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Sample records for earth pressure balance

  1. Earth pressure balance control for EPB shield

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    This paper mainly deals with the critical technology of earth pressure balance (EPB) control in shield tunneling. On the assumption that the conditioned soil in the working chamber of the shield is plasticized, a theoretical principle for EPB control is proposed. Dynamic equilibrium of intake volume and discharge volume generated by thrust and discharge is modeled theoretically to simulate the earth pressure variation during excavating. The thrust system and the screw conveyor system for earth pressure control are developed based on the electro-hydraulic technique. The control models of the thrust speed regulation of the cylinders and the rotating speed adjustment of the screw conveyor are also presented. Simulation for earth pressure control is conducted with software AMESim and MATLAB/Simulink to verify the models. Experiments are carried out with intake control in clay soil and discharge control in sandy gravel section, respectively. The experimental results show that the earth pressure variations in the working chamber can be kept at the expected value with a practically acceptable precision by means of real-time tuning the thrust speed or the revolving speed of discharge system.

  2. Experimental study on working parameters of earth pressure balance shield machine tunneling in soft ground

    Institute of Scientific and Technical Information of China (English)

    Hehua ZHU; Shaoming LIAO; Qianwei XU; Qizhen ZHENG

    2008-01-01

    Deep sedimentary deposits of soft clays are widely distributed in coastal areas as well as many interior major cities in China. In order to study the stratum adapt-ability of earth pressure balance (EPB) shield machine tunneling in such types of soft ground, model tests of tunneling excavation, using the running tunnel of the Shanghai Metro Line M8 as a background, are carried out with different over burden ratios, opening rates of cutter head, driving speeds and rotation speeds of screw conveyor. Based on the test results, the interrelationships between chamber pressure and mucking efficiency, muck-ing rate and driving speed, thrust force and torque are obtained. The influences of tunnel depth, opening rate of cutter head and driving speed on thrust force and tor-que are revealed. Such findings can not only facilitate establishing relationships between shield working para-meters and soil properties, but also serve as a guide for the design and construction of shield tunnel in soft ground.

  3. Pressure regulation for earth pressure balance control on shield tunneling machine by using adaptive robust control

    Science.gov (United States)

    Xie, Haibo; Liu, Zhibin; Yang, Huayong

    2016-05-01

    Most current studies about shield tunneling machine focus on the construction safety and tunnel structure stability during the excavation. Behaviors of the machine itself are also studied, like some tracking control of the machine. Yet, few works concern about the hydraulic components, especially the pressure and flow rate regulation components. This research focuses on pressure control strategies by using proportional pressure relief valve, which is widely applied on typical shield tunneling machines. Modeling of a commercial pressure relief valve is done. The modeling centers on the main valve, because the dynamic performance is determined by the main valve. To validate such modeling, a frequency-experiment result of the pressure relief valve, whose bandwidth is about 3 Hz, is presented as comparison. The modeling and the frequency experimental result show that it is reasonable to regard the pressure relief valve as a second-order system with two low corner frequencies. PID control, dead band compensation control and adaptive robust control (ARC) are proposed and simulation results are presented. For the ARC, implements by using first order approximation and second order approximation are presented. The simulation results show that the second order approximation implement with ARC can track 4 Hz sine signal very well, and the two ARC simulation errors are within 0.2 MPa. Finally, experiment results of dead band compensation control and adaptive robust control are given. The results show that dead band compensation had about 30° phase lag and about 20% off of the amplitude attenuation. ARC is tracking with little phase lag and almost no amplitude attenuation. In this research, ARC has been tested on a pressure relief valve. It is able to improve the valve's dynamic performances greatly, and it is capable of the pressure control of shield machine excavation.

  4. Earth Pressure on Tunnel Crown

    DEFF Research Database (Denmark)

    Andersen, Lars

    Two different analyses have been carried out in order to find the vertical earth pressure, or overburden pressure, at the crown of a tunnel going through a dike. Firstly, a hand calculation is performed using a simple dispersion of the stresses over depth. Secondly, the finite‐element program...

  5. Pressure-Balance Consistency in Magnetospheric Modelling

    Institute of Scientific and Technical Information of China (English)

    肖永登; 陈出新

    2003-01-01

    There have been many magnetic field models for geophysical and astrophysical bodies.These theoretical or empirical models represent the reality very well in some cases,but in other cases they may be far from reality.We argue that these models will become more reasonable if they are modified by some coordinate transformations.In order to demonstrate the transformation,we use this method to resolve the "pressure-balance inconsistency"problem that occurs when plasma transports from the outer plasma sheet of the Earth into the inner plasma sheet.

  6. 土压平衡盾构机刀盘刀具布置方法研究%Research on Cutting Tool Layout Method of Earth Pressure Balance Shield

    Institute of Scientific and Technical Information of China (English)

    蒲毅; 刘建琴; 郭伟; 裴瑞英

    2011-01-01

    To ensure rationality and practicability of the cutter configuration, it is necessary to propose the method of cutting tool layout of earth pressure balance (EPB) shield. According to the equal-life principle of tool wear, the wear coefficient method and tunneling coefficient method are proposed to determine the number of tools; When it comes to a specific construction, it also can predict tool wear condition and the tunneling distance under the allowable attrition in the range of the shield tunnel excavation, which offer a reference for the safety of project; Based on Archimedes spiral layout method, the arrangement curve of drag bits on cutter head should be calculated according to the equal-life principle of tool wear; In order to obtain the actual depth of a cutting tool, the rule of plane symmetry layout of the cutting tool is put forward, and cutting process is analyzed; the first knife's three-dimensional arrangement method of the EPB shield is established, the actual cutting depth of a single tool is obtained; The accuracy of the cutting tool layout theory above is investigated with the example of TA07 of Nanjing Metro number two line. The research content and method lay a theoretical foundation for the EPB shield cutter selection and design theory.%研究土压平衡(Earth pressure balanced,EPB)盾构机刀盘刀具的布置方法,目的是为了确保刀具结构布置的合理性和实用性.依据刀具磨损的等寿命原则,提出确定刀具数量的磨损系数法和掘进系数法;针对具体施工问题,可预测盾构在开挖区间,刀具的磨损量以及许用磨损情况下刀具的掘进距离,为保障工程的安全顺利进行提供参考.基于阿基米德螺旋线布置方法,计算以刀具磨损的等寿命原则下,主切削刀的布置曲线;提出刀具平面对称布局原则,分析刀具的切削过程,得到单把刀具的实际切深;建立EPB盾构刀盘上先行刀的立体布局方法,计算得到先行刀的超前

  7. Dynamic active earth pressure on retaining structures

    Indian Academy of Sciences (India)

    Deepankar Choudhury; Santiram Chatterjee

    2006-12-01

    Earth-retaining structures constitute an important topic of research in civil engineering, more so under earthquake conditions. For the analysis and design of retaining walls in earthquake-prone zones, accurate estimation of dynamic earth pressures is very important. Conventional methods either use pseudo-static approaches of analysis even for dynamic cases or a simple single-degree of freedom model for the retaining wall–soil system. In this paper, a simplified two-degree of freedom mass–spring–dashpot (2-DOF) dynamic model has been proposed to estimate the active earth pressure at the back of the retaining walls for translation modes of wall movement under seismic conditions. The horizontal zone of influence on dynamic earth force on the wall is estimated. Results in terms of displacement, velocity and acceleration-time history are presented for some typical cases, which show the final movement of the wall in terms of wall height, which is required for the design. The non-dimensional design chart proposed in the present study can be used to compute the total dynamic earth force on the wall under different input ground motion and backfill conditions. Finally, the results obtained have been compared with those of the available Scott model and the merits of the present results have been discussed.

  8. The energy balance of the earth' surface : a practical approach

    NARCIS (Netherlands)

    Bruin, de H.A.R.

    1982-01-01

    This study is devoted to the energy balance of the earth's surface with a special emphasis on practical applications. A simple picture of the energy exchange processes that take place at the ground is the following. Per unit time and area an amount of radiant energy is supplied to the surface. This

  9. High-pressure investigations of Earth's interior

    Science.gov (United States)

    Jackson, Jennifer

    2007-03-01

    In the first half of the talk, the electronic structure of iron in ferromagnesium silicate perovskite will be discussed. Knowledge of iron valences and spin states in silicate perovskite is relevant to our understanding of the physical and chemical properties of Earth's lower mantle such as transport properties, mechanical behavior, and element partitioning. In this study, we have measured the electronic structure of the iron component of an aluminous Fe-bearing silicate perovskite sample, (Mg0.88Fe0.09)(Si0.94Al0.10)O3, close to a pyrolite composition, using synchrotron M"ossbauer spectroscopy (SMS) and laser heated diamond anvil cells at high-pressure and temperatures at beamline 3-ID of the Advanced Photon Source. Evaluation of the spectra provided the isomer shift and the quadrupole splitting of the iron component in silicate perovskite, which gives information on valence and spin states under lower mantle conditions. In the second half of the talk, experiments on the melting curve of iron at high-pressures will be presented. Seismological observations indicate that Earth's iron-dominated core consists of a solid inner region surrounded by a liquid outer core. Previously, melting studies of iron metal at high-pressures and temperatures were performed by shock-compression, resistive- and laser-heating in diamond anvil cells using visual observations or synchrotron x-ray diffraction and theoretical methods. However, the melting curve of iron is still controversial. Here, we will present a new method of detecting the solid-liquid phase boundary of iron at high-pressure using ^57Fe SMS. The characteristic SMS time signature is observed by fast detectors and vanishes suddenly when melting occurs. This process is described by the Lamb-M"ossbauer factor f = exp(-k^2), where k is the wave number of the resonant x-rays and is the mean-square displacement of the iron atoms.

  10. Blood pressure associates with standing balance in elderly outpatients.

    Directory of Open Access Journals (Sweden)

    Jantsje H Pasma

    Full Text Available OBJECTIVES: Assessment of the association of blood pressure measurements in supine and standing position after a postural change, as a proxy for blood pressure regulation, with standing balance in a clinically relevant cohort of elderly, is of special interest as blood pressure may be important to identify patients at risk of having impaired standing balance in routine geriatric assessment. MATERIALS AND METHODS: In a cross-sectional cohort study, 197 community-dwelling elderly referred to a geriatric outpatient clinic of a middle-sized teaching hospital were included. Blood pressure was measured intermittently (n = 197 and continuously (subsample, n = 58 before and after a controlled postural change from supine to standing position. The ability to maintain standing balance was assessed during ten seconds of side-by-side, semi-tandem and tandem stance, with both eyes open and eyes closed. Self-reported impaired standing balance and history of falls were recorded by questionnaires. Logistic regression analyses were used to examine the association between blood pressure and 1 the ability to maintain standing balance; 2 self-reported impaired standing balance; and 3 history of falls, adjusted for age and sex. RESULTS: Blood pressure decrease after postural change, measured continuously, was associated with reduced ability to maintain standing balance in semi-tandem stance with eyes closed and with increased self-reported impaired standing balance and falls. Presence of orthostatic hypotension was associated with reduced ability to maintain standing balance in semi-tandem stance with eyes closed for both intermittent and continuous measurements and with increased self-reported impaired standing balance for continuous measurements. CONCLUSION: Continuous blood pressure measurements are of additional value to identify patients at risk of having impaired standing balance and may therefore be useful in routine geriatric care.

  11. Water balance of an earth fill built of organic clay

    Directory of Open Access Journals (Sweden)

    Birle Emanuel

    2016-01-01

    Full Text Available The paper presents investigations on the water balance of an earth fill built of organic clay in humid climate. As the organic soil used for the fill contains geogenetically elevated concentrations of arsenic, particular attention is paid on the seepage flow through the fill. The test fill is 5 m high, 30 m long and 25 m wide. The fill consists of the organic clay compacted at water contents wet and dry of Proctor Optimum covered by a drainage mat and a 60 cm thick top layer. For the determination of the water balance extensive measuring systems were installed. The seepage at the bottom measured so far was less than 2 % of the precipitation. The interflow in the drainage mat above the compacted organic clay was of similar magnitude. The estimated evapotranspiration reached approx. 84 % of the precipitation. According to these measurements the percolation is much lower than the percolation of many landfill covers in humid climates.

  12. Rigidly framed earth retaining structures thermal soil structure interaction of buildings supporting unbalanced lateral earth pressures

    CERN Document Server

    Aboumoussa, Walid

    2014-01-01

    Structures placed on hillsides often present a number of challenges and a limited number of economical choices for site design. An option sometimes employed is to use the building frame as a retaining element, comprising a Rigidly Framed Earth Retaining Structure (RFERS). The relationship between temperature and earth pressure acting on RFERS, is explored in this monograph through a 4.5 year monitoring program of a heavily instrumented in service structure. The data indicated that the coefficient of earth pressure behind the monitored RFERS had a strong linear correlation with temperature. The study also revealed that thermal cycles, rather than lateral earth pressure, were the cause of failure in many structural elements. The book demonstrates that depending on the relative stiffness of the retained soil mass and that of the structural frame, the developed lateral earth pressure, during thermal expansion, can reach magnitudes several times larger than those determined using classical earth pressure theories....

  13. Physical Limitations of Empirical Field Models: Force Balance and Plasma Pressure

    Energy Technology Data Exchange (ETDEWEB)

    Sorin Zaharia; C.Z. Cheng

    2002-06-18

    In this paper, we study whether the magnetic field of the T96 empirical model can be in force balance with an isotropic plasma pressure distribution. Using the field of T96, we obtain values for the pressure P by solving a Poisson-type equation {del}{sup 2}P = {del} {center_dot} (J x B) in the equatorial plane, and 1-D profiles on the Sun-Earth axis by integrating {del}P = J x B. We work in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials. Our results lead to the conclusion that the T96 model field cannot be in equilibrium with an isotropic pressure. We also analyze in detail the computation of Birkeland currents using the Vasyliunas relation and the T96 field, which yields unphysical results, again indicating the lack of force balance in the empirical model. The underlying reason for the force imbalance is likely the fact that the derivatives of the least-square fitted model B are not accurate predictions of the actual magnetospheric field derivatives. Finally, we discuss a possible solution to the problem of lack of force balance in empirical field models.

  14. Economics as if the earth really mattered. Putting balance back on the balance sheet.

    Science.gov (United States)

    Sherman, D

    1991-09-01

    Some of the thinking in the economic realm which affects the relationship between the economy and the environment is discussed. The standard economic model inherently conflicts with the environment. Humans as consumers have their needs met by maximizing production and efficiency in a free market economy, where an invisible hand guides to profit. The question is raised as to what the environmental impact is for economic growth. The need for clean air, water, and preservation of other living things is not met. It is argued that pollution is a necessary byproduct of production. Economic progress as measured by gross national product (GNP) cannot account for the degradation of nature, e.g., the Alaskan oil spill actually increased GNP. Traditional economics also tell little about the maldistribution of wealth. It is pointed out that Americans spend $5 billion a year on special diets while 400 million around the world are undernourished. Limits to natural resources are also not accounted for by economic theorists, or the value of the seemingly free life-sustaining services performed by a forest in purifying air, preventing erosion and flooding, regulating climate, and supporting biological diversity. It is pointed out that restructuring must occur if the capacity of the Earth to support life is classed in economic terms as an externality. Steady state economic models consider the cycles of production and consumption in the context of the surrounding ecosystem of waste and raw materials and try to achieve a state of equilibrium. Despite the 1972 President's Commission on Population Growth and the American Future's statement that population growth is not necessary for a vital economy, the mythology exists that the economy will collapse, personal income will drop, and business will decline without an ever-growing population. A summary on positive outcomes of zero population growth is given. The economist Julian Simon promotes the view that there is no environmental

  15. Pressure-temperature Phase Diagram of the Earth

    CERN Document Server

    Jones, Eriita

    2010-01-01

    Based on a pressure-temperature (P-T) phase diagram model of the Earth, Jones & Lineweaver (2010) described uninhabited terrestrial liquid water. Our model represents the atmosphere, surface, oceans and interior of the Earth - allowing the range of P-T conditions in terrestrial environments to be compared to the phase regime of liquid water. Here we present an overview and additional results from the Earth model on the location of the deepest liquid water on Earth and the maximum possible extent of the terrestrial biosphere. The intersection of liquid water and terrestrial phase space indicates that the deepest liquid water environments in the lithosphere occur at a depth of ~ 75 km. 3.5 % of the volume of the Earth is above 75 km depth. Considering the 3.5 % of the volume of the Earth where liquid water exists, ~ 12% of this volume is inhabited by life while the remaining ~ 88% is uninhabited. This is distinct from the fraction of the volume of liquid water occupied by life. We find that at least 1% of t...

  16. COMPUTER SIMULATION OF VENTILATION PRESSURE BALANCING FOR THE PREVENTION OF SPONTANEOUS COMBUSTION IN MINES

    Institute of Scientific and Technical Information of China (English)

    周心权; 吴兵

    1995-01-01

    Qualitative analysis plus trial and error method are still the routine to achieve ventilation pressure balancing. These methods may cause large errors in pressure balancing so that sometimes the spontaneous combustion can not be extnguished effectively. This paper introduces a quantitative analysis of pressure balancing for different causes of ventilation networks and develops a computer program (SPFPB) specifically written for pressure balancing between faces and connected gobs. It allows a user to choose different methods to meet his various needs and the underground conditions. The different balancing results are compared, and the proper locations and sizes of the control devices are recommended.

  17. Pressure-induced exotic states in rare earth hexaborides

    Science.gov (United States)

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  18. Pressure-induced exotic states in rare earth hexaborides.

    Science.gov (United States)

    Sun, Liling; Wu, Qi

    2016-08-01

    Finding the exotic phenomena in strongly correlated electron systems (SCESs) and understanding the corresponding microphysics have long been the research frontiers of condensed matter physics. The remarkable examples for the intriguing phenomena discovered in past years include unconventional superconductivity, heavy Fermion behaviors, giant magneto-resistance and so on. A fascinating type of rare earth hexaboride RB6 (R  =  Sm, Yb, Eu and Ce) belongs to a strongly correlated electron system (SCES), but shows unusual ambient-pressure and high-pressure behaviors beyond the phenomena mentioned above. Particularly, the recent discovery of the coexistence of an unusual metallic surface state and an insulating bulk state in SmB6, known to be a Kondo insulator decades ago, by theoretical calculations and many experimental measurements creates new interest for the investigation of the RB6. This significant progress encourages people to revisit the RB6 with an attempt to establish a new physics that links the SCES and the unusual metallic surface state which is a common feature of a topological insulator (TI). It is well known that pressure has the capability of tuning the electronic structure and modifying the ground state of solids, or even inducing a quantum phase transition which is one of the kernel issues in studies of SCESs. In this brief review, we will describe the progress in high pressure studies on the RB6 based on our knowledge and research interests, mainly focusing on the pressure-induced phenomena in YbB6 and SmB6, especially on the quantum phase transitions and their connections with the valence state of the rare earth ions. Moreover, some related high-pressure results obtained from CeB6 and EuB6 are also included. Finally, a summary is given in the conclusions and perspectives section.

  19. An update on Earth's energy balance in light of the latest global observations

    Science.gov (United States)

    Stephens, Graeme L.; Li, Juilin; Wild, Martin; Clayson, Carol Anne; Loeb, Norman; Kato, Seiji; L'Ecuyer, Tristan; Stackhouse, Paul W.; Lebsock, Matthew; Andrews, Timothy

    2012-10-01

    Climate change is governed by changes to the global energy balance. At the top of the atmosphere, this balance is monitored globally by satellite sensors that provide measurements of energy flowing to and from Earth. By contrast, observations at the surface are limited mostly to land areas. As a result, the global balance of energy fluxes within the atmosphere or at Earth's surface cannot be derived directly from measured fluxes, and is therefore uncertain. This lack of precise knowledge of surface energy fluxes profoundly affects our ability to understand how Earth's climate responds to increasing concentrations of greenhouse gases. In light of compilations of up-to-date surface and satellite data, the surface energy balance needs to be revised. Specifically, the longwave radiation received at the surface is estimated to be significantly larger, by between 10 and 17 Wm-2, than earlier model-based estimates. Moreover, the latest satellite observations of global precipitation indicate that more precipitation is generated than previously thought. This additional precipitation is sustained by more energy leaving the surface by evaporation -- that is, in the form of latent heat flux -- and thereby offsets much of the increase in longwave flux to the surface.

  20. THE HABITABLE ZONE OF EARTH-LIKE PLANETS WITH DIFFERENT LEVELS OF ATMOSPHERIC PRESSURE

    Energy Technology Data Exchange (ETDEWEB)

    Vladilo, Giovanni; Murante, Giuseppe; Silva, Laura [INAF-Trieste Astronomical Observatory, Trieste (Italy); Provenzale, Antonello [Institute of Atmospheric Sciences and Climate-CNR, Torino (Italy); Ferri, Gaia; Ragazzini, Gregorio, E-mail: vladilo@oats.inaf.it [Department of Physics, University of Trieste, Trieste (Italy)

    2013-04-10

    As a contribution to the study of the habitability of extrasolar planets, we implemented a one-dimensional energy balance model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p = 1/3 to 3 bar. At low pressure, the habitability is low and varies with a; at high pressure, the habitability is high and relatively constant inside the HZ. We interpret these results in terms of the pressure dependence of the greenhouse effect, the efficiency of horizontal heat transport, and the extent of the liquid water temperature range. Within the limits discussed in the paper, the results can be extended to planets in eccentric orbits around non-solar-type stars. The main characteristics of the pressure-dependent HZ are modestly affected by variations of planetary properties, particularly at high pressure.

  1. The habitable zone of Earth-like planets with different levels of atmospheric pressure

    CERN Document Server

    Vladilo, Giovanni; Silva, Laura; Provenzale, Antonello; Ferri, Gaia; Ragazzini, Gregorio

    2013-01-01

    As a contribution to the study of the habitability of extrasolar planets, we implemented a 1-D Energy Balance Model (EBM), the simplest seasonal model of planetary climate, with new prescriptions for most physical quantities. Here we apply our EBM to investigate the surface habitability of planets with an Earth-like atmospheric composition but different levels of surface pressure. The habitability, defined as the mean fraction of the planet's surface on which liquid water could exist, is estimated from the pressure-dependent liquid water temperature range, taking into account seasonal and latitudinal variations of surface temperature. By running several thousands of EBM simulations we generated a map of the habitable zone (HZ) in the plane of the orbital semi-major axis, a, and surface pressure, p, for planets in circular orbits around a Sun-like star. As pressure increases, the HZ becomes broader, with an increase of 0.25 AU in its radial extent from p=1/3 bar to p=3 bar. At low pressure, the habitability is...

  2. INVESTIGATION INTO EFFECT OF SPRING PRESSURE ON PERFORMANCE OF BALANCED MECHANICAL SEALS

    Institute of Scientific and Technical Information of China (English)

    SUN Jianjun; GU Boqin

    2007-01-01

    The loads acting on the sealing elements of balanced mechanical seals are analyzed. When the balance factor approaches the back pressure factor, the spring pressure will become main part of the face pressure. The leakage model of balanced mechanical seals is established on the base of M-B model for rough surface. Several GY-70 type balanced mechanical seals are tested. The influences of the spring pressure both on the leakage rate and on the friction characteristic of balanced mechanical seals are investigated. The research results indicate that as spring pressure increases, both the clearance between two end faces and the leakage rate will decrease, and the friction will be more serious because lubrication medium between the rotating ring and the stationary ring reduces, though the increase of the spring pressure may not be enough to change the face friction state of mechanical seals. There exists an optimum spring pressure for mechanical seal operation. Under this spring pressure, not only leakage rate is small, but also the seal end surfaces have a fine friction characteristic.Under different operating conditions, identical type mechanical seals may possess different spring pressure. Appropriate selection of spring pressure is valuable to realize long-period and small leakage rate operating of balanced mechanical seals.

  3. A Mechanism of Solar Variability Effect on Radiative Balance of the Earth Atmosphere

    Institute of Scientific and Technical Information of China (English)

    G. A. Zherebtsov; V.A. Kovalenko; S.I. Molodykh

    2005-01-01

    Possible mechanisms of solar-climatic connections, which may be of importance as over short and long time intervals, are discussed. The variations of energetic balance of Earth's climatic system for the last fifty years are estimated. It is ascertained that the disbalance between the flux of solar energy that comes to the Earth and radiates to space is of 0.1% for the last ten years. The suggested mechanism makes it possible to explain not only the observed variation of the enthalpy of the Earth's climatic system for the period 1910-1980, but also the climate anomalies during last thousand years: the climate optimum in 12 century, and"small glacial period" in 16-17 centuries.

  4. Dilation effect on 3D Passive Earth Pressure Coefficients for Retaining Wall

    OpenAIRE

    Khelifa, Tarek; Benmebarek, Sadok

    2015-01-01

    The 2D passive earth pressures acting on rigid retaining walls problem has been widely treated in the literature using different approaches (limit equilibrium, limit analysis, slip line and numerical computation), however, the 3D passive earth pressures problem has received less attention. This paper is concerned with the numerical study of 3D passive earth pressures induced by the translation of a rigid rough retaining wall for associated and non-associated soils. Using the explicit finite d...

  5. Dilation effect on 3D Passive Earth Pressure Coefficients for Retaining Wall

    OpenAIRE

    Khelifa, Tarek; Benmebarek, Sadok

    2014-01-01

    The 2D passive earth pressures acting on rigid retaining walls problem has been widely treated in the literature using different approaches (limit equilibrium, limit analysis, slip line and numerical computation), however, the 3D passive earth pressures problem has received less attention. This paper is concerned with the numerical study of 3D passive earth pressures induced by the translation of a rigid rough retaining wall for associated and non-associated soils. Using the explicit finite d...

  6. Research on Cutterhead Torque during Earth Pressure Balance Shield Tunneling in Sand Gravel Strata of Beijing Metro%北京地铁砂卵石地层土压平衡盾构施工刀盘扭矩研究

    Institute of Scientific and Technical Information of China (English)

    江华; 江玉生; 张晋勋; 程学武; 杨志勇

    2013-01-01

    根据砂卵石地层力学特性,结合北京地铁4个标段工程,分析土压平衡盾构刀盘扭矩各组成部分所占的比例,提出简化的刀盘扭矩计算公式.分析计算结果表明:刀盘开口率与刀盘扭矩成反比,开口率每增加10%,刀盘扭矩降低8%~10%;土体的流塑性对刀盘扭矩影响较大;土体的摩擦系数每降低0.1,刀盘扭矩相应降低约35%~40%.在北京地铁10号线二期工程现场进行盾构掘进试验,分别通过刀盘改造(开口率增大至40%)及土体改良,使刀盘扭矩保持在2 500~3 500 kN·m,盾构推进速度明显得到改善.试验结果进一步验证了增大开口率及土体改良是在砂卵石地层降低刀盘扭矩的2项非常有效的措施;也验证了刀盘扭矩计算公式是合理的、可靠的,满足工程实际需求.%According to the mechanical properties of sand gravel strata,and combined with four bid sections engineering of Beijing Metro,the proportions of cutterhead torque in each composition part of earth pressure balance shield were found out,and the simplified formula of cutterhead torque was obtained.Analysis results show that cutterhead opening ratio is inversely proportional to cutterhead torque.Cutterhead torque decreases about 8% to 10% for every increase of 10% in cutterhead opening ratio.Soil fluid plasticity has a great impact on cutterhead torque.For every decrease of 0.1 in soil friction coefficient,cutterhead torque decreases about 35 % to 40 % correspondingly.Shield tunneling tests were carried out in the second phase engineering of Beijing Metro Line 10.By means of cutterhead improving (cutterhead opening ratio is increased to 40%) and soil conditioning respectively,cutterhead torque can be controlled between 2 500 and 3 500 kN · m,and shield advance speed is improved significantly.Test results have further verified that increasing opening ratio and soil conditioning are two very effective measures for reducing

  7. Seismic Earth Pressure Development in Sheet Pile Retaining Walls: A Numerical Study

    CERN Document Server

    Rajeev, P; Sivakugan, N

    2015-01-01

    The design of retaining walls requires the complete knowledge of the earth pressure distribution behind the wall. Due to the complex soil-structure effect, the estimation of earth pressure is not an easy task; even in the static case. The problem becomes even more complex for the dynamic (i.e., seismic) analysis and design of retaining walls. Several earth pressure models have been developed over the years to integrate the dynamic earth pressure with the static earth pressure and to improve the design of retaining wall in seismic regions. Among all the models, MononobeOkabe (M-O) method is commonly used to estimate the magnitude of seismic earth pressures in retaining walls and is adopted in design practices around the world (e.g., EuroCode and Australian Standards). However, the M-O method has several drawbacks and does not provide reliable estimate of the earth pressure in many instances. This study investigates the accuracy of the M-O method to predict the dynamic earth pressure in sheet pile wall. A 2D pl...

  8. Simulation of the Earth's gravitational field recovery from GRACE using the energy balance approach

    Institute of Scientific and Technical Information of China (English)

    ZHENG Wei; LU Xiaolei; HSU Houtse; SHAO Chenggang; LUO Jun; WANG Nengchao

    2005-01-01

    Based on the measurement principles of GRACE satellites, the observation equations are set up using the energy balance approach. The Earth's gravitational field complete up to degree and order 120 is recovered applying the preconditioning conjugate gradient iterative approach by numerical simulation. Assuming an accuracy of 1?m/s in range-rate measurements of the K-band microwave ranging system, the matching relationships of accuracies of K-band microwave ranging system, SuperSTAR Accelerometer, position vector and velocity vector measurements are investigated.

  9. DISTRIBUTION OF ACTIVE EARTH PRESSURE OF RETAINING WALL WITH WALL MOVEMENT OF ROTATION ABOUT TOP

    Institute of Scientific and Technical Information of China (English)

    王元战; 唐照评; 郑斌

    2004-01-01

    Based on the Coulomb' s theory that the earth pressure against the back of a retaining wall is due to the thrust exerted by the sliding wedge of soil from the back of the wall to a plane which passes through the bottom edge of the wall and has an inclination equal to the angle of θ, the theoretical answers to the unit earth pressure, the resultant earth pressure and the point of application of the resultant earth pressure on a retaining wall were obtained for the wall movement mode of rotation about top. The comparisons were made among the formula presented here, the formula for the wall movement mode of translation,the Coulomb' s formula and some experimental observations. It is demonstrated that the magnitudes of the resultant earth pressures for the wall movement mode of rotation about top is equal to that determined by the formula for the wall movement mode of translation and the Coulomb' s theory. But the distribution of the earth pressure and the points of application of the resultant earth pressures have significant difference.

  10. EDITORIAL: The Earth radiation balance as driver of the global hydrological cycle

    Science.gov (United States)

    Wild, Martin; Liepert, Beate

    2010-06-01

    Variations in the intensity of the global hydrological cycle can have far-reaching effects on living conditions on our planet. While climate change discussions often revolve around possible consequences of future temperature changes, the adaptation to changes in the hydrological cycle may pose a bigger challenge to societies and ecosystems. Floods and droughts are already today amongst the most damaging natural hazards, with floods being globally the most significant disaster type in terms of loss of human life (Jonkman 2005). From an economic perspective, changes in the hydrological cycle can impose great pressures and damages on a variety of industrial sectors, such as water management, urban planning, agricultural production and tourism. Despite their obvious environmental and societal importance, our understanding of the causes and magnitude of the variations of the hydrological cycle is still unsatisfactory (e.g., Ramanathan et al 2001, Ohmura and Wild 2002, Allen and Ingram 2002, Allan 2007, Wild et al 2008, Liepert and Previdi 2009). The link between radiation balance and hydrological cycle Globally, precipitation can be approximated by surface evaporation, since the variability of the atmospheric moisture storage is negligible. This is the case because the fluxes are an order of magnitude larger than the atmospheric storage (423 x 1012 m3 year-1 versus 13 x 1012 m3 according to Baumgartner and Reichel (1975)), the latter being determined by temperature (Clausius-Clapeyron). Hence the residence time of evaporated water in the atmosphere is not more than a few days, before it condenses and falls back to Earth in the form of precipitation. Any change in the globally averaged surface evaporation therefore implies an equivalent change in precipitation, and thus in the intensity of the global hydrological cycle. The process of evaporation requires energy, which it obtains from the surface radiation balance (also known as surface net radiation), composed of the

  11. Heterogeneous Earth Accretion and Incomplete Metal-Silicate Reequilibration at High Pressure During Core Formation

    Science.gov (United States)

    Rubie, D. C.; Mann, U.; Frost, D. J.; Kegler, P.; Holzheid, A.; Palme, H.

    2007-12-01

    We present a new model of core formation, based on the partitioning of siderophile elements, that involves accreting the Earth through a series of collisions with smaller bodies that had already differentiated at low pressure. Each impact results in a magma ocean in which the core of the impactor reequilibrates with silicate liquid at high pressure before merging with the Earth's protocore. The oxygen contents of the chondritic compositions of the proto-Earth and impactors can be varied. The compositions of coexisting metal and silicate are determined through mass balance combined with partitioning equations for Ni, FeO, Si and other siderophile elements. The oxygen fugacity is fixed by the partitioning of FeO and is a function of P, T and bulk oxygen content. An important constraint for core formation is that core-mantle partition coefficients for Ni and Co must both converge to values of 23-28. Based on a recent study of the partitioning of Ni and Co over a wide P-T range (Kegler et al., EPSL, submitted) together with other published data, this constraint is not satisfied by a single- stage core formation model at any conditions because the partition coefficients converge at values that are much too low. In the present multi-stage model, the correct values can be reached if only part of each impactor core reequilibrates with silicate liquid in the magma ocean (as proposed by previous models based on Hf-W isotope studies). Physically, this would mean that impactor cores fail to emulsify completely as they sink through the magma ocean. Incorporating other elements (e.g. V and Cr) in the model requires, in addition, that the bulk composition of the impactors changes during accretion from reduced (FeO-poor) to oxidised FeO-rich). Then, with the resulting increase in fO2, incomplete reequilibration of the cores during the final 20-30% of Earth accretion is required to satisfy the Ni-Co constraint. In addition, this model enables the concentrations of O and Si in the

  12. Study on the Test Method of Static Earth Pressure Coefficient of Deep Soils

    Institute of Scientific and Technical Information of China (English)

    XU Zhi-wei; ZHOU Guo-qing; LIU Zhi-qiang; ZHAO Xiao-dong; LI Sheng-sheng; ZHANG Lei

    2007-01-01

    The static earth pressure coefficient of soils is, approximately, considered to be a constant in the view of classical soil mechanics. This is supported by many research results. The high pressure experimental research and analysis of remolding deep soil described herein indicate that the static earth pressure of thick overburden has a notable non linear characteristic. It also appears larger than that of superficial soils. It is necessary for deep coal mine design and construction to consider this particularity of soil pressure so as to avoid engineering accidents and heavy loss of life and property.

  13. BALANCE

    Science.gov (United States)

    Carmichael, H.

    1953-01-01

    A torsional-type analytical balance designed to arrive at its equilibrium point more quickly than previous balances is described. In order to prevent external heat sources creating air currents inside the balance casing that would reiard the attainment of equilibrium conditions, a relatively thick casing shaped as an inverted U is placed over the load support arms and the balance beam. This casing is of a metal of good thernnal conductivity characteristics, such as copper or aluminum, in order that heat applied to one portion of the balance is quickly conducted to all other sensitive areas, thus effectively preventing the fornnation of air currents caused by unequal heating of the balance.

  14. Dynamic Active Earth Pressures of the Retaining Piles with Anchors under Vehicle Loads

    OpenAIRE

    Hong-zhi Qiu; Ji-ming Kong; Ren-chao Wang

    2016-01-01

    The pile-anchor supporting structure is widely used in foundation pit engineering; then knowledge of active earth pressure on piles is very important for engineers. In this paper, based on the pseudodynamic method and considering the vehicle’s vibration characteristic, a method to calculate the earth pressure on piles under vehicle load is presented. At the same time, the constraint of anchor is simplified relation of lateral deformation of piles in present method. Effects of a wide range of ...

  15. Comparison of Radiation Pressure Perturbations on Rocket Bodies and Debris at Geosynchronous Earth Orbit

    Science.gov (United States)

    2014-09-01

    1 Comparison of Radiation Pressure Perturbations on Rocket Bodies and Debris at Geosynchronous Earth Orbit Charles J. Wetterer and Keric Hill...and Debris at Geosynchronous Earth Orbit 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK... orbital position arising because of changes in the shape, attitude, angular rates, BRDF parameters, and radiation pressure model are plotted as a

  16. in vivo EFFECTS OF RARE-EARTH BASED NANOPARTICLES ON OXIDATIVE BALANCE IN RATS

    Directory of Open Access Journals (Sweden)

    V. K. Klochkov

    2016-12-01

    Full Text Available The purpose of the research was to find the influence of rare-earth based nanoparticles (CeO2, GdVO2: Eu3+ on the oxidative balance in rats. We analyzed biochemical markers of oxidative stress (lipid peroxidation level, nitric oxide metabolites, sulfhydryl groups content and enzyme activities (superoxide dismutase, catalase in tissues of rats. It has been found that administration of both types of the nanoparticles increased nitric oxide metabolites and products of lipid peroxidation in liver and spleen within 5 days. At injections of GdVO2: Eu3+ lipid peroxidation products, nitric oxide metabolites in serum at 5, 10 and 15 days of the experiment was also increased whereas the level of sulfhydryl groups decreased compared to the intact state and the control. In contrast, under the influence of nanoparticle CeO2 level diene conjugates were not significantly changed and the level of nitric oxide metabolites within 15 day even decreased. During this period, under the influence of both types of nanoparticles the activity of superoxide dismutase was increased, catalase activity was not changed. Oxidative stress coefficient showed the less pronounced CeO2 prooxidant effect (2.04 in comparison to GdVO2: Eu3+ (6.89. However, after-effect of both types of nanoparticles showed complete restoration of oxidative balance values.

  17. Study on the Seismic Active Earth Pressure by Variational Limit Equilibrium Method

    Directory of Open Access Journals (Sweden)

    Jiangong Chen

    2016-01-01

    Full Text Available In the framework of limit equilibrium theory, the isoperimetric model of functional extremum regarding the seismic active earth pressure is deduced according to the variational method. On this basis, Lagrange multipliers are introduced to convert the problem of seismic active earth pressure into the problem on the functional extremum of two undetermined function arguments. Based on the necessary conditions required for the existence of functional extremum, the function of the slip surface and the normal stress distribution on the slip surface is obtained, and the functional extremum problem is further converted into a function optimization problem with two undetermined Lagrange multipliers. The calculated results show that the slip surface is a plane and the seismic active earth pressure is minimal when the action point is at the lower limit position. As the action point moves upward, the slip surface becomes a logarithmic spiral and the corresponding value of seismic active earth pressure increases in a nonlinear manner. And the seismic active earth pressure is maximal at the upper limit position. The interval estimation constructed by the minimum and maximum values of seismic active earth pressure can provide a reference for the aseismic design of gravity retaining walls.

  18. Dynamic Active Earth Pressures of the Retaining Piles with Anchors under Vehicle Loads

    Directory of Open Access Journals (Sweden)

    Hong-zhi Qiu

    2016-01-01

    Full Text Available The pile-anchor supporting structure is widely used in foundation pit engineering; then knowledge of active earth pressure on piles is very important for engineers. In this paper, based on the pseudodynamic method and considering the vehicle’s vibration characteristic, a method to calculate the earth pressure on piles under vehicle load is presented. At the same time, the constraint of anchor is simplified relation of lateral deformation of piles in present method. Effects of a wide range of parameters like rupture angle, vibration acceleration coefficient, wall friction angle, and soil friction angle on active earth pressure have been studied. Results are presented in terms of coefficients in the figures and comparison of the test data and the earth pressure calculated by M-O method and present study. The result shows that the measured earth pressure is accordant with the theoretical analysis, so the method in this paper is an effective basis for the calculation of earth pressure on piles under vehicle loads.

  19. Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

    Institute of Scientific and Technical Information of China (English)

    CAO Wei-dong; DAI Xun; HU Qi-xiang

    2015-01-01

    The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h,H=60 m,n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head (NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model (κ-ε). It is found that axial force of pump with radical reflux balance holes of 5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.

  20. Earth radiation balance as observed and represented in CMIP5 models

    Science.gov (United States)

    Wild, Martin; Folini, Doris; Schär, Christoph; Loeb, Norman; König-Langlo, Gert

    2014-05-01

    The genesis and evolution of Earth's climate is largely regulated by the Earth radiation balance. Despite of its key role in the context of climate change, substantial uncertainties still exist in the quantification of the magnitudes of its different components, and its representation in climate models. While the net radiative energy flows in and out of the climate system at the top of atmosphere are now known with considerable accuracy from new satellite programs such as CERES and SORCE, the energy distribution within the climate system and at the Earth's surface is less well determined. Accordingly, the magnitudes of the components of the surface energy balance have recently been controversially disputed, and potential inconsistencies between the estimated magnitudes of the global energy and water cycle have been emphasized. Here we summarize this discussion as presented in Chapter 2.3 of the 5th IPCC assessment report (AR5). In this context we made an attempt to better constrain the magnitudes of the surface radiative components with largest uncertainties. In addition to satellite observations, we thereby made extensive use of the growing number of surface observations to constrain the radiation balance not only from space, but also from the surface. We combined these observations with the latest modeling efforts performed for AR5 (CMIP5) to infer best estimates for the global mean surface radiative components. Our analyses favor global mean values of downward surface solar and thermal radiation near 185 and 342 Wm-2, respectively, which are most compatible with surface observations (Wild et al. 2013). These estimates are on the order of 10 Wm-2 lower and higher, respectively, than in some of the previous global energy balance assessments, including those presented in previous IPCC reports. It is encouraging that these estimates, which make full use of the information contained in the surface networks, coincide within 2 Wm-2 with the latest satellite

  1. Satellite Earth observation data to identify anthropogenic pressures in selected protected areas

    NARCIS (Netherlands)

    Nagendra, H.; Mairota, P.; Marangi, C.; Lucas, R.; Dimopoulos, P.; Honrado, J.P.; Niphadkara, M.; Mücher, C.A.; Tomaselli, V.; Panitsa, M.; Tarantino, C.; Manakos, I.; Blonda, P.

    2015-01-01

    Protected areas are experiencing increased levels of human pressure. To enable appropriate conservation action, it is critical to map and monitor changes in the type and extent of land cover/use and habitat classes, which can be related to human pressures over time. Satellite Earth observation (EO)

  2. Salt balance: From space experiments to revolutionizing new clinical concepts on earth - A historical review

    Science.gov (United States)

    Gerzer, Rupert

    2014-11-01

    For a long time, sodium balance appeared to be a “done deal” and was thought to be well understood. However, experiments in preparation of space missions showed that the concept of osmotic sodium storage and close correlations of sodium with water balance are only part of the regulatory mechanisms of body salt. By now it has turned out that the human skin is an important storage place and regulator for sodium, that sodium storage involves macrophages which in turn salt-dependently co-regulate blood pressure, that body sodium also strongly influences bone and protein metabolism, and that immune functions are also strongly influenced by sodium. In addition, the aging process appears to lead to increased body sodium storage, which in turn might influence the aging process of the human body. The current review article summarizes the developments that have led to these revolutionizing new findings and concepts as well as consequences deriving from these findings. Therefore, it is not intended in this article to give a complete literature overview over the whole field but to focus on such key literature and considerations that led to the respective developments.

  3. Lateral Earth Pressure behind Walls Rotating about Base considering Arching Effects

    Directory of Open Access Journals (Sweden)

    Dong Li

    2014-01-01

    Full Text Available In field, the earth pressure on a retaining wall is the common effect of kinds of factors. To figure out how key factors act, it has taken into account the arching effects together with the contribution from the mode of displacement of a wall to calculate earth pressure in the proposed method. Based on Mohr circle, a conversion factor is introduced to determine the shear stresses between artificial slices in soil mass. In the light of this basis, a modified differential slices solution is presented for calculation of active earth pressure on a retaining wall. Comparisons show that the result of proposed method is identical to observations from model tests in prediction of lateral pressures for walls rotating about the base.

  4. Three-dimensional axisymmetric magnetosphere in pressure balance with the solar wind

    Science.gov (United States)

    Yates, G. K.; Heinemann, M.

    1986-06-01

    A computer model of a magnetosphere in which the magnetic dipole axis points into the solar wind has been developed. The axial symmetry implied by this physical situation admits a two-dimensional treatment. The model features a magnetopause in pressure balance with the solar wind, an analytic asymptotic tail model to account for the distant magnetotail, and a full accounting of the magnetohydrodynamic pressure in the magnetosphere. The plasma pressure is a function of the Euler potential. The principal physical result is that with an increase in the plasma pressure from zero the magnetic field configuration changes slowly at first. As the pressure increases further, the field configuration changes more rapidly until X and O lines are formed.

  5. The energy balance and pressure in the solar transition zone for network and active region features

    Science.gov (United States)

    Nicolas, K. R.; Bartoe, J.-D. F.; Brueckner, G. E.; Vanhoosier, M. E.

    1979-01-01

    The electron pressure and energy balance in the solar transition zone are determined for about 125 network and active region features on the basis of high spectral and spatial resolution extreme ultraviolet spectra. Si III line intensity ratios obtained from the Naval Research Laboratory high-resolution telescope and spectrograph during a rocket flight are used as diagnostics of electron density and pressure for solar features near 3.5 x 10 to the 4th K. Observed ratios are compared with the calculated dependence of the 1301 A/1312 A and 1301 A/1296 A line intensity ratios on electron density, temperature and pressure. Electron densities ranging from 2 x 10 to the 10th/cu cm to 10 to the 12th/cu cm and active region pressures from 3 x 10 to the 15th to 10 to the 16th/cu cm K are obtained. Energy balance calculations reveal the balance of the divergence of the conductive flux and turbulent energy dissipation by radiative energy losses in a plane-parallel homogeneous transition zone (fill factor of 1), and an energy source requirement for a cylindrical zone geometry (fill factor less than 0.04).

  6. Pressure Dependence of the Charge-Density-Wave Gap in Rare-Earth Tri-Tellurides

    Energy Technology Data Exchange (ETDEWEB)

    Sacchetti, A.; /Zurich, ETH; Arcangeletti, E.; Perucchi, A.; Baldassarre, L.; Postorino, P.; Lupi, S.; /Rome U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.; Degiorgi, L.; /Zurich, ETH

    2009-12-14

    We investigate the pressure dependence of the optical properties of CeTe{sub 3}, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the mid-infrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe{sub 3}.

  7. Earth Pressure at rest of Søvind Marl – a highly overconsolidated Eocene clay

    DEFF Research Database (Denmark)

    Grønbech, Gitte Lyng; Ibsen, Lars Bo; Nielsen, Benjaminn Nordahl

    2016-01-01

    The present study evaluated earth pressure at rest, K0, in highly overconsolidated Eocene clay called Søvind Marl, which exhibits extremely high plasticity indices of up to 300%, a highly fissured structure, and preconsolidation stresses up to 6,800 kPa. Continuous Loading Oedometer (CLO) tests...... in situ stresses to various stress levels to estimate continuous K0 development in this highly overconsolidated clay. The normally consolidated earth pressure at rest was found for two different sample ages of Søvind Marl to be between 0.42 and 0.68. Results indicated the overconsolidated K0 reached...

  8. A novel pneumatic micropipette aspiration method using a balance pressure model

    Science.gov (United States)

    Zhao, Qili; Wu, Ming; Cui, Maosheng; Qin, Yanding; Yu, Jin; Sun, Mingzhu; Zhao, Xin; Feng, Xizeng

    2013-12-01

    This paper presents a novel micropipette aspiration (MA) method based on a common pneumatic micro-injection system. This method is the first to quantify the influence of capillary effect on aspiration pressure using a balance pressure model, and in return, uses the capillary effect to quantify the aspiration pressure. Subsequently, the seal between the cell and the micropipette is detected to judge and exclude the ineffective MA attempts. The rationality of the balance pressure model is validated by the designed micropipette-filling experiments. Through applied to elasticity-determination of the cells with different sizes, the feasibility and versatility of this MA method are proved. With abilities to quantify aspiration pressures and detect the seam between the cell and the micropipette, our method is expected to advance the application of the commercial pneumatic injector in the MA of cells. Moreover, with the quantified volume of the liquid entering into the micropipette during MA process, our method also has a potential applicability to the study of the permeability of the cell membrane in the future.

  9. Seismic earth pressures on flexible cantilever retaining walls with deformable inclusions

    Institute of Scientific and Technical Information of China (English)

    Ozgur L. Ertugrul; Aurelian C. Trandafir

    2014-01-01

    In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wall models retaining composite backfill made of a deformable geofoam inclusion and granular cohesionless material were presented. Two different polystyrene materials were utilized as deformable inclusions. Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wall model were monitored during the tests. The earth pressures and displacements of the retaining walls with deformable inclusions were compared with those of the models without geofoam inclusions. Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall model affect displacement and dynamic lateral pressure profile along the wall height. Depending on the in-clusion characteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures was observed. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wall model increased. On the other hand, dynamic load reduction efficiency of the deformable inclusion increased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility of the deformable layer (the thickness and the elastic stiffness of the polystyrene material) played an important role in the amount of load reduction. Dynamic earth pressure coefficients were compared with those calculated with an analytical approach. Pressure coefficients calculated with this method were found to be in good agreement with the results of the tests performed on the wall model having low flexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at the end of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. The graphs presented within this paper regarding the dynamic earth pressure coefficients versus the wall flexibility and inclusion characteristics may serve for the

  10. Seismic earth pressures on flexible cantilever retaining walls with deformable inclusions

    Directory of Open Access Journals (Sweden)

    Ozgur L. Ertugrul

    2014-10-01

    Full Text Available In this study, the results of 1-g shaking table tests performed on small-scale flexible cantilever wall models retaining composite backfill made of a deformable geofoam inclusion and granular cohesionless material were presented. Two different polystyrene materials were utilized as deformable inclusions. Lateral dynamic earth pressures and wall displacements at different elevations of the retaining wall model were monitored during the tests. The earth pressures and displacements of the retaining walls with deformable inclusions were compared with those of the models without geofoam inclusions. Comparisons indicated that geofoam panels of low stiffness installed against the retaining wall model affect displacement and dynamic lateral pressure profile along the wall height. Depending on the inclusion characteristics and the wall flexibility, up to 50% reduction in dynamic earth pressures was observed. The efficiency of load and displacement reduction decreased as the flexibility ratio of the wall model increased. On the other hand, dynamic load reduction efficiency of the deformable inclusion increased as the amplitude and frequency ratio of the seismic excitation increased. Relative flexibility of the deformable layer (the thickness and the elastic stiffness of the polystyrene material played an important role in the amount of load reduction. Dynamic earth pressure coefficients were compared with those calculated with an analytical approach. Pressure coefficients calculated with this method were found to be in good agreement with the results of the tests performed on the wall model having low flexibility ratio. It was observed that deformable inclusions reduce residual wall stresses observed at the end of seismic excitation thus contributing to the post-earthquake stability of the retaining wall. The graphs presented within this paper regarding the dynamic earth pressure coefficients versus the wall flexibility and inclusion characteristics may

  11. Effect of balanced low pressure drying of curcuma longa leaf on skin immune activation activities.

    Science.gov (United States)

    Choi, Wooseok; Lim, Hye Won; Lee, Hyeon Yong

    2014-01-01

    The effect of balanced low pressure drying pretreatment associated with ultrasonication extraction (BU) on the enhancement of skin immune modulatory activities of Curcuma longa leaf was studied by comparing with conventional hot air drying (HE), freeze drying (FE) and balanced low pressure drying (BE) pretreatment processes. In considering skin immune activation activities such as the inhibition of hyaluronidase activity, the BU extract showed ca. 10% higher than those of HE, and even higher than that of the FE extract. Nitric oxide production from macrophage of the BU extract in adding 1.0 mg/mL was increased up to 16.5 μM. When measuring inhibition of IL-6 and TNF-a production from the human T lymphocytes (T cell), the BU extract also showed 53% and 78% of inhibition effect, respectively. It is found that the BU extract could effectively suppress the expression levels of skin inflammation related genes such as Cox-2 and iNOS, down to 80% and 85% compared to the control, respectively. Balanced low pressure drying process was especially active on dehydration of the leaves with minimizing the destruction and making easier elution of the bioactive substances, which resulted in higher extraction yield and better biological activities.

  12. Solar radiation pressure used for formation flying control around the Sun-Earth libration point

    Institute of Scientific and Technical Information of China (English)

    Sheng-ping GONG; Jun-feng LI; He-xi BAOYIN

    2009-01-01

    Solar radiation pressure is used to control the formation flying around the L2 libration point in the Sun-Earth system. Formation flying control around a halo orbit requires a very small thrust that cannot be satisfied by the latest thrusters. The key contribution of this paper is that the continuous low thrust is produced by solar radiation pressure to achieve the tight formation flying around the libration point. However, only certain families of formation types can be controlled by solar radiation pressure since the direction of solar radiation pressure is restricted to a certain range. Two types of feasible formations using solar radiation pressure control are designed. The conditions of feasible formations are given analytically. Simulations are presented for each case, and the results show that the formations are well controlled by solar radiation pressure.

  13. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    2006-01-01

    The influence of wall flexibility on earth pressure, bending moments and failure modes is studied. Numerical models are compared to results from model tests carried out in a geotechnical centrifuge. The back-fill is dry sand and failure is introduced by allowing the wall to rotate around the anchor...

  14. Physical and numerical modelling of earth pressure on anchored sheet pile walls in sand

    DEFF Research Database (Denmark)

    Krogsbøll, Anette Susanne; Fuglsang, Leif D

    The influence of wall flexibility on earth pressure, bending moments and failure modes is studied. Numerical models are compared to results from model tests carried out in a geotechnical centrifuge. The back-fill is dry sand and failure is introduced by allowing the wall to rotate around the anchor...

  15. Exposure of phototrophs to 548 days in low Earth orbit: microbial selection pressures in outer space and on early earth.

    Science.gov (United States)

    Cockell, Charles S; Rettberg, Petra; Rabbow, Elke; Olsson-Francis, Karen

    2011-10-01

    An epilithic microbial community was launched into low Earth orbit, and exposed to conditions in outer space for 548 days on the European Space Agency EXPOSE-E facility outside the International Space Station. The natural phototroph biofilm was augmented with akinetes of Anabaena cylindrica and vegetative cells of Nostoc commune and Chroococcidiopsis. In space-exposed dark controls, two algae (Chlorella and Rosenvingiella spp.), a cyanobacterium (Gloeocapsa sp.) and two bacteria associated with the natural community survived. Of the augmented organisms, cells of A. cylindrica and Chroococcidiopsis survived, but no cells of N. commune. Only cells of Chroococcidiopsis were cultured from samples exposed to the unattenuated extraterrestrial ultraviolet (UV) spectrum (>110 nm or 200 nm). Raman spectroscopy and bright-field microscopy showed that under these conditions the surface cells were bleached and their carotenoids were destroyed, although cell morphology was preserved. These experiments demonstrate that outer space can act as a selection pressure on the composition of microbial communities. The results obtained from samples exposed to >200 nm UV (simulating the putative worst-case UV exposure on the early Earth) demonstrate the potential for epilithic colonization of land masses during that time, but that UV radiation on anoxic planets can act as a strong selection pressure on surface-dwelling organisms. Finally, these experiments have yielded new phototrophic organisms of potential use in biomass and oxygen production in space exploration.

  16. An Analytical Method for Static Earth Pressure Distribution against Rectangular Shallow Tunnels Using Lateral Deformation

    Directory of Open Access Journals (Sweden)

    Farzad Habibbeygi

    2015-10-01

    Full Text Available Analytical methods for computing the lateral earth pressure against tunnel is vastly used by engineers all over the world. Conventional analytical methods compute the lateral pressure in either active or passive state while the stress state usually falls between these two boundaries in many practical cases. Furthermore, using these boundary coefficients lead to either overestimated or underestimated results in design. Thus, a modified method based on the strain increment theory for calculating the lateral pressure against rectangular tunnels is presented herein to consider the amount of lateral deformation at each depth. First, the results for different values of overburden depth, friction angle and wall mobilized angle are investigated. Then comparative finite element analyses were performed to examine the effectiveness of the method. According to this study, the pressure pattern is completely nonlinear especially at the corners of tunnel lining. In fact, the pressure increases nonlinearly to about three times of the value at top. Lateral earth pressure decreases with the increase of friction angle which is in good agreement with finite element results. Overall, the pressure patterns derived by this method for shallow depths (less than tunnel height are almost the same as those computed by finite element method.

  17. Measuring the initial earth pressure of granite using hydraulic fracturing test; Goseong and Yuseong areas

    Energy Technology Data Exchange (ETDEWEB)

    Park, Byoung Yoon; Bae, Dae Seok; Kim, Chun Soo; Kim, Kyung Su; Koh, Young Kwon; Won, Kyung Sik [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-02-01

    This report provides the initial earth pressure of granitic rocks obtained from Deep Core Drilling Program which is carried out as part of the assessment of deep geological environmental condition. These data are obtained by hydraulic fracturing test in three boreholes drilled up to 350{approx}500 m depth at the Yuseong and Goseong sites. These sites were selected based on the result of preliminary site evaluation study. The boreholes are NX-size (76 mm) and vertical. The procedure of hydraulic fracturing test is as follows: - Selecting the testing positions by preliminary investigation using BHTV logging. - Performing the hydraulic fracturing test at each selected position with depth.- Estimating the shut-in pressure by the bilinear pressure-decay-rate method. - Estimating the fracture reopening pressure from the pressure-time curves.- Estimating the horizontal principal stresses and the direction of principal stresses. 65 refs., 39 figs., 12 tabs. (Author)

  18. Multiscale Pressure-Balanced Structures in Three-Dimensional Magnetohydrodynamic Turbulence

    Science.gov (United States)

    Yang, Liping; He, Jiansen; Tu, Chuanyi; Li, Shengtai; Zhang, Lei; Marsch, Eckart; Wang, Linghua; Wang, Xin; Feng, Xueshang

    2017-02-01

    Observations of solar wind turbulence indicate the existence of multiscale pressure-balanced structures (PBSs) in the solar wind. In this work, we conduct a numerical simulation to investigate multiscale PBSs and in particular their formation in compressive magnetohydrodynamic turbulence. By the use of the higher-order Godunov code Athena, a driven compressible turbulence with an imposed uniform guide field is simulated. The simulation results show that both the magnetic pressure and the thermal pressure exhibit a turbulent spectrum with a Kolmogorov-like power law, and that in many regions of the simulation domain they are anticorrelated. The computed wavelet cross-coherence spectra of the magnetic pressure and the thermal pressure, as well as their space series, indicate the existence of multiscale PBSs, with the small PBSs being embedded in the large ones. These multiscale PBSs are likely to be related to the highly oblique-propagating slow-mode waves, as the traced multiscale PBS is found to be traveling in a certain direction at a speed consistent with that predicted theoretically for a slow-mode wave propagating in the same direction.

  19. Progesterone reduces sympathetic tone without changing blood pressure or fluid balance in men.

    Science.gov (United States)

    Tollan, A; Oian, P; Kjeldsen, S E; Eide, I; Maltau, J M

    1993-01-01

    There is scant information on the effects of progesterone on circulation. Changes in catecholamine levels, blood pressure and transcapillary fluid balance were measured in 12 men before and during administration of natural progesterone (Utrogestan). Before administration, systolic blood pressure was significantly correlated with venous adrenaline (r = 0.67, p = 0.01). There was a significant decrease (p = 0.004) in venous noradrenaline during progesterone administration, and systolic blood pressure was significantly correlated with the arteriovenous difference for noradrenaline (r = 0.66, p = 0.02). Serum progesterone, which attained levels similar to those found in women during the luteal phase, did not significantly alter blood pressure, body weight or intra- to extravascular fluid shift. It is concluded that progesterone may have a direct action by increasing the uptake of noradrenaline from the synaptic cleft or by decreasing the nerve firing rate. Interestingly, the pretreatment finding of a significant correlation between blood pressure and adrenaline was less evident during progesterone administration.

  20. STUDY ON THE OVERALL PRESSURE BALANCE OF A DOWNFLOW CIRCULATING FLUIDIZED BED SYSTEM

    Institute of Scientific and Technical Information of China (English)

    Hengzhi Chen; Dawei Yang; Hongzhong Li; Shiyu Tan

    2006-01-01

    A pressure balance model for a circulating fluidized bed unit that incorporates a downer has been proposed. The model predictions were validated with the experimental data obtained from a special cold-model circulating fluidized bed. Comparison of the operation stability between a CFB downer and a CFB riser has been carried out. Only one critical gas velocity exists in the CFB-riser for a given riser solids flux, while there can be many critical gas velocities for the operation of a CFB downer. Therefore, it is possible to achieve high solids concentration in a CFB downer if appropriate operating conditions are used.

  1. Effects of continuous positive airway pressure on energy balance regulation: a systematic review

    Science.gov (United States)

    Shechter, Ari

    2016-01-01

    Obesity is both a cause and a possible consequence of obstructive sleep apnoea (OSA), as OSA seems to affect parameters involved in energy balance regulation, including food intake, hormonal regulation of hunger/satiety, energy metabolism and physical activity. It is known that weight loss improves OSA, yet it remains unclear why continuous positive airway pressure (CPAP) often results in weight gain. The goal of this systematic review is to explore if and how CPAP affects the behaviour and/or metabolism involved in regulating energy balance. CPAP appears to correct for a hormonal profile characterised by abnormally high leptin and ghrelin levels in OSA, by reducing the circulating levels of each. This is expected to reduce excess food intake. However, reliable measures of food intake are lacking, and not yet sufficient to make conclusions. Although studies are limited and inconsistent, CPAP may alter energy metabolism, with reports of reductions in resting metabolic rate or sleeping metabolic rate. CPAP appears to not have an appreciable effect on altering physical activity levels. More work is needed to characterise how CPAP affects energy balance regulation. It is clear that promoting CPAP in conjunction with other weight loss approaches should be used to encourage optimal outcomes in OSA patients. PMID:27824596

  2. The Balance of Fluid and Osmotic Pressures across Active Biological Membranes with Application to the Corneal Endothelium.

    Directory of Open Access Journals (Sweden)

    Xi Cheng

    Full Text Available The movement of fluid and solutes across biological membranes facilitates the transport of nutrients for living organisms and maintains the fluid and osmotic pressures in biological systems. Understanding the pressure balances across membranes is crucial for studying fluid and electrolyte homeostasis in living systems, and is an area of active research. In this study, a set of enhanced Kedem-Katchalsky (KK equations is proposed to describe fluxes of water and solutes across biological membranes, and is applied to analyze the relationship between fluid and osmotic pressures, accounting for active transport mechanisms that propel substances against their concentration gradients and for fixed charges that alter ionic distributions in separated environments. The equilibrium analysis demonstrates that the proposed theory recovers the Donnan osmotic pressure and can predict the correct fluid pressure difference across membranes, a result which cannot be achieved by existing KK theories due to the neglect of fixed charges. The steady-state analysis on active membranes suggests a new pressure mechanism which balances the fluid pressure together with the osmotic pressure. The source of this pressure arises from active ionic fluxes and from interactions between solvent and solutes in membrane transport. We apply the proposed theory to study the transendothelial fluid pressure in the in vivo cornea, which is a crucial factor maintaining the hydration and transparency of the tissue. The results show the importance of the proposed pressure mechanism in mediating stromal fluid pressure and provide a new interpretation of the pressure modulation mechanism in the in vivo cornea.

  3. Balancing Osmotic Pressure of Electrolytes for Nanoporous Membrane Vanadium Redox Flow Battery with a Draw Solute.

    Science.gov (United States)

    Yan, Ligen; Li, Dan; Li, Shuaiqiang; Xu, Zhi; Dong, Junhang; Jing, Wenheng; Xing, Weihong

    2016-12-28

    Vanadium redox flow batteries with nanoporous membranes (VRFBNM) have been demonstrated to be good energy storage devices. Yet the capacity decay due to permeation of vanadium and water makes their commercialization very difficult. Inspired by the forward osmosis (FO) mechanism, the VRFBNM battery capacity decrease was alleviated by adding a soluble draw solute (e.g., 2-methylimidazole) into the catholyte, which can counterbalance the osmotic pressure between the positive and negative half-cell. No change of the electrolyte volume has been observed after VRFBNM being operated for 55 h, revealing that the permeation of water and vanadium ions was effectively limited. Consequently, the Coulombic efficiency (CE) of nanoporous TiO2 vanadium redox flow battery (VRFB) was enhanced from 93.5% to 95.3%, meanwhile, its capacity decay was significantly suppressed from 60.7% to 27.5% upon the addition of soluble draw solute. Moreover, the energy capacity of the VRFBNM was noticeably improved from 297.0 to 406.4 mAh remarkably. These results indicate balancing the osmotic pressure via the addition of draw solute can restrict pressure-dependent vanadium permeation and it can be established as a promising method for up-scaling VRFBNM application.

  4. Effect of seawater immersion on plasma osmotic pressure and electrolyte balance following open chest trauma

    Institute of Scientific and Technical Information of China (English)

    李辉; 鹿尔驯; 虞积耀; 王大鹏; 马聪

    2002-01-01

    To explore the effect of seawater immersion on serum osmotic pressure and electrolytes balance following chest trauma in dogs. Methods: Twenty-five healthy adult dogs were used in the experiment. A canine model of right open pneumothorax was established by chest puncturing on all animals. Animals were divided into three groups: a control group (n = 10) with chest trauma without any immersion;a seawater group ( n = 10) immersed in seawater after chest trauma and a normal saline group ( n = 5 ) immersed in normal saline solution following chest trauma. Blood samples were taken at different time intervals to determine plasma osmotic pressure and electrolytes. The hemodynamic changes were also recorded. Results: Mortality in the seawater group was much higher than that of the control group and the normal saline group. The mean survival time in the seawater group lasted only 45 minutes, while in the control group and the normal saline group the average survival time was more than 4 hours (P < 0.01 ). One of the most important causes of death was hypernatremia and high osmolality. Severe electrolytes imbalance was observed in seawater group.Hypernatremia and high osmolality were the most significant factors of high mortality in the seawater group. Conclusions: Seawater immersion after chest trauma appears to be associated with severe electrolyte imbalance as well as high osmotic pressure, These may be the risk factors leading to fatal outcome.

