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Sample records for horizontal displacements modelled

  1. Numerical Modelling of the Mining Induced Horizontal Displacement

    NASA Astrophysics Data System (ADS)

    Tajduś, Krzysztof

    2015-12-01

    The paper presents results of numerical calculations and modeling of mining-induced surface deformation based on Finite Element Method (FEM). Applying the numerical method discussed to calculations allows us to assume a larger number of factors, such as rock mass structure, fracture network, rock properties, etc., which essentially affect the results obtained. On the basis of an elastic transversely isotropic model, an analysis of horizontal displacement distribution and surface subsidence was carried out for two sample regions of mines. The results of numerical calculations were later compared with the measured values. Such an analysis proved that the applied numerical model properly described distribution and values of subsidence and slope of subsidence trough, though there were serious differences in the values of calculated horizontal displacement, especially in areas of far influence range. In order to improve the matching, the influence of boundary conditions of the model on the value of calculated horizontal displacement was analyzed. The results are presented in graphs.

  2. A Theoretical Model to Predict Both Horizontal Displacement and Vertical Displacement for Electromagnetic Induction-Based Deep Displacement Sensors

    PubMed Central

    Shentu, Nanying; Zhang, Hongjian; Li, Qing; Zhou, Hongliang; Tong, Renyuan; Li, Xiong

    2012-01-01

    Deep displacement observation is one basic means of landslide dynamic study and early warning monitoring and a key part of engineering geological investigation. In our previous work, we proposed a novel electromagnetic induction-based deep displacement sensor (I-type) to predict deep horizontal displacement and a theoretical model called equation-based equivalent loop approach (EELA) to describe its sensing characters. However in many landslide and related geological engineering cases, both horizontal displacement and vertical displacement vary apparently and dynamically so both may require monitoring. In this study, a II-type deep displacement sensor is designed by revising our I-type sensor to simultaneously monitor the deep horizontal displacement and vertical displacement variations at different depths within a sliding mass. Meanwhile, a new theoretical modeling called the numerical integration-based equivalent loop approach (NIELA) has been proposed to quantitatively depict II-type sensors’ mutual inductance properties with respect to predicted horizontal displacements and vertical displacements. After detailed examinations and comparative studies between measured mutual inductance voltage, NIELA-based mutual inductance and EELA-based mutual inductance, NIELA has verified to be an effective and quite accurate analytic model for characterization of II-type sensors. The NIELA model is widely applicable for II-type sensors’ monitoring on all kinds of landslides and other related geohazards with satisfactory estimation accuracy and calculation efficiency. PMID:22368467

  3. Mathematical models of cuttings transport and drilling fluid displacement by cement slurry in horizontal wells

    NASA Astrophysics Data System (ADS)

    Nguyen, Desmond

    Arguably the most important prerequisite to a good primary cementing job is mud displacement. In order to have effective mud displacement, complete removal of drilled cuttings from the well bore is required. This becomes more challenging in highly-deviated to horizontal wells where the casing tends to lie on the low side of the well bore creating an eccentric annular flow geometry. In this study, a theoretical approach based on the theory of particles transport and fluid mechanics is adopted to develop two new mathematical models: (1) cuttings transport; and (2) drilling fluid displacement by cement slurry in horizontal wells. Two computer algorithms are developed based on these models. The effects of various operational conditions, hole geometry and fluid properties are simulated using these computer models. The results compare favourably with those obtained by previous investigators. These simulated examples demonstrate that the two models can be used to analyse the sensitivity of the cuttings transport and displacement processes to changes in the operational conditions, hole geometry and fluid properties. Hence, they can potentially be used as design and/or analysis tools for the optimisation of these processes in highly- deviated to horizontal wells.

  4. Some Considerations on Horizontal Displacement and Horizontal Displacement Coefficient B

    NASA Astrophysics Data System (ADS)

    Tajduś, Krzysztof; Tajduś, Antoni

    2015-12-01

    Mining-induced deformations of the ground surface and within the rock mass may pose danger not only for surface constructions but also for underground objects (e.g., tunnels, underground storages, garages), diverse types of pipelines, electric cables, etc. For a proper evaluation of hazard for surface and underground objects, such parameters as horizontal displacement and horizontal deformations, especially their maximum values, are of crucial importance. The paper is an attempt at a critical review of hitherto accomplished studies and state of the art of predicting horizontal displacement u, in particular the coefficient B, whose value allows determination of the value of maximum displacement if the value of maximum slope is known, or the value of maximum deformation if the value of maximum trough slope is recognized. Since the geodesic observations of fully developed subsidence troughs suggest that the value of the coefficient depends on the depth H, radius of main influences range r and properties of overburden rock, in particular the occurrence of sub-eras Paleogene and Neogene layers (old name: Quaternary and Tertiary) with low strength parameters, therefore a formula is provided in the present paper allowing for the estimation of the influence of those factors on the value of coefficient B.

  5. Seismic transducer measures small horizontal displacements

    NASA Technical Reports Server (NTRS)

    Greenwood, T. L.

    1965-01-01

    Pendular seismic transducer mounted on base plate measures small horizontal displacements of structures subjected to vibration where no fixed reference point is available. Enclosure of transducer in transparent plastic case prevents air currents from disturbing the pendulum balance.

  6. A semi-empirical model for the estimation of maximum horizontal displacement due to liquefaction-induced lateral spreading

    USGS Publications Warehouse

    Faris, Allison T.; Seed, Raymond B.; Kayen, Robert E.; Wu, Jiaer

    2006-01-01

    During the 1906 San Francisco Earthquake, liquefaction-induced lateral spreading and resultant ground displacements damaged bridges, buried utilities, and lifelines, conventional structures, and other developed works. This paper presents an improved engineering tool for the prediction of maximum displacement due to liquefaction-induced lateral spreading. A semi-empirical approach is employed, combining mechanistic understanding and data from laboratory testing with data and lessons from full-scale earthquake field case histories. The principle of strain potential index, based primary on correlation of cyclic simple shear laboratory testing results with in-situ Standard Penetration Test (SPT) results, is used as an index to characterized the deformation potential of soils after they liquefy. A Bayesian probabilistic approach is adopted for development of the final predictive model, in order to take fullest advantage of the data available and to deal with the inherent uncertainties intrinstiic to the back-analyses of field case histories. A case history from the 1906 San Francisco Earthquake is utilized to demonstrate the ability of the resultant semi-empirical model to estimate maximum horizontal displacement due to liquefaction-induced lateral spreading.

  7. Horizontal displacement profiles in N Reactor horizontal control rod channels

    SciTech Connect

    Woodruff, E.M.

    1988-12-01

    One of the potential results from N Reactor graphite moderator distortion is horizontal curvature of the horizontal control rod (HCR) channels. Mockup testing has identified two possible problem scenarios resulting from such curvature: slow scram times and rod abrasion due to rubbing of the rod on the side of the channel and subsequent displacement of T-blocks that form the sides of the channels. As a result of these potential events, surveillance tools (instrumentation) to measure HCR channel horizontal displacement was recently developed. Surveillance of HCR channel 65, performed on December 11, 1987, indicated a six inch rearward displacement near the center of the channel. This approximated the displacement which mockup testing has identified as a concern with regard to T-block movement. Closed Circuit Television (CCTV) observations indicate that T-block movement has not occurred in HCR channel 65, but that there has been some rubbing of the rod on the channel sides. Review of most recent rod hot scram times indicates normal performance for HCR 65. To further evaluate this concern, horizontal deflection and CCTV surveillance was scheduled in six HCR channels surrounding HCR channel 65. Inspection of the HCR rod tip was also performed. 13 refs., 6 figs.

  8. Application of Inclinometer Measurements for Relative Horizontal Displacement Investigations on Landslide Grounds

    NASA Astrophysics Data System (ADS)

    Malarski, Ryszar; Nagórski, Kamil; Woźniak, Marek

    2013-10-01

    One of the basic criterion for safety evaluation of structures erected on embankment or sliding slopes is relative horizontal displacement at different elevations. Relative horizontal displacements beneath ground surfaces are performed with inclinometer measurements. This report presents results on horizontal relative ground displacements with the probe SISGEO S242SV30. Investigations were performed with two inclinometer columns 14m height embedded in Warsaw Bank Slope. Mean square error of single observation was determined and mean relative errors of relative displacements in relation to column height. On the basis measurement results several relevant recommendations and practical hints were formulated allowing to avoid survey blunders and discrepancies in measuring procedures often encountered. Detailed inclinometer horizontal displacement measurements results at Warsaw hillside St Ana's Church grounds were listed and presented.

  9. A design chart for estimation of horizontal displacement in municipal landfills

    SciTech Connect

    Singh, M.K. Sharma, J.S.; Fleming, I.R.

    2009-05-15

    This paper describes the development of a design chart for the estimation of maximum horizontal displacement within a municipal landfill using the height and the side slope of the landfill. The design chart is based on the results of a finite element parametric study in which the behaviour of the municipal solid waste (MSW) was modeled using a non-linear elastic hyperbolic model. The model input parameters, i.e. non-linear stiffness, shear strength and unit weight of MSW, were obtained from laboratory testing data and an extensive stochastic numerical modelling exercise. Non-linear variations of unit weight as well as Young's modulus of MSW with depth were incorporated in the finite element analyses. The validity of the design chart was assessed using field monitoring results from a large landfill located in Ontario, Canada.

  10. Sliding and rotary PDM drilling keep horizontal well on target. [Positive Displacement Motors

    SciTech Connect

    Johnson, M.L. )

    1993-07-12

    Improved drilling efficiency and the use of steerable positive displacement motors (PDMs) helped keep an Austin chalk horizontal well on target and below cost. Field development in the Austin chalk began more than 60 years ago; however, many wells have had low-to-average oil recovery. Recent thorough studies of the natural fracture matrix in the Austin chalk revealed that the fractures were not interconnected. The ability of a horizontal well to intersect numerous fracture systems made the Austin chalk an excellent candidate for horizontal drilling. This paper describes the well plan, its trajectory, bottom hole assemblies, and drilling results.

  11. Horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications.

    PubMed

    Ma, Hongcai; Wu, Lin

    2015-07-10

    We present the design of a horizontally staggered lightguide solar concentrator with lateral displacement tracking for high concentration applications. This solar concentrator consists of an array of telecentric primary concentrators, a horizontally staggered lightguide layer, and a vertically tapered lightguide layer. The primary concentrator is realized by two plano-aspheric lenses with lateral movement and maintains a high F-number over an angle range of ±23.5°. The results of the simulations show that the solar concentrator achieves a high concentration ratio of 500× with ±0.5° of acceptance angle by a single-axis tracker and dual lateral translation stages. PMID:26193396

  12. Long-delayed bright dancing sprite with large horizontal displacement from its parent flash

    NASA Astrophysics Data System (ADS)

    Yang, J.; Lu, G.; Lee, L. J.; Feng, G.

    2015-12-01

    A long-delayed very bright dancing sprite with large horizontal displacement from its parent flash was observed. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large sprite element in the third field, different from other observations. The bright sprite displaced at least 38 km from its parent flash and occurred over comparatively higher cloud top region. The parent flash was positive, with only one return stroke (~24 kA) and obvious continuing current process, and the charge moment change of the stroke was small (roughly the threshold for sprite production). All of the sprite elements occurred during the continuing current period, and the bright sprite induced considerable current. The sprite dancing features may be linked to parent storm electrical structure, dynamics and microphysics, and the parent CG discharge process which was consistent with VHF observations.

  13. Modelling Toehold-Mediated RNA Strand Displacement

    PubMed Central

    Šulc, Petr; Ouldridge, Thomas E.; Romano, Flavio; Doye, Jonathan P.K.; Louis, Ard A.

    2015-01-01

    We study the thermodynamics and kinetics of an RNA toehold-mediated strand displacement reaction with a recently developed coarse-grained model of RNA. Strand displacement, during which a single strand displaces a different strand previously bound to a complementary substrate strand, is an essential mechanism in active nucleic acid nanotechnology and has also been hypothesized to occur in vivo. We study the rate of displacement reactions as a function of the length of the toehold and temperature and make two experimentally testable predictions: that the displacement is faster if the toehold is placed at the 5′ end of the substrate; and that the displacement slows down with increasing temperature for longer toeholds. PMID:25762335

  14. Long-delayed bright dancing sprite with large Horizontal displacement from its parent flash

    NASA Astrophysics Data System (ADS)

    Yang, Jing; Lu, Gaopeng; Lee, Li-Jou; Feng, Guili

    2015-07-01

    We reported in this paper the observation of a very bright long-delayed dancing sprite with distinct horizontal displacement from its parent stroke. The dancing sprite lasted only 60 ms, and the morphology consisted of three fields with two slim dim sprite elements in the first two fields and a very bright large element in the third field, different from other observations where the dancing sprites usually contained multiple elements over a longer time interval, and the sprite shape and brightness in the video field are often similar to the previous fields. The bright sprite was displaced at least 38 km from its parent cloud-to-ground (CG) stroke and occurred over comparatively higher cloud top region. The parent flash of this compact dancing sprite was of positive polarity, with only one return stroke (approximately +24 kA) and obvious continuing current process, and the charge moment change of stroke was small (barely above the threshold for sprite production). All the sprite elements occurred during the continuing current stage, and the bright long-delayed sprite element induced a considerable current pulse. The dancing feature of this sprite may be linked to the electrical charge structure, dynamics and microphysics of parent storm, and the inferred development of parent CG flash was consistent with previous very high-frequency (VHF) observations of lightning in the same region.

  15. An Ion Displacement Membrane Model

    PubMed Central

    Hladky, Stephen B.; Harris, Joseph D.

    1967-01-01

    The usual assumption in treating the diffusion of ions in an electric field has been that the movement of each ion is independent of the movement of the others. The resulting equation for diffusion by a succession of spontaneous jumps has been well stated by Parlin and Eyring. This paper will consider one simple case in which a different assumption is reasonable. Diffusion of monovalent positive ions is considered as a series of jumps from one fixed negative site to another. The sites are assumed to be full (electrical neutrality). Interaction occurs by the displacement of one ion by another. An ion leaves a site if and only if another ion, not necessarily of the same species, attempts to occupy the same site. Flux ratios and net fluxes are given as functions of the electrical potential, concentration ratios, and number of sites encountered in crossing the membrane. Quantitative comparisons with observations of Hodgkin and Keynes are presented. PMID:6048876

  16. Displaced vertices in extended supersymmetric models

    NASA Astrophysics Data System (ADS)

    Hesselbach, S.; Franke, F.; Fraas, H.

    2000-10-01

    In extended supersymmetric models with additional singlet Higgs fields displaced vertices could be observed if the decay width of the next-to-lightest supersymmetric particle becomes very small due to a singlino dominated LSP. We study the supersymmetric parameter space where displaced vertices of the second lightest neutralino exist in the NMSSM and an E6 inspired model. For a mass difference between LSP and NLSP of more than 10 GeV the singlet vacuum expectation value has to be at least of the order of /100 TeV in order to obtain a lightest neutralino with a singlino component large enough for displaced vertices.

  17. Modeling Horizontal GPS Seasonal Signals Caused by Ocean Loading

    NASA Astrophysics Data System (ADS)

    Bartlow, N. M.; Fialko, Y. A.

    2014-12-01

    GPS monuments around the world exhibit seasonal signals in both the horizontal and vertical components with amplitudes on the order of centimeters. For analysis of tectonic signals, researchers typically fit and remove a sine wave with an annual period, and sometimes an additional sine wave with a semiannual period. As interest grows in analyzing smaller, slower signals it becomes more important to correct for these seasonal signals accurately. It is well established that the vertical component of seasonal GPS signals is largely due to continental water storage cycles (e.g. van Dam et al., GRL, 2001). Horizontal seasonal signals however are not well explained by continental water storage. We examine horizontal seasonal signals across western North America and find that the horizontal component is coherent at very large spatial scales and is in general oriented perpendicular to the nearest coastline, indicating an oceanic origin. Additionally, horizontal and vertical annual signals are out of phase by approximately 2 months indicating different physical origins. Studies of GRACE and ocean bottom pressure data indicate an annual variation of non-steric, non-tidal ocean height with an average amplitude of 1 cm globally (e.g. Ponte et al., GRL, 2007). We use Some Programs for Ocean Tide Loading (SPOTL; Agnew, SIO Technical Report, 2012) to model predicted displacements due to these (non-tidal) ocean loads and find general agreement with observed horizontal GPS seasonal signals. In the future, this may lead to a more accurate way to predict and remove the seasonal component of GPS displacement time-series, leading to better discrimination of the true tectonic signal. Modeling this long wavelength signal also provides a potential opportunity to probe the structure of the Earth.

  18. Horizontal and Vertical Surface Displacements in the Upper Rhine Graben Derived from GNSS and Precise Levelling Data

    NASA Astrophysics Data System (ADS)

    Fuhrmann, T.; Knöpfler, A.; Masson, F.; Mayer, M.; Ulrich, P.; Westerhaus, M.; Zippelt, K.; Heck, B.

    2012-04-01

    At the Geodetic Institute, Karlsruhe Institute of Technology, the Upper Rhine Graben (URG) area is investigated using various geodetic techniques. The recent objective is to gain detailed insight in the horizontal and vertical velocity field of the URG from GNSS and levelling data. In addition, it is planned to integrate InSAR data and to rigorously merge the three geodetic measurement techniques into a combined 3D displacement solution. For the GNSS part, a transnational network called GURN (GNSS Upper Rhine Graben Network) was established in 2008 in close cooperation with the Institute de Physique du Globe de Strasbourg (France). GURN actually consist of more than 80 permanently operating GNSS sites of Germany, France and Switzerland. A continuous database is existing since 2002. The analysis strategy for the determination of horizontal and vertical displacement rates and first results from up to 10 years long GNSS time series will be presented. Besides GNSS, the analysis of precise levelling data enables an accurate determination of vertical displacement rates at levelling benchmarks, if repeated measurements at identical benchmarks are available. The levelling measurements in the URG area were carried out by the ordnance survey of Germany, France and Switzerland along levelling lines. These levelling lines were measured up to five times within the last 100 years. Therefore, at discrete benchmarks a detailed assessment of surface displacements could be carried out. The presentation will compare the results of the two geodetic measurement techniques applied within the research activities in the URG area. As levelling and GNSS are point-wise measurement techniques, the spatial resolution of estimated surface displacements is poor. Therefore, InSAR data is used to fill the gap in the future. A short outlook will point out possibilities and limitations on the combination of GNSS, levelling, and InSAR data for an accurate solution aiming for horizontal and vertical

  19. Vertical displacement threshold sensitivity along the horizontal meridian as a function of stimulus rate, duration, and length

    NASA Technical Reports Server (NTRS)

    Haines, Richard F.; Kiefel, Steven M.

    1988-01-01

    Four independent variables of visual perception during binocular viewing were studied. In 24 observers, the vertical displacement threshold (DT) sensitivity along the horizontal meridian was determined as a function of the rate, duration, and length of the stimulus. It was found that the DT increases with an increased angular separation of the stimulus image from the fovea (i.e., the stimulus must move farther in order to be correctly discriminated as having moved). In addition, it was found that the sensitivity to the stimulus displacement increases with increasing of the stimulus length, duration, and/or angular rate. These findings are related to the design optimization of dynamic attitude displays and symbology for aircraft.

  20. Regression models for estimating coseismic landslide displacement

    USGS Publications Warehouse

    Jibson, R.W.

    2007-01-01

    Newmark's sliding-block model is widely used to estimate coseismic slope performance. Early efforts to develop simple regression models to estimate Newmark displacement were based on analysis of the small number of strong-motion records then available. The current availability of a much larger set of strong-motion records dictates that these regression equations be updated. Regression equations were generated using data derived from a collection of 2270 strong-motion records from 30 worldwide earthquakes. The regression equations predict Newmark displacement in terms of (1) critical acceleration ratio, (2) critical acceleration ratio and earthquake magnitude, (3) Arias intensity and critical acceleration, and (4) Arias intensity and critical acceleration ratio. These equations are well constrained and fit the data well (71% < R2 < 88%), but they have standard deviations of about 0.5 log units, such that the range defined by the mean ?? one standard deviation spans about an order of magnitude. These regression models, therefore, are not recommended for use in site-specific design, but rather for regional-scale seismic landslide hazard mapping or for rapid preliminary screening of sites. ?? 2007 Elsevier B.V. All rights reserved.

  1. Rupture models with dynamically determined breakdown displacement

    USGS Publications Warehouse

    Andrews, D.J.

    2004-01-01

    The critical breakdown displacement, Dc, in which friction drops to its sliding value, can be made dependent on event size by specifying friction to be a function of variables other than slip. Two such friction laws are examined here. The first is designed to achieve accuracy and smoothness in discrete numerical calculations. Consistent resolution throughout an evolving rupture is achieved by specifying friction as a function of elapsed time after peak stress is reached. Such a time-weakening model produces Dc and fracture energy proportional to the square root of distance rupture has propagated in the case of uniform stress drop. The second friction law is more physically motivated. Energy loss in a damage zone outside the slip zone has the effect of increasing Dc and limiting peak slip velocity (Andrews, 1976). This article demonstrates a converse effect, that artificially limiting slip velocity on a fault in an elastic medium has a toughening effect, increasing fracture energy and Dc proportionally to rupture propagation distance in the case of uniform stress drop. Both the time-weakening and the velocity-toughening models can be used in calculations with heterogeneous stress drop.

  2. Shallow water model for horizontal centrifugal casting

    NASA Astrophysics Data System (ADS)

    Boháček, J.; Kharicha, A.; Ludwig, A.; Wu, M.

    2012-07-01

    A numerical model was proposed to simulate the solidification process of an outer shell of work roll made by the horizontal centrifugal casting technique. Shallow water model was adopted to solve the 2D average flow dynamics of melt spreading and the average temperature distribution inside the centrifugal casting mould by considering the centrifugal force, Coriolis force, viscous force due to zero velocity on the mould wall, gravity, and energy transport by the flow. Additionally, a 1D sub-model was implemented to consider the heat transfer in the radial direction from the solidifying shell to the mould. The solidification front was tracked by fulfilling the Stefan condition. Radiative and convective heat losses were included from both, the free liquid surface and the outer wall of the mould. Several cases were simulated with the following assumed initial conditions: constant height of the liquid metal (10, 20, and 30 mm), uniform temperature of the free liquid surface (1755 K). The simulation results have shown that while the solidification front remained rather flat, the free surface was disturbed by waves. The amplitude of waves increased with the liquid height. Free surface waves diminished as the solidification proceeded.

  3. Computational modeling of the nonlinear stochastic dynamics of horizontal drillstrings

    NASA Astrophysics Data System (ADS)

    Cunha, Americo; Soize, Christian; Sampaio, Rubens

    2015-11-01

    This work intends to analyze the nonlinear stochastic dynamics of drillstrings in horizontal configuration. For this purpose, it considers a beam theory, with effects of rotatory inertia and shear deformation, which is capable of reproducing the large displacements that the beam undergoes. The friction and shock effects, due to beam/borehole wall transversal impacts, as well as the force and torque induced by bit-rock interaction, are also considered in the model. Uncertainties of bit-rock interaction model are taken into account using a parametric probabilistic approach. Numerical simulations have shown that the mechanical system of interest has a very rich nonlinear stochastic dynamics, which generate phenomena such as bit-bounce, stick-slip, and transverse impacts. A study aiming to maximize the drilling process efficiency, varying drillstring velocities of translation and rotation is presented. Also, the work presents the definition and solution of two optimizations problems, one deterministic and one robust, where the objective is to maximize drillstring rate of penetration into the soil respecting its structural limits.

  4. Displacement Parameter Inversion for a Novel Electromagnetic Underground Displacement Sensor

    PubMed Central

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named “EELA forward modeling-approximate inversion method”. Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0–100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  5. Displacement parameter inversion for a novel electromagnetic underground displacement sensor.

    PubMed

    Shentu, Nanying; Li, Qing; Li, Xiong; Tong, Renyuan; Shentu, Nankai; Jiang, Guoqing; Qiu, Guohua

    2014-01-01

    Underground displacement monitoring is an effective method to explore deep into rock and soil masses for execution of subsurface displacement measurements. It is not only an important means of geological hazards prediction and forecasting, but also a forefront, hot and sophisticated subject in current geological disaster monitoring. In previous research, the authors had designed a novel electromagnetic underground horizontal displacement sensor (called the H-type sensor) by combining basic electromagnetic induction principles with modern sensing techniques and established a mutual voltage measurement theoretical model called the Equation-based Equivalent Loop Approach (EELA). Based on that work, this paper presents an underground displacement inversion approach named "EELA forward modeling-approximate inversion method". Combining the EELA forward simulation approach with the approximate optimization inversion theory, it can deduce the underground horizontal displacement through parameter inversion of the H-type sensor. Comprehensive and comparative studies have been conducted between the experimentally measured and theoretically inversed values of horizontal displacement under counterpart conditions. The results show when the measured horizontal displacements are in the 0-100 mm range, the horizontal displacement inversion discrepancy is generally tested to be less than 3 mm under varied tilt angles and initial axial distances conditions, which indicates that our proposed parameter inversion method can predict underground horizontal displacement measurements effectively and robustly for the H-type sensor and the technique is applicable for practical geo-engineering applications. PMID:24858960

  6. Analytical Modeling for the Grating Eddy Current Displacement Sensors

    NASA Astrophysics Data System (ADS)

    Lv, Chunfeng; Tao, Wei; Lei, Huaming; Jiang, Yingying; Zhao, Hui

    2015-02-01

    As a new type of displacement sensor, grating eddy current displacement sensor (GECDS) combines traditional eddy current sensors and grating structure in one. The GECDS performs a wide range displacement measurement without precision reduction. This paper proposes an analytical modeling approach for the GECDS. The solution model is established in the Cartesian coordinate system, and the solving domain is limited to finite extents by using the truncated region eigenfunction expansion method. Based on the second order vector potential, expressions for the electromagnetic field as well as coil impedance related to the displacement can be expressed in closed-form. Theoretical results are then confirmed by experiments, which prove the suitability and effectiveness of the analytical modeling approach.

  7. A novel approach to modeling unstable EOR displacements. Final report

    SciTech Connect

    Peters, E.J.

    1994-04-01

    Most enhanced oil recovery schemes involve the displacement of a more dense and more viscous oil by a less dense and less viscous fluid in a heterogeneous porous medium. The interaction of heterogeneity with the several competing forces, namely, viscous, capillary, gravitational, and dispersive forces, can conspire to make the displacements unstable and difficult to model and to predict. The objective of this research was to develop a systematic methodology for modeling unstable fluid displacements in heterogeneous media. Flow visualization experiments were conducted using X-ray computed tomography imaging and a video imaging workstation to gain insights into the dynamics of unstable displacements, acquire detailed quantitative experimental image data for calibrating numerical models of unstable displacements, and image and characterize heterogeneities in laboratory cores geostatistically. High-resolution numerical models modified for use on vector-architecture supercomputers were used to replicate the image data. Geostatistical models of reservoir heterogeneity were incorporated in order to study the interaction of hydrodynamic instability and heterogeneity in reservoir displacements. Finally, a systematic methodology for matching the experimental data with the numerical models and scaling the laboratory results to other systems were developed. The result is a new method for predicting the performance of unstable EOR displacements in the field based on small-scale displacements in the laboratory. The methodology is general and can be applied to forecast the performance of most processes that involve fluid flow and transport in porous media. Therefore, this research should be of interest to those involved in forecasting the performance of enhanced oil recovery processes and the spreading of contaminants in heterogeneous aquifers.

  8. HORSMIC. Horizontal Salt Solution Mining Model

    SciTech Connect

    Russo, A.J.

    1994-01-01

    The code HORSMIC was written to solve the problem of calculating the shape of hydrocarbon (gas or liquid) storage caverns formed by solution mining in bedded salt formations. In the past many storage caverns have been formed by vertically drilling into salt dome formations and solution mining large-aspect-ratio, vertically axisymmetric caverns. This approach is generally not satisfactory for shallow salt beds because it would result in geomechanically-unstable, pancake-shaped caverns. In order to produce a high aspect ratio cavern in the horizontal direction a more complicated strategy must be employed. This code was developed to implement such a strategy, and can be used to estimate the shape of the cavern produced by a prescribed leaching schedule. Multiple trials can then be used to investigate the effects of various pipe hole configurations in order to optimize over the cavern shape.

  9. Model based estimation of image depth and displacement

    NASA Technical Reports Server (NTRS)

    Damour, Kevin T.

