.The Buongiorno nanofluid model is taken care of assuming the fluid to be dilute and we find Brownian motion and thermophoresis have dominant role on nanoscale unit.The primitive mass conservation equation,radial,tangential and axial momentum,heat,nano-particle concentration and micro-organism density function are developed in a cylindrical polar coordinate system with appropriate wall(disk surface)and free stream boundary conditions.This highly nonlinear,strongly coupled system of unsteady partial differential equations is normalized with the classical von Kármán and other transformations to render the boundary value problem into an ordinary differential system.The emerging 11th order system features an extensive range of dimensionless flow parameters,i.e.,disk stretching rate,Brownian motion,thermophoresis,bioconvection Lewis number,unsteadiness parameter,ordinary Lewis number,Prandtl number,mass convective Biot number,Péclet number and Stefan blowing parameter.Solutions of the system are obtained with developed semi-analytical technique,i.e.,Adomian decomposition method.Validation of the said problem is also conducted with earlier literature computed by Runge-Kutta shooting technique.

Laminar natural convection characteristics in an enclosure with heated hexagonal block for non-Newtonian power law fluids

This work illustrates the steady state, two dimensional natural convective flow and heat transfer features in square enclosure containing heated hexagonal block maintained either at constant wall temperature(CWT) or uniform heat flux(UHF) thermal conditions. Governing equations(mass, momentum and energy) are solved by using finite volume method(FVM) with 3rd order accurate QUICK discretization scheme and SIMPLE algorithm for range of field pertinent parameters such as, Grashof number(10~3≤ Gr ≤ 10~6), Prandtl number(1 ≤ Pr ≤ 100) and power law index(0.5 ≤ n ≤ 1.5). The analysis of momentum and heat transfer characteristics are delineated by evolution of streamlines, isotherms, variation of average Nusselt number value and Colburn factor for natural convection(j_(nH)). A remarkable change is observed on fluid flow and thermal distribution pattern in cavity for both thermal conditions. Nusselt number shows linear variation with Grashof and Prandtl numbers; while rate of heat transfer by convection decreases for power law index value. Higher heat transfer rate can be achieved by using uniform heat flux condition. A Nusselt number correlation is developed for possible utilization in engineering/scientific design purpose.

Introduction to the Turbulent Flows Theory An Axially-Symmetric Peaceful Flows

This paper introduces to fluid state physics （fluid mechanics） a new interpretation of physical phenomena taking place in a fluid in motion. It introduces the base of a new theory claiming that every flow has its own internal structure of motion, which is definite organization of motion, rather than a ＂molecular chaos＂, known from the fluid statics. The paper introduces the new notion of structures vector fields of power and momentum and shows every Newtonian fluid flows are dual in character. It shows that the flow of Newtonian fluid has a dual character. It demonstrates on models and further in mathematical interpretation of physical phenomena. It introduces, on the one hand, the cycloidal motion model into the fluid mechanics, ad on the other hand an addition to the known, the classical model of Poiseuille laminar motion. The theory of dualism （double nature of physical phenomena） allows the description of selected characteristics of the flow, either by using the theory ofcycloidal motion （semicycloidal）, or by using the supplemented theory of laminar motion. The dualism theory is useful to describe each type of flows both, laminar and turbulent. This paper is only an introduction to the theory. It has been assigned number 1. It has been granted a high priority, since it contains basic concepts that will be used in others, following papers of long cycle.

Peristaltic transport of MHD Williamson fluid in an inclined asymmetric channel through porous medium with heat transfer

The intention of this investigation is to study the effects of heat transfer and inclined magnetic field on the peristaltic flow of Williamson fluid in an asymmetric channel through porous medium. The governing two-dimensional equations are simplified under the assumption of long wavelength approximation. The simplified equations are solved for the stream function, temperature, and axial pressure gradient by using a regular perturbation method. The expression for pressure rise is computed numerically. The profiles of velocity, pressure gradient, temperature, heat transfer coefficient and stream function are sketched and interpreted for various embedded parameters and also the behavior of stream function for various wave forms is discussed through graphs. It is observed that the peristaltic velocity increases from porous medium to non-porous medium, the magnetic effects have increasing effect on the temperature, and the size of the trapped bolus decreases with the increasing of magnetic effects while the trend is reversed with the increasing of Darcy number. Moreover, limiting solutions of our problem are in close agreement with the corresponding results of the Newtonian fluid model.

Electrical conductivity effect on MHD mixed convection of nanofluid flow over a backward-facing step

In this study,magneto-hydrodynamics (MHD) mixed convection effects of Al2O3-water nanofluid flow over a backward-facing step were investigated numerically for various electrical conductivity models of nanofluids.A uniform external magnetic field was applied to the flow and strength of magnetic field was varied with different values of dimensionless parameter Hartmann number (Ha=0,10,20,30,40).Three different electrical conductivity models were used to see the effects of MHD nanofluid flow.Besides,five different inclination angles between 0°-90° is used for the external magnetic field.The problem geometry is a backward-facing step which is used in many engineering applications where flow separation and reattachment phenomenon occurs.Mixed type convective heat transfer of backward-facing step was examined with various values of Richardson number (Ri=0.01,0.1,1,10) and four different nanoparticle volume fractions (Ф=0.01,0.015,0.020,0.025) considering different electrical conductivity models.Finite element method via commercial code COMSOL was used for computations.Results indicate that the addition of nanoparticles enhanced heat transfer significantly.Also increasing magnetic field strength and inclination angle increased heat transfer rate.Effects of different electrical conductivity models were also investigated and it was observed that they have significant effects on the fluid flow and heat transfer characteristics in the presence of magnetic field.

Flow of Casson nanofluid with viscous dissipation and convective conditions: A mathematical model

The magnetohydrodynamic(MHD) boundary layer flow of Casson fluid in the presence of nanoparticles is investigated.Convective conditions of temperature and nanoparticle concentration are employed in the formulation. The flow is generated due to exponentially stretching surface. The governing boundary layer equations are reduced into the ordinary differential equations. Series solutions are presented to analyze the velocity, temperature and nanoparticle concentration fields. Temperature and nanoparticle concentration fields decrease when the values of Casson parameter enhance. It is found that the Biot numbers arising due to thermal and concentration convective conditions yield an enhancement in the temperature and concentration fields. Further, we observed that both the thermal and nanoparticle concentration boundary layer thicknesses are higher for the larger values of thermophoresis parameter. The effects of Brownian motion parameter on the temperature and nanoparticle concentration are reverse.