  5. High pressure {mu}SR studies: rare earths and related materials

    Energy Technology Data Exchange (ETDEWEB)

    Kalvius, G.M., E-mail: kalvius@ph.tum.de; Schreier, E. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ekstroem, M.; Hartmann, O. [Uppsala University, Physics Department (Sweden); Henneberger, S., E-mail: kalvius@ph.tum.de; Kratzer, A. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Waeppling, R. [Uppsala University, Physics Department (Sweden); Martin, E., E-mail: kalvius@ph.tum.de; Burghart, F.J. [Technical University Munich, Physics Department (Germany)], E-mail: kalvius@ph.tum.de; Ballou, R.; Deportes, J. [CNRS, Laboratoire Louis Neel (France); Niedermayer, Ch. [University of Constance, Faculty of Physics (Germany)

    2000-11-15

    After a short introduction to {mu}SR with respect to the study of magnetic properties, followed by a brief outline of the principle of the high pressure-low temperature {mu}SR spectrometer installed at the Paul Scherrer Institute, we discuss some measurements on rare earth materials employing this instrument. They are concerned with: (1) The pressure dependence of the spin turning process in ferromagnetic Gd. (2) The volume dependence of the internal magnetic field in the heavy rare earth metals Gd, Dy, and Ho in their ordered magnetic states. (3) The response of the (first order) magnetic transition in the frustrated antiferromagnets of type RMn{sub 2} (R = Y,Gd) to pressure. (4) The variation of magnetic parameters with pressure in La{sub 2}CuO{sub 4} (powder sample), the antiferromagnetic parent compound of the high T{sub C} superconductors of type La{sub 2-x}(Sr, Ba){sub x}CuO{sub 4}. In conclusion a short outlook on further developments is given.

  6. Magnetic ordering temperatures in rare earth metal dysprosium under ultrahigh pressures

    Science.gov (United States)

    Samudrala, Gopi K.; Tsoi, Georgiy M.; Weir, Samuel T.; Vohra, Yogesh K.

    2014-04-01

    Magnetic ordering temperatures in heavy rare earth metal dysprosium (Dy) have been studied using an ultrasensitive electrical transport measurement technique in a designer diamond anvil cell to a pressure of 69 GPa and a temperature of 10 K. Previous studies using magnetic susceptibility measurements at high pressures were able to track magnetic ordering temperature only till 7 GPa in the hexagonal close packed (hcp) phase of Dy. Our studies indicate that the magnetic ordering temperature shows an abrupt drop of 80 K at the hcp-Sm phase transition followed by a gradual decrease that continues till 17 GPa. This is followed by a rapid increase in the magnetic ordering temperatures in the double hcp phase and finally leveling off in the distorted face centered cubic phase of Dy. Our studies reaffirm that 4f-shell remains localized in Dy and there is no loss of magnetic moment or 4f-shell delocalization for pressures up to 69 GPa.

  7. Effects of Amazonian Dark Earths on growth and leaf nutrient balance of tropical tree seedlings

    NARCIS (Netherlands)

    Quintero Vallejo, Estela; Pena Claros, M.; Bongers, F.; Toledo, M.; Poorter, L.

    2015-01-01

    Background and aims: Amazonian Dark Earths (ADE) are ancient anthropogenic soils distributed in the Amazon basin. They are characterized by high nutrients such as phosphorus, calcium, potassium and nitrogen. We studied the effect of ADE on growth, morphology and physiology of 17 tree species from a

  8. THE INFLUENCE OF PRESSURE-DEPENDENT VISCOSITY ON THE THERMAL EVOLUTION OF SUPER-EARTHS

    Energy Technology Data Exchange (ETDEWEB)

    Stamenkovic, Vlada; Noack, Lena; Spohn, Tilman [Institute of Planetology, Westfaelische Wilhelms-Universitaet Muenster, Wilhelm-Klemm-Str. 10, 48149 Muenster (Germany); Breuer, Doris, E-mail: Vlada.Stamenkovic@dlr.de, E-mail: Lena.Noack@dlr.de, E-mail: Doris.Breuer@dlr.de, E-mail: Tilman.Spohn@dlr.de [Institute of Planetary Research, German Aerospace Center DLR, Rutherfordstrasse 2, 12489 Berlin (Germany)

    2012-03-20

    We study the thermal evolution of super-Earths with a one-dimensional (1D) parameterized convection model that has been adopted to account for a strong pressure dependence of the viscosity. A comparison with a 2D spherical convection model shows that the derived parameterization satisfactorily represents the main characteristics of the thermal evolution of massive rocky planets. We find that the pressure dependence of the viscosity strongly influences the thermal evolution of super-Earths-resulting in a highly sluggish convection regime in the lower mantles of those planets. Depending on the effective activation volume and for cooler initial conditions, we observe with growing planetary mass even the formation of a conductive lid above the core-mantle boundary (CMB), a so-called CMB-lid. For initially molten planets our results suggest no CMB-lids but instead a hot lower mantle and core as well as sluggish lower mantle convection. This implies that the initial interior temperatures, especially in the lower mantle, become crucial for the thermal evolution-the thermostat effect suggested to regulate the interior temperatures in terrestrial planets does not work for massive planets if the viscosity is strongly pressure dependent. The sluggish convection and the potential formation of the CMB-lid reduce the convective vigor throughout the mantle, thereby affecting convective stresses, lithospheric thicknesses, and heat fluxes. The pressure dependence of the viscosity may therefore also strongly affect the propensity of plate tectonics, volcanic activity, and the generation of a magnetic field of super-Earths.

  9. Novel Techniques for High Pressure Falling Sphere Viscosimetry under Simulated Earth's Mantle Conditions

    Science.gov (United States)

    Mueller, H. J.; Beckmann, F.; Dobson, D. P.; Hunt, S. A.; Secco, R.; Lauterjung, J.; Lathe, C.

    2014-12-01

    Viscosity data of melts measured under in situ high pressure conditions are crucial for the understanding of Earth's lower mantle and the interior of terrestrial and extrasolar Super-Earth planets. We report recent technical advances and techniques enabling falling sphere viscosity measurements in single- and double-stage DIA-type multi-anvil apparatus. For the experiments we used presses with a maximum load of 250 tons and 1750 tons. We anticipate that our system will enable viscosity measurements up to the maximum pressure for non-diamond anvils, i.e. pressures up to some 30 GPa. For the development of the new set ups the deformation of the cell assemblies were analyzed by X-ray absorption tomography at beamline W II at DESY/HASYLAB after the high pressure runs. These analysis gave considerable insights into strategies for improving the cell assembly with the result that the optimized assemblies could be used at much higher pressures without blow-outs. We think this approach is much faster and more beneficial than the classical way of trial and error. Additionally to prevent high pressure blow outs the task was to make the whole melting chamber accessible for the high pressure X-radiography system up to the maximum pressures. This way the accuracy and reliability of the measurements can be improved. For this goal we used X-ray transparent cBN-anvils at the single-stage DIA large volume press. Because this material is recently not available for the cube size of 32 mm this aproach did not work for the double-stage DIA. As a very useful and economical alternative we used slotted carbide anvils filled with fired pyrophyllite bars. To improve the frame quality of the platinum spheres taken by the CCD-camera the energy of the monochromatic X-rays had to be increased to 100 keV. The resulting ascent of scattered radiation required a new design of the X-radiography unit. Our results are demonstrated with viscosity measurements following Stokes law by evaluation of X

  10. A Plantar-pressure Based Tongue-placed Tactile Biofeedback System for Balance Improvement

    CERN Document Server

    Vuillerme, Nicolas; Pinsault, Nicolas; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

    2007-01-01

    Maintaining an upright stance represents a complex task, which is achieved by integrating sensory information from the visual, vestibular and somatosensory systems. When one of these sensory inputs becomes unavailable and/or inaccurate and/or unreliable, postural control generally is degraded. One way to solve this problem is to supplement and/or substitute limited/altered/missing sensory information by providing additional sensory information to the central nervous system via an alternative sensory modality. Along these lines, we developed an original biofeedback system [1] whose underlying principle consists in supplying the user with supplementary sensory information related to foot sole pressure distribution through a tongue-placed output device (Tongue Display Unit, "TDU" [2]). The purpose of the present experiment was to assess its effectiveness in improving balance in young healthy adults.

  11. Neutral gas density depletion due to neutral gas heating and pressure balance in an inductively coupled plasma

    Science.gov (United States)

    Shimada, Masashi; Tynan, George R.; Cattolica, Robert

    2007-02-01

    The spatial distribution of neutral gas temperature and total pressure have been measured for pure N2, He/5%N2 and Ar/5%N2 in an inductively coupled plasma (ICP) reactor, and a significant rise in the neutral gas temperature has been observed. When thermal transpiration is used to correct total pressure measurements, the total pressure remains constant regardless of the plasma condition. Neutral pressure is depleted due to the pressure balance when the plasma pressure (mainly electron pressure) becomes comparable to the neutral pressure in high density plasma. Since the neutral gas follows the ideal gas law, the neutral gas density profile was obtained from the neutral gas temperature and the corrected neutral pressure measurements. The results show that the neutral gas density at the centre of the plasma chamber (factor of 2-4 ×) decreases significantly in the presence of a plasma discharge. Significant spatial variation in neutral gas uniformity occurs in such plasmas due to neutral gas heating and pressure balance.

  12. Evolution of the Oxidation State of the Earth's Mantle: Challenges of High Pressure Quenching

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L.; Christoffersen, R.; Rahman, Z.

    2015-01-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion, transitioned from reduced to oxidized, or from oxidized to reduced. We investigate the stability of Fe3+ at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. Experiments of more mafic compositions and at higher pressures commonly form a polyphase quench intergrowth composed primarily of pyroxenes, with interstitial glass which hosts nearly all of the more volatile minor elements. In our previous experiments on shergottite compositions, variable fO2, T, and P is less than 4 GPa, Fe3+/TotFe decreased slightly with increasing P, similar to terrestrial basalt. For oxidizing experiments less than 7GPa, Fe3+/TotFe decreased as well, but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3+. Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Experiments with Knippa basalt as the starting composition were conducted at 1-8 GPa and 1800 C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products from 7-8 GPa quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal Fe3+/2+. A number of different approaches have been employed to produce glassy samples that can be measured by EELS and XANES. A more intermediate andesite was used in one experiment, and decompression during quenching was attempted after, but both resulted in a finer grained polyphase texture. Experiments are currently underway to test different capsule materials may affect quench texture. A preliminary experiment using liquid nitrogen to greatly enhance the rate of cooling of the assembly has also been attempted and this technique will be

  13. Implications for Core Formation of the Earth from High Pressure-Temperature Au Partitioning Experiments

    Science.gov (United States)

    Danielson, L. R.; Sharp, T. G.; Hervig, R. L.

    2005-01-01

    Siderophile elements in the Earth.s mantle are depleted relative to chondrites. This is most pronounced for the highly siderophile elements (HSEs), which are approximately 400x lower than chondrites. Also remarkable is the relative chondritic abundances of the HSEs. This signature has been interpreted as representing their sequestration into an iron-rich core during the separation of metal from silicate liquids early in the Earth's history, followed by a late addition of chondritic material. Alternative efforts to explain this trace element signature have centered on element partitioning experiments at varying pressures, temperatures, and compositions (P-T-X). However, first results from experiments conducted at 1 bar did not match the observed mantle abundances, which motivated the model described above, a "late veneer" of chondritic material deposited on the earth and mixed into the upper mantle. Alternatively, the mantle trace element signature could be the result of equilibrium partitioning between metal and silicate in the deep mantle, under P-T-X conditions which are not yet completely identified. An earlier model determined that equilibrium between metal and silicate liquids could occur at a depth of approximately 700 km, 27(plus or minus 6) GPa and approximately 2000 (plus or minus 200) C, based on an extrapolation of partitioning data for a variety of moderately siderophile elements obtained at lower pressures and temperatures. Based on Ni-Co partitioning, the magma ocean may have been as deep as 1450 km. At present, only a small range of possible P-T-X trace element partitioning conditions has been explored, necessitating large extrapolations from experimental to mantle conditions for tests of equilibrium models. Our primary objective was to reduce or remove the additional uncertainty introduced by extrapolation by testing the equilibrium core formation hypothesis at P-T-X conditions appropriate to the mantle.

  14. High-pressure phase of brucite stable at Earth's mantle transition zone and lower mantle conditions

    Science.gov (United States)

    Hermann, Andreas; Mookherjee, Mainak

    2016-12-01

    We investigate the high-pressure phase diagram of the hydrous mineral brucite, Mg(OH)2, using structure search algorithms and ab initio simulations. We predict a high-pressure phase stable at pressure and temperature conditions found in cold subducting slabs in Earth’s mantle transition zone and lower mantle. This prediction implies that brucite can play a much more important role in water transport and storage in Earth’s interior than hitherto thought. The predicted high-pressure phase, stable in calculations between 20 and 35 GPa and up to 800 K, features MgO6 octahedral units arranged in the anatase–TiO2 structure. Our findings suggest that brucite will transform from a layered to a compact 3D network structure before eventual decomposition into periclase and ice. We show that the high-pressure phase has unique spectroscopic fingerprints that should allow for straightforward detection in experiments. The phase also has distinct elastic properties that might make its direct detection in the deep Earth possible with geophysical methods.

  15. Correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi Chuan.

    Science.gov (United States)

    Gatica-Rojas, Valeska; Cartes-Velásquez, Ricardo; Salgado-Méndez, Rodrigo; Castro-Ramírez, Rodolfo

    2016-08-01

    [Purpose] This study aimed to determine the correlation between center of pressure and functional balance in non-faller elderly practitioners of Tai Chi. [Subjects and Methods] For the study, nine non-faller elderly practitioners of Tai Chi who were able to maintain a standing posture and walk independently were recruited. Timed one-leg standing and timed up-and-go tests were used as functional balance tests and force platform to measure the center of pressure. The Pearson correlation coefficient was calculated for the timed up-and-go/timed one-leg standing test scores and center of pressure parameter values. [Results] None of the correlations was statistically significant, but moderate correlations were observed between the pairs timed one-leg standing/sway area of center of pressure, timed one-leg standing/standard deviation of center of pressure in the mediolateral direction, timed one-leg standing/mean velocity of center of pressure in the anteroposterior direction, and timed up-and-go test sway area of center of pressure. [Conclusion] Timed one-leg standing is more appropriate than timed up-and-go test for the measurement of functional balance in non-faller elderly practitioners of Tai Chi.

  16. Lateral Earth Pressure at Rest and Shear Modulus Measurements on Hanford Sludge Simulants

    Energy Technology Data Exchange (ETDEWEB)

    Wells, Beric E.; Jenks, Jeromy WJ; Boeringa, Gregory K.; Bauman, Nathan N.; Guzman, Anthony D.; Arduino, P.; Keller, P. J.

    2010-09-30

    This report describes the equipment, techniques, and results of lateral earth pressure at rest and shear modulus measurements on kaolin clay as well as two chemical sludge simulants. The testing was performed in support of the problem of hydrogen gas retention and release encountered in the double- shell tanks (DSTs) at the Hanford Site near Richland, Washington. Wastes from single-shell tanks (SSTs) are being transferred to double-shell tanks (DSTs) for safety reasons (some SSTs are leaking or are in danger of leaking), but the available DST space is limited.

  17. Lifshitz and other transitions in alkaline-earth 122 pnictides under pressure

    Science.gov (United States)

    Quader, Khandker; Widom, Michael

    2014-10-01

    We carry out T =0 first-principles total energy calculations in the entire set of alkaline 122-pnictides (A Fe2As2 ; A = alkaline-earth element Ca, Sr, Ba, Ra) as a function of hydrostatic pressure. We find multiple distinct transitions to occur, namely an enthalpic transition in which the zero-pressure striped antiferromagnetic orthorhombic (OR-AFM) phase becomes thermodynamically less stable than a competing tetragonal (T) phase, a magnetic transition in which the OR-AFM phase loses its magnetism and orthorhombicity, and a lattice parameter anomaly in which the tetragonal c-axis collapses and a collapsed tetragonal (cT) phase becomes stable. Our results for energy band dispersions and spectra, lattice parameters, enthalpies, magnetism, and elastic constants over a wide range of hydrostatic pressure provide a coherent understanding of these experimentally observed transitions. In particular, the T-cT transition and anomalies in lattice parameters and elastic properties, observed at finite temperatures, are interpreted as arising from proximity to T =0 Lifshitz transitions, wherein pressure causes nontrivial changes in the Fermi surface topology in these materials.

  18. Earth

    CERN Document Server

    Carter, Jason

    2017-01-01

    This curriculum-based, easy-to-follow book teaches young readers about Earth as one of the eight planets in our solar system in astronomical terms. With accessible text, it provides the fundamental information any student needs to begin their studies in astronomy, such as how Earth spins and revolves around the Sun, why it's uniquely suitable for life, its physical features, atmosphere, biosphere, moon, its past, future, and more. To enhance the learning experience, many of the images come directly from NASA. This straightforward title offers the fundamental information any student needs to sp

  19. Evolution of the Oxidation State of the Earth's Mantle: Challenges of High Pressure Quenching

    Science.gov (United States)

    Danielson, L. R.; Righter, K.; Keller, L. P.; Rahman, Z.

    2015-12-01

    The oxidation state of the Earth's mantle during formation remains an unresolved question, whether it was constant throughout planetary accretion [1], transitioned from reduced to oxidized [2,3,4], or from oxidized to reduced [1,5]. We investigate the stability of Fe3+ at depth, in order to constrain processes (water, late accretion, dissociation of FeO) which may reduce or oxidize the Earth's mantle. Experiments of more mafic compositions and at higher pressures commonly form a polyphase quench intergrowth composed primarily of pyroxenes, with interstitial glass which hosts nearly all of the more volatile minor elements. In our previous experiments on shergottite compositions, variable fO2, T, and P <4 GPa, Fe3+/ΣFe decreased slightly with increasing P, similar to terrestrial basalt [6,7,8]. For oxidizing experiments < 7GPa, Fe3+/ΣFe decreased as well [9], but it's unclear from previous modelling whether the deeper mantle could retain significant Fe3+ [1,10]. Our current experiments expand our pressure range deeper into the Earth's mantle and focus on compositions and conditions relevant to the early Earth. Experiments with Knippa basalt as the starting composition were conducted at 1-8 GPa and 1800 °C, using a molybdenum capsule to set the fO2 near IW, by buffering with Mo-MoO3. TEM and EELS analyses revealed the run products from 7-8 GPa quenched to polycrystalline phases, with the major phase pyroxene containing approximately equal Fe3+/2+. A number of different approaches have been employed to produce glassy samples that can be measured by EELS and XANES. A more intermediate andesite was used in one experiment, and decompression during quenching was attempted after [11], but both resulted in a finer grained polyphase texture. Experiments are currently underway to test how different capsule materials may affect quench texture. A preliminary experiment using liquid nitrogen to greatly enhance the rate of cooling of the assembly has also been attempted and

  20. Simplification of heating systems by omitting circulating pumps and differential pressure regulating valves. Balancing; Vereinfachung durch Einsparung von Umwaelzpumpen und Differenzdruckregler. Hydraulischer Abgleich

    Energy Technology Data Exchange (ETDEWEB)

    Gebauer, Marc [Baelz W. und Sohn GmbH und Co., Berlin (Germany)

    2011-07-01

    Balancing of heating systems today is possible without differential pressure regulating valves. Only the design basis volume flow is adjusted at the sectioning valve of the heating section, while the part-load behaviour is regulated accurately via thermal power regulation. This simplifies balancing, and the total efficiency of systems will be better than with the commonly used differential pressure regulating valves.

  1. Axisymmetric drop shape analysis-constrained sessile drop (ADSA-CSD): a film balance technique for high collapse pressures.

    Science.gov (United States)

    Saad, Sameh M I; Policova, Zdenka; Acosta, Edgar J; Neumann, A Wilhelm

    2008-10-07

    Collapse pressure of insoluble monolayers is a property determined from surface pressure/area isotherms. Such isotherms are commonly measured by a Langmuir film balance or a drop shape technique using a pendant drop constellation (ADSA-PD). Here, a different embodiment of a drop shape analysis, called axisymmetric drop shape analysis-constrained sessile drop (ADSA-CSD) is used as a film balance. It is shown that ADSA-CSD has certain advantages over conventional methods. The ability to measure very low surface tension values (e.g., drop setup, and leak-proof design make the constrained sessile drop constellation a better choice than the pendant drop constellation in many situations. Results of compression isotherms are obtained on three different monolayers: octadecanol, dipalmitoyl-phosphatidyl-choline (DPPC), and dipalmitoyl-phosphatidyl-glycerol (DPPG). The collapse pressures are found to be reproducible and in agreement with previous methods. For example, the collapse pressure of DPPC is found to be 70.2 mJ/m2. Such values are not achievable with a pendant drop. The collapse pressure of octadecanol is found to be 61.3 mJ/m2, while that of DPPG is 59.0 mJ/m2. The physical reasons for these differences are discussed. The results also show a distinctive difference between the onset of collapse and the ultimate collapse pressure (ultimate strength) of these films. ADSA-CSD allows detailed study of this collapse region.

  2. Quantification and reliability of center of pressure movement during balance tasks of varying difficulty.

    Science.gov (United States)

    Baltich, Jennifer; von Tscharner, Vinzenz; Zandiyeh, Payam; Nigg, Benno M

    2014-06-01

    Postural control is often assessed by quantifying the magnitude of the center of pressure (COP) movement. However, these measures usually focus on the gross amount of movement and ignore the temporal structure of the COP signal. A novel non-linear analysis technique was recently developed to characterize the temporal structure of the COP signal with an output termed the entropic half-life [E(1/2)]. The E(1/2) reflects how much of the previous postural position is used to determine the current postural control strategy (memory effect). The purpose of this study was to quantify the E(1/2) and four COP movement magnitude measurements (medio-lateral and anterior-posterior excursion, path length, 95% ellipse area) for balance tasks increasing in sensory difficulty, as well as the test-retest reliability of each measure. Twenty-seven healthy young adults completed single limb stance tasks varying in sensory difficulty (rigid surface eyes open, rigid surface eyes closed, foam surface eyes open) on two separate occasions. Relative reliability was assessed using an intraclass correlation coefficient (ICC3,3). Absolute reliability was assessed using the standard error of the measurement (SEM) and the sensitivity of the measurement to true changes was assessed using the minimal detectable change (MDC95). The E(1/2) was found to have excellent reliability for all tasks tested (ICC range 0.82-0.91, SEM range 3.5-14.1 mm, MCD95 range 9.7-39.2 mm). The high reliability of the E(1/2) was comparable to that of movement magnitude measurements. This may be used in order to better understand the underlying motor control system.

  3. Differential Velocity between Solar Wind Protons and Alpha Particles in Pressure Balance Structures

    Science.gov (United States)

    Yamauchi, Yohei; Suess, Steven T.; Steinberg, John T.; Sakurai, Takashi

    2004-01-01

    Pressure balance structures (PBSs) are a common high-plasma beta feature in high-latitude, high-speed solar wind. They have been proposed as remnants of coronal plumes. If true, they should reflect the observation that plumes are rooted in unipolar magnetic flux concentrations in the photosphere and are heated as oppositely directed flux is advected into and reconnects with the flux concentration. A minimum variance analysis (MVA) of magnetic discontinuities in PBSs showed there is a larger proportion of tangential discontinuities than in the surrounding high-speed wind, supporting the hypothesis that plasmoids or extended current sheets are formed during reconnection at the base of plumes. To further evaluate the character of magnetic field discontinuities in PBSs, differential streaming between alpha particles and protons is analyzed here for the same sample of PBSs used in the MVA. Alpha particles in high-speed wind generally have a higher radial flow speed than protons. However, if the magnetic field is folded back on itself, as in a large-amplitude Alfven wave, alpha particles will locally have a radial flow speed less than protons. This characteristic is used here to distinguish between folded back magnetic fields (which would contain rotational discontinuities) and tangential discontinuities using Ulysses high-latitude, high-speed solar wind data. The analysis indicates that almost all reversals in the radial magnetic field in PBSs are folded back field lines. This is found to also be true outside PBSs, supporting existing results for typical high-speed, high-latitude wind. There remains a small number of cases that appear not to be folds in the magnetic field and which may be flux tubes with both ends rooted in the Sun. The distinct difference in MVA results inside and outside PBSs remains unexplained.

  4. MEMS Technology Sensors as a More Advantageous Technique for Measuring Foot Plantar Pressure and Balance in Humans

    Directory of Open Access Journals (Sweden)

    Clara Sanz Morère

    2016-01-01

    Full Text Available Locomotor activities are part and parcel of daily human life. During walking or running, feet are subjected to high plantar pressure, leading sometimes to limb problems, pain, or foot ulceration. A current objective in foot plantar pressure measurements is developing sensors that are small in size, lightweight, and energy efficient, while enabling high mobility, particularly for wearable applications. Moreover, improvements in spatial resolution, accuracy, and sensitivity are of interest. Sensors with improved sensing techniques can be applied to a variety of research problems: diagnosing limb problems, footwear design, or injury prevention. This paper reviews commercially available sensors used in foot plantar pressure measurements and proposes the utilization of pressure sensors based on the MEMS (microelectromechanical systems technique. Pressure sensors based on this technique have the capacity to measure pressure with high accuracy and linearity up to high pressure levels. Moreover, being small in size, they are highly suitable for this type of measurement. We present two MEMS sensor models and study their suitability for the intended purpose by performing several experiments. Preliminary results indicate that the sensors are indeed suitable for measuring foot plantar pressure. Importantly, by measuring pressure continuously, they can also be utilized for body balance measurements.

  5. Three-dimensional numerical simulation and earth pressure analysis on double-row piles with consideration of spatial effects

    Institute of Scientific and Technical Information of China (English)

    Zi-han WANG; Jian ZHOU

    2011-01-01

    As a new kind of technology in retaining structures,the characteristics of double-row piles are significantly affected by spatial effects.In this paper,double-row piles as a retaining structure are simulated numerically in three-dimension by finite element software PLAXIS 3D FOUNDATION.The behavior differences of piles in different positions around the foundation pit are analyzed.By changing the parameters,including the length-width ratio,the excavation depth,the distance between rows and the diameter of piles,the variations of the lateral deformation,the bending moment and the earth pressure around the piles are determined.The reasonable values of parameters and some suggestions with consideration of earth pressure are proposed for the design of double-row piles as a retaining structure.The results show that the lateral deformation and bending moment are the largest in the middle of long side of the foundation pit,which is identified as the most unfavorable position.It is indicated that the earth pressure between rows above pit bottom is close to active earth pressure,while the earth pressure between rows under pit bottom is close to static earth pressure.It is suggested that 1/2-2/3 of pile length,0.6-1.2 m,3d-6d,and 2d-2.5d be chosen as embedded depth of piles,diameter of piles,distance between rows,and distance between piles,respectively,where d is the pile diameter.

  6. Present-day and future Antarctic ice sheet climate and surface mass balance in the Community Earth System Model

    Science.gov (United States)

    Lenaerts, Jan T. M.; Vizcaino, Miren; Fyke, Jeremy; van Kampenhout, Leo; van den Broeke, Michiel R.

    2016-09-01

    We present climate and surface mass balance (SMB) of the Antarctic ice sheet (AIS) as simulated by the global, coupled ocean-atmosphere-land Community Earth System Model (CESM) with a horizontal resolution of {˜ }1° in the past, present and future (1850-2100). CESM correctly simulates present-day Antarctic sea ice extent, large-scale atmospheric circulation and near-surface climate, but fails to simulate the recent expansion of Antarctic sea ice. The present-day Antarctic ice sheet SMB equals 2280 ± 131 {Gt year^{-1}}, which concurs with existing independent estimates of AIS SMB. When forced by two CMIP5 climate change scenarios (high mitigation scenario RCP2.6 and high-emission scenario RCP8.5), CESM projects an increase of Antarctic ice sheet SMB of about 70 {Gt year^{-1}} per degree warming. This increase is driven by enhanced snowfall, which is partially counteracted by more surface melt and runoff along the ice sheet's edges. This intensifying hydrological cycle is predominantly driven by atmospheric warming, which increases (1) the moisture-carrying capacity of the atmosphere, (2) oceanic source region evaporation, and (3) summer AIS cloud liquid water content.

  7. Method for achieving hydraulic balance in typical Chinese building heating systems by managing differential pressure and flow

    DEFF Research Database (Denmark)

    Zhang, Lipeng; Xia, Jianjun; Thorsen, Jan Eric;

    2017-01-01

    Hydraulic unbalance is a common problem in Chinese district heating (DH) systems. Hydraulic unbalance has resulted in poor flow distribution among heating branches and overheating of apartments. Studies show that nearly 30% of the total heat supply is being wasted in Chinese DH systems due...... to a lack of pressure and flow control. This study investigated using pre-set radiator valves combined with differential pressure (DP) controllers to achieve hydraulic balance in building distribution systems, and consequently save energy and reduce the emissions. We considered a multi-storey building...

  8. Unusual pressure dependence of the crystallographic structure in RNiO{sub 3} perovskites (R = rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Medarde, M.; Mesot, J.; Rosenkranz, S. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Lacorre, P. [Lab. Fluorures, Le Mans (France); Marshall, W.; Loveday, J.S. [Edinburgh Univ. (United Kingdom); Klotz, S.; Hamel, G. [Paris-6 Univ., 75 (France)

    1997-09-01

    We report the first experimental observation of a pressure-induced structural phase transition in the RNiO{sub 3} series (R = rare earth). At {approx_equal} 40 kbar, the space group of NdNiO{sub 3} changes from Pbnm(orthorhombic) to the PrNiO{sub 3} indicating that the symmetry of the structure increases with pressure. (author) 1 fig., 7 refs.

  9. Study on passive earth pressure acting on the embedment of an earth retaining wall for braced excavation work in cohesive soil; Nenseido jiban ni okeru kussaku dodomeheki neirebu no judo doatsu ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, H. [Pacific Consultants K.K., Tokyo (Japan); Hirashima, K. [Yamanashi University, Yamanashi (Japan). Faculty of Engineering

    1995-12-15

    Passive earth pressure exerts a great influence on the stress and deformation of earth retaining walls in braced excavation. To calculate this pressure, conventional ultimate earth pressure equation, or Rankine-Resals and Coulomb`s equation, are currently applied respectively to cohesive and sandy soil. However, these intentional equation to determine passive earth pressure do not adequately take into account the excavation width during work and the shearing resistance on the earth retaining wall surface. This paper deals with cohesive soil only, deriving a calculation equation for passive earth pressure, which takes into account excavation width and the shearing resistance of the earth retaining wall surface. Then, constants in this equation are determined using the calculation results obtained from the finite element method with blasts-plastic elements. The calculation results are also compared with measured values in the model test in order to check the applicability of the calculation equation for passive earth pressure thus obtained. Finally, this paper proposes a practicable calculation equation for passive earth pressure. 13 refs., 10 figs., 10 tabs.

  10. Pickup protons and pressure-balanced structures from 39 to 43 AU: Voyager 2 observations during 1993 and 1994

    Science.gov (United States)

    Burlaga, L. F.; Ness, N. F.; Belcher, J. W.; Whang, Y. C.

    1996-07-01

    The pressure of interstellar pickup protons in the distant heliosphere can be determined by analyzing pressure-balanced structures, observed on a scale of a few hundredths of an AU. This paper extends the earlier work of L. F. Burlaga et al. (Journal of Geophysical Research, 99, 21, 511, 1994) by analyzing pressure-balanced structures observed by Voyager 2 from 39.3 to 40.6 AU in 1993 and from 42.6 to 43.2 AU during 1994. The pickup proton temperature is high in the region of the distant heliosphere that we considered: (5.4+/-0.1)×106 K at 39-41 AU and (6.0+/-0.4)×106 K at ~43 AU. The density of the pickup protons is (1.6+/-0.3)×10-4 cm-3 at 39-41 AU and (1.2+/-0.2)×10-4 cm-3 at ~43 AU. The ratio of the pickup proton density to the solar wind proton density (Ni/N) is small, only 0.03+/-0.01 during both 1993 and 1994. Nevertheless, the pickup proton pressures are relatively high because of their high temperatures. The pickup proton pressure was (11+/-2)×10-14 ergcm-3 at 39-41 AU and (9+/-1)×10-14 ergcm-3 at 43 AU. There is a possible decrease in Pi with increasing distance from the Sun. The pickup proton pressure is an order of magnitude greater than the solar wind proton pressure: Pi/Pswp=10+/-2 at 39-41 AU and 8+/-2 at 43 AU. Our results support the hypothesis of Burlaga et al. that the pickup proton pressure is more important than the solar wind thermal pressure in the dynamics of the distant heliosphere. The ratio of the pickup ion pressure to the magnetic pressure is Pi/(B2/8π)=1.7+/-0.3 at 39-41 AU and 1.7+/-0.72 at ~43 AU. These results are compared with a model.

  11. 力平衡法测量大气压强%Atmospheric pressure measurement based on force balance principle

    Institute of Scientific and Technical Information of China (English)

    钟寿仙; 杨自强; 任团结; 夏亚康; 胡家晨; 林春丹

    2014-01-01

    依据力平衡法原理,重新构思、设计了测量大气压强的实验方案及装置,力学传感器的使用,提高了大气压强测量中的关键物理量的测量精度;采用最小二乘法,实现了大气压强的巧妙测量。%Based on the force balance principle ,the experimental scheme and apparatus were rede-signed to measure the atmospheric pressure .By using mechanical sensor and least square method ,the atmospheric pressure had been measured ingeniously ,and the measurement accuracies of atmospheric pressure and the relevant key physical quantities were improved .

  12. Discovery of earth-abundant nitride semiconductors by computational screening and high-pressure synthesis

    Science.gov (United States)

    Hinuma, Yoyo; Hatakeyama, Taisuke; Kumagai, Yu; Burton, Lee A.; Sato, Hikaru; Muraba, Yoshinori; Iimura, Soshi; Hiramatsu, Hidenori; Tanaka, Isao; Hosono, Hideo; Oba, Fumiyasu

    2016-01-01

    Nitride semiconductors are attractive because they can be environmentally benign, comprised of abundant elements and possess favourable electronic properties. However, those currently commercialized are mostly limited to gallium nitride and its alloys, despite the rich composition space of nitrides. Here we report the screening of ternary zinc nitride semiconductors using first-principles calculations of electronic structure, stability and dopability. This approach identifies as-yet-unreported CaZn2N2 that has earth-abundant components, smaller carrier effective masses than gallium nitride and a tunable direct bandgap suited for light emission and harvesting. High-pressure synthesis realizes this phase, verifying the predicted crystal structure and band-edge red photoluminescence. In total, we propose 21 promising systems, including Ca2ZnN2, Ba2ZnN2 and Zn2PN3, which have not been reported as semiconductors previously. Given the variety in bandgaps of the identified compounds, the present study expands the potential suitability of nitride semiconductors for a broader range of electronic, optoelectronic and photovoltaic applications. PMID:27325228

  13. Discovery of earth-abundant nitride semiconductors by computational screening and high-pressure synthesis.

    Science.gov (United States)

    Hinuma, Yoyo; Hatakeyama, Taisuke; Kumagai, Yu; Burton, Lee A; Sato, Hikaru; Muraba, Yoshinori; Iimura, Soshi; Hiramatsu, Hidenori; Tanaka, Isao; Hosono, Hideo; Oba, Fumiyasu

    2016-06-21

    Nitride semiconductors are attractive because they can be environmentally benign, comprised of abundant elements and possess favourable electronic properties. However, those currently commercialized are mostly limited to gallium nitride and its alloys, despite the rich composition space of nitrides. Here we report the screening of ternary zinc nitride semiconductors using first-principles calculations of electronic structure, stability and dopability. This approach identifies as-yet-unreported CaZn2N2 that has earth-abundant components, smaller carrier effective masses than gallium nitride and a tunable direct bandgap suited for light emission and harvesting. High-pressure synthesis realizes this phase, verifying the predicted crystal structure and band-edge red photoluminescence. In total, we propose 21 promising systems, including Ca2ZnN2, Ba2ZnN2 and Zn2PN3, which have not been reported as semiconductors previously. Given the variety in bandgaps of the identified compounds, the present study expands the potential suitability of nitride semiconductors for a broader range of electronic, optoelectronic and photovoltaic applications.

  14. Analysis on Earth Conveying and Pressure Maintaining of Screw Conveyors of EPB Shields%土压平衡盾构螺旋输送机排土及保压作用分析

    Institute of Scientific and Technical Information of China (English)

    周冠南

    2012-01-01

    The earth conveying and pressure maintaining of screw conveyors play an important role in the safe and effi- cient boring of EPB shields. The working principles and influencing factors of the earth conveying and pressure maintai- ning of screw conveyors are systematically analyzed. Conclusions drawn are as follows : 1 ) The earth pressure balance in the boring of EPB shields includes the pressure balance between inside chamber and outside chamber, the pressure bal- ance inside the screw conveyor, and the earth input/output volume balance, which can be realized by controlling the volume of earth conveyed. 2) When the earth enters the screw conveyors, the water/soil pressure in the chamber is re- sisted by the gravity of the earth and the friction with the screw rod, lamina and the inner side of the conveyor, so as to keep stable earth conveying. 3 ) The earth behavior, which has great influence on the earth conveying and pressure maintaining of screw conveyors, can be improved by injecting ground conditioning agents into areas ahead of the cutter heads and into the chamber. 4) Regarding the structure of the screw conveyor, the pressure maintaining effect can be improved by means of reducing the pitch, adopting discontinuous screw and double screw conveyors.%螺旋输送机的排土和保压作用的发挥对土压平衡盾构的施工安全与效率有重要影响,对其作用机制及影响其作用发挥的因素进行系统的理论分析,并参考工程实测数据,得出以下结论:1)盾构施工中的土压平衡包括土仓内外与螺旋输送机内的压力平衡和进、出土量的平衡,其通过螺旋输送机排土量的控制来实现;2)渣土进入螺旋输送机后,依靠自身重力及与螺杆、叶片和筒壁界面间的摩擦作用来抵抗土仓内的水土压力,保持出渣过程的稳定性;3)渣土性质对螺旋输送机的排土和保压效果有较大影响,主要通过向刀盘前方和土仓内添加改良材料的

  15. Stress in highly demanding IT jobs: transformational leadership moderates the impact of time pressure on exhaustion and work-life balance.

    Science.gov (United States)

    Syrek, Christine J; Apostel, Ella; Antoni, Conny H

    2013-07-01

    The objective of this article is to investigate transformational leadership as a potential moderator of the negative relationship of time pressure to work-life balance and of the positive relationship between time pressure and exhaustion. Recent research regards time pressure as a challenge stressor; while being positively related to motivation and performance, time pressure also increases employee strain and decreases well-being. Building on the Job Demand-Resources model, we hypothesize that transformational leadership moderates the relationships between time pressure and both employees' exhaustion and work-life balance such that both relationships will be weaker when transformational leadership is higher. Of seven information technology organizations in Germany, 262 employees participated in the study. Established scales for time pressure, transformational leadership, work-life balance, and exhaustion were used, all showing good internal consistencies. The results support our assumptions. Specifically, we find that under high transformational leadership the impact of time pressure on exhaustion and work-life balance was less strong. The results of this study suggest that, particularly under high time pressure, transformational leadership is an important factor for both employees' work-life balance and exhaustion.

  16. Energy balance in the solar transition region. II - Effects of pressure and energy input on hydrostatic models

    Science.gov (United States)

    Fontenla, J. M.; Avrett, E. H.; Loeser, R.

    1991-01-01

    The radiation of energy by hydrogen lines and continua in hydrostatic energy-balance models of the transition region between the solar chromosphere and corona is studied using models which assume that mechanical or magnetic energy is dissipated in the hot corona and is then transported toward the chromosphere down the steep temperature gradient of the transition region. These models explain the average quiet sun and also the entire range of variability of the Ly-alpha lines. The relations between the downward energy flux, the pressure of the transition region, and the different hydrogen emission are described.

  17. South Dakota Space Grant Consortium: Balancing Indigenous Earth System and Space Science with Western/Contemporary Science

    Science.gov (United States)

    Bolman, J.; Nall, J.

    2005-05-01

    The South Dakota Space Grant Consortium (SDSGC) was established March 1, 1991 by a NASA Capability Enhancement Grant. Since that time SDSGC has worked to provide earth system and space science education, outreach and services to all students across South Dakota. South Dakota has nine tribes and five Tribal Colleges. This has presented a tremendous opportunity to develop sustainable equitable partnerships and collaborations. SDSGC believes strongly in developing programs and activities that highlight and reinforce the balance of Indigenous science and ways of knowing with current findings in Western/Contemporary Science. This blending of science and culture creates a learning community where individuals especially students, can gain confidence and pride in their unique skills and abilities. Universities are also witnessing the accomplishments and achievements of students who are able to experience a tribal environment and then carry that experience to a college/university/workplace and significantly increase the learning achievement of all. The presentation will highlight current Tribal College and Tribal Community partnerships with the Rosebud Sioux Reservation (Sinte Gleska University), Pine Ridge Indian Reservation (Oglala Lakota College), Standing Rock Sioux Reservation (Sitting Bull College) and Cheyenne River Sioux Reservation (Si Tanka) amongst others. Programs and activities to be explained during the presentation include but not limited to: NASA Workforce Native Connections, Scientific Knowledge for Indian Learning and Leadership (SKILL), NSF "Bridges to Success" Summer Research Program, NSF "Fire Ecology" Summer Research Experience, as well as geospatial and space science programs for students and general community members. The presentation will also cover the current initiatives underway through NASA Workforce Development. These include: partnering with the Annual He Sapa Wacipi (Black Hills Pow Wow - attendance of 14,000 Natives) to host Native Space

  18. High intensity positive pressure ventilation and long term pulmonary function responses in severe stable COPD. A delicate and difficult balance.

    Science.gov (United States)

    Esquinas, Antonio M; Petroianni, Angelo

    2014-06-01

    Method to improve minute ventilation (MV) during spontaneous breathing (SB) in stable severe chronic obstructive pulmonary disease (COPD) have a great clinical relevant in long term outcome. In this scenario, recommendations of early use of high-Intensity non-invasive Positive pressure Ventilation (HI-NPPV) or intelligent Volume Assured Pressure (iVAP) Support in Hypercapnic COPD have been proposed by safe therapeutics options. We analyze in this letter, Ekkernkamp et al. study that described the effect of HI-NPPV compared with SB on MV in patients receiving long-term treatment. We consider that interpretation of relationships between ABG, functional parameters, and respiratory mechanics reported need clarifications. Further prospective large clinical trials identifying the best mode of ventilation according to the characteristics in severe stable COPD are necessary to balance an effective approach and response on clinical symptoms and long-term effects.

  19. The effects of oblateness and solar radiation pressure on halo orbits in the photogravitational Sun-Earth system

    Science.gov (United States)

    Srivastava, Vineet K.; Kumar, Jai; Kushvah, Badam Singh

    2016-12-01

    In this paper, we construct a third-order analytic approximate solution using the Lindstedt-Poincare method in the photogravitational circular restricted three body problem considering the Sun as a radiating source and the Earth as an oblate spheroid for computing halo orbits around the collinear Lagrangian points L1 and L2. Further, the well-known differential correction and continuation schemes are used to compute halo orbits and their families numerically. The effects of solar radiation pressure and oblateness on the orbit are studied around both Lagrangian points. From the study, it is noticed that time period of the halo orbit increases around L1 and L2 accounting oblateness of the Earth and solar radiation pressure of the Sun. It is also found that stability of halo orbits is a weak function of the out-of-plane amplitude and mass reduction factor.

  20. Stress State of Elastic Thick-Walled Ring With Self-Balanced Pressures Distributed on Its Internal and External Borders

    Directory of Open Access Journals (Sweden)

    Kravchuk Aleksandr Stepanovich

    2015-10-01

    Full Text Available For the first time with the help of the theory of analytic functions and Kolosov-Muskhelishvili formulas the problem of the two-dimensional theory of elasticity for a thickwalled ring with the uneven pressures, acting on its borders, was solved. The pressure on the inner and outer boundaries is represented by Fourier series. The authors represent the two complex functions which solve boundary problem in the form of Laurent series. The logarithmic terms in these series are absent because the boundary problem has the self-balancing loads on each boundary of ring. The coefficients in the Laurent series are calculated by the boundary conditions. Firstly, the equations were obtained in the general form. But the hypothesis about even distributions of pressures at borders of ring was used for constructing an example. It leads to the fact that all coefficients of analytic functions represented in Laurent series have to be only real. As a solving example, the representation of pressures in equivalent hypotrochoids was used. The application of the computer algebra system Mathematica greatly simplifies the calculation of the distribution of stresses and displacements in ring. It does not require manual formal separation of real and imaginary parts in terms of Kolosov-Muskhelishvili to display the distribution of the physical parameters. It separates them only for calculated numbers with the help of built-in functions.

  1. Measuring Center of Pressure Signals to Quantify Human Balance Using Multivariate Multiscale Entropy by Designing a Force Platform

    Directory of Open Access Journals (Sweden)

    Cheng-Wei Huang

    2013-08-01

    Full Text Available To assess the improvement of human body balance, a low cost and portable measuring device of center of pressure (COP, known as center of pressure and complexity monitoring system (CPCMS, has been developed for data logging and analysis. In order to prove that the system can estimate the different magnitude of different sways in comparison with the commercial Advanced Mechanical Technology Incorporation (AMTI system, four sway tests have been developed (i.e., eyes open, eyes closed, eyes open with water pad, and eyes closed with water pad to produce different sway displacements. Firstly, static and dynamic tests were conducted to investigate the feasibility of the system. Then, correlation tests of the CPCMS and AMTI systems have been compared with four sway tests. The results are within the acceptable range. Furthermore, multivariate empirical mode decomposition (MEMD and enhanced multivariate multiscale entropy (MMSE analysis methods have been used to analyze COP data reported by the CPCMS and compare it with the AMTI system. The improvements of the CPCMS are 35% to 70% (open eyes test and 60% to 70% (eyes closed test with and without water pad. The AMTI system has shown an improvement of 40% to 80% (open eyes test and 65% to 75% (closed eyes test. The results indicate that the CPCMS system can achieve similar results to the commercial product so it can determine the balance.

  2. Simplification of hydraulic balance without differential pressure regulators; Vereinfachung des hydraulischen Abgleichs. Wegfall der Differenzdruckregler

    Energy Technology Data Exchange (ETDEWEB)

    Gebauer, Marc [W. Baelz und Sohn GmbH und Co., Heilbronn (Germany)

    2010-12-15

    In many heating systems, it would be possible to reduce the number of armatures to save energy. The author presents an example to show the shortcomings of systems with differential pressure controllers and recirculation pumps and points out the advantages of jet pump control. (orig.)

  3. Sodium-potassium balance in the regulation of high blood pressure

    Directory of Open Access Journals (Sweden)

    Luis Hernán Zárate Méndez

    2012-02-01

    Full Text Available The World Health Organization considers essential hypertension as a primary cause of death. Twenty-five percent of the population over 15 has high blood pressure (HBP, equivalent to a billion people. It has been predicted that this group will increase by 60%, lineal with age increase in the overall population. Unfortunately, detection, treatment and effective control of HBP, are deficient both in Chile and in the rest of the world, making it an unresolved health problem demanding urgent attention. The recently conducted Chilean National Health Survey (2009-2010 revealed a 26.9% prevalence of this condition in the population, sixty-five percent of individuals are aware of their condition, 37.6% are in treatment and only 16,49% are effectively controlled. Furthermore, the survey reveals unhealthy life-style markers, which explains the epidemic that besets the country as there are multiple risk factors at stake. This review focuses mainly on the importance of the sodium-potassium relationship in the regulation of high blood pressure. It must be pointed out that all of the studies underscore the importance of sodium in the genesis of hypertension because of its effects of blood pressure, especially in sensitive individuals, while little attention has been given to the manifold beneficial actions of potassium in the regulation of blood pressure.

  4. High pressure effects on the superconductivity in rare-earth-doped CaFe2As2

    Science.gov (United States)

    Uhoya, Walter; Cargill, Daniel; Gofryk, Krzysztof; Tsoi, Georgiy M.; Vohra, Yogesh K.; Sefat, Athena S.; Weir, S. T.

    2014-01-01

    High pressure superconductivity in a rare-earth-doped Ca0.86Pr0.14Fe2As2 single-crystalline sample has been studied up to 12 GPa and temperatures down to 11 K using the designer diamond anvil cell under a quasi-hydrostatic pressure medium. The electrical resistance measurements were complemented by high pressure and low-temperature X-ray diffraction studies at a synchrotron source. The electrical resistance measurements show an intriguing observation of superconductivity under pressure, with Tc as high as ∼51 K at 1.9 GPa, presenting the highest Tc reported in the intermetallic class of 122 iron-based superconductors. The resistive transition observed suggests a possible existence of two superconducting phases at low pressures of 0.5 GPa: one phase starting at Tc1 ∼ 48 K and the other starts at Tc2 ∼ 16 K. The two superconducting transitions show distinct variations with increasing pressure. High pressure and low-temperature structural studies indicate that the superconducting phase is a collapsed tetragonal ThCr2Si2-type (122) crystal structure.

  5. Origin of “memory glass” effect in pressure-amorphized rare-earth molybdate single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Willinger, Elena, E-mail: kudrenko@fhi-berlin.mpg.de [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation); Fritz-Haber Institute of the Max Planck Society, 14195 Berlin (Germany); Sinitsyn, Vitaly; Khasanov, Salavat; Redkin, Boris; Shmurak, Semeon; Ponyatovsky, Eugeny [Institute of Solid State Physics, Russian Academy of Sciences, 142432 Chernogolovka (Russian Federation)

    2015-02-15

    The memory glass effect (MGE) describes the ability of some materials to recover the initial structure and crystallographic orientation after pressure-induced amorphization (PIA). In spite of numerous studies the nature and underlying mechanisms of this phenomenon are still not clear. Here we report investigations of MGE in β′-Eu{sub 2}(MoO{sub 4}){sub 3} single crystal samples subjected to high pressure amorphization. Using the XRD and TEM techniques we carried out detailed analysis of the structural state of high pressure treated single crystal samples as well as structural transformations due to subsequent annealing at atmospheric pressure. The structure of the sample has been found to be complex, mainly amorphous, however, the amorphous medium contains evenly distributed nanosize inclusions of a paracrystalline phase. The inclusions are highly correlated in orientation and act as “memory units” in the MGE. - Graphical abstract: Schematic representation of pressure-induced amorphization and “memory glass” effect in rare-earth molybdate single crystals. The XRD and TEM measurements have revealed the presence of the residual identically oriented paracrystalline nanodomains in the pressure-amorphized state. These domains preserve the information about initial structure and orientation of the sample. They act as memory units and crystalline seeds during transformation of the amorphous phase back to the starting single crystalline one. - Highlights: • Pressure-amorphized Eu{sub 2}(MoO4){sub 3} single crystals were studied ex-situ by XRD and TEM. • Tiny residual crystalline inclusions were found in amorphous matrix of sample. • The inclusions keep in memory the parent crystal structure and orientation. • The inclusions account for “memory glass” effect in rare-earth molibdates.

  6. Earth Inner Core Periodic Motion due to Pressure Difference Induced by Tidal Acceleration

    CERN Document Server

    Wolf, M

    2013-01-01

    The inner structure of the earth is still a topic of discussion. Seismic measurements showed a structure of solid, liquid, solid which describes the mantle, outer core and inner core with the inner core in the center. The analysis of waveform doublets suggests now that the inner core is out of center and even of faster rotation than the mantel and crust. From the sum of Buoyancy and Gravity on the earth inner core, the position energy is plotted and together with the tangential tidal acceleration, it is derived that Earth Inner Core cannot be in a center position without additional force. The Earth Core System is explained as Hydrodynamic Bearing. The Eccentricities out of nutation due to the effects from the sun and moon are calculated as an approximation.

  7. Turbulent kinetic energy balance measurements in the wake of a low-pressure turbine blade

    Energy Technology Data Exchange (ETDEWEB)

    Sideridis, A. [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Yakinthos, K., E-mail: kyros@eng.auth.g [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Goulas, A. [Laboratory of Fluid Mechanics and Turbomachinery, Department of Mechanical Engineering, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)

    2011-02-15

    The turbulent kinetic energy budget in the wake generated by a high lift, low-pressure two-dimensional blade cascade of the T106 profile was investigated experimentally using hot-wire anemometry. The purpose of this study is to examine the transport mechanism of the turbulent kinetic energy and provide validation data for turbulence modeling. Point measurements were conducted on a high spatial resolution, two-dimensional grid that allowed precise derivative calculations. Positioning of the probe was achieved using a high accuracy traversing mechanism. The turbulent kinetic energy (TKE) convection, production, viscous diffusion and turbulent diffusion were all obtained directly from experimental measurements. Dissipation and pressure diffusion were calculated indirectly using techniques presented and validated by previous investigators. Results for all terms of the turbulent kinetic energy budget are presented and discussed in detail in the present work.

  8. Pressure sensor-based tongue-placed electrotactile biofeedback for balance improvement - Biomedical application to prevent pressure sores formation and falls

    CERN Document Server

    Vuillerme, Nicolas; Pinsault, Nicolas; Moreau-Gaudry, Alexandre; Fleury, Anthony; Demongeot, Jacques; Payan, Yohan

    2007-01-01

    We introduce the innovative technologies, based on the concept of "sensory substitution", we are developing in the fields of biomedical engineering and human disability. Precisely, our goal is to design, develop and validate practical assistive biomedical and/or technical devices and/or rehabilitating procedures for persons with disabilities, using artificial tongue-placed tactile biofeedback systems. Proposed applications are dealing with: (1) pressure sores prevention in case of spinal cord injuries (persons with paraplegia, or tetraplegia); and (2) balance control improvement to prevent fall in older and/or disabled adults. This paper describes the architecture and the functioning principle of these biofeedback systems and presents preliminary results of two feasibility studies performed on young healthy adults.

  9. A Balanced Mixture of Antagonistic Pressures Promotes the Evolution of Parallel Movement

    Science.gov (United States)

    Demšar, Jure; Štrumbelj, Erik; Lebar Bajec, Iztok

    2016-12-01

    A common hypothesis about the origins of collective behaviour suggests that animals might live and move in groups to increase their chances of surviving predator attacks. This hypothesis is supported by several studies that use computational models to simulate natural evolution. These studies, however, either tune an ad-hoc model to ‘reproduce’ collective behaviour, or concentrate on a single type of predation pressure, or infer the emergence of collective behaviour from an increase in prey density. In nature, prey are often targeted by multiple predator species simultaneously and this might have played a pivotal role in the evolution of collective behaviour. We expand on previous research by using an evolutionary rule-based system to simulate the evolution of prey behaviour when prey are subject to multiple simultaneous predation pressures. We analyse the evolved behaviour via prey density, polarization, and angular momentum. Our results suggest that a mixture of antagonistic external pressures that simultaneously steer prey towards grouping and dispersing might be required for prey individuals to evolve dynamic parallel movement.

  10. Earth's air pressure 2.7 billion years ago constrained to less than half of modern levels

    Science.gov (United States)

    Som, Sanjoy M.; Buick, Roger; Hagadorn, James W.; Blake, Tim S.; Perreault, John M.; Harnmeijer, Jelte P.; Catling, David C.

    2016-06-01

    How the Earth stayed warm several billion years ago when the Sun was considerably fainter is the long-standing problem of the `faint young Sun paradox'. Because of negligible O2 and only moderate CO2 levels in the Archaean atmosphere, methane has been invoked as an auxiliary greenhouse gas. Alternatively, pressure broadening in a thicker atmosphere with a N2 partial pressure around 1.6-2.4 bar could have enhanced the greenhouse effect. But fossilized raindrop imprints indicate that air pressure 2.7 billion years ago (Gyr) was below twice modern levels and probably below 1.1 bar, precluding such pressure enhancement. This result is supported by nitrogen and argon isotope studies of fluid inclusions in 3.0-3.5 Gyr rocks. Here, we calculate absolute Archaean barometric pressure using the size distribution of gas bubbles in basaltic lava flows that solidified at sea level ~2.7 Gyr in the Pilbara Craton, Australia. Our data indicate a surprisingly low surface atmospheric pressure of Patm = 0.23 +/- 0.23 (2σ) bar, and combined with previous studies suggests ~0.5 bar as an upper limit to late Archaean Patm. The result implies that the thin atmosphere was rich in auxiliary greenhouse gases and that Patm fluctuated over geologic time to a previously unrecognized extent.

  11. Influence of geomagnetic activity and earth weather changes on heart rate and blood pressure in young and healthy population

    Science.gov (United States)

    Ozheredov, V. A.; Chibisov, S. M.; Blagonravov, M. L.; Khodorovich, N. A.; Demurov, E. A.; Goryachev, V. A.; Kharlitskaya, E. V.; Eremina, I. S.; Meladze, Z. A.

    2016-11-01

    There are many references in the literature related to connection between the space weather and the state of human organism. The search of external factors influence on humans is a multi-factor problem and it is well known that humans have a meteo-sensitivity. A direct problem of finding the earth weather conditions, under which the space weather manifests itself most strongly, is discussed in the present work for the first time in the helio-biology. From a formal point of view, this problem requires identification of subset (magnetobiotropic region) in three-dimensional earth's weather parameters such as pressure, temperature, and humidity, corresponding to the days when the human body is the most sensitive to changes in the geomagnetic field variations and when it reacts by statistically significant increase (or decrease) of a particular physiological parameter. This formulation defines the optimization of the problem, and the solution of the latter is not possible without the involvement of powerful metaheuristic methods of searching. Using the algorithm of differential evolution, we prove the existence of magnetobiotropic regions in the earth's weather parameters, which exhibit magneto-sensitivity of systolic, diastolic blood pressure, and heart rate of healthy young subjects for three weather areas (combinations of atmospheric temperature, pressure, and humidity). The maximum value of the correlation confidence for the measurements attributable to the days of the weather conditions that fall into each of three magnetobiotropic areas is an order of 0.006, that is almost 10 times less than the confidence, equal to 0.05, accepted in many helio-biological researches.

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

    Institute of Scientific and Technical Information of China (English)

    Geng Jie; You Benyue; Zhang Zhaodong

    2006-01-01

    The water level in a deep well instantly responds to the earth's tide and atmospheric pressure,and varies accordingly, not only in terms of amplitude but also in the phase lag. Therefore,phase lag correction is used in analyzing digital groundwater observation data in eastern China.Calculation results presented by the authors in this paper show that the correction method is effective in the identification of anomalous changes for short-term seismic precursors. The correction method can also be applied to the processing of observed deformation and tilt data.

  13. Electron pressure balance in the SOL through the transition to detachment

    Energy Technology Data Exchange (ETDEWEB)

    McLean, A.G., E-mail: mclean@fusion.gat.com [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Leonard, A.W.; Makowski, M.A. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Groth, M. [Aalto University, Espoo 02150 (Finland); Allen, S.L. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Boedo, J.A. [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Bray, B.D. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Briesemeister, A.R. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); Carlstrom, T.N. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Eldon, D. [University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093 (United States); Fenstermacher, M.E.; Hill, D.N.; Lasnier, C.J. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Liu, C.; Osborne, T.H.; Petrie, T.W. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Soukhanovskii, V.A. [Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Stangeby, P.C.; Tsui, C. [University of Toronto Institute for Aerospace Studies, Toronto M3H 5T6 (Canada); Unterberg, E.A. [Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831 (United States); and others

    2015-08-15

    Upgrades to core and divertor Thomson scattering (DTS) diagnostics at DIII-D have provided measurements of electron pressure profiles in the lower divertor from attached- to fully-detached divertor plasma conditions. Detailed, multistep sequences of discharges with increasing line-averaged density were run at several levels of P{sub inj}. Strike point sweeping allowed 2D divertor characterization using DTS optimized to measure T{sub e} down to 0.5 eV. The ionization front at the onset of detachment is found to move upwards in a controlled manner consistent with the indication that scrape-off layer parallel power flux is converted from conducted to convective heat transport. Measurements of n{sub e}, T{sub e} and p{sub e} in the divertor versus L{sub parallel} demonstrate a rapid transition from T{sub e} ⩾ 15 eV to ⩽3 eV occurring both at the outer strike point and upstream of the X-point. These observations provide a strong benchmark for ongoing modeling of divertor detachment for existing and future tokamak devices.

  14. Contrasting effects of vasodilators on blood pressure and sodium balance in the hypertension of autonomic failure

    Science.gov (United States)

    Jordan, J.; Shannon, J. R.; Pohar, B.; Paranjape, S. Y.; Robertson, D.; Robertson, R. M.; Biaggioni, I.

    1999-01-01

    Supine hypertension, which is very common in patients with autonomic failure, limits the use of pressor agents and induces nighttime natriuresis. In 13 patients with severe orthostatic hypotension due to autonomic failure (7 women, 6 men, 72 +/- 3 yr) and supine hypertension, the effect of 30 mg nifedipine (n = 10) and 0.025 to 0.2 mg/h nitroglycerin patch (n = 11) on supine BP, renal sodium handling, and orthostatic tolerance was determined. Medications were given at 8 p.m.; patients stood up at 8 a.m. Nitroglycerin was removed at 6 a.m. Compared with placebo, nifedipine and nitroglycerin decreased systolic BP during the night by a maximum of 37 +/- 9 and 36 +/- 10 mmHg, respectively (P hypertension in patients with autonomic failure. However, nifedipine has a prolonged depressor effect and worsens orthostatic hypotension in the morning. The decrease in pressure natriuresis that would be expected with the substantial decrease in BP obtained with nitroglycerin and nifedipine may be offset by a direct effect of both drugs on renal sodium handling.

  15. Pressure and Ionization Balances in the Circum-Heliospheric Interstellar Medium and the Local Bubble

    CERN Document Server

    Jenkins, Edward B

    2008-01-01

    A disconcerting mismatch of thermal pressures for two media in contact with each other, (1) the warm, Circum-heliospheric Interstellar Medium (CHISM) and (2) the very hot material within a much larger region called the Local Bubble (LB), has troubled astronomers for over two decades. A possible resolution of this problem, at least in part, now seems possible. We now understand that earlier estimates for the average electron density in the very hot LB plasma were inflated by an unrecognized foreground contamination to the low energy diffuse X-ray background measurements. This foreground illumination arises from photons emitted by charge exchange reactions between solar wind ions and neutral atoms from the interstellar medium that enter into the heliosphere. However, with the resolution of this problem comes a new one. The high ionization fraction of helium in the CHISM, relative to that of hydrogen, could be understood in terms of the effects from a strong flux of EUV and X-ray radiation coming from both the L...

  16. The Role of Cerenkov Radiation in the Pressure Balance of Cool Core Clusters of Galaxies

    Science.gov (United States)

    Lieu, Richard

    2017-03-01

    Despite the substantial progress made recently in understanding the role of AGN feedback and associated non-thermal effects, the precise mechanism that prevents the core of some clusters of galaxies from collapsing catastrophically by radiative cooling remains unidentified. In this Letter, we demonstrate that the evolution of a cluster's cooling core, in terms of its density, temperature, and magnetic field strength, inevitably enables the plasma electrons there to quickly become Cerenkov loss dominated, with emission at the radio frequency of ≲350 Hz, and with a rate considerably exceeding free–free continuum and line emission. However, the same does not apply to the plasmas at the cluster's outskirts, which lacks such radiation. Owing to its low frequency, the radiation cannot escape, but because over the relevant scale size of a Cerenkov wavelength the energy of an electron in the gas cannot follow the Boltzmann distribution to the requisite precision to ensure reabsorption always occurs faster than stimulated emission, the emitting gas cools before it reheats. This leaves behind the radiation itself, trapped by the overlying reflective plasma, yet providing enough pressure to maintain quasi-hydrostatic equilibrium. The mass condensation then happens by Rayleigh–Taylor instability, at a rate determined by the outermost radius where Cerenkov radiation can occur. In this way, it is possible to estimate the rate at ≈2 M ⊙ year‑1, consistent with observational inference. Thus, the process appears to provide a natural solution to the longstanding problem of “cooling flow” in clusters; at least it offers another line of defense against cooling and collapse should gas heating by AGN feedback be inadequate in some clusters.

  17. Chemical pressure and hidden one-dimensional behavior in rare earth tri-telluride

    Energy Technology Data Exchange (ETDEWEB)

    Sacchetti, A.; Degiorgi, L.; /Zurich, ETH; Giamarchi, T.; /Geneva U.; Ru, N.; Fisher, I.R.; /Stanford U., Geballe Lab.

    2009-12-14

    We report on the first optical measurements of the rare-earth tri-telluride charge-density-wave systems. Our data, collected over an extremely broad spectral range, allow us to observe both the Drude component and the single-particle peak, ascribed to the contributions due to the free charge carriers and to the charge-density-wave gap excitation, respectively. The data analysis displays a diminishing impact of the charge-density-wave condensate on the electronic properties with decreasing lattice constant across the rare-earth series. We propose a possible mechanism describing this behavior and we suggest the presence of a one-dimensional character in these two-dimensional compounds. We also envisage that interactions and umklapp processes might play a relevant role in the formation of the charge-density-wave state in these compounds.