    1992-01-01

    Passive depth and displacement map determinations have become an important part of computer vision processing. Applications that make use of this type of information include autonomous navigation, robotic assembly, image sequence compression, structure identification, and 3-D motion estimation. With the reliance of such systems on visual image characteristics, a need to overcome image degradations, such as random image-capture noise, motion, and quantization effects, is clearly necessary. Many depth and displacement estimation algorithms also introduce additional distortions due to the gradient operations performed on the noisy intensity images. These degradations can limit the accuracy and reliability of the displacement or depth information extracted from such sequences. Recognizing the previously stated conditions, a new method to model and estimate a restored depth or displacement field is presented. Once a model has been established, the field can be filtered using currently established multidimensional algorithms. In particular, the reduced order model Kalman filter (ROMKF), which has been shown to be an effective tool in the reduction of image intensity distortions, was applied to the computed displacement fields. Results of the application of this model show significant improvements on the restored field. Previous attempts at restoring the depth or displacement fields assumed homogeneous characteristics which resulted in the smoothing of discontinuities. In these situations, edges were lost. An adaptive model parameter selection method is provided that maintains sharp edge boundaries in the restored field. This has been successfully applied to images representative of robotic scenarios. In order to accommodate image sequences, the standard 2-D ROMKF model is extended into 3-D by the incorporation of a deterministic component based on previously restored fields. The inclusion of past depth and displacement fields allows a means of incorporating the temporal

  10. The role of finite displacements in vocal fold modeling.

    PubMed

    Chang, Siyuan; Tian, Fang-Bao; Luo, Haoxiang; Doyle, James F; Rousseau, Bernard

    2013-11-01

    Human vocal folds experience flow-induced vibrations during phonation. In previous computational models, the vocal fold dynamics has been treated with linear elasticity theory in which both the strain and the displacement of the tissue are assumed to be infinitesimal (referred to as model I). The effect of the nonlinear strain, or geometric nonlinearity, caused by finite displacements is yet not clear. In this work, a two-dimensional model is used to study the effect of geometric nonlinearity (referred to as model II) on the vocal fold and the airflow. The result shows that even though the deformation is under 1 mm, i.e., less than 10% of the size of the vocal fold, the geometric nonlinear effect is still significant. Specifically, model I underpredicts the gap width, the flow rate, and the impact stress on the medial surfaces as compared to model II. The study further shows that the differences are caused by the contact mechanics and, more importantly, the fluid-structure interaction that magnifies the error from the small-displacement assumption. The results suggest that using the large-displacement formulation in a computational model would be more appropriate for accurate simulations of the vocal fold dynamics. PMID:24008392

  11. A heat transfer model of a horizontal ground heat exchanger

    NASA Astrophysics Data System (ADS)

    Mironov, R. E.; Shtern, Yu. I.; Shtern, M. Yu.; Rogachev, M. S.

    2016-04-01

    Ground-source heat pumps are gaining popularity in Eastern Europe, especially those which are using the horizontal ground heat exchanger (GHX). Due to the difficulty of accessing GHX after the installation, materials and the quality of the installation must satisfy the very high requirements. An inaccurate calculation of GHX can be the reason of a scarcity of heat power in a crucial moment. So far, there isn't any appropriate mathematical description of the horizontal GHX which takes into account the mutual influence of GHX pipes on each other. To solve this problem we used the temperature wave approach. As a result, a mathematical model which describes the dependence of the heat transfer rate per unit length of the horizontal GHX pipe on the thermal properties of soil, operating time of GHX and the distance between pipes was obtained. Using this model, heat transfer rates per unit length of a horizontal GHX were plotted as functions of the distance between pipes and operating time. The modeling shows that heat transfer rates decreases rapidly with the distance between pipes lower then 2 meters. After the launch of heat pump, heat power of GHX is reduced during the first 20 - 30 days and get steady after that. The obtained results correlate with experimental data. Therefore the proposed mathematical model can be used to design a horizontal GHX with the optimal characteristics, and predict its capability during operation.

  12. Horizontal density compensation in ocean general circulation models

    NASA Astrophysics Data System (ADS)

    Koch, Andrey O.; Helber, Robert W.; Richman, James G.; Barron, Charlie N.

    2013-04-01

    Density compensation is the condition where temperature (T) and salinity (S) gradients counteract in their effect on density. Open ocean observations with SeaSoar tows and recent glider observations in the Gulf of Mexico reported in the scientific literature suggest that horizontal gradients in the surface mixed layer tend to be strongly density compensated over a range of spatial scales while in seasonal thermocline and deeper layers T,S-fronts are only partially compensated or uncompensated. We assess the capability of ocean general circulation models (OGCM) to develop horizontal density compensation as observed in the upper ocean. The physics required to evolve the initial density compensated mixed layer toward the partially compensated conditions of the thermocline is tested. Idealistic scenarios with horizontal, partially compensated density fronts in the mixed layer are examined in submesoscale-resolved run-down simulations on Hybrid Coordinate Ocean Model (HYCOM). Simulations with no atmospheric forcing show that initial Density compensation does not change substantially experiencing only minor decrease with time simultaneously with the restratification of the mixed layer by submesoscale eddies. Submesoscale fronts tend to be more compensated than mesoscale fronts. A sensitivity analysis shows that the density compensation of submesoscale fronts is particularly sensitive to the horizontal diffusion rate. Simulations with wind forcing exhibit destruction of initial density compensation due to ageostrophic frontogenesis which is confirmed by recent glider observations in the Gulf of Mexico. The lack of the model skill to develop and maintain compensated thermohaline variability is attributed to the T, S horizontal diffusion parameterization used in HYCOM and generally in modern OGCMs: it is decoupled from vertical diffusion and T and S diffusion is horizontally identical. Our findings suggest that OGCM's skill to develop compensated thermohaline variability

  13. Force-displacement model for analysis of pulsed-GMAW

    NASA Astrophysics Data System (ADS)

    Arif, Nabeel; Lee, Jae Hak; Yoo, Choong Don

    2009-02-01

    A force-displacement model (FDM) is introduced in this work to analyse pulsed gas metal arc welding (GMAW). The drop detaching criterion is established based on the displacement of the pendant drop instead of the previous force balance criterion. The displacement of the drop is calculated by integrating the acceleration of the drop, and the force exerted on the drop is predicted using the modified force balance model coupled with wire melting. When the peak current, base current and time of pulsed-GMAW are given, the peak time for the one-drop one-pulse condition is determined using the FDM. While the peak current has the most significant effect on drop detachment, the initial drop mass prior to the peak time also influences the drop transfer. The FDM is applied to the dc as well as pulsed-GMAW, and the calculated results show good agreement with the experimental data.

  14. Effects of vertical shear in modelling horizontal oceanic dispersion

    NASA Astrophysics Data System (ADS)

    Lanotte, A. S.; Corrado, R.; Palatella, L.; Pizzigalli, C.; Schipa, I.; Santoleri, R.

    2016-02-01

    The effect of vertical shear on the horizontal dispersion properties of passive tracer particles on the continental shelf of the South Mediterranean is investigated by means of observation and model data. In situ current measurements reveal that vertical gradients of horizontal velocities in the upper mixing layer decorrelate quite fast ( ˜ 1 day), whereas an eddy-permitting ocean model, such as the Mediterranean Forecasting System, tends to overestimate such decorrelation time because of finite resolution effects. Horizontal dispersion, simulated by the Mediterranean sea Forecasting System, is mostly affected by: (1) unresolved scale motions, and mesoscale motions that are largely smoothed out at scales close to the grid spacing; (2) poorly resolved time variability in the profiles of the horizontal velocities in the upper layer. For the case study we have analysed, we show that a suitable use of deterministic kinematic parametrizations is helpful to implement realistic statistical features of tracer dispersion in two and three dimensions. The approach here suggested provides a functional tool to control the horizontal spreading of small organisms or substance concentrations, and is thus relevant for marine biology, pollutant dispersion as well as oil spill applications.

  15. Dynamic modeling of the neck muscles during horizontal head movement.

    PubMed

    Haapala, Stephenie A; Enderle, John D

    2002-01-01

    This paper presents modeling and simulation of superficial neck muscle movement in the horizontal plane (yaw). The parametric muscle model was constructed using Pro/Engineer 2000i Student Edition, Parametric Technologies Corp, and simulated using Pro/Mechanica. Pennation angles, force-tension, force-generation and rate of muscle activation data were obtained from anatomic and physiological studies. Saccadic eye movement models developed by G. Alexander Korentis and John Enderle also provided the basis for this model. PMID:12085608

  16. The subtraction of mutually displaced Gaussian Schell-model beams

    NASA Astrophysics Data System (ADS)

    de Sande, J. Carlos G.; Santarsiero, Massimo; Piquero, Gemma; Gori, Franco

    2015-12-01

    Using recently derived results about the difference of two cross-spectral densities, we consider a source whose correlation function is the difference of two mutually displaced Gaussian Schell-model cross-spectral densities. We examine the main features of this new cross-spectral density in terms of coherence and intensity distribution, both across the source plane and after free propagation.

  17. EXAMINATION OF MODEL PREDICTIONS AT DIFFERENT HORIZONTAL GRID RESOLUTIONS

    EPA Science Inventory

    While fluctuations in meteorological and air quality variables occur on a continuum of spatial scales, the horizontal grid spacing of coupled meteorological and photochemical models sets a lower limit on the spatial scales that they can resolve. However, both computational costs ...

  18. Solar UV geometric conversion factors: horizontal plane to cylinder model.

    PubMed

    Pope, Stanley J; Godar, Dianne E

    2010-01-01

    Most solar UV measurements are relative to the horizontal plane. However, problems arise when one uses those UV measurements to perform risk or benefit assessments because they do not yield the actual doses people get while they are outdoors. To better estimate the UV doses people actually get while outdoors, scientists need geometric conversion factors (GCF) that change horizontal plane irradiances to average irradiances on the human body. Here we describe a simple geometric method that changes unweighted, erythemally weighted and previtamin D(3)-weighted UV irradiances on the horizontal plane to full cylinder and semicylinder irradiances. Scientists can use the full cylinder model to represent the complete human body, while they can use the semicylinder model to represent the face, shoulders, tops of hands and feet. We present daily, monthly and seasonally calculated averages of the GCF for these cylinder models every 5 degrees from 20 to 70 degrees N so that scientists can now get realistic UV doses for people who are outdoors doing a variety of different activities. The GCF show that people actually get less than half their annual erythemally weighted, and consequently half their previtamin D(3)-weighted, UV doses relative to the horizontal plane. Thus, scientists can now perform realistic UV risk and benefit assessments. PMID:20059727

  19. A thermal modelling of displacement cascades in uranium dioxide

    NASA Astrophysics Data System (ADS)

    Martin, G.; Garcia, P.; Sabathier, C.; Devynck, F.; Krack, M.; Maillard, S.

    2014-05-01

    The space and time dependent temperature distribution was studied in uranium dioxide during displacement cascades simulated by classical molecular dynamics (MD). The energy for each simulated radiation event ranged between 0.2 keV and 20 keV in cells at initial temperatures of 700 K or 1400 K. Spheres into which atomic velocities were rescaled (thermal spikes) have also been simulated by MD to simulate the thermal excitation induced by displacement cascades. Equipartition of energy was shown to occur in displacement cascades, half of the kinetic energy of the primary knock-on atom being converted after a few tenths of picoseconds into potential energy. The kinetic and potential parts of the system energy are however subjected to little variations during dedicated thermal spike simulations. This is probably due to the velocity rescaling process, which impacts a large number of atoms in this case and would drive the system away from a dynamical equilibrium. This result makes questionable MD simulations of thermal spikes carried out up to now (early 2014). The thermal history of cascades was compared to the heat equation solution of a punctual thermal excitation in UO2. The maximum volume brought to a temperature above the melting temperature during the simulated cascade events is well reproduced by this simple model. This volume eventually constitutes a relevant estimate of the volume affected by a displacement cascade in UO2. This definition of the cascade volume could also make sense in other materials, like iron.

  20. The structure of horizontal-branch models. I - The zero-age horizontal branch

    NASA Technical Reports Server (NTRS)

    Dorman, Ben

    1992-01-01

    A detailed study of the structure of zero-age horizontal-branch (ZAHB) models is studied in order to show how the hydrostatic structure of these models changes with the input parameters and determines the H-R diagram location of a given model. The properties of composite polytropes on the homology-invariant (U,V)-plane are demonstrated. A variety of test models and sequences were constructed to elucidate the underlying factors that give rise to the wide variation in HB model properties with composition. The roles of the CNO elements as nuclear catalysts and of the envelope sources, as well as the envelope helium abundance are reexamined. It is found that, for stars of a fixed range of mass arriving on the HB, the stellar distribution is determined mainly by CNO for low metallicities (Fe/H of less than about -1), but mainly by opacity sources for high metallicities. The value of Fe/H where CNO ceases to dominate depends significantly on the adopted opacity and will decrease if and when opacity estimates are revised upward.

  1. A Simple Model of Cirrus Horizontal Inhomogeneity and Cloud Fraction

    NASA Technical Reports Server (NTRS)

    Smith, Samantha A.; DelGenio, Anthony D.

    1998-01-01

    A simple model of horizontal inhomogeneity and cloud fraction in cirrus clouds has been formulated on the basis that all internal horizontal inhomogeneity in the ice mixing ratio is due to variations in the cloud depth, which are assumed to be Gaussian. The use of such a model was justified by the observed relationship between the normalized variability of the ice water mixing ratio (and extinction) and the normalized variability of cloud depth. Using radar cloud depth data as input, the model reproduced well the in-cloud ice water mixing ratio histograms obtained from horizontal runs during the FIRE2 cirrus campaign. For totally overcast cases the histograms were almost Gaussian, but changed as cloud fraction decreased to exponential distributions which peaked at the lowest nonzero ice value for cloud fractions below 90%. Cloud fractions predicted by the model were always within 28% of the observed value. The predicted average ice water mixing ratios were within 34% of the observed values. This model could be used in a GCM to produce the ice mixing ratio probability distribution function and to estimate cloud fraction. It only requires basic meteorological parameters, the depth of the saturated layer and the standard deviation of cloud depth as input.

  2. An accurate elasto-plastic frictional tangential force displacement model for granular-flow simulations: Displacement-driven formulation

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Vu-Quoc, Loc

    2007-07-01

    We present in this paper the displacement-driven version of a tangential force-displacement (TFD) model that accounts for both elastic and plastic deformations together with interfacial friction occurring in collisions of spherical particles. This elasto-plastic frictional TFD model, with its force-driven version presented in [L. Vu-Quoc, L. Lesburg, X. Zhang. An accurate tangential force-displacement model for granular-flow simulations: contacting spheres with plastic deformation, force-driven formulation, Journal of Computational Physics 196(1) (2004) 298-326], is consistent with the elasto-plastic frictional normal force-displacement (NFD) model presented in [L. Vu-Quoc, X. Zhang. An elasto-plastic contact force-displacement model in the normal direction: displacement-driven version, Proceedings of the Royal Society of London, Series A 455 (1991) 4013-4044]. Both the NFD model and the present TFD model are based on the concept of additive decomposition of the radius of contact area into an elastic part and a plastic part. The effect of permanent indentation after impact is represented by a correction to the radius of curvature. The effect of material softening due to plastic flow is represented by a correction to the elastic moduli. The proposed TFD model is accurate, and is validated against nonlinear finite element analyses involving plastic flows in both the loading and unloading conditions. The proposed consistent displacement-driven, elasto-plastic NFD and TFD models are designed for implementation in computer codes using the discrete-element method (DEM) for granular-flow simulations. The model is shown to be accurate and is validated against nonlinear elasto-plastic finite-element analysis.

  3. Modeling of two-hot-arm horizontal thermal actuator

    NASA Astrophysics Data System (ADS)

    Yan, Dong; Khajepour, Amir; Mansour, Raafat

    2003-03-01

    Electrothermal actuators have a very promising future in MEMS applications since they can generate large deflection and force with low actuating voltages and small device areas. In this study, a lumped model of a two-hot-arm horizontal thermal actuator is presented. In order to prove the accuracy of the lumped model, finite element analysis (FEA) and experimental results are provided. The two-hot-arm thermal actuator has been fabricated using the MUMPs process. Both the experimental and FEA results are in good agreement with the results of lumped modeling.

  4. A physical model for measuring thermally-induced block displacements

    NASA Astrophysics Data System (ADS)

    Bakun-Mazor, Dagan; Feldhiem, Aviran; Keissar, Yuval; Hatzor, Yossef H.

    2016-04-01

    A new model for thermally-induced block displacement in discontinuous rock slopes has been recently suggested. The model consists of a discrete block that is separated from the rock mass by a tension crack and rests on an inclined plane. The tension crack is filled with a wedge block or rock fragments. Irreversible block sliding is assumed to develop in response to climatic thermal fluctuations and consequent contraction and expansion of the sliding block material. While a tentative analytical solution for this model is already available, we are exploring here the possibility of obtaining such a permanent, thermally-induced, rock block displacement, under fully controlled conditions at the laboratory, and the sensitivity of the mechanism to geometry, mechanical properties, and temperature fluctuations. A large scale concrete physical model (50x150x60 cm^3) is being examined in a Climate-Controlled Room (CCR). The CCR permits accurate control of ambient temperature from 5 to 45 Celsius degrees. The permanent plastic displacement is being measured using four displacement transducers and a high resolution (29M pixel) visual range camera. A series of thermocouples measure the heating front inside the sliding block, hence thermal diffusivity is evaluated from the measured thermal gradient and heat flow. In order to select the appropriate concrete mixture, the mechanical and thermo-physical properties of concrete samples are determined in the lab. Friction angle and shear stiffness of the sliding interface are determined utilizing a hydraulic, servo-controlled direct shear apparatus. Uniaxial compression tests are performed to determine the uniaxial compressive strength, Young's modulus and Poison's ratio of the intact block material using a stiff triaxial load frame. Thermal conductivity and linear thermal expansion coefficient are determined experimentally using a self-constructed measuring system. Due to the fact that this experiment is still in progress, preliminary

  5. INCAS: an analytical model to describe displacement cascades

    NASA Astrophysics Data System (ADS)

    Jumel, Stéphanie; Claude Van-Duysen, Jean

    2004-07-01

    REVE (REactor for Virtual Experiments) is an international project aimed at developing tools to simulate neutron irradiation effects in Light Water Reactor materials (Fe, Ni or Zr-based alloys). One of the important steps of the project is to characterise the displacement cascades induced by neutrons. Accordingly, the Department of Material Studies of Electricité de France developed an analytical model based on the binary collision approximation. This model, called INCAS (INtegration of CAScades), was devised to be applied on pure elements; however, it can also be used on diluted alloys (reactor pressure vessel steels, etc.) or alloys composed of atoms with close atomic numbers (stainless steels, etc.). INCAS describes displacement cascades by taking into account the nuclear collisions and electronic interactions undergone by the moving atoms. In particular, it enables to determine the mean number of sub-cascades induced by a PKA (depending on its energy) as well as the mean energy dissipated in each of them. The experimental validation of INCAS requires a large effort and could not be carried out in the framework of the study. However, it was verified that INCAS results are in conformity with those obtained from other approaches. As a first application, INCAS was applied to determine the sub-cascade spectrum induced in iron by the neutron spectrum corresponding to the central channel of the High Flux Irradiation Reactor of Oak Ridge National Laboratory.

  6. Modeling averaged displacement fronts in heterogeneous media with multirate mass transfer models

    NASA Astrophysics Data System (ADS)

    Neuweiler, Insa; Heiss, Veronica; Tecklenburg, Jan

    2013-04-01

    of the heterogeneous structure has a crucial influence on the front morphology. For these numerical simulations we compare the averaged fluid distribution to an upscaled one-dimensional model. In the upscaled model, the immobilization of displaced fluid behind the front is captured by a double continuum approach, where the immobilized fluid is considered an immobile continuum. The size of the immobile continuum changes with time. The flow is modeled in the mobile continuum with a multi-rate mass-transfer term to capture exchange with the immobile domain. The rate coefficients for the mass transfer have to be estimated from the size distribution of immobilized fluid clusters. It is demonstrated that such a simplified model can describe the displacement well, if the front morphology is not too complex.

  7. Wind-Tunnel Tests of a 1/5-Scale Semispan Model of the Republic XF-12 Horizontal Tail Surface

    NASA Technical Reports Server (NTRS)

    Denaci, H. G.

    1945-01-01

    Wind-tunnel tests of a 1/5-scale semispan model of the Republic XF-12 horizontal tail surface equipped with an internally balanced elevator were conducted in the 6- by 6-foot test section of the Langley stability tunnel. The tests included measurements of the aerodynamic characteristics of the horizontal tail with and without a beveled trailing edge and also included measurements of the tab characteristics. The variation of the aerodynamic characteristics with boundary-layer conditions and leakage in the internal-balance chambers, measurements of the boundary-layer displacement thickness near the elevator hinge axis, and pressure distributions at the mean geometric chord were also obtained. The results showed that the hinge-moment characteristics of the elevator were critical to boundary-layer conditions and internal-balance leakage. Increasing the boundary-layer displacement thickness by use of roughness strips reduced the rate of change of elevator hinge moments with tab deflection by about 20 percent. The present horizontal tail appears to be unsatisfactory for longitudinal stability with power on, however, an increase in horizontal-tail lift effectiveness should correct this difficulty. The maneuvering stick force per unit acceleration will be extremely critical to minor variations of the elevator hinge moments if the elevator is linked directly to the stick.

  8. Testing the Beat Frequency Model of Horizontal Branch Qpos

    NASA Astrophysics Data System (ADS)

    Hertz, Paul

    The beat frequency modulated accretion (BFMA) model requires strong correlations in the horizontal branch quasiperiodic oscillations (HBO) and low frequency noise (LFN) amplitudes on time scales <1 s as they are both carried by the same accreting clumps. But such correlations have not been observed on time scales <8 s. With RXTE individual HBOs will be detectable in GX5-1 at the 1-2 sigma level. Using an optimal filter we will measure the phase coherence, strength, and clustering length of individual HBOs and the overall shot rate. We will test for the correlations between HBO and LFN amplitude predicted by the BFMA model and constrain some of the free observable parameters in the model. Any HBO model must account for these properties.

  9. Simplified aeroelastic modeling of horizontal axis wind turbines

    NASA Astrophysics Data System (ADS)

    Wendell, J. H.

    1982-09-01

    Certain aspects of the aeroelastic modeling and behavior of the horizontal axis wind turbine (HAWT) are examined. Two simple three degree of freedom models are described in this report, and tools are developed which allow other simple models to be derived. The first simple model developed is an equivalent hinge model to study the flap-lag-torsion aeroelastic stability of an isolated rotor blade. The model includes nonlinear effects, preconing, and noncoincident elastic axis, center of gravity, and aerodynamic center. A stability study is presented which examines the influence of key parameters on aeroelastic stability. Next, two general tools are developed to study the aeroelastic stability and response of a teetering rotor coupled to a flexible tower. The first of these tools is an aeroelastic model of a two-bladed rotor on a general flexible support. The second general tool is a harmonic balance solution method for the resulting second order system with periodic coefficients. The second simple model developed is a rotor-tower model which serves to demonstrate the general tools. This model includes nacelle yawing, nacelle pitching, and rotor teetering. Transient response time histories are calculated and compared to a similar model in the literature. Agreement between the two is very good, especially considering how few harmonics are used. Finally, a stability study is presented which examines the effects of support stiffness and damping, inflow angle, and preconing.

  10. Simplified aeroelastic modeling of horizontal axis wind turbines

    NASA Technical Reports Server (NTRS)

    Wendell, J. H.

    1982-01-01

    Certain aspects of the aeroelastic modeling and behavior of the horizontal axis wind turbine (HAWT) are examined. Two simple three degree of freedom models are described in this report, and tools are developed which allow other simple models to be derived. The first simple model developed is an equivalent hinge model to study the flap-lag-torsion aeroelastic stability of an isolated rotor blade. The model includes nonlinear effects, preconing, and noncoincident elastic axis, center of gravity, and aerodynamic center. A stability study is presented which examines the influence of key parameters on aeroelastic stability. Next, two general tools are developed to study the aeroelastic stability and response of a teetering rotor coupled to a flexible tower. The first of these tools is an aeroelastic model of a two-bladed rotor on a general flexible support. The second general tool is a harmonic balance solution method for the resulting second order system with periodic coefficients. The second simple model developed is a rotor-tower model which serves to demonstrate the general tools. This model includes nacelle yawing, nacelle pitching, and rotor teetering. Transient response time histories are calculated and compared to a similar model in the literature. Agreement between the two is very good, especially considering how few harmonics are used. Finally, a stability study is presented which examines the effects of support stiffness and damping, inflow angle, and preconing.

  11. Modelling of horizontal centrifugal casting of work roll

    NASA Astrophysics Data System (ADS)

    Xu, Zhian; Song, Nannan; Tol, Rob Val; Luan, Yikun; Li, Dianzhong

    2012-07-01

    A numerical model to simulate horizontal centrifugal roll castings is presented in this paper. In order to simulate the flow fluid and solidification of horizontal centrifugal roll casting correctly, the model uses a body fitted mesh technique to represent the geometry. This new method maps a plate layer mesh to a circular mesh. The smooth body fitted mesh method gives more accurate calculation results for cylindrical geometries. A velocity depending on the angular velocity and inner radius of the mould is set up as a velocity boundary condition. The fluid flow coupled with heat transfer and solidification in a rapidly rotating roll is simulated. A gravity free falling method is applied as a pouring condition. A moveable pouring system is also used in the simulations. High speed steel is used to produce the work roll. Two different gating positions and a moveable gating system are simulated in this paper. Results show that the position of pouring system has a significant influence on the temperature distribution. The temperature distribution at a fixed central pouring system is more favourable than the distribution from a side pouring system. A moving gating system method is a better way to obtain a uniform temperature field in centrifugal casting and offers an alternative for existing techniques.

  12. Global horizontal irradiance clear sky models : implementation and analysis.

    SciTech Connect

    Stein, Joshua S.; Hansen, Clifford W.; Reno, Matthew J.

    2012-03-01

    Clear sky models estimate the terrestrial solar radiation under a cloudless sky as a function of the solar elevation angle, site altitude, aerosol concentration, water vapor, and various atmospheric conditions. This report provides an overview of a number of global horizontal irradiance (GHI) clear sky models from very simple to complex. Validation of clear-sky models requires comparison of model results to measured irradiance during clear-sky periods. To facilitate validation, we present a new algorithm for automatically identifying clear-sky periods in a time series of GHI measurements. We evaluate the performance of selected clear-sky models using measured data from 30 different sites, totaling about 300 site-years of data. We analyze the variation of these errors across time and location. In terms of error averaged over all locations and times, we found that complex models that correctly account for all the atmospheric parameters are slightly more accurate than other models, but, primarily at low elevations, comparable accuracy can be obtained from some simpler models. However, simpler models often exhibit errors that vary with time of day and season, whereas the errors for complex models vary less over time.

  13. A model approach to assess diaphragmatic volume displacement.

    PubMed

    Petroll, W M; Knight, H; Rochester, D F

    1990-12-01

    Diaphragmatic volume displacement (Vdi) is calculated from two models using measurements obtained from anteroposterior fluoroscopic images of supine anesthetized dogs. In model 1, diaphragmatic descent was treated as if it were a "piston in a cylinder." In contrast, model 2 incorporated thoracic configuration as well as inspiratory changes in rib cage diameter and diaphragm shape. In one dog, a computerized tomography reconstruction of Vdi was compared with Vdi calculated using the models. Vdi calculated from model 2 lay within 11% of the computerized tomographic value, whereas Vdi based on model 1 was 30% larger. In seven animals, radiopaque markers were sewn to the right costal diaphragm. Digitized fluoroscopic images were used to measure intermarker distance, an index of muscle shortening. For four tidal breaths per dog, in model 2 Vdi averaged 49 +/- 18% of tidal volume and was weakly correlated with costal diaphragm muscle shortening (R = 0.74). It is concluded that Vdi can be estimated from linear dimensions in the coronal plane, provided that inspiratory changes in rib cage diameter and diaphragmatic shape change are taken into account. PMID:2077014

  14. Research on Joint Parameter Inversion for an Integrated Underground Displacement 3D Measuring Sensor

    PubMed Central

    Shentu, Nanying; Qiu, Guohua; Li, Qing; Tong, Renyuan; Shentu, Nankai; Wang, Yanjie

    2015-01-01

    Underground displacement monitoring is a key means to monitor and evaluate geological disasters and geotechnical projects. There exist few practical instruments able to monitor subsurface horizontal and vertical displacements simultaneously due to monitoring invisibility and complexity. A novel underground displacement 3D measuring sensor had been proposed in our previous studies, and great efforts have been taken in the basic theoretical research of underground displacement sensing and measuring characteristics by virtue of modeling, simulation and experiments. This paper presents an innovative underground displacement joint inversion method by mixing a specific forward modeling approach with an approximate optimization inversion procedure. It can realize a joint inversion of underground horizontal displacement and vertical displacement for the proposed 3D sensor. Comparative studies have been conducted between the measured and inversed parameters of underground horizontal and vertical displacements under a variety of experimental and inverse conditions. The results showed that when experimentally measured horizontal displacements and vertical displacements are both varied within 0 ~ 30 mm, horizontal displacement and vertical displacement inversion discrepancies are generally less than 3 mm and 1 mm, respectively, under three kinds of simulated underground displacement monitoring circumstances. This implies that our proposed underground displacement joint inversion method is robust and efficient to predict the measuring values of underground horizontal and vertical displacements for the proposed sensor. PMID:25871714

  15. Horizontal shear zones: physical modeling of formation and structure

    NASA Astrophysics Data System (ADS)

    Bokun, A. N.

    2009-11-01

    On examples of ductile viscous materials (pastes), which demonstrated the deformational type of coagulation behavior and the reproduced zones of the horizontal shear of a brittle fracture, ductile flow, and intermediate types. The formation of coagulation agglomerates appeared well organized, both in terms of time and structurally. The found systems of fractures revealed a sequential course of the deformation process and the contribution of each system in the total structural transformation was established. By virtue of rheological analysis of coagulation structures, the basic parameters (yield strength, viscosity), and their input into the model of the deformational response (brittle, ductile), were determined. The substantial composition and its deformational properties of the material under question appeared to dictate the structure of shear zones and their general mutual organization. The rheological analysis of coagulation clusters of model materials allowed for the justified interpretation of experimental data to regulate deformation processes effectively and predict their results.

  16. A GLE multi-block model for the evaluation of seismic displacements of slopes

    SciTech Connect

    Bandini, V.; Cascone, E.; Biondi, G.

    2008-07-08

    The paper describes a multi-block displacement model for the evaluation of seismic permanent displacements of natural slopes with slip surface of general shape. A rigorous limit equilibrium method of stability analysis is considered and an application to an ideal clay slope is presented including the effect of excess pore pressure build-up on the displacement response.

  17. Horizontal gene transfer in eukaryotes: The weak-link model

    PubMed Central

    Huang, Jinling

    2013-01-01

    The significance of horizontal gene transfer (HGT) in eukaryotic evolution remains controversial. Although many eukaryotic genes are of bacterial origin, they are often interpreted as being derived from mitochondria or plastids. Because of their fixed gene pool and gene loss, however, mitochondria and plastids alone cannot adequately explain the presence of all, or even the majority, of bacterial genes in eukaryotes. Available data indicate that no insurmountable barrier to HGT exists, even in complex multicellular eukaryotes. In addition, the discovery of both recent and ancient HGT events in all major eukaryotic groups suggests that HGT has been a regular occurrence throughout the history of eukaryotic evolution. A model of HGT is proposed that suggests both unicellular and early developmental stages as likely entry points for foreign genes into multicellular eukaryotes. PMID:24037739

  18. Modelling coseismic displacements during the 1997 Umbria-Marche earthquake (central Italy)

    NASA Astrophysics Data System (ADS)

    Hunstad, Ingrid; Anzidei, Marco; Cocco, Massimo; Baldi, Paolo; Galvani, Alessandro; Pesci, Arianna

    1999-11-01

    We propose a dislocation model for the two normal faulting earthquakes that struck the central Apennines (Umbria-Marche, Italy) on 1997 September 26 at 00:33 (Mw 5.7) and 09:40 GMT (Mw 6.0). We fit coseismic horizontal and vertical displacements resulting from GPS measurements at several monuments of the IGMI (Istituto Geografico Militare Italiano) by means of a dislocation model in an elastic, homogeneous, isotropic half-space. Our best-fitting model consists of two normal faults whose mechanisms and seismic moments have been taken from CMT solutions; it is consistent with other seismological and geophysical observations. The first fault, which is 6 km long and 7 km wide, ruptured during the 00:33 event with a unilateral rupture towards the SE and an average slip of 27 cm. The second fault is 12 km long and 10 km wide, and ruptured during the 09:40 event with a nearly unilateral rupture towards the NW. Slip distribution on this second fault is non-uniform and is concentrated in its SE portion (maximum slip is 65 cm), where rupture initiated. The 00:33 fault is deeper than the 09:40 one: the top of the first rupture is deeper than 1.7 km the top of the second is 0.6 km deep. In order to interpret the observed epicentral subsidence we have also considered the contributions of two further moderate-magnitude earthquakes that occurred on 1997 October 3 (Mw 5.2) and 6 (Mw 5.4), immediately before the GPS survey, and were located very close to the 09:40 event of September 26. We compare the pattern of vertical displacements resulting from our forward modelling of GPS data with that derived from SAR interferograms: the fit to SAR data is very good, confirming the reliability of the proposed dislocation model.

  19. On Vertically Global, Horizontally Local Models for Astrophysical Disks

    NASA Astrophysics Data System (ADS)

    McNally, Colin P.; Pessah, Martin E.

    2015-10-01

    Disks with a barotropic equilibrium structure, for which the pressure is only a function of the density, rotate on cylinders in the presence of a gravitational potential, so that the angular frequency of such a disk is independent of height. Such disks with barotropic equilibria can be approximately modeled using the shearing box framework, representing a small disk volume with height-independent angular frequency. If the disk is in baroclinic equilibrium, the angular frequency does generally depend on height, and it is thus necessary to go beyond the standard shearing box approach. In this paper, we show that given a global disk model, it is possible to develop approximate models that are local in horizontal planes without an expansion in height with shearing-periodic boundary conditions. We refer to the resulting framework as the vertically global shearing box (VGSB). These models can be non-axisymmetric for globally barotropic equilibria but should be axisymmetric for globally baroclinic equilibria. We provide explicit equations for this VGSB which can be implemented in standard magnetohydrodynamic codes by generalizing the shearing-periodic boundary conditions to allow for a height-dependent angular frequency and shear rate. We also discuss the limitations that result from the radial approximations that are needed in order to impose height-dependent shearing periodic boundary conditions. We illustrate the potential of this framework by studying a vertical shear instability and examining the modes associated with the magnetorotational instability.

  20. Multi-quadric collocation model of horizontal crustal movement

    NASA Astrophysics Data System (ADS)

    Chen, G.; Zeng, A. M.; Ming, F.; Jing, Y. F.

    2015-11-01

    To establish the horizontal crustal movement velocity field of the Chinese mainland, a Hardy multi-quadric fitting model and collocation are usually used, but the kernel function, nodes, and smoothing factor are difficult to determine in the Hardy function interpolation, and in the collocation model the covariance function of the stochastic signal must be carefully constructed. In this paper, a new combined estimation method for establishing the velocity field, based on collocation and multi-quadric equation interpolation, is presented. The crustal movement estimation simultaneously takes into consideration an Euler vector as the crustal movement trend and the local distortions as the stochastic signals, and a kernel function of the multi-quadric fitting model substitutes for the covariance function of collocation. The velocities of a set of 1070 reference stations were obtained from the Crustal Movement Observation Network of China (CMONOC), and the corresponding velocity field established using the new combined estimation method. A total of 85 reference stations were used as check points, and the precision in the north and east directions was 1.25 and 0.80 mm yr-1, respectively. The result obtained by the new method corresponds with the collocation method and multi-quadric interpolation without requiring the covariance equation for the signals.

  1. Atmospheric Climate Model Experiments Performed at Multiple Horizontal Resolutions

    SciTech Connect

    Phillips, T; Bala, G; Gleckler, P; Lobell, D; Mirin, A; Maxwell, R; Rotman, D

    2007-12-21

    This report documents salient features of version 3.3 of the Community Atmosphere Model (CAM3.3) and of three climate simulations in which the resolution of its latitude-longitude grid was systematically increased. For all these simulations of global atmospheric climate during the period 1980-1999, observed monthly ocean surface temperatures and sea ice extents were prescribed according to standard Atmospheric Model Intercomparison Project (AMIP) values. These CAM3.3 resolution experiments served as control runs for subsequent simulations of the climatic effects of agricultural irrigation, the focus of a Laboratory Directed Research and Development (LDRD) project. The CAM3.3 model was able to replicate basic features of the historical climate, although biases in a number of atmospheric variables were evident. Increasing horizontal resolution also generally failed to ameliorate the large-scale errors in most of the climate variables that could be compared with observations. A notable exception was the simulation of precipitation, which incrementally improved with increasing resolution, especially in regions where orography plays a central role in determining the local hydroclimate.

  2. Modeling Progressive Damage Using Local Displacement Discontinuities Within the FEAMAC Multiscale Modeling Framework

    NASA Technical Reports Server (NTRS)

    Ranatunga, Vipul; Bednarcyk, Brett A.; Arnold, Steven M.

    2010-01-01

    A method for performing progressive damage modeling in composite materials and structures based on continuum level interfacial displacement discontinuities is presented. The proposed method enables the exponential evolution of the interfacial compliance, resulting in unloading of the tractions at the interface after delamination or failure occurs. In this paper, the proposed continuum displacement discontinuity model has been used to simulate failure within both isotropic and orthotropic materials efficiently and to explore the possibility of predicting the crack path, therein. Simulation results obtained from Mode-I and Mode-II fracture compare the proposed approach with the cohesive element approach and Virtual Crack Closure Techniques (VCCT) available within the ABAQUS (ABAQUS, Inc.) finite element software. Furthermore, an eccentrically loaded 3-point bend test has been simulated with the displacement discontinuity model, and the resulting crack path prediction has been compared with a prediction based on the extended finite element model (XFEM) approach.

  3. Preview Scheduled Model Predictive Control For Horizontal Axis Wind Turbines

    NASA Astrophysics Data System (ADS)

    Laks, Jason H.

    This research investigates the use of model predictive control (MPC) in application to wind turbine operation from start-up to cut-out. The studies conducted are focused on the design of an MPC controller for a 650˜KW, three-bladed horizontal axis turbine that is in operation at the National Renewable Energy Laboratory's National Wind Technology Center outside of Golden, Colorado. This turbine is at the small end of utility scale turbines, but it provides advanced instrumentation and control capabilities, and there is a good probability that the approach developed in simulation for this thesis, will be field tested on the actual turbine. A contribution of this thesis is a method to combine the use of preview measurements with MPC while also providing regulation of turbine speed and cyclic blade loading. A common MPC technique provides integral-like control to achieve offset-free operation. At the same time in wind turbine applications, multiple studies have developed "feed-forward" controls based on applying a gain to an estimate of the wind speed changes obtained from an observer incorporating a disturbance model. These approaches are based on a technique that can be referred to as disturbance accommodating control (DAC). In this thesis, it is shown that offset-free tracking MPC is equivalent to a DAC approach when the disturbance gain is computed to satisfy a regulator equation. Although the MPC literature has recognized that this approach provides "structurally stable" disturbance rejection and tracking, this step is not typically divorced from the MPC computations repeated each sample hit. The DAC formulation is conceptually simpler, and essentially uncouples regulation considerations from MPC related issues. This thesis provides a self contained proof that the DAC formulation (an observer-controller and appropriate disturbance gain) provides structurally stable regulation.

  4. Disaster Hits Home: A Model of Displaced Family Adjustment after Hurricane Katrina

    ERIC Educational Resources Information Center

    Peek, Lori; Morrissey, Bridget; Marlatt, Holly

    2011-01-01

    The authors explored individual and family adjustment processes among parents (n = 30) and children (n = 55) who were displaced to Colorado after Hurricane Katrina. Drawing on in-depth interviews with 23 families, this article offers an inductive model of displaced family adjustment. Four stages of family adjustment are presented in the model: (a)…

  5. Modelling static 3-D spatial background error covariances - the effect of vertical and horizontal transform order

    NASA Astrophysics Data System (ADS)

    Wlasak, M. A.; Cullen, M. J. P.

    2014-06-01

    A major difference in the formulation of the univariate part of static background error covariance models for use in global operational 4DVAR arises from the order in which the horizontal and vertical transforms are applied. This is because the atmosphere is non-separable with large horizontal scales generally tied to large vertical scales and small horizontal scales tied to small vertical scales. Also horizontal length scales increase dramatically as one enters the stratosphere. A study is presented which evaluates the strengths and weaknesses of each approach with the Met Office Unified Model. It is shown that if the vertical transform is applied as a function of horizontal wavenumber then the horizontal globally-averaged variance and the homogenous, isotropic length scale on each model level for each control variable of the training data is preserved by the covariance model. In addition the wind variance and associated length scales are preserved as the scheme preserves the variances and length scales of horizontal derivatives. If the vertical transform is applied in physical space, it is possible to make it a function of latitude at the cost of not preserving the variances and length scales of the horizontal derivatives. Summer and winter global 4DVAR trials have been run with both background error covariance models. A clear benefit is seen in the fit to observations when the vertical transform is in spectral space and is a function of total horizontal wavenumber.

  6. Longitudinal displacement in viscoelastic arteries: a novel fluid-structure interaction computational model, and experimental validation.

    PubMed

    Bukač, Martina; Čanić, Sunčica

    2013-04-01

    Recent in vivo studies, utilizing ultrasound contour and speckle tracking methods, have identified significant longitudinal displacements of the intima-media complex, and viscoelastic arterial wall properties over a cardiac cycle. Existing computational models that use thin structure approximations of arterial walls have so far been limited to models that capture only radial wall displacements. The purpose of this work is to present a simple fluid-struture interaction (FSI) model and a stable, partitioned numerical scheme, which capture both longitudinal and radial displacements, as well as viscoelastic arterial wall properties. To test the computational model, longitudinal displacement of the common carotid artery and of the stenosed coronary arteries were compared with experimental data found in literature, showing excellent agreement. We found that, unlike radial displacement, longitudinal displacement in stenotic lesions is highly dependent on the stenotic geometry. We also showed that longitudinal displacement in atherosclerotic arteries is smaller than in healthy arteries, which is in line with the recent in vivo measurements that associate plaque burden with reduced total longitudinal wall displacement. This work presents a first step in understanding the role of longitudinal displacement in physiology and pathophysiology of arterial wall mechanics using computer simulations. PMID:23458302

  7. Horizontal drilling technology advances

    SciTech Connect

    Not Available

    1991-03-04

    Horizontal drilling technology is making further advances in the Texas Austin chalk play as such drilling continues to spread in many U.S. land areas. One company has completed a Cretaceous Austin chalk oil well with the longest horizontal well bore in Texas and what at 1 1/6 miles is believed to be the world's longest medium radius horizontal displacement.

  8. ALCAR - A Model for Horizontal R&D Consortia

    SciTech Connect

    Barthold, G.B.; Das, S.K.; Hayden, H.W.

    1999-03-01

    The ALCARTM Consortium was created to develop a low cost, non-heat treatable automotive body sheet alloy. This paper will discuss the management aspects of organizing and running a horizontal consortium for competing companies to cooperate in conducting pre-competitive research and development involving the US Department of Energy, National Laboratories, Universities and industrial consultants.

  9. A complete solution of cartographic displacement based on elastic beams model and Delaunay triangulation

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Guo, Q.; Sun, Y.

    2014-04-01

    In map production and generalization, it is inevitable to arise some spatial conflicts, but the detection and resolution of these spatial conflicts still requires manual operation. It is become a bottleneck hindering the development of automated cartographic generalization. Displacement is the most useful contextual operator that is often used for resolving the conflicts arising between two or more map objects. Automated generalization researches have reported many approaches of displacement including sequential approaches and optimization approaches. As an excellent optimization approach on the basis of energy minimization principles, elastic beams model has been used in resolving displacement problem of roads and buildings for several times. However, to realize a complete displacement solution, techniques of conflict detection and spatial context analysis should be also take into consideration. So we proposed a complete solution of displacement based on the combined use of elastic beams model and constrained Delaunay triangulation (CDT) in this paper. The solution designed as a cyclic and iterative process containing two phases: detection phase and displacement phase. In detection phase, CDT of map is use to detect proximity conflicts, identify spatial relationships and structures, and construct auxiliary structure, so as to support the displacement phase on the basis of elastic beams. In addition, for the improvements of displacement algorithm, a method for adaptive parameters setting and a new iterative strategy are put forward. Finally, we implemented our solution on a testing map generalization platform, and successfully tested it against 2 hand-generated test datasets of roads and buildings respectively.

  10. Horizontal Violence and the Quality and Safety of Patient Care: A Conceptual Model

    PubMed Central

    Purpora, Christina; Blegen, Mary A.

    2012-01-01

    For many years, nurses in international clinical and academic settings have voiced concern about horizontal violence among nurses and its consequences. However, no known framework exists to guide research on the topic to explain these consequences. This paper presents a conceptual model that was developed from four theories to illustrate how the quality and safety of patient care could be affected by horizontal violence. Research is needed to validate the new model and to gather empirical evidence of the consequences of horizontal violence on which to base recommendations for future research, education, and practice. PMID:22655187

  11. Modeling flow into horizontal wells in a Dupuit-Forchheimer model.

    PubMed

    Haitjema, Henk; Kuzin, Sergey; Kelson, Vic; Abrams, Daniel

    2010-01-01

    Horizontal wells or radial collector wells are used in shallow aquifers to enhance water withdrawal rates. Groundwater flow patterns near these wells are three-dimensional (3D), but difficult to represent in a 3D numerical model because of the high degree of grid refinement needed. However, for the purpose of designing water withdrawal systems, it is sufficient to obtain the correct production rate of these wells for a given drawdown. We developed a Cauchy boundary condition along a horizontal well in a Dupuit-Forchheimer model. Such a steady-state 2D model is not only useful for predicting groundwater withdrawal rates but also for capture zone delineation in the context of source water protection. A comparison of our Dupuit-Forchheimer model for a radial collector well with a 3D model yields a nearly exact production rate. Particular attention is given to horizontal wells that extend underneath a river. A comparison of our approach with a 3D solution for this case yields satisfactory results, at least for moderate-to-large river bottom resistances. PMID:20331744

  12. Displacement rate dependence of irradiation creep as predicted by the production bias model

    SciTech Connect

    Woo, C.H.

    1996-04-01

    Recently, it has been shown that the non-swelling component of irradiation creep of austenitic stainless steels is relatively independent of temperature but is sensitive to the displacement rate. An earlier model of Lewthwaite and Mosedale anticipated the sensitivity of displacement rate and attributed it to the flux sensitivity of point defect recombination. The point-defect recombination process does not yield the observed temperature dependence, however, although it does predict an inverse dependence of the creep rate on the square root of the displacement rate that was experimentally observed at relatively low temperatures.

  13. Modeling of a horizontal steam generator for the submerged nuclear power station concept

    SciTech Connect

    Palmrose, D.E.; Herring, J.S.

    1993-05-01

    A submerged nuclear power station has been proposed as an alternative power station with a relatively low environmental impact for use by both industrialized and developing countries. The station would be placed 10 m above the seabed at a depth of 30--100 m and a distance of 10--30 km from shore. The submerged nuclear power station would be manufactured and refueled in a central facility, thus gaining the economies of factoryfabrication and the flexibility of short-lead-time deployment. To minimize the size of the submerged hull, horizontal steam generators are proposed for the primary-to-secondary heat transfer, instead of the more traditional vertical steam generators. The horizontal steam generators for SNPS would be similar in design to the horizontal steam generators used in the N-Reactors except the tube orientation is horizontal (the tube`s inlet and outlet connection points on the tubesheet are at the same elevation). Previous RELAP5 input decks for horizontal steam generators have been either very simplistic (Loviisa PWR) or used a vertical tube orientation (N-Reactor). This paper will present the development and testing of a RELAP5 horizontal steam generator model, complete with a simple secondary water level control system, that accounts for the dynamic flow conditions which exist inside horizontal steam generators.

  14. Performance of weather research and forecasting model with variable horizontal resolution

    NASA Astrophysics Data System (ADS)

    Kumar, Prashant; Ojha, Satya P.; Singh, Randhir; Kishtawal, C. M.; Pal, P. K.

    2015-08-01

    In this paper, Weather Research and Forecasting (WRF) model is employed with three different horizontal grid spacings (45, 15 and 5 km) to assess the impact of horizontal resolution on short-range weather forecast. Simulations are carried out daily at 0000 UTC over the Indian region during the entire month of July 2011. A rigorous validation is performed against surface observations, radiosonde measurements and Tropical Rainfall Measuring Mission (TRMM) 3B42 merged rainfall product. Results show that horizontal resolution has a substantial impact on the WRF model forecast, particularly on the near surface temperature, moisture, winds and rainfall forecasts. Relative to 45-km horizontal grid spacing, 24-h forecasts of near surface temperature, moisture and winds are improved by ˜15, 9 and 4 %, respectively, when horizontal grid spacing is reduced to 5 km. Noteworthy improvement is also seen in the 24-h rainfall forecasts of the WRF model as the horizontal grid spacing decreased from 45 to 5 km. Larger improvements are observed over the Western Ghats and northeastern part of India compared to central India, which demonstrate the importance of finer resolution over the mountainous terrain compared to plains.

  15. Comparison of condylar displacement between three biotypological facial groups by using mounted models and a mandibular position indicator

    PubMed Central

    Tavares, José Pedro; Lopes, Jorge Dias; Ferreira, Afonso Pinhão

    2014-01-01

    Objective Facial-type-associated variations in diagnostic features have several implications in orthodontics. For example, in hyperdivergent craniofacial types, growth imbalances are compensated by displacement of the condyle. When diagnosis and treatment planning involves centric relation (CR), detailed knowledge of the condylar position is desirable. The present study aimed to measure condylar displacement (CD) between CR and maximum intercuspation in three facial types of an asymptomatic orthodontic population. Methods The study was conducted in 108 patients classified into three groups of 36 individuals each (27 women and 9 men; mean age, 20.5 years), based on the following facial patterns: hyperdivergent, hypodivergent, and intermediate. To quantify CD along the horizontal and vertical axes, the condylar position was analyzed using mounted casts on a semi-adjustable articulator and a mandibular position indicator. The Student t-test was used to compare CD between the groups. Results Vertical displacement was found to be significantly different between the hyperdivergent and hypodivergent groups (p < 0.0002) and between the hyperdivergent and intermediate groups (p < 0.0006). The differences in horizontal displacement were not significant between the groups. In each group, vertical CD was more evident than horizontal displacement was. Conclusions All facial types, especially the hyperdivergent type, carried a significantly high risk of CD. Therefore, the possibility of CD should be carefully evaluated and considered in the assessment of all orthodontic cases in order to accurately assess jaw relationships and avoid possible misdiagnosis. PMID:25473647

  16. Validation of high displacement piezoelectric actuator finite element models

    NASA Astrophysics Data System (ADS)

    Taleghani, Barmac K.

    2000-08-01

    The paper presents the results obtained by using NASTRAN and ANSYS finite element codes to predict doming of the THUNDER piezoelectric actuators during the manufacturing process and subsequent straining due to an applied input voltage. To effectively use such devices in engineering applications, modeling and characterization are essential. Length, width, dome height, and thickness and important parameters for users of such devices. Therefore, finite element models were used to assess the effects of these parameters. NASTRAN and ANSYS used different methods for modeling piezoelectric effects. In NASTRAN, a thermal analogy was used to represent voltage at nodes as equivalent temperatures, while ANSYS processed the voltage directly using piezoelectric finite elements. The results of finite element models were validated by using the experimental results.

  17. Validation of High Displacement Piezoelectric Actuator Finite Element Models

    NASA Technical Reports Server (NTRS)

    Taleghani, B. K.

    2000-01-01

    The paper presents the results obtained by using NASTRAN(Registered Trademark) and ANSYS(Regitered Trademark) finite element codes to predict doming of the THUNDER piezoelectric actuators during the manufacturing process and subsequent straining due to an applied input voltage. To effectively use such devices in engineering applications, modeling and characterization are essential. Length, width, dome height, and thickness are important parameters for users of such devices. Therefore, finite element models were used to assess the effects of these parameters. NASTRAN(Registered Trademark) and ANSYS(Registered Trademark) used different methods for modeling piezoelectric effects. In NASTRAN(Registered Trademark), a thermal analogy was used to represent voltage at nodes as equivalent temperatures, while ANSYS(Registered Trademark) processed the voltage directly using piezoelectric finite elements. The results of finite element models were validated by using the experimental results.

  18. The introduction of horizontal inhomogeneity of meteorological conditions in the EOSTAR propagation model

    NASA Astrophysics Data System (ADS)

    van Eijk, A. M. J.; Kunz, G. J.

    2006-08-01

    The effective field-of-view of an electro-optical sensor in a given meteorological scenario can be evaluated using a ray-tracer. The resulting ray trace diagram also provides information pertinent to the quality (distortion, mirages) of the image being viewed by the sensor. The EOSTAR (Electro Optical Signal Transmission And Ranging) model suite contains a ray tracer that has been upgraded to take into account horizontal inhomogeneities in the atmosphere, such as temperature gradients as observed in coastal areas where (e.g.) cold air flows out over warm waters. Initial results for horizontally inhomogeneous atmospheres are presented and compared to calculations for horizontally homogeneous atmospheres. It is shown that the horizontal inhomogeneity of temperature should be taken into account when assessing sensor performance.

  19. A model for diffuse and global irradiation on horizontal surfaces

    SciTech Connect

    Jain, P.C. )

    1990-01-01

    The intensity of the direct radiation and the diffuse radiation at any time on a horizontal surface are each expressed as fractions of the intensity of the extraterrestrial radiation. Using these and assuming a random distribution of the bright sunshine hours and not too wide variations in the values of the transmission coefficients, a number of relations for estimating the global and the diffuse irradiation are derived. Two of the relations derived, including the Angstroem correlation for estimating the global irradiation, are already known empirically while several new correlations have been derived. The relations derived in this paper are: (i) H{sub d}/H{sub o} = a{sub 1} + b{sub 1} (S/S{sub o}); (ii) H/H{sub o} = A{sub 2} + b{sub 2} (S/S{sub o}); (iii) H{sub D}/H{sub o} = a{sub 3} + b{sub 3} (H/H{sub o}); (iv) H{sub D}/H = a{sub 4} + b{sub 4} (h{sub o}/) (v) H/(H{minus}H{sub D}) = a{sub 5} + b{sub 5} (S{sub o}/S); (vi) H{sub D}/(H{minus}H{sub D}) = A{sub 6} + b{sub 6} (S{sub o}/S); (vii) H/H{sub D} = a{sub 7} + b{sub 7} (S/S{sub o}); (viii) H/H{sub D} = A{sub 1} + A{sub 2} (S/S{sub o}) + A{sub 3} (S/S{sub o}){sup 2}. The study identifies three independent basic parameters and the constants appearing in the various equations as simple functions of these three basic parameters. This provides unification and inter-relationships between the various constants. Experimental data for the diffuse irradiation, the global irradiation and the bright sunshine duration for Macerata (Italy), Salisbury and Bulawayo (Zimbabwe) is found to show good correlation for the linear eqns (i) to (vii), and the nature and the interrelationships of the constants is found to be as predicted by theory.

  20. Modeling and parameterization of horizontally inhomogeneous cloud radiative properties

    NASA Technical Reports Server (NTRS)

    Welch, R. M.

    1995-01-01

    One of the fundamental difficulties in modeling cloud fields is the large variability of cloud optical properties (liquid water content, reflectance, emissivity). The stratocumulus and cirrus clouds, under special consideration for FIRE, exhibit spatial variability on scales of 1 km or less. While it is impractical to model individual cloud elements, the research direction is to model a statistical ensembles of cloud elements with mean-cloud properties specified. The major areas of this investigation are: (1) analysis of cloud field properties; (2) intercomparison of cloud radiative model results with satellite observations; (3) radiative parameterization of cloud fields; and (4) development of improved cloud classification algorithms.

  1. Study of Surface Displacements on Tunnelling under Buildings Using 3DEC Numerical Modelling

    PubMed Central

    Rebello, Nalini; Sastry, V. R.