  18. Seismic active earth pressure of retaining wall%地震作用下挡土墙主动土压力分布

    Institute of Scientific and Technical Information of China (English)

    张永兴; 陈林

    2012-01-01

    The basic analysis equations were set up by considering the equilibrium of the forces on a thin-layer element of the wedge. By using the equilibrium equation of the moments on the whole wedge, the lateral coefficient of earth pressure, and the earth pressure distribution along the wall were obtained. The effects of seismic coefficient on the lateral coefficient of earth pressure and the distribution of earth pressures were investigated. The results show that the lateral earth pressure coefficient increases as the horizontal seismic coefficient increases. The effect of the vertical seismic coefficient is more complicated. If the vertical seismic coefficient is less than zero, the lateral earth pressure coefficient decreases as the vertical seismic coefficient increases; If the vertical seismic coefficient is greater than zero, the lateral earth pressure coefficient increases as the vertical seismic coefficient increases; the maximum earth pressure gradually decreases as the vertical seismic coefficient increases. The maximum earth pressure first decreases and then increases as the horizontal seismic coefficient increases; as the increase of the vertical and horizontal seismic coefficient increases, the position of the maximum lateral seismic earth pressure moves gradually to the top of the wall, but near the bottom of the wall, the relative value of the earth pressure decreases, and near the top of the wall, the relative value of the earth pressure increases. Theproposed method was verified by some experiment data. The calculated resultant and maximum earth pressure agree well with the experiment results. The effect of seismic coefficient on the points of application of the resultant earth pressure was investigated. The proposed method was compared with the Mononobe-Okabe's theory. The results indicate that it is dangerous for the overturning stability of retaining walls with the translational movement mode if they are designed according to the Mononobe

  19. High-pressure phase transitions in the rare-earth orthoferrite LaFeO3.

    Science.gov (United States)

    Etter, Martin; Müller, Melanie; Hanfland, Michael; Dinnebier, Robert E

    2014-06-01

    Sequential Rietveld refinements were applied on high-pressure synchrotron powder X-ray diffraction measurements of lanthanum ferrite (LaFeO3) revealing two phase transitions on the room-temperature isotherm up to a pressure of 48 GPa. The first structural phase transition of second order occurs at a pressure of 21.1 GPa, changing the space group from Pbnm to Ibmm. The second transition, involving a isostructural first-order phase transition, occurs at approximately 38 GPa, indicating a high-spin to low-spin transition of the Fe(3+) ion. Following the behavior of the volume up to the hydrostatic limit of methanol-ethanol it was possible to use inverted equations of state (EoS) to determine a bulk modulus of B0 = 172 GPa and a corresponding pressure derivative of B'0 = 4.3. In addition, the linearized version of the inverted EoS were used to determine the corresponding moduli and pressure derivatives for each lattice direction.

  20. The effect of different skin-ankle brace application pressures on quiet single-limb balance and electromyographic activation onset of lower limb muscles

    Directory of Open Access Journals (Sweden)

    Papadakis Stamatios A

    2007-09-01

    Full Text Available Abstract Background Several studies have been carried out in order to investigate the effect of ankle bracing on ankle joint function and performance. However, no study so far has examined the role of skin-brace interface pressure in neuromuscular control. The aim of this study was to investigate the effect of different skin-ankle brace interface pressures on quiet single limb balance and the electromyographic (EMG activation sequence of four lower limb muscles. Methods Thirty three male physical education students who volunteered to take part in the study were measured under three ankle brace conditions: i without brace, ii with brace and 30 kPa application pressure and iii with brace and 60 kPa application pressure. Single limb balance (anteroposterior and mediolateral parameter was assessed on the dominant lower limb, with open and closed eyes, on a force platform, simultaneously with the EMG recording of four lower lower limb muscles' (gastrocnemius, peroneus longus, rectus femoris and biceps femoris activation onset. Results The results showed that overall balance (total stability parameter was not significantly affected in any of the three ankle brace conditions. However, the anteroposterior centre of pressure excursion and centre of pressure excursion velocity were significantly increased with the application of ankle brace, both with 30 and 60 kPa application pressures. Furthermore, it was found that single limb balance was significantly worse with closed eyes compared to open eyes. EMG measurements showed that the sequence of lower limb activation onset was not affected in any of the three ankle brace application conditions. The results of this study showed that the application of an ankle brace with two different skin-brace interface pressures had no effect on overall single limb balance and the sequence of lower limb muscle activation. Conclusion These findings suggest that peripheral joint receptors are either not adequately

  1. Cenosphere formation from heavy fuel oil: a numerical analysis accounting for the balance between porous shells and internal pressure

    KAUST Repository

    Vanteru, Mahendra Reddy

    2016-01-18

    Heavy fuel oil (HFO) as a fuel in industrial and power generation plants ensures the availability of energy at economy. Coke and cenosphere emissions from HFO combustion need to be controlled by particulate control equipment such as electrostatic precipitators, and collection effectiveness is impacted by the properties of these particulates. The cenosphere formation is a function of HFO composition, which varies depending on the source of the HFO. Numerical modelling of the cenosphere formation mechanism presented in this paper is an economical method of characterising cenosphere formation potential for HFO in comparison to experimental analysis of individual HFO samples, leading to better control and collection. In the present work, a novel numerical model is developed for understanding the global cenosphere formation mechanism. The critical diameter of the cenosphere is modelled based on the balance between two pressures developed in an HFO droplet. First is the pressure (Prpf) developed at the interface of the liquid surface and the inner surface of the accumulated coke due to the flow restriction of volatile components from the interior of the droplet. Second is the pressure due to the outer shell strength (PrC) gained from van der Walls energy of the coke layers and surface energy. In this present study it is considered that when PrC ≥ Prpf the outer shell starts to harden. The internal motion in the shell layer ceases and the outer diameter (DSOut) of the shell is then fixed. The entire process of cenosphere formation in this study is analysed in three phases: regression, shell formation and hardening, and post shell hardening. Variations in pressures during shell formation are analysed. Shell (cenosphere) dimensions are evaluated at the completion of droplet evaporation. The rate of fuel evaporation, rate of coke formation and coke accumulation are analysed. The model predicts shell outer diameters of 650, 860 and 1040 µm, and inner diameters are 360, 410

  2. Energy balance during intense and super-intense magnetic storms using an Akasofu ɛ parameter corrected by the solar wind dynamic pressure

    Science.gov (United States)

    de Lucas, A.; Gonzalez, W. D.; Echer, E.; Guarnieri, F. L.; Dal Lago, A.; da Silva, M. R.; Vieira, L. E. A.; Schuch, N. J.

    2007-11-01

    Geomagnetic storms are large disturbances in the Earth's magnetosphere caused by enhanced solar wind magnetosphere energy transfer. One of the main manifestations of a geomagnetic storm is the ring current enhancement. It is responsible for the decrease in the geomagnetic field observed at ground stations. In this work, we study the ring current dynamics during two different levels of magnetic storms. Thirty-three events are selected during the period 1981 2004. Eighteen out of 33 events are very intense (or super-intense) magnetic storms (Dst ⩽-250 nT) and the remaining are intense magnetic storms (-250ISEE-3) and geomagnetic indices (Dst and Sym-H) are analyzed. Our aim is to evaluate the interplanetary characteristics (interplanetary dawn dusk electric field, interplanetary magnetic field component BS), the ɛ parameter, and the total energy input into the magnetosphere (Wɛ) for these two classes of magnetic storms. Two corrections on the ɛ energy coupling function are made: the first one is an already known correction in the magnetopause radius to take into account the variation in the solar wind pressure. The second correction on the Akasofu parameter, first proposed in this work, accounts for the reconnection efficiency as a function of the solar wind ram pressure. Geomagnetic data/indices are also employed to study the ring current dynamics and to search for the differences in the storm evolution during these events. Our corrected ɛ parameter is shown to be more adequate to explain storm energy balance because the energy input and the energy dissipated in the ring current are in better agreement with modern estimates as compared with previous works. For super-intense storms, the correction of the Akasofu ɛ is on average a scaling factor of 3.7, whilst for intense events, this scaling factor is on average 3.4. The injected energy during the main phase using corrected ɛ can be considered a criterion to separate intense from very intense storms. Other

  3. 27.3-day and Average 13.6-day Periodic Oscillations in the Earth's Rotation Rate and Atmospheric Pressure Fields Due to Celestial Gravitation Forcing

    Institute of Scientific and Technical Information of China (English)

    LI Guoqing; ZONG Haifeng; ZHANG Qingyun

    2011-01-01

    Variation in length of day of the Earth (LOD equivalent to the Earth's rotation rate) versus change in atmospheric geopotential height fields and astronomical parameters were analyzed for the years 1962-2006.This revealed that there is a 27.3-day and an average 13.6-day periodic oscillation in LOD and atmospheric pressure fields following lunar revolution around the Earth. Accompanying the alternating change in celestial gravitation forcing on the Earth and its atmosphere, the Earth's LOD changes from minimum to maximum,then to minimum. and the atmospheric geopotential height fields in the tropics oscillate from low to high,then to low. The 27.3-day and average 13.6-day periodic atmospheric oscillation in the tropics is proposed to be a type of strong atmospheric tide, excited by celestial gravitation forcing. A formula for a Tidal Index was derived to estimate the strength of the celestial gravitation forcing, and a high degree of correlation was found between the Tidal Index determined by astronomical parameters, LOD, and atmospheric geopotential height. The reason for the atmospheric tide is periodic departure of the lunar orbit from the celestial equator during lunar revolution around the Earth. The alternating asymmetric change in celestial gravitation forcing on the Earth and its atmosphere produces a "modulation" to the change in the Earth's LOD and atmospheric pressure fields.

  4. 矿井自动控制均压防灭火系统设计%Design on Automatic Pressure Balanced Fire Prevention and Control System in Mine

    Institute of Scientific and Technical Information of China (English)

    朱红青; 李峰; 姜元刚; 潘凤龙; 郝俊伟

    2012-01-01

    With a fluid numerical simulation software, the pressure balanced effect was simulated and analyzed. According to the princi- ple and features of the pressure balanced fire prevention and control technology and the relationship between the two end pressure variation and air leakage value of the pressure balance area, the pressure regulated redundancy of the automatic control pressure balanced fire pre- vention and control system was determined. According to the frequent pressure regulation, pressure regulated delay, low pressure regula- ted accuracy and other problems existed in the manual pressure regulation, based on the CAN bus communication protocol, a mine auto- matic control pressure balanced fire prevention and control system was designed. A detail design was conducted on the automatic control system of the air regulator. According to the delay of the air leakage pressure difference signal transmission, the Smith prediction with PID control and regulation method was applied to regulate the air leakage and air pressure. Taking a mine in Shanxi as an example, the pres- sure balanced simulation results showed that before and after the pressure balanced, the width of the spontaneous combustion zone in the goaf was reduced from 70 m to 20 m and the distribution of the spontaneous combustion "three zones" was changed from disorder status to regular status.%利用流体数值模拟软件,对均压效果进行了模拟分析;根据均压防灭火技术原理、特点与均压区域两端压力变化和漏风量的关系,确定了自动控制均压防灭火系统的调压冗余度。针对手动均压中存在频繁调压、调压滞后与调压精度低等问题,基于CAN总线通信协议,设计了矿井自动控制均压防灭火系统;同时对风窗自动调节系统进行设计;根据漏风压差信号传递的滞后性,采用Smith预估和PID控制调节方法调节漏风风压。以山西某矿为例,均压模拟结果表明:均压前

  5. From Science Reserves to Sustainable Multiple Uses beyond Earth orbit: Evaluating Issues on the Path towards Balanced Environmental Management on Planetary Bodies

    Science.gov (United States)

    Race, Margaret

    Over the past five decades, our understanding of space beyond Earth orbit has been shaped by a succession of mainly robotic missions whose technologies have enabled scientists to answer diverse science questions about celestial bodies across the solar system. For all that time, exploration has been guided by planetary protection policies and principles promulgated by COSPAR and based on provisions in Article IX of the Outer Space Treaty of 1967. Over time, implementation of the various COSPAR planetary protection policies have sought to avoid harmful forward and backward contamination in order to ensure the integrity of science findings, guide activities on different celestial bodies, and appropriately protect Earth whenever extraterrestrial materials have been returned. The recent increased interest in extending both human missions and commercial activities beyond Earth orbit have prompted discussions in various quarters about the need for updating policies and guidelines to ensure responsible, balanced space exploration and use by all parties, regardless whether activities are undertaken by governmental or non-governmental entities. Already, numerous researchers and workgroups have suggested a range of different ways to manage activities on celestial environments (e.g, wilderness parks, exclusion zones, special regions, claims, national research bases, environmental impact assessments, etc.). While the suggestions are useful in thinking about how to manage future space activities, they are not based on any systematically applied or commonly accepted criteria (scientific or otherwise). In addition, they are borrowed from terrestrial approaches for environmental protection, which may or may not have direct applications to space environments. As noted in a recent COSPAR-PEX workshop (GWU 2012), there are no clear definitions of issues such as harmful contamination, the environment to be protected, or what are considered reasonable activity or impacts for particular

  6. Windsock memory conditioned RAM (Co-Ram) pressure effect: forced reconnection in the Earth's magnetotail

    CERN Document Server

    Vörös, Z; Khodachenko, M; Honkonen, I; Janhunen, P; Palmroth, M

    2014-01-01

    Magnetic reconnection (MR) is a key physical concept explaining the addition of magnetic flux to the magnetotail and closed flux lines back-motion to the dayside magnetosphere. This scenario elaborated by \\citet{dung63}, can explain many aspects of solar wind-magnetosphere interaction processes, including substorms. However, neither the Dungey model nor its numerous modifications were able to explain fully the onset conditions for MR in the tail. In this paper, we introduce new onset conditions for forced MR in the tail. We call our scenario the "windsock memory conditioned ram pressure effect". Our non-flux-transfer associated forcing is introduced by a combination of large-scale windsock motions exhibiting memory effects and solar wind dynamic pressure actions on the nightside magnetopause during northward oriented IMF. Using global MHD GUMICS-4 simulation results, upstream data from WIND, magnetosheath data from Cluster-1 and distant-tail data from the two-probe ARTEMIS mission, we show that the simultaneo...

  7. Comparison of Regression Methods to Compute Atmospheric Pressure and Earth Tidal Coefficients in Water Level Associated with Wenchuan Earthquake of 12 May 2008

    Science.gov (United States)

    He, Anhua; Singh, Ramesh P.; Sun, Zhaohua; Ye, Qing; Zhao, Gang

    2016-07-01

    The earth tide, atmospheric pressure, precipitation and earthquake fluctuations, especially earthquake greatly impacts water well levels, thus anomalous co-seismic changes in ground water levels have been observed. In this paper, we have used four different models, simple linear regression (SLR), multiple linear regression (MLR), principal component analysis (PCA) and partial least squares (PLS) to compute the atmospheric pressure and earth tidal effects on water level. Furthermore, we have used the Akaike information criterion (AIC) to study the performance of various models. Based on the lowest AIC and sum of squares for error values, the best estimate of the effects of atmospheric pressure and earth tide on water level is found using the MLR model. However, MLR model does not provide multicollinearity between inputs, as a result the atmospheric pressure and earth tidal response coefficients fail to reflect the mechanisms associated with the groundwater level fluctuations. On the premise of solving serious multicollinearity of inputs, PLS model shows the minimum AIC value. The atmospheric pressure and earth tidal response coefficients show close response with the observation using PLS model. The atmospheric pressure and the earth tidal response coefficients are found to be sensitive to the stress-strain state using the observed data for the period 1 April-8 June 2008 of Chuan 03# well. The transient enhancement of porosity of rock mass around Chuan 03# well associated with the Wenchuan earthquake (Mw = 7.9 of 12 May 2008) that has taken its original pre-seismic level after 13 days indicates that the co-seismic sharp rise of water well could be induced by static stress change, rather than development of new fractures.

  8. Elasticity of ferropericlase and seismic heterogeneity in the Earth's lower mantle: Ferropericlase High Pressure-Temperature Elasticity

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Jing [Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin Texas USA; Lin, Jung-Fu [Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin Texas USA; Center for High Pressure Science and Technology Advanced Research (HPSTAR), Shanghai China; Jacobsen, Steven D. [Department of Earth and Planetary Sciences, Northwestern University, Evanston Illinois USA; Seymour, Nikki M. [Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin Texas USA; Tkachev, Sergey N. [Center for Advanced Radiation Sources, University of Chicago, Chicago Illinois USA; Prakapenka, Vitali B. [Center for Advanced Radiation Sources, University of Chicago, Chicago Illinois USA

    2016-12-16

    Deciphering the origin of seismic heterogeneity has been one of the major challenges in understanding the geochemistry and geodynamics of the deep mantle. Fully anisotropic elastic properties of constituent minerals at relevant pressure-temperature conditions of the lower mantle can be used to calculate seismic heterogeneity parameters in order to better understand chemically and thermally induced seismic heterogeneities. In this study, the single-crystal elastic properties of ferropericlase (Mg0.94Fe0.06)O were measured using Brillouin spectroscopy and X-ray diffraction at conditions up to 50 GPa and 900 K. The velocity-density results were modeled using third-order finite-strain theory and thermoelastic equations along a representative geotherm to investigate high pressure-temperature and compositional effects on the seismic heterogeneity parameters. Our results demonstrate that from 660 to 2000 km, compressional wave anisotropy of ferropericlase increased from 4% to 9.7%, while shear wave anisotropy increased from 9% to as high as 22.5%. The thermally induced lateral heterogeneity ratio (RS/P = ∂lnVS/∂lnVP) of ferropericlase was calculated to be 1.48 at ambient pressure but decreased to 1.43 at 40 GPa along a representative geotherm. The RS/P of a simplified pyrolite model consisting of 80% bridgmanite and 20% ferropericlase was approximately 1.5, consistent with seismic models at depths from 670 to 1500 km, but showed an increased mismatch at lower mantle depths below ~1500 km. This discrepancy below mid-lower mantle could be due to either a contribution from chemically induced heterogeneity or the effects of the Fe spin transition in the deeper parts of the Earth's lower mantle.

  9. Thermal and Pressure Characterization of a Wind Tunnel Force Balance Using the Single Vector System. Experimental Design and Analysis Approach to Model Pressure and Temperature Effects in Hypersonic Wind Tunnel Research

    Science.gov (United States)

    Lynn, Keith C.; Commo, Sean A.; Johnson, Thomas H.; Parker, Peter A,

    2011-01-01

    Wind tunnel research at NASA Langley Research Center s 31-inch Mach 10 hypersonic facility utilized a 5-component force balance, which provided a pressurized flow-thru capability to the test article. The goal of the research was to determine the interaction effects between the free-stream flow and the exit flow from the reaction control system on the Mars Science Laboratory aeroshell during planetary entry. In the wind tunnel, the balance was exposed to aerodynamic forces and moments, steady-state and transient thermal gradients, and various internal balance cavity pressures. Historically, these effects on force measurement accuracy have not been fully characterized due to limitations in the calibration apparatus. A statistically designed experiment was developed to adequately characterize the behavior of the balance over the expected wind tunnel operating ranges (forces/moments, temperatures, and pressures). The experimental design was based on a Taylor-series expansion in the seven factors for the mathematical models. Model inversion was required to calculate the aerodynamic forces and moments as a function of the strain-gage readings. Details regarding transducer on-board compensation techniques, experimental design development, mathematical modeling, and wind tunnel data reduction are included in this paper.

  10. Validating the BTrackS Balance Plate as a low cost alternative for the measurement of sway-induced center of pressure.

    Science.gov (United States)

    O'Connor, Shawn M; Baweja, Harsimran S; Goble, Daniel J

    2016-12-08

    The BTrackS Balance Plate (BBP) is a low-cost force plate that provides objective balance assessment and true portability for the user. Given that this technology is relatively new, the purpose of the present study was to provide the first center of pressure (COP) validation of the BBP. Two BBP devices (one new and one used) were compared with a laboratory-grade force plate (LFP) during simultaneous collection of COP that was induced by an inverted pendulum device with human-like sway characteristics. The results of this study showed almost perfect agreement between the BBP devices and the LFP (ICC>0.999), as well as a high degree of BBP accuracy (cost solution for objective balance testing in the laboratory or clinic.

  11. Detection of Yarkovsky effect and solar radiation pressure on Near-Earth Asteroids

    Science.gov (United States)

    Faggioli, Laura; Del Vigna, Alessio; Milani, Andrea; Spoto, Federica; Valsecchi, Giovanni B.

    2016-10-01

    The orbit of small-sized asteroids can be affected by non-gravitational perturbations. When this happens, non-gravitational forces need to be taken into account since they are as important as collisions and gravitational perturbations for the overall understanding of the asteroid orbital evolution.The Yarkovsky effect and the Solar Radiation Pressure (SRP) are non-gravitational perturbations that can be modelled knowing the physical properties of asteroids, and whose consequences of the motions can be measured from accurate astrometry.The knowledge of the physical properties of asteroids is usually not sufficient to produce the thermophysical models needed for the computation of the Yarkovsky acceleration. Nevertheless, it can often be measured as a semimajor axis drift if the astrometric dataset contains extremely accurate observations (e.g. radar data), or if the observations span a sufficiently long time interval.Farnocchia et al. 2013 list 21 NEAs with a measurable semimajor-axis drift. Since 2013, the number of asteroids for which it is possible to detect the Yarkovsky effect has grown. This is due to the increased quality and time span of the observations, and to new radar measurements that have since become available. We are able to detect the Yarkovsky effect for more than 40 NEAs, employing a high precision dynamical model, including the Newtonian attraction of 16 massive asteroids and the planetary relativistic terms, and a suitable astrometric data treatment. We present a list of objects with a significant detection of Yarkovksy effect and a value compatible with the Yarkovsky mechanism.The computed non-gravitational perturbations will be added to the web portal of the ESA SSA-NEO Coordination Centre, highlighting the fact that the orbit has been computed taking the Yarkovsky effect or the SRP into account. The inclusion of non-gravitational perturbations can also affect the results of the impact monitoring, as in the case of (410777) 2009 FD, (29075

  12. Intercomparison of Primary Manometers in the Range 30 kPa to 110 kPa: Pressure Balance at the LNE and Mercury Manometer at the VNIIFTRI

    Science.gov (United States)

    Astrov, D. N.; Guillemot, J.; Legras, J. C.; Zakharov, A. A.

    1994-01-01

    An intercomparison between the primary pressure balance of the LNE and a mercury manometer developed at the All-Russian Research Institute for Physical, Technical and Radio-Technical Measurements (VNIIFTRI) for purposes of temperature measurement was undertaken in 1990. A short description of the two standards is given. The transfer standard was a pressure balance equipped with a piston-cylinder assembly that has the same characteristics as the standard of the Laboratoire National d'Essais (LNE). The results obtained from 30 kPa to 110 kPa showed a systematic relative difference of 12 parts in 106 between the two standards. This difference is significant, as the combined relative uncertainty at 1 σ level is estimated to be 4,2 parts in 106. These results are analysed in this paper.

  13. Changes in foot pressure elicited by 3D air balance exercise and pelvic stability exercise for functional leg-length discrepancy in adult women.

    Science.gov (United States)

    Lee, Byung-Hoon; Kim, Jeong-Ja; Kim, Chan-Kyu

    2015-03-01

    [Purpose] This study was conducted to examine the effect of pelvic stabilization exercise and 3D equipment exercise on adult women with Functional Leg-Length Discrepancy (FLLD). [Subjects and Methods] Twenty female students in their 20's having FLLD without Structural Leg Length Discrepancy were selected. Exercise was performed for 50 min per session, three times a week, for six weeks. The Pelvic stabilization exercise (PSE) group performed pelvic stabilization exercises for 50 minutes, and the 3D exercise (3DE) group performed 3D Air Balance exercise for 10 minutes after performing the pelvic stabilization exercise program for 40 minutes. [Results] The PSE group showed statistically significant differences in tape measure method (TMM) and maximum pressure between pre-test and post-test, and 3DE showed statistically significant differences in TMM, the difference in maximum pressure, the difference in average pressure, and the difference in support area. At the end of the 6-week intervention, TMM, difference in maximum pressure, difference in average pressure, and difference in support area showed significantly greater reduction in the 3DE group. [Conclusion] The results show that 3D stabilization exercise was more effective at improving the stabilization of the deep muscles surrounding the pelvis and left-right muscular balance. We consider that 3D exercise should be included in exercise programs for improving pelvic cavity and spinal stability in the future.

  14. Earth in the balance. Ecology and the human spirit; Urgence Planete Terre. L'esprit humain face a la crise ecologique

    Energy Technology Data Exchange (ETDEWEB)

    Al Gore

    2007-07-01

    This book is the translation of the original American edition 'earth in the balance'. When Earth in the Balance first came out, it caused quite a stir and for good reason. It convincingly makes the case that a crisis of epidemic proportions is nearly upon us and that if the world does not get its act together soon and agree to some kind of 'Global Marshall Plan' to protect the environment, we're all up a polluted creek without a paddle. Myriad plagues are upon us, but the worst include the loss of biodiversity, the depletion of the ozone layer, the slash-and-burn destruction of rain forests, and the onset of global warming. None of this is new, of course, nor was it new in 1992. But most environmentalists will still get a giddy feeling reading such a call to action as written by a prominent politician. The book is arranged into three sections: the first describes the plagues; the second looks at how we got ourselves into this mess; and the final chapters present ways out. Gore gets his points across in a serviceable way, though he could have benefited from a firmer editor's hand; at times the analogies are arcane and the pacing is odd kind of like a Gore speech that climaxes at weird points and then sinks just as the audience is about to clap. Still, at the end you understand what's been said. Gore believes that if we apply some American ingenuity, the twin engines of democracy and capitalism can be rigged to help us stabilize world population growth, spread social justice, boost education levels, create environmentally appropriate technologies, and negotiate international agreements to bring us back from the brink. For example, a worldwide shift to clean, renewable energy sources would create huge economic opportunities for companies large and small to design, build, and maintain solar panels, wind turbines, fuel cells, and other eco friendly innovations.

  15. Quantifying Uncertainty in the Predictions of the SimSphere Land Biosphere Model in Simulating Key Parameters Characterising Earth's Energy Balance

    Science.gov (United States)

    North, Matthew; Petropoulos, George

    2014-05-01

    Soil Vegetation Atmosphere Transfer (SVAT) models are becoming the preferred scientific tool to assess land surface energy fluxes due to their computational efficiency, accuracy and ability to provide results at fine temporal scales. An all-inclusive validation of those models is a fundamental step before those can be confidently used for any practical application or research purpose alike. SimSphere is an example of a SVAT model, simulating a large array of parameters characterising various land surface interactions over a 24 hour cycle at a 1-D vertical profile. Being able to appreciate the uncertainty of SimSphere predictions, is of vital importance towards increasing confidence in the models' overall use and ability to represent accurate land surface interactions. This is particularly important, given that its use either as a stand-alone tool or synergistically with Earth Observation (EO) data is currently expanding worldwide. In the present study, uncertainty in the SimSphere's predictions is evaluated at seven European sites, representative of a range of ecosystem conditions and biomes types for which in-situ data from the CarboEurope IP operational network acquired during 2011 were available. Selected sites are characterised by varying topographical characteristics, which further allow developing a comprehensive understanding on how topography can affect the models' ability to reproduce the variables which are evaluated. Model simulations are compared to in-situ data collected on cloud free days and on days with high Energy Balance Ratio. We focused here specifically on evaluating SimSphere capability in predicting selected variables of the energy balance, namely the Latent Heat (LE), Sensible heat (H) and Net Radiation (Rn) fluxes. An evaluation of the uncertainty in the model predictions was evaluated on the basis of extensive statistical analysis that was carried out by computing a series of relevant statistical measures. Results obtained confirmed the

  16. High-Pressure Rare Earth Disilicates REE2Si 2O 7( REE=Nd, Sm, Eu, Gd): Type K

    Science.gov (United States)

    Fleet, Michael E.; Liu, Xiaoyang

    2001-10-01

    A new structure type (K) is reported for the disilicates of Nd, Sm, Eu, and Gd made at high pressure. Crystals of type K were synthesized at 10 GPa, 1600-1700°C in an MA6/8 superpress and used for single-crystal X-ray structure study by Kappa CCD diffractometry at room temperature. Crystal data are: monoclinic, space group P21/n, Z=4; Nd2Si2O7-a=6.6658(2), b=6.7234(3), c=12.3975(6) Å, β=102.147(3)°, V=543.2 Å3, R=0.029, and Dx=5.584 g/cm3; Sm2Si2O7-a=6.6039(3), b=6.6849(3), c=12.3069(5) Å, β=102.489(3)°, V=530.4 Å3, R=0.038, and Dx=5.871 g/cm3; Eu2Si2O7-a=6.5777(3), b=6.6652(4), c=12.2668(8) Å, β=102.671(4)°, V=524.7 Å3, R=0.030, and Dx=5.976 g/cm3; Gd2Si2O7-a=6.5558(4), b=6.6469(4), c=12.2394(6) Å, β=102.844(3)°, V=520.0 Å3, R=0.026, and Dx=6.166 g/cm3. The type K structure is built from a diorthosilicate group [Si2O7] interconnected by REE3+ cations in eightfold coordination with oxygen. The bridging oxygen (Si-O-Si) bond angle of the diorthosilicate group of rare earth disilicates stable at 1 bar (types A to G) is related to spatial accommodation of the REE3+ cation and ranges from 130 to 135° in the light rare earth disilicates (types A, F, G) to 180° in Lu2Si2O7 (type C). Volume reduction in the high-pressure type K structure is achieved largely by closure of the Si-O-Si bond angle to 122.7-124.4°, through rigid body rotation of the two SiO4 tetrahedra. This also permits a marginal increase in the average coordination of the REE3+ cation.

  17. Effects of supplementing rare earth element cerium on rumen fermentation, nutrient digestibility, nitrogen balance and plasma biochemical parameters in beef cattle.

    Science.gov (United States)

    Lin, S X; Wei, C; Zhao, G Y; Zhang, T T; Yang, K

    2015-12-01

    The objectives of the trial were to investigate the effects of supplementing rare earth element (REE) cerium (Ce) on rumen fermentation, nutrient digestibility, methane (CH4 ) production, nitrogen (N) balance and plasma biochemical parameters in beef cattle. Four Simmental male cattle, aged at 14 months, with initial liveweight of 355 ± 8 kg and fitted with permanent rumen cannulas, were used as experimental animals. The cattle were fed with a total mixed ration (TMR) composed of concentrate mixture and corn silage. Four levels of cerium chloride (CeCl3 ·7H2 O, purity 99.9%), that is 0, 80, 160 and 240 mg CeCl3 /kg DM, were added to basal ration in a 4 × 4 Latin square design. Each experimental period lasted 15 days, of which the first 12 days were for pre-treatment and the last 3 days were for sampling. The results showed that supplementing CeCl3 at 160 or 240 mg/kg DM increased neutral detergent fibre (NDF) digestibility (p cattle increased the digestibility of NDF, decreased the molar ratio of rumen acetate to propionate, increased N retention and microbial N flow and decreased CH4 /kg DMI.

  18. Experimental study on thermal-hydraulic behaviors of a pressure balanced coolant injection system for a passive safety light water reactor JPSR

    Energy Technology Data Exchange (ETDEWEB)

    Satoh, Takashi; Watanabe, Hironori; Araya, Fumimasa; Nakajima, Katsutoshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Iwamura, Takamichi; Murao, Yoshio

    1998-02-01

    A conceptual design study of a passive safety light water reactor JPSR has been performed at Japan Atomic Energy Research Institute JAERI. A pressure balanced coolant injection experiment has been carried out, with an objective to understand thermal-hydraulic characteristics of a passive coolant injection system which has been considered to be adopted to JPSR. This report summarizes experimental results and data recorded in experiment run performed in FY. 1993 and 1994. Preliminary experiments previously performed are also briefly described. As the results of the experiment, it was found that an initiation of coolant injection was delayed with increase in a subcooling in the pressure balance line. By inserting a separation device which divides the inside of core make-up tank (CMT) into several small compartments, a diffusion of a high temperature region formed just under the water surface was restrained and then a steam condensation was suppressed. A time interval from an uncovery of the pressure balance line to the initiation of the coolant injection was not related by a linear function with a discharge flow rate simulating a loss-of-coolant accident (LOCA) condition. The coolant was injected intermittently by actuation of a trial fabricated passive valve actuated by pressure difference for the present experiment. It was also found that the trial passive valve had difficulties in setting an actuation set point and vibrations noises and some fraction of the coolant was remained in CMT without effective use. A modification was proposed for resolving these problems by introducing an anti-closing mechanism. (author)

  19. 非极限状态挡土墙主动土压力研究%Active earth pressure on retaining wall under non-limit state

    Institute of Scientific and Technical Information of China (English)

    胡俊强; 张永兴; 陈林; 陈建功

    2013-01-01

    The thin layer element method is used to study the active earth pressure under non-limit state. It is considered that the earth pressure against the back of a retaining wall is due to the thrust exerted by a sliding wedge of the soil between the back of the wall and a plane which passes through the bottom edge of the wall. The basic equations are proposed by considering the equilibrium of the forces and moments on a thin-layer element of the wedge. By using the equilibrium equations, the coefficients of earth pressure, the unit earth pressure, the resultant force of earth pressure and the acting point of the resultant force are obtained. The effects of the internal frictional angle of backfill, the frictional angle between the wall and the backfill and the displacement ratio of the wall on the lateral coefficient of earth pressure, the earth pressure, the resultant force of earth pressure, the acting point of the resultant force are investigated. The discussions indicate that if they are designed according to the limit equilibrium theory, it will be dangerous for the overturning stability of retaining walls with the active translational movement mode under non-limit state. Moreover, the distributions of the active earth pressure computed by the deduced formula agree with the measured data of the engineering case well.%利用薄层单元法对挡土墙非极限状态主动土压力进行研究,认为挡土墙土压力是由墙后填土在平衡状态下出现的楔形土体产生,取挡土墙后楔形土体沿平行于填料坡面的薄层作为微分单元体,通过作用在微分单元体的力和力矩平衡条件,建立挡土墙非极限状态主动土压力微分方程,得到非极限状态土侧压力系数、土压力强度、土压力合力和作用点的理论公式.根据非极限状态摩擦角与墙体位移关系,分析填土内摩擦角、墙土摩擦角和挡土墙位移比对土侧压力系数、土压力分布、土压力系数和作用点的影

  20. In situ XFEL measurement system for Earth and planetary materials under laser-induced ultrahigh-pressure conditions

    Science.gov (United States)

    Tange, Y.; Ozaki, N.; Matsuoka, T.; Ogawa, T.; Albertazzi, B.; Habara, H.; Takahashi, K.; Matsuyama, S.; Yamauchi, K.; Tanaka, K.; Kodama, R.; Sato, T.; Sekine, T.; Seto, Y.; Okuchi, T.; Yabuuchi, T.; Inubushi, Y.; Yabashi, M.

    2015-12-01

    High-pressure and high-temperature in situ experiments have revealed behaviors of the earth and planetary constituents under extreme conditions, and contribute to progress our understandings about physical and chemical structure of planetary interiors. These in situ techniques have developed with the third-generation synchrotron radiation facilities such as APS, ESRF, and SPring-8 mainly using large volume presses and diamond anvil cells. In addition to the synchrotron light source, recently X-ray free electron laser (XFEL) facilities have been developed as LCLS and SACLA. The brilliant and extremely short-pulsed XFELs make it possible to carry out femto-second time-resolve measurements, and to observe materials under dynamic/shock compression clearly. Techniques using high-power laser and XFEL are expected to be a next-generation experimental platform, and a pump-probe measurement system using high-power lasers and XFEL was installed at BL3EH5 in SPring-8/SACLA interoperable experimental facility. The system is composed of 45 TW X-ray focusing system (KB mirrors), vacuumed sample chamber, and the MPCCD detector developed for the 10-fs ultra-short pulsed XFEL light source. The high-power laser enables us to generate up to 100 GPa for metal, simple oxide, and natural/synthesized mineral samples. Samples are mounted on sample holders and aligned at the center of the vacuum chamber using a 4-axis Goniometer head. In this presentation, we will overview the experimental setups and typical results of current pump-probe system using XFEL in SACLA.

  1. Active earth pressure on retaining walls in non-limit state%挡土墙非极限状态主动土压力分布

    Institute of Scientific and Technical Information of China (English)

    张永兴; 陈林

    2011-01-01

    The Coulomb's limit equilibrium theory is modified to study the active earth pressure on retaining walls in non-limit state. It is considered that the earth pressure on a retaining wall is due to the thrust of a sliding wedge of soil between the back of the wall and a plane which passes through the bottom edge of the wall. The basic equations are formulated by considering the equilibrium of the forces on a thin-layer element of the wedge. By using the equilibrium equations of the moments on the entire wedge, the lateral coefficient of earth pressure, the earth pressure distribution along the wall back, the resultant force of earth pressure and its action point are obtained. The effects of the internal frictional angle of the backfill, the frictional angle between the wall and the backfill and the displacement ratio of the wall on the lateral coefficient of earth pressure, the earth pressure, the resultant force of earth pressure and its action point,and the overturning stability of the retaining wall are investigated. The proposed method is compared with experimental data. Evaluation of the influence of the displacement ratio of the wall on the overturning moment indicates that if they are designed according to the limit equilibrium theory, it would be dangerous for the overturning stability of the retaining wall with an active translational movement in non-limit state.%改进库仑极限平衡理论,用于非极限状态主动土压力的研究,认为挡土墙土压力是由墙后填土在平衡状态下出现的滑动楔体所产生.在该滑动楔体上沿竖向取水平薄层作为微分单元体,通过作用在单元体上力的平衡条件,建立挡土墙非极限状态主动土压力基本方程,并结合整个滑楔体的力矩平衡条件,由此得到对应不同内摩擦角、墙土摩擦角和挡土墙位移比的侧土压力系数,将其用于水平微分单元法求解刚性挡土墙平移模式下非极限状态主动土压力,得到挡土墙土压

  2. 各向异性砂土主动侧土压力计算方法%Evaluation of earth pressure at active side for anisotropic sand

    Institute of Scientific and Technical Information of China (English)

    宋飞; 张建民

    2011-01-01

    Evaluation of earth pressure is one of the key research subjects in soil mechanics and geotechnical engineering.The backfill displays anisotropic mechanical characteristics because of compaction in engineering practice; it is always at the non-limit state between the active and passive states.Classic Rankine and Coulomb earth pressure theories do not consider the effea of anisotropy and backfill deformation on the earth pressure.Based on a series of constant strain increment ratio tests, the unique relation between the earth pressure coefficient and the lateral strain constraint is established for anisotropic sand.On this basis.a method is proposed for estimating the earth pressure at the active side for anisotropic backfill sand under translational wall movement mode; and corresponding formulas are derived.Besides, the effectiveness of the suggested method is confirmed experimentally.%土压力是土力学和岩土工程领域的基本研究课题之一.由于碾压作用墙后填土具有不同程度的各向异性,并且通常处于主动与被动状态之间的非极限状态.经典的朗肯和库仑土压力理论没有考虑填土各向异性的力学性质及挡墙位移效应对于土压力的影响.基于各向异性砂土的等应变增量比系列试验结果建立了土压力系数与与用应变增量比表述的应变约束条件之间所具有的惟一性关系,在此基础上给出了平动位移模式下各向异性砂土的主动土压力计算方法,并通过土压力离心模型试验结果对其计算方法进行了验证,初步表明了其有效性和合理性.

  3. 变频均压防灭火控制系统的设计%System of Air Pressure Balance for Fire Control Based on Frequency Converter

    Institute of Scientific and Technical Information of China (English)

    蒋德智

    2013-01-01

      本文介绍了基于变频调速技术的矿井局扇风机控制系统的设计,该系统根据均压通风原理,通过传感器测量巷道进出风速、进风风门内外压差、一氧化碳浓等物理量,进行PID运算,调节变频器输出频率从而调节风机转速,实现风压和风量的动态平衡控制,在满足工作面正常通风的前提下,最大程度地减小采空区的漏风量,从而达到防灭火的目的。同时系统具有一氧化碳报警功能,当工作面发生起火现象时能够及时报警并采取相应的通风策略,减小或避免煤矿井下发生火险的可能性。%In this paper we introduced a design of pressure balance for air control system based on variable-frequency driver.This system is designed according to pressure balance for air theory,adjust the output frequency of VFD to regulate the motor speed,so we can realize the dynamic balance control of the air pressure and air quantity.The PID operation is based on the value of the wind speed sensor,air pressure sensor,CO concentration sensor.Under the premise of normal wind providing,we can reduce the catching fire possibility of mined-out area.Simultaneously,the system possesses the function of CO alarm,when the mined-out area is catching fire,system can generate a warning sign and take proper ventilation measure.

  4. Earth materials and earth dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Bennett, K; Shankland, T. [and others

    2000-11-01

    In the project ''Earth Materials and Earth Dynamics'' we linked fundamental and exploratory, experimental, theoretical, and computational research programs to shed light on the current and past states of the dynamic Earth. Our objective was to combine different geological, geochemical, geophysical, and materials science analyses with numerical techniques to illuminate active processes in the Earth. These processes include fluid-rock interactions that form and modify the lithosphere, non-linear wave attenuations in rocks that drive plate tectonics and perturb the earth's surface, dynamic recrystallization of olivine that deforms the upper mantle, development of texture in high-pressure olivine polymorphs that create anisotropic velocity regions in the convecting upper mantle and transition zone, and the intense chemical reactions between the mantle and core. We measured physical properties such as texture and nonlinear elasticity, equation of states at simultaneous pressures and temperatures, magnetic spins and bonding, chemical permeability, and thermal-chemical feedback to better characterize earth materials. We artificially generated seismic waves, numerically modeled fluid flow and transport in rock systems and modified polycrystal plasticity theory to interpret measured physical properties and integrate them into our understanding of the Earth. This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL).

  5. Temperature of Earth's Deep Interior Constrained from Melting of Fe and Fe0.9Ni0.1 at High Pressures

    Science.gov (United States)

    Zhang, D.; Jackson, J. M.; Zhao, J.; Sturhahn, W.; Alp, E. E.; Hu, M. Y.; Toellner, T.; Murphy, C. A.; Prakapenka, V.

    2015-12-01

    The melting points of fcc- and hcp-structured Fe0.9Ni0.1 and Fe have been measured up to Mbar pressure. We use laser heated diamond anvil cells, time-resolved synchrotron Mössbauer spectroscopy, x-ray diffraction and a recently developed fast temperature readout spectrometer to carry out these measurements. X-ray photons at 57Fe's resonant energy with 1 meV bandwidth are focused on the sample in a laser heated diamond anvil cell, and when melting occurs, the characteristic Mössbauer signal abruptly decreases. Thus, time-resolved Mössbauer spectroscopy provides an excellent diagnostic for the first melt formed in the sample chamber. The thermal contributions of pressure of Fe0.9Ni0.1 and Fe have been constrained by combining nuclear resonant inelastic scattering and high temperature X-ray diffraction measurements. We find that the melting curve of Fe is systematically higher than the melting curve of Fe0.9Ni0.1, while the 1-σ temperature uncertainties of both melting curves overlap. The pressure dependencies of the melting temperature of fcc-structured Fe and Fe0.9Ni0.1 are measured, and the best-fit melting curves are located in the region bounded by previous studies. Our results may help reach a consensus on the high pressure melting curves of Fe and Fe-Ni alloys. We calculate the fcc-hcp-liquid triple points of Fe0.9Ni0.1and Fe, complemented by experiments with Mössbauer spectroscopy. The upper bound of Earth's inner core-outer core boundary temperature is estimated from our results, and the upper bound of the temperature at Earth's core-mantle boundary is computed with an adiabatic model. We discuss the implications of these temperatures on the phase relations of deep Earth materials. References:Murphy, C.A., J.M. Jackson, W. Sturhahn, and B. Chen (2011): Melting and thermal pressure of hcp-Fe from the phonon density of states, Phys. Earth Planet. Int., 188, 114-120 Jackson, J.M., W. Sturhahn, M. Lerche, J. Zhao, T.S. Toellner, E.E. Alp, S.V. Sinogeikin, J

  6. Repeatability of frequency of corrective foot pressure during balance control in children aged between 2 and 7.

    Science.gov (United States)

    Sobera, Małgorzata; Siedlecka, Bożena

    2010-01-01

    The frequency of corrective signal (the centre of corrective (COC) signal), which is the decomposition of COP (centre of pressure) and estimated COM (centre of mass) time series, is one of the indicators reflecting the quality of postural control during stance. Young children, in the period of intensive development, gradually improve the quality of postural control in a daily life. The purpose of this paper was to describe the time series of corrective centre of foot pressure repeatability in young children aged between 2 and 7 during body stability in natural stance position. 272 healthy children aged between 2 and 7 were divided into 6 age groups. Two AccuSway force platforms were used (one foot of the subject was on one platform, the second foot, on the other). The COP trajectories were the basis for the calculation of the frequency stability indices in frontal and sagittal planes for the left leg and right leg separately. The COC signals were collected by the method based on the Kuczyński viscoelastic model. In order to assess the repeatability, the concordance correlation coefficient (CCC) was used between the 1st and the 2nd trials, the 2nd and the 3rd trials, and the 1st and the 3rd trials. The maturation of postural control system goes rather slowly in two youngest groups which showed the poor repeatability in COC frequency between the 2nd and the 3rd years of life. From the 4th to the 7th year of life the inter-session repeatability rapidly increases in three consecutive trials. Poor difference of frequency concordance was found between the left and right lower limbs. It is concluded that the frequency of corrective foot pressure is the reliable indicator of postural control for children aged between 4 and 7, but not for younger ones.

  7. UNIFIED METHOD OF SEPARATE AND COMBINED CALCULATION OF WATER AND EARTH PRESSURES%水土压力分算与合算的统一算法

    Institute of Scientific and Technical Information of China (English)

    王洪新

    2011-01-01

    Applying combined calculation of water and earth pressures for clay leads to a result which is more close to the field measurement value, however, obviously violates the principle of effective stress. Based on characteristics of the pore water in soil, it is assumed that the bound water absorbed by the clay particles in the soil offsets part of soil pore, and finally physical parameters such as void ratio, boundary water content, particle analysis, etc. are introduced to calculation of water and earth pressures on retaining structures to propose a coefficient ξ which can be calculated through physical parameters of soil and to provide the method of measuring the value of ξ through permeability tests. With the coefficient ξ, the effective stress intensity index and total stress intensity index are integrated in one strength formula. A new calculation method to unify the separate calculation and combined calculation of water and earth pressures is proposed to carry out the transition between results of the two conventional calculation methods and provide a new idea for solving the jump problem between the two results. According to the theory analysis of this paper, the measured permeability coefficient-void ratio curve will have a translational move in a forward direction along e-axis. The more clay particles that soil contains will have the larger translation, which has been verified by experimental data of related literatures. Separate calculation of water and earth pressures is too conventional for sand soil containing clay particles while combined calculation of water and earth pressures for clay with high void ratio can't guarantee the safety. Water and earth pressures on retaining structure are related not only to the soil categories, but also the void ratio.%以土中孔隙水特征为基础,假定土体中的黏性土颗粒吸附的结合水会抵消一部分土中孔隙,最终把土的孔隙比、界限含水量、颗粒分析等物理参数引入土水

  8. Programming blood pressure in adult SHR by shifting perinatal balance of NO and reactive oxygen species toward NO: the inverted Barker phenomenon.

    Science.gov (United States)

    Racasan, Simona; Braam, Branko; Koomans, Hein A; Joles, Jaap A

    2005-04-01

    The "programming hypothesis" proposes that an adverse perinatal milieu leads to adaptation that translates into cardiovascular disease in adulthood. The balance between nitric oxide (NO) and reactive oxygen species (ROS) is disturbed in cardiovascular diseases, including hypertension. Conceivably, this balance is also disturbed in pregnancy, altering the fetal environment; however, effects of perinatal manipulation of NO and ROS on adult blood pressure (BP) are unknown. In spontaneously hypertensive rats (SHR), NO availability is decreased and ROS are increased compared with normotensive Wistar-Kyoto rats, and, despite the genetic predisposition, the perinatal environment can modulate adult BP. Our hypothesis is that a disturbed NO-ROS balance in the SHR dam persistently affects BP in her offspring. Dietary supplements, which support NO formation and scavenge ROS, administered during pregnancy and lactation resulted in persistently lower BP for up to 48 wk in SHR offspring. The NO donor molsidomine and the superoxide dismutase mimic tempol-induced comparable effects. Specific inhibition of inducible nitric oxide synthase (NOS) reduces BP in adult SHR, suggesting that inducible NOS is predominantly a source of ROS in SHR. Indeed, inducible NOS inhibition in SHR dams persistently reduced BP in adult offspring. Persistent reductions in BP were accompanied by prevention of proteinuria in aged SHR. We propose that in SHR the known increase in ANG II type 1 receptor density during development leads to superoxide production, which enhances inducible NOS activity. The relative shortage of substrate and cofactors leads to uncoupling of inducible NOS, resulting in superoxide production, activating transcription factors that subsequently again increase inducible NOS expression. This vicious circle probably is perpetuated into adult life.

  9. Education and Outreach Programs Offered by the Center for High Pressure Research and the Consortium for Materials Properties Research in Earth Sciences

    Science.gov (United States)

    Richard, G. A.

    2003-12-01

    Major research facilities and organizations provide an effective venue for developing partnerships with educational organizations in order to offer a wide variety of educational programs, because they constitute a base where the culture of scientific investigation can flourish. The Consortium for Materials Properties Research in Earth Sciences (COMPRES) conducts education and outreach programs through the Earth Science Educational Resource Center (ESERC), in partnership with other groups that offer research and education programs. ESERC initiated its development of education programs in 1994 under the administration of the Center for High Pressure Research (CHiPR), which was funded as a National Science Foundation Science and Technology Center from 1991 to 2002. Programs developed during ESERC's association with CHiPR and COMPRES have targeted a wide range of audiences, including pre-K, K-12 students and teachers, undergraduates, and graduate students. Since 1995, ESERC has offered inquiry-based programs to Project WISE (Women in Science and Engineering) students at a high school and undergraduate level. Activities have included projects that investigated earthquakes, high pressure mineral physics, and local geology. Through a practicum known as Project Java, undergraduate computer science students have developed interactive instructional tools for several of these activities. For K-12 teachers, a course on Long Island geology is offered each fall, which includes an examination of the role that processes in the Earth's interior have played in the geologic history of the region. ESERC has worked with Stony Brook's Department of Geosciences faculty to offer courses on natural hazards, computer modeling, and field geology to undergraduate students, and on computer programming for graduate students. Each summer, a four-week residential college-level environmental geology course is offered to rising tenth graders from the Brentwood, New York schools in partnership with

  10. Analysis on Influencing Factors of the Actual Earth Pressure of Foundation Pit%基坑真实土压力的影响因素分析

    Institute of Scientific and Technical Information of China (English)

    宋明健; 杨庆; 钟义敏

    2011-01-01

    Accurate earth pressure is the key factor to ensure the safety and stability of foundation pit.Combined with the recent research progress in foundation pit engineering,various influencing factors of the actual earth pressure are analyzed and described,and the awareness of these factors in the current design construction is summarized in this paper.Based on this,this paper also puts forward some suggestions on acquiring the actual earth pressure,such as to master accurate environmental and geotechnical information,strengthen studies on calculation method and space-time coupling theory,establish regional geotechnical information management system,adopt dynamic design based on back analysis,and use dynamic supporting technology closed integrated with monitoring information.%土压力的准确分析是确保基坑安全稳定的关键。结合基坑工程的最新研究进展,对真实土压力的诸多影响因素进行了分析和论述,并简要归纳了目前设计施工中对这些影响因素的认识现状。在此基础上,提出了把握真实土压力的一些建议:准确掌握环境岩土信息;加强计算方法、时空耦合效应等理论的研究;建立区域岩土信息管理系统;采用以反分析为基础的动态设计;使用与监测信息密切结合的动态支护技术等。

  11. 挡土墙被动土压力的滑移线解%Slip-line solution to passive earth pressure on retaining walls

    Institute of Scientific and Technical Information of China (English)

    彭明祥

    2011-01-01

    Based on the limit equilibrium theory, the backfill is treated as a perfectly elastic-plastic material which follows the Mohr-Coulomb yield criterion, and is assumed to be an isotropic, homogeneous and incompressible (or non-expansive) perfectly continuous medium.The stress singularity and its stress boundary condition are introduced, and' a statically determinate and solvable mathematical model for the limit equilibrium boundary value problem is established without considering the stress-strain relationship.Then the slip-line field and stress field in plastic zone of the backfill are solved by use of the slip-line method, furthermore, the passive earth pressure on retaining walls and the reaction on slip surfaces are derived.Geometric and mechanical similarity principle is presented by means of dimensionless analysis.The results show that the slip-line solution to the passive earth pressure is generally less than or equal to the Coulomb's solution, and the classical Rankine's earth pressure or the classical Coulomb's earth pressure satisfying non-singularity condition is in accordance with the slip-line solution, and the Hencky's first theorem and second theorem are not generally applicable.%基于极限平衡理论,视墙后填土为服从Mohr-Coulomb屈服准则的理想弹塑性材料,并且假定它是各向同性的、均匀的以及不可压缩(膨胀)的理想连续介质.引进了应力奇点及其应力边界条件,建立了静定可解的极限平衡边值问题数学模型,而不必考虑土的应力-应变关系,采用滑移线法求解了墙后塑性区的滑移线场和应力场,进而求解了挡土墙被动土压力和滑裂面土反力.通过无量纲分析,提出了几何力学相似原理.数值分析表明,被动土压力的滑移线解一般总是小于或等于库仑解,经典朗肯土压力或满足非奇异条件的经典库仑土压力与滑移线解一致,Hencky第一定理和第二定理不具有普遍适用性.

  12. Universal behavior of chalcogenides of rare-earth metals in the transition to a state with intermediate valence at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Tsiok, O. B.; Khvostantsev, L. G.; Brazhkin, V. V., E-mail: brazhkin@hppi.troitsk.ru [Russian Academy of Sciences, Vereshchagin Institute of High-Pressure Physics (Russian Federation)

    2015-06-15

    Precision measurements of resistivity, thermopower, and volume are performed for TmS, TmSe, and TmTe under a hydrostatic pressure up to 8 GPa. Comparison of the transport properties and volume of TmTe and SmTe in the valence transition region demonstrates a complete analogy up to quantitative coincidence. It is shown that the thermopower of all thulium and samarium chalcogenides in the lattice collapse region and in subsequent rearrangement of the electron spectrum in a wide range of pressures follow a universal dependence corresponding the passage of the Fermi level through the peak of the density of states (DOS). The results are considered in the context of ideas about the exciton nature of the intermediate valence in chalcogenides of rare-earth metals.

  13. Magnesite formation from MgO and CO2 at the pressures and temperatures of Earth's mantle

    Energy Technology Data Exchange (ETDEWEB)

    Scott, Henry P.; Doczy, Vincent M.; Frank, Mark R.; Hasan, Maggie; Lin, Jung-Fu; Yang, Jing [NIU; (Indiana); (Texas)

    2013-08-02

    Magnesite (MgCO3) is an important phase for the carbon cycle in and out of the Earth’s mantle. Its comparably large P-T stability has been inferred for several years based on the absence of its decomposition in experiments. Here we report the first experimental evidence for synthesis of magnesite out of its oxide components (MgO and CO2) at P-T conditions relevant to the Earth’s mantle. Magnesite formation was observed in situ using synchrotron X-ray diffraction, coupled with laser-heated diamond-anvil cells (DACs), at pressures and temperatures of Earth’s mantle. Despite the existence of multiple high-pressure CO2 polymorphs, the magnesite-forming reaction was observed to proceed at pressures ranging from 5 to 40 GPa and temperatures between 1400 and 1800 K. No other pressure-quenchable materials were observed to form via the MgO + CO2 = MgCO3 reaction. This work further strengthens the notion that magnesite may indeed be the primary host phase for oxidized carbon in the deep Earth.

  14. Determination of calcium carbonate and sodium carbonate melting curves up to Earth's transition zone pressures with implications for the deep carbon cycle

    Science.gov (United States)

    Li, Zeyu; Li, Jie; Lange, Rebecca; Liu, Jiachao; Militzer, Burkhard

    2017-01-01

    Melting of carbonated eclogite or peridotite in the mantle influences the Earth's deep volatile cycles and bears on the long-term evolution of the atmosphere. Existing data on the melting curves of calcium carbonate (CaCO3) and sodium carbonate (Na2CO3) are limited to 7 GPa and therefore do not allow a full understanding of carbon storage and cycling in deep Earth. We determined the melting curves of CaCO3 and Na2CO3 to the pressures of Earth's transition zone using a multi-anvil apparatus. Melting was detected in situ by monitoring a steep and large increase in ionic conductivity, or inferred from sunken platinum markers in recovered samples. The melting point of CaCO3 rises from 1870 K at 3 GPa to ∼2000 K at 6 GPa and then stays within 50 K of 2000 K between 6 and 21 GPa. In contrast, the melting point of Na2CO3 increases continuously from ∼1123 K at 3 GPa to ∼1950 K at 17 GPa. A pre-melting peak in the alternating current through solid CaCO3 is attributed to the transition from aragonite to calcite V. Accordingly the calcite V-aragonite-liquid invariant point is placed at 13 ± 1 GPa and 1970 ± 40 K, with the Clapeyron slope of the calcite V to aragonite transition constrained at ∼70 K/GPa. The experiments on CaCO3 suggest a slight decrease in the melting temperature from 8 to 13 GPa, followed by a slight increase from 14 to 21 GPa. The negative melting slope is consistent with the prediction from our ab initio simulations that the liquid may be more compressible and become denser than calcite V at sufficiently high pressure. The positive melting slope at higher pressures is supported by the ab initio prediction that aragonite is denser than the liquid at pressures up to 30 GPa. At transition zone pressures the melting points of CaCO3 are comparable to that of Na2CO3 but nearly 400 K and 500 K lower than that of MgCO3. The fusible nature of compressed CaCO3 may be partially responsible for the majority of carbonatitic melts found on Earth's surface

  15. Repetitive sit-to-stand training with the step-foot position on the non-paretic side, and its effects on the balance and foot pressure of chronic stroke subjects.

    Science.gov (United States)

    Kim, Kyung; Kim, Young Mi; Kang, Dong Yeon

    2015-08-01

    [Purpose] This study aimed to improve the asymmetrical weight-bearing ratio by applying repetitive sit-to-stand training methods that feature a step-foot position to the paretic-side foot of hemiplegic patients; it sought also to provide the information needed to apply weight-bearing and balance training to hemiplegic patients. [Subjects and Methods] The subjects were divided into two groups: a spontaneous group and a step group. They all performed repetitive sit-to-stand training five times per week for a total of six weeks. The Biodex Balance System, TUG, and 5XSST were used to measure the static and dynamic standing balance of each patient. A foot mat system was used to measure foot pressure. [Results] In the balance measurements, differences in the Overall index, Ant-post index, Med-lat index, Fall risk index, TUG, and 5XSST after training was significantly different between the two study groups. In evaluating foot pressure measurements, we found that the COP (Ant-post), Peak pressure: hind foot, and Contact area: hind foot measurements significantly differed between the groups after the training. [Conclusion] Repetitive sit-to-stand training that involves positioning the non-paretic leg upward can be considered a significant form of training that improves the symmetric posture adjustment and balance of hemiplegic patients following a stroke.

  16. 溧阳抽水蓄能电站主体工程土石方调配平衡研究%Study on allocation balance of earth-rock work for main works of Liyang Pumped Storage Hydropower Station

    Institute of Scientific and Technical Information of China (English)

    肖浩; 申明亮; 张文熙; 任亮

    2011-01-01

    针对溧阳抽水蓄能电站工程C1标、C2标的施工方案,较全面系统地分析了土石方施工工程中的影响因素,以及各个方面相互联系和制约关系,进行了土石方调配平衡系统与道路运输系统等的综合优化,以寻求合理的土石方调配方案,达到快速、合理、经济施工之目的.%In allusion to the construction schemes of the bid-sections of C1 and C2 of the construction of Liyang Pumped Storage Hydropower Station, the impact factors from the construction of the earth-rock work are systematically analyzed herein along with the study on the mutually associated and restricted relationships at all the aspects concerned, and then the comprehensive optimizations are made on both the balancing system for the allocation of the earth-rock work and the road transportation system, so as to obtain a reasonable earth-rock work allocation scheme and get the target of quick, reasonable and economic construction.

  17. Atomistic and Ab initio modeling of CaAl2O4 high-pressure polymorphs under Earth's mantle conditions

    Science.gov (United States)

    Eremin, N. N.; Grechanovsky, A. E.; Marchenko, E. I.

    2016-05-01

    Semi-empirical and ab initio theoretical investigation of crystal structure geometry, interatomic distances, phase densities and elastic properties for some CaAl2O4 phases under pressures up to 200 GPa was performed. Two independent simulation methods predicted the appearance of a still unknown super-dense CaAl2O4 modification. In this structure, the Al coordination polyhedron might be described as distorted one with seven vertices. Ca atoms were situated inside polyhedra with ten vertices and Ca-O distances from 1.96 to 2.49 Å. It became the densest modification under pressures of 170 GPa (density functional theory prediction) or 150 GPa (semi-empirical prediction). Both approaches indicated that this super-dense CaAl2O4 modification with a "stuffed α-PbO2" type structure could be a probable candidate for mutual accumulation of Ca and Al in the lower mantle. The existence of this phase can be verified experimentally using high pressure techniques.

  18. SPES-2, AP600 intergral system test S01007 2 inch CL to core make-up tank pressure balance line break

    Energy Technology Data Exchange (ETDEWEB)

    Bacchiani, M.; Medich, C.; Rigamonti, M. [SIET S.p.A. Piacenza (Italy)] [and others

    1995-09-01

    The SPES-2 is a full height, full pressure experimental test facility reproducing the Westinghouse AP600 reactor with a scaling factor of 1/395. The experimental plant, designed and operated by SIET in Piacenza, consists of a full simulation of the AP600 primary core cooling system including all the passive and active safety systems. In 1992, Westinghouse, in cooperation with ENEL (Ente Nazionale per l` Energia Elettrica), ENEA (Enter per le numove Technlogie, l` Energia e l` Ambient), Siet (Societa Informazioni Esperienze Termoidraulich) and ANSALDO developed an experimental program to test the integrated behaviour of the AP600 passive safety systems. The SPES-2 test matrix, concluded in November 1994, has examined the AP600 passive safety system response for a range of small break LOCAs at different locations on the primary system and on the passive system lines; single steam generator tube ruptures with passive and active safety systems and a main steam line break transient to demonstrate the boration capability of passive safety systems for rapid cooldown. Each of the tests has provided detailed experimental results for verification of the capability of the analysis methods to predict the integrated passive safety system behaviour. Cold and hot shakedown tests have been performed on the facility to check the characteristics of the plant before starting the experimental campaign. The paper first presents a description of the SPES-2 test facility then the main results of S01007 test {open_quotes}2{close_quotes} Cold Leg (CL) to Core Make-up Tank (CMT) pressure balance line break{close_quotes} are reported and compared with predictions performed using RELAP5/mod3/80 obtained by ANSALDO through agreement with U.S.N.R.C. (U.S. Nuclear Regulatory Commission). The SPES-2 nodalization and all the calculations here presented were performed by ANSALDO and sponsored by ENEL as a part of pre-test predictions for SPES-2.

  19. Balance Problems

    Science.gov (United States)

    ... you are having balance problems, see your doctor. Balance disorders can be signs of other health problems, such ... cases, treating the illness that is causing the disorder will help with the balance problem. Exercises, a change in diet, and some ...

  20. RESEARCH ON ACTIVE EARTH PRESSURE BEHIND RIGID RETAINING WALL FROM CLAYEY BACKFILL CONSIDERING SOIL ARCHING EFFECTS%考虑土拱效应的黏性填土挡土墙主动土压力研究

    Institute of Scientific and Technical Information of China (English)

    涂兵雄; 贾金青

    2012-01-01

    Analytical expressions for the active earth pressure ratio and active earth pressure are derived, against on a rigid retaining wall from clayey backfill undergoing horizontal translation) considering the soil arching effects and the influence of soil-wall friction angle, wall adhesion and cohesion of backfill. The results show that the active earth pressure ratio and active earth pressure are related to soil-wall friction angle, depth of the point and the internal friction angle, cohesion, unit weight of the backfill. The theoretical comparisons between the analytical expressions proposed for active earth pressure ratio and active earth pressure and the existing classical theory, the previous research results show great agreement with each other, so as to verity the correctness of the results in this paper.%以墙后填土为黏性土的刚性挡土墙为研究对象,考虑挡土墙后的土拱效应,以及墙土摩擦角、墙土黏结力、墙后填土黏聚力的影响,推导挡土墙在平动模式下的主动土压力系数和主动土压力解析解.结果表明,考虑土拱效应的主动土压力系数和主动土压力均与墙土摩擦角、计算点深度以及墙后填土的内摩擦角、黏聚力及重度有关.通过将求解的主动土压力系数和主动土压力与现有经典理论解及前人理论研究成果对比,发现结果完全吻合,验证该研究结果的正确性.

  1. 3-D force-balanced magnetospheric configurations

    Directory of Open Access Journals (Sweden)

    S. Zaharia

    2004-01-01

    Full Text Available The knowledge of plasma pressure is essential for many physics applications in the magnetosphere, such as computing magnetospheric currents and deriving mag-netosphere-ionosphere coupling. A thorough knowledge of the 3-D pressure distribution has, however, eluded the community, as most in situ pressure observations are either in the ionosphere or the equatorial region of the magnetosphere. With the assumption of pressure isotropy there have been attempts to obtain the pressure at different locations,by either (a mapping observed data (e.g. in the ionosphere along the field lines of an empirical magnetospheric field model, or (b computing a pressure profile in the equatorial plane (in 2-D or along the Sun-Earth axis (in 1-D that is in force balance with the magnetic stresses of an empirical model. However, the pressure distributions obtained through these methods are not in force balance with the empirical magnetic field at all locations. In order to find a global 3-D plasma pressure distribution in force balance with the magnetospheric magnetic field, we have developed the MAG-3-D code that solves the 3-D force balance equation ${vec J} times {vec B} = nabla P$ computationally. Our calculation is performed in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials as ${vec B} = nabla psi times nabla alpha$. The pressure distribution, $P = P(psi, alpha$, is prescribed in the equatorial plane and is based on satellite measurements. In addition, computational boundary conditions for ψ surfaces are imposed using empirical field models

  2. Potassium-bearing Iron-Nickel Sulfides in Nature and High-Pressure Experiments: Geochemical Consequences of Potassium in the Earth's Core

    Science.gov (United States)

    Keshav, S.; Corgne, A.; McDonough, W. F.; Fei, Y.