    2014-01-01

    Underground structures at shallow depths are often constructed for metro lines, either in loose or dense layered soils. Tunnelling in urban areas is predominantly under surface structures and on tunnelling, innumerable changes in the form of distortion take place in strata surrounding the tunnel. Extent of displacement/damage to buildings or the tunnel-soil structure interaction depends on the type of building and nature of strata. Effect on displacements has been less studied in granular soils compared to other types of soils like clays. In this paper, parametric studies are conducted to find the displacements at surface, in granular soil conditions, due to varying building storeys and building eccentricities from the tunnel centre line. Effect of presence of geosynthetic layer under footings is further studied. Prior to the parametric studies, validity of the model used is checked with field data available for a stretch of tunnel in South India. Results of simulation studies reveal that inclusion of building reduces displacements at the surface in the dense strata. In very dense strata, the displacements increase as compared to the case without a building. As the centre of the building moves away from the tunnel centre line, settlement above the tunnel matches displacements in the case without building. Applicability of 3DEC software is checked with respect to the present study.

  2. Model for vacancy-loop nucleation in displacement cascades

    NASA Astrophysics Data System (ADS)

    Kapinos, V. G.; Bacon, D. J.

    1995-08-01

    A model is proposed for the nucleation of collapsed vacancy clusters in irradiated metals, based on the principle that a vacancy loop may be nucleated in a cascade which has melted and recrystallized. The equation of thermal conduction is solved using the discretization method and initial temperature and vacancy distributions given by the marlowe code. The model simulates the processes of heat propagation, local melting, absorption and release of latent heat, and the redistribution of the density within the melt. Under the influence of the temperature gradient, the concentration of vacancies in the depleted zone increases. Simulation of hundreds of cascades gives the distribution of zones as a function of vacancy concentration and number of vacancies in them, and it is assumed that critical values Ccr and Ncrv have to be achieved to produce a visible vacancy loop. However, if the concentration exceeds a value Camv under sufficiently fast cooling, for example under strong electron-phonon coupling (EPC), the melted zone cannot crystallize completely and solidifies instead to a semiamorphous core. This prevents collapse to a vacancy loop. The model has been used to calculate the yield and mean size of vacancy loops in ion-irradiated Cu, Ni, and Cu-Ge and Cu-Ni alloys. Physically reasonable values of Ccr, Ncr, and Camv have been obtained to give good agreement with experimental values of yield and size. Furthermore, the trends with alloy content can be explained, and it is found that EPC can have a strong influence on loop yield.

  3. Surface Hydrological Load Displacements from the National Land Data Assimilation System (NLDAS) model

    NASA Astrophysics Data System (ADS)

    Puskas, C. M.; Meertens, C. M.; Phillips, D. A.

    2015-12-01

    UNAVCO is currently developing forward displacement models from surface water stored in soil moisture, snowpack, and vegetation based on the National Land Data Assimilation System (NLDAS). UNAVCO already produces hydrological models from the Global Land Data Assimilation System (GLDAS), estimating the elastic loading from surface water at GPS coordinates for stations and processed by the GAGE Analysis Center. GLDAS incorporates satellite and ground observations into forcing parameters to be used for climate and weather models. The GLDAS forcing parameters include temperature, humidity, precipitation, radiation, wind, and pressure data at global 1º grid squares, excluding the oceanic surface. NLDAS uses the same set of forcing parameters but in an area restricted to the continental United States plus parts of Canada and Mexico and with a 0.125º grid. Research groups contribute Land Surface Models (LSMs) based on NLDAS or GLDAS to produce time series of modeled environmental parameters. Individual LSMs differ based on model equations and soil and vegetation properties. In this study we extract the parameters from the NLDAS LSMs to produce hydrologic displacement models at GPS station coordinates within the conterminous US. We check whether NLDAS displacement models can resolve regional variations due to topography that are smoothed in the GLDAS models. We compare the soil moisture, snowpack, and vegetation mass per area directly between the GLDAS and NLDAS LSMs, to see whether the mass variations between GLDAS and NLDAS are large enough to cause significant deformation changes. By comparing the hydrologic displacement models with GPS time series, we estimate how well the surface water loading predicts observed seasonal and secular GPS signals as opposed to tectonic signals. These comparisons will help us evaluate the NLDAS-derived displacement models as part of the process of developing a new model product for use in time series analysis, tectonic or hydrologic

  4. Empirical correction of a hydraulic model of mutual displacement of solutions in a porous bed

    SciTech Connect

    Kuznetskii, R.S.

    1986-09-10

    This paper seeks to experimentally verify and correct a hydraulic model for the forced displacement of a homogeneous solution in a porous or granular bed or in a pipe by calibrating the model against empirical data for the hydraulic behavior of sulfonated coal, an ion exchange resin, calcium carbonate, and diatomite.

  5. Newmark displacement model for landslides induced by the 2013 Ms 7.0 Lushan earthquake, China

    NASA Astrophysics Data System (ADS)

    Yuan, Renmao; Deng, Qinghai; Cunningham, Dickson; Han, Zhujun; Zhang, Dongli; Zhang, Bingliang

    2016-01-01

    Predicting approximate earthquake-induced landslide displacements is helpful for assessing earthquake hazards and designing slopes to withstand future earthquake shaking. In this work, the basic methodology outlined by Jibson (1993) is applied to derive the Newmark displacement of landslides based on strong ground-motion recordings during the 2013 Lushan Ms 7.0 earthquake. By analyzing the relationships between Arias intensity, Newmark displacement, and critical acceleration of the Lushan earthquake, formulas of the Jibson93 and its modified models are shown to be applicable to the Lushan earthquake dataset. Different empirical equations with new fitting coefficients for estimating Newmark displacement are then developed for comparative analysis. The results indicate that a modified model has a better goodness of fit and a smaller estimation error for the Jibson93 formula. It indicates that the modified model may be more reasonable for the dataset of the Lushan earthquake. The analysis of results also suggests that a global equation is not ideally suited to directly estimate the Newmark displacements of landslides induced by one specific earthquake. Rather it is empirically better to perform a new multivariate regression analysis to derive new coefficients for the global equation using the dataset of the specific earthquake. The results presented in this paper can be applied to a future co-seismic landslide hazard assessment to inform reconstruction efforts in the area affected by the 2013 Lushan Ms 7.0 earthquake, and for future disaster prevention and mitigation.

  6. Shell Tectonics: A Mechanical Model for Strike-slip Displacement on Europa

    NASA Technical Reports Server (NTRS)

    Rhoden, Alyssa Rose; Wurman, Gilead; Huff, Eric M.; Manga, Michael; Hurford, Terry A.

    2012-01-01

    We introduce a new mechanical model for producing tidally-driven strike-slip displacement along preexisting faults on Europa, which we call shell tectonics. This model differs from previous models of strike-slip on icy satellites by incorporating a Coulomb failure criterion, approximating a viscoelastic rheology, determining the slip direction based on the gradient of the tidal shear stress rather than its sign, and quantitatively determining the net offset over many orbits. This model allows us to predict the direction of net displacement along faults and determine relative accumulation rate of displacement. To test the shell tectonics model, we generate global predictions of slip direction and compare them with the observed global pattern of strike-slip displacement on Europa in which left-lateral faults dominate far north of the equator, right-lateral faults dominate in the far south, and near-equatorial regions display a mixture of both types of faults. The shell tectonics model reproduces this global pattern. Incorporating a small obliquity into calculations of tidal stresses, which are used as inputs to the shell tectonics model, can also explain regional differences in strike-slip fault populations. We also discuss implications for fault azimuths, fault depth, and Europa's tectonic history.

  7. Hurricanes in an Aquaplanet World: Implications of the Impacts of External Forcing and Model Horizontal Resolution

    SciTech Connect

    Li, Fuyu; Collins, William D.; Wehner, Michael F.; Leung, Lai-Yung R.

    2013-06-02

    High-resolution climate models have been shown to improve the statistics of tropical storms and hurricanes compared to low-resolution models. The impact of increasing horizontal resolution in the tropical storm simulation is investigated exclusively using a series of Atmospheric Global Climate Model (AGCM) runs with idealized aquaplanet steady-state boundary conditions and a fixed operational storm-tracking algorithm. The results show that increasing horizontal resolution helps to detect more hurricanes, simulate stronger extreme rainfall, and emulate better storm structures in the models. However, increasing model resolution does not necessarily produce stronger hurricanes in terms of maximum wind speed, minimum sea level pressure, and mean precipitation, as the increased number of storms simulated by high-resolution models is mainly associated with weaker storms. The spatial scale at which the analyses are conducted appears to have more important control on these meteorological statistics compared to horizontal resolution of the model grid. When the simulations are analyzed on common low-resolution grids, the statistics of the hurricanes, particularly the hurricane counts, show reduced sensitivity to the horizontal grid resolution and signs of scale invariant.

  8. Dual permeability flow behavior for modeling horizontal well production in fractured-vuggy carbonate reservoirs

    NASA Astrophysics Data System (ADS)

    Guo, Jian-Chun; Nie, Ren-Shi; Jia, Yong-Lu

    2012-09-01

    SummaryFractured-vuggy carbonate reservoirs are composed of by matrix, fracture, and vug systems. This paper is the first investigation into the dual permeability flow issue for horizontal well production in a fractured-vuggy carbonate reservoir. Considering dispersed vugs in carbonate reservoirs and treating media directly connected with horizontal wellbore as the matrix and fracture systems, a test analysis model of a horizontal well was created, and triple porosity and dual permeability flow behavior were modeled. Standard log-log type curves were drawn up by numerical simulation and flow behavior characteristics were thoroughly analyzed. Numerical simulations showed that type curves are dominated by external boundary conditions as well as the permeability ratio of the fracture system to the sum of fracture and matrix systems. The parameter κ is only relevant to the dual permeability model, and if κ is one, then the dual permeability model is equivalent to the single permeability model. There are seven main flow regimes with constant rate of horizontal well production and five flow regimes with constant wellbore pressure of horizontal well production; different flow regimes have different flow behavior characteristics. Early radial flow and linear flow regimes are typical characteristics of horizontal well production; duration of early radial flow regime is usually short because formation thickness is generally less than 100 m. Derivative curves are W-shaped, which is a reflection of inter-porosity flows between matrix, fracture, and vug systems. A distorted W-shape, which could be produced in certain situations, such as one involving an erroneously low time of inter-porosity flows, would handicap the recognition of a linear flow regime. A real case application was successfully implemented, and some useful reservoir parameters (e.g., permeability and inter-porosity flow factor) were obtained from well testing interpretation.

  9. Framework for non-coherent interface models at finite displacement jumps and finite strains

    NASA Astrophysics Data System (ADS)

    Ottosen, Niels Saabye; Ristinmaa, Matti; Mosler, Jörn

    2016-05-01

    This paper deals with a novel constitutive framework suitable for non-coherent interfaces, such as cracks, undergoing large deformations in a geometrically exact setting. For this type of interface, the displacement field shows a jump across the interface. Within the engineering community, so-called cohesive zone models are frequently applied in order to describe non-coherent interfaces. However, for existing models to comply with the restrictions imposed by (a) thermodynamical consistency (e.g., the second law of thermodynamics), (b) balance equations (in particular, balance of angular momentum) and (c) material frame indifference, these models are essentially fiber models, i.e. models where the traction vector is collinear with the displacement jump. This constraints the ability to model shear and, in addition, anisotropic effects are excluded. A novel, extended constitutive framework which is consistent with the above mentioned fundamental physical principles is elaborated in this paper. In addition to the classical tractions associated with a cohesive zone model, the main idea is to consider additional tractions related to membrane-like forces and out-of-plane shear forces acting within the interface. For zero displacement jump, i.e. coherent interfaces, this framework degenerates to existing formulations presented in the literature. For hyperelasticity, the Helmholtz energy of the proposed novel framework depends on the displacement jump as well as on the tangent vectors of the interface with respect to the current configuration - or equivalently - the Helmholtz energy depends on the displacement jump and the surface deformation gradient. It turns out that by defining the Helmholtz energy in terms of the invariants of these variables, all above-mentioned fundamental physical principles are automatically fulfilled. Extensions of the novel framework necessary for material degradation (damage) and plasticity are also covered.

  10. Neoliberalism in Historical Light: How Business Models Displaced Science Education Goals in Two Eras

    ERIC Educational Resources Information Center

    Hayes, Kathryn N.

    2016-01-01

    Although a growing body of work addresses the current role of neoliberalism in displacing democratic equality as a goal of public education, attempts to parse such impacts rarely draw from historical accounts. At least one tenet of neoliberalism--the application of business models to public institutions--was also pervasive at the turn of the 20th…

  11. Displacements Of Brownian Particles In Terms Of Marian Von Smoluchowski's Heuristic Model

    ERIC Educational Resources Information Center

    Klein, Hermann; Woermann, Dietrich

    2005-01-01

    Albert Einstein's theory of the Brownian motion, Marian von Smoluchowski's heuristic model, and Perrin's experimental results helped to bring the concept of molecules from a state of being a useful hypothesis in chemistry to objects existing in reality. Central to the theory of Brownian motion is the relation between mean particle displacement and…

  12. Upward and inward displacements of the acetabular component increase stress on femoral head in single endoprothesis models

    PubMed Central

    Zhang, Zhiqi; Kang, Yan; Chen, Yi; Liao, Weiming

    2009-01-01

    The centre of rotation of the hip can be displaced in hip dysplasia and revision arthroplasty. This study examined the effect of artificial femoral head load after acetabular component displacement in total hip arthroplasty. Sixteen total hip arthroplasty models of human cadaver specimens were reconstructed, and under different acetabular component position, the load around the femoral head was evaluated by strain gages. The results showed that the load was higher in the same specimens when the cup was moved 2 mm inward or upward, especially after the cup was moved more than 6 mm, and the load had an increasing effect in the inward group. In the upward group, an increasing effect happened at 8 mm upward displacement, but the stress value decreased from 4 mm to 6 mm upward displacement. In the same moving distance, the stress of inward displacement is obviously higher than upward displacement. Altogether, the results suggested that for both inward displacement and upward displacement of the acetabular cup, the load around the femoral head increased gradually, while the distance of the inward displacement and the superior displacement was increased. The greater the displacement, the bigger the loading contact stress. The upward displacement caused less stress change on the femoral head. The stress of the 6 mm upward position was lower than nearby positions; perhaps this site represented a stress buffering zone. PMID:19424694

  13. Axisymmetric model of drop spreading on a horizontal surface

    NASA Astrophysics Data System (ADS)

    Mistry, Aashutosh; Muralidhar, K.

    2015-09-01

    Spreading of an initially spherical liquid drop over a textured surface is analyzed by solving an integral form of the governing equations. The mathematical model extends Navier-Stokes equations by including surface tension at the gas-liquid boundary and a force distribution at the three phase contact line. While interfacial tension scales with drop curvature, the motion of the contact line depends on the departure of instantaneous contact angle from its equilibrium value. The numerical solution is obtained by discretizing the spreading drop into disk elements. The Bond number range considered is 0.01-1. Results obtained for sessile drops are in conformity with limiting cases reported in the literature [J. C. Bird et al., "Short-time dynamics of partial wetting," Phys. Rev. Lett. 100, 234501 (2008)]. They further reveal multiple time scales that are reported in experiments [K. G. Winkels et al., "Initial spreading of low-viscosity drops on partially wetting surfaces," Phys. Rev. E 85, 055301 (2012) and A. Eddi et al., "Short time dynamics of viscous drop spreading," Phys. Fluids 25, 013102 (2013)]. Spreading of water and glycerin drops over fully and partially wetting surfaces is studied in terms of excess pressure, wall shear stress, and the dimensions of the footprint. Contact line motion is seen to be correctly captured in the simulations. Water drops show oscillations during spreading while glycerin spreads uniformly over the surface.

  14. Horizontal dispersion in shelf seas: High resolution modelling as an aid to sparse sampling

    NASA Astrophysics Data System (ADS)

    Stashchuk, Nataliya; Vlasenko, Vasiliy; Inall, Mark E.; Aleynik, Dmitry

    2014-11-01

    The ability of a hydrodynamic model to reproduce the results of a dye release experiment conducted in a wide shelf sea environment was investigated with the help of the Massachusetts Institute of Technology general circulation model (MITgcm). In the field experiment a fluorescent tracer, Rhodamine WT, was injected into the seasonal pycnocline, and its evolution was tracked for two days using a towed undulating vehicle equipped with a fluorometer and a CTD. With a 50 m horizontal resolution grid, and with three different forcings initialized in the model (viz: tides, stationary current, and wind stress on the free surface), it was possible to replicate the dye patch evolution quite accurately. The mechanisms responsible for the enhancement of horizontal dispersion were investigated on the basis of the model results. It was found that enhancement of the dye dispersion was controlled by vertically sheared currents that, in combination with vertical diapycnal mixing, led to a substantial increase in the “effective” horizontal mixing. The values of “effective” horizontal mixing found from the model runs were in good agreement with those obtained from in-situ data, and the probable degree to which the observational techniques undersampled the dye patch was revealed.

  15. Displacement Models for THUNDER Actuators having General Loads and Boundary Conditions

    NASA Technical Reports Server (NTRS)

    Wieman, Robert; Smith, Ralph C.; Kackley, Tyson; Ounaies, Zoubeida; Bernd, Jeff; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    This paper summarizes techniques for quantifying the displacements generated in THUNDER actuators in response to applied voltages for a variety of boundary conditions and exogenous loads. The PDE (partial differential equations) models for the actuators are constructed in two steps. In the first, previously developed theory quantifying thermal and electrostatic strains is employed to model the actuator shapes which result from the manufacturing process and subsequent repoling. Newtonian principles are then employed to develop PDE models which quantify displacements in the actuator due to voltage inputs to the piezoceramic patch. For this analysis, drive levels are assumed to be moderate so that linear piezoelectric relations can be employed. Finite element methods for discretizing the models are developed and the performance of the discretized models are illustrated through comparison with experimental data.

  16. Application of a characteristic periods-based (CPB) approach to estimate earthquake-induced displacements of landslides through dynamic numerical modelling

    NASA Astrophysics Data System (ADS)

    Martino, S.; Lenti, L.; Delgado, J.; Garrido, J.; Lopez-Casado, C.

    2016-07-01

    The interaction between seismic waves and slopes is an important topic to provide reliable scenarios for earthquake-(re)triggered landslides. The physical properties of seismic waves as well as slope topography and geology can significantly modify the local seismic response, influencing landslide triggering. A novel approach is here applied to two case studies in Andalusia (southern Spain) for computing the expected earthquake-induced displacements of existing landslide masses. Towards this aim, dynamic stress-strain numerical modelling was carried out using a selection of seismic signals characterized by different spectral content and energy. In situ geophysical measurements, consisting of noise records and temporary seismometric arrays, were carried out to control the numerical outputs in terms of local seismic response. The results consist of relationships between the characteristic period, Tm, of the seismic signals and the characteristic periods of the landslide masses, related to the thickness (Ts) and length (Tl), respectively. These relationships show that the larger the horizontal dimension (i.e. length of landslide) of a landslide is, the more effective the contribution (to the resulting coseismic displacement) of the long-period seismic waves is, as the maximum displacements are expected for a low Tm at each energy level of the input. On the other hand, when the local seismic response mainly depends on stratigraphy (i.e. landslide thickness), the maximum expected displacements occur close to the resonance period of the landslide, except for high-energy seismic inputs.

  17. Application of a Characteristic Periods-Based (CPB) approach to estimate earthquake-induced displacements of landslides through dynamic numerical modelling

    NASA Astrophysics Data System (ADS)

    Martino, S.; Lenti, L.; Delgado, J.; Garrido, J.; Casado, C. Lopez

    2016-04-01

    The interaction between seismic waves and slope is an important topic to provide reliable scenarios for earthquake-(re)triggered landslides. The physical properties of seismic waves as well as slope topography and geology can significantly modify the local seismic response, influencing landslide triggering. A novel approach is here applied to two case studies in Andalusia (southern Spain) for computing the expected earthquake-induced displacements of existing landslide masses. Towards this aim, dynamic stress-strain numerical modelling was carried out using a selection of seismic signals characterized by different spectral content and energy. In situ geophysical measurements, consisting of noise records and temporary seismometric arrays, were carried out to control the numerical outputs in terms of the local seismic response. The results consist of relationships between the characteristic period, Tm, of the seismic signals and the characteristic periods of the landslide masses, related to the thickness (Ts) and length (Tl), respectively. These relationships show that the larger the horizontal dimension (i.e., length of landslide) of a landslide is, the more effective the contribution (to the resulting co-seismic displacement) of the long-period seismic waves is, as the maximum displacements are expected for a low Tm at each energy level of the input. On the other hand, when the local seismic response mainly depends on stratigraphy (i.e., landslide thickness), the maximum expected displacements occur close to the resonance period of the landslide, except for high-energy seismic inputs.

  18. Impact of Horizontal Resolution on the Simulation of Tropical Storms in an Idealized Climate Model

    NASA Astrophysics Data System (ADS)

    Li, F.; Collins, W.; Wehner, M. F.; Williamson, D.; Olson, J. G.

    2011-12-01

    High-resolution climate models have been shown to improve the statistics of tropical storms. The impact of increasing horizontal resolution in the tropical storm simulation is investigated exclusively using a series of AGCM runs with idealized "aquaplanet-steady-state" boundary conditions and a fixed storm tracking algorithm. The results show that increasing horizontal resolution helps to detect more tropical storms, primarily due to the simulated higher vorticity. High resolution simulations produce storms with lower depressions, stronger precipitation intensities, and more detailed storm structures. They also produce more storm systems at the lower latitudes, with the quite localized storm trajectories.

  19. Diagnostic Evaluation of Ozone Production and Horizontal Transport in a Regional Photochemical Air Quality Modeling System

    EPA Science Inventory

    A diagnostic model evaluation effort has been performed to focus on photochemical ozone formation and the horizontal transport process since they strongly impact the temporal evolution and spatial distribution of ozone (O3) within the lower troposphere. Results from th...

  20. Enhanced mathematical modeling of the displacement amplification ratio for piezoelectric compliant mechanisms

    NASA Astrophysics Data System (ADS)

    Ling, Mingxiang; Cao, Junyi; Zeng, Minghua; Lin, Jing; Inman, Daniel J.

    2016-07-01

    Piezo-actuated, flexure hinge-based compliant mechanisms have been frequently used in precision engineering in the last few decades. There have been a considerable number of publications on modeling the displacement amplification behavior of rhombus-type and bridge-type compliant mechanisms. However, due to an unclear geometric approximation and mechanical assumption between these two flexures, it is very difficult to obtain an exact description of the kinematic performance using previous analytical models, especially when the designed angle of the compliant mechanisms is small. Therefore, enhanced theoretical models of the displacement amplification ratio for rhombus-type and bridge-type compliant mechanisms are proposed to improve the prediction accuracy based on the distinct force analysis between these two flexures. The energy conservation law and the elastic beam theory are employed for modeling with consideration of the translational and rotational stiffness. Theoretical and finite elemental results show that the prediction errors of the displacement amplification ratio will be enlarged if the bridge-type flexure is simplified as a rhombic structure to perform mechanical modeling. More importantly, the proposed models exhibit better performance than the previous models, which is further verified by experiments.

  1. The effects of three-dimensional heterogeneous Earth model of coseismic displacement changes of the Sumatra earthquake of 26 December 2004

    NASA Astrophysics Data System (ADS)

    Qu, Wulin; Zhang, Bei; Huang, Luyuan; Cheng, Huihong; Shi, Yaolin

    2016-04-01

    The 26 December 2004 Sumatra-Andaman earthquake with moment magnitude (Mw) of 9.1 to 9.3 is the first great earthquake recorded by digital broadband, high-dynamic-range seismometers and global positioning system (GPS) equipment, which recorded many high-quality geophysical data sets. The spherical curvature is not negligible in far field especially for large event and the real Earth is laterally inhomogeneity and the analytical results still are difficult to explain the geodetic measurements. We use equivalent body force finite elements method Zhang et al. (2015) and mesh the whole earth, to compute global co-seismic displacements using four fault slip models of the 2004 Sumatra earthquake provided by different authors. Comparisons of calculated co-seismic displacements and GPS show that the confidences are well in near field for four models, and the confidences are according to different models. In the whole four models, the Chlieh model (Chlieh et al., 2007) is the best as this slip model not only accord well with near field data but also far field data. And then we use the best slip model, Chlieh model to explore influence of three dimensional lateral earth structure on both layered spherically symmetric (PREM) and real 3-D heterogeneous earth model (Crust 1.0 model and GyPSuM). Results show that the effects of 3-D heterogeneous earth model are not negligible and decrease concomitantly with increasing distance from the epicenter. The relative effects of 3-D crust model are 23% and 40% for horizontal and vertical displacements, respectively. The effects of the 3-D mantle model are much smaller than that of 3-D crust model but with wider impacting area.

  2. Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

    SciTech Connect

    Wampler, William R. Myers, Samuel M.

    2015-01-28

    A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers, and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.

  3. Model for transport and reaction of defects and carriers within displacement cascades in gallium arsenide

    NASA Astrophysics Data System (ADS)

    Wampler, William R.; Myers, Samuel M.

    2015-01-01

    A model is presented for recombination of charge carriers at evolving displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with the details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers, and defects within a representative spherically symmetric cluster of defects. The initial radial defect profiles within the cluster were determined through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to displacement damage from energetic particle irradiation.

  4. Model for continuously scanning ultrasound vibrometer sensing displacements of randomly rough vibrating surfaces.

    PubMed

    Ratilal, Purnima; Andrews, Mark; Donabed, Ninos; Galinde, Ameya; Rappaport, Carey; Fenneman, Douglas

    2007-02-01

    An analytic model is developed for the time-dependent ultrasound field reflected off a randomly rough vibrating surface for a continuously scanning ultrasound vibrometer system in bistatic configuration. Kirchhoff's approximation to Green's theorem is applied to model the three-dimensional scattering interaction of the ultrasound wave field with the vibrating rough surface. The model incorporates the beam patterns of both the transmitting and receiving ultrasound transducers and the statistical properties of the rough surface. Two methods are applied to the ultrasound system for estimating displacement and velocity amplitudes of an oscillating surface: incoherent Doppler shift spectra and coherent interferometry. Motion of the vibrometer over the randomly rough surface leads to time-dependent scattering noise that causes a randomization of the received signal spectrum. Simulations with the model indicate that surface displacement and velocity estimation are highly dependent upon the scan velocity and projected wavelength of the ultrasound vibrometer relative to the roughness height standard deviation and correlation length scales of the rough surface. The model is applied to determine limiting scan speeds for ultrasound vibrometer measuring ground displacements arising from acoustic or seismic excitation to be used in acoustic landmine confirmation sensing. PMID:17348511

  5. Stress Analysis of Anterior-Disc-Displaced Temporomandibular Joint Using Individual Finite Element Model

    NASA Astrophysics Data System (ADS)

    Tanaka, Masao; Tanaka, Eiji; Todoh, Masahiro; Asai, Daisuke; Kuroda, Yukiko

    Temporomandibular joint (TMJ) disorder relates to the biomechanical irregularity of the structual joint components, and the behavior of soft tissue components is considered as a key to understand the biomechanical condition in the TMJ. The configuration of joint components, however, closely depends on individual patients. In this study, attention has been focused on the stress and displacement of irregular TMJs with anterior disc displacement. Using biplane magnetic resonance (MR) images, typical anterior-disc-displaced (ADD) TMJ of a patient with temporomandibular disorder has been modeled individually. The stress distribution in ADD TMJs has been compared with that in normal TMJs. Parameter studies with the elastic modulus have been carried out and it revealed that the stress distribution in the TMJ is highly dependent on the connective tissue modulus as well as disc modulus in the case of ADD TMJ, and that the disc displacement due to mouth opening movement depends on disc modulus in normal TMJ but depends on retrodiscal connective tissue in ADD TMJ.