    2005-01-01

    Introduction: Potassium (K) as a large ion lithophile element has dominantly been concentrated in the Earth s crust and the mantle through differentiation, and in the form of K-40 contributes to the planet s heat budget. However, whether or not K also enters core-forming phases, has been debated for over three decades. Arguments favoring entry of K in the core are based on: (1) K-sulfide (with Fe, Ni, Cu, Na, and Cl; djerfisherite) found in highly reduced enstatite chondrites (or aubrites, enstatite achondrites); (2) demonstration that K, owing to an s-d electronic switch at high-pressure, exhibits transition- element like character, (3) solubility of measurable K in Fe-Ni-S liquids at high pressure, temperature conditions, and (4) models of cooling of the core that seem to require, besides convection, some form of radioactivity, and thus lending support to the experimental work. In this contribution, we assess the effect of sequestering K in the core, as it is perhaps an element that is a key to reconciling geochemistry, paleomagnetism, accretion, and thermal evolution models for the planet.

  3. High-pressure polymorphism of Fe[subscript 2]P and its implications for meteorites and Earth's core

    Energy Technology Data Exchange (ETDEWEB)

    Dera, P.; Lavina, B.; Borkowski, L.A.; Prakapenka, V.B.; Sutton, S.R.; Rivers, M.L.; Downs, R.T.; Boctor, N.Z.; Prewitt, C.T. (UNLV); (UofC); (Univ of AZ); (CIW)

    2008-05-19

    Minerals with composition (Fe,Ni){sub 2}P, are rare, though important accessory phases in iron and chondritic meteorites. The occurrence of these minerals in meteorites is believed to originate either from the equilibrium condensation of protoplanetary materials in solar nebulae or from the later accretion and condensation processes in the cores of parent bodies. Fe-Ni phosphides are considered a possible candidate for a minor phase present in the Earth's core, and at least partially responsible for the observed density deficit with respect to pure iron. We report results of high-pressure high-temperature X-ray diffraction experiments with synthetic barringerite (Fe{sub 2}P) up to 40 GPa and 1400 K. A new phase transition to the Co{sub 2}Si-type structure has been found at 8.0 GPa, upon heating. The high-pressure phase can be metastably quenched to ambient conditions at room temperature, and then, if heated again, transforms back to barringerite, providing an important constraint on the thermodynamic history of meteorite.

  4. Fault-related-folding structure and reflection seismic sections. Construction of earth model using balanced cross section; Danso ga kaizaisuru shukyoku kozo no keitai to jishin tansa danmen. 1. Balanced cross section wo mochiita chika model no kochiku

    Energy Technology Data Exchange (ETDEWEB)

    Matsuoka, T.; Tamagawa, T. [Japan Petroleum Exploration Corp., Tokyo (Japan); Tsukui, R. [Japan National Oil Corp., Tokyo (Japan). Technology Research Center

    1997-05-27

    Pre-stacking depth migration treatment is studied for the estimation of the fold configuration from seismic survey cross sections. The estimation of a velocity structure is necessary for the execution of such treatment, and the utilization of structural-geological knowledge is required for its interpretation. The concept of balanced cross section in relation to the fault-bend fold constructs a stratum structure model under conditions that the deformation during fold and fault formation is a planar strain, that there is no change in volume due to deformation, and that a fold is a parallel fold. In addition to the above geometric and kinetic approach, there is another fold formation process simulation model using a Newtonian fluid for study from the viewpoint of dynamics. This simulation stands on the presumption that the boundary contains a ramp that had been in presence before fold formation and that an incompressible viscous matter is mounted on the top surface. The viscous matter flows and deforms for the formation of an anticline on the ramp. Such enables the reproduction of a fault-bend fold formation process, and helpful discussion may be furthered on the dynamic aspect of this simulation. 5 refs., 4 figs.

  5. The effect of temperature and pressure on optical absorption spectra of transition zone minerals - Implications for the radiative conductivity of the Earth's interior

    Science.gov (United States)

    Thomas, S.; Jacobsen, S. D.; Bina, C. R.; Goncharov, A. F.; Frost, D. J.; McCammon, C. A.

    2010-12-01

    and by two broad bands at ˜10000 cm-1 and ˜15000 cm-1, which are crystal field and intervalence charge transfer band, respectively. With increasing pressure the absorption spectra of both compositions change uniformly, crystal field and intervalence charge transfer bands continuously shift to higher frequencies. This has been observed for ringwoodite [2] but is contrary to earlier presumptions for wadsleyite [3]. Here, we present radiative conductivities calculated from high-pressure/high-temperature optical absorption spectra. Our results support earlier assumptions that transition zone minerals might contribute to radiative heat transfer in the Earth’s mantle. References: [1] Goncharov et al. (2008), McGraw Yearbook Sci. Tech., 242-245. [2] Keppler & Smyth (2005), Am. Mineral., 90 1209-1212. [3] Ross (1997), Phys. Chem. Earth, 22 113-118.

  6. Rare—Earth Element Geochemistry of Elogites from the Ultra—High Pressure Metamorphic Belt in Central China

    Institute of Scientific and Technical Information of China (English)

    黄智龙; 刘丛强; 等

    2000-01-01

    Based on their REE contents and REE patterns,eclogites from the ultra-high pressure metamorphic belt in central China may be roughly divided into xis types including LREE-rich.LREE-rich+positive Eu anomaly,LREE-rich+negative Eu anomaly,REE pattern-smooth,MREE-rich and HREE-rich.The LREE_rich,LREE-rich+positive Eu anomaly and LREE-rich+negative Eu anomaly types of eclogites are dominant .REE types of eclogites in different areas can be compared and the REE feactures of the same REE type of eclogites in different areas are similar.The results of reconstruction of the primary rocks show that the primary rocks of eclogites possibly are dominated by continental tholeiites which are the product of partial melting of relatively fertile mantle and the rocks of tholeiite crystallization-differentiation.There is perfect evolution relationship among the primary rocks of the LREE-rich, LREE-rich+positive Eu anomaly and LREE-rich+negative Eu anomaly types of eclogites and among those of the REE pattern smooth and MREE-rich types of eclogites,the former three types were deried from continental settings and the latter two from nearly oceanic settings.Meanwhile,it is concluded that the mantle sources of primary rocks of the eclogites are inhomogeneous and the primary rocks of eclogites in this area appear to have undergone varying degree of crustal contamination.

  7. The Earth's early evolution.

    Science.gov (United States)

    Bowring, S A; Housh, T

    1995-09-15

    The Archean crust contains direct geochemical information of the Earth's early planetary differentiation. A major outstanding question in the Earth sciences is whether the volume of continental crust today represents nearly all that formed over Earth's history or whether its rates of creation and destruction have been approximately balanced since the Archean. Analysis of neodymium isotopic data from the oldest remnants of Archean crust suggests that crustal recycling is important and that preserved continental crust comprises fragments of crust that escaped recycling. Furthermore, the data suggest that the isotopic evolution of Earth's mantle reflects progressive eradication of primordial heterogeneities related to early differentiation.

  8. `Galileo Galilei' (GG) small-satellite project: an alternative to the torsion balance for testing the equivalence principle on Earth and in space

    Science.gov (United States)

    Nobili, A. M.; Bramanti, D.; Polacco, E.; Roxburgh, I. W.; Comandi, G.; Catastini, G.

    2000-06-01

    `Galileo Galilei' (GG) is a proposal for a small, low-orbit satellite devoted to testing the equivalence principle (EP) of Galileo, Newton and Einstein. The GG report on the phase A study recently carried out with funding from ASI (Agenzia Spaziale Italiana) concluded that GG can test the equivalence principle to 1 part in 1017 at room temperature. The main novelty is to modulate the expected differential signal of an EP violation at the spin rate of the spacecraft (2 Hz). Compared with other experiments, the modulation frequency is increased by more than a factor of 104, thus reducing 1/f (low-frequency) electronic and mechanical noise. The challenge for an EP test in space is to improve over the sensitivity of ground-based experiments (about 1 part in 1012) by many orders of magnitude, so as to deeply probe a so far totally unexplored field; doing that with more than one pair of bodies is an unnecessary complication. For this reason GG is now proposed with a single pair of test masses. At present the best and most reliable laboratory-controlled tests of the equivalence principle have been achieved by the `Eöt-Wash' group with small test cylinders arranged on a torsion balance placed on a turntable which provides the modulation of the signal (a 1-2 h rotation period). The torsion balance is not a suitable instrument in space. We have designed and built the GGG (`GG on the Ground') prototype. It is made of coaxial test cylinders weakly coupled (via mechanical suspensions) and quickly rotating (6 Hz achieved so far); in addition, it is well suited to be flown in space - where the driving signal is about three orders of magnitude stronger and the absence of weight is very helpful - inside the coaxial, co-rotating GG cylindrical spacecraft. The GGG apparatus is now operational. Preliminary measurement data indicate that weakly coupled, fast-spinning macroscopic rotors can be a suitable instrument to detect small differential effects. Rotation (up to 6 Hz so far) is

  9. 土压平衡盾构伸缩螺旋机的设计%Design of earth pressure balance shield telescopic screw conveyor

    Institute of Scientific and Technical Information of China (English)

    洪秋华

    2011-01-01

    阐述了土压平衡盾构螺旋机的一种新型设计思路,提出了带导向柱油缸及双闸门系统的伸缩式螺旋机,提供了满足其推进要求所必须的参数,为盾构伸缩式螺旋机的实际应用提供了理论依据.

  10. A METHOD FOR CALCULATING UNLIMITED EARTH PRESSURE OF RETAINING WALL WITH TRANSLATION MODE%平移模式下挡墙非极限土压力计算方法

    Institute of Scientific and Technical Information of China (English)

    杨庆光; 刘杰; 何杰; 罗善煌

    2012-01-01

    在考虑挡墙平动位移效应和内摩擦角折减系数的基础上,利用薄层斜条分法,提出墙后填土为无黏性土时挡墙非极限主动和被动土压力计算公式.为验证该方法的可行性,对平移模式下挡墙进行主动和被动土压力模型试验,并利用该方法对2个模型试验进行计算分析.试验及计算结果均表明:不同s/sc比值情况下,主动土压力随深度增加表现出先增大后减小的趋势,且在0.6H(H为挡土墙高度)位置与库仑土压力曲线出现交点;被动土压力沿深度非线性增大,但其值均小于库仑被动土压力值;主动土压力合力作用点位置均高于库仑土压力合力作用点,而被动土压力合力作用点位置均低于库伦土压力合力作用点,并且随着s/sc比值的提高差距越大.%Considering the movement effect of translation mode, the friction angle reduction coefficient and the method of bevel-layer analysis, a method for calculating the unlimited active and passive earth pressures is deduced for cohesiveless soil retaining wall with translation mode. In order to validate the feasibility of the proposed approach, two model tests for active and passive earth pressures were conducted in laboratory, respectively; and the proposed method was used to analyze the two models. Experimental and theoretical results indicate that the curve of active earth pressure increases firstly and decreases then along the depth of retaining wall with different values of s/sc, and it has a point of intersection with the curve of Coulomb active earth pressure at the depth of 0.6H, where H is the wall height. The passive earth pressure keeps increasing along the depth of retaining wall and is always smaller than the Coulomb passive earth pressure. Further study indicates that the action point position of the active earth pressure is higher than that of the Coulomb passive earth pressure, and the action point position of the passive earth pressure is lower

  11. Microstructual investigation of mixed rar earth iron boron processed vis melt-spinning and high-pressure gas-atomization for isotrophic bonded permanent magnets

    Energy Technology Data Exchange (ETDEWEB)

    Buelow, Nicholas Lee [Iowa State Univ., Ames, IA (United States)

    2005-01-01

    A solid solution of three rare earths (RE) in the RE2Fe14B structure have been combined to create the novel mixed rare earth iron boron (MRE2Fe14B) alloy family. MRE2Fe14B exhibits reduced temperature dependent magnetic properties; remanence and coercivity. The desired form of MRE2Fe14B is a powder that can be blended with a polymer binder and compression or injection molded to form an isotropic polymer bonded permanent magnet (PBM). Commercially, Nd2Fe14B is the alloy of choice for PBMs. Powders of Nd2Fe14B are made via melt-spinning as can be MRE2Fe14B which allows for direct comparisons. MRE2Fe14B made using melt-spinning at high wheel speeds is overquenched and must be annealed to an optimal hard magnetic state. Due to the rare earth content in the MRE2Fe14B powders, they must be protected from the environment in which they operate. This protection is accomplished by using a modified fluidized bed process to grow a protective fluoride coating nominally 15nm thick, to reduce air oxidation. MRE2Fe14B has demonstrated reduced temperature dependent magnetic properties in ribbon and PBM form. The real challenge has been modifying alloy designs that were successfully melt-spun to be compatible with high-pressure gas-atomization (HPGA). The cooling rates in HPGA are lower than melt-spinning, as the powders are quenched via convective cooling, compared to melt-spinning, which quenches initially by conductive cooling. Early alloy designs, in gas atomized and melt-spun form, did not have similar phase compositions or microstructures. Alloy additions, such as the addition of zirconium as a nucleation catalyst, were successful in creating similar phases and microstructures in the HPGA powders and melt-spun ribbon of the same MRE2Fe14

  12. 平移变位模式下黏性土非极限主动土压力%Non-limit active earth pressure of cohesive backfill under translation mode

    Institute of Scientific and Technical Information of China (English)

    陈奕柏; 柯才桐; 曹雄; 高洪波

    2014-01-01

    针对经典朗肯与库仑土压力理论不能计算非极限土压力的事实。根据土体渐进破坏机理,结合已有文献对准主动状态下土体摩擦角、黏聚力发挥值与墙体位移关系的研究,采用水平层分析法,通过建立水平微元体基本受力平衡方程,推导出非极限状态下黏性土主动土压力分布的一阶微分方程式。在此基础上给出了土压力合力及其作用点位置计算式,相应简化条件下,所提公式能够简化为朗肯、库仑主动土压力公式。算例分析结果表明:理论计算值与实测值基本吻合,获得了平移变位模式下黏性土非极限土压力随位移变化的规律,对实际工程挡土墙的设计计算具有一定的参考价值。%The classic Rankine and Coulomb earth pressure theory can not be used to calculate the non-limit earth pressure.Based on the progressive rupture mechanism,and combined with the existing research on the relationships between the mobilized friction angle,cohesion force and the displacement of rigid retaining wall under inter-mediate active state,the horizontal slices analysis method is used to de-duce the first-order differential equations of the active earth pressure distribution of cohesive backfill un-der unlimited state by establishing the basic force equilibrium equations of horizontal element.Based on this,the formula of the earth pressure resultant force and its action point are given,which can be simpli-fied to Rankine’s and Coulomb’s earth pressure formula under corresponding simplified conditions.The result of example analysis show that the calculated and measured earth pressure match with each other, the change regulation of non-limit earth pressure of cohesive backfill under translation mode is obtained, and which can be used for the design of retaining wall in practical engineering.

  13. 考虑土拱效应的铁路刚性挡墙主动土压力计算方法%Calculation Method of Active Earth Pressure of Railway Rigid Retaining Wall Considering Soil Arch Effect

    Institute of Scientific and Technical Information of China (English)

    路维; 孙文君; 王学民; 杨鹏志; 崔立功

    2016-01-01

    对考虑土拱效应的水平微元滑裂体水平向及竖向静力平衡方程进行了分析,获得了平移模式下的刚性挡土墙侧向主动土压力、主动土压力合力及其作用点的计算公式,并与模型试验数据进行了比较.结果表明:本文得到的平移模式下刚性挡土墙墙后主动土压力分布与模型试验结果吻合较好,最大值比实测值略大;墙背主动土压力沿墙高呈非线性分布,墙背主动土压力合力作用点高度大于墙高的1/3.%This paper analyses the horizontal and vertical static equilibrium equations of horizontal differential sliding mass with soil arch. New formulas of rigid retaining wall lateral active earth pressure,active earth pressure resultant force and its action position were derived under translation mode. The Comparisons between the theoretical and measured values shown that the lateral active earth pressure distribution of rigid retaining wall under translation mode from the proposed formulas are agree well with results from the model test,and the maximum value from calculation is slightly larger than measured value. The distribution of the lateral active earth pressure is nonlinear along the wall height,and the action position of active earth pressure is larger than one third of the wall height.

  14. X-ray diffraction and Mössbauer spectroscopy study of fcc iron hydride FeH at high pressures and implications for the composition of the Earth's core

    Science.gov (United States)

    Narygina, Olga; Dubrovinsky, Leonid S.; McCammon, Catherine A.; Kurnosov, Alexander; Kantor, Innokenty Yu.; Prakapenka, Vitali B.; Dubrovinskaia, Natalia A.

    2011-07-01

    The phase fcc FeH x (x ~ 1) was synthesized at pressures over 30 GPa and temperatures over 1600(50) K. At room temperature this iron hydride is stable at pressures from 19(1) GPa up to at least 68(2) GPa (the highest pressure achieved in this study). A fit of the PV data collected for fcc FeH x at room temperature gives the following parameters for the equation of state: V 0 = 53.8(3) Å 3, K 0 = 99(5) GPa, K' = 11.7(5). Using this data the amount of H required to match the density of the Earth's core was estimated to be 0.5-1 wt.% hydrogen in the outer core and 0.08-0.16 wt.% hydrogen in the inner core. Our results also suggest that hydrogen and carbon do not occur together in the Earth's core.

  15. High-pressure synthesis and characterization of the rare-earth fluoride borate LaB{sub 2}O{sub 4}F

    Energy Technology Data Exchange (ETDEWEB)

    Hinteregger, Ernst; Kocsis, Krisztina; Hofer, Thomas S.; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Perfler, Lukas [Innsbruck Univ. (Austria). Inst. fuer Mineralogie und Petrographie

    2013-09-15

    The rare-earth fluoride borate LaB{sub 2}O{sub 4}F was synthesized under high-pressure/high-temperature conditions of 1.1 GPa and 1300 C in a Walker-type multianvil apparatus from lanthanum oxide, lanthanum fluoride, and boron oxide. The single-crystal structure determination revealed that LaB{sub 2}O{sub 4}F is isotypic to CeB{sub 2}O{sub 4}F. The compound crystallizes in the orthorhombic space group Pbca (no. 61) with eight formula units and the lattice parameters a = 8.2493(9), b = 12.6464(6), c = 7.3301(5) A, V = 764.7(2) A{sup 3}, R{sub 1} = 0.0354, and wR{sub 2} = 0.0474 (all data). The structure exhibits a 9+1 coordinated lanthanum cation, one threefold coordinated fluoride ion and a chain of corner-sharing [BO{sub 3}]{sup 3-} groups. In addition to the IR- and Raman-spectroscopic investigations, DFT calculations were performed to support the assignment of the vibrational bands. (orig.)

  16. 不同变位模式刚性挡土墙的动被动土压力%Dynamic passive earth pressure on retaining wall under various modes of movement

    Institute of Scientific and Technical Information of China (English)

    彭润民; 纪秋林

    2009-01-01

    Based on Mononobe-Okabe's postulation, the first-order differential equation for passive earth pressure on the retaining wall was set up for the translation(T)mode, movement modes of rotation around base(RB)and rotation around top (RT) by analyzing slice elements extracted from sliding soil wedge; and the formulas for calculating of the unit earth pressure, the resultant earth pressure and the action point of resultant pressure were given. The comparison between calculated results by the present formulas and Coulomb's theory shows that the unit earth pressure is nonlinearly distributed; and that the distance from the action point of resultant pressure to the base of wall increases with the order of (RB)mode, (T)mode, and (RT) mode.%基于Mononobe-Okabe假定,通过对滑动土体中水平薄层单元的分析,建立了墙体平动(T)模式、墙体绕基础转动(RB)模式和墙体绕墙顶转动(RT)模式下的被动土压力的一阶微分方程,给出了土压力强度、土压力合力、土压力作用点的理论计算公式,并将该理论计算公式与库仑理论结果进行了比较.结果表明:土压力强度分布呈曲线分布,合力作用点到墙底的距离依(RB)模式、(T)模式和(RT)模式次序增大.

  17. Temperature of Earth's core constrained from melting of Fe and Fe0.9Ni0.1 at high pressures

    Science.gov (United States)

    Zhang, Dongzhou; Jackson, Jennifer M.; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E. Ercan; Hu, Michael Y.; Toellner, Thomas S.; Murphy, Caitlin A.; Prakapenka, Vitali B.

    2016-08-01

    The melting points of fcc- and hcp-structured Fe0.9Ni0.1 and Fe are measured up to 125 GPa using laser heated diamond anvil cells, synchrotron Mössbauer spectroscopy, and a recently developed fast temperature readout spectrometer. The onset of melting is detected by a characteristic drop in the time-integrated synchrotron Mössbauer signal which is sensitive to atomic motion. The thermal pressure experienced by the samples is constrained by X-ray diffraction measurements under high pressures and temperatures. The obtained best-fit melting curves of fcc-structured Fe and Fe0.9Ni0.1 fall within the wide region bounded by previous studies. We are able to derive the γ-ɛ-l triple point of Fe and the quasi triple point of Fe0.9Ni0.1 to be 110 ± 5GPa, 3345 ± 120K and 116 ± 5GPa, 3260 ± 120K, respectively. The measured melting temperatures of Fe at similar pressure are slightly higher than those of Fe0.9Ni0.1 while their one sigma uncertainties overlap. Using previously measured phonon density of states of hcp-Fe, we calculate melting curves of hcp-structured Fe and Fe0.9Ni0.1 using our (quasi) triple points as anchors. The extrapolated Fe0.9Ni0.1 melting curve provides an estimate for the upper bound of Earth's inner core-outer core boundary temperature of 5500 ± 200K. The temperature within the liquid outer core is then approximated with an adiabatic model, which constrains the upper bound of the temperature at the core side of the core-mantle boundary to be 4000 ± 200K. We discuss a potential melting point depression caused by light elements and the implications of the presented core-mantle boundary temperature bounds on phase relations in the lowermost part of the mantle.

  18. 考虑挡墙位移效应的被动侧土压力计算方法%Computational method of earth pressure at passive side considering wall displacement effect

    Institute of Scientific and Technical Information of China (English)

    宋飞; 张建民

    2011-01-01

    挡土结构上土压力的计算是土力学和岩土工程领域的基本研究课题之一.实际工程中的土压力通常是介于主动土压力和被动土压力之间的某一值,墙后填土由于碾压具有较高的密实度.经典的朗肯和库仑土压力理论只能计算极限状态下的土压力,没有考虑挡墙的位移以及剪切过程中密砂的强度从峰值强度降低到残余强度这一强度变化特性对于土压力的影响.给出了考虑挡墙位移效应的被动侧土压力计算方法,该方法能够同时考虑剪切过程中密砂的强度从峰值强度降低为残余强度这一强度变化特性对被动土压力的影响.通过土压力模型试验结果对计算方法进行了初步验证,计算结果和试验结果吻合较好,表明了该方法的有效性.%Computation of earth pressure acting on retaining structures constitutes an important research subject in the field of geotechnical engineering.In many engineering practices, the retaining wall displacement causing the backfill yield sufficiently cannot take place so that the earth pressure may fall anywhere between active and passive earth pressures.Besides, due to compaction, the backfill is always dense and its shear resistance will decrease from peak resistance to residual state during shear.However, classic Rankine and Coulomb earth pressure theories can only evaluate the earth pressure at the active and passive state.And they cannot consider the effect of reduction of post-peak shear soil resistance on earth pressure.The development of earth pressure at the passive side with wall displacement is studied.On the basis a new methodology is developed to evaluate earth pressures at the passive side under any boundary strain constraint for a rigid retaining structure with translational movement.It can take into account the effect of wall displacement and the strength characteristic of dense sand on earth pressure.The agreement of calculated results with the

  19. 增高鞋垫对足底压力分布及后跟平衡的影响%The Effect of Heighten Insole on Pressure Distribution and Heel Balance

    Institute of Scientific and Technical Information of China (English)

    张先熠; 李悦; 李罗浩; 李波

    2013-01-01

    通过测量穿增高鞋垫前后足底压力参数,探究增高鞋垫对足底压力分布与后跟部位平衡的影响.用Footscan压力板与Novel鞋垫系统测量15名大学生穿板鞋及穿垫有增高鞋垫的板鞋行走时的压力参数,比较二者在足底7个分区的接触时间、峰值压强与冲量,以及后跟内外侧压力差值.结果显示:穿增高鞋垫后,足底各区域接触时间均延长,大部分区域峰值压强降低,部分冲量由前尖转移向后跟,后跟部位内外翻加剧,从而平衡稳定性能降低.%This study aimed to investigate the effect of heighten insole on plantar pressure distribution and heel balance by analyzing plantar pressure measurements with and without heighten insole. Footscan Force Plate and Novel Pedar - X system were used to measure plantar pressure for 15 undergraduates wearing board shoe with and without heighten insole. The measurements of two conditions were compared. Analysis parameters of seven regions included contact time, peak pressure, impulsing on and the force difference between medial heel and lateral heel. The results showed that when wearing heighten insole; the contact time was increased on all regions and peak pressure was decreased on most regions; some pressure was transferred from the toes to heel region; the balance and stability were decreased with heel supination increased.

  20. On the radial force balance in the quiet time magnetotail current sheet

    Science.gov (United States)

    Artemyev, A. V.; Angelopoulos, V.; Runov, A.

    2016-05-01

    Using Time History of Events and Macroscale Interactions spacecraft observations of the quite magnetotail current sheet within the r∈[9,35]RE region (r is the radial distance from Earth and RE is Earth's radius), we investigate the thermal plasma pressure distribution along the magnetotail. Taking advantage of flapping motions of an ensemble of current sheets at various distances, we estimate the current density magnitude jy (in GSM coordinates). Comparing the tension force jyBz (Bz is the magnetic field component) with the radial gradient of the plasma pressure demonstrates that this gradient is only a small fraction, ˜10-15%, of the Ampere force exerted on the cross-tail current, in the r > 15RE region. We also estimate the contribution of the electron temperature anisotropy to the pressure balance: in the r > 15RE region the corresponding force can balance only 10-15% of the observed tension force jyBz. Thus, we conclude that about 70% of the tension force is not balanced by the combination of isotropic radial pressure gradient or the electron anisotropy. We discuss mechanisms that could be responsible for balancing the magnetotail current sheet.

  1. Experimental analysis of passive earth pressure against rigid retaining wall under translation mode for finite soils%有限土体刚性挡墙平动模式被动土压力试验研究

    Institute of Scientific and Technical Information of China (English)

    应宏伟; 张金红; 王小刚; 李冰河; 朱伟

    2016-01-01

    It is inappropriate to calculate the earth pressure for finite soils using the classical Coulomb or Rankine earth pressure theory. A series of laboratory model tests with different widths of backfill are conducted for the passive case of a rigid retaining wall subjected to horizontal translation. The change in lateral earth pressure distribution from the at-rest condition to the passive condition is monitored by using a set of pressure cells. The particle image velocimetry technique is employed to observe the development of a failure zone in the soils. The experiment results show that there is a good agreement between the measured earth pressures and the Coulomb’s solution in the case of infinite soils. However, the passive earth pressures on the moving retaining wall for finite soils are much more than the Coulomb’s solution. With the decrease of the soil width, the limited displacement of the wall under passive state seems to increase, and the passive earth pressures also increase significantly when the heights of the application points of the resultant earth pressure move down gradually. Moreover, with the decrease of the soil width, the heave of the backfill surface increases gradually, the inclination angles of the slip surface increase slightly, and the lateral earth pressures on the fixed boundary also increase gradually.%经典的库仑或朗肯土压力理论无法适用有限土体情况下的土压力问题。利用研制的土压力试验模型装置,进行了一组不同填土宽度的刚性挡墙平动模式室内模型试验,采用微型土压力盒量测从静止状态到被动极限状态的水平土压力分布的变化,利用颗粒图像测速技术研究土体内滑裂面发展规律。试验结果表明:半无限土体情况下的被动土压力大小、分布和合力作用点与库仑被动土压力较为接近。而有限宽度情况下移动挡墙上各深度的被动土压力值均大于库仑被动土压力,且土体宽度

  2. Active Earth Pressure for Non﹣vertical Rigid Retaining Wall Considering Soil Arching Effect%考虑土拱效应的非垂直刚性挡墙主动土压力

    Institute of Scientific and Technical Information of China (English)

    孙文君; 宋杨; 王学民; 王蓉蓉; 杨鹏志

    2016-01-01

    为研究非垂直刚性挡墙的主动土压力计算方法,根据土拱效应原理、微分水平层法以及水平向静力平衡条件,得到了平移模式下非垂直刚性挡土墙墙后填土破裂角的计算式,并进一步根据力与力矩平衡条件获得了平移模式下非垂直刚性挡土墙墙后主动土压力、合力及其作用点等的计算式。通过计算对各种特殊情况下的破裂角和主动土压力进行分析,讨论了墙背倾角、墙土摩擦角等对破裂角、法向主动土压力系数、法向主动土压力和主动土压力合力作用点高度等的影响。该研究可为非垂直墙背的支挡结构设计中的主动土压力计算提供更为合理的理论支持。%Active earth pressure for non﹣vertical rigid retaining wall is studied. Considering soil arching effect,according to differential level layer method and horizontal static equilibrium,a new formula of the inclinations of sliding surface behind the inclined rigid retaining wall is obtained under translation mode. Then according to static and moment equilibrium,a new expression of the active earth pressure were derived,and those of the active earth force and the height of application of its is also putted for﹣ward. The special solutions of the failure angle and the active normal earth pressure are discussed under various boundary conditions. In addition,the effects of the inclination of wall﹣back surface,the internal friction angle of backfill and the wall﹣soil friction angle on the failure angle,the active normal earth pres﹣sure and its coefficient,and application height the active earth force is investigated. This study can provide a more reasonable theoretical support for the design calculation of the active earth pressure against the non﹣vertical rigid retaining structures.

  3. Balancing Work and Family: A Panel Analysis of the Impact of Part-Time Work on the Experience of Time Pressure

    Science.gov (United States)

    Laurijssen, Ilse; Glorieux, Ignace

    2013-01-01

    In this article we consider the consequences of work-family reconciliation, in terms of the extent to which the adjustment of the labour market career to family demands (by women) contributes to a better work-life balance. Using the Flemish SONAR-data, we analyse how changes in work and family conditions between the age of 26 and 29 are related to…

  4. Major element composition of an Early Enriched Reservoir: constraints from 142Nd/144Nd isotope systematics in the early Earth and high-pressure melting experiments of a primitive peridotite

    Science.gov (United States)

    Kondo, Nozomi; Yoshino, Takashi; Matsukage, Kyoko N.; Kogiso, Tetsu

    2016-12-01

    The Accessible Silicate Earth (ASE) has a higher 142Nd/144Nd ratio than most chondrites. Thus, if the Earth is assumed to have formed from these chondrites, a complement low-142Nd/144Nd reservoir is needed. Such a low-142Nd/144Nd reservoir is believed to have been derived from a melt in the early Earth and is called the Early Enriched Reservoir (EER). Although the major element composition of the EER is crucial for estimating its chemical and physical properties (e.g., density) and is also essential for understanding the origin and fate of the EER, which are both major factors that determine the present composition of the Earth, it has not yet been robustly established. In order to determine the major element composition of the EER, we estimated the age and pressure-temperature conditions to form the EER that would best explain its Nd isotopic characteristics, based on Sm-Nd partitioning and its dependence on pressure, temperature, and melting phase relations. Our estimate indicates that the EER formed within 33.5 Myr of Solar System formation and at near-solidus temperatures and shallow upper-mantle pressures. We then performed high-pressure melting experiments on primitive peridotite to determine the major element composition of the EER at estimated temperature at 7 GPa and calculated the density of the EER. The result of our experiments indicates that the near-solidus melt is iron-rich komatiite. The estimated density of the near-solidus melt is lower than that of the primitive peridotite, suggesting that the EER melt would have ascended in the mantle to form an early crust. Given that high mantle potential temperatures are assumed to have existed in the Hadean, it follows that the EER melt was generated at high pressure and, therefore, its composition would have been picritic to komatiitic. As the formation age of the EER estimated in our study precedes the last giant, lunar-forming impact, the picritic to komatiitic crust (EER) would most likely have been

  5. Balancing Audio

    DEFF Research Database (Denmark)

    Walther-Hansen, Mads

    2016-01-01

    This paper explores the concept of balance in music production and examines the role of conceptual metaphors in reasoning about audio editing. Balance may be the most central concept in record production, however, the way we cognitively understand and respond meaningfully to a mix requiring balance...... is not thoroughly understood. In this paper I treat balance as a metaphor that we use to reason about several different actions in music production, such as adjusting levels, editing the frequency spectrum or the spatiality of the recording. This study is based on an exploration of a linguistic corpus of sound...

  6. New analysis method of seismic active earth pressure and its distribution on a retaining wall%地震条件下挡土墙主动土压力及其分布的新分析法

    Institute of Scientific and Technical Information of China (English)

    张国祥

    2014-01-01

    The seismic active earth pressure calculations problem with pseudo-static method is translated into non-seismic active earth pressure calculations problem in this paper using the transform method with rotating calculation model of retaining wall. Depend on the non-seismic active earth pressure formulations with differential layer method, the analytical formulas of resultant force of seismic earth pressure, application position of resultant force and distribution of seismic earth pressure with differential layer method are obtained directly, and the analytical solution of critical rupture angle by graphic method. The influencing factors including horizontal and vertical seismic accelerations, batter angle of wall back,cohesion and external friction angle between filler and back of retaining wall, equispaced overloading can be considered. The formulas can be used for seismic active earth pressure calculations of cohesive soil or non-cohesive soil with common border condition. The rotating seismic angle method in this paper is that the seismic active earth pressure calculation model with pseudo-static method is firstly rotated into static active earth pressure calculation model, and the stress states of retaining wall and soil behind retaining wall are not changed, and then the seismic active earth pressures with pseudo-static method are solved by the calculation methods of static active earth pressures. The deducing process of seismic active earth pressure formulations with pseudo-static method is simplified and unified greatly by using the new method. The seismic active earth pressure theory with pseudo-static method is perfected much more.%采用旋转挡土墙计算模型的变换法,将在地震和拟静力法条件下主动土压力的求解问题转化为在静力条件下主动土压力的求解问题。根据在静力条件下水平层分析法的主动土压力推导结果,直接获得在地震条件下主动土压力强度分布、土压力合力及其

  7. High-pressure syntheses and characterization of the rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho)

    Energy Technology Data Exchange (ETDEWEB)

    Hinteregger, Ernst; Pitscheider, Almut; Wurst, Klaus; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie; Enders, Michael [Innsbruck Univ. (Austria). Inst. fuer Pharmazie

    2013-11-15

    The new rare-earth fluoride borates RE{sub 2}(BO{sub 3})F{sub 3} (RE = Tb, Dy, Ho) were synthesized under high-pressure/high-temperature conditions of 1.5 GPa/1200 C for Tb{sub 2}(BO{sub 3})F{sub 3} and 3.0 GPa/900 C for Dy{sub 2}(BO{sub 3})F{sub 3} and Ho{sub 2}(BO{sub 3})F{sub 3} in a Walker-type multianvil apparatus from the corresponding rare-earth sesquioxides, rare-earth fluorides, and boron oxide. The single-crystal structure determinations revealed that the new compounds are isotypic to the known rare-earth fluoride borate Gd{sub 2}(BO{sub 3})F{sub 3}. The new rare-earth fluoride borates crystallize in the monoclinic space group P2{sub 1}/c (Z = 8) with the lattice parameters a = 16.296(3), b = 6.197(2), c = 8.338(2) A, {beta} = 93.58(3) for Tb{sub 2}(BO{sub 3})F{sub 3}, a = 16.225(3), b = 6.160(2), c = 8.307(2) A, {beta} = 93.64(3) for Dy{sub 2}(BO{sub 3})F{sub 3}, and a = 16.189(3), b = 6.124(2), c = 8.282(2) A, {beta} = 93.69(3) for Ho{sub 2}(BO{sub 3})F{sub 3}. The four crystallographically different rare-earth cations (CN = 9) are surrounded by oxygen and fluoride anions. All boron atoms form isolated trigonal-planar [BO{sub 3}]{sup 3-} groups. The six crystallographically different fluoride anions are in a nearly planar coordination by three rare-earth cations. (orig.)

  8. Balanced sampling

    NARCIS (Netherlands)

    Brus, D.J.

    2015-01-01

    In balanced sampling a linear relation between the soil property of interest and one or more covariates with known means is exploited in selecting the sampling locations. Recent developments make this sampling design attractive for statistical soil surveys. This paper introduces balanced sampling

  9. Dynamic Active Earth Pressure on Retaining Wall under Various Modes of Movement%不同变位模式下刚性挡土墙的动主动土压力

    Institute of Scientific and Technical Information of China (English)

    李刚; 张凤涛

    2011-01-01

    On the basis of the Assumption of Mononobe-Okabe theory,the first-order differential equation for active earth pressure on the retaining wall was set up for the translation (T) mode, movement modes of rotation around base (RB) and rotation around top (RT) by analyzing slice elements extracted from the sliding soil wedge. And the formulas for calculating the unit earth pressure, the resultant earth pressure and the action point of the result pressure were given. The comparison between calculated results with the present formulas and Mononobe-Okabe theory has shown that the unit earth pressure is nonlinear-ly distributed;and that the distance from the action point of resultant pressure to the base of wall increases with the order of(RB)mode,(T) mode,and (RT) mode. It has also indicated that the calculated results of the resultant pressure under various modes of movement are in accordance with those of Mononobe-Okabe theory for q0 = 0 .%基于Mononobe-Okabe理论的基本假设,通过对滑动土体中水平薄层单元的分析,建立了墙体平动(T)模式、墙体绕基础转动(RB)模式和墙体绕墙顶转动(RT)模式下的主动土压力的一阶微分方程式,给出了土压力强度、土压力合力、土压力作用点的理论计算公式,并将该理论计算公式与Mononobe-Okabe理论结果进行了比较.结果表明:土压力强度分布呈非线性分布,合力作用点到墙底的距离依(RB)模式、(T)模式和(RT)模式次序增大.当地面荷载q0=0时,各种墙体变位模式下的动土压力合力与Mononobe-Okabe理论相同.

  10. 考虑土拱效应的刚性挡墙主动土压力分析%Analysis of active earth pressure on rigid retaining walls considering soil arching

    Institute of Scientific and Technical Information of China (English)

    王杰; 夏唐代; 贺鹏飞; 黄博

    2014-01-01

    以墙后填土为无黏性土的刚性挡土墙为研究对象,考虑墙后土体的土拱效应,修改了 Shubhra Geol 抛物线形土拱表达式,推导了对应不同内摩擦角和墙-土摩擦角的挡土墙平动模式下的主动土压力系数。基于水平微分单元法,得到考虑土拱效应的主动土压力分布、合力大小和合力作用点高度的理论表达式,并与现有经典理论解及前人理论研究成果和模型试验数据进行对比分析,结果表明,主动土压力与墙-土接触面摩擦角、土体内摩擦角、土体重度和挡墙高度相关,土压力分布为非线性,与其他结果比较吻合,从而验证了该研究成果的正确性。%Taking a rigid retaining wall with cohesionless backfill for example, considering the soil arching, the active earth pressure factor is derived for retaining wall under translation mode with different internal friction angles and wall-soil friction angles. The Shubhra Geol parabolic soil arching expression is modified. Based on horizontal differential element method, new formulations are proposed for calculating the active earth pressure, the resultant earth pressure and its action point. In order to check the accuracy of the proposed formulation, the predictions from the equation are compared with the results of full-scale test and existing classical theory. The results show that the active earth pressure is related to wall-soil friction angle, the internal friction angle, the unit weight of backfill and the height of retaining wall. It is shown that the earth pressure is nonlinear and the previous research results show great agreement with each other;and the correctness of the results is verified.

  11. Theory of earth pressure against rigid retaining wall based on disturbed state concept model%基于扰动状态概念模型的刚性挡土墙土压力理论

    Institute of Scientific and Technical Information of China (English)

    朱剑锋; 徐日庆; 王兴陈

    2011-01-01

    基于扰动状态概念(DSC),结合库伦土压力理论研究平动位移模式下刚性挡土墙的土压力计算方法.以挡墙平动位移量为扰动参量,建立扰动度函数表达式.提出扰动摩擦角概念,建立扰动摩擦角与扰动度之间的关系公式.参照库仑土压力理论,分析任意扰动状态下土楔的最不利受力情况,得到平动位移模式下基于DSC理论刚性挡土墙土压力计算公式.算例分析表明:在任意扰动状态下,基于DSC理论的刚性挡墙土压力计算公式所预测的土压力大小、分布以及土压力系数均与模型试验结果比较吻合.%Through combining with the Coulomb's earth pressure theory, the method of calculating earth pressure against rigid retaining wall under translation mode was studied based on the disturbed state concept (DSC). The disturbance function was established by taking the movement of rigid retaining wall as the disturbed parameter. The disturbed frictional angle concept was proposed and the relationship between the disturbed frictional angle and the disturbed degree was obtained. By analyzing the forces on the most unfavorable soil wedge at arbitrary disturbed state, the general formulas for calculating the earth pressure against rigid retaining wall under translation mode were established based on DSC theory. Calculation results shows that the predicted magnitude and distribution of earth pressure and the coefficients of earth pressure agree well with those of the model test at random disturbed state.

  12. Analysis of Facing Earth Pressure of Soil-nailing Wall on Double-parameter Foundation%双参数地基上土钉墙面层土压力计算

    Institute of Scientific and Technical Information of China (English)

    王立峰; 祝江鸿

    2012-01-01

    土钉墙面层承受部分土(水)压力,文中把土钉墙面层看作是弹性地基上的有限长梁,在试验的基础上,推导了基于双参数地基的成层土层分布的土钉墙面层在土钉拉力作用下的挠曲线、转角、弯矩和剪力方程,并与实测数据进行了比较分析,验证了模型的合理性,得到的解析解基本上可以反映土钉墙面层土压力的分布.在此基础上,探讨了不同土性土层中土钉墙面层土压力的分布.面层土压力在土层的分界面上位移连续土压力突变;作用在软弱土层的面层土压力比硬土层上的面层土压力大;上软下硬型较上硬下软的土层分布更能使面层土压力得到充分发挥;同时文中计算了面层土压力换算成荷载与土钉拉力的比值,面层对于土压力的作用随着深度的增加表现得愈加明显,提出针对不同地区不同深度和不同土性条件下应给出比值的建议值,以使土钉墙的设计更符合其真实的作用机理.文中得到的结论和计算方法对于进一步研究土钉墙的作用机理及设计中如何充分发挥面层的作用等具有重要的理论意义和实际应用价值.%Present designers of soil-nailing walls consider the facing as accessory structure rather than the main one. However It is absolutely sure that the facing bear against water and earth pressure. Facing isolated and considered as finite beam on elastic foundation simply .solutions of displacement ^angles of rotation,bending moment and shear force of soil-nailing walls are gained on basis of field tests in layered soil. Rationality of the model is tested and verified. The results that can disclose laws of distribution of facing earth pressure are in agreement with the actual measurement datum. Earth pressure in bounding surface shows abrupt changes while displacement of facing exhibits continuous characteristics. Earth pressure of facing applied by soft soil presents bigger values than that of

  13. Effects of local fatigue on myoelectrical activity of erector spine muscles and the center for pressure displacement of the feet during balance recovery following postural perturbation in kyphotic subjects

    Directory of Open Access Journals (Sweden)

    Rooholah Rezaee

    2014-07-01

    Full Text Available Background: kyphosis deformity affects postural control. Muscular fatigue is one of the factors that can impair the mechanism of body balance. The aim of this study was to determine the effects of local fatigue on the myoelectrical activity of erector spine muscles and the center for pressure displacement of the feet during balance recovery following postural perturbation in kyphotic subjects. Methods: In this quasi-experimental study, 12 male students with>40 degrees thoracic kyphosis and 12 controls were selected to participate in the study. A flexible ruler was used to measure thoracic kyphosis. For postural control assessment, each subject underwent unexpected, forward-backward perturbations while standing on a foot scan mounted on a movable plate triggered by a weight equivalent to 10% of the subjects’ body weight. Experimental procedure was measured before (3 trails and after (3 trials the fatigue protocol. The myoelectric activity of the erector spine and multi fidus was compared in the groups using repeated measures of ANOVA and independent t-test (P<0.05. Results: There was no significant difference in the foot center of pressure displacement in both groups after muscular fatigue. After fatigue, there was an increase in the activity of longissimus thoracis (P=0.001 and iliocostalis thoracis (P= 0.001 in control group, while no significant difference was reported for the muscular activity of multifidus (p=0.084. The activity of langisimus thoracis was significantly increased (P=0.028 in kyphtic group after fatigue. Conclusion: erector spine muscles fatigue could not significantly affect the postural control in both groups, but the electrical activity of erector spine muscles during balance recovery following postural perturbation in kyphotic subjects was different than the controls.

  14. Balancing Acts

    Science.gov (United States)

    ... new type of balance therapy using computerized, virtual reality. UPMC associate professor Susan Whitney, Ph.D., developed ... virtual grocery store in the university's Medical Virtual Reality Center. Patients walk on a treadmill and safely ...

  15. Balance Problems

    Science.gov (United States)

    ... fall may affect an older adult's life. BPPV (Benign Paroxysmal Positional Vertigo) There are many types of balance disorders. One of the most common is benign paroxysmal positional vertigo, or BPPV. In BPPV, you experience a brief, ...

  16. 姿势控制训练对偏瘫患者足底压力及平衡功能的影响%Influence of postural control training on plantar pressure and balance function of hemiparalysis patient

    Institute of Scientific and Technical Information of China (English)

    刘蓓蓓; 丁勤能; 王岩

    2014-01-01

    Objective To explore the influence of postural control training on plantar pressure and balance function of hemip -aralysis patient .Methods Twenty-four cases of hemiparalysis patients were selected and divided into two groups of traditional group ( TG) and balance group ( BG) and had been taken postural control trainings .Novel Zebris pressure test platform was used to examine the pressure peak value (PPV),average pressure (AP),ellipse track length (ETL) of pressure center deviation including ellipse area ( EA) after postural control trainings .Results After two different training methods:①Compared with TG ,PPVs of front half foot and back half foot of unaffected side were both decreased significantly (P0.05).②Compared with TG,AP of front half foot in unaffected side decreased significantly and that in back half foot in-creased significantly (P0.05).③Compared BG with TG,EA,ETL and ratio between ETL and EA decreased significantly (P<0.05).Conclusion ①After two pos-tural control trainings ,there is no significant alteration on contact mode between feet and ground ,and feet pressure distribution condi-tion.Body’s methods to maintain balance have not been changed .②Both feet pressure balance abilities of hemiparalysis patients have been improved after two postural control trainings that indicate they are effective to increase hemiparalysis patients ’ balance function .③Steady trainings in BG promote the improvement of balance function and coordination ability .④BG had obvious advantages than TG in regaining balance adjustment function .%目的:探讨偏瘫患者在进行姿势控制训练后足底压力的变化及对平衡功能的影响。方法将24例偏瘫患者随机分为传统组和平衡组并进行姿势控制训练。使用Novel Zebris平板式足底压力系统测试患者训练后足底的压力峰值、平均压力、压力中心偏移的椭圆轨迹长度,以及椭圆轨迹包络面积。结果经过姿势训练后,①平衡组

  17. Chaotic behavior in a system simulating the pressure balanced injection system. Analysis of passive safety reactor behavior. JAERI's nuclear research promotion program, H12-012 (Contract research)

    Energy Technology Data Exchange (ETDEWEB)

    Madarame, Haruki; Okamoto, Koji; Tanaka, Gentaro; Morimoto, Yuichiro [Tokyo Univ., School of Engineering, Tokyo (Japan); Sato, Akira [Yamagata Univ., Faculty of Engineering, Yonezawa, Yamagata (Japan); Kondou, Masaya [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    2003-03-01

    The pressure Balanced Injection System (PBIS) was proposed in a passive safety reactor. Pressurizing Line (PL) connects the Reactor Vessel (RV) and the gas area in the Contain Vessel (CV), and Injected Line (IL) connects two vessels at relatively lower position. In an accident, the two lines are passively opened. The vapor generated by the residual heat pressed downward the water level in the RV. When the level is lower than the inlet of the PL, vapor is ejected into the CV through the PL attaining the pressure balance between the vessels. Then boron water in the CV is injected into the RV through the IL by the static head. This process is repeated by the succeeding vapor generation. In an experiment, the oscillating system was replaced by water column in a U-shaped duct. The vapor generation was simulated by cover gas supply to one end of the duct, while the other end was open to the atmosphere. When the water level reached a certain level, electromagnetic valves opened and the cover gas was ejected. The gas pressure decreased rapidly, resulting in a surface rise. When the water level reached another level, the valves closed. The cover gas pressure increased again, thus, gas ejection occurred intermittently. The interval of the gas ejection was not constant but fluctuated widely. Mere stochastic noise could hardly explain the large amplitude. Then was expressed the system using a set of linear equations. Various types of piecewise linear model were developed to examine the cause of the fluctuation. There appeared tangential bifurcation, period-doubling bifurcation, period-adding bifurcation and so on. The calculated interval exhibited chaotic features. Thus the cause of the fluctuation can be attributed to chaotic features of the system having switching. Since the piecewise linear model was highly simplified the behavior, a quantitative comparison between the calculation and the experiment was difficult. Therefore, numerical simulation code considering nonlinear

  18. MASS BALANCE GEOCHEMISTRY OF THE RED EARTH IN SOUTHERN CHINA AND ITS ENVIRONMENTAL IMPLICATIONS%南方红土元素迁移特征及其古环境意义

    Institute of Scientific and Technical Information of China (English)

    熊尚发; 丁仲礼; 刘东生

    2001-01-01

    The soil responses to climatic changes are a key problem in the studies of global change. Soils in the past provide a valuable record for the understanding of the relationship between the soil and the climatic changes. Here we report a case study to the red earth section at Jiujiang City in southern China. This section is about 15m in thickness, and consists of two pedogenic units. The upper part is a layer of yellowish silty clay, while the lower part a layer of red clay with yellow and white worm-shaped veins. Mass-balance equations applied to geochemical analyses reveal that the degree of weathering increased down-section and the concentration of resistate constituents decreased upward. A pronounced depletion of bases(Na, K) has been shown in the lower part of the section. This weathering trend is not observed in the loess sections in northern China, and is probably the results of Quaternary climatic changes in southern China and of the variations in dust input resulting from the deterioration over central Asia.%气候变化下土壤物质过程的响应特征是全球变化研究的重要主题。本文选取江西九江剖面,通过协变分析,对其元素迁移特征进行了研究。结果显示,剖面上部(褐黄色土层)和剖面下部(网纹红土层)的协变状态和元素迁移强度有明显的差别,从盐基赋存状态看,剖面下部元素迁移强度大大高于剖面上部,同时,不同元素的迁移模式的表现明显不同。研究表明,剖面元素组成主要受古气候变化引起的风化强度差异的控制,但也在一定程度上受母质物源变化的影响。

  19. 基于PSO搜索潜在滑裂面非极限状态土压力计算%Computation of Earth Pressure under Non-limit State Based on PSO Search of Potential Slip Surface

    Institute of Scientific and Technical Information of China (English)

    陈昌富; 肖重阳; 唐仁华

    2013-01-01

    The computation of earth pressure against rigid retaining wall usually adopts classical Ran-kine or Coulomb's theory, which can only get limit state of earth pressure, but in many practical cases, the earth pressure against retaining wall is in the non-limit state. So, this paper presented an analysis of the backfill under the mode of translation based on the improved thin-layer element method and the relationship between friction angle and displacement variation. The distribution of earth pressure, resultant force and its action point of a retaining wall under non- limit state were obtained. The optimal solution of earth pressure was obtained by using PSO (particle swarm optimization) to search the potential slip surface, on which the inclination angle of the segment for the thin layer element was extracted as a valuable. Then, the effects of the internal frictional angle, wall displacement on the distribution of earth pressure, resultant force, action point and potential slip surface were discussed. Finally, the results of the proposed method were compared with laboratory test data, which shows that the calculated results have a good agreement with the experimental observations.%作用于刚性挡土墙侧土压力的计算一直沿用经典的朗肯或库仑土压力理论,这两种理论只能求得极限状态的土压力,而在许多实际情况下,挡土墙的土压力处于非极限状态,本文将潜在滑裂面视为一任意曲线,改进水平层分析法,同时基于摩擦角随位移的变化关系,对平动模式下墙后填土进行分析,推导出非极限状态下主动方向土压力分布、合力大小及作用点的理论公式.以各薄层微元的滑裂面倾角为变量,利用PSO(粒子群算法)对潜在滑裂面进行搜索从而获得土压力最优解.分析了内摩擦角、刚性挡土墙位移量对非极限状态主动方向土压力分布、土压力合力大小、土压力合力作用点高度以及潜在滑裂面的影响.本文

  20. 考虑土拱效应的非垂直挡墙地震主动土压力%SEISMIC ACTIVE EARTH PRESSURE FOR NON-VERTICAL RIGID RETAINING WALL CONSIDERING SOIL ARCHING EFFECT

    Institute of Scientific and Technical Information of China (English)

    周亦涛; 陈福全

    2015-01-01

    The stresses on the wall and sliding plane of the sliding backfill mass at arbitrary depths were obtained according to the soil arching effect. A formula of the seismic active failure angle behind the non-vertical rigid retaining wall under translation mode was obtained on the basis of the pseudo-static method and the equilibrium total forces. A formula of the seismic active earth pressure against the non-vertical rigid retaining wall under translation mode was derived according to the method of differential level layer. The seismic active earth force and the action point were obtained. The distribution of seismic active earth pressure from the proposed formula was non-linear along the height of wall. In addition,the influences of the wall-back inclination,internal friction angle of backfill,wall-soil friction angle,seismic coefficient and load against the backfill surface on the seismic failure angle,seismic active earth pressure and its coefficient,seismic active earth force and height of its application were investigated.%由土拱效应原理得到滑裂土体的墙面和滑裂面上的应力,然后根据拟静力法和滑裂土体的整体受力平衡,得到平移模式下非垂直刚性挡土墙的地震主动破裂角计算式.进一步根据水平层分法获得墙背地震主动土压力及其系数、地震主动土压力合力及其作用点高度等的计算式.此外,分别讨论墙背倾角、填土内摩擦角、墙土摩擦角、地震系数和填土表面荷载等对地震主动破裂角、法向地震主动土压力分析、地震主动土压力合力系数、地震主动土压力合力及其作用点相对高度等的影响.

  1. 非饱和土强度非线性及对被动土压力的影响%Nonlinearity of unsaturated soils strength and its influence on passive earth pressure

    Institute of Scientific and Technical Information of China (English)

    张常光; 赵均海; 张冬芳

    2012-01-01

    In order to investigate the nonlinearity of unsaturated soil strength and its influence on passive earth pressure, the advances in the study of nonlinearity of unsaturated soil shear strength are reviewed, and based on the piecewise shear strength formula for unsaturated soil, a shear strength parameter under high matric suction is derived. Then, the parameter is applied to the calculation of passive earth pressure of unsaturated soil. The results show that high matric suction has a dual effect which can be divided into three situations according to the relationship between reducing and strengthening. As matric suction increases, the corresponding passive earth pressure decreases gradually and stabilizes, or increases slightly, or increases significantly, which actually reflects the nonlinearity of unsaturated soils strength under high matric suction.%为研究非饱和土强度的非线性及其对被动土压力的影响,文中在介绍非饱和土强度非线性研究进展的基础上,结合分段抗剪强度公式拟合了一个高吸力抗剪强度参数,并将这一参数应用于非饱和土被动土压力的计算.研究结果表明:高基质吸力具有双重影响,按减小影响和增大效应间的相对关系可分为3种情况,所对应的被动土压力随着基质吸力的增大,或逐渐减小并最终趋于稳定,或略有增加,或大幅度增加,这实际反映的是高基质吸力下非饱和土强度的非线性规律.

  2. Expanding earth

    Energy Technology Data Exchange (ETDEWEB)

    Carey, S.W.

    1976-01-01

    Arguments in favor of an expanding earth are presented. The author believes that the theory of plate tectonics is a classic error in the history of geology. The case for the expanding earth is organized in the following way: introductory review - face of the earth, development of expanding earth concept, necessity for expansion, the subduction myth, and definitions; some principles - scale of tectonic phenomena, non-uniformitarianism, tectonic profile, paleomagnetism, asymmetry of the earth, rotation of the earth, and modes of crustal extension; regional studies - western North America, Central America, South-East Asia, and the rift oceans; tests and cause of expansion. 824 references, 197 figures, 11 tables. (RWR)

  3. Passive earth pressure on retaining walls calculated by principle of soil arching effect%基于土拱效应原理求解挡土墙被动土压力

    Institute of Scientific and Technical Information of China (English)

    侯键; 夏唐代; 孔祥冰; 孙苗苗

    2012-01-01

    In the translational displacement mode, a stress of wedge soil between rigid retaining wall and sliding surface, which is in the passive state of limit equilibrium, is analyzed. Considering the horizontal equilibrium of the soil between the wall and the slip surface, the formula of passive earth pressure coefficient and the angle of failure line to horizontal are obtained by using the principle of soil arching effect. According to the equilibrium equation considering the static equilibrium conditions of horizontal unit of soil, the formula of the passive earth pressure distribution, the resultant earth pressure and the application point of resultant earth pressure on retaining wall are respectively set up. After comparing the computed result using the method mentioned above with the experiment results and the results obtained on the basis of Coulomb and Rankine theories, it is demonstrated that the calculating results agree well with the experimental results; and thus the calculating method obtained is verified rational.%对平移模式下的刚性挡土墙和滑裂面间的楔形土体处于被动极限平衡状态的应力进行分析,考虑墙面和滑裂面之间土体水平力平衡,运用土拱效应原理推导出被动土压力系数和滑裂面水平倾角.并根据水平单元土体的静力平衡条件建立平衡方程,提出被动土压力分布、土压力合力及其作用位置的公式.将公式计算结果与试验结果以及库仑、朗肯理论所得结果进行比较,结果表明,与试验结果接近,验证了所得计算方法的合理性.

  4. Chronic blood pressure control.

    Science.gov (United States)

    Brands, Michael W

    2012-10-01

    Chronic blood pressure is maintained within very narrow limits around an average value. However, the multitude of physiologic processes that participate in blood pressure control present a bewildering array of possibilities to explain how such tight control of arterial pressure is achieved. Guyton and Coleman and colleagues addressed this challenge by creating a mathematical model that integrated the short- and long-term control systems for overall regulation of the circulation. The hub is the renal-body fluid feedback control system, which links cardiac function and vascular resistance and capacitance with fluid volume homeostasis as the foundation for chronic blood pressure control. The cornerstone of that system is renal sodium excretory capability, which is defined by the direct effect of blood pressure on urinary sodium excretion, that is, "pressure natriuresis." Steady-state blood pressure is the pressure at which pressure natriuresis balances sodium intake over time; therefore, renal sodium excretory capability is the set point for chronic blood pressure. However, this often is misinterpreted as dismissing, or minimizing, the importance of nonrenal mechanisms in chronic blood pressure control. This article explains the renal basis for the blood pressure set point by focusing on the absolute dependence of our survival on the maintenance of sodium balance. Two principal threats to sodium balance are discussed: (1) a change in sodium intake or renal excretory capability and (2) a change in blood pressure. In both instances, circulatory homeostasis is maintained because the sodium balance blood pressure set point is reached.

  5. On mining technology of engineering pressure-type rare earth resources%工程压覆型稀土资源的开采技术探究

    Institute of Scientific and Technical Information of China (English)

    张新光

    2016-01-01

    结合广西贺州境内被2条高速线路(永贺高速公路和贵广高速铁路)压覆的稀土资源的抢救性回收工程实例,探讨了原地浸矿技术对压覆型离子稀土资源开采的实用性和有效性,分析了影响“原地浸矿”和“堆浸”2种稀土资源开采工艺回收率的主要因素,并对其回收工艺进行了优化,探索出了一种绿色的、高效的压覆型稀土资源的开采工艺。%This paper,combining with rare earth resources overlaid by salvaging recycling projects in two highways of Hezhou Guangxi,that is the Yongzhou-Hezhou Highway and the Guiyang-Guangzhou Highway, discusses the practicability and effectiveness of in-situ leaching technology for exploiting ion-type rare earth resources overlaid by projects.In addition,it also analyzes main factors of impacting mining teaching recovery of two rare earth resources,including “in-situ leaching”and “heap leaching”,optimizes its recovery process, and explores a green and efficient mining technology of rare earth resources overlaid by projects.

  6. Experimental study on thermal balance performance of naturally aspirated diesel engine at high altitude (low air pressure)%自然吸气柴油机高海拔(低气压)热平衡试验研究

    Institute of Scientific and Technical Information of China (English)

    董素荣; 许翔; 任晓江; 关立哲; 郑智; 刘瑞林

    2011-01-01

    基于内燃机高海拔(低气压)热平衡模拟试验台,对某型内燃叉车自然吸气柴油机进行了热平衡高原模拟试验,研究了柴油机燃烧放热量分配、冷却液温度以及排气温度等随海拔高度(大气压力)的变化规律.结果表明:随着海拔的升高,转化为有效功的热量、冷却水散热量以及排气带走的热量均不断下降,柴油机不完全燃烧造成的热损失、机体散失的热量以及其他热损失所占比重不断增加;与平原相比,海拔5 000 m时,转化为有效功的热量平均下降了13.79%,冷却水散热量平均下降了2.27%,排气带走的热量平均下降了14.4%,发动机的热平衡性能与平原相比发生了较大的变化.%The thermal balance performance of naturally aspirated forklift diesel engine at different altitudes was studied on the engine thermal balance test bed for simulating with high altitude (low air pressure). Influence of atmospheric pressure on the heat distribution, coolant temperature and exhaust gas temperature were analyzed. Results show that thermal changed into usable power, thermal carried by cooling water and exhaust gas decreased with the increase of altitude. On the contrary, the heat loss due to incomplete combustion increased with the increase of altitude. Compared with that at 5 000 m altitude, thermal changed into usable power decreased by 13. 79%; thermal carried by cooling water decreased by 2. 27%; thermal carried by exhaust air decreased by 14.4%. The thermal balance performance at high altitude is different from the performance at sea level.

  7. Balance (or Vestibular) Rehabilitation

    Science.gov (United States)

    ... the Public / Hearing and Balance Balance (or Vestibular) Rehabilitation Audiologic (hearing), balance, and medical diagnostic tests help ... whether you are a candidate for vestibular (balance) rehabilitation. Vestibular rehabilitation is an individualized balance retraining exercise ...

  8. 考虑土拱效应平移挡土墙地震主动土压力分布%Distribution of Seismic Active Earth Pressure of Retaining Wallin Translation Mode Considering Soil Arching

    Institute of Scientific and Technical Information of China (English)

    张琪昌; 鹿兴; 李栋

    2015-01-01

    基于Mononobe-Okabe理论,考虑土拱效应并假设土拱形状为圆弧形,通过对墙后土体的应力分析推导出在地震作用下土拱形状的曲线方程、侧土压力系数以及水平微分土层间平均剪应力与平均竖向应力二者关系的理论公式。采用水平层分析法推导出平移模式下挡土墙地震主动土压力分布、土压力合力以及合力作用点高度的理论公式,并与 Mononobe-Okabe 理论、前人方法以及试验数据进行对比分析。结果表明:随着地震系数的增大,土拱形状由下凹圆弧变为下凸圆弧,侧土压力系数也呈现增大趋势;计算出的地震土压力合力与 Mononobe-Okabe 理论计算值相等,但其分布为非线性分布;与现有理论相比,合力作用点高度与试验结果比较吻合。%Based on Mononobe-Okabe theory,considering arch effect and assuming that soil arching was in the form of circle,after analyzing the stress of the filling behind retaining wall,the equation of soil arching was obtained,as well as the lateral earth pressure coefficient and a theory formula which is to calculate the relationship between the average shear stress and the average vertical stress on the horizontal differential elements.By using the method of horizontal differential element,an improved formula of the distribution of seismic active earth pressure resultant force and its points of application were obtained.The proposed method was compared with the existing methods and experimental data.It shows that the resultant seismic earth pressure is the same as that given by Mononobe-Okabe theory.The distribution of seismic earth pressure is non-linear.With the increase of seismic coefficient,soil arch shape changes,the coefficients of lateral earth pressure also increases.Compared with the existing theory,the heig-hts of points of application of the resultant force of proposed method are in consistence with the results of model test.

  9. Limit analysis of seismic active earth pressure of multistage retaining structures%多级支挡结构地震主动土压力的极限分析

    Institute of Scientific and Technical Information of China (English)

    文畅平

    2013-01-01

    多级组合支挡结构形式在高边坡防护工程中得到了广泛采用,但现有研究却较少涉及这种支挡结构形式的地震土压力计算问题。应用拟静力法和塑性极限分析上限定理,并且基于强度折减技术,推导了重力式挡墙与两级锚杆挡墙组合支挡结构形式的地震主动土压力及其系数的上限解。该上限解考虑了水平和竖向地震系数、墙背倾角、坡面形式及多级支护方式、土体黏聚力、土体与墙背的黏附力等诸多因素。二级锚杆挡墙实例分析表明:静力条件下主动土压力计算值与现有相关方法的计算结果一致,土的抗剪强度折减系数、上挡墙锚杆轴力等参数,对下挡墙地震主动土压力影响显著。二级组合支挡结构地震主动土压力影响参数敏感性分析表明:水平地震系数以及重力式挡墙墙高和倾角的敏感性较大,上挡墙锚杆的轴力和倾角等参数的敏感性相对较小。%Multistage and combination retaining structures are employed widely in high slopes; but the seismic earth pressure calculation method of this kind of retaining structure is seldom studied. According to the pseudo-static method and the plastic limit analysis theory, the upper bound solutions are derived to calculate the seismic active earth pressure and its coefficient of three-stage retaining structures including gravity retaining wall and two-stage anchored retaining structures based on strength reduction technique. The following factors including horizontal and vertical seismic coefficients, the angle of the retaining wall back, slope surface shape and its multistage retaining structure, soil cohesion, adhesive strength between soil and retaining wall back are taken into account. The case study of two-step anchored retaining structures indicates that static active earth pressure agrees well with the available research;and the effects of the factors such as strength reduction

  10. Balancing priorities

    DEFF Research Database (Denmark)

    Mønsted, Troels; Johansen, Andreas Kaas; Lauridsen, Frederik Vahr Bjarnø

    2016-01-01

    a heterogeneous ensemble of care providers. In this paper, we present findings from a field study of coordinative work in distributed elder care in Denmark. The purpose of this study is to further our understanding of the coordinative challenges of distributed elder care, and to inform design of new care......, that are needed by the healthcare system, but also the work involved in balancing priorities....