  6. Cartilage changes link retrognathic mandibular growth to TMJ disc displacement in a rabbit model.

    PubMed

    Bryndahl, F; Warfvinge, G; Eriksson, L; Isberg, A

    2011-06-01

    Recent experimental research demonstrated that non-reducing temporomandibular joint (TMJ) disc displacement in growing rabbits impaired mandibular growth. TMJ disc displacement is also shown to induce histological changes of the condylar cartilage. The authors hypothesized that the severity of these changes would correlate to the magnitude of mandibular growth. Bilateral non-reducing TMJ disc displacement was surgically created in 10 growing New Zealand White rabbits. Ten additional rabbits constituted a sham operated control group. Aided by tantalum implants, growth was cephalometrically determined for each mandibular side during a period equivalent to childhood and adolescence in man. At the end of the growth period, histologically classified cartilage features were correlated with the assessed ipsilateral mandibular growth. Non-reducing displacement of the TMJ disc during the growth period induced histological reactions of the condylar cartilage in the rabbit model. The severity of cartilage changes was inversely correlated to the magnitude and the direction of mandibular growth, which resulted in a retrognathic growth pattern. PMID:21334177

  7. Lower Bound on the Mean Square Displacement of Particles in the Hard Disk Model

    NASA Astrophysics Data System (ADS)

    Richthammer, Thomas

    2016-08-01

    The hard disk model is a 2D Gibbsian process of particles interacting via pure hard core repulsion. At high particle density the model is believed to show orientational order, however, it is known not to exhibit positional order. Here we investigate to what extent particle positions may fluctuate. We consider a finite volume version of the model in a box of dimensions 2 n × 2 n with arbitrary boundary configuration, and we show that the mean square displacement of particles near the center of the box is bounded from below by c log n. The result generalizes to a large class of models with fairly arbitrary interaction.

  8. Measurement and modeling of solar irradiance components on horizontal and tilted planes

    SciTech Connect

    Padovan, Andrea; Col, Davide del

    2010-12-15

    In this work new measurements of global and diffuse solar irradiance on the horizontal plane and global irradiance on planes tilted at 20 and 30 oriented due South and at 45 and 65 oriented due East are used to discuss the modeling of solar radiation. Irradiance data are collected in Padova (45.4 N, 11.9 E, 12 m above sea level), Italy. Some diffuse fraction correlations have been selected to model the hourly diffuse radiation on the horizontal plane. The comparison with the present experimental data shows that their prediction accuracy strongly depends on the sky characteristics. The hourly irradiance measurements taken on the tilted planes are compared with the estimations given by one isotropic and three anisotropic transposition models. The use of an anisotropic model, based on a physical description of the diffuse radiation, provides a much better accuracy, especially when measurements of the diffuse irradiance on the horizontal plane are not available and thus transposition models have to be applied in combination with a diffuse fraction correlation. This is particularly significant for the planes oriented away from South. (author)

  9. Biomechanical model-based displacement estimation in micro-sensor motion capture

    NASA Astrophysics Data System (ADS)

    Meng, X. L.; Zhang, Z. Q.; Sun, S. Y.; Wu, J. K.; Wong, W. C.

    2012-05-01

    In micro-sensor motion capture systems, the estimation of the body displacement in the global coordinate system remains a challenge due to lack of external references. This paper proposes a self-contained displacement estimation method based on a human biomechanical model to track the position of walking subjects in the global coordinate system without any additional supporting infrastructures. The proposed approach makes use of the biomechanics of the lower body segments and the assumption that during walking there is always at least one foot in contact with the ground. The ground contact joint is detected based on walking gait characteristics and used as the external references of the human body. The relative positions of the other joints are obtained from hierarchical transformations based on the biomechanical model. Anatomical constraints are proposed to apply to some specific joints of the lower body to further improve the accuracy of the algorithm. Performance of the proposed algorithm is compared with an optical motion capture system. The method is also demonstrated in outdoor and indoor long distance walking scenarios. The experimental results demonstrate clearly that the biomechanical model improves the displacement accuracy within the proposed framework.

  10. Estimating the Frequency of Horizontal Gene Transfer Using Phylogenetic Models of Gene Gain and Loss.

    PubMed

    Zamani-Dahaj, Seyed Alireza; Okasha, Mohamed; Kosakowski, Jakub; Higgs, Paul G

    2016-07-01

    We analyze patterns of gene presence and absence in a maximum likelihood framework with rate parameters for gene gain and loss. Standard methods allow independent gains and losses in different parts of a tree. While losses of the same gene are likely to be frequent, multiple gains need to be considered carefully. A gene gain could occur by horizontal transfer or by origin of a gene within the lineage being studied. If a gene is gained more than once, then at least one of these gains must be a horizontal transfer. A key parameter is the ratio of gain to loss rates, a/v We consider the limiting case known as the infinitely many genes model, where a/v tends to zero and a gene cannot be gained more than once. The infinitely many genes model is used as a null model in comparison to models that allow multiple gains. Using genome data from cyanobacteria and archaea, it is found that the likelihood is significantly improved by allowing for multiple gains, but the average a/v is very small. The fraction of genes whose presence/absence pattern is best explained by multiple gains is only 15% in the cyanobacteria and 20% and 39% in two data sets of archaea. The distribution of rates of gene loss is very broad, which explains why many genes follow a treelike pattern of vertical inheritance, despite the presence of a significant minority of genes that undergo horizontal transfer. PMID:27189546

  11. The impact of horizontal model grid resolution on the boundary layer structure over an idealized valley

    NASA Astrophysics Data System (ADS)

    Wagner, Johannes; Gohm, Alexander; Rotach, Mathias; Leukauf, Daniel; Posch, Christian

    2014-05-01

    The role of horizontal model grid resolution on the development of the daytime boundary layer over mountainous terrain is studied. A simple idealized valley topography with a cross-valley width of 20~km, a valley depth of 1.5~km and a constant surface heat flux forcing is used to generate upslope flows in a warming valley boundary layer. The goal of this study is to investigate differences in the upslope flow and boundary layer structure of the valley when its topography is either fully resolved, smoothed or not resolved by the numerical model. This is done by performing both large-eddy (LES) and kilometer-scale simulations with mesh sizes of 50, 1000, 2000, 4000, 5000 and 10000~m. In LES mode a valley inversion layer develops, which separates two vertically stacked circulation cells in an upper and lower boundary layer. These structures weaken with decreasing horizontal model grid resolution and change to a convective boundary layer similar to the one over an elevated flat plain when the valley is no longer resolved. Mean profiles of the LES run, which are obtained by horizontal averaging over the valley show a three-layer thermal structure and a secondary heat flux maximum at ridge height. Strong smoothing of the valley topography prevents the development of a valley inversion layer with stacked circulation cells and leads to higher valley temperatures due to smaller valley volumes. This investigation shows that a parameterization is needed in coarse resolution models to capture exchange processes over mountainous terrain.

  12. Oxygen-enhanced models for globular cluster stars. III - Horizontal-branch sequences

    NASA Technical Reports Server (NTRS)

    Dorman, Ben

    1992-01-01

    A large grid of horizontal-branch (HB) evolutionary sequences which have been calculated with core expansion and semiconvection and with enhanced oxygen composition are presented and described. Tracks for 10 different metallicities are computed; they range from (Fe/H) = -0.47 to -2.26 and comprise a total of 115 sequences. The evolution is traced from the zero-age horizontal-branch (ZAHB) to the lower AGB at a point where log L/solar luminosity = 2.25. All of the sequences are illustrated on both the theoretical H-R diagram and on the B, V color-magnitude diagram. A complete set of tables for the ZAHB models and a representative sample of tabulations of the track parameters are provided. The phenomena which control HB evolution morphology, and existing certainties in theoretical HB models are discussed.

  13. Horizontal Position Optimal Solution Determination for the Satellite Laser Ranging Slope Model

    NASA Astrophysics Data System (ADS)

    Wang, Yu; Ai, Yu; Hu, Yu; Wang, RenLi

    2016-06-01

    According to the Gaussian-fit laser echo model and the terrain slope model, the regular mean value theorem and the asymptotic principle of the median point of the double integral mean value theorem are used to derive the optimal solution for the horizontal position of a single-mode laser echo. Through simulation experiments, the horizontal position results of the echo signal peak from various terrain slopes are analyzed. When ignoring the effect of the atmosphere and the surface roughness of the target, considering the geometric position of the Gaussian single-mode echo signal peak to be the center of the laser spot is highly accurate. However, as the accuracy significantly decreases when the slope is greater than 26°, making the range of the peak value of the single-mode echo data (for a slope of less than 26°) to be the range of the geometrical center of the laser spot can obtain a higher degree of accuracy.

  14. Horizontal soil water potential heterogeneity: simplifying approaches for crop water dynamics models

    NASA Astrophysics Data System (ADS)

    Couvreur, V.; Vanderborght, J.; Beff, L.; Javaux, M.

    2014-05-01

    Soil water potential (SWP) is known to affect plant water status, and even though observations demonstrate that SWP distribution around roots may limit plant water availability, its horizontal heterogeneity within the root zone is often neglected in hydrological models. As motive, using a horizontal discretisation significantly larger than one centimetre is often essential for computing time considerations, especially for large-scale hydrodynamics models. In this paper, we simulate soil and root system hydrodynamics at the centimetre scale and evaluate approaches to upscale variables and parameters related to root water uptake (RWU) for two crop systems: a densely seeded crop with an average uniform distribution of roots in the horizontal direction (winter wheat) and a wide-row crop with lateral variations in root density (maize). In a first approach, the upscaled water potential at soil-root interfaces was assumed to equal the bulk SWP of the upscaled soil element. Using this assumption, the 3-D high-resolution model could be accurately upscaled to a 2-D model for maize and a 1-D model for wheat. The accuracy of the upscaled models generally increased with soil hydraulic conductivity, lateral homogeneity of root distribution, and low transpiration rate. The link between horizontal upscaling and an implicit assumption on soil water redistribution was demonstrated in quantitative terms, and explained upscaling accuracy. In a second approach, the soil-root interface water potential was estimated by using a constant rate analytical solution of the axisymmetric soil water flow towards individual roots. In addition to the theoretical model properties, effective properties were tested in order to account for unfulfilled assumptions of the analytical solution: non-uniform lateral root distributions and transient RWU rates. Significant improvements were however only noticed for winter wheat, for which the first approach was already satisfying. This study confirms that the

  15. A 3D mathematical model for the horizontal anode baking furnace

    SciTech Connect

    Kocaefe, Y.S.; Dernedde, E.; Kocaefe, D.; Ouellet, R.; Jiao, Q.; Crowell, W.F.

    1996-10-01

    In the aluminum industry, carbon anodes are baked in large horizontal or vertical ring-type furnaces. The anode quality depends strongly on the baking conditions (heating rate, soaking time and final anode temperature). A three-dimensional mathematical model has been developed for a horizontal anode baking furnace to assess the effects of different parameters on the baking process and to improve the furnace operation and design at Noranda Aluminum Smelter in New Madrid, Missouri. The commercial CFD code CFDS-FLOW3D is used to solve the governing differential equations. The model gives the temperature, velocity and concentration distributions in the flue, and the variation of the temperature distribution with time in the pit. In this paper, a description of the 3D model for the horizontal anode baking furnace will be given. Some of the results from a case study will also be presented. The results show clearly the importance of flue geometry on the gas flow distribution in the flue and the heat transfer to the anodes.

  16. Numerical Modeling and Experimental Analysis of Scale Horizontal Axis Marine Hydrokinetic (MHK) Turbines

    NASA Astrophysics Data System (ADS)

    Javaherchi, Teymour; Stelzenmuller, Nick; Seydel, Joseph; Aliseda, Alberto

    2013-11-01

    We investigate, through a combination of scale model experiments and numerical simulations, the evolution of the flow field around the rotor and in the wake of Marine Hydrokinetic (MHK) turbines. Understanding the dynamics of this flow field is the key to optimizing the energy conversion of single devices and the arrangement of turbines in commercially viable arrays. This work presents a comparison between numerical and experimental results from two different case studies of scaled horizontal axis MHK turbines (45:1 scale). In the first case study, we investigate the effect of Reynolds number (Re = 40,000 to 100,000) and Tip Speed Ratio (TSR = 5 to 12) variation on the performance and wake structure of a single turbine. In the second case, we study the effect of the turbine downstream spacing (5d to 14d) on the performance and wake development in a coaxial configuration of two turbines. These results provide insights into the dynamics of Horizontal Axis Hydrokinetic Turbines, and by extension to Horizontal Axis Wind Turbines in close proximity to each other, and highlight the capabilities and limitations of the numerical models. Once validated at laboratory scale, the numerical model can be used to address other aspects of MHK turbines at full scale. Supported by DOE through the National Northwest Marine Renewable Energy Center.

  17. Mathematical models utilized in the retrieval of displacement information encoded in fringe patterns

    NASA Astrophysics Data System (ADS)

    Sciammarella, Cesar A.; Lamberti, Luciano

    2016-02-01

    All the techniques that measure displacements, whether in the range of visible optics or any other form of field methods, require the presence of a carrier signal. A carrier signal is a wave form modulated (modified) by an input, deformation of the medium. A carrier is tagged to the medium under analysis and deforms with the medium. The wave form must be known both in the unmodulated and the modulated conditions. There are two basic mathematical models that can be utilized to decode the information contained in the carrier, phase modulation or frequency modulation, both are closely connected. Basic problems connected to the detection and recovery of displacement information that are common to all optical techniques will be analyzed in this paper, focusing on the general theory common to all the methods independently of the type of signal utilized. The aspects discussed are those that have practical impact in the process of data gathering and data processing.

  18. A coronal magnetic field model with horizontal volume and sheet currents

    NASA Technical Reports Server (NTRS)

    Zhao, Xuepu; Hoeksema, J. Todd

    1994-01-01

    When globally mapping the observed photospheric magnetic field into the corona, the interaction of the solar wind and magnetic field has been treated either by imposing source surface boundary conditions that tacitly require volume currents outside the source surface or by limiting the interaction to thin current sheets between oppositely directed field regions. Yet observations and numerical Magnetohydrodynamic (MHD) calculations suggest the presence of non-force-free volume currents throughout the corona as well as thin current sheets in the neighborhoods of the interfaces between closed and open field lines or between oppositely directed open field lines surrounding coronal helmet-streamer structures. This work presents a model including both horizontal volume currents and streamer sheet currents. The present model builds on the magnetostatic equilibria developed by Bogdan and Low and the current-sheet modeling technique developed by Schatten. The calculation uses synoptic charts of the line-of-sight component of the photospheric magnetic field measured at the Wilcox Solar Observatory. Comparison of an MHD model with the calculated model results for the case of a dipole field and comparison of eclipse observations with calculations for CR 1647 (near solar minimum) show that this horizontal current-current-sheet model reproduces polar plumes and axes of corona streamers better than the source-surface model and reproduces polar plumes and axes of corona streamers better than the source-surface model and reproduces coro nal helmet structures better than the current-sheet model.

  19. Modelling the effects of horizontal and vertical shear in stratified turbulent flows

    NASA Astrophysics Data System (ADS)

    Umlauf, Lars

    2005-05-01

    Direct numerical simulations (DNS) and model results from a number of one-point turbulence models are compared for homogeneous, stably stratified flows. Because of their wide spread use in numerical ocean modelling, only explicit algebraic second-moment models are investigated. Considered are two types of shear flows with either purely vertical or purely horizontal shear. The dissipation rate is evaluated from the observation that the shear-number becomes independent of stratification for low to moderate Richardson numbers as soon as the flow approaches self-similarity. For the cases with vertical shear, it is found that all statistical models essentially reproduced the DNS results, though with different accuracy. In contrast, only the most recent model was able to predict the salient features of horizontally sheared flows, i.e. a steady-state Richardson number that is about an order of magnitude larger and a vertical mixing efficiency that is about twice as large compared to the case with vertical shear. This model also reproduced other key parameters like the turbulent Froude number and the turbulent Prandtl number with good accuracy, but it failed to predict quantitatively the reduction of the shear anisotropy with increasing stratification. For strong stratification, none of the models was able to describe the rapid decrease of the mixing efficiency associated with the collapse and fossilisation of turbulence.

  20. Validation of the Regional Climate Model ALARO with different dynamical downscaling approaches and different horizontal resolutions

    NASA Astrophysics Data System (ADS)

    Berckmans, Julie; Hamdi, Rafiq; De Troch, Rozemien; Giot, Olivier

    2015-04-01

    At the Royal Meteorological Institute of Belgium (RMI), climate simulations are performed with the regional climate model (RCM) ALARO, a version of the ALADIN model with improved physical parameterizations. In order to obtain high-resolution information of the regional climate, lateral bounary conditions (LBC) are prescribed from the global climate model (GCM) ARPEGE. Dynamical downscaling is commonly done in a continuous long-term simulation, with the initialisation of the model at the start and driven by the regularly updated LBCs of the GCM. Recently, more interest exists in the dynamical downscaling approach of frequent reinitializations of the climate simulations. For these experiments, the model is initialised daily and driven for 24 hours by the GCM. However, the surface is either initialised daily together with the atmosphere or free to evolve continuously. The surface scheme implemented in ALARO is SURFEX, which can be either run in coupled mode or in stand-alone mode. The regional climate is simulated on different domains, on a 20km horizontal resolution over Western-Europe and a 4km horizontal resolution over Belgium. Besides, SURFEX allows to perform a stand-alone or offline simulation on 1km horizontal resolution over Belgium. This research is in the framework of the project MASC: "Modelling and Assessing Surface Change Impacts on Belgian and Western European Climate", a 4-year project funded by the Belgian Federal Government. The overall aim of the project is to study the feedbacks between climate changes and land surface changes in order to improve regional climate model projections at the decennial scale over Belgium and Western Europe and thus to provide better climate projections and climate change evaluation tools to policy makers, stakeholders and the scientific community.

  1. Transport-reaction model for defect and carrier behavior within displacement cascades in gallium arsenide

    SciTech Connect

    Wampler, William R.; Myers, Samuel M.

    2014-02-01

    A model is presented for recombination of charge carriers at displacement damage in gallium arsenide, which includes clustering of the defects in atomic displacement cascades produced by neutron or ion irradiation. The carrier recombination model is based on an atomistic description of capture and emission of carriers by the defects with time evolution resulting from the migration and reaction of the defects. The physics and equations on which the model is based are presented, along with details of the numerical methods used for their solution. The model uses a continuum description of diffusion, field-drift and reaction of carriers and defects within a representative spherically symmetric cluster. The initial radial defect profiles within the cluster were chosen through pair-correlation-function analysis of the spatial distribution of defects obtained from the binary-collision code MARLOWE, using recoil energies for fission neutrons. Charging of the defects can produce high electric fields within the cluster which may influence transport and reaction of carriers and defects, and which may enhance carrier recombination through band-to-trap tunneling. Properties of the defects are discussed and values for their parameters are given, many of which were obtained from density functional theory. The model provides a basis for predicting the transient response of III-V heterojunction bipolar transistors to pulsed neutron irradiation.

  2. Performance of European chemistry transport models as function of horizontal resolution

    NASA Astrophysics Data System (ADS)

    Schaap, M.; Cuvelier, C.; Hendriks, C.; Bessagnet, B.; Baldasano, J. M.; Colette, A.; Thunis, P.; Karam, D.; Fagerli, H.; Graff, A.; Kranenburg, R.; Nyiri, A.; Pay, M. T.; Rouïl, L.; Schulz, M.; Simpson, D.; Stern, R.; Terrenoire, E.; Wind, P.

    2015-07-01

    Air pollution causes adverse effects on human health as well as ecosystems and crop yield and also has an impact on climate change trough short-lived climate forcers. To design mitigation strategies for air pollution, 3D Chemistry Transport Models (CTMs) have been developed to support the decision process. Increases in model resolution may provide more accurate and detailed information, but will cubically increase computational costs and pose additional challenges concerning high resolution input data. The motivation for the present study was therefore to explore the impact of using finer horizontal grid resolution for policy support applications of the European Monitoring and Evaluation Programme (EMEP) model within the Long Range Transboundary Air Pollution (LRTAP) convention. The goal was to determine the "optimum resolution" at which additional computational efforts do not provide increased model performance using presently available input data. Five regional CTMs performed four runs for 2009 over Europe at different horizontal resolutions. The models' responses to an increase in resolution are broadly consistent for all models. The largest response was found for NO2 followed by PM10 and O3. Model resolution does not impact model performance for rural background conditions. However, increasing model resolution improves the model performance at stations in and near large conglomerations. The statistical evaluation showed that the increased resolution better reproduces the spatial gradients in pollution regimes, but does not help to improve significantly the model performance for reproducing observed temporal variability. This study clearly shows that increasing model resolution is advantageous, and that leaving a resolution of 50 km in favour of a resolution between 10 and 20 km is practical and worthwhile. As about 70% of the model response to grid resolution is determined by the difference in the spatial emission distribution, improved emission allocation

  3. A model for fluid flow during saturated boiling on a horizontal cylinder

    NASA Technical Reports Server (NTRS)

    Kheyrandish, K.; Dalton, C.; Lienhard, J. H.

    1987-01-01

    A model has been developed to represent the vapor removal pattern in the vicinity of a cylinder during nucleate flow boiling across a horizontal cylinder. The model is based on a potential flow representation of the liquid and vapor regions and an estimate of the losses that should occur in the flow. Correlation of the losses shows a weak dependence on the Weber number and a slightly stronger dependence on the saturated liquid-to-vapor density ratio. The vapor jet thickness, which is crucial to the prediction of the burnout heat flux, and the shape of the vapor film are predicted. Both are verified by qualitative experimental observations.

  4. Optimized model of oriented-line-target detection using vertical and horizontal filters

    NASA Astrophysics Data System (ADS)

    Westland, Stephen; Foster, David H.

    1995-08-01

    A line-element target differing sufficiently in orientation from a background of line elements can be visually detected easily and quickly; orientation thresholds for such detection are lowest when the background elements are all vertical or all horizontal. A simple quantitative model of this performance was constructed from two classes of anisotropic filters, (2) nonlinear point transformation, and (3) estimation of a signal-to-noise ratio based on responses to images with and without a target. A Monte Carlo optimization procedure (simulated annealing) was used to determine the model parameter values required for providing an accurate description of psychophysical data on orientation increment thresholds.

  5. Rhombic micro-displacement amplifier for piezoelectric actuator and its linear and hybrid model

    NASA Astrophysics Data System (ADS)

    Chen, Jinglong; Zhang, Chunlin; Xu, Minglong; Zi, Yanyang; Zhang, Xinong

    2015-01-01

    This paper proposes rhombic micro-displacement amplifier (RMDA) for piezoelectric actuator (PA). First, the geometric amplification relations are analyzed and linear model is built to analyze the mechanical and electrical properties of this amplifier. Next, the accurate modeling method of amplifier is studied for important application of precise servo control. The classical Preisach model (CPM) is generally implemented using a numerical technique based on the first-order reversal curves (FORCs). The accuracy of CPM mainly depends on the number of FORCs. However, it is generally difficult to achieve enough number of FORCs in practice. So, Support Vector Machine (SVM) is employed in the work to circumvent the deficiency of the CPM. Then the hybrid model, which is based on discrete CPM and SVM is developed to account for hysteresis and dynamic effects. Finally, experimental validation is carried out. The analyzed result shows that this amplifier with the hybrid model is suitable for control application.

  6. DYNAMICS OF SI MODELS WITH BOTH HORIZONTAL AND VERTICAL TRANSMISSIONS AS WELL AS ALLEE EFFECTS*

    PubMed Central

    Kang, Yun; Castillo-Chavez, Carlos

    2014-01-01

    A general SI (Susceptible-Infected) epidemic system of host-parasite interactions operating under Allee effects, horizontal and/or vertical transmission, and where infected individuals experience pathogen-induced reductions in reproductive ability, is introduced. The initial focus of this study is on the analyses of the dynamics of Density-Dependent and Frequency-Dependent effects on SI models (SI-DD and SI-FD). The analyses identify conditions involving horizontal and vertical transmitted reproductive numbers, namely those used to characterize and contrast SI-FD and SI-DD dynamics. Conditions that lead to disease-driven extinction, or disease-free dynamics, or susceptible-free dynamics, or endemic disease patterns are identified. The SI-DD system supports richer dynamics including limit cycles while the SI-FD model only supports equilibrium dynamics. SI models under “small” horizontal transmission rates may result in disease-free dynamics. SI models under with and inefficient reproductive infectious class may lead to disease-driven extinction scenarios. The SI-DD model supports stable periodic solutions that emerge from an unstable equilibrium provided that either the Allee threshold and/or the disease transmission rate is large; or when the disease has limited influence on the infectives growth rate; and/or when disease-induced mortality is low. Host-parasite systems where diffusion or migration of local populations manage to destabilize them are examples of what is known as diffusive instability. The exploration of SI-dynamics in the presence of dispersal brings up the question of whether or not diffusive instability is a possible outcome. Here, we briefly look at such possibility within two-patch coupled SI-DD and SI-FD systems. It is shown that relative high levels of asymmetry, two modes of transmission, frequency dependence, and Allee effects are capable of supporting diffusive instability. PMID:24389426

  7. Sensitivity of snow cover to horizontal resolution in a land surface model

    NASA Astrophysics Data System (ADS)

    Dutra, E.; Kotlarski, S.; Viterbo, P.; Balsamo, G.; Miranda, P. M. A.; Schär, C.

    2010-09-01

    Snow cover is a highly variable land surface condition that exerts a strong control on the heat and moisture budget of the overlying atmosphere. Modeling studies based on long integrations of global circulation models (GCM) are normally carried out at very low resolution (typically coarser than 100 km) due to their high computational demand. On local scales, snow cover plays an important socioeconomic role, ranging from water management applications to outdoor recreation. These latter applications vary in horizontal resolution from a few hundred meters to a few kilometers, where small scale topography, land cover and local circulation effects play a significant role. In this study our focus will be on horizontal scales ranging from typical GCM global climate modeling to high resolution global weather forecasts. In the land surface component of a GCM (land surface model - LSM), snow cover temporal and spatial variability is mainly determined by the overlying atmospheric conditions. However, once snowfall settles on the ground, the sub-grid scale variability associated with complex terrain and land cover variability (not resolved at the model resolution) is parameterized following simple physical and/or empirical relations. The present study intends to access the impact of horizontal resolution in the European Centre for Medium-Range Weather Forecasts (ECMWF) land surface model (HTESSEL). HTESSEL is forced by the ECMWF operational weather forecasts since March 2006 to December 2009 (runs in offline/stand-alone mode). The control run is carried out at the horizontal resolution of the forecasts at TL799 (gaussian reduced grid N400 -about 25 km). Two lower horizontal resolutions are then tested: TL255 (gaussian reduced grid - about 80 km, same as the ERA-Interim reanalysis), and TL95 (gaussian reduced grid N48 - about 200 km). The length of the simulations is rather small (only 46 months), however global meteorological forcing at 25 km can only be accessed through the

  8. Testing fault displacement-length scaling relations through analogue modeling in an extensional setting

    NASA Astrophysics Data System (ADS)

    Bonini, L.; Basili, R.; Burrato, P.; Kastelic, V.; Toscani, G.; Seno, S.; Valensise, G.

    2013-12-01

    The scaling relation between displacement and length of faults plays a crucial role in understanding the growth history of individual faults and their possible linkage and reactivation in future ruptures. Displacement-length relations are commonly based on empirical data. The measurement of fault geometric properties, however, is generally affected by large scattering due not only to intrinsic difficulties of making observations in natural cases (outcrop availability, seismic profiles), but also to the variety of geological factors that may affect the rupture patterns. These can be the interaction between the present-day tectonic regime and an inherited structural fabric, or that between a master fault at depth and shallow structural features. As an alternative to field observations, analogue modeling provides an opportunity to investigate the faulting processes in a controlled environment. During the last decade, the ability of scaled models to properly reproduce such geological processes has greatly improved thanks to the introduction of new materials (e.g. wet kaolin) suitable for reproducing brittle deformation in the upper crust and hi-tech monitoring systems (e.g. laser scanner, particle image velocimetry) with the ability of capturing structural details and performing accurate measurements. We use a dedicated apparatus with such properties to gain insights on the evolution of extensional faults through a suite of experiments which includes (a) setups in homogeneous material to test our ability in meeting general criteria related with fault displacement-length parameters; and (b) increasing complexities attained by inserting various pre-existing fault patterns to analyze how shallow mechanical discontinuities affect our ability to characterize a major fault at depth. Our results show that pre-existing faults can either halt or favor fault development and growth depending on their location/orientation with respect to the applied stress field and suggest the

  9. Evaluation of global horizontal irradiance to plane-of-array irradiance models at locations across the United States

    SciTech Connect

    Lave, Matthew; Hayes, William; Pohl, Andrew; Hansen, Clifford W.