  11. Lesson "Balance in Nature

    Science.gov (United States)

    Chapanova, V.

    2012-04-01

    Lesson "Balance in Nature" This simulation game-lesson (Balance in Nature) gives an opportunity for the students to show creativity, work independently, and to create models and ideas. It creates future-oriented thought connected to their experience, allowing them to propose solutions for global problems and personal responsibility for their activities. The class is divided in two teams. Each team chooses questions. 1. Question: Pollution in the environment. 2. Question: Care for nature and climate. The teams work on the chosen tasks. They make drafts, notes and formulate their solutions on small pieces of paper, explaining the impact on nature and society. They express their points of view using many different opinions. This generates alternative thoughts and results in creative solutions. With the new knowledge and positive behaviour defined, everybody realizes that they can do something positive towards nature and climate problems and the importance of individuals for solving global problems is evident. Our main goal is to recover the ecological balance, and everybody explains his or her own well-grounded opinions. In this work process the students obtain knowledge, skills and more responsible behaviour. This process, based on his or her own experience, dialogue and teamwork, helps the participant's self-development. Making the model "human↔ nature" expresses how human activities impact the natural Earth and how these impacts in turn affect society. Taking personal responsibility, we can reduce global warming and help the Earth. By helping nature we help ourselves. Teacher: Veselina Boycheva-Chapanova " Saint Patriarch Evtimii" Scholl Str. "Ivan Vazov"-19 Plovdiv Bulgaria

  12. 狭窄基坑平动模式刚性挡墙被动土压力分析%Study of passive earth pressures against translating rigid retaining walls in narrow excavations

    Institute of Scientific and Technical Information of China (English)

    应宏伟; 郑贝贝; 谢新宇

    2011-01-01

    对于地铁车站、地下管道沟槽等狭窄基坑,其被动区土体宽度有限,不满足半无限体的假定,采用经典的库仑、朗肯土压力理论计算挡墙被动土压力是不合适的.首先建立了无黏性土中狭窄基坑刚性挡墙的有限元分析模型,研究了挡墙相对平移时不同宽度土体的被动滑裂面的分布规律;借鉴库仑平面土楔假定,建立了狭窄基坑刚性平动挡墙被动土压力的理论计算模型,推导了被动极限状态下滑裂面倾角及被动土压力系数的解析公式;再采用水平薄层单元法,得到了被动土压力分布、土压力合力作用点高度的理论公式.结合算例,深入研究了这种工程背景下挡墙被动滑裂面倾角的影响因素,以及被动土压力合力、土压力分布及合力作用点位置与经典库仑土压力理论的差别,与数值计算结果的对比验证了该理论方法的合理性.研究发现,当被动区土体宽度小于满足半无限体的临界值、且墙土摩擦角大于0时,被动滑裂面倾角大于传统库仑被动滑裂面倾角,被动土压力大于经典库仑解,合力作用点高度则小于库仑解,且基坑越窄,墙土摩擦角越大,其差别越大.%For the case of narrow excavations such as subway stations and underground pipe, the width of the soil mass in passive zone is limited, so it's unsuitable to use the classical Coulomb or Rankine earth pressure theory to calculate the passive earth pressure. A finite element numerical model for retaining wall in narrow excavations is presented. The slip surfaces in the soils at passive limiting state with different widths of soils when the walls translating are investigated. Based on the concept of Coulomb sliding soil wedge, a new theoretical model for determining passive earth pressures against translating rigid retaining walls in narrow excavations is proposed. The formulae of the inclination angles of slip surfaces and coefficients of the resultant

  13. Lunar Balance and Locomotion

    Science.gov (United States)

    Paloski, William H.

    2008-01-01

    Balance control and locomotor patterns were altered in Apollo crewmembers on the lunar surface, owing, presumably, to a combination of sensory-motor adaptation during transit and lunar surface operations, decreased environmental affordances associated with the reduced gravity, and restricted joint mobility as well as altered center-of-gravity caused by the EVA pressure suits. Dr. Paloski will discuss these factors, as well as the potential human and mission impacts of falls and malcoordination during planned lunar sortie and outpost missions. Learning objectives: What are the potential impacts of postural instabilities on the lunar surface? CME question: What factors affect balance control and gait stability on the moon? Answer: Sensory-motor adaptation to the lunar environment, reduced mechanical and visual affordances, and altered biomechanics caused by the EVA suit.

  14. A hypothesis of earth quake

    CERN Document Server

    Tsai, Yeong-Shyeong

    2008-01-01

    Without a model, it is impossible for a geophysicist to study the possibility of forecasting earth quakes. In order to make a simple model, we make a hypothesis of earth quakes. The hypothesis is: (i) There are two kinds of earth quakes, one is the triggered breaking (earth quake), the other is spontaneous breaking (earth quake). (ii) Most major quakes in continental plates Eurasian Plate, North America Plate, South America Plate, Africa Plate and Australia Plate are triggered breaking. (iii) These triggered quakes are triggered by the movements of high pressure centers and low pressure centers of the atmosphere on continental plates. (iv) How can the movements of the high pressure centers trigger a quake? It depends on the extent of the high pressure center and the speed of the movement. Here, we stress high pressure center instead of low pressure center because it is dominated by high pressure center mostly. Of course, the boundary of the plates must have stored enough energy to have quakes, that is, near t...

  15. Social Balance Theory

    OpenAIRE

    Hokky Situngkir; Deni Khanafiah

    2004-01-01

    We construct a model based on social balance theory proposed by Fritz Heider to analyze the interpersonal network among social agents. The model of social balance theory provides us an interesting tool to see how a social group evolves to the possible balance state. We introduce the balance index that can be used to measure social balance in macro structure level (global balance index) or in micro structure (local balance index) to see how the local balance index influences the global balance...

  16. 考虑单元划分方式的平动挡墙主动土压力分析%Analysis of active earth pressure of considering translational unit modes for retaining wall

    Institute of Scientific and Technical Information of China (English)

    王梅; 侯新平; 李琦

    2015-01-01

    考虑平移模式下刚性挡土墙墙后填土中的土拱效应,分析沿圆弧形拱的切线和割线方向划分微分单元对主动土压力分布的影响。在此基础上,采用二分法求解最优划分方式,得到了作用在挡土墙上的主动土压力公式。与沿切线和割线方法及试验监测结果的对比分析表明:本文方法得到的平移模式下刚性挡墙墙后主动土压力强度小于沿切线划分单元的计算结果,略大于沿割线划分单元的计算值。本文方法得到的刚性挡墙墙后主动土压力分布与模型试验结果吻合最好。%Considering the soil-arching effect of retaining wall backfill of rigid translational mode , the pa-per analyzed the influence of division differential unit on along the arc arch tangent and secant .On above basis,it obtained the formula for the active earth pressure against a rigid retaining wall by means of di -chotomy to the optimum dipartition mode .Through comparing the formula with the theoretical solutions of tangent direction , secant direction and the results of measured test ,the result can be goten that the active earth pressure proposed is smaller than those of tangent direction and larger than those of secant direc -tion.The active earth pressure distribution of rigid wall backfill gotten by the method match best with the physical model test .

  17. From the Cover: Growth of Carnobacterium spp. from permafrost under low pressure, temperature, and anoxic atmosphere has implications for Earth microbes on Mars

    Science.gov (United States)

    Nicholson, Wayne L.; Krivushin, Kirill; Gilichinsky, David; Schuerger, Andrew C.

    2013-01-01

    The ability of terrestrial microorganisms to grow in the near-surface environment of Mars is of importance to the search for life and protection of that planet from forward contamination by human and robotic exploration. Because most water on present-day Mars is frozen in the regolith, permafrosts are considered to be terrestrial analogs of the martian subsurface environment. Six bacterial isolates were obtained from a permafrost borehole in northeastern Siberia capable of growth under conditions of low temperature (0 °C), low pressure (7 mbar), and a CO2-enriched anoxic atmosphere. By 16S ribosomal DNA analysis, all six permafrost isolates were identified as species of the genus Carnobacterium, most closely related to C. inhibens (five isolates) and C. viridans (one isolate). Quantitative growth assays demonstrated that the six permafrost isolates, as well as nine type species of Carnobacterium (C. alterfunditum, C. divergens, C. funditum, C. gallinarum, C. inhibens, C. maltaromaticum, C. mobile, C. pleistocenium, and C. viridans) were all capable of growth under cold, low-pressure, anoxic conditions, thus extending the low-pressure extreme at which life can function.

  18. Electrical resistivity and thermal conductivity of hcp Fe-Ni alloys under high pressure: Implications for thermal convection in the Earth's core

    Science.gov (United States)

    Gomi, Hitoshi; Hirose, Kei

    2015-10-01

    We measured the electrical resistivity of Fe-Ni alloys (iron with 5, 10, and 15 wt.% nickel) using four-terminal method in a diamond-anvil cell up to 70 GPa at 300 K. The results demonstrate that measured resistivity increases linearly with increasing nickel impurity concentration, as predicted by the Matthiessen's rule. The impurity resistivity is predominant at ambient temperature; the incorporation of 5 wt.% nickel into iron doubles the electrical resistivity at 60 GPa. Such impurity effect becomes minor at high temperature of the Earth's core because of the resistivity "saturation". We also calculated that >0.9 TW heat flow is necessary at the top of the inner core for thermal convection in the inner core. It requires the CMB heat flow of ∼30 TW, which is much higher than recent estimates of 5-15 TW. This means that purely thermal convection does not occur in the inner core.

  19. Earth\\'s Mass Variability

    CERN Document Server

    Mawad, Ramy

    2014-01-01

    The perturbation of the Earth caused by variability of mass of Earth as additional reason with gravity of celestial bodies and shape of the Earth. The Earth eating and collecting matters from space and loss or eject matters to space through its flying in the space around the Sun. The source of the rising in the global sea level is not closed in global warming and icebergs, but the outer space is the additional important source for this rising. The Earth eats waters from space in unknown mechanism. The mass of the Earth become greater in November i.e. before transit apoapsis two months, and become latter in February i.e. after transit apoapsis to two months.

  20. Solutions based on load balancing technology to the access pressure of network tasks%基于负载均衡技术的网络作业系统访问压力解决方案

    Institute of Scientific and Technical Information of China (English)

    于梅英; 张海波; 王春彦

    2011-01-01

    为解决网上作业系统访问压力与数据阻塞问题,提出了一种应用缓存技术、负载均衡技术的解决方案,并对网上作业系统的信息载入慢、服务器压力大、成绩试算次数过多3个关键问题设计了相应的解决算法.经兰州大学网络教育学院网上作业系统运行验证,表明实施解决方案后,能够有效地降低因访问过于集中而引起的网络阻塞和死锁问题,提高作业系统的稳定性和有效性.%In order to solve the problem of the high access pressure of network task system and data blocking, this article proposes solutions based on cache technology and load balancing technology,and a plan for solving three key problems: low speed of information load of network task system, high pressure of server and too many times of pilot calculation for scores. We also tested the network task system on the website of Lanzhou University Distance Education College. The result shows that applying it can effectively solve the problem of network being blocked or locked caused by excessive access so as to enhance the stability and effectiveness of the network task system.

  1. NON-LIMIT STATE EARTH PRESSURE AGAINST RETAINING WALL CONSIDERING INFLUENCE OF DEFORMATION%考虑变位影响的刚性挡墙非极限土压力研究

    Institute of Scientific and Technical Information of China (English)

    陈奕柏; 柯才桐; 高洪波; 陈云

    2015-01-01

    The classic theory of earth pressure can only be used to calculate the limit earth pressure on the retaining wall under the mode of translation. With the Mohr circle expressed with the principal stress difference and on the basis of the radial stress-strain relation obtained from the stress path triaxial tests,the nonlinear relationships of the mobilized internal friction angle of the soil and the friction angle between the wall and the backfill soils vesus the displacement were established under non-limit state. The method of effective area ratio of wall displacement was put forward to quantify the relationship to rigid retaining wall under the deformation mode of rotation. Based on the method above and combined with the method of horizontal slices and the modified Coulumb′s formula,the formula of earth pressure distribution,the resultant force and its application point under non-limit state which considered the influence of wall deformation were deduced. The result of an example showed that the difference between the theoretical calculation value quantified by the method of effective area ratio of displacement and the measured value was small. The proposed formula well reflects the change of earth pressure with the wall displacement and is an effective extension of Coulumb′s theoretical formula.%经典土压力理论仅能计算平移模式挡墙的极限状态土压力。采用以主应力差表示的应力圆,根据应力路径三轴试验中得到的径向应力–应变关系,建立非极限状态下受位移影响的土体内摩擦角、墙土间摩擦角发挥值随位移的变化关系,并提出有效位移面积比方法将该关系量化至转动变位模式挡墙。在此基础上,应用水平层分析法和改进的库仑公式,推导出考虑挡墙变位影响的非极限土压力合力及其作用点位置、土压力分布计算式。研究表明:按有效位移面积比方法进行量化后,理论计算值与实测值相对误差

  2. Relevance of balance measurement tools and balance training for fall prevention in older adults

    Directory of Open Access Journals (Sweden)

    Majumi M. Noohu, MPTh

    2014-06-01

    Full Text Available Approximately one in three older people fall each year owing to gait/balance disorder/weakness, the second leading cause of falls in older adults. This review evaluates the capability of different balance measurement tools to predict falls in the elderly, which are used routinely for assessing balance impairment. Balance measurement tools reviewed are the Timed Up and Go test, Berg Balance Scale, Tinetti Performance Oriented Mobility Assessment, Functional Reach Test, Clinical Test of Sensory Integration for Balance, and the postural sway measurements or center of pressure. The effect of balance training on the postural control mechanism and its efficacy in fall prevention in older adults were also reviewed. The current evidence is not conclusive enough to favor existing balance measurement tools and balance training implemented for fall prevention in older adults.

  3. Ab initio MD simulations of Mg2SiO4 liquid at high pressures and temperatures relevant to the Earth's mantle

    Science.gov (United States)

    Martin, G. B.; Kirtman, B.; Spera, F. J.

    2010-12-01

    Computational studies implementing Density Functional Theory (DFT) methods have become very popular in the Materials Sciences in recent years. DFT codes are now used routinely to simulate properties of geomaterials—mainly silicates and geochemically important metals such as Fe. These materials are ubiquitous in the Earth’s mantle and core and in terrestrial exoplanets. Because of computational limitations, most First Principles Molecular Dynamics (FPMD) calculations are done on systems of only 100 atoms for a few picoseconds. While this approach can be useful for calculating physical quantities related to crystal structure, vibrational frequency, and other lattice-scale properties (especially in crystals), it would be useful to be able to compute larger systems especially for extracting transport properties and coordination statistics. Previous studies have used codes such as VASP where CPU time increases as N2, making calculations on systems of more than 100 atoms computationally very taxing. SIESTA (Soler, et al. 2002) is a an order-N (linear-scaling) DFT code that enables electronic structure and MD computations on larger systems (N 1000) by making approximations such as localized numerical orbitals. Here we test the applicability of SIESTA to simulate geosilicates in the liquid and glass state. We have used SIESTA for MD simulations of liquid Mg2SiO4 at various state points pertinent to the Earth’s mantle and congruous with those calculated in a previous DFT study using the VASP code (DeKoker, et al. 2008). The core electronic wave functions of Mg, Si, and O were approximated using pseudopotentials with a core cutoff radius of 1.38, 1.0, and 0.61 Angstroms respectively. The Ceperly-Alder parameterization of the Local Density Approximation (LDA) was used as the exchange-correlation functional. Known systematic overbinding of LDA was corrected with the addition of a pressure term, P 1.6 GPa, which is the pressure calculated by SIESTA at the experimental

  4. Balanced Flow Meters without Moving Parts

    Science.gov (United States)

    Kelley, Anthony R.; VanBuskirk, Paul

    2008-01-01

    Balanced flow meters are recent additions to an established class of simple, rugged flow meters that contain no moving parts in contact with flow and are based on measurement of pressure drops across objects placed in flow paths. These flow meters are highly accurate, minimally intrusive, easily manufacturable, and reliable. A balanced flow meter can be easily mounted in a flow path by bolting it between conventional pipe flanges. A balanced flow meter can be used to measure the flow of any of a variety of liquids or gases, provided that it has been properly calibrated. Relative to the standard orifice-plate flow meter, the balanced flow meter introduces less turbulence and two times less permanent pressure loss and is therefore capable of offering 10 times greater accuracy and repeatability with less dissipation of energy. A secondary benefit of the reduction of turbulence is the reduction of vibration and up to 15 times less acoustic noise generation. Both the balanced flow meter and the standard orifice-plate flow meter are basically disks that contain holes and are instrumented with pressure transducers on their upstream and downstream faces. The most obvious difference between them is that the standard orifice plate contains a single, central hole while the balanced flow meter contains multiple holes. The term 'balanced' signifies that in designing the meter, the sizes and locations of the holes are determined in an optimization procedure that involves balancing of numerous factors, including volumetric flow, mass flow, dynamic pressure, kinetic energy, all in an effort to minimize such undesired effects as turbulence, pressure loss, dissipation of kinetic energy, and non-repeatability and nonlinearity of response over the anticipated range of flow conditions. Due to proper balancing of these factors, recent testing demonstrated that the balanced flow-meter performance was similar to a Venturi tube in both accuracy and pressure recovery, but featured reduced

  5. Approximately-Balanced Drilling in Daqing Oilfield

    Institute of Scientific and Technical Information of China (English)

    Xia Bairu; Zheng Xiuhua; Li Guoqing; Tian Tuo

    2004-01-01

    The Daqing oilfield is a multilayered heterogeneous oil field where the pressure are different in the same vertical profile causing many troubles to the adjustment well drillings. The approximately-balanced drilling technique has been developed and proved to be efficient and successful in Daqing oilfield. This paper discusses the application of approximately-balanced drilling technique under the condition of multilayered pressure in Daqing oilfield, including the prediction of formation pressure, the pressure discharge technique for the drilling well and the control of the density of drilling fluid.

  6. The Global Challenge: A Matter of Balance.

    Science.gov (United States)

    Mulford, Bill

    2002-01-01

    Argues that global challenge created by the pressure for change requires educators to understand the balance between continuity and constant change dependence and independence, individualism and community, homogeneity and heterogeneity. To achieve balanced learning and development, education should place greater emphasis on continuity,…

  7. Ce{sub 2}B{sub 8}O{sub 15}. High-pressure synthesis and crystal structure determination of a rare-earth polyborate exhibiting a new 'Fundamental Building Block'

    Energy Technology Data Exchange (ETDEWEB)

    Glaetzle, Matthias; Heymann, Gunter; Huppertz, Hubert [Innsbruck Univ. (Austria). Inst. fuer Allgemeine, Anorganische und Theoretische Chemie

    2013-10-01

    The new cerium polyborate Ce{sub 2}B{sub 8}O{sub 15} was synthesized under high-pressure/high-temperature conditions of 6 GPa and 1050 C in a Walker-type multianvil apparatus. The single-crystal structure determination revealed that the new compound crystallizes in the space group P2/c with the lattice parameters a = 916.6(2), b = 421.0(1), c = 1248.9(3) pm, {beta} = 116.7(1) , V = 0.4303(2) nm{sup 3}, R1 = 0.0356, and wR2 = 0.0504. The crystal structure of Ce{sub 2}B{sub 8}O{sub 15} exhibits a new fundamental building block (FBB) in borate chemistry that consists of four BO{sub 4} tetrahedra and can be written as 4{open_square}: [{Phi}] left angle 3{open_square} right angle vertical stroke {open_square} vertical stroke. These FBB are interconnected via common corners, forming a complex threedimensional network that contains the Ce{sup 3+} cations. Ce{sub 2}B{sub 8}O{sub 15} represents the most boron rich rare-earth borate synthesized under high-pressure/high-temperature conditions so far. We report about the synthetic conditions, structural details, thermal behaviour, and the IR/Raman spectra of Ce{sub 2}B{sub 8}O{sub 15}. (orig.)

  8. Análise da pressão plantar e do equilíbrio postural em diferentes fases da gestação Analysis of plantar pressure and postural balance during different phases of pregnancy

    Directory of Open Access Journals (Sweden)

    SI Ribas

    2007-10-01

    Full Text Available OBJETIVO: Analisar a pressão plantar e o equilíbrio postural nos três trimestres de gravidez, bem como a correlação com as características antropométricas. METODOLOGIA: 60 voluntárias com idade média de 23,3 ± 5,5 anos, sendo 15 mulheres em cada grupo: não-gestantes (C, primeiro (1T, segundo (2T e terceiro trimestre (3T. A avaliação foi efetuada por meio de plataforma de pressão na posição bipodal com os olhos abertos. As variáveis analisadas nos pés direito e esquerdo foram: pico de pressão em todo o pé (PT, no antepé (PA e no retropé (PR; distância entre a borda medial dos pés (largura da base de suporte; distância do centro de força ao limite anterior (CFF e posterior (CFC dos pés; deslocamento ântero-posterior (AP e médio--lateral (ML do centro de força; e área de contato (AC. RESULTADOS: Não houve diferença no pico de pressão de contato e na distância CFF e CFC entre os grupos. O deslocamento AP foi maior (p 0,05 entre os grupos para o deslocamento ML. Houve correlação positiva entre peso ganho durante a gestação com AC para o grupo 2T e com PT no pé direito do grupo 1T. CONCLUSÃO: Os resultados demonstram a influência das mudanças anatômicas e fisiológicas inerentes à gestação na pressão plantar, além de sugerir uma redução do equilíbrio postural no 3T, relacionada ao maior deslocamento AP nessa fase.OBJECTIVE: To analyze plantar pressure and postural balance during the three trimesters of pregnancy, and also to correlate these with anthropometric characteristics. METHOD: Sixty volunteers participated in this study, with a mean age of 23.3 ± 5.5 years. There were 15 subjects in each group: non-pregnant (C, first trimester (1T, second trimester (2T and third trimester (3T. Evaluations were performed in bipedal stance with open eyes, using a pressure platform. The following variables were analyzed in the right and left feet: peak pressures in the whole foot (WFP, forefoot (FFP and

  9. 电动可调式动态流量平衡阀和末端电动调节定压差阀结合的水力平衡与控制策略%Hydraulic balance and control strategy of combination control system of electric adjustable dynamic balancing valve and terminal electric constant pressure valve

    Institute of Scientific and Technical Information of China (English)

    孙晋飞; 郭健翔; 沈聪; 李林

    2012-01-01

    分析了集中空调系统水力失调的原因和解决措施,通过比较末端恒压差控制系统和应用电动可调式动态流量平衡阀的控制系统的控制原理以及变流量条件下的能耗高低,研究了这两个控制系统对管网中调节阀流量特性曲线的影响,具体分析了设备效率对系统性能的影响.%Examines the cause and solutions of hydraulic disorder of central air conditioning systems. According to the comparison of control principle and energy consumption under variable flow rate condition between the end constant pressure difference control system and the control system with electric adjustable dynamic balancing valve, studies the influence of the two control systems on the flow characteristic curve of the electric control valve, and analyses the influence of equipment efficiency on the performance of the system in detail.

  10. Major Element Compositions and Rare—earth Element Abundaces of Cenozoic Basalts in Eastern China:Implications for a Pressure Control over LREE/HREE Fractionation in Continental Basalt

    Institute of Scientific and Technical Information of China (English)

    刘丛强; AKIMASAMASUDA; 等

    1992-01-01

    Major element compositions and rare-earth element (REE) and transition element(Ni,Cr and V) abundances have been determined on 44 basalt samples from eastern China.These basalts have SiO2 contents ranging from 38.63 to 55.24(wt.%),and Na2O+K2O from 3.1 to 9.4(wt.%).Ni and Cr abundances are largely variable,respectively falling in ranges 60-605 and 78-1150 ppm.REE abundances,especially light rare-earth elements(LREE), are highly variable.La/Sm and La/Yb ratios vary 2.8 to 7.6 and 1.8 to 8.1. Although the segregation mainly of olivine and clinopyroxene is requested to account for the vari-able and low MgO,CaO/Al2O3,Cr and Ni characteristic of these basalts studied here,the differ-ences in REE composition of the basalts are still related mainly to the partial melting process.Obvious varations in REE abundances could be principally attributed to the partial melting process.Obvious variations in REE abundances could be principally attributed to the partial melting processes that took place at different depths,in spite of some variations caused by the fractional crystallization processes.REE abundances and La/Sm and La/Yb ratios systematically decrease with increasing SiO2,which probably indicated that the basaltic magma derived from a deeper level has higher LREE and LREE/HREE ratios than that from a shallower level.As viewed from the fact that the DYb/DLa ratios of clinopyroxenes in the basaltic system increase with increasing pressure,the increase of LREE/HUEE ratios with increasing melting depth can be interpreted as the pressure dependence of bulk DHREE/DLREE ratios of silicate minerals,in addition to the pressure control over the melting degree.

  11. Approaching a realistic force balance in geodynamo simulations.

    Science.gov (United States)

    Yadav, Rakesh K; Gastine, Thomas; Christensen, Ulrich R; Wolk, Scott J; Poppenhaeger, Katja

    2016-10-25

    Earth sustains its magnetic field by a dynamo process driven by convection in the liquid outer core. Geodynamo simulations have been successful in reproducing many observed properties of the geomagnetic field. However, although theoretical considerations suggest that flow in the core is governed by a balance between Lorentz force, rotational force, and buoyancy (called MAC balance for Magnetic, Archimedean, Coriolis) with only minute roles for viscous and inertial forces, dynamo simulations must use viscosity values that are many orders of magnitude larger than in the core, due to computational constraints. In typical geodynamo models, viscous and inertial forces are not much smaller than the Coriolis force, and the Lorentz force plays a subdominant role; this has led to conclusions that these simulations are viscously controlled and do not represent the physics of the geodynamo. Here we show, by a direct analysis of the relevant forces, that a MAC balance can be achieved when the viscosity is reduced to values close to the current practical limit. Lorentz force, buoyancy, and the uncompensated (by pressure) part of the Coriolis force are of very similar strength, whereas viscous and inertial forces are smaller by a factor of at least 20 in the bulk of the fluid volume. Compared with nonmagnetic convection at otherwise identical parameters, the dynamo flow is of larger scale and is less invariant parallel to the rotation axis (less geostrophic), and convection transports twice as much heat, all of which is expected when the Lorentz force strongly influences the convection properties.

  12. High-pressure, temperature elasticity of Fe- and Al-bearing MgSiO3: implications for the Earth's lower mantle

    CERN Document Server

    Zhang, Shuai; Liu, Tao; Stackhouse, Stephen; Militzer, Burkhard

    2015-01-01

    Fe and Al are two of the most important rock-forming elements other than Mg, Si, and O. Their presence in the lower mantle's most abundant minerals, MgSiO_3 bridgmanite, MgSiO_3 post-perovskite and MgO periclase, alters their elastic properties. However, knowledge on the thermoelasticity of Fe- and Al-bearing MgSiO_3 bridgmanite, and post-perovskite is scarce. In this study, we perform ab initio molecular dynamics to calculate the elastic and seismic properties of pure, Fe^{3+}- and Fe^{2+}-, and Al^{3+}-bearing MgSiO_3 perovskite and post-perovskite, over a wide range of pressures, temperatures, and Fe/Al compositions. Our results show that a mineral assemblage resembling pyrolite fits a 1D seismological model well, down to, at least, a few hundred kilometers above the core-mantle boundary, i.e. the top of the D'' region. In D'', a similar composition is still an excellent fit to the average velocities and fairly approximate to the density. We also implement polycrystal plasticity with a geodynamic model to ...

  13. Using earth-tide induced water pressure changes to measure in situ permeability: A comparison with long-term pumping tests

    Science.gov (United States)

    Allègre, Vincent; Brodsky, Emily E.; Xue, Lian; Nale, Stephanie M.; Parker, Beth L.; Cherry, John A.

    2016-04-01

    Good constraints on hydrogeological properties are an important first step in any quantitative model of groundwater flow. Field estimation of permeability is difficult as it varies over orders of magnitude in natural systems and is scale-dependent. Here we directly compare permeabilities inferred from tidal responses with conventional large-scale, long-term pumping tests at the same site. Tidally induced water pressure changes recorded in wells are used to infer permeability at ten locations in a densely fractured sandstone unit. Each location is either an open-hole well or a port in a multilevel monitoring well. Tidal response is compared at each location to the results of two conventional, long-term and large scale pumping tests performed at the same site. We obtained consistent values between the methods for a range of site-specific permeabilities varying from ˜10-15 m2 to 10-13 m2 for both open wells with large open intervals and multilevel monitoring well. We conclude that the tidal analysis is able to capture passive and accurate estimates of permeability.

  14. Research and practice of water pressure balance and purification system in underwater protection works of White Crane Ridge Inscription%白鹤梁水下保护工程平压净水系统研究与实践

    Institute of Scientific and Technical Information of China (English)

    王环武; 韩建成; 龚斌

    2014-01-01

    三峡库区的白鹤梁水下题刻保护工程采用“无压容器”的概念建造,实现该原理的关键设备为平压净水系统。通过选择廊道输水方式,并设计合理的水压平衡程序、充水置换程序、封闭循环程序等,实现了保护体内外水压差基本为零,且水的浊度始终达标。该系统已安全运行5 a,从而证明前期的设计思路、方法及模拟试验成果均是可行和可靠的。%The concept of "non-pressure vessel" was adopted to build the underwater protection works of White Crane Ridge Inscription, and the water pressure balance and purification system is a key equipment. For realizing balance of water pressure in the protection works and maintaining of water clear, a corridor water transferring solution is adopted, and several procedures are designed, including pressure balance procedure, water filling and replacement procedure, closed cycle procedure, et al. The system has been operated safely for 5 years, so it verifies the correctness and reliability of the previous design ideas, methodology as well as simulation tests.

  15. An Analog Earth Climate Model

    Science.gov (United States)

    Varekamp, J. C.

    2010-12-01

    experiment. For each time increment the radiative heat loss of the sphere is calculated from the Stefan Boltzman expression using the observed temperature at that time. The heating of the ‘earth sphere’ is accounted for in the energy balance equation by applying the temperature increase per time increment with the specific heat of bronze. The remaining energy term is the sum of the convective cooling and greenhouse effect. The heat budgets of the cooling trajectories were calculated analogous, with radiative and convective cooling causing the temperature drop per time increment. The greenhouse component again is lumped with the convective term. Equilibrium temperatures of 50-70 C were reached, with ambient temperature at 22 C. Somewhat surprising, experiments with radiatively neutral pure Argon gas yielded the highest equilibrium temperatures. Argon had the lowest specific heat of the gases used, and the observed equilibrium temperatures for different cell gases broadly scaled inversely with the heat capacity of those gases. Apparently, the efficiency of the free convective cooling strongly impacts the equilibrium temperatures. The greenhouse effects possibly have only a minor impact on final temperature as a result of the short cell pathlength. Experiments at higher cell filling pressures may provide more insight in this.

  16. THE COSMIC-RAY INTENSITY NEAR THE ARCHEAN EARTH

    Energy Technology Data Exchange (ETDEWEB)

    Cohen, O.; Drake, J. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St., Cambridge, MA 02138 (United States); Kota, J. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721-0092 (United States)

    2012-11-20

    We employ three-dimensional state-of-the-art magnetohydrodynamic models of the early solar wind and heliosphere and a two-dimensional model for cosmic-ray transport to investigate the cosmic-ray spectrum and flux near the Archean Earth. We assess how sensitive the cosmic-ray spectrum is to changes in the sunspot placement and magnetic field strength, the large-scale dipole magnetic field strength, the wind ram pressure, and the Sun's rotation period. Overall, our results confirm earlier work that suggested the Archean Earth would have experienced a greatly reduced cosmic-ray flux than is the case today. The cosmic-ray reduction for the early Sun is mainly due to the shorter solar rotation period and tighter winding of the Parker spiral, and to the different surface distribution of the more active solar magnetic field. These effects lead to a global reduction of the cosmic-ray flux at 1 AU by up to two orders of magnitude or more. Variations in the sunspot magnetic field have more effect on the flux than variations in the dipole field component. The wind ram pressure affects the cosmic-ray flux through its influence on the size of the heliosphere via the pressure balance with the ambient interstellar medium. Variations in the interstellar medium pressure experienced by the solar system in orbit through the Galaxy could lead to order of magnitude changes in the cosmic-ray flux at Earth on timescales of a few million years.

  17. Runoff, precipitation, mass balance, and ice velocity measurements at South Cascade Glacier, Washington, 1993 balance year

    Science.gov (United States)

    Krimmel, R.M.

    1994-01-01

    Winter snow accumulation and summer snow, firn, and ice ablation were measured at South Cascade Glacier, Wash., to determine the winter and net balance for the 1993 balance year. The 1993 winter balance, averaged over the glacier, was 1.98 meters, and the net balance was -1.23 meters. This negative valance continued a trend of negative balance years beginning in 1977. Air temperature, barometric pressure, and runoff from this glacier basin and an adjacent non-glacierized basin were also continuously measured. Surface ice velocity was measured over an annual period. This report makes all these data available to users throughout the glaciological and climato1ogical community.

  18. 基于非线性破坏准则的挡土墙被动土压力上限分析%Upper Bound Solutions for Passive Earth Pressure of Retaining Wall Basedon Nonlinear Failure Criterion

    Institute of Scientific and Technical Information of China (English)

    李丽民; 张国祥; 王恭兴

    2011-01-01

    传统的挡土墙土压力计算基于Mohr-Coulomb线性破坏准则,但大量试验数据表明,土体破坏时最大主应力和最小主应力的关系是非线性的.为此,基于Mohr-Coulomb非线性破坏准则,将挡土墙后填土划分为多个刚性滑块组成的破坏机构,根据极限分析中的上限理论建立容许的速度场.根据岩土实际应力情况,不同边界采用不同的切线强度计算参数,提出一种“多切线法”,推导得出挡土墙被动土压力的解析表达式,通过大型数学规划理论优化得到最优上限解.计算结果表明:当非线性破坏准则变为线性破坏准则时,结果与前人成果一致;非线性参数m、超载q、初始黏结力C0对被动土压力有重要影响;与单切线法相比,采用多切线法理论上更加严密,计算结果更接近真实值,具有较高的实用价值.%Conventional calculations of earth pressure for retaining walls are made in terms of the linear Mohr-Coulomb (MC) failure criterion. However, a substantial amount of experimental data shows that the relationship between the first principal stress and the third principal stress is nonlinear when soil is broken. Therefore, based on the Mohr-Coulomb nonlinear failure criterion and the multi-wedge translation failure mechanism, considering the effect of normal stress distribution on the cohesion and the internal friction angle, giving different boundary surfaces to different cohesion and internal friction angle, by the optimization theory, the multi-tangential technique is used to deduce the passive earth pressures of retaining walls. The minimum solution is obtained by optimization. From the calculation results, it can be seen that if the nonlinear Mohr-Coulomb yield criterion turns into the linear Mohr-Coulomb yield criterion, then the solutions presented in this paper agree well with the chen and soubra research conclusions, and the nonlinear parameter, overloading and initial cohesion have significant

  19. Snowball Earth

    OpenAIRE

    2016-01-01

    In the ongoing quest to better understand where life may exist elsewhere in the Universe, important lessons may be gained from our own planet. In particular, much can be learned from planetary glaciation events that Earth suffered ∼600 million years ago, so-called `Snowball Earth' episodes. I begin with an overview of how the climate works. This helps to explain how the ice-albedo feedback effect can destabilise a planet's climate. The process relies on lower temperatures causing more ice to ...

  20. A Balancing Act: A Quantitative Analysis of the Influence of Work/Life Balance and Work Atmosphere on Personal and Professional Success of Women Scientists

    Science.gov (United States)

    Archie, T.; Laursen, S. L.; Kogan, M.

    2012-12-01

    Despite an increase in advanced degrees awarded to women in the geosciences, scientific leaders in academia remain dominantly male. Women are underrepresented in tenure-track positions in Earth science departments at research universities and are less likely to have more senior positions within their academic institutions. Our empirical study analyzes factors that influence personal and professional success for women scientists. Prior research has shown that women are subjected to unintended and unrecognized biases that can have an ultimate impact on their productivity, advancement, and success. We used an electronic survey to collect data from 662 early-career geoscientists who are members of the Earth Science Women's Network and/or the network's Earth Science Jobs list. We asked respondents to self-report their perceptions of work/life balance, professional atmosphere and other variables indicative and/or predictive of personal and professional success. In a previous analysis (Kogan & Laursen, 2011) we found that women consistently rated the professional atmosphere in their departments and their interactions with colleagues less favorably than men. Women indicated lower rates of collaboration with colleagues in their unit compared to their male peers. We also found work/life balance is of particular concern to early-career scientists, especially since tenure clock and the biological clock function on similar timetables. Women reported more caregiving responsibilities than men, further complicating the balance between work and personal life. We hypothesize that the work life balance and professional atmosphere influences productivity, advancement, and career/job satisfaction. We now investigate how work/life balance, atmosphere within the work unit, and mentoring influence productivity, job and career satisfaction, and career advancement. We introduce a structural equation model that seeks to explain how these relationships vary dependent upon gender, career level

  1. Dizziness and Balance

    Science.gov (United States)

    AUDIOLOGY Dizziness and Balance Inform ation Seri es Our balance system helps us walk, run, and move without falling. ... if I have a problem with balance or dizziness? It is important to see your doctor if ...

  2. Digital Earth - A sustainable Earth

    Science.gov (United States)

    Mahavir

    2014-02-01

    All life, particularly human, cannot be sustainable, unless complimented with shelter, poverty reduction, provision of basic infrastructure and services, equal opportunities and social justice. Yet, in the context of cities, it is believed that they can accommodate more and more people, endlessly, regardless to their carrying capacity and increasing ecological footprint. The 'inclusion', for bringing more and more people in the purview of development is often limited to social and economic inclusion rather than spatial and ecological inclusion. Economic investment decisions are also not always supported with spatial planning decisions. Most planning for a sustainable Earth, be at a level of rural settlement, city, region, national or Global, fail on the capacity and capability fronts. In India, for example, out of some 8,000 towns and cities, Master Plans exist for only about 1,800. A chapter on sustainability or environment is neither statutorily compulsory nor a norm for these Master Plans. Geospatial technologies including Remote Sensing, GIS, Indian National Spatial Data Infrastructure (NSDI), Indian National Urban Information Systems (NUIS), Indian Environmental Information System (ENVIS), and Indian National GIS (NGIS), etc. have potential to map, analyse, visualize and take sustainable developmental decisions based on participatory social, economic and social inclusion. Sustainable Earth, at all scales, is a logical and natural outcome of a digitally mapped, conceived and planned Earth. Digital Earth, in fact, itself offers a platform to dovetail the ecological, social and economic considerations in transforming it into a sustainable Earth.

  3. Definition of Coefficient of Earth Pressure and Methods Review%土体静止侧压力系数定义及其确定方法综述

    Institute of Scientific and Technical Information of China (English)

    王俊杰; 郝建云

    2013-01-01

    Based on comparing the differences of definition of coefficient earth pressure (K0) with total stress method,effective stress method and effective stress increment method,the current status of main influencing factors are briefly described,which includes soil physical property,stress history,soil structure,soil sample by the degree of disturbance,pore water pressure and the degree of soil consolidation.Advance of studies on method of determination the coefficient K0 are summarized,that is laboratory experiment,in-situ test,empirical formula,constitutive models and numerical simulation test.So,it provides references for deeply study of the coefficient K0 in the future.%在比较总应力法、有效应力法、有效应力增量法的静止土侧压力(K0)系数定义差异基础上,简述了影响K0系数的主要影响因素(如物理力学性质、应力历史、土体结构、土样受扰动程度、孔隙水压力、土体固结程度)的研究现状,综述了室内试验、原位测试试验、经验公式、本构模型、数值仿真试验确定K0系数的方法的研究进展,可为未来K0系数的深入研究提供借鉴.

  4. Water and sodium balance in space

    DEFF Research Database (Denmark)

    Drummer, C; Norsk, P; Heer, M

    2001-01-01

    We have previously shown that fluid balances and body fluid regulation in microgravity (microG) differ from those on Earth (Drummer et al, Eur J Physiol 441:R66-R72, 2000). Arriving in microG leads to a redistribution of body fluid-composed of a shift of fluid to the upper part of the body and an...

  5. Postural sway parameters in seated balancing; their reliability and relationship with balancing performance

    NARCIS (Netherlands)

    Dieën, J.H. van; Koppes, L.L.J.; Twisk, J.W.R.

    2010-01-01

    This study investigated a representative set of 39 parameters characterizing center of pressure movements (sway) in seated balancing, with the aims to determine test-retest reliability, to clarify the interrelations between these parameters, and to determine which parameters were related to balance

  6. Temperature of Earth's core constrained from melting of Fe and Fe0.9Ni0.1 at high pressures

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Dongzhou; Jackson, Jennifer M.; Zhao, Jiyong; Sturhahn, Wolfgang; Alp, E. Ercan; Hu, Michael Y.; Toellner, Thomas S.; Murphy, Caitlin A.; Prakapenka, Vitali B.

    2016-08-01

    The melting points of fcc- and hcp-structured Fe0.9Ni0.1 and Fe are measured up to 125 GPa using laser heated diamond anvil cells, synchrotron Mossbauer spectroscopy, and a recently developed fast temperature readout spectrometer. The onset of melting is detected by a characteristic drop in the time integrated synchrotron Mfissbauer signal which is sensitive to atomic motion. The thermal pressure experienced by the samples is constrained by X-ray diffraction measurements under high pressures and temperatures. The obtained best-fit melting curves of fcc-structured Fe and Fe0.9Ni0.1 fall within the wide region bounded by previous studies. We are able to derive the gamma-is an element of-1 triple point of Fe and the quasi triple point of Fe0.9Ni0.1 to be 110 ± 5 GPa, 3345 ± 120 K and 116 ± 5 GPa, 3260 ± 120 K, respectively. The measured melting temperatures of Fe at similar pressure are slightly higher than those of Fe0.9Ni0.1 while their one sigma uncertainties overlap. Using previously measured phonon density of states of hcp-Fe, we calculate melting curves of hcp-structured Fe and Fe0.9Ni0.1 using our (quasi) triple points as anchors. The extrapolated Fe0.9Ni0.1 melting curve provides an estimate for the upper bound of Earth's inner core-outer core boundary temperature of 5500 ± 200 K. The temperature within the liquid outer core is then approximated with an adiabatic model, which constrains the upper bound of the temperature at the core side of the core -mantle boundary to be 4000 ± 200 K. We discuss a potential melting point depression caused by light elements and the implications of the presented core -mantle boundary temperature bounds on phase relations in the lowermost part of the mantle.

  7. Determining Atmospheric Pressure Using a Water Barometer

    Science.gov (United States)

    Lohrengel, C. Frederick, II; Larson, Paul R.

    2012-01-01

    The atmosphere is an envelope of compressible gases that surrounds Earth. Because of its compressibility and nonuniform heating by the Sun, it is in constant motion. The atmosphere exerts pressure on Earth's surface, but that pressure is in constant flux. This experiment allows students to directly measure atmospheric pressure by measuring the…

  8. Balance in Assessment

    Science.gov (United States)

    White, Richard

    2007-01-01

    The review by Black and Wiliam of national systems makes clear the complexity of assessment, and identifies important issues. One of these is "balance": balance between local and central responsibilities, balance between the weights given to various purposes of schooling, balance between weights for various functions of assessment, and balance…

  9. A reconciled estimate of ice-sheet mass balance

    DEFF Research Database (Denmark)

    Shepherd, Andrew; Ivins, Erik R; A, Geruo;

    2012-01-01

    We combined an ensemble of satellite altimetry, interferometry, and gravimetry data sets using common geographical regions, time intervals, and models of surface mass balance and glacial isostatic adjustment to estimate the mass balance of Earth's polar ice sheets. We find that there is good...

  10. 地铁区间隧道穿越粉细砂地层土压平衡盾构施工技术%Earth-Pressure-Balanced Shield Construction Techniques for Subway Tunnels in the Fine Sand Stratum

    Institute of Scientific and Technical Information of China (English)

    肖昱

    2015-01-01

    石家庄市城市轨道交通1号线体育场站~北宋站区间隧道穿越粉细砂地层,施工采用土压平衡盾构掘进技术,对始发洞口进行了双管旋喷桩加固,掘进过程中优化了盾构推进速度、土仓压力、出土量、推力及注浆压力等主要技术参数,保证了施工安全,区间隧道顺利贯通;采用同步注浆和二次注浆措施及优化的掘进施工参数控制了掌子面的稳定和地表沉降.工程实践证明土压平衡盾构也适用于粉细砂地层的区间隧道施工.

  11. Construction Technology of Earth Pressure Balance Shield in the Whole Section Hard Rock Layer%土压平衡盾构全断面硬岩施工技术

    Institute of Scientific and Technical Information of China (English)

    闫建诚

    2014-01-01

    盾构隧道开挖断面范围为硬岩地层时,存在盾构掘进速度慢、盾构姿态控制难度大、设备及刀具磨损严重且刀具更换频繁等问题。结合实际工程,介绍了盾构选型、掘进模式选择、盾构掘进参数和盾构姿态控制、刀具管理等关键措施,确保盾构安全顺利推进。%There are some difficulties when tunnel section locating in weathered hard rock stratum such as slow tunneling speed, difficulties in controlling shield posture, equipment and serious tool wearing and frequent tools replacing. Based on actual project, key measures are introduced to ensure the safety and successful shield construction including choosing the reasonable selection of shield and driving mode, strictly controlling of shield tunneling parameters and shield posture, and strengthening shield tools management.

  12. Funing Rare Earths Industrial Co. Ltd

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    The company covers separation with whole lines of light, medium and heavy rare earths, with annual separation volume of rare earth oxides of 4,500 tons. It also produces rare earth oxides, fluorides and salts. Products with high-purity and super-high-purity are produced according to customer's request. Under the technological guidance of domestic experts and application of modern high-pressure

  13. Plant adaptation to low atmospheric pressures: potential molecular responses

    Science.gov (United States)

    Ferl, Robert J.; Schuerger, Andrew C.; Paul, Anna-Lisa; Gurley, William B.; Corey, Kenneth; Bucklin, Ray

    2002-01-01

    There is an increasing realization that it may be impossible to attain Earth normal atmospheric pressures in orbital, lunar, or Martian greenhouses, simply because the construction materials do not exist to meet the extraordinary constraints imposed by balancing high engineering requirements against high lift costs. This equation essentially dictates that NASA have in place the capability to grow plants at reduced atmospheric pressure. Yet current understanding of plant growth at low pressures is limited to just a few experiments and relatively rudimentary assessments of plant vigor and growth. The tools now exist, however, to make rapid progress toward understanding the fundamental nature of plant responses and adaptations to low pressures, and to develop strategies for mitigating detrimental effects by engineering the growth conditions or by engineering the plants themselves. The genomes of rice and the model plant Arabidopsis thaliana have recently been sequenced in their entirety, and public sector and commercial DNA chips are becoming available such that thousands of genes can be assayed at once. A fundamental understanding of plant responses and adaptation to low pressures can now be approached and translated into procedures and engineering considerations to enhance plant growth at low atmospheric pressures. In anticipation of such studies, we present here the background arguments supporting these contentions, as well as informed speculation about the kinds of molecular physiological responses that might be expected of plants in low-pressure environments.

  14. Space vehicle with artificial gravity and earth-like environment

    Science.gov (United States)

    Gray, V. H. (Inventor)

    1973-01-01

    A space vehicle adapted to provide an artificial gravity and earthlike atmospheric environment for occupants is disclosed. The vehicle comprises a cylindrically shaped, hollow pressure-tight body, one end of which is tapered from the largest diameter of the body, the other end is flat and transparent to sunlight. The vehicle is provided with thrust means which rotates the body about its longitudinal axis, generating an artificial gravity effect upon the interior walls of the body due to centrifugal forces. The walls of the tapered end of the body are maintained at a temperature below the dew point of water vapor in the body and lower than the temperature near the transparent end of the body. The controlled environment and sunlight permits an earth like environment to be maintained wherein the CO2/O2 is balanced, and food for the travelers is supplied through a natural system of plant life grown on spacecraft walls where soil is located.

  15. 节律性压力波对家犬气道黏蛋白分泌平衡的影响及其机制%Effect of rhythmic pressure waves on balancing airway basic mucus secretion in dogs

    Institute of Scientific and Technical Information of China (English)

    刘诗兰; 尤列·皮尔曼; 维克多·科罗索夫; 周向东

    2013-01-01

    group C:the tension-sensitive cation channel (TRPV) 4 blocker Ruthenium Red (RR) was injected in advance, and ventilated as in group A. In group D:TRPV4 blocker RR was injected ifrstly, and then ventilated as in group B. Atfer 12 h ventilation, we collected bronchoalveolar lavage lfuid (BALF), tested MUC (2, 5AC, 5B) protein content by ELISA, and detected the transcription of MUC (2, 5AC, 5B) mRNA of bronchial lung tissue by RT-PCR . Results:Compared with the normal ventilation (A2) group, the protein level of MUC of excessive ventilation (B2) group was significantly higher, mainly MUC5AC (P<0.05);compared with the normal ventilation (A1) group, the protein level of MUC of no ventilation (B1) group was signiifcantly decreased (P<0.05). Atfer pretreatment with RR, the MUC protein level of group C1, C2 were signiifcantly lower than that of group A1, A2 (P<0.05);the MUC protein level of group B2were significantly lower than that of group D2 (P<0.05). The MUC (2, 5AC and 5B) mRNA level was higher in excessive ventilation group (B2) than in normal ventilation group (A2). Atfer pretreatment with RR, in comparison with group A1, A2, the MUC (2, 5AC and 5B) mRNA level of group C1, C2 declined;in comparison with group B2, the MUC (2, 5AC and 5B) mRNA level of group D2 declined. Conclusion:Rhythmic pressure waves may regulate and balance basic airway mucin secretion through activating the TRPV4 channel in dogs.

  16. Role of the Earth's rotation in global geodynamics

    Science.gov (United States)

    Pavlenkova, N.

    2009-04-01

    degasification of the Earth (the fluids advection) and changes in the Earth rotation. At formation of the core there was the Earth's expansion and was formed system of global lineaments and the Pacific ring. Bipolar convection in the core has created a magnetic field and the increased advection of deep fluids in the southern hemisphere. The last promoted formation of thick continental lithosphere in this hemisphere in Archean-Proterozoi. This thick lithosphere has led to asymmetry of the planet and to relative displacement of the mass centers of the Earth's spheres. It produced high pressure between the spheres (Barkin, 2002) and could have initiated their relative displacements. As a uniform asthenosphere does not exist and the continents have deep roots such displacements were most probable on a surface of a liquid outer core. The marked mass centre dislocation has caused the turning of the mantle around the core with movement of the continental hemisphere from South Pole to the equator. It corresponds to the data on movement of paleomagnetic and paleoclimate poles that took place in Paleozoic era. The rotation of the mantle around the core passed non-uniformly: the tidal forces connected to periodic change of Earth's rotation axis position in system the Earth-Lund-Sun (Avsyuk, 1996) were imposed on the basic moving forces restoring the mass center balance. The periodic displacements of the mantle created conditions for alternation of tectonic activity epochs. Rotation of the mantle around the core created a new nonequilibrium system. Therefore in Mesozoic era a new stage begins: an expansion of the southern hemisphere which radius is now bigger, than the northern one. Such expansion created the regular system of the mid-oceanic ridges forming a ring around Antarctica with the symmetric Mid-Atlantic, Indian and Pacific ridges. Supposedly at the last stage the formation of the continent on South Pole (Antarctica) and destruction of a continental crust on the northern hemisphere

  17. Postural balance in low back pain patients

    DEFF Research Database (Denmark)

    Maribo, Thomas; Stengaard-Pedersen, Kristian; Jensen, Lone Donbæk

    2011-01-01

    Low back pain (LBP) patients have poorer postural control compared to healthy controls, and the importance of assessing and addressing balance is a matter of debate. In the clinic, balance is often tested by means of the one leg stand test (OLST) while research often employs center of pressure (Co...... Ratio) might be of clinical interest. This study aimed to assess postural balance in LBP patients by analyzing intra-session reliability of CoP parameters on a portable force platform, the Romberg Ratio, and the OLST. Furthermore, we aimed to determine whether CoP parameters and OLST measure identical...

  18. Sulfur Earth

    Science.gov (United States)

    de Jong, B. H.

    2007-12-01

    Variations in surface tension affect the buoyancy of objects floating in a liquid. Thus an object floating in water will sink deeper in the presence of dishwater fluid. This is a very minor but measurable effect. It causes for instance ducks to drown in aqueous solutions with added surfactant. The surface tension of liquid iron is very strongly affected by the presence of sulfur which acts as a surfactant in this system varying between 1.9 and 0.4 N/m at 10 mass percent Sulfur (Lee & Morita (2002), This last value is inferred to be the maximum value for Sulfur inferred to be present in the liquid outer core. Venting of Sulfur from the liquid core manifests itself on the Earth surface by the 105 to 106 ton of sulfur vented into the atmosphere annually (Wedepohl, 1984). Inspection of surface Sulfur emission indicates that venting is non-homogeneously distributed over the Earth's surface. The implication of such large variation in surface tension in the liquid outer core are that at locally low Sulfur concentration, the liquid outer core does not wet the predominantly MgSiO3 matrix with which it is in contact. However at a local high in Sulfur, the liquid outer core wets this matrix which in the fluid state has a surface tension of 0.4 N/m (Bansal & Doremus, 1986), couples with it, and causes it to sink. This differential and diapiric movement is transmitted through the essentially brittle mantle (1024 Pa.s, Lambeck & Johnson, 1998; the maximum value for ice being about 1030 Pa.s at 0 K, in all likely hood representing an upper bound of viscosity for all materials) and manifests itself on the surface by the roughly 20 km differentiation, about 0.1 % of the total mantle thickness, between topographical heights and lows with concomitant lateral movement in the crust and upper mantle resulting in thin skin tectonics. The brittle nature of the medium though which this movement is transmitted suggests that the extremes in topography of the D" layer are similar in range to

  19. Estudo da sinterização da zircônia dopada com óxidos de terras raras a 5 GPa de pressão Sintering of rare earth-doped zirconia under 5 GPa pressure

    Directory of Open Access Journals (Sweden)

    C. Kuranaga

    2005-06-01

    Full Text Available A zircônia (ZrO2 tem mostrado grande destaque entre as cerâmicas avançadas, atraindo muito o interesse de pesquisadores em seus vários campos de atuação. A zircônia apresenta elevada resistência quando na fase tetragonal, mas a fase estável a temperatura ambiente é a monoclínica, sendo necessário o uso de estabilizantes para a fase tetragonal. Neste trabalho propomos a sinterização rápida da zircônia parcialmente estabilizada com óxidos de terras raras (ZrO2-OTR, mediante o emprego da alta pressão de 5 GPa. As condições de sinterização realizadas neste trabalho são inovadoras, haja visto que utilizou-se de tecnologia alternativa para processar a ZrO2-OTR, chamada de altas temperaturas e altas pressões (HPHT. Foi utilizada uma pressão de 5 GPa, temperaturas de 1100, 1200 e 1300 ºC nos tempos de 2 e 5 min. O melhor resultado foi obtido nas amostras sinterizadas a 5 GPa/1300 ºC/5 min, onde apresentaram microdureza média de 488,73 kgf/mm², para uma tenacidade à fratura de 5,33 MPa.m½, as quais apresentaram densidade da ordem de 97,88% da teórica, e 88% em volume de fase tetragonal retida à temperatura ambiente.Zirconia (ZrO2 has shown great projection among the advanced ceramics, attracting the interest of researchers in its various fields of application. Tetragonal zirconia presents high mechanical strength, but the room temperature stable phase is the monoclinic, being necessary the use of stabilizers for obtaining the tetragonal phase. In this work the rapid sintering of zirconia partially stabilized with rare earth oxides (ZrO2-OTR, via 5 GPa high pressure is proposed. The sintering conditions employed in this work are innovative, due to the use of an alternative technology to process ZrO2-OTR, so called high temperature - high pressure (HPHT. A pressure of 5 GPa and temperatures of 1100, 1200 and 1300 ºC for times of 2 and 5 min were used. The best results were obtained for samples sintered at 5 GPa at 1300 º

  20. A preliminary study on pressure-plate evaluation of forelimb toe-heel and mediolateral hoof balance on a hard vs. a soft surface in sound ponies at the walk and trot

    NARCIS (Netherlands)

    Oosterlinck, M; Royaux, E; Back, W; Pille, F

    2014-01-01

    REASONS FOR PERFORMING STUDY: Thus far, pressure-plate analysis has been limited to measurements on a hard surface, whereas equine athletes routinely perform on a deformable substrate. OBJECTIVES: To explore pressure-plate analysis on arena footing. STUDY DESIGN: Nonrandomised crossover study using

  1. Balanced Scorecard voor inkoop

    NARCIS (Netherlands)

    Honing, van der R.; Schotanus, F.

    2003-01-01

    Een Balanced Scorecard kan ontwikkeld worden voor de hele organisatie, maar ook voor onderdelen daarvan. In dit artikel wordt ingegaan op de ontwikkeling van een Balanced Scorecard voor de inkoopafdeling

  2. Strength and Balance Exercises

    Science.gov (United States)

    ... Peripheral Artery Disease Venous Thromboembolism Aortic Aneurysm More Strength and Balance Exercises Updated:Sep 8,2016 If ... Be Safe While Being Active - Stretching & Flexibility Exercises - Strength & Balance Exercises - Problems & Solutions for Being Active - FAQs ...

  3. Conservative Pressures on Curriculum.

    Science.gov (United States)

    Bryson, Joseph E.

    Pressure on the public schools is coming from conservative New Right religious-political groups. Their concerns focus on: (1) secular humanism--a Godless form of religion that the public schools are alleged to be teaching; (2) scientific evolution versus creationism--the balanced treatment statute; (3) Bible clubs and prayer in the classroom; and…

  4. 临近地下室外墙影响下的考虑土拱效应的挡土墙主动土压力研究%Research on active earth pressure behind retaining wall adjacent to existing basements exterior wall considering soil arching effects

    Institute of Scientific and Technical Information of China (English)

    赵琦; 朱建明

    2014-01-01

    It was necessary to use the adaptive theory for computing the distribution of earth pressure behind the wall adjacent to existing basements and the height of total earth pressure, because it was inconsistent with the Rankine’s theory which was based on the semi-infinite half space state. It could be divided two parts of the deformation trends by considering soil arching effect. The upper soil parts slide down alongside the wall which is same with Terzaghi’s tarp door experiment. Also, the lower soil parts slide down as a triangle the soil wedge. So it is reliable that the earth pressure behind the retaining wall adjacent to existing basement should be analyzed based on the above deformation trends of the upper part and lower part. Assuming the arch in soil arching as circular, the lateral coefficients of earth pressure of retaining wall about both upper and lower parts are derived from the principal stress rotation. And the formula of distribution of lateral active earth pressure is given based on the soil static wedge equilibrium. Expressions of the total earth pressure and the height of acting point are derived by translation of coordinates. According to the examples, the results by proposed method are close to the simulation results. So it has a significant meaning for active earth pressure theory which considering the soil arching effect.%当挡土墙附近存在临近建筑地下室外墙时,其挡土墙土压力与传统的Rankine理论基于无限半空间体假定不符,因而在这种新的工程背景下需要采用合适的理论来计算挡土墙土压力及其作用点高度。已有的研究表明,这种条件下土体的变形趋势可分为上、下两大部分:上部土体变形类似于Terzaghi的活动门试验,土体沿着墙体下滑,而下部土体则沿着土楔形体而变形。因而将土拱效应用于求解挡土墙土压力的计算分成了上、下两大部分考虑。假定土拱形状为圆弧,基于主应力旋

  5. A metasomatic mechanism for the formation of Earth's earliest evolved crust

    Science.gov (United States)

    Baker, Don R.; Sofonio, Kassandra

    2017-04-01

    Following giant impacts the early Hadean Earth was shrouded in a steam atmosphere for durations on the order of 1 Ma. In order to investigate the potential of this atmosphere to fractionate major elements between various silicate reservoirs and influence a planet's geochemical evolution, we performed experiments simulating the interaction of a post-giant-impact steam atmosphere with a bulk silicate Earth (BSE) composition. Our experiments indicate that the composition of the solute in a water-rich atmosphere at 10 MPa and ∼727 °C is remarkably similar to that of Earth's modern continental crust and would constitute up to 10% of the solution mass. This solute composition is similar to solute compositions previously measured at higher pressures, but distinct from those of near-solidus peridotite melts. Mass balance calculations based upon the hypothesis that Earth's initial water concentration was similar to that in CI carbonaceous chondrites, and that degassing and metasomatism produced the BSE, indicate that metasomatism could produce from 10 to 300% of the mass of the modern crust. If instead the amount of metasomatism is estimated by the difference between the water concentration in the BSE and in the depleted upper mantle, then a mass of up to approximately 4% of the current crust could be produced by metasomatism. Using results of earlier research we find that the solute is expected to have a smaller Sm/Nd ratio than the residual BSE, and if the solute was formed early in Earth's history its Nd isotopic signatures would be highly enriched. Although we cannot be certain that the metasomatic process created a significant fraction of Earth's crust in the early Hadean, our research indicates that it has the potential to form crustal nuclei and possibly was responsible for the production of incompatible-element enriched reservoirs in the early Earth, as seen in the isotopic signatures of Archean rocks.

  6. Functional balance tests

    Directory of Open Access Journals (Sweden)

    Parvin Raji

    2012-12-01

    Full Text Available Background and Aim: All activities of daily living need to balance control in static and dynamic movements. In recent years, a numerous increase can be seen in the functional balance assessment tools. Functional balance tests emphasize on static and dynamic balance, balance in weight transfer, the equilibrium response to the imbalances, and functional mobility. These standardized and available tests assess performance and require minimal or no equipment and short time to run. Functional balance is prerequisite for the most static and dynamic activities in daily life and needs sufficient interaction between sensory and motor systems. According to the critical role of balance in everyday life, and wide application of functional balance tests in the diagnosis and assessment of patients, a review of the functional balance tests was performed.Methods: The Google Scholar, PubMed, Science Direct, Scopus, Magiran, Iran Medex, and IranDoc databases were reviewed and the reliable and valid tests which were mostly used by Iranian researchers were assessed.Conclusion: It seems that Berg balance scale (BBS have been studied by Iranian and foreign researches more than the other tests. This test has high reliability and validity in elderly and in the most neurological disorders.

  7. Planets under pressure

    Science.gov (United States)

    Jeanloz, Raymond

    2009-04-01

    Deep inside the planet Jupiter, diamonds hail down from hydrocarbon clouds as intense atmospheric pressures break methane into its atomic components. Further in - but still only 15% of the way to the planet's centre - the pressure reaches a million times that of the Earth's atmosphere. This is enough to transform hydrogen from the transparent, insulating gas we know at our planet's surface into a metallic fluid that sustains Jupiter's huge magnetic field. Even diamond is not forever: at pressures of 8-10 million atmospheres it is transformed into an opaque, metallic form of carbon, rather than the familiar transparent crystal.

  8. Medical Devices Assess, Treat Balance Disorders

    Science.gov (United States)

    2009-01-01

    You may have heard the phrase as difficult as walking and chewing gum as a joking way of referring to something that is not difficult at all. Just walking, however, is not all that simple physiologically speaking. Even standing upright is an undertaking requiring the complex cooperation of multiple motor and sensory systems including vision, the inner ear, somatosensation (sensation from the skin), and proprioception (the sense of the body s parts in relation to each other). The compromised performance of any of these elements can lead to a balance disorder, which in some form affects nearly half of Americans at least once in their lifetimes, from the elderly, to those with neurological or vestibular (inner ear) dysfunction, to athletes with musculoskeletal injuries, to astronauts returning from space. Readjusting to Earth s gravity has a significant impact on an astronaut s ability to balance, a result of the brain switching to a different "model" for interpreting sensory input in normal gravity versus weightlessness. While acclimating, astronauts can experience headaches, motion sickness, and problems with perception. To help ease the transition and study the effects of weightlessness on the body, NASA has conducted many investigations into post-flight balance control, realizing this research can help treat patients with balance disorders on Earth as well. In the 1960s, the NASA-sponsored Man Vehicle Laboratory at the Massachusetts Institute of Technology (MIT) studied the effects of prolonged space flight on astronauts. The lab s work intrigued MIT doctoral candidate Lewis Nashner, who began conducting NASA-funded research on human movement and balance under the supervision of Dr. Larry Young in the MIT Department of Aeronautics and Astronautics. In 1982, Nashner s work resulted in a noninvasive clinical technique for assessing the cooperative systems that allow the body to balance, commonly referred to as computerized dynamic posturography (CDP). CDP employs a

  9. Free oscillation of the Earth

    Directory of Open Access Journals (Sweden)

    Y. Abedini

    2000-06-01

    Full Text Available   This work is a study of the Earths free oscillations considering a merge of solid and liquid model. At the turn of 19th century Geophysicists presented the theory of the free oscillations for a self-gravitating, isotropic and compressible sphere. Assuming a steel structure for an Earth size sphere, they predicted a period of oscillation of about 1 hour. About 50 years later, the free oscillations of stars was studied by Cowling and others. They classified the oscillation modes of the stars into acoustic and gravity modes on the basis of their driving forces. These are pressure and buoyancy forces respectively. The earliest measurements for the period of the free oscillations of the Earth was made by Benyove from a study of Kamchathca earthquake. Since then, the Geophysicists have been trying to provide a theoretical basis for these measurements. Recently, the theory concerning oscillations of celestial fluids is extended by Sobouti to include the possible oscillations of the Earthlike bodies. Using the same technique, we study the free oscillations of a spherically symmetric, non-rotating and elastic model for the Earth.   We used the actual data of the Earths interior structure in our numerical calculations. Numerical results show that there exist three distinct oscillation modes namely acoustic, gravity and toroidal modes. These modes are driven by pressure, buoyancy and shear forces respectively. The shear force is due to the elastic properties of the solid part of the Earth. Our numerical results are consistent with the seismic data recorded from earthquake measurements.