    2015-02-02

    We report an evaluation of the accuracy of combinations of models that estimate plane-of-array (POA) irradiance from measured global horizontal irradiance (GHI). This estimation involves two steps: 1) decomposition of GHI into direct and diffuse horizontal components and 2) transposition of direct and diffuse horizontal irradiance (DHI) to POA irradiance. Measured GHI and coincident measured POA irradiance from a variety of climates within the United States were used to evaluate combinations of decomposition and transposition models. A few locations also had DHI measurements, allowing for decoupled analysis of either the decomposition or the transposition models alone. Results suggest that decomposition models had mean bias differences (modeled versus measured) that vary with climate. Transposition model mean bias differences depended more on the model than the location. Lastly, when only GHI measurements were available and combinations of decomposition and transposition models were considered, the smallest mean bias differences were typically found for combinations which included the Hay/Davies transposition model.

  10. MOCVD of GaAs in a horizontal reactor - Modeling and growth

    NASA Technical Reports Server (NTRS)

    Clark, Ivan O.; Fox, Bradley A.; Jesser, William A.; Black, Linda R.

    1991-01-01

    A two-dimensional model for metalorganic chemical vapor deposition of GaAs in a horizontal reactor is presented. The model is characterized by the following parameters: reactor geometry and operating pressure, thermal boundary conditions, ratio of reactants, chemical reactions, total inlet gas flow rate, as well as molecular weights, thermal conductivities, heat capacities, viscosities, and binary diffusion coefficients of the gas-phase species. Film thickness profiles predicted by the model are compared with those of GaAs thin films grown in the modeled reactor. Results obtained show a good agreement between the predictions and data over the entire length of the deposition region for the low pressure and high flow rate run. Attention is also given to the reactor design and growth conditions.

  11. Sensitivity of Tsunami Waves and Coastal Inundation/Runup to Seabed Displacement Models: Application to the Cascadia Subduction zone

    NASA Astrophysics Data System (ADS)

    Jalali Farahani, R.; Fitzenz, D. D.; Nyst, M.

    2015-12-01

    Major components of tsunami hazard modeling include earthquake source characterization, seabed displacement, wave propagation, and coastal inundation/run-up. Accurate modeling of these components is essential to identify the disaster risk exposures effectively, which would be crucial for insurance industry as well as policy makers to have tsunami resistant design of structures and evacuation planning (FEMA, 2008). In this study, the sensitivity and variability of tsunami coastal inundation due to Cascadia megathrust subduction earthquake are studied by considering the different approaches for seabed displacement model. The first approach is the analytical expressions that were proposed by Okada (1985, 1992) for the surface displacements and strains of rectangular sources. The second approach was introduced by Meade (2006) who introduced analytical solutions for calculating displacements, strains, and stresses on triangular sources. In this study, the seabed displacement using triangular representation of geometrically complex fault surfaces is compared with the Okada rectangular representations for the Cascadia subduction zone. In the triangular dislocation algorithm, the displacement is calculated using superposition of two angular dislocations for each of the three triangle legs. The triangular elements could give a better and gap-free representation of the fault surfaces. In addition, the rectangular representation gives large unphysical vertical displacement along the shallow-depth fault edge that generates unrealistic short-wavelength waves. To study the impact of these two different algorithms on the final tsunami inundation, the initial tsunami wave as well as wave propagation and the coastal inundation are simulated. To model the propagation of tsunami waves and coastal inundation, 2D shallow water equations are modeled using the seabed displacement as the initial condition for the numerical model. Tsunami numerical simulation has been performed on high

  12. Energetic dynamics of a rotating horizontal convection model with wind forcing

    NASA Astrophysics Data System (ADS)

    Zemskova, Varvara; White, Brian; Scotti, Alberto

    2015-11-01

    We present a new test case for rotating horizontal convection, where the flow is driven by differential buoyancy forcing along a horizontal surface. This simple model is used to understand and quantify the influence of surface heating and cooling and wind stress on the Meridional Overturning Circulation. The domain is a rectangular basin with surface cooling at both ends (the poles) and surface warming in the middle (equatorial) region. To model the effect of the Antarctic Circumpolar Current, reentrant channel is placed near the Southern pole. Free-slip boundary conditions are imposed in the closed box, while zonally periodic boundary conditions are enforced in the channel. The problem is solved numerically using a 3D DNS model based on a finite-volume AMR solver for the Boussinesq Navier-Stokes equations with rotation. The relative contributions of surface buoyancy and wind forcing and the energetic balance are analyzed at a Rayleigh number of 108 and a relatively high aspect ratio of [5, 10, 1] in zonal, meridional and vertical directions, respectively. The overall dynamics, including large-scale overturning, baroclinic eddying, and turbulent mixing are investigated using the local Available Potential Energy framework introduced in [Scotti and White, J. Fluid Mech., 2014]. This research is part of the Blue Waters sustained-petascale computing project, supported by the NSF (awards OCI-0725070, ACI-1238993 and ACI-14-44747) and the state of Illinois.

  13. Sensitivity of the Maritime Continent precipitation to horizontal resolution in a coupled regional model

    NASA Astrophysics Data System (ADS)

    Li, Yue; Jourdain, Nicolas; Taschetto, Andréa; Gupta, Alex Sen; Masson, Sébastien; Cai, Wenju

    2015-04-01

    The Maritime Continent (MC) is centred at one of the major monsoon systems in the world. Characterized by massive tropical heating and precipitation, it is strongly influencing both the Hadley and Walker circulations. However, there are significant challenges in correctly represent climate of this region because of the complex topography and the arrangement of lands and seas. It is often argued that improved representation of the diurnal cycle over islands and the complex mesoscale circulation associated with land-sea contrast is important to energy and hydrological cycles of this region. To investigate the sensitivity of precipitation over the MC to model horizontal resolution, we perform three regional numerical experiments using the coupled NEMO-OASIS-WRF model at different horizontal resolutions of 3/4°, 1/4° and 1/12° in both atmosphere and ocean components. The 3/4° and 1/4° experiments are run on a large MC domain for 21 years (1989 to 2009), and the 1/12° experiment is nested within the 1/4° domain using two-way interactive nesting over 5 years. Increasing the resolution reduces biases in mean SST and mean precipitation. The precipitation distribution is also improved at higher resolution, particularly in coastal areas. A part of these improvements are related to different behaviours of the model physical schemes across the three resolutions. Other changes are interpreted in terms of land-sea breeze, that we describe through a new comprehensive method.

  14. Approximation for Horizontal Photon Transport in Cloud Remote Sensing Problems

    NASA Technical Reports Server (NTRS)

    Plantnick, Steven

    1999-01-01

    The effect of horizontal photon transport within real-world clouds can be of consequence to remote sensing problems based on plane-parallel cloud models. An analytic approximation for the root-mean-square horizontal displacement of reflected and transmitted photons relative to the incident cloud-top location is derived from random walk theory. The resulting formula is a function of the average number of photon scatterings, and particle asymmetry parameter and single scattering albedo. In turn, the average number of scatterings can be determined from efficient adding/doubling radiative transfer procedures. The approximation is applied to liquid water clouds for typical remote sensing solar spectral bands, involving both conservative and non-conservative scattering. Results compare well with Monte Carlo calculations. Though the emphasis is on horizontal photon transport in terrestrial clouds, the derived approximation is applicable to any multiple scattering plane-parallel radiative transfer problem. The complete horizontal transport probability distribution can be described with an analytic distribution specified by the root-mean-square and average displacement values. However, it is shown empirically that the average displacement can be reasonably inferred from the root-mean-square value. An estimate for the horizontal transport distribution can then be made from the root-mean-square photon displacement alone.

  15. Pore invasion dynamics during fluid front displacement - an interfacial front model

    NASA Astrophysics Data System (ADS)

    Moebius, F.; Or, D.

    2013-12-01

    The dynamics of fluid fronts in porous media shape subsequent phase distribution and the transport properties of the partially saturated region with implications ranging from gaseous transport to plant roots to extraction or injection of fluids to petroleum reservoirs. What macroscopically seems as a smooth and continuous motion of a displacement fluid front, involves numerous rapid pore-scale interfacial jumps often resembling avalanches of invasion events. We present a 2D model for simulating interfacial front displacement that was developed to study details of invasion dynamics at the front and to systematically study effects of boundary conditions on the resulting macroscopic properties after passage of a front. The interfacial front is represented by hydraulically connected sinusoidal capillaries allowing for redistribution and capillary pressure relaxation through exchange with neighboring interfaces. The model focuses on processes at the front and neglects interfacial redistribution left behind the front as well as saturated fluid flow below the front. The description of the dynamics of the rapid non-wetting fluid invasions induced by constant wetting fluid withdrawal includes capillary, viscous and hydrostatic component and inertia. Results show that the additional inertial force (not considered in previous studies) does significantly affect invasion pathways such as the hypothesized 'consecutive jumps'. The menisci jump velocities show a strong relation to geometrical throat dimensions that reflect local capillary gradients. The front model further enables to link boundary conditions (macroscopic Capillary number, throat size distribution) effects on pore invasion sequences and impact on residual wetting phase entrapment and front morphology. A limited comparison of model predictions with experimental results from sintered glass-beads micro-models will be presented.

  16. On mixed and displacement finite element models of a refined shear deformation theory for laminated anisotropic plates

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1986-01-01

    An improved plate theory that accounts for the transverse shear deformation is presented, and mixed and displacement finite element models of the theory are developed. The theory is based on an assumed displacement field in which the inplane displacements are expanded in terms of the thickness coordinate up to the cubic term and the transverse deflection is assumed to be independent of the thickness coordinate. The governing equations of motion for the theory are derived from the Hamilton's principle. The theory eliminates the need for shear correction factors because the transverse shear stresses are represented parabolically. A mixed finite element model that uses independent approximations of the displacements and moments, and a displacement model that uses only displacements as degrees of freedom are developed. A comparison of the numerical results for bending with the exact solutions of the new theory and the three-dimensional elasticity theory shows that the present theory (and hence the finite element models) is more accurate than other plate-theories of the same order.

  17. Modelling Viscoelastic Behaviour of Polymer by A Mixed Velocity, Displacement Formulation - Numerical and Experimental Results

    SciTech Connect

    Pham, VT.; Silva, L.; Digonnet, H.; Combeaud, C.; Billon, N.; Coupez, T.

    2011-05-04

    The objective of this work is to model the viscoelastic behaviour of polymer from the solid state to the liquid state. With this objective, we perform experimental tensile tests and compare with simulation results. The chosen polymer is a PMMA whose behaviour depends on its temperature. The computation simulation is based on Navier-Stokes equations where we propose a mixed finite element method with an interpolation P1+/P1 using displacement (or velocity) and pressure as principal variables. The implemented technique uses a mesh composed of triangles (2D) or tetrahedra (3D). The goal of this approach is to model the viscoelastic behaviour of polymers through a fluid-structure coupling technique with a multiphase approach.

  18. Four-beam model for vibration analysis of a cantilever beam with an embedded horizontal crack

    NASA Astrophysics Data System (ADS)

    Liu, Jing; Zhu, Weidong; Charalambides, Panos G.; Shao, Yimin; Xu, Yongfeng; Wu, Kai; Xiao, Huifang

    2016-01-01

    As one of the main failure modes, embedded cracks occur in beam structures due to periodic loads. Hence it is useful to investigate the dynamic characteristics of a beam structure with an embedded crack for early crack detection and diagnosis. A new four-beam model with local flexibilities at crack tips is developed to investigate the transverse vibration of a cantilever beam with an embedded horizontal crack; two separate beam segments are used to model the crack region to allow opening of crack surfaces. Each beam segment is considered as an Euler-Bernoulli beam. The governing equations and the matching and boundary conditions of the four-beam model are derived using Hamilton's principle. The natural frequencies and mode shapes of the four-beam model are calculated using the transfer matrix method. The effects of the crack length, depth, and location on the first three natural frequencies and mode shapes of the cracked cantilever beam are investigated. A continuous wavelet transform method is used to analyze the mode shapes of the cracked cantilever beam. It is shown that sudden changes in spatial variations of the wavelet coefficients of the mode shapes can be used to identify the length and location of an embedded horizontal crack. The first three natural frequencies and mode shapes of a cantilever beam with an embedded crack from the finite element method and an experimental investigation are used to validate the proposed model. Local deformations in the vicinity of the crack tips can be described by the proposed four-beam model, which cannot be captured by previous methods.

  19. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE PAGESBeta

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  20. Electron–phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Béland, L. K.; Stocks, G. M.; Stoller, R. E.

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  1. Character displacement and the evolution of niche complementarity in a model biofilm community.

    PubMed

    Ellis, Crystal N; Traverse, Charles C; Mayo-Smith, Leslie; Buskirk, Sean W; Cooper, Vaughn S

    2015-02-01

    Colonization of vacant environments may catalyze adaptive diversification and be followed by competition within the nascent community. How these interactions ultimately stabilize and affect productivity are central problems in evolutionary ecology. Diversity can emerge by character displacement, in which selection favors phenotypes that exploit an alternative resource and reduce competition, or by facilitation, in which organisms change the environment and enable different genotypes or species to become established. We previously developed a model of long-term experimental evolution in which bacteria attach to a plastic bead, form a biofilm, and disperse to a new bead. Here, we focus on the evolution of coexisting mutants within a population of Burkholderia cenocepacia and how their interactions affected productivity. Adaptive mutants initially competed for space, but later competition declined, consistent with character displacement and the predicted effects of the evolved mutations. The community reached a stable equilibrium as each ecotype evolved to inhabit distinct, complementary regions of the biofilm. Interactions among ecotypes ultimately became facilitative and enhanced mixed productivity. Observing the succession of genotypes within niches illuminated changing selective forces within the community, including a fundamental role for genotypes producing small colony variants that underpin chronic infections caused by B. cenocepacia. PMID:25494960

  2. Electron-phonon coupling in Ni-based binary alloys with application to displacement cascade modeling.

    PubMed

    Samolyuk, G D; Béland, L K; Stocks, G M; Stoller, R E

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron-phonon (el-ph) coupling. The el-ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el-ph coupling. Thus, the el-ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10-20% in the alloys under consideration. PMID:27033732

  3. Character displacement and the evolution of niche complementarity in a model biofilm community

    PubMed Central

    Ellis, Crystal N; Traverse, Charles C; Mayo-Smith, Leslie; Buskirk, Sean W; Cooper, Vaughn S

    2015-01-01

    Colonization of vacant environments may catalyze adaptive diversification and be followed by competition within the nascent community. How these interactions ultimately stabilize and affect productivity are central problems in evolutionary ecology. Diversity can emerge by character displacement, in which selection favors phenotypes that exploit an alternative resource and reduce competition, or by facilitation, in which organisms change the environment and enable different genotypes or species to become established. We previously developed a model of long-term experimental evolution in which bacteria attach to a plastic bead, form a biofilm, and disperse to a new bead. Here, we focus on the evolution of coexisting mutants within a population of Burkholderia cenocepacia and how their interactions affected productivity. Adaptive mutants initially competed for space, but later competition declined, consistent with character displacement and the predicted effects of the evolved mutations. The community reached a stable equilibrium as each ecotype evolved to inhabit distinct, complementary regions of the biofilm. Interactions among ecotypes ultimately became facilitative and enhanced mixed productivity. Observing the succession of genotypes within niches illuminated changing selective forces within the community, including a fundamental role for genotypes producing small colony variants that underpin chronic infections caused by B. cenocepacia. PMID:25494960

  4. Tsunami simulation using submarine displacement calculated from simulation of ground motion due to seismic source model

    NASA Astrophysics Data System (ADS)

    Akiyama, S.; Kawaji, K.; Fujihara, S.

    2013-12-01

    Since fault fracturing due to an earthquake can simultaneously cause ground motion and tsunami, it is appropriate to evaluate the ground motion and the tsunami by single fault model. However, several source models are used independently in the ground motion simulation or the tsunami simulation, because of difficulty in evaluating both phenomena simultaneously. Many source models for the 2011 off the Pacific coast of Tohoku Earthquake are proposed from the inversion analyses of seismic observations or from those of tsunami observations. Most of these models show the similar features, which large amount of slip is located at the shallower part of fault area near the Japan Trench. This indicates that the ground motion and the tsunami can be evaluated by the single source model. Therefore, we examine the possibility of the tsunami prediction, using the fault model estimated from seismic observation records. In this study, we try to carry out the tsunami simulation using the displacement field of oceanic crustal movements, which is calculated from the ground motion simulation of the 2011 off the Pacific coast of Tohoku Earthquake. We use two fault models by Yoshida et al. (2011), which are based on both the teleseismic body wave and on the strong ground motion records. Although there is the common feature in those fault models, the amount of slip near the Japan trench is lager in the fault model from the strong ground motion records than in that from the teleseismic body wave. First, the large-scale ground motion simulations applying those fault models used by the voxel type finite element method are performed for the whole eastern Japan. The synthetic waveforms computed from the simulations are generally consistent with the observation records of K-NET (Kinoshita (1998)) and KiK-net stations (Aoi et al. (2000)), deployed by the National Research Institute for Earth Science and Disaster Prevention (NIED). Next, the tsunami simulations are performed by the finite

  5. Regional Climate Modelling: impact of horizontal grid resolution on precipitation estimates over Ireland

    NASA Astrophysics Data System (ADS)

    McGrath, Ray; Nolan, Paul

    2016-04-01

    Regional Climate Models (RCMs) are widely used to dynamically downscale the outputs from global climate model simulations. There is some evidence that high resolution RCMs with explicit convection can provide more accurate information on extreme precipitation events compared to coarse resolution simulations with parameterized convection. In flooding applications, where the interest may be focused on precipitation over a relatively large river catchment area, compared to the model grid spacing, the value of enhanced resolution needs to be quantified. This is addressed in a study using two RCMs: the COnsortium for Small-scale Modeling-Climate Limited-area Modelling (COSMO-CLM) model (version CCLM_5.00) and the Weather Research and Forecasting (WRF) model (version 3.7.1). Using ERA-Interim global re-analysis data as boundaries, climate simulations were performed for the period 1981-2015, for an area focused on Ireland, using model horizontal grid spacings of 18, 6 and 2 km (WRF) and 18, 6 and 1.5 km (COSMO-CLM). Model hourly precipitation outputs were compared with gridded and point observational datasets for time intervals extending from hours to seasons to assess the performance of the RCMs at the different resolutions.

  6. Horizontal annular flow modelling using a compositional based interface capturing approach

    NASA Astrophysics Data System (ADS)

    Pavlidis, Dimitrios; Xie, Zhizhua; Percival, James; Gomes, Jefferson; Pain, Chris; Matar, Omar

    2014-11-01

    Progress on a consistent approach for interface-capturing in which each component represents a different phase/fluid is described. The aim is to develop a general multi-phase modelling approach based on fully-unstructured meshes that can exploit the latest mesh adaptivity methods, and in which each fluid phase may have a number of components. The method is compared against experimental results for a collapsing water column test case and a convergence study is performed. A number of numerical test cases are undertaken to demonstrate the method's ability to model arbitrary numbers of phases with arbitrary equations of state. The method is then used to simulate horizontal annular flows. EPSRC Programme Grant, MEMPHIS, EP/K0039761/1.

  7. Development of a model counter-rotating type horizontal-axis tidal turbine

    NASA Astrophysics Data System (ADS)

    Huang, B.; Yoshida, K.; Kanemoto, T.

    2016-05-01

    In the past decade, the tidal energies have caused worldwide concern as it can provide regular and predictable renewable energy resource for power generation. The majority of technologies for exploiting the tidal stream energy are based on the concept of the horizontal axis tidal turbine (HATT). A unique counter-rotating type HATT was proposed in the present work. The original blade profiles were designed according to the developed blade element momentum theory (BEMT). CFD simulations and experimental tests were adopted to the performance of the model counter-rotating type HATT. The experimental data provides an evidence of validation of the CFD model. Further optimization of the blade profiles was also carried out based on the CFD results.

  8. Neutrinos in a left-right model with a horizontal symmetry

    NASA Astrophysics Data System (ADS)

    Kiers, Ken; Assis, Michael; Simons, David; Petrov, Alexey A.; Soni, Amarjit

    2006-02-01

    We analyze the lepton sector of a left-right model based on the gauge group SU(2)L×SU(2)R×U(1), concentrating mainly on neutrino properties. Using the seesaw mechanism and a horizontal symmetry, we keep the right-handed symmetry breaking scale relatively low, while simultaneously satisfying phenomenological constraints on the light neutrino masses. We take the right-handed scale to be of order 10’s of TeV and perform a full numerical analysis of the model’s parameter space, subject to experimental constraints on neutrino masses and mixings. The numerical procedure yields results for the right-handed neutrino masses and mixings and the various CP-violating phases. We also discuss phenomenological applications of the model to neutrinoless double beta decay, lepton-flavor-violating decays (including decays such as τ→3μ) and leptogenesis.

  9. Hydromechanical modeling of pulse tests that measure both fluidpressure and fracture-normal displacement of the Coaraze Laboratory site,France

    SciTech Connect

    Cappa, F.; Guglielmi, Y.; Rutqvist, J.; Tsang, C-F.; Thoraval, A.

    2006-04-22

    In situ fracture mechanical deformation and fluid flowinteractions are investigated through a series of hydraulic pulseinjection tests, using specialized borehole equipment that cansimultaneously measure fluid pressure and fracture displacements. Thetests were conducted in two horizontal boreholes spaced one meter apartvertically and intersecting a near-vertical highly permeable faultlocated within a shallow fractured carbonate rock. The field data wereevaluated by conducting a series of coupled hydromechanical numericalanalyses, using both distinct-element and finite-element modelingtechniques and both two- and three-dimensional model representations thatcan incorporate various complexities in fracture network geometry. Oneunique feature of these pulse injection experiments is that the entiretest cycle, both the initial pressure increase and subsequent pressurefall-off, is carefully monitored and used for the evaluation of the insitu hydromechanical behavior. Field test data are evaluated by plottingfracture normal displacement as a function of fluid pressure, measured atthe same borehole. The resulting normal displacement-versus-pressurecurves show a characteristic loop, in which the paths for loading(pressure increase) and unloading (pressure decrease) are different. Bymatching this characteristic loop behavior, the fracture normal stiffnessand an equivalent stiffness (Young's modulus) of the surrounding rockmass can be back-calculated. Evaluation of the field tests by couplednumerical hydromechanical modeling shows that initial fracture hydraulicaperture and normal stiffness vary by a factor of 2 to 3 for the twomonitoring points within the same fracture plane. Moreover, the analysesshow that hydraulic aperture and the normal stiffness of the pulse-testedfracture, the stiffness of surrounding rock matrix, and the propertiesand geometry of the surrounding fracture network significantly affectcoupled hydromechanical responses during the pulse injection test

  10. Cancer Progression Mediated by Horizontal Gene Transfer in an In Vivo Model

    PubMed Central

    Trejo-Becerril, Catalina; Pérez-Cárdenas, Enrique; Taja-Chayeb, Lucía; Anker, Philippe; Herrera-Goepfert, Roberto; Medina-Velázquez, Luis A.; Hidalgo-Miranda, Alfredo; Pérez-Montiel, Delia; Chávez-Blanco, Alma; Cruz-Velázquez, Judith; Díaz-Chávez, José; Gaxiola, Miguel; Dueñas-González, Alfonso

    2012-01-01

    It is known that cancer progresses by vertical gene transfer, but this paradigm ignores that DNA circulates in higher organisms and that it is biologically active upon its uptake by recipient cells. Here we confirm previous observations on the ability of cell-free DNA to induce in vitro cell transformation and tumorigenesis by treating NIH3T3 recipient murine cells with serum of colon cancer patients and supernatant of SW480 human cancer cells. Cell transformation and tumorigenesis of recipient cells did not occur if serum and supernatants were depleted of DNA. It is also demonstrated that horizontal cancer progression mediated by circulating DNA occurs via its uptake by recipient cells in an in vivo model where immunocompetent rats subjected to colon carcinogenesis with 1,2-dimethylhydrazine had increased rate of colonic tumors when injected in the dorsum with human SW480 colon carcinoma cells as a source of circulating oncogenic DNA, which could be offset by treating these animals with DNAse I and proteases. Though the contribution of biologically active molecules other than DNA for this phenomenon to occur cannot be ruled out, our results support the fact that cancer cells emit into the circulation biologically active DNA to foster tumor progression. Further exploration of the horizontal tumor progression phenomenon mediated by circulating DNA is clearly needed to determine whether its manipulation could have a role in cancer therapy. PMID:23285175

  11. The horizontal planar structure of kinetic energy in a model vertical-axis wind turbine array

    NASA Astrophysics Data System (ADS)

    Craig, Anna; Zeller, Robert; Zarama, Francisco; Weitzman, Joel; Dabiri, John; Koseff, Jeffrey

    2013-11-01

    Recent studies have indicated that arrays of vertical axis wind turbines (VAWTs) could potentially harvest significantly more power per unit land area than arrays composed of conventional horizontal axis wind turbines. However, to design VAWT arrays for optimal power conversion, a more comprehensive understanding of inter-turbine energy transfer is needed. In the presented study, a geometrically scaled array of rotating circular cylinders is used to model a VAWT array. The horizontal inter-cylinder mean fluid velocities and Reynolds stresses are measured on several cross-sections using 2D particle image velocimetry in a flume. Two orientations of the array relative to the incoming flow are tested. The results indicate that cylinder rotation drives asymmetric mean flow patterns within and above the array, resulting in non-uniform distributions of turbulent kinetic energy. The variability is observed to be directly related to the ratio of the cylinder rotation speed to the streamwise water velocity. Emphasis is placed on the implications of the asymmetries for power production. Work supported by a Stanford Graduate Fellowship to A.E.C, by funding to J.O.D. from ONR N000141211047 and the Gordon and Betty Moore Foundation through Grant GBMF2645, and by funding from the Environmental Fluid Mechanics Laboratory, Stanford University.

  12. A finite element model of remote palpation of breast lesions using radiation force: factors affecting tissue displacement.

    PubMed

    Nightingale, K R; Nightingale, R W; Palmeri, M L; Trahey, G E

    2000-01-01

    The early detection of breast cancer reduces patient mortality. The most common method of breast cancer detection is palpation. However, lesions that lie deep within the breast are difficult to palpate when they are small. Thus, a method of remote palpation, which may allow the detection of small lesions lying deep within the breast, is currently under investigation. In this method, acoustic radiation force is used to apply localized forces within tissue (to tissue volumes on the order of 2 mm3) and the resulting tissue displacements are mapped using ultrasonic correlation based methods. A volume of tissue that is stiffer than the surrounding medium (i.e., a lesion) distributes the force throughout the tissue beneath it, resulting in larger regions of displacement, and smaller maximum displacements. The resulting displacement maps may be used to image tissue stiffness. A finite-element-model (FEM) of acoustic remote palpation is presented in this paper. Using this model, a parametric analysis of the affect of varying tissue and acoustic beam characteristics on radiation force induced tissue displacements is performed. The results are used to evaluate the potential of acoustic remote palpation to provide useful diagnostic information in a clinical setting. The potential for using a single diagnostic transducer to both generate radiation force and track the resulting displacements is investigated. PMID:10823496

  13. Coupled ocean-atmosphere modeling on horizontally icosahedral and vertically hybrid-isentropic/isopycnic grids.

    NASA Astrophysics Data System (ADS)

    Bleck, Rainer; Sun, Shan; Li, Haiqin; Benjamin, Stan

    2016-04-01

    Current efforts to close the gap between weather prediction and climate models have led to the construction of a coupled ocean-atmosphere system consisting of two high-resolution component models, operating on matching icosahedral grids and utilizing adaptive, near-isentropic/isopycnic vertical coordinates. The two components models, FIM and HYCOM (the latter converted to an icosahedral mesh for this purpose), have been tested extensively in twice-daily global medium-range weather prediction (http://fim.noaa.gov) and in real-time ocean data assimilation (http://hycom.org), respectively. The use of matching horizontal grids, currently at resolutions of 15km, 30km and 60km, avoids coastline ambiguities and interpolation errors at the air-sea interface. The intended purpose of the coupled model being subseasonal-to-seasonal prediction, our focus is on mid-term precipitation biases and the statistical steadiness of the atmospheric circulation (blocking frequency, Rossby wave breaking, meridional heat transport, etc.), as well as on possible causes of ocean model drift. An attempt is made to isolate the weather model's role in modifying water mass properties and ocean circulations (including meridional overturning) by comparing coupled model results to ocean-only experiments forced by observed atmospheric boundary conditions. A multi-decadal run at 60km resolution is used to illustrate ENSO variability in the coupled system.

  14. Modelling coastal low-level wind-jets: does horizontal resolution matter?

    NASA Astrophysics Data System (ADS)

    Ranjha, Raza; Tjernström, Michael; Svensson, Gunilla; Semedo, Alvaro

    2016-04-01

    Atmospheric flows in coastal regions are impacted by land-sea temperature contrasts, complex terrain, shape of the coastline, among many things. Along the west coast of central North America, winds in the boundary layer are mainly from north or northwest, roughly parallel to the coastline. Frequently, the coastal low-level wind field is characterized by a sharp wind maximum along the coast in the lowest kilometre. This feature, commonly referred to as a coastal low-level jet (CLLJ), has significant impact on the climatology of the coastal region and affects many human activities in the littoral zone. Hence, a good understanding and forecasting of CLLJs are vital. This study evaluates the issue of proper mesoscale numerical model resolution to describe the physics of a CLLJ, and its impact on the upper ocean. The COAMPS® model is used for a summer event to determine the realism of the model results compared to observations, from an area of supercritical flow adjustment between Pt. Sur and Pt. Conception, California. Simulations at different model horizontal resolutions, from 54 to 2 km are performed. While the model produces realistic results with increasing details at higher resolution, the results do not fully converge even at a resolution of only few kilometres and an objective analysis of model errors do not show an increased skill with increasing resolution. Based on all available information, a compromise resolution appears to be at least 6 km. New methods may have to be developed to evaluate models at very high resolution.

  15. Using Microfluidics for Visualisation of Displacement Mechanisms on Pore Network Models

    NASA Astrophysics Data System (ADS)

    Gerami Kaviri Nejad, A.; Mostaghimi, P.; Armstrong, R. T.; Rafeie, M.; Ebrahimi Warkiani, M.

    2015-12-01

    We use microfluidic methods for studying displacement mechanisms of immiscible fluids including drainage and imbibition in porous media at the pore scale. We use soft lithography method to make 4' diameter silicon wafer to be used as a mould of our designs. We have fabricated a range of microfluidic chips based on a range of patterns including pore junction with unequal throats, junction of throats with different coordination numbers, and junction of tortuous throats. We also fabricate more complex networks as a combination of the mentioned simple patterns. Decane and water are used as the wetting and non-wetting phases, respectively. Using high-resolution microscopy, we visualise the displacement processes and the movement of the interface between two fluids at different saturations. We initially test to micromodel chip for modelling drainage into a pore junction and compare our results with the prediction by the Young-Laplace equations. Then we focus on the sequence of pore filling and effects of pore space geometry, tortuosity and the injection rate. We use plasma treating to vary the contact angle and then study the effects of wettability on interface movement. Using accurate pump and pressure controller, we measure pressure drop across the micromodels at different time. By image processing of fluids distribution in the microfluidic chip, saturation of both phases can be estimated. Then, we plot relative permeability versus saturation curves for different pore space geometries. Our results can be used for validation of numerical two phase flow simulation and also we provide novel suggestions for modifying the equations of motion in pore network models.

  16. Flow Visualization Study of a 1/48-Scale AFTI/F111 Model to Investigate Horizontal Tail Flow Disturbances

    NASA Technical Reports Server (NTRS)

    Bjarke, Lisa J.

    1991-01-01

    During flight testing of the AFTI/F111 aircraft, horizontal tail buffet was observed. Flutter analysis ruled out any aeroelastic instability, so a water-tunnel flow visualization study was conducted to investigate possible flow disturbances on the horizontal tail which might cause buffet. For this study, a 1/48-scale model was used. Four different wing cambers and one horizontal tail setting were tested between 0 and 20 deg angle of attack. These wing cambers corresponded to the following leading training edge deflections: 0/2, 10/10, 10/2, and 0/10. Flow visualization results in the form of still photographs are presented for each of the four wing cambers between 8 and 12 deg angle of attack. In general, the horizontal tail experiences flow disturbances which become more pronounced with angle of attack or wing trailing-edge deflection.

  17. Influence of Reynolds number on performance modeling of horizontal axis wind rotors

    SciTech Connect

    Musial, W.D.; Cromack, D.E.

    1988-05-01

    This paper investigates the influence of Reynolds number on performance modeling of horizontal axis wind rotors. A procedure for accounting for Reynolds number effects on airfoil section models was developed and implemented for NACA 0012 and NACA 4415 profiles; both of these models is valid through angles of attack up to 90 deg and for Reynolds numbers ranging from 4 x 10/sup 4/ to 3 x 10/sup 6/. These models were incorporated into both a lifting line computer code, LL200R, adapted for this report. This enabled greater uncertainty to be obtained in evaluating theoretical performance codes with respect to actual data, as well as providing a means by which a parametric analysis of the relative effects of Re changes on rotor performance to be performed. The use of low Reynolds number section data was found to significantly lower the predicted values of power coefficient, particularly at off-design tip speed-ratios. For symmetrical airfoils, this effect on performance was only significant for low tip-speed- ratios, while cambered airfoils were affected more uniformly at all operating conditions. Changes in performance were induced by parametric variations of wind speed, rotor scale, and rotor generating mode using the Reynolds number dependent section models. Results show that wind speed variations are more significant for smaller rotors at lower wind-speeds, and section models represented at only a single Reynolds number are more suitable for the analysis of constant RPM rotors.

  18. Tunable beam displacer

    SciTech Connect

    Salazar-Serrano, Luis José; Valencia, Alejandra; Torres, Juan P.

    2015-03-15

    We report the implementation of a tunable beam displacer, composed of a polarizing beam splitter (PBS) and two mirrors, that divides an initially polarized beam into two parallel beams whose separation can be continuously tuned. The two output beams are linearly polarized with either vertical or horizontal polarization and no optical path difference is introduced between them. The wavelength dependence of the device as well as the maximum separation between the beams achievable is limited mainly by the PBS characteristics.

  19. Muon anomalous magnetic moment and positron excess at AMS-02 in a gauged horizontal symmetric model

    NASA Astrophysics Data System (ADS)

    Tomar, Gaurav; Mohanty, Subhendra

    2014-11-01

    We studied an extension of the standard model with a fourth generation of fermions to explain the discrepancy in the muon ( g -2) and explain the positron excess seen in the AMS-02 experiment. We introduce a gauged SU(2)HV horizontal symmetry between the muon and the 4th generation lepton families. The 4th generation right-handed neutrino is identified as the dark matter with mass ~ 700GeV. The dark matter annihilates only to ( μ + μ -) and ( ν {/μ C } ν μ ) states via SU(2)HV gauge boson. The SU(2)HV gauge boson with mass ~ 1.4 TeV gives an adequate contribution to the ( g - 2) of muon and fulfill the experimental constraint from BNL measurement. The higgs production constraints from 4th generation fermions is evaded by extending the higgs sector.

  20. Penetration of sunlight into a canopy - Explicit models based on vertical and horizontal leaf projections

    NASA Technical Reports Server (NTRS)

    Otterman, J.; Brakke, T.

    1986-01-01

    The projections of leaf areas onto a horizontal plane and onto a vertical plane are examined for their utility in characterizing canopies for sunlight penetration (direct beam only) models. These projections exactly specify the penetration if the projections on the principal plane of the normals to the top surfaces of the leaves are in the same quadrant as the sun. Inferring the total leaf area from these projections (and therefore the penetration as a function of the total leaf area) is possible only with a large uncertainty (up to + or - 32 percent) because the projections are a specific measure of the total leaf area only if the leaf angle distribution is known. It is expected that this uncertainty could be reduced to more acceptable levels by making an approximate assessment of whether the zenith angle distribution is that of an extremophile canopy.

  1. Numerical modelling of resolution and sensitivity of ERT in horizontal boreholes

    NASA Astrophysics Data System (ADS)

    Danielsen, Berit E.; Dahlin, Torleif

    2010-03-01

    Resistivity in horizontal boreholes can give useful detailed information about the geological conditions for construction in rock, i.e. in front of a tunnel bore machine. This paper is an attempt to identify a suitable methodology for an effective measuring routine for this type of geophysical measurements under actual construction site conditions. Prior to any measurements numerical modelling was done in order to evaluate the resolution of different electrode arrays. Four different arrays were tested; dipole-pole, cross-hole dipole-dipole, cross-hole pole-tripole and multiple gradient array. Additionally the resolution of a combination of cross-hole dipole-dipole and multiple gradient was assessed. The 2D sensitivity patterns for various arrangements of the cross-hole dipole-dipole and multiple gradient array were examined. The sensitivity towards inaccurate borehole geometry and the influence of water in the boreholes were also investigated. Based on the model study the cross-hole dipole-dipole array, multiple gradient array and a combination of these were found to give the best result and therefore were used for test measurements in horizontal boreholes. The boreholes were 28.5 m long and drilled 6.5 m apart. Prototypes of semi-rigid borehole cables made it possible to insert multi electrode cables in an efficient way, allowing fast measurement routines. These measurements were then studied to determine their accuracy and applicability. The results showed a high resistivity rock mass at the site. A transition from high resistivity to slightly lower resistivity coincides well with a change in lithology from gneiss-granite to gneiss. It is likely that the shotcrete on the tunnel wall is seen as a low resistivity zone. The measurements are a valuable tool, but further development of the cables and streamlining of measuring routines have to be performed before the resistivity tomography can be used routinely in pilot holes during construction in rocks.

  2. Cuttings-liquid frictional pressure loss model for horizontal narrow annular flow with rotating drillpipe

    NASA Astrophysics Data System (ADS)

    Ofei, T. N.; Irawan, S.; Pao, W.

    2015-04-01

    During oil and gas drilling operations, frictional pressure loss is experienced as the drilling fluid transports the drilled cuttings from the bottom-hole, through the annulus, to the surface. Estimation of these pressure losses is critical when designing the drilling hydraulic program. Two-phase frictional pressure loss in the annulus is very difficult to predict, and even more complex when there is drillpipe rotation. Accurate prediction will ensure that the correct equivalent circulating density (ECD) is applied in the wellbore to prevent formation fracture, especially in formations with narrow window between the pore pressure and fracture gradient. Few researchers have attempted to propose cuttings-liquid frictional pressure loss models, nevertheless, these models fail when they are applied to narrow wellbores such as in casing- while-drilling and slimhole applications. This study proposes improved cuttings-liquid frictional pressure loss models for narrow horizontal annuli with drillpipe rotation using Dimensional Analysis. Both Newtonian and non-Newtonian fluids were considered. The proposed model constants were fitted by generated data from a full-scale simulation study using ANSYS-CFX. The models showed improvement over existing cuttings-liquid pressure loss correlations in literature.

  3. A dynamical model for reflex activated head movements in the horizontal plane

    NASA Technical Reports Server (NTRS)

    Peng, G. C.; Hain, T. C.; Peterson, B. W.

    1996-01-01

    We present a controls systems model of horizontal-plane head movements during perturbations of the trunk, which for the first time interfaces a model of the human head with neural feedback controllers representing the vestibulocollic (VCR) and the cervicocollic (CCR) reflexes. This model is homeomorphic such that model structure and parameters are drawn directly from anthropomorphic, biomechanical and physiological studies. Using control theory we analyzed the system model in the time and frequency domains, simulating neck movement responses to input perturbations of the trunk. Without reflex control, the head and neck system produced a second-order underdamped response with a 5.2 dB resonant peak at 2.1 Hz. Adding the CCR component to the system dampened the response by approximately 7%. Adding the VCR component dampened head oscillations by 75%. The VCR also improved low-frequency compensation by increasing the gain and phase lag, creating a phase minimum at 0.1 Hz and a phase peak at 1.1 Hz. Combining all three components (mechanics, VCR and CCR) linearly in the head and neck system reduced the amplitude of the resonant peak to 1.1 dB and increased the resonant frequency to 2.9 Hz. The closed loop results closely fit human data, and explain quantitatively the characteristic phase peak often observed.

  4. Nitrogen transformation in horizontal subsurface flow constructed wetlands I: Model development

    NASA Astrophysics Data System (ADS)

    Mayo, A. W.; Bigambo, T.

    In this paper a mathematical model for prediction of nitrogen transformation in horizontal subsurface flow constructed wetlands was developed. Two horizontal subsurface flow constructed wetlands were designed to receive organic loading rate below 50 kg/ha/d and hydraulic loading rate of 480 m 3/ha/d from a primary facultative pond. Two rectangular shaped units each 11.0 m long, 3.7 m wide and 1.0 m deep and bottom slope of 1% were constructed and filled with 6-25 mm diameter gravel pack to a depth of 0.75 m. Each unit was planted with Phragmites mauritianus with an initial plant density of 29,000 plants/ha. The plants were allowed to grow for about four months before sampling for water quality parameters commenced. Samples were collected daily for about three months. Dissolved oxygen, pH and temperature were measured in situ and ammonia, total Kjeldahl nitrogen, nitrates, nitrite and Chemical Oxygen Demand were measured in the laboratory in accordance with Standard Methods. The mathematical model took into account activities of biomass suspended in the water body and biofilm on aggregates and plant roots. The state variables modelled include organic, ammonia, and nitrate-nitrogen, which were sectored in water, plant and aggregates. The major nitrogen transformation processes considered in this study were mineralization, nitrification, denitrification, plant uptake, plant decaying, and sedimentation. The forcing functions, which were considered in the model, are temperature, pH and dissolved oxygen. Stella II software was used to simulate the nitrogen processes influencing the removal of nitrogen in the constructed wetland. One of the two-wetland units was used for model calibration and the second unit for model validation. The model results indicated that 0.872 gN/m 2 d was settled at the bottom of the wetland and on gravel bed and roots of the plants. However, 0.752 gN/m 2 d (86.2%) of the settled nitrogen was regenerated back to the water body, which means that

  5. A model of navigation-induced currents in inland waterways and implications for juvenile fish displacement.

    PubMed

    Wolter, Christian; Arlinghaus, Robert; Sukhodolov, Alexander; Engelhardt, Christof

    2004-11-01

    The likely extension of commercial inland navigation in the future could increase hazards directly impacting on the nurseries of freshwater fish, especially for smaller individuals with limited swimming abilities. One limitation of the evaluation of inland navigation on fish assemblages is the lack of suitable hydraulic models. This article presents a hydraulic model to assess the increase of navigation-induced physical forces due to higher vessel speed, length, and drought in a low-flowing waterway related to maximum swimming performance of fish to (1) foresee hazards of enhancement of inland navigation, (2) derive construction measures to minimize the hydraulic impact on small fish, and (3) improve fish recruitment in waterways. The derived model computed current velocities induced by passing commercial vessels in inland waterways experimentally verified and parameterized in a German lowland waterway. Results were linked with a model of maximum fish swimming performance to elucidate consequences for freshwater fish populations. The absolute magnitude of navigation-induced current limits the availability of littoral habitats for small fish. Typical navigation-induced current velocities of 0.7-1 m/s in the straight reaches of waterways will be maintained by fish longer than 42 mm only. Smaller juveniles unable to withstand those currents could become washed out, injured, or displaced. In contrast, in small local bays, the navigation-induced current declined significantly. According to our model, in a 20-m extended bay, the return current drops below 0.11 m/s, corresponding to the maximum swimming speed of a 9-mm-long fish. Thus, enhancing shoreline development by connecting oxbows, tributaries, and especially by purpose-built bays limits the impact on fish recruitment without restricting navigation resulting in more precautionary and sustainable inland navigation. PMID:15549651

  6. Velocity and displacement statistics in a stochastic model of nonlinear friction showing bounded particle speed.

    PubMed

    Menzel, Andreas M

    2015-11-01

    Diffusion of colloidal particles in a complex environment such as polymer networks or biological cells is a topic of high complexity with significant biological and medical relevance. In such situations, the interaction between the surroundings and the particle motion has to be taken into account. We analyze a simplified diffusion model that includes some aspects of a complex environment in the framework of a nonlinear friction process: at low particle speeds, friction grows linearly with the particle velocity as for regular viscous friction; it grows more than linearly at higher particle speeds; finally, at a maximum of the possible particle speed, the friction diverges. In addition to bare diffusion, we study the influence of a constant drift force acting on the diffusing particle. While the corresponding stationary velocity distributions can be derived analytically, the displacement statistics generally must be determined numerically. However, as a benefit of our model, analytical progress can be made in one case of a special maximum particle speed. The effect of a drift force in this case is analytically determined by perturbation theory. It will be interesting in the future to compare our results to real experimental systems. One realization could be magnetic colloidal particles diffusing through a shear-thickening environment such as starch suspensions, possibly exposed to an external magnetic field gradient. PMID:26651690

  7. Asymmetric generalization in adaptation to target displacement errors in humans and in a neural network model.

    PubMed

    Westendorff, Stephanie; Kuang, Shenbing; Taghizadeh, Bahareh; Donchin, Opher; Gail, Alexander

    2015-04-01

    Different error signals can induce sensorimotor adaptation during visually guided reaching, possibly evoking different neural adaptation mechanisms. Here we investigate reach adaptation induced by visual target errors without perturbing the actual or sensed hand position. We analyzed the spatial generalization of adaptation to target error to compare it with other known generalization patterns and simulated our results with a neural network model trained to minimize target error independent of prediction errors. Subjects reached to different peripheral visual targets and had to adapt to a sudden fixed-amplitude displacement ("jump") consistently occurring for only one of the reach targets. Subjects simultaneously had to perform contralateral unperturbed saccades, which rendered the reach target jump unnoticeable. As a result, subjects adapted by gradually decreasing reach errors and showed negative aftereffects for the perturbed reach target. Reach errors generalized to unperturbed targets according to a translational rather than rotational generalization pattern, but locally, not globally. More importantly, reach errors generalized asymmetrically with a skewed generalization function in the direction of the target jump. Our neural network model reproduced the skewed generalization after adaptation to target jump without having been explicitly trained to produce a specific generalization pattern. Our combined psychophysical and simulation results suggest that target jump adaptation in reaching can be explained by gradual updating of spatial motor goal representations in sensorimotor association networks, independent of learning induced by a prediction-error about the hand position. The simulations make testable predictions about the underlying changes in the tuning of sensorimotor neurons during target jump adaptation. PMID:25609106

  8. Adjoint Assimilation of ARGO float displacement data into an eddy-resolving ocean model

    NASA Astrophysics Data System (ADS)

    Filatoff, N.; Assenbaum, M.

    2003-04-01

    Within the SHOM/BRESM assimilation group in Toulouse, France, we are investigating means of assimilating ARGO float displacement data into a regional open-boundary implementation of MICOM. The model area covers a small part of the North Atlantic Ocean off the portugese coast, where intensive surveys and float releases were performed in years 2000 and 2001 within the french POMME experiment. Our special topic of interest is the behaviour of assimilation methods with respect to mesoscale structures such as eddies and fronts. The ARGO float cycle of typically 10 days introduces weak or strong aliasing of these structures. The methods beeing developed and tested include various implementation of objective analysis as well as variational methods. Our approach is pragmatic : the methods are implemented and their performances for analysis and forecast are compared, using observed float data provided by the CORIOLIS real-time data center in Brest. We will expose our model and assimilation setup and show results using sequential and variational methods.

  9. Dynamic modeling of mass-flowing linear medium with large amplitude displacement and rotation

    NASA Astrophysics Data System (ADS)

    Hong, Difeng; Tang, Jiali; Ren, Gexue

    2011-11-01

    In this paper, a dynamic model of a linear medium with mass flow, such as traveling strings, cables, belts, beams or pipes conveying fluids, is proposed, in the framework of Arbitrary-Lagrange-Euler (ALE) description. The material coordinate is introduced to characterize the mass-flow of the medium, and the Absolute Nodal Coordinate Formulation (ANCF) is employed to capture geometric nonlinearity of the linear media under large displacement and rotation. The governing equations are derived in terms of d'Alembert's principle. When using an ALE description, complex mass-flowing boundary conditions can be easily enforced. Numerical examples are presented to validate the proposed method by comparison with analytical results of simplified models. The computed critical fluid velocity for the stability of a cantilevered pipe conveying fluid is correlated with the available theory in literature. The large amplitude limit-cycle oscillations of flexible pipes conveying fluid are presented, and the effect of the velocity of the fluid on the static equilibrium of the pipe under gravity is investigated.

  10. Velocity and displacement statistics in a stochastic model of nonlinear friction showing bounded particle speed

    NASA Astrophysics Data System (ADS)

    Menzel, Andreas M.

    2015-11-01

    Diffusion of colloidal particles in a complex environment such as polymer networks or biological cells is a topic of high complexity with significant biological and medical relevance. In such situations, the interaction between the surroundings and the particle motion has to be taken into account. We analyze a simplified diffusion model that includes some aspects of a complex environment in the framework of a nonlinear friction process: at low particle speeds, friction grows linearly with the particle velocity as for regular viscous friction; it grows more than linearly at higher particle speeds; finally, at a maximum of the possible particle speed, the friction diverges. In addition to bare diffusion, we study the influence of a constant drift force acting on the diffusing particle. While the corresponding stationary velocity distributions can be derived analytically, the displacement statistics generally must be determined numerically. However, as a benefit of our model, analytical progress can be made in one case of a special maximum particle speed. The effect of a drift force in this case is analytically determined by perturbation theory. It will be interesting in the future to compare our results to real experimental systems. One realization could be magnetic colloidal particles diffusing through a shear-thickening environment such as starch suspensions, possibly exposed to an external magnetic field gradient.

  11. Population-Dynamic Modeling of Bacterial Horizontal Gene Transfer by Natural Transformation.

    PubMed

    Mao, Junwen; Lu, Ting

    2016-01-01

    Natural transformation is a major mechanism of horizontal gene transfer (HGT) and plays an essential role in bacterial adaptation, evolution, and speciation. Although its molecular underpinnings have been increasingly revealed, natural transformation is not well characterized in terms of its quantitative ecological roles. Here, by using Neisseria gonorrhoeae as an example, we developed a population-dynamic model for natural transformation and analyzed its dynamic characteristics with nonlinear tools and simulations. Our study showed that bacteria capable of natural transformation can display distinct population behaviors ranging from extinction to coexistence and to bistability, depending on their HGT rate and selection coefficient. With the model, we also illustrated the roles of environmental DNA sources-active secretion and passive release-in impacting population dynamics. Additionally, by constructing and utilizing a stochastic version of the model, we examined how noise shapes the steady and dynamic behaviors of the system. Notably, we found that distinct waiting time statistics for HGT events, namely a power-law distribution, an exponential distribution, and a mix of the both, are associated with the dynamics in the regimes of extinction, coexistence, and bistability accordingly. This work offers a quantitative illustration of natural transformation by revealing its complex population dynamics and associated characteristics, therefore advancing our ecological understanding of natural transformation as well as HGT in general. PMID:26745428

  12. Modeling vertical and horizontal solute transport for the Weldon Spring Site Remedial Action Project

    SciTech Connect

    Tomasko, D.

    1992-11-01

    This technical memorandum presents a one-dimensional model to simulate the transport of a contaminant that originates as a liquid release, moves vertically downward through a vadose zone, mixes with initially clean groundwater in an unconfined aquifer, and ends at a downgradient extraction well. Vertical and horizontal segments of the contaminant pathway are coupled by assuming that the breakthrough curve of the contaminant at the water table acts as a contaminant source for the unconfined aquifer. For simplicity, this source is assumed to be a time-shifted unit square wave having an amplitude equal to the peak breakthrough concentration at the water table and a duration equal to the full width of the breakthrough curve at the half-maximum concentration value. The effects of dilution at the water-table interface are evaluated with a simple mass-balance equation. Comparing the model results for the chemical plant area of the Weldon Spring site near St. Louis, Missouri, and the Envirocare facility located near Salt Lake City, Utah, with those obtained from a solution formulated with the real and imaginary parts of a Fourier series in Laplace space indicates that the model provides a conservative estimate of the contaminant breakthrough curve at the receptor.

  13. Assessing the sensitivity to horizontal resolution of Unified Model simulations of Hurricane Katrina

    NASA Astrophysics Data System (ADS)

    O'Hara, J. P.; Webster, S.

    2012-12-01

    In August 2005 Hurricane Katrina made landfall close to New Orleans with devastating consequences. It was one of the strongest storms to impact the coast of the United States and was also one of the most costly. At peak intensity, its central pressure was 902 hPa and 10 m wind speeds were 175 mph. The extreme nature of this weather system therefore makes it an ideal case study to assess the ability of the Met Office Unified Model to simulate and potentially forecast such phenomena. In this study we assess the ability of the Met Office Unified Model (UM) to simulate Hurricane Katrina at a range of horizontal resolutions. Thus a set of limited area model simulations have been performed at resolutions of 1.5 km, 4 km and 24 km. By careful implementation of the lateral boundary conditions it has been possible to (one way) nest all these simulations inside the 25 km operational global forecast model version of the UM. The configuration of the 1.5 km and 4 km models is based on the 1.5 km and 4 km models used operationally over the UK and hence convection is treated explicitly, whilst the 24 km LAM is configured in the same way as the operational global forecast model and hence convection is parametrized. The simulations are all performed on a 2400 km x 1600 km domain and are all initialised around four days prior to landfall, when the observed central pressure was close to 990 hPa. The initial data for the simulations are ERA-interim analyses with the 25 km global forecast generating hourly LBCs via a series of 24 hour long forecasts initialised from successive 12z analyses. Overall, these simulations have been configured in order to make as clean an assessment as possible of the impact of horizontal resolution on the simulation of Hurricane Katrina. In this presentation we first describe and illustrate results summarising the impact of model resolution on the simulated hurricane. Consistent with the systematic tropical cyclone behaviour of the global forecast model

  14. Investigation into a displacement bias in numerical weather prediction models' forecasts of mesoscale convective systems

    NASA Astrophysics Data System (ADS)

    Yost, Charles

    Although often hard to correctly forecast, mesoscale convective systems (MCSs) are responsible for a majority of warm-season, localized extreme rain events. This study investigates displacement errors often observed by forecasters and researchers in the Global Forecast System (GFS) and the North American Mesoscale (NAM) models, in addition to the European Centre for Medium Range Weather Forecasts (ECMWF) and the 4-km convection allowing NSSL-WRF models. Using archived radar data and Stage IV precipitation data from April to August of 2009 to 2011, MCSs were recorded and sorted into unique six-hour intervals. The locations of these MCSs were compared to the associated predicted precipitation field in all models using the Method for Object-Based Diagnostic Evaluation (MODE) tool, produced by the Developmental Testbed Center and verified through manual analysis. A northward bias exists in the location of the forecasts in all lead times of the GFS, NAM, and ECMWF models. The MODE tool found that 74%, 68%, and 65% of the forecasts were too far to the north of the observed rainfall in the GFS, NAM and ECMWF models respectively. The higher-resolution NSSL-WRF model produced a near neutral location forecast error with 52% of the cases too far to the south. The GFS model consistently moved the MCSs too quickly with 65% of the cases located to the east of the observed MCS. The mean forecast displacement error from the GFS and NAM were on average 266 km and 249 km, respectively, while the ECMWF and NSSL-WRF produced a much lower average of 179 km and 158 km. A case study of the Dubuque, IA MCS on 28 July 2011 was analyzed to identify the root cause of this bias. This MCS shattered several rainfall records and required over 50 people to be rescued from mobile home parks from around the area. This devastating MCS, which was a classic Training Line/Adjoining Stratiform archetype, had numerous northward-biased forecasts from all models, which are examined here. As common with

  15. Updated Rupture Model for the M7.8 October 28, 2012, Haida Gwaii Earthquake as Constrained by GPS-Observed Displacements

    NASA Astrophysics Data System (ADS)

    Nykolaishen, L.; Dragert, H.; Wang, K.; James, T. S.; de Lange Boom, B.; Schmidt, M.; Sinnott, D.

    2014-12-01

    The M7.8 low-angle thrust earthquake off the west coast of southern Haida Gwaii on October 28, 2012, provided Canadian scientists the opportunity to study a local large thrust earthquake and has provided important information towards an improved understanding of geohazards in coastal British Columbia. Most large events along the Pacific-North America boundary in this region have involved strike-slip motion, such as the 1949 M8.1 earthquake on the Queen Charlotte Fault. In contrast along the southern portion of Haida Gwaii, the young (~8 Ma) Pacific plate crust also underthrusts North America and has been viewed as a small-scale analogy of the Cascadia Subduction Zone. Initial seismic-based rupture models for this event were improved through inclusion of GPS observed coseismic displacements, which are as large as 115 cm of horizontal motion (SSW) and 30 cm of subsidence. Additional campaign-style GPS surveys have since been repeated by the Canadian Hydrographic Service (CHS) at seven vertical reference benchmarks throughout Haida Gwaii, significantly improving the coverage of coseismic displacement observations in the region. These added offsets were typically calculated by differencing a single occupation before and after the earthquake and preliminary displacement estimates are consistent with previous GPS observations from the Geological Survey of Canada. Addition of the CHS coseismic offset estimates may allow direct inversion of the GPS data to derive a purely GPS-based rupture model. To date, cumulative postseismic displacements at six sites indicate up to 6 cm of motion, varying in azimuth between SSW and SE. Preliminary postseismic timeseries curve fitting to date has utilized a double exponential function characteristic of mantle relaxation. The current postseismic trends also suggest afterslip on the deeper plate interface beneath central Haida Gwaii along with possible induced aseismic slip on a deeper segment of the Queen Charlotte Fault located offshore

  16. The distance scale to globular clusters through new horizontal branch models.

    NASA Astrophysics Data System (ADS)

    Caloi, V.; D'Antona, F.; Mazzitelli, I.