  10. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ Oversupply of rare earths led to the significant price drop of rare earth mineral products and separated products in Chinese domestic market. To stabilize the price, prevent waste of resources, further improve regulation capability on domestic rare earth market and rare earth price and maintain sustaining and healthy development of rare earth industry, partial rare earth producers in Baotou and Jiangxi province projected to cease the production for one month.

  11. Regimes of validity for balanced models

    Science.gov (United States)

    Gent, Peter R.; McWilliams, James C.

    1983-07-01

    Scaling analyses are presented which delineate the atmospheric and oceanic regimes of validity for the family of balanced models described in Gent and McWilliams (1983a). The analyses follow and extend the classical work of Charney (1948) and others. The analyses use three non-dimensional parameters which represent the flow scale relative to the Earth's radius, the dominance of turbulent or wave-like processes, and the dominant component of the potential vorticity. For each regime, the models that are accurate both at leading order and through at least one higher order of accuracy in the appropriate small parameter are then identified. In particular, it is found that members of the balanced family are the appropriate models of higher-order accuracy over a broad range of parameter regimes. Examples are also given of particular atmospheric and oceanic phenomena which are in the regimes of validity for the different balanced models.

  12. Procedure for Balancing an Air Distribution System with Decentralised Fans

    DEFF Research Database (Denmark)

    Gunner, Amalie; Hultmark, Göran; Vorre, Anders;

    2015-01-01

    This paper presents results from an on-going project concerning new design procedures for mechanical ventilation systems with low energy use. Conventional constant air volume (CAV) systems are usually balanced using flat plate dampers. The purpose of using balancing dampers is to intentionally...... flawed. This paper presents a new procedure for balancing of CAV systems in combination with decentralised fans. The new system was based on replacing the balancing dampers with decentralised fans. By replacing the balancing dampers with decentralised fans, airflows can be balanced by adjusting the speed...... of the fans. In conventional air distribution systems the fan provides the necessary pressure to overcome the resistance in the branch with the highest pressure resistance. This gives an unnecessary overpressure in the remaining branches that does not provide any useful purpose. In order to decrease the fan...

  13. A safety analysis of warhead balancing

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.

    1998-12-01

    Reentry vehicles (RVs) carrying warheads from ballistic missiles must be carefully balanced with the warhead in situ to prevent wobble as the RVs enter the earth`s atmosphere to prevent inaccuracy or loss of the warhead. This balancing is performed on a dynamic balancing machine that rotates the RV at significant angular velocities. Seizure of the spindle shaft of the machine could result in rapid deceleration of the rotating assembly, which could over-stress and shear bolts or other structures that attach the RV to the balancing machine. This could result in undesired motions of the RV and impact of the RV on equipment or structures in the work area. This potential safety problem has long been recognized in a general way, but no systematic investigation of the possible accident sequences had been performed. The purpose of this paper is to describe an integrated set of systems analysis techniques that worked well in developing a set of accident sequences that describe the motions of the RV following a spindle-shaft seizure event.

  14. Low-Hysteresis Flow-Through Wind-Tunnel Balance

    Science.gov (United States)

    Kunz, N.; Luna, P. M.; Roberts, A. C.; Smith, R. C.; Horne, W. L.; Smith, K. M.

    1992-01-01

    Improved flow-through wind-tunnel balance includes features minimizing both spurious force readings caused by internal pressurized flow and mechanical hysteresis. Symmetrical forces caused by internal flow cancelled.

  15. Identifying Balance in a Balanced Scorecard System

    Science.gov (United States)

    Aravamudhan, Suhanya; Kamalanabhan, T. J.

    2007-01-01

    In recent years, strategic management concepts seem to be gaining greater attention from the academicians and the practitioner's alike. Balanced Scorecard (BSC) concept is one such management concepts that has spread in worldwide business and consulting communities. The BSC translates mission and vision statements into a comprehensive set of…

  16. 砂土中刚性挡墙不同主动变位模式任意位移土压力计算%EARTH PRESSURES ON RIGID RETAINING WALLS IN SANDY SOIL WITH DIFFERENT ACTIVE MOVEMENT MODES UNDER ARBITRARRY DEFORMATION

    Institute of Scientific and Technical Information of China (English)

    应宏伟; 郑贝贝

    2012-01-01

    已有模型实验及现场实测表明,刚性挡墙随着变位模式和位移量的变化,主动土压力合力和分布均发生改变,有时甚至与经典理论的线性分布有很大不同。采用中间状态系数定义非极限状态,提出了砂土中刚性挡墙不同主动位移模式下非极限状态土压力合力系数的计算公式;将墙后士体简化为连续非线性弹簧和刚塑性体的组合体作用在挡墙上,得到了不同位移模式任意位移的土压力分布和合力作用点高度。与已有理论方法和实验结果对比表明,该文方法在三种典型位移模式下与实验数据吻合更好。研究还发现,平动模式土压力呈线性分布,其合力随挡墙位移量的增大易趋于稳定并到达极限状态;绕墙底和绕墙顶转动模式下土压力合力随着位移增大只能接近极限状态且呈非线性分布。绕底转动时,土压力分布曲线逐渐向上凹,合力作用点高度趋于降低;绕顶转动时,分布曲线则逐渐向上凸,合力作用点高度趋于升高,墙顶附近表现出明显的土拱效应。%Previous experimental and monitored results on earth pressures had shown that the resultant and distribution of active earth pressures on rigid retaining wails varied with modes and magnitudes of wall movement. The distribution of earth pressures sometimes differed obviously from a linear distribution according to classical earth pressure theories. A middle-state coefficient was adopted to define the non-limit state, and the formulae of the coefficients of the resultant earth pressures on rigid retaining walls in sandy backfills at a non-limit state with different deformations were proposed. The soil behind the wall was simplified as the combination of nonlinear springs and a rigid plasticity object which applied on the wall, and the unit active pressure and the heights of points of application of pressures were obtained. The comparisons among the

  17. Conclusion: The balanced company

    DEFF Research Database (Denmark)

    Scheuer, John Damm; Jensen, Inger

    2013-01-01

    This concluding chapter brings together the various research findings of the book "The balanced company - organizing for the 21st Century" and develops a general overview of their implications for our understanding of the balancing processes unfolding in companies and organizations....

  18. Keeping Your Balance

    Science.gov (United States)

    ... News & Events Press Releases NOF in the News Osteoporosis in the News Press/Media Kit NOF Events Blog Advocacy NOF Store Shopping Cart Home › Patients › Fractures/Fall Prevention › Exercise/Safe Movement › Keeping Your Balance Keeping Your Balance ...

  19. Leadership: A Balancing Act

    Science.gov (United States)

    Hines, Thomas E.

    2011-01-01

    Maintaining balance in leadership can be difficult because balance is affected by the personality, strengths, and attitudes of the leader as well as the complicated environment within and outside the community college itself. This article explores what being a leader at the community college means, what the threats are to effective leadership, and…

  20. Balancing Trust and Control

    DEFF Research Database (Denmark)

    Jagd, Søren

    This paper focuses on the leadership challenge of balancing trust and control. The relation between trust and control has for a long time been a puzzling issue for management researchers. In the paper I first show that there has been a dramatic change in the way the relation between trust...... and control has been conceptualized in trust research. While the relation between trust and control earlier was conceptualized as a more or less stable balance between trust and control, more recent research conceptualizes the relation between trust and control more as a dynamical process that involves...... an ongoing process of balancing the relation between trust and control. Second, taking the departure in the recent conceptualization of the balance between trust and control as an interactive process I discuss the challenges for management in handling this more subtle balancing of trust and control...

  1. Volatile accretion history of the Earth.

    Science.gov (United States)

    Wood, B J; Halliday, A N; Rehkämper, M

    2010-10-28

    It has long been thought that the Earth had a protracted and complex history of volatile accretion and loss. Albarède paints a different picture, proposing that the Earth first formed as a dry planet which, like the Moon, was devoid of volatile constituents. He suggests that the Earth's complement of volatile elements was only established later, by the addition of a small veneer of volatile-rich material at ∼100 Myr (here and elsewhere, ages are relative to the origin of the Solar System). Here we argue that the Earth's mass balance of moderately volatile elements is inconsistent with Albarède's hypothesis but is well explained by the standard model of accretion from partially volatile-depleted material, accompanied by core formation.

  2. Pipe Construction of Balance of 1 000 MW Pressurized Water Reactor Nuclear Power Plant%1000MW压水堆核电站辅助设施管道施工

    Institute of Scientific and Technical Information of China (English)

    廖建华

    2011-01-01

    主要探讨了核电站辅助设施(balance of the plant,BOP)管道施工中出现的一些技术问题,如施工质量的可追溯性、共用支架防变形、电抛光管内部的洁净控制、沟槽式管件的应用等,并结合实际制订了相应的技术措施.这些措施通过现场的实际操作检验,证实了简单、有效,为后续核电BOP管道施工提供了借鉴.

  3. Earth from Above

    Science.gov (United States)

    Stahley, Tom

    2006-01-01

    Google Earth is a free online software that provides a virtual view of Earth. Using Google Earth, students can view Earth by hovering over features and locations they preselect or by serendipitously exploring locations that catch their fascination. Going beyond hovering, they can swoop forward and even tilt images to make more detailed…

  4. High-pressure neutron diffraction

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory

    2011-01-10

    This lecture will cover progress and prospect of applications of high-pressure neutron diffraction techniques to Earth and materials sciences. I will first introduce general high-pressure research topics and available in-situ high-pressure techniques. Then I'll talk about high-pressure neutron diffraction techniques using two types of pressure cells: fluid-driven and anvil-type cells. Lastly, I will give several case studies using these techniques, particularly, those on hydrogen-bearing materials and magnetic transitions.

  5. Rare Earth Resolution

    Institute of Scientific and Technical Information of China (English)

    Mei Xinyu

    2012-01-01

    BEFORE the early 1970s, China had no rare earth exports, and the world rare earth market was dominated by the United States, Europe and Japan. In the 1970s, China began to enter the world rare earth market and its share has picked up sharply in the following decades. Today, having the monopoly over global rare earth production, China must improve the benefits from rare earth production, not only from producing individual rare earth products, but also from mastering the intensive processing of rare earth products.

  6. 考虑渗流影响的基坑土钉支护整体稳定性分析中水压力的估算%Appraisal of Water Pressure in Stability Analysis of Earth Nail Bracing For Foundation Pit Considering the Effect of Seepage

    Institute of Scientific and Technical Information of China (English)

    郭红仙; 程晓辉; 李静

    2001-01-01

    本文重点介绍在典型工程水文地质条件下,基坑土钉支护整体稳定性分析中,所涉及的水压 力的计算机辅助流网法估算,并进行了算例分析。%Appraisal of water pressure in the stability analysis of earth nail bracing for foundation pit under typical hydrogeologic condition by method of computer-aided flow net is introduced herein. A case history is also given.

  7. Application of Pascal Principle in Earth Science

    Science.gov (United States)

    Samimi Namin, M.

    2009-12-01

    The Pascal experiment is interpreted and the chamber is roughly defined. Pascal experiment in relation to Pascal principle compared with a chamber in the earth crust. It is conclude that: 1: The pressure (P) inside the Pascal's cylinder is the combination of two pressure; the external pressure (P1) and the hydraulic pressure (P2). Pc=P1+P2 The direction of the force is from top to bottom. In the case of the chamber the pressure is Pch=P1-P2 and its positive direction is regarded to be from bottom to top. P1 is the external pressure, and is the maximum pressure applied to chamber .The external pressure creates a constant internal pressure throughout the chamber .The magnitude of the constant pressure is based on the litho static pressure of the bottom of the chamber; because it is the maximum pressure that the chamber is connected. P1=ρ1gH+ρ2gh Where H is the overburden thickness, h is the highness of the chamber, ρ1 is the density of the overburden and ρ2 is density of country rock. The hydrostatic pressure within the chamber is P2=ρ3gh. Also ρ3 is the density of the chamber. So the pressure inside the chamber would be: Pch=P1-P2 then Pch=ρ1gH+(ρ2-ρ3)gh. The equation above means that, the chamber pressure equals to the overburden pressure plus Archimedes pressure. 2: The word squeezing which is a vulgar word has an important physical meaning that is ((Pascal principle driving movement)).In another word, almost all movements, related to chambers, within the earth are a squeezing event which's, driving force is the steady constant pressure mentioned above. Any change in this pressure depends on the rupturing of the chamber and the behavior of the movement of the chamber matter. 3: If we provide a safety valve on piston of the Pascal's cylinder and increase the load we see the safety valve bursts and the matter inside the cylinder squeeze out .The pressure is from top to bottom but the movement is from bottom to top. The direction of force has changed 180

  8. EarthLabs - Investigating Hurricanes: Earth's Meteorological Monsters

    Science.gov (United States)

    McDaris, J. R.; Dahlman, L.; Barstow, D.

    2007-12-01

    which students investigate the different interactions involved in hurricane generation, steering, and intensification. Students analyze a variety of visualization resources looking for patterns in occurrence and to develop an understanding of hurricane structure. They download archived data about past hurricanes and produce temporal and spatial plots to discover patterns in hurricane life cycles. They investigate the relationship between hurricane wind speed and factors such as barometric pressure and sea surface temperature by conducting spreadsheet analyses on archived data. They also conduct hands-on laboratory experiments in order to understand the physical processes that underpin energy transfer in convection, condensation, and latent heat. These activities highlight Earth science as a vital, rich, invigorating course, employing state-of-the-art technologies and in-depth labs with high relevance for our daily lives and the future.

  9. Significance of Plantar Pressure Balance and Gait Stability in Early Prevention and Cure of Diabetic Foot%平衡足底压力及稳定步态在早期糖尿病足防治中的意义

    Institute of Scientific and Technical Information of China (English)

    胡伊玢; 孟晓静

    2013-01-01

    patients ( Wanger classification = 0 ) were divided randomly into groups therapy and control, 21 in each. Belgian - footscan(R) plantar pressure gait detection system was used to monitor dynamical plantar pressure and static impulse in 2 groups, and then made personalized programs to balance plantar pressure based on the monitoring data in therapy group. Control group received conventional treatment without personalized programs. Two groups were followed up for 1 year, to observe the plantar pressure, gait stability curve, incidence of foot ulcers, impulse before and after treatment. Results No significant difference in plantar pressure between 2 groups before treatment ( P > 0. 05 ). After 1 year of treatment, the pretreatment pressures of the 3rd, 4th, 5th metatarsal base of control group were higher than those in control group before treatment and those in therapy group after treatment, the differences were significant ( P 0. 05 ). After treatment, the gait balance curve fluctuated remarkably and gravity pressure distribution curve was a little short of smoothness ( namely gait stability was not good ) in control group, while in therapy group no obvious fluctuation was noted, the plantar pressure distribution was balanced. The incidences of foot ulcers were 42. 9% ( 9/21 ) in control group, 14. 3% ( 3/ 21 ) in therapy group, the difference was significant ( P 65% [ 42. 9% ( 9/21 ) vs. 14. 3% ( 3/21 ) ] between control group and therapy group ( P > 0. 05 ). Conclusion Plantar pressure change is one of the important causes of diabetic foot ulcers. Early detection and evaluation of plantar pressure of diabetic patients is very important, and positive and effective measures to balance plantar pressure can reduce incidence of foot ulcers, to decrease amputation rate from source to guarantee the quality of life of diabetes patients.

  10. Field Aligned Currents Derived from Pressure Profiles Obtained from TWINS ENA Images

    Science.gov (United States)

    Wood, K.; Perez, J. D.; McComas, D. J.; Goldstein, J.; Valek, P. W.

    2015-12-01

    Field aligned currents (FACs) that flow from the Earth's magnetosphere into the ionosphere are an important coupling mechanism in the interaction of the solar wind with the Earth's magnetosphere. Assuming pressure balance along with charge conservation yields an expression for the FACs in terms of plasma pressure gradients and pressure anisotropy. The Two Wide-Angle Imaging Neutral Atom Spectrometers (TWINS) mission, the first stereoscopic ENA magnetospheric imager, provides global images of the inner magnetosphere from which ion pressure distributions and pressure anisotropies can be obtained. Following the formulations in Heineman [1990] and using results from TWINS observations, we calculate the distribution of field aligned currents for the 17-18 March 2015 geomagnetic storm in which extended ionospheric precipitation was observed. Initial results for the field aligned currents will be generated assuming an isotropic pitch angle distribution. Global maps of field aligned currents during the main and recovery phase of the storm will be presented. Heinemann, H. (1990), Representations of Currents and Magnetic Fields in Anisotropic Magnetohydrostatic Plasma, J. Geophys. Res., 95, 7789.

  11. Load Balancing Scientific Applications

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, Olga Tkachyshyn [Texas A & M Univ., College Station, TX (United States)

    2014-12-01

    The largest supercomputers have millions of independent processors, and concurrency levels are rapidly increasing. For ideal efficiency, developers of the simulations that run on these machines must ensure that computational work is evenly balanced among processors. Assigning work evenly is challenging because many large modern parallel codes simulate behavior of physical systems that evolve over time, and their workloads change over time. Furthermore, the cost of imbalanced load increases with scale because most large-scale scientific simulations today use a Single Program Multiple Data (SPMD) parallel programming model, and an increasing number of processors will wait for the slowest one at the synchronization points. To address load imbalance, many large-scale parallel applications use dynamic load balance algorithms to redistribute work evenly. The research objective of this dissertation is to develop methods to decide when and how to load balance the application, and to balance it effectively and affordably. We measure and evaluate the computational load of the application, and develop strategies to decide when and how to correct the imbalance. Depending on the simulation, a fast, local load balance algorithm may be suitable, or a more sophisticated and expensive algorithm may be required. We developed a model for comparison of load balance algorithms for a specific state of the simulation that enables the selection of a balancing algorithm that will minimize overall runtime.

  12. Consideration of Dynamical Balances

    Science.gov (United States)

    Errico, Ronald M.

    2015-01-01

    The quasi-balance of extra-tropical tropospheric dynamics is a fundamental aspect of nature. If an atmospheric analysis does not reflect such balance sufficiently well, the subsequent forecast will exhibit unrealistic behavior associated with spurious fast-propagating gravity waves. Even if these eventually damp, they can create poor background fields for a subsequent analysis or interact with moist physics to create spurious precipitation. The nature of this problem will be described along with the reasons for atmospheric balance and techniques for mitigating imbalances. Attention will be focused on fundamental issues rather than on recipes for various techniques.

  13. A Unit Maintenance Scheduling Model Considering Peak Regulation Pressure Balance for Power System Containing Wind Farms%含风电场的电力系统中考虑调峰压力平衡的机组检修规划模型

    Institute of Scientific and Technical Information of China (English)

    吴耀武; 邴焕帅; 娄素华

    2012-01-01

    Grid-connection of large-scale wind power system brings new challenge to peak regulation of power grid and the maintenance outage of wind power generators has a certain effect on peak regulation ability of power grid. Along with the increase of the scale of grid-connected wind farm the coordination of power grid peak regulation ability should be considered in unit maintenance scheduling. A medium- and long-term unit maintenance scheduling, in which the economy of maintenance, reliability and balance of peak regulation pressure is synthetically taken into account, is proposed for power grid containing wind farms. Combining with the influence of grid-connected wind farms on peak regulation of power grid and peak regulation ability of different types of units, an index to measure peak regulation pressure for power grid containing wind power systems is proposed. On this basis, a method to balance the peak regulation pressure in maintenance scheduling is researched. According to different peak regulation abilities of units and the intensity of peak regulation pressure in different time intervals the unit maintenance is reasonably scheduled to balance peak regulation pressure of power grid; the constraint of maximum peak regulation of power grid is added in constraint conditions to ensure that after the maintenance scheduling is drafted the peak regulation pressure of power grid can be kept to a reasonable level. The proposed model is solved by genetic algorithm. The availability of the proposed model is verified by results of calculation example.%大规模风电并网给电力系统的调峰带来新的挑战,发电机组检修停运将对系统的调峰能力产生一定的影响,随着并网风电规模地加大,机组检修规划需要考虑系统的调峰能力协调问题.在含风电场的电力系统中,提出了综合考虑检修经济性、可靠性和调峰压力平衡的中长期机组检修规划模型.结合风电接入后对系统调峰的影响及不同

  14. Martian Atmospheric Pressure Static Charge Elimination Tool

    Science.gov (United States)

    Johansen, Michael R.

    2014-01-01

    A Martian pressure static charge elimination tool is currently in development in the Electrostatics and Surface Physics Laboratory (ESPL) at NASA's Kennedy Space Center. In standard Earth atmosphere conditions, static charge can be neutralized from an insulating surface using air ionizers. These air ionizers generate ions through corona breakdown. The Martian atmosphere is 7 Torr of mostly carbon dioxide, which makes it inherently difficult to use similar methods as those used for standard atmosphere static elimination tools. An initial prototype has been developed to show feasibility of static charge elimination at low pressure, using corona discharge. A needle point and thin wire loop are used as the corona generating electrodes. A photo of the test apparatus is shown below. Positive and negative high voltage pulses are sent to the needle point. This creates positive and negative ions that can be used for static charge neutralization. In a preliminary test, a floating metal plate was charged to approximately 600 volts under Martian atmospheric conditions. The static elimination tool was enabled and the voltage on the metal plate dropped rapidly to -100 volts. This test data is displayed below. Optimization is necessary to improve the electrostatic balance of the static elimination tool.

  15. The Effects of Virtual Reality-based Balance Training on Balance of the Elderly.

    Science.gov (United States)

    Cho, Gyeong Hee; Hwangbo, Gak; Shin, Hyung Soo

    2014-04-01

    [Purpose] The objective of this study was to determine the effects of virtual reality-based balance training on balance of the elderly. [Methods] The subjects were 32 healthy elderly people aged between 65 and 80, who were divided into a VR (virtual reality) training group (n=17) and a control group (n=15). The VR training group engaged in a 30-minute exercise session using Wii Fit three times a week for eight weeks, while the control group received no intervention. The balance of the two groups was measured before and after the intervention. [Results] According to the Romberg Test conducted to examine the effects of the training on balance, both the area covered by the body's center of pressure movement, and movement distances per unit area of the body's center of pressure envelope significantly decreased in the VR training group. Moreover, the two groups showed significant differences in balance. [Conclusion] Virtual reality training is effective at improving the balance of the healthy elderly. Thus, virtual reality training can be proposed as a form of fall prevention exercise for the elderly.

  16. THE SIGNAL APPROACH TO MODELLING THE BALANCE OF PAYMENT CRISIS

    Directory of Open Access Journals (Sweden)

    O. Chernyak

    2016-12-01

    Full Text Available The paper considers and presents synthesis of theoretical models of balance of payment crisis and investigates the most effective ways to model the crisis in Ukraine. For mathematical formalization of balance of payment crisis, comparative analysis of the effectiveness of different calculation methods of Exchange Market Pressure Index was performed. A set of indicators that signal the growing likelihood of balance of payments crisis was defined using signal approach. With the help of minimization function thresholds indicators were selected, the crossing of which signalize increase in the probability of balance of payment crisis.

  17. The Balanced Company

    DEFF Research Database (Denmark)

    is to be achieved and what should be avoided? • Through what types of processes are the criteria, conditions and values that are to be realised or taken into consideration constructed and decided upon? • What characterises the content, differences and complexity of the different types of values and criteria...... that a company is respected in wider society and behaves according to ethical standards. Strategists and Leaders need to make balanced choices about long-term goals and the allocation of resources. They need to analyse, understand and adjust strategies to market, political, value and technology related changes...... in their environments. Communication specialists need to make balanced decisions which take the different value systems and assumptions of stakeholders into consideration. Change specialists need to balance the need for continuity and change. Managers need to make balanced decisions about whether to achieve goals...

  18. Energy balance measurement

    DEFF Research Database (Denmark)

    Dhurandhar, N V; Schoeller, D; Brown, A W;

    2014-01-01

    Energy intake (EI) and physical activity energy expenditure (PAEE) are key modifiable determinants of energy balance, traditionally assessed by self-report despite its repeated demonstration of considerable inaccuracies. We argue here that it is time to move from the common view that self-reports...... of energy balance.International Journal of Obesity advance online publication, 23 December 2014; doi:10.1038/ijo.2014.199.......Energy intake (EI) and physical activity energy expenditure (PAEE) are key modifiable determinants of energy balance, traditionally assessed by self-report despite its repeated demonstration of considerable inaccuracies. We argue here that it is time to move from the common view that self......-reports of EI and PAEE are imperfect, but nevertheless deserving of use, to a view commensurate with the evidence that self-reports of EI and PAEE are so poor that they are wholly unacceptable for scientific research on EI and PAEE. While new strategies for objectively determining energy balance...

  19. 足底压力式步态分析中痉挛型脑瘫儿童的平衡能力特征%Balancing characteristics of children with spastic cerebral palsy during gait measurement using plantar pressure gait analysis system

    Institute of Scientific and Technical Information of China (English)

    李海; 周安艳

    2009-01-01

    目的:临床上坐位、站立位的平衡测试常利用平衡仪来进行,但由于平衡仪足踏板的限制,无法对脑性瘫痪(脑瘫)患儿步行时动态连续步行周期的平衡能力进行测试.文章利用足底压力式步态分析技术,观察痉挛型脑瘫儿童步行时在平衡能力方面的特征.方法:选择具有正常步行能力的健康儿毫78例作为正常儿童组,另外选择2004 05/2007-05在深圳市儿童医院康复科日间病房住院治疗的脑瘫患儿25例作为脑瘫儿童组.利用足底压力式步态分析系统,对2组对象分别进行足底压力式步态分析,记录2组儿童步行时的足底压力数据.观测指标分为量化指标和直观压力图.量化指标包括步频、步态周期时间、步态周期各时相的绝对对称性指标等参数.直观压力图包括动态足底压力图以及足底压力重心偏移轨迹图.结果:与正常儿童组相比,脑瘫儿童组步频较小,步态周期时间较长(P<0.01).脑瘫儿童组单足支撑期、摆动期、双足支撑期、步态周期时间的绝对对称性指标均大于正常儿童组(P<0.05).脑瘫儿童步行时双足的足底压力图的对称性、重复性较正常儿童差;重心偏移轨迹图不能形成左右对称的蝴蝶状图形.结论:痉挛型脑瘫儿童步行时,步态周期各时相均存在对称性下降的情况.足底压力式步态分析技术能有效地应用于痉挛型脑瘫儿童步态的平衡能力评估.%OBJECTIVE: Usually, the balance tests of sitting and standing position are performed by balancing instruments clinicalty, but because of the restriction of foot pedal, this kind of instruments cannot measure balancing ability in continuous dynamic gait cycles in gait of cerebral palsy children. Using plantar pressure gait analysis system, this study sought to study balance characteristics in gait of children with spastic cerebral palsy.METHODS: A total of 78 healthy children served as normal control group, and

  20. Balance Function Disorders

    Science.gov (United States)

    1991-01-01

    Researchers at the Balance Function Laboratory and Clinic at the Minneapolis (MN) Neuroscience Institute on the Abbot Northwestern Hospital Campus are using a rotational chair (technically a "sinusoidal harmonic acceleration system") originally developed by NASA to investigate vestibular (inner ear) function in weightlessness to diagnose and treat patients with balance function disorders. Manufactured by ICS Medical Corporation, Schaumberg, IL, the chair system turns a patient and monitors his or her responses to rotational stimulation.

  1. 2013 social balance sheet

    OpenAIRE

    Pierrette Heuse

    2014-01-01

    The transposition into national law of Directive 2013/34/EU on the annual financial statements of companies, expected by no later than July 2015, could alter the statistical obligations on small firms in connection with the filing of their annual accounts. In any case, the social balance sheet can no longer form an integral part of their accounts. Nevertheless, it contains original information whose usefulness is highlighted, on the basis of the social balance sheets for 2012, by examining th...

  2. The Lifeworld Earth and a Modelled Earth

    Science.gov (United States)

    Juuti, Kalle

    2014-01-01

    The goal of this paper is to study the question of whether a phenomenological view of the Earth could be empirically endorsed. The phenomenological way of thinking considers the Earth as a material entity, but not as an object as viewed in science. In the learning science tradition, tracking the process of the conceptual change of the shape of the…

  3. Balances instruments, manufacturers, history

    CERN Document Server

    Robens, Erich; Kiefer, Susanne

    2014-01-01

    The book deals mainly with direct mass determination by means of a conventional balances. It covers the history of the balance from the beginnings in Egypt earlier than 3000 BC to recent developments. All balance types are described with emphasis on scientific balances. Methods of indirect mass determination, which are applied to very light objects like molecules and the basic particles of matter and celestial bodies, are included.  As additional guidance, today’s manufacturers are listed and the profile of important companies is reviewed. Several hundred photographs, reproductions and drawings show instruments and their uses. This book includes commercial weighing instruments for merchandise and raw materials in workshops as well as symbolic weighing in the ancient Egyptian’s ceremony of ‘Weighing of the Heart’, the Greek fate balance, the Roman  Justitia, Juno Moneta and Middle Ages scenes of the Last Judgement with Jesus or St. Michael and of modern balances. The photographs are selected from the...

  4. Thermodynamics of the Earth

    Energy Technology Data Exchange (ETDEWEB)

    Stacey, Frank D [CSIRO Exploration and Mining, PO Box 883, Kenmore, Qld. 4069 (Australia)], E-mail: Frank.Stacey@csiro.au

    2010-04-15

    Applications of elementary thermodynamic principles to the dynamics of the Earth lead to robust, quantitative conclusions about the tectonic effects that arise from convection. The grand pattern of motion conveys deep heat to the surface, generating mechanical energy with a thermodynamic efficiency corresponding to that of a Carnot engine operating over the adiabatic temperature gradient between the heat source and sink. Referred to the total heat flux derived from the Earth's silicate mantle, the efficiency is 24% and the power generated, 7.7 x 10{sup 12} W, causes all the material deformation apparent as plate tectonics and the consequent geological processes. About 3.5% of this is released in seismic zones but little more than 0.2% as seismic waves. Even major earthquakes are only localized hiccups in this motion. Complications that arise from mineral phase transitions can be used to illuminate details of the motion. There are two superimposed patterns of convection, plate subduction and deep mantle plumes, driven by sources of buoyancy, negative and positive respectively, at the top and bottom of the mantle. The patterns of motion are controlled by the viscosity contrasts (>10{sup 4} : 1) at these boundaries and are self-selected as the least dissipative mechanisms of heat transfer for convection in a body with very strong viscosity variation. Both are subjects of the thermodynamic efficiency argument. Convection also drives the motion in the fluid outer core that generates the geomagnetic field, although in that case there is an important energy contribution by compositional separation, as light solute is rejected by the solidifying inner core and mixed into the outer core, a process referred to as compositional convection. Uncertainty persists over the core energy balance because thermal conduction is a drain on core energy that has been a subject of diverse estimates, with attendant debate over the need for radiogenic heat in the core. The geophysical

  5. Pressure Dome for High-Pressure Electrolyzer

    Science.gov (United States)

    Norman, Timothy; Schmitt, Edwin

    2012-01-01

    A high-strength, low-weight pressure vessel dome was designed specifically to house a high-pressure [2,000 psi (approx. = 13.8 MPa)] electrolyzer. In operation, the dome is filled with an inert gas pressurized to roughly 100 psi (approx. = 690 kPa) above the high, balanced pressure product oxygen and hydrogen gas streams. The inert gas acts to reduce the clamping load on electrolyzer stack tie bolts since the dome pressure acting axially inward helps offset the outward axial forces from the stack gas pressure. Likewise, radial and circumferential stresses on electrolyzer frames are minimized. Because the dome is operated at a higher pressure than the electrolyzer product gas, any external electrolyzer leak prevents oxygen or hydrogen from leaking into the dome. Instead the affected stack gas stream pressure rises detectably, thereby enabling a system shutdown. All electrical and fluid connections to the stack are made inside the pressure dome and require special plumbing and electrical dome interfaces for this to be accomplished. Further benefits of the dome are that it can act as a containment shield in the unlikely event of a catastrophic failure. Studies indicate that, for a given active area (and hence, cell ID), frame outside diameter must become ever larger to support stresses at higher operating pressures. This can lead to a large footprint and increased costs associated with thicker and/or larger diameter end-plates, tie-rods, and the frames themselves. One solution is to employ rings that fit snugly around the frame. This complicates stack assembly and is sometimes difficult to achieve in practice, as its success is strongly dependent on frame and ring tolerances, gas pressure, and operating temperature. A pressure dome permits an otherwise low-pressure stack to operate at higher pressures without growing the electrolyzer hardware. The pressure dome consists of two machined segments. An O-ring is placed in an O-ring groove in the flange of the bottom

  6. Analyzing Hydrological Sustainability Through Water Balance

    Science.gov (United States)

    Menció, Anna; Folch, Albert; Mas-Pla, Josep

    2010-05-01

    The objective of the Water Framework Directive (2000/60/EC) is to assist in the development of management plans that will lead to the sustainable use of water resources in all EU member states. However, defining the degree of sustainability aimed at is not a straightforward task. It requires detailed knowledge of the hydrogeological characteristics of the basin in question, its environmental needs, the amount of human water demand, and the opportunity to construct a proper water balance that describes the behavior of the hydrological system and estimates available water resources. An analysis of the water balance in the Selva basin (Girona, NE Spain) points to the importance of regional groundwater fluxes in satisfying current exploitation rates, and shows that regional scale approaches are often necessary to evaluate water availability. In addition, we discuss the pressures on water resources, and analyze potential actions, based on the water balance results, directed towards achieving sustainable water management in the basin.

  7. Watt and joule balances

    Science.gov (United States)

    Robinson, Ian A.

    2014-04-01

    The time is fast approaching when the SI unit of mass will cease to be based on a single material artefact and will instead be based upon the defined value of a fundamental constant—the Planck constant—h . This change requires that techniques exist both to determine the appropriate value to be assigned to the constant, and to measure mass in terms of the redefined unit. It is important to ensure that these techniques are accurate and reliable to allow full advantage to be taken of the stability and universality provided by the new definition and to guarantee the continuity of the world's mass measurements, which can affect the measurement of many other quantities such as energy and force. Up to now, efforts to provide the basis for such a redefinition of the kilogram were mainly concerned with resolving the discrepancies between individual implementations of the two principal techniques: the x-ray crystal density (XRCD) method [1] and the watt and joule balance methods which are the subject of this special issue. The first three papers report results from the NRC and NIST watt balance groups and the NIM joule balance group. The result from the NRC (formerly the NPL Mk II) watt balance is the first to be reported with a relative standard uncertainty below 2 × 10-8 and the NIST result has a relative standard uncertainty below 5 × 10-8. Both results are shown in figure 1 along with some previous results; the result from the NIM group is not shown on the plot but has a relative uncertainty of 8.9 × 10-6 and is consistent with all the results shown. The Consultative Committee for Mass and Related Quantities (CCM) in its meeting in 2013 produced a resolution [2] which set out the requirements for the number, type and quality of results intended to support the redefinition of the kilogram and required that there should be agreement between them. These results from NRC, NIST and the IAC may be considered to meet these requirements and are likely to be widely debated

  8. NASA Earth Exchange (NEX)

    Data.gov (United States)

    National Aeronautics and Space Administration — The NASA Earth Exchange (NEX) represents a new platform for the Earth science community that provides a mechanism for scientific collaboration and knowledge sharing....

  9. Earth on the Move.

    Science.gov (United States)

    Naturescope, 1987

    1987-01-01

    Provides background information on the layers of the earth, the relationship between changes on the surface of the earth and its insides, and plate tectonics. Teaching activities are included, with some containing reproducible worksheets and handouts to accompany them. (TW)

  10. EarthKAM

    Data.gov (United States)

    National Aeronautics and Space Administration — Sponsored by NASA, EarthKAM (Earth Knowledge Acquired by Middle School Students) is an educational outreach program allowing middle school students to take pictures...

  11. A New Carbonate Chemistry in the Earth's Lower Mantle

    Science.gov (United States)

    Boulard, E.; Gloter, A.; Corgne, A.; Antonangeli, D.; Auzende, A.; Perrillat, J.; Guyot, F. J.; Fiquet, G.

    2010-12-01

    The global geochemical carbon cycle involves exchange between the Earth’s mantle and the surface. Carbon (C) is recycled into the mantle via subduction and released to the atmosphere via volcanic outgassing. Carbonates are the main C-bearing minerals that are transported deep in the Earth’s mantle via subduction of the oceanic lithosphere [1]. The way C is recycled and its contribution to the lower mantle reservoir is however largely unknown [ e.g 2, 3]. In this respect, it is important to assess if carbonates can be preserved in the deep mantle, or if decarbonatation, melting or reduction play a role in the deep carbon cycle. To clarify the fate of carbonates in the deep mantle, we carried out high-pressure and high-temperature experiments up to 105 GPa and 2850 K. Natural Fe-Mg carbonates or oxide mixtures of (Mg,Fe)O + CO2 were loaded into laser heated diamond anvil cells. In situ characterizations were done by X-ray Diffraction (XRD) using synchrotron radiation at the high-pressure beamline ID27 of the European Synchrotron Radiation Facility. A focused ion beam technique was then used to prepare the recovered samples for electron energy loss spectroscopy in a dedicated scanning transmission electron microscope (EELS-STEM) and scanning transmission X-ray microscopy (STXM). In situ XRD clearly shows the transformation of the initial carbonate phase into a new Mg-Fe high pressure carbonate phase at lower mantle conditions. We also provide direct evidence for recombination of CO2 with (Mg,Fe)O to form this new carbonate structure. In addition, subsequent EELS-STEM and STXM spectroscopies carried out on recovered samples yields C K-edge and stoechiometry characteristic to this new carbonate structure. This new high pressure phase concentrates a large amount of Fe(III), as a result of redox reactions within the siderite-rich carbonate. The oxidation of iron is balanced by partial reduction of carbon into CO groups and/or diamond. These reactions may provide an

  12. A balanced team generating model

    NARCIS (Netherlands)

    van de Water, Tara; van de Water, Henny; Bukman, Cock

    2007-01-01

    This paper introduces a general team balancing model. It first summarizes existing balancing methods. It is shown that for these methods it is difficult to meet all the conditions posed by Belbin on balanced teams. This mainly is caused by the complexity of the balancing problem. A mathematical mode

  13. Capturing Near Earth Objects

    OpenAIRE

    Baoyin, Hexi; CHEN Yang; Li, Junfeng

    2011-01-01

    Recently, Near Earth Objects (NEOs) have been attracting great attention, and thousands of NEOs have been found to date. This paper examines the NEOs' orbital dynamics using the framework of an accurate solar system model and a Sun-Earth-NEO three-body system when the NEOs are close to Earth to search for NEOs with low-energy orbits. It is possible for such an NEO to be temporarily captured by Earth; its orbit would thereby be changed and it would become an Earth-orbiting object after a small...

  14. Rotary and Magnus balances

    Science.gov (United States)

    Malcolm, G. N.

    1981-01-01

    Two wind tunnel techniques for determining part of the aerodynamic information required to describe the dynamic bahavior of various types of vehicles in flight are described. Force and moment measurements are determined with a rotary-balance apparatus in a coning motion and with a Magnus balance in a high-speed spinning motion. Coning motion is pertinent to both aircraft and missiles, and spinning is important for spin stabilized missiles. Basic principles of both techniques are described, and specific examples of each type of apparatus are presented. Typical experimental results are also discussed.

  15. Application of Balanced Scorecard

    OpenAIRE

    Langpaulová, Irena

    2011-01-01

    The concept of the Balanced Scorecard taking a part in the strategic management of a company, is a main focus of this thesis. There are the theoretical and methodological parts of the Balanced Scorecard characterized individually, as well as the development and the history of this concept. This thesis is dealing with a draft of the practical implementation of the mentioned methods. The practical part of the thesis is following the theoretical introduction where the practical part is focused o...

  16. Finding Your Balance

    CERN Document Server

    (CCL), Center for Creative Leadership; Patterson, Gordon

    2011-01-01

    Balance isn't an issue of time, but an issue of choice. It's about living your values by aligning your behavior with what you believe is really important. Aligning your behavior with your values is much like any other developmental experience; the basic process involves assessment, challenge, and support. You need to determine where you are, define where you want to go, and then put into place the tools you need to get there.Balance is about more than how you spend your time. It's about how you live your life. It's about recognizing that you have control over the choices you make and aligning

  17. Fleksibilitet og balance

    OpenAIRE

    2014-01-01

    Fleksibilitet og balance Dette projekt undersøger, hvordan arbejdstidsmæssig fleksibilitet påvirker medarbejderens individuelle balance mellem arbejde og privatliv, og om en ændring af dennes mindset kan forbedre balancen. Centralt i projektet er en afdækning af fordele og ulemper ved den arbejdstidsmæssige fleksibilitet. I forlængelse heraf er det interessant, hvordan disse fordele og ulemper påvirker balancen mellem arbejde og privatliv. Ydermere er det interessant om den enkelte medarb...

  18. Yin-Yang Balancing

    DEFF Research Database (Denmark)

    Li, Peter Ping

    The potential contribution of the Eastern frame of Yin-Yang Balancing lies in the mindset of "either/and", in contrast to Aristotle's either/or logic and Hegel's "both/or". Implications of this either/and thinking for science and management will be explored.......The potential contribution of the Eastern frame of Yin-Yang Balancing lies in the mindset of "either/and", in contrast to Aristotle's either/or logic and Hegel's "both/or". Implications of this either/and thinking for science and management will be explored....

  19. Design and experiment of balance and low-loss air allotter in air pressure maize precision planter%气压式玉米精量播种机均匀低损配气机构设计与试验

    Institute of Scientific and Technical Information of China (English)

    殷小伟; 杨丽; 张东兴; 崔涛; 韩丹丹; 张天亮; 虞异茗

    2016-01-01

    allotter consisted of coaxial inlet and outlet and a concave-convex combined curve. Through the dimension driven in SolidWorks, the shape of the concave-convex combined curve could be ensured. An optimal structure with related parameters was estimated finally through the simulation of different types of allotters with different shapes of concave-convex combined curve. The experiment and simulation results indicated that the length of the connection segment of the allotter and the ratio of concave curve to outward curve were 2 significant parameters. Field experiment was conducted with 2 different types of allotters installed on air pressure maize precision planter to validate the result of simulation. The pressure and velocity of the balance and low-loss air allotter were measured by air flow meter KA33 made by KANOMAX. Results proved that the performance of the balance and low-loss air allotter was better than that of other widely used allotters. Comparative experiment showed that the rate of pressure loss of the designed allotter was kept within 10% under different working pressures, while the loss of another allotter was over 30%. The pressure consistency variation coefficient of 4-row seed metering device was less than 4%. The research shows that the allotter cannot be ignored in the research of maize precision planter. Appropriate structure of air allotter can significantly reduce energy consumption and ensure uniform air pressure when the planter works.

  20. Numerical Simulation on Piston Buffering Characteristics of Pressure-balanced Underwater Torpedo Launch System%液压平衡式水下鱼雷发射系统活塞缓冲特性数值仿真

    Institute of Scientific and Technical Information of China (English)

    张孝芳; 胡坤; 由文立

    2011-01-01

    For researching the shock vibration resulted from the water cylinder piston buffering of the underwater torpedo launch system, computational fluid dynamics ( CFD) simulation is conducted to study the piston buffering characteristics. One-dimensional and CFD methods are combined in the simulation.The thermodynamic models of air bottle and cylinder, and the kinetic model of piston and weapon are described by using ordinary differential equations ( ODE ) , and they are solved by using four-order RungeKutta method. The seawater flows in cylinder, launch chamber and launch tube are solved by using CFD method. The applied force and velocity of the torpedo are used as coupling variables to account for the interaction between fluid and solids. The simulation results show that, at the end of the launch process, the pressure surges in piston buffering mechanism will generate shocks to submarine structure. To reduce the shock vibration and noise of underwater torpedo launch, the buffering mechanism should be redesigned optimally.%为研究水下鱼雷发射系统水缸活塞缓冲阶段对系统造成的冲击振动影响,采用计算流体力学(CFD)仿真对其缓冲机构特性进行研究.仿真中采用一维仿真与CFD仿真相结合的方法.气瓶与气缸热力学模型、活塞及鱼雷动力学模型均用一维常微分方程(ODE)描述,采用四阶龙格库塔法求解;包括水缸、发射水舱和发射管的整个海水区域的流体流动采用CFD方法求解.一维模型和流体计算模型之间用活塞与鱼雷的受力和运动速度作为中间变量相联系,从而实现流体与固体之间的耦合.仿真结果表明,发射结束时缓冲座内海水瞬时压力过高会对潜艇结构造成较大冲击,为降低鱼雷发射冲击振动与噪声必须对活塞缓冲机构进行优化.

  1. Comment on: ``Experimental evidence for the pressure dependence of fission track annealing in apatite'' by A.S. Wendt et al. [Earth Planet. Sci. Lett. 201 (2002) 593-607

    Science.gov (United States)

    Kohn, B. P.; Belton, D. X.; Brown, R. W.; Gleadow, A. J. W.; Green, P. F.; Lovering, J. F.

    2003-10-01

    The pressure experiments reported by Wendt et al. are cast in such a way as to question the fundamental basis underpinning apatite fission track thermochronology, implying the possibility of a large systematic error in previous interpretations. We find however, that the study is severely compromised by fundamental errors in both experimental design and execution, as well as lacking in consideration of a substantial body of previous work in the area of fission track annealing studies. Wendt et al. have not attempted to extrapolate the results of their experiments to geologically relevant heating times and temperatures. This has been the fundamental test that all previous annealing models have had to pass. Their study clearly fails this test. Moreover, if significant pressure dependence does exist then it is implicit in existing, deep borehole-consistent annealing models. Whilst such models are interpolated in terms of temperature, the borehole test means that they also accommodate any other factors, which correlate with temperature, including pressure. The implications of the results reported by Wendt et al. have been overstated. Far from being "intimidating", we find that they have little relevance either to previous studies of apatite fission track annealing and extrapolations based on them, or to the routine application of fission track analysis to elucidate thermal history information under geological conditions.

  2. Frihed, anerkendelse og balance

    DEFF Research Database (Denmark)

    Anker, Thomas Boysen

    2008-01-01

    Artiklen argumenterer for, at selv ikke den absolut mest familievenlige arbejdsplads vil kunne løse det psykologiske problem med at skabe balance mellem familie og arbejdsliv, fordi ubalancen grundlæggende handler om en anerkendelseskonflikt, som individet ikke altid selv er interesseret i at komme...

  3. Ballet Balance Strategies

    DEFF Research Database (Denmark)

    Pedersen, Camilla; Erleben, Kenny; Sporring, Jon

    2006-01-01

    Animating physically realistic human characters is challenging, since human observers are highly tuned to recognize human cues such as emotion and gender from motion patterns. The main contribution of this paper is a new model firmly based on biomechanics, which is used to animate balance and basic...

  4. Strategic Balanced Scorecard Simulation

    DEFF Research Database (Denmark)

    Nielsen, Steen; Nielsen, Erland Hejn

    2012-01-01

    The purpose of this article is to show how a System Dynamics Modelling approach can be integrated into the Balanced Scorecard (BSC) for a case company with special focus on the handling of causality in a dynamic perspective. The case company’s BSC model includes five perspectives and a number...

  5. Balancing beyond the horizon?

    DEFF Research Database (Denmark)

    Kluth, Michael Friederich; Pilegaard, Jess

    2011-01-01

    The present article seeks to make sense of recent European Union (EU) naval capability changes by applying neo-realist theory to the EU as a collective actor in the global balance of power. The paper compares two different strands of neorealist theory by deducing key predictions about the expecte...

  6. Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs

    Science.gov (United States)

    Bloomberg, Jacob; Reschke, Millard; Mulavara, Ajitkumar; Wood, Scott; Serrador, Jorge; Fiedler, Matthew; Kofman, Igor; Peters, Brian T.; Cohen, Helen

    2012-01-01

    Crewmembers returning from long-duration space flight face significant challenges due to the microgravity-induced inappropriate adaptations in balance/ sensorimotor function. The Neuroscience Laboratory at JSC is developing a method based on stochastic resonance to enhance the brain s ability to detect signals from the balance organs of the inner ear and use them for rapid improvement in balance skill, especially when combined with balance training exercises. This method involves a stimulus delivery system that is wearable/portable providing imperceptible electrical stimulation to the balance organs of the human body. Stochastic resonance (SR) is a phenomenon whereby the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. This phenomenon of SR is based on the concept of maximizing the flow of information through a system by a non-zero level of noise. Application of imperceptible SR noise coupled with sensory input in humans has been shown to improve motor, cardiovascular, visual, hearing, and balance functions. SR increases contrast sensitivity and luminance detection; lowers the absolute threshold for tone detection in normal hearing individuals; improves homeostatic function in the human blood pressure regulatory system; improves noise-enhanced muscle spindle function; and improves detection of weak tactile stimuli using mechanical or electrical stimulation. SR noise has been shown to improve postural control when applied as mechanical noise to the soles of the feet, or when applied as electrical noise at the knee and to the back muscles.

  7. 负压脉冲可调式平衡吸乳器用于产后早期辅助开奶效果观察%Effects Observation of Negative Pressure Pulse Adjustable Balance Breast Pump using in Early Milk Opening after Postpartum

    Institute of Scientific and Technical Information of China (English)

    侯振平

    2014-01-01

    To investigate the clinical effects of negative pulse adjustable balance breast pump using in early milk opening after postpartum.Methods:250 cases with no breast-feeding contraindications were randomized,130 cases using negative pressure pulse adjustable balance breast pump maternal were distributed into observation group,and 120 cases given routine nursing care were distributed into control group.Results:The degree of breast pain was significantly reduced in observation group than control group (P<0.01),ductal patency time was significantly shorter in observation group (P<0.05),the success rate of breast feeding improved (P<0.05). Conclusion:Negative pulse adjustable balance breast pump using in early milk opening after postpartum can effectively reduce the dredging breast duct,breast pain,improve the success rate of breast feeding.%目的:探讨负压脉冲可调式平衡吸乳器用于产后早期辅助开奶的临床效果。方法:无母乳喂养禁忌证初产妇250例随机分组,使用负压脉冲可调式平衡吸乳器产妇130例为观察组,仅给予产后常规护理产妇120例为对照组。结果:观察组较对照组乳房胀痛程度明显减轻(P<0.01),乳腺管通畅时间缩短(P<0.05)、母乳喂养成功率提高(P<0.05)。结论:产后早期使用负压脉冲可调式平衡吸乳器辅助开奶,可及时有效疏通乳腺管,减少乳房胀痛的发生,有利于提高母乳喂养成功率。

  8. Ocular perfusion pressure in glaucoma.

    Science.gov (United States)

    Costa, Vital P; Harris, Alon; Anderson, Douglas; Stodtmeister, Richard; Cremasco, Fernanda; Kergoat, Helene; Lovasik, John; Stalmans, Ingborg; Zeitz, Oliver; Lanzl, Ines; Gugleta, Konstantin; Schmetterer, Leopold

    2014-06-01

    This review article discusses the relationship between ocular perfusion pressure and glaucoma, including its definition, factors that influence its calculation and epidemiological studies investigating the influence of ocular perfusion pressure on the prevalence, incidence and progression of glaucoma. We also list the possible mechanisms behind this association, and discuss whether it is secondary to changes in intraocular pressure, blood pressure or both. Finally, we describe the circadian variation of ocular perfusion pressure and the effects of systemic and topical medications on it. We believe that the balance between IOP and BP, influenced by the autoregulatory capacity of the eye, is part of what determines whether an individual will develop optic nerve damage. However, prospective, longitudinal studies are needed to better define the role of ocular perfusion pressure in the development and progression of glaucoma.

  9. 基于离散元颗粒抗转模型的平移刚性挡墙被动土压力分析%Distinct element simulation of passive earth pressure against a translating rigid wall using a rolling resistance contact model

    Institute of Scientific and Technical Information of China (English)

    蒋明镜; 贺洁; 刘芳

    2012-01-01

    A model considering rolling resistance in particles is introduced into the distinct element method (DEM) for analyzing the earth pressure against a rigid wall subjected to translation movements in the passive state. The evolution of earth pressure with the wall displacement is analyzed together with micro mechanical parameters by comparing the cases with and without considering the rolling resistance of particles in the granular backfill. Results show that the earth pressure increases linearly with the increase of the wall depth regardless of the effect of rolling resistance; and the total thrust acts at approximately one third of the wall height from the base of the wall in both cases. The increase of the resultant earth pressure with displacement is more prominent in the case considering rolling resistance than that neglecting the rolling resistance. The result considering rolling resistance is more close to the classic Coulomb's solution. According to the field of average pure rotation rate, the velocity of soil particles adjacent to the base of the rigid wall is larger, implying a quick energy dissipation taking place at that region, and it becomes even larger in the case considering the rolling resistance than that in the case without considering the rolling resistance.%将颗粒抗转动模型引入离散元程序中,模拟了砂性填土刚性挡土墙平移过程中的被动土压力发展过程,对比分析了考虑和不考虑抗转两种情况下墙后土压力随位移的变化规律及墙后填土微观物理量的变化规律,揭示了颗粒抗转动能力对墙后土压力大小和分布的影响.研究结果表明,不管是否考虑颗粒抗转动作用,被动土压力沿墙深基本呈线性分布,且合力作用点维持在距墙底1/3墙高处,但考虑颗粒抗转动作用时总土压力随位移量增大的幅度更加明显,且模拟结果更接近Coulomb 理论解.平均纯转动率的分析结果表明,挡墙平移时墙底处颗粒转动

  10. CMEs at Earth and Mars

    Science.gov (United States)

    Falkenberg, T. V.; Vennerstrom, S.; Taktakishvili, A.; Pulkkinen, A.; Brain, D. A.; Delory, G. T.; Mitchell, D.

    2010-12-01

    We perform a survey of the longitudinal extent and general nature of fast Coronal Mass Ejections (CMEs) identifiable at both Mars and Earth and use the ENLIL Magneto-Hydro-Dynamic model to replicate data for the CMEs at both planets. We have chosen 18 fast CMEs with initial velocities, according to the SOHO/LASCO catalogue, between 1200 and 2700 km/s in the period 2001-2003. CME arrival is identified at Earth by sharp increases in velocity, density and magnetic field strength in data compiled from the ACE,WIND and Geotail spacecraft, while CME arrival at Mars is identified by a large increase in magnetic field strength and by increases in the background countrate of the Electron Reflectometer (ER) instrument on Mars Global Surveyor (MGS). The ER backgrounds are used to determine the presence of Solar Energetic Particles related to fast CMEs. We run ENLIL using two different sets of input parameters, both estimated from SOHO/LASCO images, but one set is estimated manually and one set is estimated using an automated method. Specific parameters of interest are arrival time, longitudinal span, and propagation direction of the CMEs. At Earth the velocity, density and magnetic field strength are compared to Omni data, while at Mars the solar wind dynamic pressure is compared to an upstream pressure proxy estimated from magnetic field data from MGS. A qualitative estimate of the usefulness of ENLIL in CME modeling will be given, as well as a comparison of the effectiveness of the two methods used to find input parameters for the model.

  11. Balance in Parkinson's disease patients changing the visual input

    OpenAIRE

    Suarez,Hamlet; Geisinger, Dario; Ferreira,Enrique D.; Nogueira,Santiago; Arocena,Sofia; Roman,Cecilia San; Suarez,Alejo

    2011-01-01

    The description of the postural responses in Parkinson's disease patients when visual information changes from a stable to a moving visual field analyzing the impact on balance in these patients. METHODS (CLINICAL): Limits of Stability, Body center of pressure and balance functional reserve were measured by means of the force platform in 24 Parkinson´s patients in stages 1 and 2 of the Boher classification and 19 volunteers as a control group. Both groups were stimulated with 1-Static visual ...

  12. Uderstanding Snowball Earth Deglaciation

    Science.gov (United States)

    Abbot, D. S.

    2012-12-01

    Earth, a normally clement planet comfortably in its star's habitable zone, suffered global or nearly global glaciation at least twice during the Neoproterozoic era (at about 635 and 710 million years ago). Viewed in the context of planetary evolution, these pan-global glaciations (Snowball Earth events) were extremely rapid, lasting only a few million years. The dramatic effect of the Snowball Earth events on the development of the planet can be seen through their link to rises in atmospheric oxygen and evolutionary innovations. These potential catastrophes on an otherwise clement planet can be used to gain insight into planetary habitability more generally. Since Earth is not currently a Snowball, a sound deglaciation mechanism is crucial for the viability of the Snowball Earth hypothesis. The traditional deglaciation mechanism is a massive build up of CO2 due to reduced weathering during Snowball Earth events until tropical surface temperatures reach the melting point. Once initiated, such a deglaciation might happen on a timescale of only dozens of thousands of years and would thrust Earth from the coldest climate in its history to the warmest. Therefore embedded in Snowball Earth events is an even more rapid and dramatic environmental change. Early global climate model simulations raised doubt about whether Snowball Earth deglaciation could be achieved at a CO2 concentration low enough to be consistent with geochemical data, which represented a potential challenge to the Snowball Earth hypothesis. Over the past few years dust and clouds have emerged as the essential missing additional processes that would allow Snowball Earth deglaciation at a low enough CO2 concentration. I will discuss the dust and cloud mechanisms and the modeling behind these ideas. This effort is critical for the broader implications of Snowball Earth events because understanding the specific deglaciation mechanism determines whether similar processes could happen on other planets.

  13. The Earth's Magnetic Field

    OpenAIRE

    Edda Lína Gunnarsdóttir 1988

    2012-01-01

    The Earth's magnetic field is essential for life on Earth, as we know it, to exist. It forms a magnetic shield around the planet, protecting it from high energy particles and radiation from the Sun, which can cause damage to life, power systems, orbiting satellites, astronauts and spacecrafts. This report contains a general overview of the Earth's magnetic field. The different sources that contribute to the total magnetic field are presented and the diverse variations in the field are describ...

  14. In the balance

    DEFF Research Database (Denmark)

    Kluth, Michael Friederich; Pilegaard, Jess

    The present paper seeks to make sense of recent EU naval capability changes by applying neo-realist theory on the EU as an international actor in the global balance of power. The paper compares three different strands of Neo-realist theory by deducting key predictions about the expected defense...... posture of the Union and the expected changes in naval capabilities. The predictions are subsequently held up against recent data on naval military build-up in the EU. The paper argues that the observed patterns are best explained not as bandwagoning with the United States, but as a long-term balancing...... strategy aimed at bolstering the autonomy and international influence of the Union, vis-à-vis other major powers, including the United States....

  15. The balanced scorecard: sustainable performance assessment for forensic laboratories.

    Science.gov (United States)

    Houck, Max; Speaker, Paul J; Fleming, Arron Scott; Riley, Richard A

    2012-12-01

    The purpose of this article is to introduce the concept of the balanced scorecard into the laboratory management environment. The balanced scorecard is a performance measurement matrix designed to capture financial and non-financial metrics that provide insight into the critical success factors for an organization, effectively aligning organization strategy to key performance objectives. The scorecard helps organizational leaders by providing balance from two perspectives. First, it ensures an appropriate mix of performance metrics from across the organization to achieve operational excellence; thereby the balanced scorecard ensures that no single or limited group of metrics dominates the assessment process, possibly leading to long-term inferior performance. Second, the balanced scorecard helps leaders offset short term performance pressures by giving recognition and weight to long-term laboratory needs that, if not properly addressed, might jeopardize future laboratory performance.

  16. Capturing near-Earth asteroids around Earth

    Science.gov (United States)

    Hasnain, Zaki; Lamb, Christopher A.; Ross, Shane D.

    2012-12-01

    The list of detected near-Earth asteroids (NEAs) is constantly growing. NEAs are likely targets for resources to support space industrialization, as they may be the least expensive source of certain needed raw materials. The limited supply of precious metals and semiconducting elements on Earth may be supplemented or even replaced by the reserves floating in the form of asteroids around the solar system. Precious metals make up a significant fraction NEAs by mass, and even one metallic asteroid of ˜1km size and fair enrichment in platinum-group metals would contain twice the tonnage of such metals already harvested on Earth. There are ˜1000 NEAs with a diameter of greater than 1 km. Capturing these asteroids around the Earth would expand the mining industry into an entirely new dimension. Having such resources within easy reach in Earth's orbit could provide an off-world environmentally friendly remedy for impending terrestrial shortages, especially given the need for raw materials in developing nations. In this paper, we develop and implement a conceptually simple algorithm to determine trajectory characteristics necessary to move NEAs into capture orbits around the Earth. Altered trajectories of asteroids are calculated using an ephemeris model. Only asteroids of eccentricity less than 0.1 have been studied and the model is restricted to the ecliptic plane for simplicity. We constrain the time of retrieval to be 10 years or less, based on considerations of the time to return on investment. For the heliocentric phase, constant acceleration is assumed. The acceleration required for transporting these asteroids from their undisturbed orbits to the sphere of influence of the Earth is the primary output, along with the impulse or acceleration necessary to effect capture to a bound orbit once the Earth's sphere of influence is reached. The initial guess for the constant acceleration is provided by a new estimation method, similar in spirit to Edelbaum's. Based on the

  17. Geochemistry of Rare Earth Elements in Aktishikan Gold Deposit, Xinjiang

    Institute of Scientific and Technical Information of China (English)

    袁峰; 周涛发; 岳书仓

    2002-01-01

    The characteristics and the models of rare earth elements in the geolo gical bodies and the hydrothermal water balanced with the adamellite were compre h ensively studied in Aktishikan gold deposit,Nurt area of Altay,Xinjiang.And th e behavior of rare earth elements during metasomatic alteration was discussed by using the isocon method of Grant.The results show that the rare earth elements a re inert during metasomatic alteration,the hydrothermal water has no relation t o the magmatic water,and the gold material sources mainly stem from the wall rock.

  18. Getting the Balance Right

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    In the next five years China will balance economic growth and improving the living standards of its people by Liu Wei IT was widely reported that the chaos in some Middle East and North African countries were results of the inadequate efforts in improving people’s livelihood, a fundamental aspect of social stability. In early March,China held its annual sessions of the National People’s

  19. Balancing innovation and evidence.

    Science.gov (United States)

    Pilcher, Jobeth W

    2015-01-01

    Nurse educators are encouraged to use evidence to guide their teaching strategies. However, evidence is not always available. How can educators make decisions regarding strategies when data are limited or absent? Where do innovation and creativity fit? How can innovation be balanced with evidence? This article provides a discussion regarding other sources of evidence, such as extrapolations, theories and principles, and collective expertise. Readers are encouraged to review the options and then analyze how they might be applied to innovation in education.

  20. Modeling the surface temperature of Earth-like planets

    CERN Document Server

    Vladilo, G; Murante, G; Filippi, L; Provenzale, A

    2015-01-01

    We introduce a novel Earth-like planet surface temperature model (ESTM) for habitability studies based on the spatial-temporal distribution of planetary surface temperatures. The ESTM adopts a surface Energy Balance Model complemented by: radiative-convective atmospheric column calculations, a set of physically-based parameterizations of meridional transport, and descriptions of surface and cloud properties more refined than in standard EBMs. The parameterization is valid for rotating terrestrial planets with shallow atmospheres and moderate values of axis obliquity (epsilon >= 45^o). Comparison with a 3D model of atmospheric dynamics from the literature shows that the equator-to-pole temperature differences predicted by the two models agree within ~5K when the rotation rate, insolation, surface pressure and planet radius are varied in the intervals 0.5 <= Omega/Omega_o <= 2, 0.75 <= S/S_o <= 1.25, 0.3 <= p/(1 bar) <= 10, and 0.5 <= R/R_o <= 2, respectively. The ESTM has an extremely l...

  1. Implementace metody Balanced Scorecard

    OpenAIRE

    Neuwirth, Pavel

    2014-01-01

    Diplomová práce je zaměřena na hodnocení výkonnosti společnosti pomocí metody Balanced Scorecard. Teoretická část práce popisuje východiska měření výkonnosti, metody Balanced Scorecard a postup při její implementaci. Analytická část vychází z teoretických poznatků z první části a hodnotí situaci společnosti finanční analýzou poměrových ukazatelů, strategickou analýzou a následným sestavením návrhu implementace metody Balanced Scorecard v konkrétní společnosti. Thesis is focused on evaluati...

  2. Effects of insoles contact on static balance.

    Science.gov (United States)

    Shin, Ju Yong; Ryu, Young Uk; Yi, Chae Woo

    2016-04-01

    [Purpose] This study examined the effect of the degree of the contact area between the insoles and soles on static balance. [Subjects and Methods] Thirteen healthy male and female adults voluntarily participated. All of the subjects wore three different types of insoles (no orthotic insole, partial contact, full contact) in the present experiment. The subjects were instructed to place both feet parallel to each other and maintain static balance for 30 seconds. Center of pressure parameters (range, total distance, and mean velocity) were analyzed. [Results] The results show that the anteroposterior range and mediolateral (ML) total distance and velocity decreased when orthotic insoles with partial contact or full contact were used in comparison to when a flat insole (no orthotic insole) was used. Also, the ML range and total distance were lower with full contact than in the other two conditions. These results indicate that static balance improves as the degree of contact between the soles and insoles increases. [Conclusion] The results of this study suggests that using insoles with increased sole contact area would improve static balance ability.

  3. Lunar origin from impact on the Earth

    Science.gov (United States)

    Stevenson, D. J.

    1984-01-01

    All theories of lunar origin involve events or processes which seemingly have low efficiencies or low probabilities or both. An impact-triggered fission lunar origin is presented. If the impact ejecta (a mixture of target and projectile) leave the impact site ballistically and are subsequently acted upon only by the gravity field of a spherical Earth, then the ejecta either reimpacts the Earth or escapes on a hyperbolic trajectory. Hence the need for a second burn. Three possible resolutions are considered: pressure gradient acceleration, non-central gravity, and viscous spreading.

  4. Homeostatic tendencies of the earth's atmosphere

    Science.gov (United States)

    Lovelock, J. E.; Margulis, L.

    1974-01-01

    The concept is developed that the atmosphere of the earth flows in a closed system controlled by and for the biosphere. The environmental factors delimiting the biosphere are examined. It is found that neither oxygen nor pressure per se limit the distribution of life as a whole. Rather the major physical variables determining the distribution of organisms are solar radiation, temperature, water abundance, and the concentrations of hydrogen and other ions and elements. An attempt is made to model temperature and atmospheric composition of a lifeless earth.

  5. Raman Spectroscopy at High Pressures

    Directory of Open Access Journals (Sweden)

    Alexander F. Goncharov

    2012-01-01

    Full Text Available Raman spectroscopy is one of the most informative probes for studies of material properties under extreme conditions of high pressure. The Raman techniques have become more versatile over the last decades as a new generation of optical filters and multichannel detectors become available. Here, recent progress in the Raman techniques for high-pressure research and its applications in numerous scientific disciplines including physics and chemistry of materials under extremes, earth and planetary science, new materials synthesis, and high-pressure metrology will be discussed.

  6. On output measurements via radiation pressure

    DEFF Research Database (Denmark)

    Leeman, S.; Healey, A.J.; Forsberg, F.;

    1990-01-01

    It is shown, by simple physical argument, that measurements of intensity with a radiation pressure balance should not agree with those based on calorimetric techniques. The conclusion is ultimately a consequence of the circumstance that radiation pressure measurements relate to wave momentum, whi...

  7. Relationships between fear of falling, balance confidence, and control of balance, gait, and reactive stepping in individuals with sub-acute stroke.

    Science.gov (United States)

    Schinkel-Ivy, Alison; Inness, Elizabeth L; Mansfield, Avril

    2016-01-01

    Fear of falling is common in individuals with stroke; however, the associations between fear of falling, balance confidence, and the control of balance and gait are not well understood for this population. This study aimed to determine whether, at the time of admission to in-patient rehabilitation, specific features of balance and gait differed between individuals with stroke who did and did not report fear of falling, and whether these features were related to balance confidence. Individuals with stroke entering in-patient rehabilitation were asked if they were afraid of falling, and completed the Activities-Specific Balance Confidence Scale. Participants performed quiet standing, gait, and reactive stepping tasks, and specific measures were extracted for each (quiet standing: centre of pressure amplitude, between-limb synchronization, and Romberg quotients; gait: walking velocity, double support time, and variability measures; reactive stepping: number of steps, frequency of grasp reactions, and frequency of assists). No significant differences were identified between individuals with and without fear of falling. Balance confidence was negatively related to centre of pressure amplitude, double support time, and step time variability, and positively related to walking velocity. Low balance confidence was related to poor quiet standing balance control and cautious behavior when walking in individuals with sub-acute stroke. While the causal relationship between balance confidence and the control of balance and gait is unclear from the current work, these findings suggest there may be a role for interventions to increase balance confidence among individuals with stroke, in order to improve functional mobility.

  8. Introducing Earth's Orbital Eccentricity

    Science.gov (United States)

    Oostra, Benjamin

    2015-01-01

    Most students know that planetary orbits, including Earth's, are elliptical; that is Kepler's first law, and it is found in many science textbooks. But quite a few are mistaken about the details, thinking that the orbit is very eccentric, or that this effect is somehow responsible for the seasons. In fact, the Earth's orbital eccentricity is…

  9. Dietary Restriction and Nutrient Balance in Aging

    Directory of Open Access Journals (Sweden)

    Júlia Santos

    2016-01-01

    Full Text Available Dietary regimens that favour reduced calorie intake delay aging and age-associated diseases. New evidences revealed that nutritional balance of dietary components without food restriction increases lifespan. Particular nutrients as several nitrogen sources, proteins, amino acid, and ammonium are implicated in life and healthspan regulation in different model organisms from yeast to mammals. Aging and dietary restriction interact through partially overlapping mechanisms in the activation of the conserved nutrient-signalling pathways, mainly the insulin/insulin-like growth factor (IIS and the Target Of Rapamycin (TOR. The specific nutrients of dietary regimens, their balance, and how they interact with different genes and pathways are currently being uncovered. Taking into account that dietary regimes can largely influence overall human health and changes in risk factors such as cholesterol level and blood pressure, these new findings are of great importance to fully comprehend the interplay between diet and humans health.

  10. Solid Earth: Introduction

    Science.gov (United States)

    Rummel, R.

    1991-10-01

    The principles of the solid Earth program are introduced. When considering the study of solid Earth from space, satellites are used as beacons, inertial references, free fall probes and carrying platforms. The phenomenon measured by these satellites and the processes which can be studied as a result of these measurements are tabulated. The NASA solid Earth program focusses on research into surface kinematics, Earth rotation, land, ice, and ocean monitoring. The ESA solid Earth program identifies as its priority the Aristoteles mission for determining the gravity and magnetic field globally, with high spatial resolution and high accuracy. The Aristoteles mission characteristics and goals are listed. The benefits of the improved gravity information that will be provided by this mission are highlighted. This information will help in the following research: geodesy, orbit mechanics, geodynamics, oceanography, climate sea level, and the atmosphere.

  11. Can balance trampoline training promote motor coordination and balance performance in children with developmental coordination disorder?

    Science.gov (United States)

    Giagazoglou, Paraskevi; Sidiropoulou, Maria; Mitsiou, Maria; Arabatzi, Fotini; Kellis, Eleftherios

    2015-01-01

    The present study aimed to examine movement difficulties among typically developing 8- to 9-year-old elementary students in Greece and to investigate the possible effects of a balance training program to those children assessed with Developmental Coordination Disorder (DCD). The Body Coordination Test for Children (BCTC; Körperkoordinationstest fur Kinder, KTK, Kiphard & Schilling, 1974) was chosen for the purposes of this study and 20 children out of the total number of 200, exhibited motor difficulties indicating a probable DCD disorder. The 20 students diagnosed with DCD were equally separated into two groups where each individual of the experimental group was paired with an individual of the control group. The intervention group attended a 12-week balance training program while students of the second - control group followed the regular school schedule. All participants were tested prior to the start and after the end of the 12-week period by performing static balance control tasks while standing on an EPS pressure platform and structured observation of trampoline exercises while videotaping. The results indicated that after a 12-week balance training circuit including a trampoline station program, the intervention group improved both factors that were examined. In conclusion, balance training with the use of attractive equipment such as trampoline can be an effective intervention for improving functional outcomes and can be recommended as an alternative mode of physical activity.

  12. Virtual Acts of Balance!

    DEFF Research Database (Denmark)

    Madsen, Anders Koed

    2013-01-01

    improve 'knowledge-democracy' in different ways. The paper denotes such portals 'virtual technologies of knowledge management' and it uses the documental data as a window to analyze and discuss the infrastructural choices of such portals. The analysis is grounded in theories related to 'Social....... It is especially emphasized how technical web-ontologies implicitly carries with them deeper philosophical ontologies about phanomena such as 'politic', 'scientific intentionality' and 'freedom'. The compromise between these technical influences and the social intentions is described as a 'virtual act of balance...

  13. Balanced Topological Field Theories

    Science.gov (United States)

    Dijkgraaf, R.; Moore, G.

    We describe a class of topological field theories called ``balanced topological field theories''. These theories are associated to moduli problems with vanishing virtual dimension and calculate the Euler character of various moduli spaces. We show that these theories are closely related to the geometry and equivariant cohomology of ``iterated superspaces'' that carry two differentials. We find the most general action for these theories, which turns out to define Morse theory on field space. We illustrate the constructions with numerous examples. Finally, we relate these theories to topological sigma-models twisted using an isometry of the target space.

  14. Balanced Topological Field Theories

    CERN Document Server

    Dijkgraaf, R

    1997-01-01

    We describe a class of topological field theories called ``balanced topological field theories.'' These theories are associated to moduli problems with vanishing virtual dimension and calculate the Euler character of various moduli spaces. We show that these theories are closely related to the geometry and equivariant cohomology of ``iterated superspaces'' that carry two differentials. We find the most general action for these theories, which turns out to define Morse theory on field space. We illustrate the constructions with numerous examples. Finally, we relate these theories to topological sigma-models twisted using an isometry of the target space.

  15. Kin Selection - Mutation Balance

    DEFF Research Database (Denmark)

    Dyken, J. David Van; Linksvayer, Timothy Arnold; Wade, Michael J.

    2011-01-01

    selection-mutation balance, which provides an evolutionary null hypothesis for the statics and dynamics of cheating. When social interactions have linear fitness effects and Hamilton´s rule is satisfied, selection is never strong enough to eliminate recurrent cheater mutants from a population, but cheater...... lineages are transient and do not invade. Instead, cheating lineages are eliminated by kin selection but are constantly reintroduced by mutation, maintaining a stable equilibrium frequency of cheaters. The presence of cheaters at equilibrium creates a "cheater load" that selects for mechanisms of cheater...

  16. Production Balance of Ship Erection

    Institute of Scientific and Technical Information of China (English)

    JIANG Ru-hong; TAN Jia-hua; LIU Cun-gen

    2008-01-01

    A network plan model of ship erection was established based on the network planning technologyand the work-package breakdown system. The load-oriented production control method was introduced to buildup a throughput diagram model thus it is possible to describe the ship erection process numerically. Based onthe digitaiized models some cases of production balance of ship erection were studied and three balance indexeswere put forward, they are the load balance rate, the input manpower balance rate and the maximum gantrycrane operating times. Such an analytic method based on the balance evaluation is the important foundationfor digitization and intelligentization of shipyard production management.

  17. Sensory deprivation and balance control in idiopathic scoliosis adolescent.

    Science.gov (United States)

    Simoneau, Martin; Richer, Nadia; Mercier, Pierre; Allard, Paul; Teasdale, Nomand

    2006-04-01

    Balance control is influenced by the availability and integrity of sensory inputs as well as the ability of the balance control mechanisms to tailor the corrective action to the gravitational torque. In this study, to challenge balance control, visual and ankle proprioceptive information were perturbed (eyes closed and/or tendon vibration). We masked sensory inputs in order: (1) to test the hypothesis that adolescent idiopathic scoliosis (AIS), compared to healthy adolescent, relies more on ankle proprioception and/or visual inputs to regulate balance and (2) to determine whether it is the variation or the amplitude of the balance control commands of AIS that leads to greater body sway oscillations during sensory deprivation. By manipulating the availability of the sensory inputs and measuring the outcomes, center of pressure (CP) range and velocity variability, we could objectively determine the cost of visual and/or ankle proprioception deprivation on balance control. The CP range was larger and the root mean square (RMS) of the CP velocity was more variable for AIS than for control participants when ankle proprioception was perturbed. This was observed regardless of whether vision was available or not. The analysis of the sway density curves revealed that the amplitude rather than the variation of the balance control commands was related to a larger CP range and greater RMS CP velocity for AIS. The present results suggest that AIS, compared to control participants, relies much more on ankle proprioception to control the amplitude of the balance control commands.

  18. People, poverty and the Earth Summit.

    Science.gov (United States)

    Wheeler, J

    1992-01-01

    UNCED is about human beings managing their affairs so that all can achieve a reasonably good life without destroying the life-supporting environment. Currently human activities are approaching an upset of environmental balance through production of greenhouse gases, depletion of the ozone layer, and reduction of natural resources. Equity is the right to a decent life for the current human population of 5.5 billion and the future 10 billion expected within the next 50 years. A minimum use of environmental space/person is required. The Earth Summit will be a broad statement of environmental policy. Agenda 21 includes 115 action programs within 40 chapters. Separate conventions will be held on climate and biodiversity. The secretariat of UNCED has been working primarily with Agenda 21. Population issues are emphasized in Chapter 5 ("Demographic Dynamics and Sustainability") of the first section in Agenda 21 on Social and Economic Dimensions. The program areas include 1) research on the links between population, the environment, and development; 2) formulation by governments of integrated national policies on environment and development, which account for demographic trends, and promotion of population literacy; and 3) implementation of local level programs to ensure access to education and information and services in order to plan families freely and responsibly. Increases in funding for the population program are anticipated to be US $9 billion by the year 2000 and about US $7 billion/year until then. The year 2000 will bring with it a doubling of urban population in developing countries. There are challenges and opportunities to expand private sector job creation, education, clean water, and family health services. In addition to managing human settlements, there is also management of fragile ecosystems, which means relieving the pressure on these lands through urban migration or relocation to richer agricultural areas. The goal for agriculture is to triple food

  19. Balance of multi-wavelets

    Institute of Scientific and Technical Information of China (English)

    MAO Yibo

    2003-01-01

    The discrete scalar data need prefiltering when transformed by discrete multi-wavelet, but prefiltering will make some properties of multi-wavelets lost. Balanced multi-wavelets can avoid prefiltering. The sufficient and necessary condition of p-order balance for multi-wavelets in time domain, the interrelation between balance order and approximation order and the sampling property of balanced multi-wavelets are investigated. The algorithms of 1-0rder and 2-0rder balancing for multi-wavelets are obtained. The two algorithms both preserve the orthogonal relation between multi-scaling function and multi-wavelets. More importantly, balancing operation doesn't increase the length of filters, which suggests that a relatively short balanced multiwavelet can be constructed from an existing unbalanced multi-wavelet as short as possible.

  20. Sun-Earth Days

    Science.gov (United States)

    Thieman, J.; Ng, C.; Lewis, E.; Cline, T.

    2010-08-01

    Sun-Earth Day is a well-coordinated series of programs, resources and events under a unique yearly theme highlighting the fundamentals of heliophysics research and missions. A menu of activities, conducted throughout the year, inspire and educate participants. Sun-Earth Day itself can vary in date, but usually is identified by a celebration on or near the spring equinox. Through the Sun-Earth Day framework we have been able to offer a series of coordinated events that promote and highlight the Sun, its connection to Earth and the other planets. Sun-Earth Day events are hosted by educators, museums, amateur astronomers and scientists and occur at schools, community groups, parks, planetaria and science centers around the globe. Sun-Earth Day raises the awareness and knowledge of formal and informal education audiences concerning space weather and heliophysics. By building on the success of Sun-Earth Day yearly celebrations, we seek to affect people of all backgrounds and ages with the wonders of heliophysics science, discovery, and exploration in ways that are both tangible and meaningful to their lives.

  1. Earth as art three

    Science.gov (United States)

    ,

    2010-01-01

    For most of us, deserts, mountains, river valleys, coastlines even dry lakebeds are relatively familiar features of the Earth's terrestrial environment. For earth scientists, they are the focus of considerable scientific research. Viewed from a unique and unconventional perspective, Earth's geographic attributes can also be a surprising source of awe-inspiring art. That unique perspective is space. The artists for the Earth as Art Three exhibit are the Landsat 5 and Landsat 7 satellites, which orbit approximately 705 kilometers (438 miles) above the Earth's surface. While studying the images these satellites beam down daily, researchers are often struck by the sheer beauty of the scenes. Such images inspire the imagination and go beyond scientific value to remind us how stunning, intricate, and simply amazing our planet's features can be. Instead of paint, the medium for these works of art is light. But Landsat satellite sensors don't see light as human eyes do; instead, they see radiant energy reflected from Earth's surface in certain wavelengths, or bands, of red, green, blue, and infrared light. When these different bands are combined into a single image, remarkable patterns, colors, and shapes emerge. The Earth as Art Three exhibit provides fresh and inspiring glimpses of different parts of our planet's complex surface. The images in this collection were chosen solely based on their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation only for your viewing pleasure. Enjoy!

  2. 原状饱和黏土静止土压力系数试验研究%EXPERIMENTAL STUDIES OF STATIC EARTH PRESSURE COEFFICIENT OF UNDISTURBED SATURATED CLAY

    Institute of Scientific and Technical Information of China (English)

    黄博; 胡俊清; 廖先斌; 黄雄

    2013-01-01

    A number of K0-consolidation tests are carried out on the undisturbed mud/silt clay and silty clay samples of Hong Kong-Zhuhai-Macao bridge by using advanced triaxial apparatus. The changes of static soil pressure coefficient K0 under different loading and unloading paths are studied;and the applicability of using common formula and recommended value of specifications to estimate the K0 are analyzed,as well as the prediction equation based on test results is given. The results show that:K0 of mud/silt clay at the bottom of the Hong Kong-Zhuhai-Macao bridge immersed tunnel is a basically constant value(0.47). K0 of silty clay is proportional to the preconsolidation pressure and K0 is between 0.30 and 0.45;both of the bounds are lower than the recommended values of specifications and manuals for similar soil. In addition to soil properties,the cementation of the undisturbed samples also could make the K0 reduce. K0 of the strong structural undisturbed soil would decrease to below the values of normally consolidated clay and then rebound and gradually stabilize during loading stages. We can use the empirical formula given by the predecessors to estimate the K0 of normally consolidated and over-consolidated undisturbed clays;and the internal friction angle should be the effective peak internal friction angle of normally consolidated soil.%利用先进三轴仪进行港珠澳大桥岛隧工程原状土K0固结试验,研究不同加、卸载路径下土体静止土压力系数K0变化,分析常用经验公式及规范推荐值所估计静止土压力系数的适用性,并给出基于本次试验结果的预测公式。结果表明:港珠澳沉管隧道底面处的黏土层 K0基本为一定值,为0.47;粉质黏土层 K0与其先期固结压力成正比,在0.30~0.45范围内,均低于规范和手册对同类土的推荐值;除土性自身的原因外,原状样的胶结作用也会使其K0降低。结构性较强的原状土,在

  3. Laser techniques in high-pressure geophysics

    Science.gov (United States)

    Hemley, R. J.; Bell, P. M.; Mao, H. K.

    1987-01-01

    Laser techniques in conjunction with the diamond-anvil cell can be used to study high-pressure properties of materials important to a wide range of problems in earth and planetary science. Spontaneous Raman scattering of crystalline and amorphous solids at high pressure demonstrates that dramatic changes in structure and bonding occur on compression. High-pressure Brillouin scattering is sensitive to the pressure variations of single-crystal elastic moduli and acoustic velocities. Laser heating techniques with the diamond-anvil cell can be used to study phase transitions, including melting, under deep-earth conditions. Finally, laser-induced ruby fluorescence has been essential for the development of techniques for generating the maximum pressures now possible with the diamond-anvil cell, and currently provides a calibrated in situ measure of pressure well above 100 gigapascals.

  4. Negative leave balances

    CERN Document Server

    Human Resources Department

    2005-01-01

    Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1Â September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply. Â Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30Â September and/or 31Â December, leave will automatically be transferred from one account to another on the relevant dates i...

  5. Negative leave balances

    CERN Document Server

    Human Resources Department

    2005-01-01

    Members of the personnel entitled to annual leave and, where appropriate, saved leave and/or compensatory leave are requested to take note of the new arrangements described below, which were recommended by the Standing Concertation Committee (SCC) at its meeting on 1 September 2005 and subsequently approved by the Director-General. The changes do not apply to members of the personnel participating in the Progressive Retirement Programme (PRP) or the Part-time Work as a pre-retirement measure, for whom the specific provisions communicated at the time of joining will continue to apply.  Negative balances in annual leave, saved leave and/or compensatory leave accounts at the end of the leave year (30th September) and on the date on which bonuses are credited to the saved leave account (31st December): Where members of the personnel have a leave account with a negative balance on 30 September and/or 31 December, leave will automatically be transferred from one account to another on the relevant dates in or...

  6. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1996 balance year

    Science.gov (United States)

    Krimmel, Robert M.

    1997-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1996 balance year. The 1996 winter balance, averaged over the glacier, was 2.94 meters, and the net balance was 0.10meter. The winter balance was approximately 0.6 meter greater than the 1977-95 average winter balance (2.30 meters). The net balance, which was positive for the first time since 1984, was more than a meter greater than the 1977-95 average net balance (-0.96 meter). The glacier retreated about 15 meters from its 1995 position. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, and barometric pressure were measured nearby. This report makes these data available to the glaciological and climatological community

  7. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1994 balance year

    Science.gov (United States)

    Krimmel, R.M.

    1995-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1994 balance year. The 1994 winter balance, averaged over the glacier, was 2.39 meters, and the net balance was -1.60 meters. The winter balance was approximately that of the 1977-94 average winter balance. The net balance was more negative than the 1977-94 average net balance of -1.02 meters. Runoff was measured from the glacier and an adjacent non- glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured nearby. This report makes these data available to the glaciological and climatological community.

  8. Water, ice, and meteorological measurements at South Cascade Glacier, Washington, 1995 balance year

    Science.gov (United States)

    Krimmel, R.M.

    1996-01-01

    Winter snow accumulation and summer snow, firn, and ice melt were measured at South Cascade Glacier, Washington to determine the winter and net balances for the 1995 balance year. The 1995 winter balance, averaged over the glacier, was 2.86 meters, and the net balance was -0.69 meter. The winter balance was approximately 0.5 meter greater than the 1977-94 average winter balance. The net balance was approximately 0.3 meter less negative than the 1977-94 average net balance. Runoff was measured from the glacier and an adjacent non-glacierized basin. Air temperature, precipitation, barometric pressure, solar radiation, and wind speed were measured adjacent to the glacier. This report makes these data available to the glaciological and climatological community.

  9. Global ENA Imaging of Earth's Dynamic Magnetosphere

    Science.gov (United States)

    Brandt, Pontus

    2015-04-01

    The interaction between singly charged ions of Earth's magnetosphere and its neutral exosphere and upper atmosphere gives rise to Energetic Neutral Atoms (ENAs). This has enabled several missions to remotely image the global injection dynamics of the ring current and plasma sheet, the outflow of ions from Earth's polar regions, and the location of the sub-solar magnetopause. In this presentation we review ENA observations by the Astrid, IMAGE, TWINS and IBEX missions. We focus on results from the IMAGE/HENA Camera including observations of proton and oxygen ion injections in to the ring current and their impact on the force-balance and ionospheric coupling in the inner magnetosphere. We report also on the status of inversion techniques for retrieving the ion spatial and pitch-angle distributions from ENA images. The presentation concludes with a discussion of future next steps in ENA instrumentation and analysis capabilities required to deliver the science as recommended by the Heliophysics Decadal Survey.

  10. Future Satellite Gravimetry and Earth Dynamics

    CERN Document Server

    Flury, Jakob

    2005-01-01

    Currently, a first generation of dedicated satellite missions for the precise mapping of the Earth’s gravity field is in orbit (CHAMP, GRACE, and soon GOCE). The gravity data from these satellite missions provide us with very new information on the dynamics of planet Earth. In particular, on the mass distribution in the Earth’s interior, the entire water cycle (ocean circulation, ice mass balance, continental water masses, and atmosphere), and on changes in the mass distribution. The results are fascinating, but still rough with respect to spatial and temporal resolution. Technical progress in satellite-to-satellite tracking and in gravity gradiometry will allow more detailed results in the future. In this special issue, Earth scientists develop visions of future applications based on follow-on high-precision satellite gravimetry missions.

  11. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions.

    Science.gov (United States)

    Jung, HoHyun; Chun, Keyoung Jin; Hong, Jaesoo; Lim, Dohyung

    2015-01-01

    Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m(2)) were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior-posterior, right-diagonal, medial-lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P0.05). These results indicate that optimizing rotation control of the base plate of balance rehabilitation training equipment to induce anterior-posterior and medial-lateral dynamic rotation preferentially can lead to effective balance training. Additional tests with varied speeds and ranges of angles of base plate rotation are expected to be useful as well as an analysis of the balance characteristics considering a balance index that reflects the muscle activity and cooperative characteristics.

  12. Peer Pressure

    Science.gov (United States)

    ... who are unsure of themselves, new to the group, or inexperienced with peer pressure may also be more likely to give in. ... stand that makes you look uncool to your group. But these situations can be ... up to peer pressure, but it does take courage — yours: Listen to ...

  13. Whole-Earth Decompression Dynamics

    OpenAIRE

    Herndon, J. Marvin

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The i...

  14. Gambling with the earth

    CERN Multimedia

    Muir, H

    2000-01-01

    The probability that dangerous Earth-devouring particles will be born at a new accelerator in the US may be tiny, but scientists have played down the devastating potential costs in their risk assessments according to a physicist (1 page).

  15. Near Earth Objects

    DEFF Research Database (Denmark)

    Wolff, Stefan

    2006-01-01

    The word planet comes from Greek planetes, wanderers, because the planets appear to wander across the celestial sphere, contrary to the fixed stars. This thesis presents several methods for using this motion to distinguish between stars and solar system objects in order to detect and track NEOs......, Near Earth Objects: Asteroids and comets following paths that bring them near the Earth. NEOs have collided with the Earth since its formation, some causing local devastation, some causing global climate changes, yet the threat from a collision with a near Earth object has only recently been recognised...... and accepted. The European Space Agency mission Gaia is a proposed space observatory, designed to perform a highly accurate census of our galaxy, the Milky Way, and beyond. Through accurate measurement of star positions, Gaia is expected to discover thousands of extra-solar planets and follow the bending...

  16. Managing Planet Earth.

    Science.gov (United States)

    Clark, William C.

    1989-01-01

    Discusses the human use of the planet earth. Describes the global patterns and the regional aspects of change. Four requirements for the cultivation of leadership and institutional competence are suggested. Lists five references for further reading. (YP)

  17. Earth science: Extraordinary world

    Science.gov (United States)

    Day, James M. D.

    2016-09-01

    The isotopic compositions of objects that formed early in the evolution of the Solar System have been found to be similar to Earth's composition -- overturning notions of our planet's chemical distinctiveness. See Letters p.394 & p.399

  18. Analyzing earth's surface data

    Science.gov (United States)

    Barr, D. J.; Elifrits, C. D.

    1979-01-01

    Manual discusses simple inexpensive image analysis technique used to interpret photographs and scanner of data of Earth's surface. Manual is designed for those who have no need for sophisticated computer-automated analysis procedures.

  19. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    @@ July 20~31 Rare earth market still went downward, which was mainly led by sluggish demand for didymium products. Weak demand by domestic NdFeB market was attributed to continuous price falling of didymium mischmetal.

  20. Astronomy: Earth's seven sisters

    Science.gov (United States)

    Snellen, Ignas A. G.

    2017-02-01

    Seven small planets whose surfaces could harbour liquid water have been spotted around a nearby dwarf star. If such a configuration is common in planetary systems, our Galaxy could be teeming with Earth-like planets. See Letter p.456

  1. Earth rotation and geodynamics

    Science.gov (United States)

    Bogusz, Janusz; Brzezinski, Aleksander; Kosek, Wieslaw; Nastula, Jolanta

    2015-12-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals with monitoring of geodynamic phenomena. It contains analysis of geodynamic networks of local, and regional scale using space (GNSS and SLR) techniques, Earth tides monitoring with gravimeters and water-tube hydrostatic clinometer, and the determination of secular variation of the Earth' magnetic field.

  2. 脑梗死患者步行中身体质心和压力中心轨迹空间系的动态平衡研究%A study on dynamic balance of the spatial relationship between centre of mass and centre of pressure trajectories in patients with cerebral infarction during ground-walking

    Institute of Scientific and Technical Information of China (English)

    毛玉瑢; 李乐; 肖湘; 赵江莉; 黄东锋

    2012-01-01

    目的:通过对脑梗死患者平地步行中全身三维运动生物力学中身体质心(COM)和压力中心(COP)空间轨迹的分析,探讨脑梗死偏瘫患者动态平衡特点,为脑梗死患者步态康复和步行安全等提供指导.方法:选择首次脑梗死后可以独立步行10m以上的单侧偏瘫患者16例作为实验组,相匹配的正常中老年人20例为对照组.采用Vicon Nexus和AMT OR6-7进行平地步行时全身三维运动学和动力学检测和处理,用C-Motion Visual 3D分析软件进行COM和COP分析.结果:实验组和对照组比较,脑梗死患者在水平面内外侧(ML)COP-COM差值与健康老年人比较差异有显著性意义(P<0.05),其侧向摆动幅度明显增加.矢状面上足触地和离地时前后(AP)COP-COM差值与健康老年人比较差异也有显著性意义(P<0.05),但其前后偏离幅度减小.脑梗死患者健侧和患侧COP-COM比较差异无显著性(P>0.05).结论:①全身体表定位的三维运动生物力学检测可以为脑梗死患者提供动态量化平衡评估;②脑梗死患者平地步行中ML方向身体质心偏离压力中心距离大于正常中老年人,其侧向平衡较正常中老年人差.%Objective: To analyze the spatial relationship between centre of mass(COM) and centre of pressure(COP) trajectories in whole body three-dimensional biomechanics of patients with cerebral infarction during ground walking and to explore the characteristics of dynamic balance with hemiplegic gait to guide the safety walking and decreasing the risk factors of falling. Method: Sixteen patients after first cerebral infarction with unilateral hemiplegia were recruited. These patients were accorded with the criteria that the subjects can walk 10m independently. Twenty healthy elder matched subjects were selected as control group. Vicon system with force plate form was used in accordance with Plug In Gait Full Body software, COM and COP were analysed with C-Motion Visual 3D software

  3. Earth rotation and geodynamics

    OpenAIRE

    Bogusz Janusz; Brzezinski Aleksander; Kosek Wieslaw; Nastula Jolanta

    2015-01-01

    This paper presents the summary of research activities carried out in Poland in 2011-2014 in the field of Earth rotation and geodynamics by several Polish research institutions. It contains a summary of works on Earth rotation, including evaluation and prediction of its parameters and analysis of the related excitation data as well as research on associated geodynamic phenomena such as geocentre motion, global sea level change and hydrological processes. The second part of the paper deals wit...

  4. Earth/Lands

    OpenAIRE

    2011-01-01

    Earth is an essentially original and misunderstood raw material with great potential, from the positive environmental and energy ratio, to its admirable capacity to integrate other materials such as stone, wood, brick, lime, vegetable fibres, etc., capable also of constituting the sole material for whole buildings in climactical and geographically extreme situations. Earth offers a great capacity to respond to the housing needs of millions of human beings, not only quantitative needs compa...

  5. Walking the HMO balance.

    Science.gov (United States)

    Gallagher, S M

    2001-03-01

    Fidelity is the ethical obligation to act in good faith to keep promises, fulfill agreements, and maintain relationships and fiduciary responsibilities. Consumers are increasingly interested in the balance between the fiscal viability of our current healthcare delivery system and the system's reason for existence--that is, to serve the health needs of clients. Escalating healthcare costs have driven many institutions and third party payors to examine service and payment practices. Some consumers and consumer rights groups contend that these evolving practices threaten the very essence of health and healthcare. The ethical obligation of fidelity, especially as it relates to the business model of healthcare, is examined. Threats to fidelity are reviewed, and the response to these threats by one consumer rights group is presented. A case study is included.

  6. Balancing Trust and Control

    DEFF Research Database (Denmark)

    Jagd, Søren

    2010-01-01

    The purpose of this paper is to show that conceptualizing trust and control as interactively related processes, as opposed to more static conceptualizations of the two concepts and the relations between them, adds importantly towards understanding the challenges involved in balancing of trust...... and control in organizations. The paper examines recent literature on the conceptualization of the relation between trust and control in and between organizations. The literature review shows that trust and control has been conceptualized as either substituting or complementing each other. Further......, it is found that the complementary/substitution debate calls for an explicit conceptualization of the relation between trust and control as an interactive process, in contrast to earlier conceptualizations of trust and control as two relatively static and isolated concepts. While the static perspective...

  7. Balance Toward Language Mastery

    Directory of Open Access Journals (Sweden)

    Virginia R. Heslinga

    2017-01-01

    Full Text Available Problems in attaining language mastery with students from diverse language backgrounds and levels of ability confront educators around the world. Experiments, research, and experience see positive effects of adding sign language in communication methods to pre-school and K-12 education. Augmentative, alternative, interactive, accommodating, and enriching strategies using sign language aid learners in balancing the skills needed to mastery of one language or multiple languages. Theories of learning that embrace play, drama, motion, repetition, socializing, and self-efficacy connect to the options for using sign language with learners in inclusive and mainstream classes. The methodical use of sign language by this researcher-educator over two and a half decades showed signing does build thinking skills, add enjoyment, stimulate communication, expand comprehension, increase vocabulary acquisition, encourage collaboration, and helps build appreciation for cultural diversity.

  8. Quasirandom Load Balancing

    CERN Document Server

    Friedrich, Tobias; Sauerwald, Thomas

    2010-01-01

    We propose a simple distributed algorithm for balancing indivisible tokens on graphs. The algorithm is completely deterministic, though it tries to imitate (and enhance) a random algorithm by keeping the accumulated rounding errors as small as possible. Our new algorithm surprisingly closely approximates the idealized process (where the tokens are divisible) on important network topologies. On d-dimensional torus graphs with n nodes it deviates from the idealized process only by an additive constant. In contrast to that, the randomized rounding approach of Friedrich and Sauerwald (2009) can deviate up to Omega(polylog(n)) and the deterministic algorithm of Rabani, Sinclair and Wanka (1998) has a deviation of Omega(n^{1/d}). This makes our quasirandom algorithm the first known algorithm for this setting which is optimal both in time and achieved smoothness. We further show that also on the hypercube our algorithm has a smaller deviation from the idealized process than the previous algorithms.

  9. A Balancing Act?

    DEFF Research Database (Denmark)

    Gerstlberger, Wolfgang; Stampe, Ian; Knudsen, Mette Præst

    the 2009 European Manufacturing Survey for the Danish sub-sample including 335 manufacturing firms. Through factor analysis, the paper confirms three main focus areas of new product development in relation to production facilities: efficiency considerations, market attention and greening of innovation....... Logistic regression analysis demonstrates that while market attention is important for new product development, green aspects of innovation and efficiency considerations for innovation are important for the energy efficiency of the production companies. Combining these models highlights that energy...... efficiency moderates the effect of market attention on new product development. The paper therefore concludes that product innovation and energy efficiency is a balancing act, focusing on one will have detrimental effects on the other! These findings point to the conclusion that researchers and practitioners...

  10. A volume-balance model for flow on porous media

    Science.gov (United States)

    Malaga, Carlos; Mandujano, Francisco; Becerra, Julian

    2015-11-01

    Volume-balance models are used by petroleum engineers for simulating multiphase and multicomponent flow phenomena in porous media and the extraction process in oil reservoirs. In these models, mass conservation equations and Darcy's law are supplemented by a balance condition for the pore and fluid volumes. This provides a pressure equation suitable for simulating a compressible flow within a compressible solid matrix. Here we present an alternative interpretation of the volume-balance condition that includes the advective transport within a consolidated porous media. We obtain a modified equation for the time evolution of the pressure field. Numerical tests for phase separation under gravity are presented for multiphase three dimensional flow in heterogeneous porous media. The authors acknowledge funding from Fondo Sectorial CONACYT-SENER grant number 42536 (DGAJ-SPI-34-170412-217).

  11. Toward other Earths

    Science.gov (United States)

    Hatzes, Artie P.

    2016-04-01

    How common are habitable Earth-like planets? This is a key question that drives much of current research in exoplanets. To date, we have discovered over one thousand exoplanets, mostly through the transit method. Among these are Earth-size planets, but these orbit very close to the star (semi-major axis approximately 0.01 Astronomical Units). Potentially rocky planets have also been discovered in a star's habitable zone, but these have approximately twice the radius of the Earth. These certainly do not qualify as Earth "twins". Several hundreds of multi-planet systems have also been discovered, but these are mostly ultra-compact systems with up to seven planets all with orbital distances less than that of Mercury in our solar system. The detection of a planetary system that is the direct analog of our solar system still eludes us. After an overview of the current status of exoplanet discoveries I will discuss the prospects and challenges of finding such Earth analogs from the ground and from future space missions like PLATO. After over two decades of searching, we may well be on the brink of finding other Earths.

  12. The Solubility of Rock in Steam Atmospheres of the Early Earth and Hot Rocky Exoplanets

    Science.gov (United States)

    Fegley, Bruce

    2016-07-01

    Extensive experimental studies show all major rock-forming elements (e.g., Si, Mg, Fe, Ca, Al, Na, K) dissolve in steam to a greater or lesser extent. We use these results to compute chemical equilibrium abundances of rocky element - bearing gases in steam atmospheres equilibrated with silicate magma oceans. Rocky elements partition into steam atmospheres as volatile hydroxide gases (e.g., Si(OH)4, Mg(OH)2, Fe(OH)2, Ni(OH)2, Al(OH)3, Ca(OH)2, NaOH, KOH) and via reaction with HF and HCl as volatile halide gases (e.g., NaCl, KCl, CaFOH, CaClOH, FAl(OH)2) in much larger amounts than expected from their vapor pressures over volatile-free solid or molten rock at high temperatures expected for steam atmospheres on the early Earth and hot rocky exoplanets. We quantitatively compute the extent of fractional vaporization by defining gas/magma distribution coefficients and show Earth's sub-solar Si/Mg ratio may be due to loss of a primordial steam atmosphere. We conclude hot rocky exoplanets that are undergoing or have undergone escape of steam-bearing atmospheres may experience fractional vaporization and loss of Si, Mg, Fe, Ni, Al, Ca, Na, and K. This loss can modify their bulk composition, density, heat balance, and interior structure. This work was supported by NSF Astronomy Program Grant AST-1412175.

  13. Diversity of burial rates in convergent settings decreased as Earth aged.

    Science.gov (United States)

    Nicoli, Gautier; Moyen, Jean-François; Stevens, Gary

    2016-05-24

    The evolution and the growth of the continental crust is inextricably linked to the evolution of Earth's geodynamic processes. The detrital zircon record within the continental crust, as well as the isotopic composition of this crust, indicates that the amount of juvenile felsic material decreased with time and that in geologically recent times, the generation of new crust is balanced by recycling of the crust back into the mantle within subduction zones. However it cannot always have been so; yet the nature of the crust and the processes of crustal reworking in the Precambrian Earth are not well constrained. Here we use both detrital zircon ages and metamorphic pressure-temperature-time (P-T-t) information from metasedimentary units deposited in proposed convergent settings from Archaean, Proterozoic and Phanerozoic terrains to characterize the evolution of minimum estimates of burial rate (km.Ma(-1)) as a function of the age of the rocks. The demonstrated decrease in burial rate correlates positively with a progressive decrease in the production of juvenile felsic crust in the Archaean and Proterozoic. Burial rates are also more diverse in the Archaean than in modern times. We interpret these features to reflect a progressive decrease in the diversity of tectonic processes from Archaean to present, coupled with the emergence of the uniquely Phanerozoic modern-style collision.

  14. Energy balance in peridynamics.

    Energy Technology Data Exchange (ETDEWEB)

    Lehoucq, Richard B.; Silling, Stewart Andrew

    2010-09-01

    The peridynamic model of solid mechanics treats internal forces within a continuum through interactions across finite distances. These forces are determined through a constitutive model that, in the case of an elastic material, permits the strain energy density at a point to depend on the collective deformation of all the material within some finite distance of it. The forces between points are evaluated from the Frechet derivative of this strain energy density with respect to the deformation map. The resulting equation of motion is an integro-differential equation written in terms of these interparticle forces, rather than the traditional stress tensor field. Recent work on peridynamics has elucidated the energy balance in the presence of these long-range forces. We have derived the appropriate analogue of stress power, called absorbed power, that leads to a satisfactory definition of internal energy. This internal energy is additive, allowing us to meaningfully define an internal energy density field in the body. An expression for the local first law of thermodynamics within peridynamics combines this mechanical component, the absorbed power, with heat transport. The global statement of the energy balance over a subregion can be expressed in a form in which the mechanical and thermal terms contain only interactions between the interior of the subregion and the exterior, in a form anticipated by Noll in 1955. The local form of this first law within peridynamics, coupled with the second law as expressed in the Clausius-Duhem inequality, is amenable to the Coleman-Noll procedure for deriving restrictions on the constitutive model for thermomechanical response. Using an idea suggested by Fried in the context of systems of discrete particles, this procedure leads to a dissipation inequality for peridynamics that has a surprising form. It also leads to a thermodynamically consistent way to treat damage within the theory, shedding light on how damage, including the

  15. Greenland ice sheet mass balance: a review

    DEFF Research Database (Denmark)

    Khan, Shfaqat Abbas; Aschwanden, Andy; Bjørk, Anders A.

    2015-01-01

    Over the past quarter of a century the Arctic has warmed more than any other region on Earth, causing a profound impact on the Greenland ice sheet (GrIS) and its contribution to the rise in global sea level. The loss of ice can be partitioned into processes related to surface mass balance...... and to ice discharge, which are forced by internal or external (atmospheric/oceanic/basal) fluctuations. Regardless of the measurement method, observations over the last two decades show an increase in ice loss rate, associated with speeding up of glaciers and enhanced melting. However, both ice discharge...... and melt-induced mass losses exhibit rapid short-term fluctuations that, when extrapolated into the future, could yield erroneous long-term trends. In this paper we review the GrIS mass loss over more than a century by combining satellite altimetry, airborne altimetry, interferometry, aerial photographs...

  16. Approaching a realistic force balance in geodynamo simulations

    CERN Document Server

    Yadav, Rakesh K; Christensen, Ulrich R; Wolk, Scott J; Poppenhaeger, Katja

    2016-01-01

    Earth sustains its magnetic field by a dynamo process driven by convection in the liquid outer core. Geodynamo simulations have been successful in reproducing many observed properties of the geomagnetic field. However, while theoretical considerations suggest that flow in the core is governed by a balance between Lorentz force, rotational force and buoyancy (called MAC balance for Magnetic, Archimedean, Coriolis) with only minute roles for viscous and inertial forces, dynamo simulations must employ viscosity values that are many orders of magnitude larger than in the core due to computational constraints. In typical geodynamo models viscous and inertial forces are not much smaller than the Coriolis force and the Lorentz force plays a sub-dominant role. This has led to conclusions that these simulations are viscously controlled and do not represent the physics of the geodynamo. Here we show by a direct analysis of the relevant forces that a MAC balance can be achieved when the viscosity is reduced to values cl...

  17. Field reversing magnetotail current sheets: earth, Venus, and Comet Giacobini-Zinner

    Energy Technology Data Exchange (ETDEWEB)

    McComas, D.J.

    1986-09-01

    This dissertation examines the field reversing magnetotail current sheets at the earth, Venus, and Comet Giacobini-Zinner. In the near earth study a new analysis technique is developed to calculate the detailed current density distributions within the cross tail current sheet for the first time. This technique removes the effects of a variable sheet velocity by inverting intersatellite timings between the co-orbiting satellites ISEE-1 and -2. Case studies of three relatively geomagnetically quiet crossings are made; sheet thicknesses and peak current densities are approx.1-5 x 10/sup 4/ km and approx.5-50 nA/m/sup 2/. Current density distributions reveal a high density central region, lower density shoulders, and considerable fine structure throughout. In the Venus study another new analysis technique is developed to reconstruct the average tail configuration from a correlation between field magnitude and draping angle in a large statistical data set. In the comet study, high resolution magnetic field and plasma electron data from the ICE traversal of Giacobini-Zinner are combined for the first time to determine the tail/current sheet geometry and calculate certain important but unmeasured local ion and upstream properties. Pressure balance across the tail gives ion temperatures and betas of approx.1.2 x 10/sup 5/ K and approx.40 in the center of the current sheet to approx.1 x 10/sup 6/ K and approx.3 in the outer lobes. Axial stress balance shows that the velocity shear upstream near the nucleus is >6 (approx.1 at ICE), and that a region of strongly enhanced mass loading (ion source rate approx.24 times that upstream from lobes) exists upstream from the current sheet. The integrated downtail mass flux is approx.2.6 x 10/sup 26/ H/sub 2/O+/sec, which is only approx.1% of the independently determined total cometary efflux. 79 refs., 37 figs.

  18. Radar channel balancing with commutation

    Energy Technology Data Exchange (ETDEWEB)

    Doerry, Armin Walter

    2014-02-01

    When multiple channels are employed in a pulse-Doppler radar, achieving and maintaining balance between the channels is problematic. In some circumstances the channels may be commutated to achieve adequate balance. Commutation is the switching, trading, toggling, or multiplexing of the channels between signal paths. Commutation allows modulating the imbalance energy away from the balanced energy in Doppler, where it can be mitigated with filtering.

  19. When Do States Balance Power?

    DEFF Research Database (Denmark)

    Hariri, Jacob Gerner; Wivel, Anders

    2010-01-01

    This paper explores the logic of balancing in structural realist theory. Arguably, the durability of the unipolar moment is a challenge to the logic of balancing. The paper uses the tools of microeconomics to build a mathematical model of structural realism. The simple model reiterates...... the structural realist prediction that the weaker states should balance the unipole. Under a slight model extension, it is shown that efforts to balance in separate capabilities always tends to offset each other. Under this extension, the durability of the unipolar moment is in fact consistent...

  20. Analysis of human standing balance by largest lyapunov exponent.

    Science.gov (United States)

    Liu, Kun; Wang, Hongrui; Xiao, Jinzhuang; Taha, Zahari

    2015-01-01

    The purpose of this research is to analyse the relationship between nonlinear dynamic character and individuals' standing balance by the largest Lyapunov exponent, which is regarded as a metric for assessing standing balance. According to previous study, the largest Lyapunov exponent from centre of pressure time series could not well quantify the human balance ability. In this research, two improvements were made. Firstly, an external stimulus was applied to feet in the form of continuous horizontal sinusoidal motion by a moving platform. Secondly, a multiaccelerometer subsystem was adopted. Twenty healthy volunteers participated in this experiment. A new metric, coordinated largest Lyapunov exponent was proposed, which reflected the relationship of body segments by integrating multidimensional largest Lyapunov exponent values. By using this metric in actual standing performance under sinusoidal stimulus, an obvious relationship between the new metric and the actual balance ability was found in the majority of the subjects. These results show that the sinusoidal stimulus can make human balance characteristics more obvious, which is beneficial to assess balance, and balance is determined by the ability of coordinating all body segments.

  1. Improving Balance Function Using Low Levels of Electrical Stimulation of the Balance Organs

    Science.gov (United States)

    Bloomberg, Jacob; Reschke, Millard; Mulavara, Ajitkumar; Wood, Scott; Serrador, Jorge; Fiedler, Matthew; Kofman, Igor; Peters, Brian T.; Cohen, Helen

    2012-01-01

    Crewmembers returning from long-duration space flight face significant challenges due to the microgravity-induced inappropriate adaptations in balance/sensorimotor function. The Neuroscience Laboratory at JSC is developing a method based on stochastic resonance to enhance the brain's ability to detect signals from the balance organs of the inner ear and use them for rapid improvement in balance skill, especially when combined with balance training exercises. This method involves a stimulus delivery system that is wearable/portable and provides imperceptible electrical stimulation to the balance organs of the human body. Stochastic resonance (SR) is a phenomenon whereby the response of a nonlinear system to a weak periodic input signal is optimized by the presence of a particular non-zero level of noise. This phenomenon of SR is based on the concept of maximizing the flow of information through a system by a non-zero level of noise. Application of imperceptible SR noise coupled with sensory input in humans has been shown to improve motor, cardiovascular, visual, hearing, and balance functions. SR increases contrast sensitivity and luminance detection; lowers the absolute threshold for tone detection in normal hearing individuals; improves homeostatic function in the human blood pressure regulatory system; improves noise-enhanced muscle spindle function; and improves detection of weak tactile stimuli using mechanical or electrical stimulation. SR noise has been shown to improve postural control when applied as mechanical noise to the soles of the feet, or when applied as electrical noise at the knee and to the back muscles. SR using imperceptible stochastic electrical stimulation of the vestibular system (stochastic vestibular stimulation, SVS) applied to normal subjects has shown to improve the degree of association between the weak input periodic signals introduced via venous blood pressure receptors and the heart-rate responses. Also, application of SVS over 24

  2. Energy balance comparison of sorghum and sunflower

    Science.gov (United States)

    Rachidi, F.; Kirkham, M. B.; Kanemasu, E. T.; Stone, L. R.

    1993-03-01

    An understanding of the energy exchange processes at the surface of the earth is necessary for studies of global climate change. If the climate becomes drier, as is predicted for northern mid-latitudes, it is important to know how major agricultural crops will play a role in the budget of heat and moisture. Thus, the energy balance components of sorghum [ Sorghum bicolor (L.) Moench.] and sunflower ( Helianthus annuus L.), two drought-resistant crops grown in the areas where summertime drying is forecasted, were compared. Soil water content and evapotranspiration ( ET) rates also were determined. Net radiation was measured with net radiometers. Soil heat flux was analyzed with heat flux plates and thermocouples. The Bowen ratio method was used to determine sensible and latent heat fluxes. Sunflower had a higher evapotranspiration rate and depleted more water from the soil than sorghum. Soil heat flux into the soil during the daytime was greater for sorghum than sunflower, which was probably the result of the more erect leaves of sorghum. Nocturnal net radiation loss from the sorghum crop was greater than that from the sunflower crop, perhaps because more heat was stored in the soil under the sorghum crop. But daytime net radiation values were similar for the two crops. The data indicated that models of climate change must differentiate nighttime net radiation of agricultural crops. Sensible heat flux was not always less (or greater) for sorghum compared to sunflower. Sunflower had greater daytime values for latent heat flux, reflecting its greater depletion of water from the soil. Evapotranspiration rates determined by the energy balance method agreed relatively well with those found by the water balance method. For example, on 8 July (43 days after planting), the ET rates found by the energy-balance and water-balance methods were 4.6 vs. 5.5 mm/day for sunflower, respectively; for sorghum, these values were 4.0 vs. 3.5 mm/day, respectively. If the climate does

  3. Pressure Sores

    Science.gov (United States)

    ... injury. Some chronic diseases, such as diabetes and hardening of the arteries, make it hard for pressure ... Use a mild soap and warm (not hot) water. Apply moisturizers so your skin doesn’t get ...

  4. Atmospheres and evolution. [of microbial life on earth

    Science.gov (United States)

    Margulis, L.; Lovelock, J. E.

    1981-01-01

    Studies concerning the regulation of the earth atmosphere and the relation of atmospheric changes to the evolution of microbial life are reviewed. The improbable nature of the composition of the earth atmosphere in light of the atmospheric compositions of Mars and Venus and equilibrium considerations is pointed out, and evidence for the existence of microbial (procaryotic) life on earth as far back as 3.5 billion years ago is presented. The emergence of eucaryotic life in the Phanerozoic due to evolving symbioses between different procaryotic species is discussed with examples given of present-day symbiotic relationships between bacteria and eucaryotes. The idea that atmospheric gases are kept in balance mainly by the actions of bacterial cells is then considered, and it is argued that species diversity is necessary for the maintenance and origin of life on earth in its present form.

  5. Haemostatic balance in cirrhosis.

    Science.gov (United States)

    Baccouche, Héla; Labidi, Asma; Fekih, Monia; Mahjoub, Sonia; Kaabi, Houda; Hmida, Slama; Filali, Azza; Romdhane, Neila B

    2017-03-01

    Despite the prolongation of coagulation tests, recent studies reported an increased frequency of thromboembolic events in patients with cirrhosis. The aim of this study was to evaluate the haemostatic balance in cirrhotic patients through assessing the variation of pro- and anticoagulant factors and evaluating the in-vitro thrombin generation in patients with cirrhosis and in healthy patients. Fifty-one cirrhotic patients with or without thromboembolic events and 50 controls matched by age and sex were enrolled. Procoagulant (factors VII, II, V, VIII, and XII) and inhibitor (protein C, protein S and antithrombin) factor activities were determined. Thrombin generation was measured as endogenous thrombin potential (ETP). Haemostatic balance was assessed by means of both procoagulant to inhibitor coagulation factor ratios and ETP with to without protein C activation ratios. There were 24 males and 27 females. The mean age was 57.8 years [16-91 years]. Pro and anticoagulant factors were significantly lower in patients than in controls (P < 0.001) except for factor VIII and protein S. In fact factor VIII level was significantly higher in patients than in controls and protein S levels were not significantly different between patients and controls. Almost all the pro to anticoagulant factor ratios were higher in cirrhotics than in controls, especially the factor VIII to protein C ratios which increased significantly from Child Pugh A to C (P < 0.001), the ratio of ETP with to without protein C activator was higher in patients than in controls, but did not reach a significant level (0.8 vs. 0.52) There was no statistically significant difference between Child classes. When comparing patients with history of thrombosis (n = 7) to those matched by age and sex and without history of thrombosis (n = 14), the ratios were not statistically different between the two groups. Haemostatic changes in cirrhosis tend to rebalance the haemostatic system. This state often

  6. Perceived Work-Life Balance Ability, Job Satisfaction, and Professional Commitment among Agriculture Teachers

    Science.gov (United States)

    Sorensen, Tyson J.; McKim, Aaron J.

    2014-01-01

    Agriculture teachers participate in various work and life roles, which can create challenges when trying to balance the pressures and responsibilities associated with each role. When one is unable to balance and prioritize between roles, both satisfaction and professional commitment may be reduced. The purpose of this study was to describe Oregon…

  7. The earth's hydrological cycle

    CERN Document Server

    Bonnet, R-M; Calisto, M; Destouni, G; Gurney, R; Johannessen, J; Kerr, Y; Lahoz, WA; Rast, M

    2014-01-01

    This book gives a comprehensive presentation of our present understanding of the Earth's Hydrological cycle and the problems, consequences and impacts that go with this topic. Water is a central component in the Earth's system. It is indispensable for life on Earth in its present form and influences virtually every aspect of our planet's life support system. On relatively short time scales, atmospheric water vapor interacts with the atmospheric circulation and is crucial in forming the Earth's climate zones. Water vapor is the most powerful of the greenhouse gases and serves to enhance the tropospheric temperature. The dominant part of available water on Earth resides in the oceans. Parts are locked up in the land ice on Greenland and Antarctica and a smaller part is estimated to exist as groundwater. If all the ice over the land and all the glaciers were to melt, the sea level would rise by some 80 m. In comparison, the total amount of water vapor in the atmosphere is small; it amounts to ~ 25 kg/m2, or the ...

  8. Modeling the earth system

    Energy Technology Data Exchange (ETDEWEB)

    Ojima, D. [ed.

    1992-12-31

    The 1990 Global Change Institute (GCI) on Earth System Modeling is the third of a series organized by the Office for Interdisciplinary Earth Studies to look in depth at particular issues critical to developing a better understanding of the earth system. The 1990 GCI on Earth System Modeling was organized around three themes: defining critical gaps in the knowledge of the earth system, developing simplified working models, and validating comprehensive system models. This book is divided into three sections that reflect these themes. Each section begins with a set of background papers offering a brief tutorial on the subject, followed by working group reports developed during the institute. These reports summarize the joint ideas and recommendations of the participants and bring to bear the interdisciplinary perspective that imbued the institute. Since the conclusion of the 1990 Global Change Institute, research programs, nationally and internationally, have moved forward to implement a number of the recommendations made at the institute, and many of the participants have maintained collegial interactions to develop research projects addressing the needs identified during the two weeks in Snowmass.

  9. The Sun and Earth

    Science.gov (United States)

    Gopalswamy, Natchimuthuk

    2012-01-01

    Thus the Sun forms the basis for life on Earth via the black body radiation it emits. The Sun also emits mass in the form of the solar wind and the coronal mass ejections (CMEs). Mass emission also occurs in the form of solar energetic particles (SEPs), which happens during CMEs and solar flares. Both the mass and electromagnetic energy output of the Sun vary over a wide range of time scales, thus introducing disturbances on the space environment that extends from the Sun through the entire heliosphere including the magnetospheres and ionospheres of planets and moons of the solar system. Although our habitat is located in the neutral atmosphere of Earth, we are intimately connected to the non-neutral space environment starting from the ionosphere to the magnetosphere and to the vast interplanetary space. The variability of the solar mass emissions results in the interaction between the solar wind plasma and the magnetospheric plasma leading to huge disturbances in the geospace. The Sun ionizes our atmosphere and creates the ionosphere. The ionosphere can be severely disturbed by the transient energy input from solar flares and the solar wind during geomagnetic storms. The complex interplay between Earth's magnetic field and the solar magnetic field carried by the solar wind presents varying conditions that are both beneficial and hazardous to life on earth. This seminar presents some of the key aspects of this Sun-Earth connection that we have learned since the birth of space science as a scientific discipline some half a century ago.

  10. Earth Global Reference Atmospheric Model 2007 (Earth-GRAM07) Applications for the NASA Constellation Program

    Science.gov (United States)

    Leslie, Fred W.; Justus, C. G.

    2008-01-01

    Engineering models of the atmosphere are used extensively by the aerospace community for design issues related to vehicle ascent and descent. The Earth Global Reference Atmosphere Model version 2007 (Earth-GRAM07) is the latest in this series and includes a number of new features. Like previous versions, Earth-GRAM07 provides both mean values and perturbations for density, temperature, pressure, and winds, as well as monthly- and geographically-varying trace constituent concentrations. From 0 km to 27 km, thermodynamics and winds are based on the National Oceanic and Atmospheric Administration Global Upper Air Climatic Atlas (GUACA) climatology. For altitudes between 20 km and 120 km, the model uses data from the Middle Atmosphere Program (MAP). Above 120 km, EarthGRAM07 now provides users with a choice of three thermosphere models: the Marshall Engineering Thermosphere (MET-2007) model; the Jacchia-Bowman 2006 thermosphere model (JB2006); and the Naval Research Labs Mass Spectrometer, Incoherent Scatter Radar Extended Model (NRL MSIS E-OO) with the associated Harmonic Wind Model (HWM-93). In place of these datasets, Earth-GRAM07 has the option of using the new 2006 revised Range Reference Atmosphere (RRA) data, the earlier (1983) RRA data, or the user may also provide their own data as an auxiliary profile. Refinements of the perturbation model are also discussed which include wind shears more similar to those observed at the Kennedy Space Center than the previous version Earth-GRAM99.

  11. Hydrogen solubility in rare earth based hydrogen storage alloys

    Energy Technology Data Exchange (ETDEWEB)

    Uchida, Hirohisa [Tokai Univ., Kanagawa (Japan). School of Engineering; Kuji, Toshiro [Mitsui Mining and Smelting Co. Ltd., Saitama (Japan)

    1999-09-01

    This paper reviews significant results of recent studies on the hydrogen storage properties of rare earth based AB{sub 5} (A: rare earth element, B: transition element) alloys The hydrogen solubility and the hydride formation, typically appeared in pressure-composition isotherms (PCT), are strongly dependent upon alloy composition, structure, morphology and even alloy particle size. Typical experimental results are shown to describe how these factors affect the hydrogen solubility and storage properties.

  12. A balanced memory network.

    Directory of Open Access Journals (Sweden)

    Yasser Roudi

    2007-09-01

    Full Text Available A fundamental problem in neuroscience is understanding how working memory--the ability to store information at intermediate timescales, like tens of seconds--is implemented in realistic neuronal networks. The most likely candidate mechanism is the attractor network, and a great deal of effort has gone toward investigating it theoretically. Yet, despite almost a quarter century of intense work, attractor networks are not fully understood. In particular, there are still two unanswered questions. First, how is it that attractor networks exhibit irregular firing, as is observed experimentally during working memory tasks? And second, how many memories can be stored under biologically realistic conditions? Here we answer both questions by studying an attractor neural network in which inhibition and excitation balance each other. Using mean-field analysis, we derive a three-variable description of attractor networks. From this description it follows that irregular firing can exist only if the number of neurons involved in a memory is large. The same mean-field analysis also shows that the number of memories that can be stored in a network scales with the number of excitatory connections, a result that has been suggested for simple models but never shown for realistic ones. Both of these predictions are verified using simulations with large networks of spiking neurons.

  13. Paul Collier : Balancing beams

    CERN Multimedia

    2009-01-01

    As former head of AB Operations, Paul Collier and his group were in the ‘cockpit’ for the LHC’s maiden voyage - piloting the first beam around the ring. But now, as Head of the Beams Department, he will need his feet firmly on the ground in order to balance all the beam activities at CERN. "As Department Head, I’ll have less direct contact with the machines," Collier says with a hint of regret. "I’ll still obviously be very involved, but they won’t actually let me loose in front of the keyboard anymore!" As the new Head of the BE Department, Collier will be in charge of nearly 400 people, and will oversee all the beam activities, including the preparations for the longest period of beam operation in the history of CERN. In the new organization, the BE, TE and EN Departments have been grouped together in the Accelerator and Technology Sector. "‘Partnership’ is a key word for the three departments," says Collier. "The n...

  14. The right balance

    CERN Multimedia

    CERN Bulletin

    2010-01-01

    Over the course of her career as a physicist, Felicitas Pauss, currently responsible for CERN's External Relations, has often been the sole woman in an environment dominated by men. While she freely admits that being a woman physicist can have as many advantages as disadvantages, she thinks the best strategy is to maintain the right balance.   From a very early age, Felicitas Pauss always wanted to be involved in projects that interested and fascinated her. That's how she came to study physics. When she was a first-year university student in Austria in 1970, it was still fairly uncommon for women to go into physics research. "I grew up in Salzburg with a background in music. At that time, it was certainly considered more ‘normal’ for a woman to study music than to do research in physics. But already in high school I was interested in physics and technical instruments and wanted to know how things work and what they are made of”. At the beginning of her care...

  15. Better Than Earth

    CERN Document Server

    Heller, René

    2015-01-01

    Do We Inhabit The Best O All Possible Worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  16. Better Than Earth

    Science.gov (United States)

    Heller, René

    2015-01-01

    Do we inhabit the best of all possible worlds? German mathematician Gottfried Leibniz thought so, writing in 1710 that our planet, warts and all, must be the most optimal one imaginable. Leibniz's idea was roundly scorned as unscientific wishful thinking, most notably by French author Voltaire in his magnum opus, Candide. Yet Leibniz might find sympathy from at least one group of scientists - the astronomers who have for decades treated Earth as a golden standard as they search for worlds beyond our own solar system. Because earthlings still know of just one living world - our own - it makes some sense to use Earth as a template in the search for life elsewhere, such as in the most Earth-like regions of Mars or Jupiter's watery moon Europa. Now, however, discoveries of potentially habitable planets orbiting stars other than our sun - exoplanets, that is - are challenging that geocentric approach.

  17. Balancing for unstable nonlinear systems

    NARCIS (Netherlands)

    Scherpen, J.M.A.

    1993-01-01

    A previously obtained method of balancing for stable nonlinear systems is extended to unstable nonlinear systems. The similarity invariants obtained by the concept of LQG balancing for an unstable linear system can also be obtained by considering a past and future energy function of the system. By c

  18. Risk, Balanced Skills and Entrepreneurship

    DEFF Research Database (Denmark)

    Hsieh, Chihmao; Parker, Simon C.; Van Praag, Mirjam

    2017-01-01

    This paper proposes that risk aversionencourages individuals to invest in balanced skillprofiles, making them more likely to become entrepreneurs.By not taking this possible linkage intoaccount, previous research has underestimated theimpacts of both risk aversion and balanced skills onthe likeli...

  19. Risk, Balanced Skills and Entrepreneurship

    NARCIS (Netherlands)

    C. Hsieh; S.C. Parker; M.C. van Praag

    2015-01-01

    This paper proposes that risk aversion encourages individuals to invest in balanced skill profiles, making them more likely to become entrepreneurs. By not having taken this possible linkage into account, previous research has underestimated the impacts both of risk aversion and balanced skills on t

  20. Designing Multinational Electricity Balancing Markets

    NARCIS (Netherlands)

    Van der Veen, R.A.C.

    2012-01-01

    In today’s unbundled electricity markets, the balancing market is an intricate institutional arrangement that makes sure that the balance between electricity supply and demand is maintained. In the light of the development of a single electricity market in Europe, harmonization and integration of cu

  1. Geoneutrino and Hydridic Earth model

    CERN Document Server

    Bezrukov, Leonid

    2013-01-01

    Uranium, Thorium and Potassium-40 abundances in the Earth were calculated in the frame of Hydridic Earth model. Terrestrial heat producton from U, Th and K40 decays was calculated also. We must admit the existance of Earth expansion process to understand the obtained large value of terrestrial heat producton. The geoneutrino detector with volume more than 5 kT (LENA type) must be constructed to definitely separate between Bulk Silicat Earth model and Hydridic Earth model.

  2. How Big is Earth?

    Science.gov (United States)

    Thurber, Bonnie B.

    2015-08-01

    How Big is Earth celebrates the Year of Light. Using only the sunlight striking the Earth and a wooden dowel, students meet each other and then measure the circumference of the earth. Eratosthenes did it over 2,000 years ago. In Cosmos, Carl Sagan shared the process by which Eratosthenes measured the angle of the shadow cast at local noon when sunlight strikes a stick positioned perpendicular to the ground. By comparing his measurement to another made a distance away, Eratosthenes was able to calculate the circumference of the earth. How Big is Earth provides an online learning environment where students do science the same way Eratosthenes did. A notable project in which this was done was The Eratosthenes Project, conducted in 2005 as part of the World Year of Physics; in fact, we will be drawing on the teacher's guide developed by that project.How Big Is Earth? expands on the Eratosthenes project by providing an online learning environment provided by the iCollaboratory, www.icollaboratory.org, where teachers and students from Sweden, China, Nepal, Russia, Morocco, and the United States collaborate, share data, and reflect on their learning of science and astronomy. They are sharing their information and discussing their ideas/brainstorming the solutions in a discussion forum. There is an ongoing database of student measurements and another database to collect data on both teacher and student learning from surveys, discussions, and self-reflection done online.We will share our research about the kinds of learning that takes place only in global collaborations.The entrance address for the iCollaboratory is http://www.icollaboratory.org.

  3. Atmosphere-earth angular momentum exchange and ENSO cycle

    Institute of Scientific and Technical Information of China (English)

    钱维宏; 丑纪范

    1996-01-01

    The time series of the earth’s rotation rate, eastern equatorial Pacific sea surface temperature (Tss), sea level pressure (Psl) and atmospheric angular momentum (Maa) during 1976 -1989 are used to study the relation between atmosphere-earth angular momentum exchange and ENSO cycle. The result shows that (i) there are synergetic relationships among the variations of solid earth’s rotation, eastern equatorial Pacific T,, Psl, different latitude zonal Maa and global Maa; (ii) local atmosphere-ocean interaction over low-latitude area can form ENSO-like cycle through Hadley circulation; (iii) the solid earth and global atmosphere-ocean interaction can form some aperiodic behavior and asynchronous oscillations by mountain torque and earth spin anomalous friction torque acting on each component of solid earth-ocean-atmosphere system; and (iv) actual ENSO cycle is a phenomenon reflecting in Pacific basin through interaction among solid earth, global ocean and the atmosphere.

  4. Rare (Earth Elements [score

    Directory of Open Access Journals (Sweden)

    Camilo Méndez

    2014-12-01

    Full Text Available Rare (Earth Elements is a cycle of works for solo piano. The cycle was inspired by James Dillon’s Book of Elements (Vol. I-V. The complete cycle will consist of 14 pieces; one for each selected rare (earth element. The chosen elements are Neodymium, Erbium, Tellurium, Hafnium, Tantalum, Technetium, Indium, Dysprosium, Lanthanium, Cerium, Europium, Terbium, Yttrium and Darmstadtium. These elements were selected due to their special atomic properties that in many cases make them extremely valuable for the development of new technologies, and also because of their scarcity. To date, only 4 works have been completed Yttrium, Technetium, Indium and Tellurium.

  5. Teaching earth science

    Science.gov (United States)

    Alpha, Tau Rho; Diggles, M.F.

    1998-01-01

    This CD-ROM contains 17 teaching tools: 16 interactive HyperCard 'stacks' and a printable model. They are separated into the following categories: Geologic Processes, Earthquakes and Faulting, and Map Projections and Globes. A 'navigation' stack, Earth Science, is provided as a 'launching' place from which to access all of the other stacks. You can also open the HyperCard Stacks folder and launch any of the 16 stacks yourself. In addition, a 17th tool, Earth and Tectonic Globes, is provided as a printable document. Each of the tools can be copied onto a 1.4-MB floppy disk and distributed freely.

  6. Alkaline earth metal thioindates

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov-Ehmin, B.N.; Ivlieva, V.I.; Filatenko, L.A.; Zajtsev, B.E.; Kaziev, G.Z.; Sarabiya, M.G.

    1984-08-01

    Alkaline earth metal thioindates of MIn/sub 2/S/sub 4/ composition were synthesized by interaction of alkaline earth metal oxoindates with hydrogen sulfide during heating. Investigation into the compounds by X-ray analysis showed that calcium compound crystallizes in cubic crystal system and strontium and barium compounds in rhombic crystal system. Lattice parameters and the number of formula units were determined. Thioindates of M/sub 3/In/sub 2/S/sub 6/ composition were synthesized, their individuality was shown.

  7. Quantizing Earth surface deformations

    Directory of Open Access Journals (Sweden)

    C. O. Bowin

    2015-03-01

    Full Text Available The global analysis of Bowin (2010 used the global 14 absolute Euler pole set (62 Myr history from Gripp and Gordon (1990 and demonstrated that plate tectonics conserves angular momentum. We herein extend that analysis using the more detailed Bird (2003 52 present-day Euler pole set (relative to a fixed Pacific plate for the Earth's surface, after conversion to absolute Euler poles. Additionally, new analytical results now provide new details on upper mantle mass anomalies in the outer 200 km of the Earth, as well as an initial quantizing of surface deformations.

  8. Field Measurements and Pullout Tests of Reinforced Earth Retaining Wall

    Institute of Scientific and Technical Information of China (English)

    陈群; 何昌荣; 朱分清

    2004-01-01

    In this paper, field measurements and pullout tests of a new type of reinforced earth retaining wall, which is reinforced by trapezoid concrete blocks connected by steel bar, are described. Field measurements included settlements of the earth fill, tensile forces in the ties and earth pressures on the facing panels during the construction and at completion. Based on the measurements, the following statements can be made: ( 1 ) the tensile forces in the ties increased with the height of backfill above the tie and there is a tensile force crest in most ties; (2) at completion, the measured earth pressures along the wall face were between the values of the active earth pressures and the pressures at rest; (3) larger settlements occurred near the face of the wall where a zone of drainage sand and gravel was not compacted properly and smaller settlements occurred in the well-compacted backfill. The results of field pullout tests indicated that the magnitudes of pullout resistances as well as tensile forces induced in the ties were strongly influenced by the relative displacements between the ties and the backfill, and pullout resistances increased with the height of backfill above the ties and the length of ties.

  9. Seismic rehabilitation and analysis of Chaohe earth dam

    Institute of Scientific and Technical Information of China (English)

    Lei Fu; Xiangwu Zeng

    2005-01-01

    Stability of earth dams during earthquakes has been a major concern for geotechnical engineers in seismic active regions. Liquefaction induced slope failure occurred at the upstream slope of a major earth dam in the suburb of Beijing, China, during the 1976 Tangshan Earthquake. The gravelly soil with loose initial condition liquefied under relatively small ground vibration. In recent years, a major seismic rehabilitation project was carried out on a similar earth dam nearby using dumped quarry stone. Seismic stability analysis was carried out using model test, finite element simulation, and pseudostatic slope stability program after taking into account the influence of excess pore pressure.

  10. Physical Controls of the Earth's Climate and Climate change

    Science.gov (United States)

    Stephens, Graeme

    2013-03-01

    The Earth's climate system and changes to it are determined by the physical processes that govern the flows of energy to and from the atmosphere and Earth's surface. Although the energy exchanges at the top of the atmosphere are well determined from available satellite measurements, the global character of the energy flows within the climate system, and to and from the Earth's surface in particular, are not directly measured and thus are much more uncertain. The surface energy balance is particularly important since geographical variations of its distribution drives ocean circulations, dictates the amount of water evaporated from the Earth's surface, fuels the planetary hydrological cycle and ultimately controls how this hydrological cycle responds to forced climate change. This talk reviews our state of understanding of the physical processes that determine the energy balance, couple to the Earth's water cycle and are responsible for the most important climate feedbacks that dictate the pace of climate change. Challenges in understanding the mechanisms responsible for feedbacks associated with clouds and precipitation, water vapor, snow cover and carbon will be highlighted. The further complexity and uncertainty that aerosols add to the cloud and precipitation feedbacks will also be reviewed. The effects of uncertainties in our understanding of the physical climate system, and feedbacks within it, will be reviewed in the context of climate change projections.

  11. Social Balance Theory: Revisiting Heider’s Balance Theory for many agents

    OpenAIRE

    Hokky Situngkir; Deni Khanafiah

    2004-01-01

    We construct a model based on Heider’s social balance theory to analyze the interpersonal network among social agents. The model of social balance theory provides us an interesting tool to see how a social group evolves to the possible balance state. We introduce the balance index that can be used to measure social balance in macro structure level (global balance index) or in micro structure (local balance index) to see how the local balance index influences the global balance structure. Seve...

  12. Connections between the bulk composition, geodynamics and habitability of Earth

    Science.gov (United States)

    Jellinek, A. M.; Jackson, M. G.

    2015-08-01

    The bulk composition of the silicate part of Earth has long been linked to chondritic meteorites. Ordinary chondrites -- the most abundant meteorite class -- are thought to represent planetary building materials. However, a landmark discovery showed that the 142Nd/144Nd ratio of the accessible parts of the modern terrestrial mantle on Earth is greater than that of ordinary chondrites. If Earth was derived from these precursors, mass balance requires that a missing reservoir with 142Nd/144Nd lower than ordinary chondrites was isolated from the accessible mantle within 20 to 30 million years of accretion. This reservoir would host the equivalent of the modern continents' budget of radioactive heat-producing elements (uranium, thorium and potassium), yet has not been discovered. We argue that this reservoir could have been lost to space by ablation from early impactors. If so, Earth's radiogenic heat generation is between 18 and 45% lower than estimates based on a chondritic composition. Calculations of Earth's thermal history that incorporate such reduced radiogenic heating are consistent with a transition to the current plate tectonic mode in the past 2.5 billion years or so, a late onset of the dynamo and an evolving rate of volcanic outgassing consistent with Earth's long-term habitable climate. Reduced heat production compared with Venus and Mars could also explain aspects of the differences between the current climatic regimes of these planets and Earth.

  13. Experimental Probing on Formation Mechanism of Hydrocarbon in Deep Earth

    Institute of Scientific and Technical Information of China (English)

    Weng Kenan; Xiao Wansheng; Zhang Huizi; Wang Benshan

    1997-01-01

    @@ In order to study the formation mechanism of hydrocarbon in the earth's interior, preliminary experiments on chemical reactions of wax, graphite, siderite with supercritical water have been carried out respectively under the conditions of temperature about 800~1500℃ and pressure approximately above 1 GPa. These reactions can produce a large amount of methane, together with some CO2 and a little other hydrocarbons, indicating that the reactions of carbon-bearing materials with supercritical water is possibly a new formation mechanism of hydrocarbon under the conditions of high temperature and high pressure in deep earth.

  14. New ESA Earth Explorer Missions

    Science.gov (United States)

    Herland, E.

    2006-12-01

    concentrating on the UTLS region. Linking with MetOP/NPOESS data will also useful insights into processes occurring in the lower troposphere. Carries an infrared and a microwave radiometer. FLEX Fluorescence Explorer Mission: Global remote sensing of vegetation photosynthesis through measurement of fluorescence. Photosynthesis by land vegetation is an important component of the global carbon cycle, and is closely linked to the hydrological cycle through transpiration. Will measure high spectral resolution reflectance and temperature, and provide a multi-angular capability. A-SCOPE Advanced Space Carbon and Climate Observation of Planet Earth: Total column CO2 with a nadir-looking pulsed CO2 differential Absorption Lidar (DIAL) for better understanding of the global carbon cycle and regional CO2 fluxes, as well as for validation of greenhouse-gases emission inventories. CoReH2O Cold Regions Hydrology High-resolution Observatory: Spatially detailed observations of key snow, ice, and water cycle characteristics necessary for understanding land surface, atmosphere and ocean processes and interactions by using two synthetic aperture radars at 9.6 and 17.2 GHz. Aims at closing the gaps in detailed information on snow glaciers and surface water, with improving modelling and prediction of water balance and streamflow for snow covered and glacierised basins, understanding and modelling the water and energy cycles in high latitudes, assessing and forecasting water supply from snow cover and glaciers, including the assessment of effects of climate change and monitoring land surface water extent in high latitudes and its relation to climate variability.

  15. Earth System Science Education Modules

    Science.gov (United States)

    Hall, C.; Kaufman, C.; Humphreys, R. R.; Colgan, M. W.

    2009-12-01

    The College of Charleston is developing several new geoscience-based education modules for integration into the Earth System Science Education Alliance (ESSEA). These three new modules provide opportunities for science and pre-service education students to participate in inquiry-based, data-driven experiences. The three new modules will be discussed in this session. Coastal Crisis is a module that analyzes rapidly changing coastlines and uses technology - remotely sensed data and geographic information systems (GIS) to delineate, understand and monitor changes in coastal environments. The beaches near Charleston, SC are undergoing erosion and therefore are used as examples of rapidly changing coastlines. Students will use real data from NASA, NOAA and other federal agencies in the classroom to study coastal change. Through this case study, learners will acquire remotely sensed images and GIS data sets from online sources, utilize those data sets within Google Earth or other visualization programs, and understand what the data is telling them. Analyzing the data will allow learners to contemplate and make predictions on the impact associated with changing environmental conditions, within the context of a coastal setting. To Drill or Not To Drill is a multidisciplinary problem based module to increase students’ knowledge of problems associated with nonrenewable resource extraction. The controversial topic of drilling in the Arctic National Wildlife Refuge (ANWR) examines whether the economic benefit of the oil extracted from ANWR is worth the social cost of the environmental damage that such extraction may inflict. By attempting to answer this question, learners must balance the interests of preservation with the economic need for oil. The learners are exposed to the difficulties associated with a real world problem that requires trade-off between environmental trust and economic well-being. The Citizen Science module challenges students to translate scientific

  16. "Galileo Calling Earth..."

    Science.gov (United States)

    National Aeronautics and Space Administration, Washington, DC.

    This guide presents an activity for helping students understand how data from the Galileo spacecraft is sent to scientists on earth. Students are asked to learn about the concepts of bit-rate and resolution and apply them to the interpretation of images from the Galileo Orbiter. (WRM)

  17. Earth as art 4

    Science.gov (United States)

    ,

    2016-03-29

    Landsat 8 is the latest addition to the long-running series of Earth-observing satellites in the Landsat program that began in 1972. The images featured in this fourth installment of the Earth As Art collection were all acquired by Landsat 8. They show our planet’s diverse landscapes with remarkable clarity.Landsat satellites see the Earth as no human can. Not only do they acquire images from the vantage point of space, but their sensors record infrared as well as visible wavelengths of light. The resulting images often reveal “hidden” details of the Earth’s land surface, making them invaluable for scientific research.As with previous Earth As Art exhibits, these Landsat images were selected solely for their aesthetic appeal. Many of the images have been manipulated to enhance color variations or details. They are not intended for scientific interpretation—only for your viewing pleasure. What do you see in these unique glimpses of the Earth’s continents, islands, and coastlines?

  18. Olympus and Earth Day

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Let your gaze rest upon the poster for Earth Day on April 22. A small polar bear clings tightly to the stem of an aero-vane. Staring at the vanishing floating ice on the wild sea, his eyes are full of panic and fear.

  19. Cosmic rays on earth

    Energy Technology Data Exchange (ETDEWEB)

    Allkofer, O.C.; Grieder, P.K.F.

    1984-01-01

    A data collection is presented that covers cosmic rays on earth. Included are all relevant data on flux and intensity measurements, energy spectra, and related data of all primary and secondary components of the cosmic radiation at all levels in the atmosphere, at sea level and underground. In those cases where no useful experimental data have been available, theoretical predictions were substituted.

  20. Between Earth and Sky

    DEFF Research Database (Denmark)

    Carter, Adrian

    2009-01-01

    to rescue architecture from the sterile impasse of late-modernism. In his works the basic elements of lived space become present: the earth, the sky and the `between` of human existence." Jørn Utzon's architecture ranges from the modest to the monumental; from the Kingo courtyard houses, the finest...

  1. Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ Rare earth market continued drop tendency.There was not much transaction of didymium oxide and the alloy. Affected by reduced order of NdFeB magnetic materials and inactive dealings of didymium mischmetal,price of didymium mischmetal had dropped from RMB ¥95,000~98,000/ton to RMBY 93,000~95,000/ton currently.

  2. Earth flyby anomalies

    Energy Technology Data Exchange (ETDEWEB)

    Nieto, Michael Martin [Los Alamos National Laboratory; Anderson, John D [PROPULSION LAB.

    2009-01-01

    In the planet-centric system, a spacecraft should have the same initial and final energies, even though its energy and angular momentum will change in the barycenter of the solar system. However, without explanation, a number of earth flybys have yielded small energy changes.

  3. Magnetic rare earth superlattices

    DEFF Research Database (Denmark)

    Majkrzak, C.F.; Kwo, J.; Hong, M.;

    1991-01-01

    Advances in molecular beam epitaxy deposition techniques have recently made it possible to grow, an atomic plane at a time, single crystalline superlattices composed of alternating layers of a magnetic rare earth, such as Gd, Dy, Ho, or Er, and metallic Y, which has an identical chemical structure...

  4. DIORAMA Earth Terrain Model

    Energy Technology Data Exchange (ETDEWEB)

    Werley, Kenneth Alan [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-03-10

    When simulating near-surface nuclear detonations, the terrain of the Earth can have an effect on the observed outputs. The critical parameter is called the “height of burst”. In order to model the effect of terrain on the simulations we have incorporated data from multiple sources to give 9 km resolution data with global coverage.

  5. Google Earth Science

    Science.gov (United States)

    Baird, William H.; Padgett, Clifford W.; Secrest, Jeffery A.

    2015-01-01

    Google Earth has made a wealth of aerial imagery available online at no cost to users. We examine some of the potential uses of that data in illustrating basic physics and astronomy, such as finding the local magnetic declination, using landmarks such as the Washington Monument and Luxor Obelisk as gnomons, and showing how airport runways get…

  6. Bones of the Earth

    Science.gov (United States)

    Correa, Jose Miguel

    2014-01-01

    The film "Bones of the Earth" (Riglin, Cunninham & Correa, 2014) is an experience in collective inquiry and visual creation based on arts-based research. Starting from the meeting of different subjectivities and through dialogue, planning, shooting and editing, an audiovisual text that reconstructs a reflexive process of collective…

  7. Protect the Earth

    Institute of Scientific and Technical Information of China (English)

    张永兴

    2011-01-01

    The earth, a blue globe, is very beautiful. It is the home to all the living things. But the environment around us is becoming worse and worse. People cut down trees to build houses and throw about litter. The air pollution is almost everywhere in the world!

  8. Whole-Earth Decompression Dynamics

    CERN Document Server

    Herndon, J M

    2005-01-01

    The principles of Whole-Earth Decompression Dynamics are disclosed leading to a new way to interpret whole-Earth dynamics. Whole-Earth Decompression Dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continential displacement, plate tectonics theory and Earth expansion theory. Whole-Earth decompression is the consequence of Earth formation from within a Jupiter-like protoplanet with subsequent loss of gases and ices and concomitant rebounding. The initial whole-Earth decompression is expected to result in a global system of major primary decompression cracks appearing in the rigid crust which persist as the basalt feeders for the global, mid-oceanic ridge system. As the Earth subsequently decompresses, the area of the Earth's surface increases by the formation of secondary decompression cracks, often located near the continental margins, presently identified as oceanic trenches. These secondary decompression cracks are subsequently in-filled with basalt, extruded fr...

  9. Conceptual radiometer design studies for Earth observations from low Earth orbit

    Science.gov (United States)

    Harrington, Richard F.

    1994-01-01

    A conceptual radiometer design study was performed to determine the optimum design approach for spaceborne radiometers in low Earth orbit. Radiometric system configurations which included total power radiometers, unbalanced Dicke radiometers, and balanced Dicke, or as known as noise injection, radiometers were studied. Radiometer receiver configurations which were analyzed included the direct detection radiometer receiver, the double sideband homodyne radiometer receiver, and the single sideband heterodyne radiometer receiver. Radiometer system performance was also studied. This included radiometric sensitivity analysis of the three different radiometer system configurations studied. Both external and internal calibration techniques were analyzed. An accuracy analysis with and without mismatch losses was performed. It was determined that the balanced Dicke radiometer system configuration with direct detection receivers and external calibrations was optimum where frequent calibration such as once per minute were not feasible.

  10. Optimized balance rehabilitation training strategy for the elderly through an evaluation of balance characteristics in response to dynamic motions

    Directory of Open Access Journals (Sweden)

    Jung HH

    2015-10-01

    Full Text Available HoHyun Jung,1 Keyoung Jin Chun,2 Jaesoo Hong,2 Dohyung Lim1 1Department of Mechanical Engineering, Sejong University, Seoul, Republic of Korea; 2Smart Welfare Technology Research Group, Korea Institute of Industrial Technology, Cheonan, Republic of Korea Abstract: Balance is important in daily activities and essential for maintaining an independent lifestyle in the elderly. Recent studies have shown that balance rehabilitation training can improve the balance ability of the elderly, and diverse balance rehabilitation training equipment has been developed. However, there has been little research into optimized strategies for balance rehabilitation training. To provide an optimized strategy, we analyzed the balance characteristics of participants in response to the rotation of a base plate on multiple axes. Seven male adults with no musculoskeletal or nervous system-related diseases (age: 25.5±1.7 years; height: 173.9±6.4 cm; body mass: 71.3±6.5 kg; body mass index: 23.6±2.4 kg/m2 were selected to investigate the balance rehabilitation training using customized rehabilitation equipment. Rotation of the base plate of the equipment was controlled to induce dynamic rotation of participants in the anterior–posterior, right-diagonal, medial–lateral, and left-diagonal directions. We used a three-dimensional motion capture system employing infrared cameras and the Pedar Flexible Insoles System to characterize the major lower-extremity joint angles, center of body mass, and center of pressure. We found statistically significant differences between the changes in joint angles in the lower extremities in response to dynamic rotation of the participants (P<0.05. The maximum was greater with anterior–posterior and medial–lateral dynamic rotation than with that in other directions (P<0.05. However, there were no statistically significant differences in the frequency of center of body mass deviations from the base of support (P>0.05. These results

  11. A world in balance.

    Science.gov (United States)

    Westing, A H

    1981-01-01

    The objectives of this paper are to define the scope of global population growth within the uncompromising everyday realities of technology, economies, and politics and to demonstrate the intimate between the human population problem and the increasing problem of Nature's destruction. It is hoped that the human species will come to its sense in time to create an adequate standard of living of all of its members in peace and environmental balance. The number of people the world can support is considered in terms of 1) the provision for a standard of living adequate for everyone's health and wellbeing, 2) consideration for wildlife and nature, and 3) reliance on existing levels of technology and politics. Standards of living are suggested for the affluent and the austere. The focus on the discussion is on standards of living, global carrying capacity, the imperatives of population control and respect for nature, humans versus wildlife, and the need for a universal declaration of respect for nature. Carrying capacity is determined by total land area, cultivated land area, forest land area, cereals (grain), and wood. Use per capita of each of the 5 essentials is determined for the affluent or austere standard of living. An affluent standard means that world population would be limited to 2 billion, which is 50% of the current population. An austere standard of living means a limit of 3 billion, or 33% less than the existing population. The unfortunate reality is that today's total population of 4.5 billion is increasing at an annual rate of 1.9% and is not expected to level off until it has increased 3 times. This population growth occurs at the expense of wildlife. Of the total terrestrial animal biomass, humans constitute 4% and domestic livestock 15%, which, in 40 years, will reach a combined 40% and lead to more species extinction. One species of bird or mammal will become extinct for each increase of 220 million people, which happens every 3 years. The solution is

  12. Metal-silicate partitioning during core formation on super-Earths

    Science.gov (United States)

    Schaefer, L. K.; Jacobsen, S. B.; Petaev, M. I.; Sasselov, D. D.; Remo, J. L.

    2015-12-01

    Separation of the Earth into a rocky mantle and metallic Fe core is a problem long studied in the planetary science community (e.g. [1]). The timing of core formation influences the abundances of the siderophile elements found in the Earth's mantle, and the mechanism of core formation influences the degree of chemical equilibration between the rocky mantle and the core at the time of metal separation. However, limited work has been done on formation of metallic cores and its effects on mantle chemistry in rocky planets larger than the Earth. Super-Earths, exoplanets with masses up to ~ 5 Earth masses and radii up to ~1.6-1.7 Earth radii, have significantly larger internal pressures and consequently higher internal temperatures than the Earth, therefore conclusions from Earth-centric studies of core formation may be erroneous. Partitioning coefficients for many of the relevant elements (e.g. Fe, Ni, Si, O, etc.) are available in the literature, but only to relatively low pressures. The relevant pressures for super-Earths are significantly larger. However, data on Fe-O-Ni-Si partitioning at pressures (200-500 GPa) and temperatures relevant to super-Earths have been measured by laser-induced shocks with the ZBL laser at Sandia National Laboratory with a method described in [2]. We will present a model which integrates this data with lower pressure partition coefficients from the literature (e.g. [3],[4],[5]), with special emphasis on Fe and O, to describe partitioning behavior at high pressures and discuss its implications for core size and composition on rocky super-Earths. [1] Ringwood, A.E. (1977) Geochem. J. 11, 111-135. [2] Remo, J.L., Petaev, M.I., Jacobsen, S. B. (2008) LPSC abstract, 1420. [3] Frost, D.J. et al. (2010) JGR, B02202. [4] Kombayashi, T. (2014) JGR, 4164-4177. [5] Rubie, D.C. et al. (2011) EPSL, 301, 31-42. [5

  13. Earth: A Ringed Planet?

    Science.gov (United States)

    Hancock, L. O.; Povenmire, H.

    2010-12-01

    Among the most beautiful findings of the Space Age have been the discoveries of planetary rings. Not only Saturn but also Jupiter, Uranus and Neptune have rings; Saturn’s ring system has structures newly discovered; even Saturn's moon Rhea itself has a ring. All these are apparently supplied by material from the planetary moons (Rhea's ring by Rhea itself). The question naturally arises, why should the Earth not have a ring, and on the other hand, if it does, why has it not been observed? No rings have yet been observed in the inner solar system, but after all, rings in the inner solar system might simply tend to be fainter and more transient than those of the outer solar system: the inner solar system is more affected by the solar wind, and the Sun’s perturbing gravitational influence is greater. J.A. O’Keefe first suggested (1980) that Earth might have a ring system of its own. An Earth ring could account for some climate events. O’Keefe remarked that formation or thickening of a ring system in Earth’s equatorial plane could drive glaciation by deepening the chill of the winter hemisphere. (It is very well established that volcanic dust is an effective agent for the extinction of sunlight; this factor can be overwhelmingly apparent in eclipse observations.) O’Keefe died in 2000 and the speculation was not pursued, but the idea of an Earth ring has a prima facie reasonableness that calls for its renewed consideration. The program of this note is to hypothesize that, as O’Keefe proposed: (a) an Earth ring system exists; (b) it affects Earth's weather and climate; (c) the tektite strewn fields comprise filaments of the ring fallen to Earth's surface on various occasions of disturbance by comets or asteroids. On this basis, and drawing on the world's weather records, together with the Twentieth Century Reanalysis by NCEP/CIRES covering the period 1870-2010 and the geology of the tektite strewn fields, we herein propose the hypothesized Earth ring

  14. Rotation and magnetism of Earth`s inner core

    Energy Technology Data Exchange (ETDEWEB)

    Glatzmaier, G.A. [Los Alamos National Lab., NM (United States); Roberts, P.H. [Univ. of California, Los Angeles, CA (United States)

    1996-12-13

    Three-dimensional numerical simulations of the geodynamo suggest that a super-rotation of Earth`s solid inner core relative to the mantle is maintained by magnetic coupling between the inner core and an eastward thermal wind in the fluid outer core. This mechanism, which is analogous to a synchronous motor, also plays a fundamental role in the generation of Earth`s magnetic field. 18 refs., 6 figs.

  15. Towards magnetic sounding of the Earth's core by an adjoint method

    Science.gov (United States)

    Li, K.; Jackson, A.; Livermore, P. W.

    2013-12-01

    Earth's magnetic field is generated and sustained by the so called geodynamo system in the core. Measurements of the geomagnetic field taken at the surface, downwards continued through the electrically insulating mantle to the core-mantle boundary (CMB), provide important constraints on the time evolution of the velocity, magnetic field and temperature anomaly in the fluid outer core. The aim of any study in data assimilation applied to the Earth's core is to produce a time-dependent model consistent with these observations [1]. Snapshots of these ``tuned" models provide a window through which the inner workings of the Earth's core, usually hidden from view, can be probed. We apply a variational data assimilation framework to an inertia-free magnetohydrodynamic system (MHD) [2]. Such a model is close to magnetostrophic balance [3], to which we have added viscosity to the dominant forces of Coriolis, pressure, Lorentz and buoyancy, believed to be a good approximation of the Earth's dynamo in the convective time scale. We chose to study the MHD system driven by a static temperature anomaly to mimic the actual inner working of Earth's dynamo system, avoiding at this stage the further complication of solving for the time dependent temperature field. At the heart of the models is a time-dependent magnetic field to which the core-flow is enslaved. In previous work we laid the foundation of the adjoint methodology, applied to a subset of the full equations [4]. As an intermediate step towards our ultimate vision of applying the techniques to a fully dynamic mode of the Earth's core tuned to geomagnetic observations, we present the intermediate step of applying the adjoint technique to the inertia-free Navier-Stokes equation in continuous form. We use synthetic observations derived from evolving a geophysically-reasonable magnetic field profile as the initial condition of our MHD system. Based on our study, we also propose several different strategies for accurately

  16. Practical application of pressure regulating technology for fire district in Meiyukou Coal Mine

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-feng; JIA Bao-shan

    2008-01-01

    Based on the simulated laboratory experiment of pressure balance for fire ex-tinguishing, the pressure regulating technology was summarized for the fire district in Meiyukou Coal Mine. The technology includes three measures for air pressure regulation, namely applying the pressure regulating chamber to balance the air pressure of fire district, increasing the air pressure of the working face, and filling the ground surface fractures. A good effect was obtained to prevent and extinguish the fire. When the measures fail to in-crease the pressure of working face or to regulate that of air chamber, the measure to fill the ground surface fractures will play an important role.

  17. Practical application of pressure regulating technology for fire district in Meiyukou Coal Mine

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qing-feng; JIA Bao-shan

    2008-01-01

    Based on the simulated laboratory experiment of pressure balance for fire extinguishing,the pressure regulating technology was summarized for the fire district in Meiyukou Coal Mine.The technology includes three measures for air pressure regulation,namely applying the pressure regulating chamber to balance the air pressure of fire district,increasing the air pressure of the working face,and filling the ground surface fractures.A good effect was obtained to prevent and extinguish the fire.When the measures fail to increase the pressure of working face or to regulate that of air chamber,the measure to fill the ground surface fractures will play an important role.

  18. Effects of Goal-directed Volume Therapy on the Intracranial Pressure and the Balance of Cerebral Oxygen Consumption and Supply in Selective Neurosurgery%目标导向液体治疗在择期神经外科手术中对颅内压和脑氧供需平衡的影响

    Institute of Scientific and Technical Information of China (English)

    田胜兰; 周游; 冯丹

    2015-01-01

    Objective To investigate the effects of goal‐directed volume therapy (GDVT )on the intracranial pressure(ICP) and the balance of cerebral oxygen consumption and supply in selective neurosurgery. Methods Twenty‐four patients sched‐uled for intracranial tumor resection were randomly divided into 2 groups:conventional fluid management group (group C ,n=12) and GDVT group(group G ,n=12). Patients in group C received introperative fluid transfusion according to classical fluid management strategies while those in group G received GDT according to stroke volume variation (SVV) ,guided by Flotrac‐Vigileo system.Mean arterial pressure(MAP) ,heart rate(HR) ,cardiac index(CI) ,ICP ,SVV and jugular bulb oxygen saturation (SjvO2 )were recorded before the anesthesia induction(T1 ) ,at the moment of intubation(T2 ) ,at the moment of opening the hard meninges(T3),1hafteropeningthehardmeninges(T4),andattheendofthesurgery(T5).Thecerebraloxygenextractionra‐tio(CERO2 )was calculated. The duration of surgery ,crystalloid volume ,colloid volume ,blood transfusion volume ,urinary output and bleeding volume were recorded as well.Results The colloid transfusion volume ,the total fluid transfusion volume and uri‐nary output were significantly increased in group G when compared with those in group C (P0.05).Conclusion Goal‐directed fluid therapy optimizes the cardiac preload without increasing the ICP in selective neurosurgery ,and it also improves the balance of cerebral oxygen con‐sumption and supply.%目的:观察目标导向液体治疗在择期神经外科手术中对颅内压和脑氧供需平衡的影响。方法选择择期全麻下行开颅肿瘤切除术的患者24例,随机分为2组:常规输液组(C组,n=12)和目标导向液体治疗组(G组,n=12)。C组按经典输液方案进行术中液体管理;G组在Flortrac/Vigileo系统监测下,以每搏量变异度(SVV)为导向行液体治疗。分别于麻醉诱导前(T1

  19. Earth Science Multimedia Theater

    Science.gov (United States)

    Hasler, A. F.

    1998-01-01

    The presentation will begin with the latest 1998 NASA Earth Science Vision for the next 25 years. A compilation of the 10 days of animations of Hurricane Georges which were supplied daily on NASA to Network television will be shown. NASA's visualizations of Hurricane Bonnie which appeared in the Sept 7 1998 issue of TIME magazine. Highlights will be shown from the NASA hurricane visualization resource video tape that has been used repeatedly this season on network TV. Results will be presented from a new paper on automatic wind measurements in Hurricane Luis from 1 -min GOES images that will appear in the October BAMS. The visualizations are produced by the Goddard Visualization & Analysis Laboratory, and Scientific Visualization Studio, as well as other Goddard and NASA groups using NASA, NOAA, ESA, and NASDA Earth science datasets. Visualizations will be shown from the "Digital-HyperRes-Panorama" Earth Science ETheater'98 recently presented in Tokyo, Paris and Phoenix. The presentation in Paris used a SGI/CRAY Onyx Infinite Reality Super Graphics Workstation at 2560 X 1024 resolution with dual synchronized video Epson 71 00 projectors on a 20ft wide screen. Earth Science Electronic Theater '999 is being prepared for a December 1 st showing at NASA HQ in Washington and January presentation at the AMS meetings in Dallas. The 1999 version of the Etheater will be triple wide with at resolution of 3840 X 1024 on a 60 ft wide screen. Visualizations will also be featured from the new Earth Today Exhibit which was opened by Vice President Gore on July 2, 1998 at the Smithsonian Air & Space Museum in Washington, as well as those presented for possible use at the American Museum of Natural History (NYC), Disney EPCOT, and other venues. New methods are demonstrated for visualizing, interpreting, comparing, organizing and analyzing immense Hyperimage remote sensing datasets and three dimensional numerical model results. We call the data from many new Earth sensing satellites

  20. Elastic anisotropy of Earth's inner core.

    Science.gov (United States)

    Belonoshko, Anatoly B; Skorodumova, Natalia V; Rosengren, Anders; Johansson, Börje

    2008-02-08

    Earth's solid-iron inner core is elastically anisotropic. Sound waves propagate faster along Earth's spin axis than in the equatorial plane. This anisotropy has previously been explained by a preferred orientation of the iron alloy hexagonal crystals. However, hexagonal iron becomes increasingly isotropic on increasing temperature at pressures of the inner core and is therefore unlikely to cause the anisotropy. An alternative explanation, supported by diamond anvil cell experiments, is that iron adopts a body-centered cubic form in the inner core. We show, by molecular dynamics simulations, that the body-centered cubic iron phase is extremely anisotropic to sound waves despite its high symmetry. Direct simulations of seismic wave propagation reveal an anisotropy of 12%, a value adequate to explain the anisotropy of the inner core.

  1. What is flux balance analysis?

    OpenAIRE

    Orth, Jeffrey D.; Thiele, Ines; Palsson, Bernhard Ø

    2010-01-01

    Flux balance analysis is a mathematical approach for analyzing the flow of metabolites through a metabolic network. This primer covers the theoretical basis of the approach, several practical examples and a software toolbox for performing the calculations.

  2. Efficient codes and balanced networks.

    Science.gov (United States)

    Denève, Sophie; Machens, Christian K

    2016-03-01

    Recent years have seen a growing interest in inhibitory interneurons and their circuits. A striking property of cortical inhibition is how tightly it balances excitation. Inhibitory currents not only match excitatory currents on average, but track them on a millisecond time scale, whether they are caused by external stimuli or spontaneous fluctuations. We review, together with experimental evidence, recent theoretical approaches that investigate the advantages of such tight balance for coding and computation. These studies suggest a possible revision of the dominant view that neurons represent information with firing rates corrupted by Poisson noise. Instead, tight excitatory/inhibitory balance may be a signature of a highly cooperative code, orders of magnitude more precise than a Poisson rate code. Moreover, tight balance may provide a template that allows cortical neurons to construct high-dimensional population codes and learn complex functions of their inputs.

  3. Appetite and energy balancing.

    Science.gov (United States)

    Rogers, Peter J; Brunstrom, Jeffrey M

    2016-10-01

    pleasure of eating it. The latter, which is similar to food reward, is determined primarily by the state of emptiness of the gut and food liking related to the food's sensory qualities and macronutrient value and the individual's dietary history. Importantly, energy density adds value because energy dense foods are less satiating kJ for kJ and satiation limits further intake. That is, energy dense foods promote energy intake by virtue (1) of being more attractive and (2) having low satiating capacity kJ for kJ, and (1) is partly a consequence of (2). Energy storage is adapted to feast and famine and that includes unevenness over time of the costs of obtaining and ingesting food compared with engaging in other activities. However, in very low-cost food environments with energy dense foods readily available, risk of obesity is high. This risk can be and is mitigated by dietary restraint, which in its simplest form could mean missing the occasional meal. Another strategy we discuss is the energy dilution achieved by replacing some sugar in the diet with low-calorie sweeteners. Perhaps as or more significant, though, is that belief in short-term energy balancing (the energy depletion model) may undermine attempts to eat less. Therefore, correcting narratives of eating to be consistent with biological reality could also assist with weight control.

  4. Balancer effects in opinion dynamics

    CERN Document Server

    Cheon, Taksu

    2016-01-01

    We introduce a novel type of contrarian agent, the balancer, to Galam model of opinion dynamics, in order to account for the skepticism over one-sidedness and for the sense of fairness. We find that the inclusion of balancers along with floaters and inflexibles brings about a critical point on parametric plane of the dynamical system, which results in the new kind of stable final states of the opinion dynamics, that seem to capture several intriguing features found often in mature democracies.

  5. The 2013 social balance sheet

    OpenAIRE

    Pierrette Heuse

    2014-01-01

    The transposition into national law of Directive 2013/34/EU on the annual financial statements of companies, expected by no later than July 2015, could alter the statistical obligations on small firms in connection with the filing of their annual accounts. In any case, the social balance sheet can no longer form an integral part of their accounts. Nevertheless, it contains original information whose usefulness is highlighted, on the basis of the social balance sheets for 2012, by examining th...

  6. Internet Load and Traffic Balancing

    Institute of Scientific and Technical Information of China (English)

    李文正; 郭巧; 郭为民

    2005-01-01

    Load and traffic balancing for the Internet are analyzed. An intelligent domain name system(DNS) policy for the control and management of content distribution networks (CDN) is presented. An CDNs network based Urtitech IntelliDNS is built, and performance of the network in realizing traffic and load balancing is measured. It is proved that CDNs provide a valuable service and the methods are feasible.

  7. Hatha yoga on body balance

    OpenAIRE

    Erick Tadeu Prado; Vagner Raso; Renata Coelho Scharlach; Cristiane Akemi Kasse

    2014-01-01

    Background: A good body balance requires a proper function of vestibular, visual, and somatosensory systems which can be reach with exercise practice and/or yoga. Aim: To determine the effects of a 5-month hatha yoga training program on body balance in young adults. Materials and Methods: This study used a controlled, nonrandomized design, where the experimental group underwent a 5-month training program and were then compared with the control group that had a sedentary lifestyle. A c...

  8. The Evolution and Future of Earth's Nitrogen Cycle

    DEFF Research Database (Denmark)

    Canfield, Donald Eugene; Glazer, Alexander N.; Falkowski, Paul G.

    2010-01-01

    Atmospheric reactions and slow geological processes controlled Earth's earliest nitrogen cycle, and by similar to 2.7 billion years ago, a linked suite of microbial processes evolved to form the modern nitrogen cycle with robust natural feedbacks and controls. Over the past century, however...... will ultimately restore balance to the nitrogen cycle, but the damage done by humans to the nitrogen economy of the planet will persist for decades, possibly centuries, if active intervention and careful management strategies are not initiated....

  9. Classroom Racial Balance and Students' Interracial Attitudes

    Science.gov (United States)

    Koslin, Sandra; And Others

    1972-01-01

    Relationships between classroom racial balance and third graders' interracial attitudes were analyzed. Interracial attitudes were more favorable in balanced than in unbalanced classes. Results suggest that classroom racial balance is strongly related to students' interracial attitudes. (Author)

  10. Crystal structures at high pressures and temperatures

    Science.gov (United States)

    Caldwell, Wendel Alexander

    2000-10-01

    The diamond anvil cell (DAC) is a unique instrument that can generate pressures equivalent to those inside planetary interiors (pressures on the order of 1 million atmospheres) under sustained conditions. When combined with a bright source of collimated x-rays, the DAC can be used to probe the structure of materials in-situ at ultra-high pressures. An understanding of the high-pressure structure of materials is important in determining what types of processes may take place in the Earth at great depths. Motivated by previous studies showing that xenon becomes metallic at pressures above ˜1 megabar (100 GPa), we examined the stable structures and reactivity of xenon at pressures approaching that of the core-mantle boundary in the Earth. Our findings indicate the transformation of xenon from face-centered cubic (fcc) to hexagonal close-packed (hcp) structures is kinetically hindered at room temperature, with the equilibrium fcc--hcp phase boundary at 21 (+/-3) gigapascals, a pressure lower than was previously thought. Additionally, we find no tendency on the part of xenon to form a metal alloy with iron or platinum to at least 100 to 150 gigapascals, making it unlikely that the Earth's core serves as a reservoir for primordial xenon. Measurements of the compressibility of natural (Mg.75,Fe .25)2SiO4 gamma-spinel at pressures of the Earth's transition zone yield a pressure derivative of the bulk modulus K0 ' = 6.3 (+/-0.3). As gamma-spinel is considered to be a dominant mineral phase of the transition-zone of the Earth's mantle (400--670 km depth), the relatively high value of K0' for gamma-spinel may help explain the rapid increase with depth of seismic velocities through the transition zone. The thermodynamics, mechanisms and kinetics of pressure-induced amorphization are not well understood. We report here new studies indicating little or no entropy difference between the crystalline and glassy states of Ca(OH) 2 (portlandite). Additional work on the pressure

  11. HII REGIONS IN HYDROSTATIC BALANCE BETWEEN GAS PRESSURE, RADIATION PRESSURE AND GRAVITY

    Directory of Open Access Journals (Sweden)

    A. C. Raga

    2015-01-01

    Full Text Available Estudiamos las soluciones de una versión modificada de la ecuación de Lane-Emden isotérmica, la cual incorpora el efecto de la presión de radiación (dirigida hacia afuera asociada a las fotoionizaciones. Estas soluciones son relevantes para regiones HII alrededor de un cúmulo con ≈500 estrellas O, que puede fotoionizar el gas hasta distancias de ≈ pc (siendo n0 la densidad central del gas, donde son importantes los efectos tanto de la autogravedad como de la presión de radiación. Encontramos que las soluciones tienen una transición de un régimen "dominado por gravedad" (en el que las soluciones convergen a radios grandes a la solución de la esfera isotérmica autogravitante no singular a uno "dominado por presión de radiación" (en el que la densidad diverge a un radio finito para regiones HII con densidades centrales mayores que ncrit = 100 cm -3. Argumentamos que las soluciones con densidades centrales altas, dominadas por presión de radiación, no ocurrirán en muchas de las situaciones astrofísicamente relevantes, dada la ausencia de un posible medio confinador de presión suficientemente alta.

  12. Ion Acceleration at Earth, Saturn and Jupiter and its Global Impact on Magnetospheric Structure

    Science.gov (United States)

    Brandt, Pontus

    2016-07-01

    The ion plasma pressures at Earth, Saturn and Jupiter are significant players in the electrodynamic force-balance that governs the structure and dynamics of these magnetospheres. There are many similarities between the physical mechanisms that are thought to heat the ion plasma to temperatures that even exceed those of the solar corona. In this presentation we compare the ion acceleration mechanisms at the three planetary magnetospheres and discuss their global impacts on magnetopsheric structure. At Earth, bursty-bulk flows, or "bubbles", have been shown to accelerate protons and O+ to high energies by the earthward moving magnetic dipolarization fronts. O+ ions display a more non-adiabatic energization in response to these fronts than protons do as they are energized and transported in to the ring-current region where they reach energies of several 100's keV. We present both in-situ measurements from the NASA Van Allen Probes Mission and global Energetic Neutral (ENA) images from the High-Energy Neutral Atom (HENA) Camera on board the IMAGE Mission, that illustrate these processes. The global impact on the magnetospheric structure is explored by comparing the empirical magnetic field model TS07d for given driving conditions with global plasma pressure distributions derived from the HENA images. At Saturn, quasi-periodic energization events, or large-scale injections, occur beyond about 9 RS around the post-midnight sector, clearly shown by the Ion and Neutral Atom Camera (INCA) on board the Cassini mission. In contrast to Earth, the corotational drift dominates even the energetic ion distributions. The large-scale injections display similar dipolarization front features can be found and there are indications that like at Earth the O+ responds more non-adiabatically than protons do. However, at Saturn there are also differences in that there appears to be energization events deep in the inner magnetosphere (6-9 RS) preferentially occurring in the pre

  13. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ February, 2010 Rare earth separation plants and downstream producers like NdFeB magnetic materials and phosphor materials successively ceased production due to Spring Festival, Chinese New Year. Transactions in rare earth market were few affected by public holidays.

  14. Mirador - Earth Surface and Interior

    Data.gov (United States)

    National Aeronautics and Space Administration — Earth Science data access made simple. The goal of the Earth Surface and Interior focus area is to assess, mitigate and forecast the natural hazards that affect...

  15. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Active demands from downstream industry drove the price rise of rare earth products in Chinese domestic marketrecently, particularly didymium and dysprosium products. Prices of other rare earth products remained stable.

  16. China rare earth market review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Rare earth market fluctuated slightly recently and the transactions remained sluggish. Environment control was strengthened in southern China and many rare earth plants had gone out of production. Some traders were considering selling commodities at low p

  17. Heat-pipe Earth.

    Science.gov (United States)

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

  18. NASA Benefits Earth

    Science.gov (United States)

    Robinson, Julie A.

    2009-01-01

    This slide presentation reviews several ways in which NASA research has benefited Earth and made life on Earth better. These innovations include: solar panels, recycled pavement, thermometer pill, invisible braces for straightening teeth, LASIK, aerodynamic helmets and tires for bicycles, cataract detection, technology that was used to remove Anthrax spores from mail handling facilities, study of atomic oxygen erosion of materials has informed the restoration of artwork, macroencapsulation (a potential mechanism to deliver anti cancer drugs to specific sites), and research on a salmonella vaccine. With research on the International Space Station just beginning, there will be opportunities for entrepreneurs and other government agencies to access space for their research and development. As well as NASA continuing its own research on human health and technology development.

  19. Life Before Earth

    CERN Document Server

    Sharov, Alexei A

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization, and emergence of novel functional niches associated with existing genes. Linear regression of genetic complexity on a log scale extrapolated back to just one base pair suggests the time of the origin of life 9.7 billion years ago. This cosmic time scale for the evolution of life has important consequences: life took ca. 5 billion years to reach the complexity of bacteria; the environments in which life originated and evolved to the prokaryote stage may have been quite different from those envisaged on Earth; there was no...

  20. 25th Space Simulation Conference. Environmental Testing: The Earth-Space Connection

    Science.gov (United States)

    Packard, Edward

    2008-01-01

    Topics covered include: Methods of Helium Injection and Removal for Heat Transfer Augmentation; The ESA Large Space Simulator Mechanical Ground Support Equipment for Spacecraft Testing; Temperature Stability and Control Requirements for Thermal Vacuum/Thermal Balance Testing of the Aquarius Radiometer; The Liquid Nitrogen System for Chamber A: A Change from Original Forced Flow Design to a Natural Flow (Thermo Siphon) System; Return to Mercury: A Comparison of Solar Simulation and Flight Data for the MESSENGER Spacecraft; Floating Pressure Conversion and Equipment Upgrades of Two 3.5kw, 20k, Helium Refrigerators; Affect of Air Leakage into a Thermal-Vacuum Chamber on Helium Refrigeration Heat Load; Special ISO Class 6 Cleanroom for the Lunar Reconnaissance Orbiter (LRO) Project; A State-of-the-Art Contamination Effects Research and Test Facility Martian Dust Simulator; Cleanroom Design Practices and Their Influence on Particle Counts; Extra Terrestrial Environmental Chamber Design; Contamination Sources Effects Analysis (CSEA) - A Tool to Balance Cost/Schedule While Managing Facility Availability; SES and Acoustics at GSFC; HST Super Lightweight Interchangeable Carrier (SLIC) Static Test; Virtual Shaker Testing: Simulation Technology Improves Vibration Test Performance; Estimating Shock Spectra: Extensions beyond GEVS; Structural Dynamic Analysis of a Spacecraft Multi-DOF Shaker Table; Direct Field Acoustic Testing; Manufacture of Cryoshroud Surfaces for Space Simulation Chambers; The New LOTIS Test Facility; Thermal Vacuum Control Systems Options for Test Facilities; Extremely High Vacuum Chamber for Low Outgassing Processing at NASA Goddard; Precision Cleaning - Path to Premier; The New Anechoic Shielded Chambers Designed for Space and Commercial Applications at LIT; Extraction of Thermal Performance Values from Samples in the Lunar Dust Adhesion Bell Jar; Thermal (Silicon Diode) Data Acquisition System; Aquarius's Instrument Science Data System (ISDS) Automated

  1. Mission to Planet Earth

    Science.gov (United States)

    Tilford, Shelby G.; Wilson, Gregory S.; Backlund, Peter W.

    1991-01-01

    The NASA program described is an international study to predict changes in the earth's environment by means of multidisciplinary remote sensing from satellites. An international consortium dedicates satellites with advanced sensors to data collection, and a data processing system is described to collect and analyze a large amount of terrestrial data. The program requires international multidisciplinary involvement to collect and interpret the data and thereby manage and preserve the global environment.

  2. Life Before Earth

    OpenAIRE

    Sharov, Alexei A; Gordon, Richard

    2013-01-01

    An extrapolation of the genetic complexity of organisms to earlier times suggests that life began before the Earth was formed. Life may have started from systems with single heritable elements that are functionally equivalent to a nucleotide. The genetic complexity, roughly measured by the number of non-redundant functional nucleotides, is expected to have grown exponentially due to several positive feedback factors: gene cooperation, duplication of genes with their subsequent specialization,...

  3. Testing MOND on Earth

    CERN Document Server

    Ignatiev, A Yu

    2014-01-01

    MOND is one of the most popular alternatives to Dark Matter (DM). While efforts to directly detect DM in laboratories have been steadily pursued over the years, the proposed Earth-based tests of MOND are still in their infancy. Some proposals recently appeared in the literature are briefly reviewed, and it is argued that collaborative efforts of theorists and experimenters are needed to move forward in this exciting new area. Possible future directions are outlined.

  4. Why Earth aurorae shine?

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    @@ By using the data obtained from three satellites of the Cluster mission launched by the European Space Agency (ESA), CAO Jinbin from the CAS Center for Space Science and Applied Research (CSSAR) and his US and European co-workers have clarified why Earth's aurorae shine.Their work entitled Joint Observations by Cluster Satellites of Bursty Bulk Flows in the Magnetotail was published in a recent issue of Journal of Geophysical Research.

  5. USSR Report, Earth Sciences.

    Science.gov (United States)

    2007-11-02

    Auroras (Yu. K. Krakovetskiy, Yu. A. Nadubovich, et al.; DOKLADY AKADEMII NAUK SSSR, No 3, Nov 84) 101 ’Full-Shadow’ Phenomenon in Earth’s Upper...populations are characteristic for tropical, Atlantic boreal and high-arctic oceanic communi- ties. In the Norwegian-Sea and in the polar basin... boreal community and probably is close to that in other oceanic tropical regions. The variability of the species within the limits of the entire range

  6. Hunan Rare Earth Group Approved

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Following Guangdong,Guangxi,Fujian and Jiangxi,Hunan announced that it would consolidate its rare earth resources-the consolidation plan of Hunan Rare Earth Group has been approved. Consolidation of the rare earth industry of south China is in full swing.According to "Several Opinions of the State Council on Promoting the Sustainable and Healthy Development of Rare Earth Industry"(hereinafter referred to as "Several Opinions")released in 2011,

  7. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    September 20-30, 2011 Rare earth market remained steady recently. Quoted prices of didymium products by separation and smelting plants kept stable. Some rare earth industrial zones in Baotou, Sichuan and Ganzhou had suspended production with the intensified environmental protection control and consolidation of rare earth industry. Persons in the industry hold a positive attitude toward the rare earth market after the National Day' s holiday in China. The market will develop healthily and orderly in the future.

  8. Postural balance in low back pain patients

    DEFF Research Database (Denmark)

    Maribo, Thomas; Schiøttz-Christensen, Berit; Jensen, Lone Donbæk

    2012-01-01

    INTRODUCTION: Altered postural control has been observed in low back pain (LBP) patients. They seem to be more dependent on vision when standing. The objective of the study was to determine concurrent and predictive validity of measures of postural stability in LBP patients. MATERIALS AND METHODS......: Centre of Pressure (CoP) measurements were tested against pain, fear of pain, and physical function. Velocity, anterior-posterior displacement, and the Romberg Ratio obtained on a portable force platform were used as measures of postural stability. RESULTS: Baseline and 12-week follow-up results of 97....... CONCLUSION: This first study of concurrent and predictive validity of postural balance in LBP patients revealed no association between CoP measures and pain, fear of pain, and physical function....

  9. Afganistan and rare earths

    Directory of Open Access Journals (Sweden)

    Emilian M. Dobrescu

    2013-05-01

    Full Text Available On our planet, over a quarter of new technologies for the economic production of industrial goods, are using rare earths, which are also called critical minerals and industries that rely on these precious items being worth of an estimated nearly five trillion dollars, or 5 percent of world gross domestic product. In the near future, competition will increase for the control of rare earth minerals embedded in high-tech products. Rare minerals are in the twenty-first century what oil accounted for in the twentieth century and coal in the nineteenth century: the engine of a new industrial revolution. Future energy will be produced increasingly by more sophisticated technological equipment based not just on steel and concrete, but incorporating significant quantities of metals and rare earths. Widespread application of these technologies will result in an exponential increase in demand for such minerals, and what is worrying is that minerals of this type are almost nowhere to be found in Europe and in other industrialized countries in the world, such as U.S. and Japan, but only in some Asian countries, like China and Afghanistan.

  10. Earth System Monitoring, Introduction

    Science.gov (United States)

    Orcutt, John

    This section provides sensing and data collection methodologies, as well as an understanding of Earth's climate parameters and natural and man-made phenomena, to support a scientific assessment of the Earth system as a whole, and its response to natural and human-induced changes. The coverage ranges from climate change factors and extreme weather and fires to oil spill tracking and volcanic eruptions. This serves as a basis to enable improved prediction and response to climate change, weather, and natural hazards as well as dissemination of the data and conclusions. The data collection systems include satellite remote sensing, aerial surveys, and land- and ocean-based monitoring stations. Our objective in this treatise is to provide a significant portion of the scientific and engineering basis of Earth system monitoring and to provide this in 17 detailed articles or chapters written at a level for use by university students through practicing professionals. The reader is also directed to the closely related sections on Ecological Systems, Introduction and also Climate Change Modeling Methodology, Introduction as well as Climate Change Remediation, Introduction to. For ease of use by students, each article begins with a glossary of terms, while at an average length of 25 print pages each, sufficient detail is presented for use by professionals in government, universities, and industries. The chapters are individually summarized below.

  11. EARTH ROADS ARE EASY

    Directory of Open Access Journals (Sweden)

    David O. Whitten

    2000-01-01

    Full Text Available The earliest European immigrants in America traveled on waterways and on pathways worn into the earth by animals and Native Americans. Once their communities began to thrive, settlers widened paths and cleared new roads and streets then began experimenting with inexpensive surfacing to reduce dust in dry weather and mud in wet. “Earth Roads Are Easy” investigates materials and techniques used to maintain primitive thoroughfares with a minimum of effort and expense. The options range from the mundane—clay, sand, gravel, calcium chloride, oil, and tar—to the extraordinary—water glass, adobe clay, beet juice, and carpeting.There is no more dfficult problem confronting highway engineers than that of properly constructing and maintaining an earth road. The work may be less spectacular than the construction and maintenance of hard-surfaced roads, but there is greater latitude in location, methods of construction and choice of materials, consequently there is more scope for the exercise of sound judgment on the part of the engineer.1

  12. The Active Solid Earth

    Science.gov (United States)

    Ebinger, Cynthia

    2016-04-01

    Dynamic processes in Earth's crust, mantle and core shape Earth's surface and magnetic field over time scales of seconds to millennia, and even longer time scales as recorded in the ca. 4 Ga rock record. Our focus is the earthquake-volcano deformation cycles that occur over human time scales, and their comparison with time-averaged deformation studies, with emphasis on mantle plume provinces where magma and volatile release and vertical tectonics are readily detectable. Active deformation processes at continental and oceanic rift and back arc zones provide critical constraints on mantle dynamics, the role of fluids (volatiles, magma, water), and plate rheology. For example, recent studies of the East African rift zone, which formed above one of Earth's largest mantle upwellings reveal that magma production and volatile release rates are comparable to those of magmatic arcs, the archetypal zones of continental crustal creation. Finite-length faults achieve some plate deformation, but magma intrusion in the form of dikes accommodates extension in continental, back-arc, and oceanic rifts, and intrusion as sills causes permanent uplift that modulates the local time-space scales of earthquakes and volcanoes. Volatile release from magma intrusion may reduce fault friction and permeability, facilitating aseismic slip and creating magma pathways. We explore the implications of active deformation studies to models of the time-averaged structure of plume and extensional provinces in continental and oceanic plate settings.

  13. Characterising Super-Earths

    Directory of Open Access Journals (Sweden)

    Valencia D.

    2011-02-01

    Full Text Available The era of Super-Earths has formally begun with the detection of transiting low-mass exoplanets CoRoT-7b and GJ 1214b. In the path of characterising super-Earths, the first step is to infer their composition. While the discovery data for CoRoT-7b, in combination with the high atmospheric mass loss rate inferred from the high insolation, suggested that it was a rocky planet, the new proposed mass values have widened the possibilities. The combined mass range 1−10 M⊕ allows for a volatile-rich (and requires it if the mass is less than 4 M⊕ , an Earth-like or a super-Mercury-like composition. In contrast, the radius of GJ 1214b is too large to admit a solid composition, thus it necessarily to have a substantial gas layer. Some evidence suggests that within this gas layer H/He is a small but non-negligible component. These two planets are the first of many transiting low-mass exoplanets expected to be detected and they exemplify the limitations faced when inferring composition, which come from the degenerate character of the problem and the large error bars in the data.

  14. Sun, Earth and Sky

    CERN Document Server

    Lang, Kenneth R

    2006-01-01

    This Second Edition of Sun, Earth and Sky updates the popular text by providing comprehensive accounts of the most recent discoveries made by five modern solar spacecraft during the past decade. Their instruments have used sound waves to peer deep into the Sun’s inner regions and measure the temperature of its central nuclear reactor, and extended our gaze far from the visible Sun to record energetic outbursts that threaten Earth. Breakthrough observations with the underground Sudbury Neutrino Observatory are also included, which explain the new physics of ghostly neutrinos and solve the problematic mismatch between the predicted and observed amounts of solar neutrinos. This new edition of Sun, Earth and Sky also describes our recent understanding of how the Sun’s outer atmosphere is heated to a million degrees, and just where the Sun’s continuous winds come from. As humans we are more intimately linked with our life-sustaining Sun than with any other astronomical object, and the new edition therefore p...

  15. GPS Radio Occultation: A Potential New Data Source for Improvement of Antarctic Pressure Field

    Institute of Scientific and Technical Information of China (English)

    Ge Sheng-jie; C. K. Shum; J. Wickert; Ch. Reigber

    2003-01-01

    Radio occultation technique, first demonstrated by the GPS/MET experiment in 1995[1], has the potential to provide improved spatial and temporal resolution in the probing of the Earth's neutral atmosphere, including pressure,temperature and water vapor profiles, in addition to traditional measurements (e.g.,radiosonde, spaceborne radiometers) and ground-based GPS networks for precipitable water vapor (PWV) measurements. This paper provides an overview of the radio occultation concept and retrieval procedure and current technical limitations including lower troposphere inhomogeneities, signal penetration, multipath, and water vapor ambiguity. The current limitations using atmospheric model pressure fields (ECMWF and NCEP) for the modeling of atmospheric mass load over Antarctica, for its separation from climate sensitive signals observed by gravity mapping satellite,GRACE, are quantified. Atmospheric pressure fields over Antarctica are poorly known and higher temporal variability of pressure causes an "aliasing" error in GRACE-observed climate-sensitive signals such as hydrology, mass balance and oceanic mass variations. In particular, comparison of ECMWF 6-hour data with the Automatic Weather Station (AWS) in Antarctica indicates mean differences of 5 hPa,and rms of 1.7 hPa, exceeding the accuracy requirement for GRACE. Aliasing effec tmanifests as high-frequency errors in GRACE-observed gravity signals and are more pronounced over Antarctica. The possibility of using current operating satellite(SAC-C, CHAMP and GRACE) occultation data to improve Antarctic surface pressure fields is proposed. Preliminary results indicate that in the absence of water vapor over Antarctica, retrieved CHAMP pressure profile agrees well with radiosonde data from Neumayer station, and that occultation signals reach near the surface.

  16. China Rare Earth Market Review

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Supply of rare earth concentrate remained tight recently. Rare earth market exhibited rising tendency holistically Affected by tight supply of rare earth concentrate, many plants were operated under the capacity. Supply of didymium oxide got tighter and the price was on rising.

  17. Mantle Dynamics in Super-Earths: Post-Perovskite Rheology and Self-Regulation of Viscosity

    CERN Document Server

    Tackley, Paul J; Brodholt, John P; Dobson, David P; Valencia, Diana

    2012-01-01

    Simple scalings suggest that super-Earths are more likely than an equivalent Earth-sized planet to be undergoing plate tectonics. Generally, viscosity and thermal conductivity increase with pressure while thermal expansivity decreases, resulting in lower convective vigor in the deep mantle. According to conventional thinking, this might result in no convection in a super-Earth's deep mantle. Here we evaluate this. First, we here extend the density functional theory (DFT) calculations of post-perovskite activation enthalpy of to a pressure of 1 TPa. The activation volume for diffusion creep becomes very low at very high pressure, but nevertheless for the largest super-Earths the viscosity along an adiabat may approach 1030 Pa s in the deep mantle. Second, we use these calculated values in numerical simulations of mantle convection and lithosphere dynamics of planets with up to ten Earth masses. The models assume a compressible mantle including depth-dependence of material properties and plastic yielding induce...

  18. Galactic Cosmic Rays - Clouds Effect and Bifurcation Model of the Earth Global Climate. Part 2. Comparison of Theory with Experiment

    CERN Document Server

    Rusov, V; Vaschenko, V; Mihalys, O; Kosenko, S; Mavrodiev, S; Vachev, B

    2008-01-01

    The solution of the energy-balance model of the Earth's global climate proposed in Ref. [1] is compared with well-known experimental data on the palaeotemperature evolution of Earth's surface over past 420 kyr and 740 kyr obtained in the framework of Antarctic projects the EPICA Dome C and Vostok. The Solar-Earth mechanism of anomalous temperature jumps observed in the EPICA Dome C and Vostok experiments and its relation with the "order-chaos" transitions in convection evolution in the liquid Earth core responsible to the mechanism of the Earth magnetic field inversions was discussed. The stabilizing role of the slow nuclear burning on the boundary of the liquid and solid phases of the Earth's core (georeactor with power of 30 TW) for convection evolution in the liquid Earth's core and hence in the Earth's magnetic field evolution is pointed out.

  19. Independent effects of adding weight and inertia on balance during quiet standing

    Directory of Open Access Journals (Sweden)

    Costello Kerry

    2012-04-01

    Full Text Available Abstract Background Human balance during quiet standing is influenced by adding mass to the body with a backpack, with symmetrically-applied loads to the trunk, or with obesity. Adding mass to the body increases both the weight and inertia of the body, which theoretically could provide counteracting effects on body dynamics and balance. Understanding the independent effects of adding weight and inertia on balance may provide additional insight into human balance that could lead to novel advancements in balance training and rehabilitation. Therefore, the purpose of this study was to investigate the independent effects of adding weight and inertia on balance during quiet standing. Methods Sixteen normal-weight young adult participants stood as still as possible on a custom-built backboard apparatus under four experimental conditions: baseline, added inertia only, added weight only, and added inertia and weight. Results Adding inertia by itself had no measurable effect on center of pressure movement or backboard movement. Adding weight by itself increased center of pressure movement (indicated greater effort by the postural control system to stand as still as possible and backboard movement (indicating a poorer ability of the body to stand as still as possible. Adding inertia and weight at the same time increased center of pressure movement but did not increase backboard movement compared to the baseline condition. Conclusions Adding inertia and adding weight had different effects on balance. Adding inertia by itself had no effect on balance. Adding weight by itself had a negative effect on balance. When adding inertia and weight at the same time, the added inertia appeared to lessen (but did not eliminate the negative effect of adding weight on balance. These results improve our fundamental understanding of how added mass influences human balance.

  20. Strategy for earth explorers in global earth sciences

    Science.gov (United States)

    1988-01-01

    The goal of the current NASA Earth System Science initiative is to obtain a comprehensive scientific understanding of the Earth as an integrated, dynamic system. The centerpiece of the Earth System Science initiative will be a set of instruments carried on polar orbiting platforms under the Earth Observing System program. An Earth Explorer program can open new vistas in the earth sciences, encourage innovation, and solve critical scientific problems. Specific missions must be rigorously shaped by the demands and opportunities of high quality science and must complement the Earth Observing System and the Mission to Planet Earth. The committee believes that the proposed Earth Explorer program provides a substantial opportunity for progress in the earth sciences, both through independent missions and through missions designed to complement the large scale platforms and international research programs that represent important national commitments. The strategy presented is intended to help ensure the success of the Earth Explorer program as a vital stimulant to the study of the planet.