    1997-04-01

    As a completion of preceding work (Mazzitelli et al. 1995A&A...302..382M), we present new horizontal branch models with mass fractions of heavy element content Z=2x10^-4^ and 6x10^-4^; we discuss the complete set of models with Z from 10^-4^ to 3x10^-3^, and their implications for the ages of galactic globular clusters. Models at low Z are ~0.15mag more luminous than equivalent models of the previous generation, implying a reduction of globular cluster ages of ~2Gyr. Half of this effect depends on the core masses at the helium flash, which are larger by 0.007Msun_ at Z=10^-4^; the remaining half depends on the new microphysical inputs (equation of state and opacities) in present models. The distance scale resulting from these new models for [Fe/H]<~-1 is consistent with Sandage (1993) and Walker (1992) scales, but not with Carney et al. (1992) scale. The relation M_v_(ZAHB) vs. [Fe/H] is not linear, so that the notion of slope turns out to be an elusive one, and in any case depending on the range of [Fe/H] considered. New computations of the core mass at the helium flash are presented and discussed. We finally show that the luminosity at the tip of the giant branch obtained in our computations is compatible with the maximum luminosity of giants observed in globular clusters by Frogel et al. (1983).

  17. Postglacial species displacement in Triturus newts deduced from asymmetrically introgressed mitochondrial DNA and ecological niche models

    PubMed Central

    2012-01-01

    Background If the geographical displacement of one species by another is accompanied by hybridization, mitochondrial DNA can introgress asymmetrically, from the outcompeted species into the invading species, over a large area. We explore this phenomenon using the two parapatric crested newt species, Triturus macedonicus and T. karelinii, distributed on the Balkan Peninsula in south-eastern Europe, as a model. Results We first delimit a ca. 54,000 km2 area in which T. macedonicus contains T. karelinii mitochondrial DNA. This introgression zone bisects the range of T. karelinii, cutting off a T. karelinii enclave. The high similarity of introgressed mitochondrial DNA haplotypes with those found in T. karelinii suggests a recent transfer across the species boundary. We then use ecological niche modeling to explore habitat suitability of the location of the present day introgression zone under current, mid-Holocene and Last Glacial Maximum conditions. This area was inhospitable during the Last Glacial Maximum for both species, but would have been habitable at the mid-Holocene. Since the mid-Holocene, habitat suitability generally increased for T. macedonicus, whereas it decreased for T. karelinii. Conclusion The presence of a T. karelinii enclave suggests that T. karelinii was the first to colonize the area where the present day introgression zone is positioned after the Last Glacial Maximum. Subsequently, we propose T. karelinii was outcompeted by T. macedonicus, which captured T. karelinii mitochondrial DNA via introgressive hybridization in the process. Ecological niche modeling suggests that this replacement was likely facilitated by a shift in climate since the mid-Holocene. We suggest that the northwestern part of the current introgression zone was probably never inhabited by T. karelinii itself, and that T. karelinii mitochondrial DNA spread there through T. macedonicus exclusively. Considering the spatial distribution of the introgressed mitochondrial DNA and

  18. Tools and Algorithms to Link Horizontal Hydrologic and Vertical Hydrodynamic Models and Provide a Stochastic Modeling Framework

    NASA Astrophysics Data System (ADS)

    Salah, Ahmad M.; Nelson, E. James; Williams, Gustavious P.

    2010-04-01

    We present algorithms and tools we developed to automatically link an overland flow model to a hydrodynamic water quality model with different spatial and temporal discretizations. These tools run the linked models which provide a stochastic simulation frame. We also briefly present the tools and algorithms we developed to facilitate and analyze stochastic simulations of the linked models. We demonstrate the algorithms by linking the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model for overland flow with the CE-QUAL-W2 model for water quality and reservoir hydrodynamics. GSSHA uses a two-dimensional horizontal grid while CE-QUAL-W2 uses a two-dimensional vertical grid. We implemented the algorithms and tools in the Watershed Modeling System (WMS) which allows modelers to easily create and use models. The algorithms are general and could be used for other models. Our tools create and analyze stochastic simulations to help understand uncertainty in the model application. While a number of examples of linked models exist, the ability to perform automatic, unassisted linking is a step forward and provides the framework to easily implement stochastic modeling studies.

  19. Sub-grid drag models for horizontal cylinder arrays immersed in gas-particle multiphase flows

    SciTech Connect

    Sarkar, Avik; Sun, Xin; Sundaresan, Sankaran

    2013-09-08

    Immersed cylindrical tube arrays often are used as heat exchangers in gas-particle fluidized beds. In multiphase computational fluid dynamics (CFD) simulations of large fluidized beds, explicit resolution of small cylinders is computationally infeasible. Instead, the cylinder array may be viewed as an effective porous medium in coarse-grid simulations. The cylinders' influence on the suspension as a whole, manifested as an effective drag force, and on the relative motion between gas and particles, manifested as a correction to the gas-particle drag, must be modeled via suitable sub-grid constitutive relationships. In this work, highly resolved unit-cell simulations of flow around an array of horizontal cylinders, arranged in a staggered configuration, are filtered to construct sub-grid, or `filtered', drag models, which can be implemented in coarse-grid simulations. The force on the suspension exerted by the cylinders is comprised of, as expected, a buoyancy contribution, and a kinetic component analogous to fluid drag on a single cylinder. Furthermore, the introduction of tubes also is found to enhance segregation at the scale of the cylinder size, which, in turn, leads to a reduction in the filtered gas-particle drag.

  20. Modeling and analysis of ORNL horizontal storage tank mobilization and mixing

    SciTech Connect

    Mahoney, L.A.; Terrones, G.; Eyler, L.L.

    1994-06-01

    The retrieval and treatment of radioactive sludges that are stored in tanks constitute a prevalent problem at several US Department of Energy sites. The tanks typically contain a settled sludge layer with non-Newtonian rheological characteristics covered by a layer of supernatant. The first step in retrieval is the mobilization and mixing of the supernatant and sludge in the storage tanks. Submerged jets have been proposed to achieve sludge mobilization in tanks, including the 189 m{sup 3} (50,000 gallon) Melton Valley Storage tanks (MVST) at Oak Ridge National Laboratory (ORNL) and the planned 378 m{sup 3} (100,000 gallon) tanks being designed as part of the MVST Capacity Increase Project (MVST-CIP). This report focuses on the modeling of mixing and mobilization in horizontal cylindrical tanks like those of the MVST design using submerged, recirculating liquid jets. The computer modeling of the mobilization and mixing processes uses the TEMPEST computational fluid dynamics program (Trend and Eyler 1992). The goals of the simulations are to determine under what conditions sludge mobilization using submerged liquid jets is feasible in tanks of this configuration, and to estimate mixing times required to approach homogeneity of the contents.

  1. Modeling of stress-triggered faulting and displacement magnitude along Agenor Linea, Europa

    NASA Astrophysics Data System (ADS)

    Nahm, A.; Cameron, M. E.; Smith-Konter, B. R.; Pappalardo, R. T.

    2012-12-01

    We investigate the relationship between shear and normal stresses at Agenor Linea (AL) to better understand the role of tidal stress sources and implications for faulting on Europa. AL is a ~1500 km long, E-W trending, 20-30 km wide zone of geologically young deformation located in the southern hemisphere, and it forks into two branches at its eastern end. Based on photogeological evidence and stress orientation predictions, AL is primarily a right-lateral strike slip fault and may have accommodated up to 20 km of right-lateral slip. We compute tidal shear and normal stresses along present-day AL using SatStress, a numerical code that calculates tidal stresses at any point on the surface of a satellite for both diurnal and non-synchronous rotation (NSR) stresses. We adopt model parameters appropriate for Europa with a spherically symmetric, 20 km thick ice shell underlain by a global subsurface ocean and assume a coefficient of friction μ = 0.6. Along AL, shear stresses are primarily right-lateral (~1.8 MPa), while normal stresses are predominantly compressive along the west side of the structure (~0.7 MPa) and tensile along the east side (~2.9 MPa). Failure along AL is assessed using the Coulomb failure criterion, which states that shear failure occurs when the shear stress exceeds the frictional resistance of the fault. Where fault segments meet these conditions for shear failure, coseismic displacements are determined (assuming complete stress drop). We calculate shallow displacements as large as ~50 m at 1 km depth and ~10 m at 3 km depth. Triggered stresses from coseismic fault slip may also contribute to the total slip. We investigate the role of stress triggering by computing the change in Coulomb failure stress (ΔCFS) along AL. Where slip has occurred, negative ΔCFS is calculated; positive ΔCFS values indicate segments where failure is promoted. Positive ΔCFS is calculated at the western tip and the intersection of the branches with the main fault at a

  2. Back Analysis of Rock Mass Displacements Around a Deep Shaft Using Two- and Three-Dimensional Continuum Modeling

    NASA Astrophysics Data System (ADS)

    Rafiei Renani, Hossein; Martin, C. Derek; Hudson, Richard

    2016-04-01

    An instrumented section of a 10-m-diameter circular shaft located at a depth of 1.2 km in an average quality rock mass was back analyzed to establish the rock mass behavior. Extensometers were installed radially at four locations and provided the primary data for the back analyses. Three- and two-dimensional continuum models were analyzed using the numerical codes FLAC3Dand Phase2 to assess the rock mass behavior. An initial set of mechanical parameters obtained from empirical relationships were found to give a reasonable match to the measured response of extensometers 2 and 4, when using a Mohr-Coulomb strain softening model. A different set of parameters were needed for FLAC3D when trying to match the significantly higher displacements recorded by only one of the extensometer. It was noted that regardless of the material model and corresponding parameters, the three-dimensional models were not able to give reasonable match to the results of all extensometers. It was shown that for the given problem, there is a theoretical limit for ratio of displacements predicted for different extensometers using a continuum isotropic material model. The two-dimensional models in Phase2, however, gave an apparently better overall match to all the extensometers. Comparison of the results of three-dimensional models with the assumed longitudinal displacement profile for the two-dimensional model indicated that the three-dimensional effects were not adequately captured in the two-dimensional model.

  3. The effect of increased horizontal resolution on synoptic forecasts with the GISS model of the global atmosphere

    NASA Technical Reports Server (NTRS)

    Quirk, W. J.; Atlas, R. M.

    1977-01-01

    The improved horizontal resolution global circulation model in question has a horizontal spacing of 2.5 deg latitude by 3 deg longitude for a resolution of about 250 km in midlatitude. This paper reports on experiments to determine the improvements in forecasting skill and in initial conditions that were made possible by the ultrafine resolution and ultrafine assimilation. The size of the improvement in skill score when the ultrafine model is used for forecasting and assimilation was so large that 60-hour forecasts with the ultrafine model had as good a skill score as the 48-hour forecasts with the fine model. Synoptic evaluations confirmed that ultrafine model forecasts are better than the fine model forecasts.

  4. New modelling of transient well test and rate decline analysis for a horizontal well in a multiple-zone reservoir

    NASA Astrophysics Data System (ADS)

    Nie, Ren-Shi; Guo, Jian-Chun; Jia, Yong-Lu; Zhu, Shui-Qiao; Rao, Zheng; Zhang, Chun-Guang

    2011-09-01

    The no-type curve with negative skin of a horizontal well has been found in the current research. Negative skin is very significant to transient well test and rate decline analysis. This paper first presents the negative skin problem where the type curves with negative skin of a horizontal well are oscillatory. In order to solve the problem, we propose a new model of transient well test and rate decline analysis for a horizontal well in a multiple-zone composite reservoir. A new dimensionless definition of rD is introduced in the dimensionless mathematical modelling under different boundaries. The model is solved using the Laplace transform and separation of variables techniques. In Laplace space, the solutions for both constant rate production and constant wellbore pressure production are expressed in a unified formula. We provide graphs and thorough analysis of the new standard type curves for both well test and rate decline analysis; the characteristics of type curves are the reflections of horizontal well production in a multiple-zone reservoir. An important contribution of our paper is that our model removed the oscillation in type curves and thus solved the negative skin problem. We also show that the characteristics of type curves depend heavily on the properties of different zones, skin factor, well length, formation thickness, etc. Our research can be applied to a real case study.

  5. Modeling and experiment of the suspended seismometer concept for attenuating the contribution of tilt motion in horizontal measurements

    NASA Astrophysics Data System (ADS)

    Matichard, F.; Evans, M.; Mittleman, R.; MacInnis, M.; Biscans, S.; Dooley, K. L.; Sohier, H.; Lauriero, A.; Paris, H.; Koch, J.; Knothe, P.; Carbajo, A.; Dufort, C.

    2016-06-01

    Tilt-horizontal coupling in inertial sensors limits the performance of active isolation systems such as those used in gravitational wave detectors. Inertial rotation sensors can be used to subtract the tilt component from the signal produced by horizontal inertial sensors, but such techniques are often limited by the sensor noise of the tilt measurement. A different approach is to mechanically filter the tilt transmitted to the horizontal inertial sensor, as discussed in this article. This technique does not require an auxiliary rotation sensor and can produce a lower noise measurement. The concept investigated uses a mechanical suspension to isolate the inertial sensor from input tilt. Modeling and simulations show that such a configuration can be used to adequately attenuate the tilt transmitted to the instrument, while maintaining translation sensitivity in the frequency band of interest. The analysis is supported by experimental results showing that this approach is a viable solution to overcome the tilt problem in the field of active inertial isolation.

  6. Asymmetric generalization in adaptation to target displacement errors in humans and in a neural network model

    PubMed Central

    Westendorff, Stephanie; Kuang, Shenbing; Taghizadeh, Bahareh; Donchin, Opher

    2015-01-01

    Different error signals can induce sensorimotor adaptation during visually guided reaching, possibly evoking different neural adaptation mechanisms. Here we investigate reach adaptation induced by visual target errors without perturbing the actual or sensed hand position. We analyzed the spatial generalization of adaptation to target error to compare it with other known generalization patterns and simulated our results with a neural network model trained to minimize target error independent of prediction errors. Subjects reached to different peripheral visual targets and had to adapt to a sudden fixed-amplitude displacement (“jump”) consistently occurring for only one of the reach targets. Subjects simultaneously had to perform contralateral unperturbed saccades, which rendered the reach target jump unnoticeable. As a result, subjects adapted by gradually decreasing reach errors and showed negative aftereffects for the perturbed reach target. Reach errors generalized to unperturbed targets according to a translational rather than rotational generalization pattern, but locally, not globally. More importantly, reach errors generalized asymmetrically with a skewed generalization function in the direction of the target jump. Our neural network model reproduced the skewed generalization after adaptation to target jump without having been explicitly trained to produce a specific generalization pattern. Our combined psychophysical and simulation results suggest that target jump adaptation in reaching can be explained by gradual updating of spatial motor goal representations in sensorimotor association networks, independent of learning induced by a prediction-error about the hand position. The simulations make testable predictions about the underlying changes in the tuning of sensorimotor neurons during target jump adaptation. PMID:25609106

  7. Performance and Economic Modeling of Horizontally Drilled Ground-Source Heat Pumps in Select California Climates

    NASA Astrophysics Data System (ADS)

    Wiryadinata, Steven

    Service life modeling was performed to gage the viability of unitary 3.5 kWt, ground-source terminal heat pumps (GTHP) employing horizontal directionally drilled geothermal heat exchangers (GHX) over air-source terminal heat pumps (PTHP) in hotels and motels and residential apartment building sectors in California's coastal and inland climates. Results suggest the GTHP can reduce hourly peak demand for the utility by 7%-25% compared to PTHP, depending on the climate and building type. The annual energy savings, which range from -1% to 5%, are highly dependent on the GTHP pump energy use relative to the energy savings attributed to the difference in ground and air temperatures (DeltaT). In mild climates with small ?T, the pump energy use may overcome any advantage to utilizing a GHX. The majority of total levelized cost savings - ranging from 0.18/ft2 to 0.3/ft 2 - are due to reduced maintenance and lifetime capital cost normally associated with geothermal heat pump systems. Without these reductions (not validated for the GTHP system studied), the GTHP technology does not appear to offer significant advantages over PTHP in the climate zones studied here. The GTHP levelized cost was most sensitive to variations in installed cost and in some cases, energy use (influenced by climate zone choice), which together highlights the importance of climate selection for installation, and the need for larger market penetration of ground-source systems in order to bring down installed costs as the technology matures.

  8. Modelling Air and Water Two-Phase Annular Flow in a Small Horizontal Pipe

    NASA Astrophysics Data System (ADS)

    Yao, Jun; Yao, Yufeng; Arini, Antonino; McIiwain, Stuart; Gordon, Timothy

    2016-06-01

    Numerical simulation using computational fluid dynamics (CFD) has been carried out to study air and water two-phase flow in a small horizontal pipe of an inner diameter of 8.8mm, in order to investigate unsteady flow pattern transition behaviours and underlying physical mechanisms. The surface liquid film thickness distributions, determined by either wavy or full annular flow regime, are shown in reasonable good agreement with available experimental data. It was demonstrated that CFD simulation was able to predict wavy flow structures accurately using two-phase flow sub-models embedded in ANSYS-Fluent solver of Eulerian-Eulerian framework, together with a user defined function subroutine ANWAVER-UDF. The flow transient behaviours from bubbly to annular flow patterns and the liquid film distributions revealed the presence of gas/liquid interferences between air and water film interface. An increase of upper wall liquid film thickness along the pipe was observed for both wavy annular and full annular scenarios. It was found that the liquid wavy front can be further broken down to form the water moisture with liquid droplets penetrating upwards. There are discrepancies between CFD predictions and experimental data on the liquid film thickness determined at the bottom and the upper wall surfaces, and the obtained modelling information can be used to assist further 3D user defined function subroutine development, especially when CFD simulation becomes much more expense to model full 3D two-phase flow transient performance from a wavy annular to a fully developed annular type.

  9. Evaluation of global horizontal irradiance to plane-of-array irradiance models at locations across the United States

    DOE PAGESBeta

    Lave, Matthew; Hayes, William; Pohl, Andrew; Hansen, Clifford W.

    2015-02-02

    We report an evaluation of the accuracy of combinations of models that estimate plane-of-array (POA) irradiance from measured global horizontal irradiance (GHI). This estimation involves two steps: 1) decomposition of GHI into direct and diffuse horizontal components and 2) transposition of direct and diffuse horizontal irradiance (DHI) to POA irradiance. Measured GHI and coincident measured POA irradiance from a variety of climates within the United States were used to evaluate combinations of decomposition and transposition models. A few locations also had DHI measurements, allowing for decoupled analysis of either the decomposition or the transposition models alone. Results suggest that decompositionmore » models had mean bias differences (modeled versus measured) that vary with climate. Transposition model mean bias differences depended more on the model than the location. Lastly, when only GHI measurements were available and combinations of decomposition and transposition models were considered, the smallest mean bias differences were typically found for combinations which included the Hay/Davies transposition model.« less

  10. Horizontal and vertical velocities derived from the IDS contribution to ITRF2014, and comparisons with geophysical models

    NASA Astrophysics Data System (ADS)

    Moreaux, G.; Lemoine, F. G.; Argus, D. F.; Santamaría-Gómez, A.; Willis, P.; Soudarin, L.; Gravelle, M.; Ferrage, P.

    2016-07-01

    In the context of the 2014 realization of the International Terrestrial Reference Frame (ITRF2014), the International DORIS Service (IDS) has delivered to the IERS a set of 1140 weekly SINEX files including station coordinates and Earth orientation parameters, covering the time period from 1993.0 to 2015.0. From this set of weekly SINEX files, the IDS Combination Center estimated a cumulative DORIS position and velocity solution to obtain mean horizontal and vertical motion of 160 stations at 71 DORIS sites. The main objective of this study is to validate the velocities of the DORIS sites by comparison with external models or time series. Horizontal velocities are compared with two recent global plate models (GEODVEL 2010 and NNR-MORVEL56). Prior to the comparisons, DORIS horizontal velocities were corrected for Global Isostatic Adjustment (GIA) from the ICE-6G (VM5a) model. For more than half of the sites, the DORIS horizontal velocities differ from the global plate models by less than 2-3 mm/yr. For five of the sites (Arequipa, Dionysos/Gavdos, Manila, Santiago) with horizontal velocity differences wrt these models larger than 10 mm/yr, comparisons with GNSS estimates show the veracity of the DORIS motions. Vertical motions from the DORIS cumulative solution are compared with the vertical velocities derived from the latest GPS cumulative solution over the time span 1995.0-2014.0 from the University of La Rochelle (ULR6) solution at 31 co-located DORIS-GPS sites. These two sets of vertical velocities show a correlation coefficient of 0.83. Vertical differences are larger than 2 mm/yr at 23 percent of the sites. At Thule the disagreement is explained by fine-tuned DORIS discontinuities in line with the mass variations of outlet glaciers. Furthermore, the time evolution of the vertical time series from the DORIS station in Thule show similar trends to the GRACE equivalent water height.

  11. Experimental study of stable imbibition displacements in a model open fracture. I. Local avalanche dynamics.

    PubMed

    Clotet, Xavier; Ortín, Jordi; Santucci, Stéphane

    2016-01-01

    We report the results of an experimental investigation of the spatiotemporal dynamics of stable imbibition fronts in a disordered medium, in the regime of capillary disorder, for a wide range of experimental conditions. We have used silicone oils of various viscosities μ and nearly identical oil-air surface tension and forced them to slowly invade a model open fracture at different constant flow rates v. In this first part of the study we have focused on the local dynamics at a scale below the size of the quenched disorder. Changing μ and v independently, we have found that the dynamics is not simply controlled by the capillary number Ca∼μv. Specifically, we have found that the wide statistical distributions of local front velocities, and their large spatial correlations along the front, are indeed controlled by the capillary number Ca. However, local velocities exhibit also very large temporal correlations, and these correlations depend more strongly on the mean imposed velocity v than on the viscosity μ of the invading fluid. Correlations between local velocities lead to a burstlike dynamics. Avalanches, defined as clusters of large local velocities, follow power-law distributions-both in size and duration-with exponential cutoffs that diverge as Ca→0, the pinning-depinning transition of stable imbibition displacements. Large data sets have led to reliable statistics, from which we have derived accurate values of critical exponents of the relevant power-law distributions. We have investigated also the dependence of their cutoffs on μ and v and related them to the autocorrelations of local velocities in space and time. PMID:26871064

  12. Displacement cascades in Fesbnd Nisbnd Mnsbnd Cu alloys: RVP model alloys

    NASA Astrophysics Data System (ADS)

    Terentyev, D.; Zinovev, A.; Bonny, G.

    2016-07-01

    Primary damage due to displacement cascades (10-100 keV) has been assessed in Fesbnd 1%Mnsbnd 1%Ni-0.5%Cu and its binary alloys by molecular dynamics (MD), using a recent interatomic potential, specially developed to address features of the Fesbnd Mnsbnd Nisbnd Cu system in the dilute limit. The latter system represents the model matrix for reactor pressure vessel steels. The applied potential reproduces major interaction features of the solutes with point defects in the binary, ternary and quaternary dilute alloys. As compared to pure Fe, the addition of one type of a solute or all solutes together does not change the major characteristics of primary damage. However, the chemical structure of the self-interstitial defects is strongly sensitive to the presence and distribution of Mn and Cu in the matrix. 20 keV cascades were also studied in the Fesbnd Nisbnd Mnsbnd Cu matrix containing <100> dislocation loops (with density of 1024 m-3 and size 2 nm). Two solute distributions were investigated, namely: a random one and one obtained by Metropolis Monte Carlo simulations from our previous work. The presence of the loops did not affect the defect production efficiency but slightly reduced the fraction of isolated self-interstitials and vacancies. The cascade event led to the transformation of the loops into ½<111> glissile configurations with a success rate of 10% in the matrix with random solute distribution, while all the pre-created loops remain stable if the alloy's distribution was applied using the Monte-Carlo method. This suggests that solute segregation to loops "stabilizes" the pre-existing loops against transformation or migration induced by collision cascades.

  13. Experimental study of stable imbibition displacements in a model open fracture. I. Local avalanche dynamics

    NASA Astrophysics Data System (ADS)

    Clotet, Xavier; Ortín, Jordi; Santucci, Stéphane

    2016-01-01

    We report the results of an experimental investigation of the spatiotemporal dynamics of stable imbibition fronts in a disordered medium, in the regime of capillary disorder, for a wide range of experimental conditions. We have used silicone oils of various viscosities μ and nearly identical oil-air surface tension and forced them to slowly invade a model open fracture at different constant flow rates v . In this first part of the study we have focused on the local dynamics at a scale below the size of the quenched disorder. Changing μ and v independently, we have found that the dynamics is not simply controlled by the capillary number Ca˜μ v . Specifically, we have found that the wide statistical distributions of local front velocities, and their large spatial correlations along the front, are indeed controlled by the capillary number Ca. However, local velocities exhibit also very large temporal correlations, and these correlations depend more strongly on the mean imposed velocity v than on the viscosity μ of the invading fluid. Correlations between local velocities lead to a burstlike dynamics. Avalanches, defined as clusters of large local velocities, follow power-law distributions—both in size and duration—with exponential cutoffs that diverge as Ca→0 , the pinning-depinning transition of stable imbibition displacements. Large data sets have led to reliable statistics, from which we have derived accurate values of critical exponents of the relevant power-law distributions. We have investigated also the dependence of their cutoffs on μ and v and related them to the autocorrelations of local velocities in space and time.

  14. Pore-scale simulation of liquid CO2 displacement of water using a two-phase lattice Boltzmann model

    SciTech Connect

    Liu, Haihu; Valocchi, Albert J.; Werth, Charles J.; Kang, Oinjun; Oostrom, Martinus

    2014-11-01

    A lattice Boltzmann color-fluid model, which was recently proposed by Liu et al. [H. Liu, A.J. Valocchi, and Q. Kang. Three-dimensional lattice Boltzmann model for immiscible two-phase flow simulations. Phys. Rev. E, 85:046309, 2012.] based on a concept of continuum surface force, is improved to simulate immiscible two-phase flows in porous media. The new improvements allow the model to account for different kinematic viscosities of both fluids and to model fluid-solid interactions. The capability and accuracy of this model is first validated by two benchmark tests: a layered two-phase flow with a viscosity ratio, and a dynamic capillary intrusion. This model is then used to simulate liquid CO2 (LCO2) displacing water in a dual-permeability pore network. The extent and behavior of LCO2 preferential flow (i.e., fingering) is found to depend on the capillary number (Ca), and three different displacement patterns observed in previous micromodel experiments are reproduced. The predicted variation of LCO2 saturation with Ca, as well as variation of specific interfacial length with LCO2 saturation, are both in good agreement with the experimental observations. To understand the effect of heterogeneity on pore-scale displacement, we also simulate LCO2 displacing water in a randomly heterogeneous pore network, which has the same size and porosity as the dual-permeability pore network. In comparison to the dual-permeability case, the transition from capillary fingering to viscous fingering occurs at a higher Ca, and LCO2 saturation is higher at low Ca but lower at high Ca. In either pore network, the LCO2-water specific interfacial length is found to obey a power-law dependence on LCO2 saturation.

  15. Race to Displace: A Game to Model the Effects of Invasive Species on Plant Communities

    ERIC Educational Resources Information Center

    Hopwood, Jennifer L.; Flowers, Susan K.; Seidler, Katie J.; Hopwood, Erica L.

    2013-01-01

    Invasive species are a substantial threat to biodiversity. Educating students about invasive species introduces fundamental concepts in biology, ecology, and environmental science. In the Race to Displace game, students assume the characteristics of select native or introduced plants and experience first hand the influences of species interactions…

  16. Toward Energetically Consistent Parameterization of Horizontal and Vertical Sub-Grid Mixing for High-Resolution NWP Models

    NASA Astrophysics Data System (ADS)

    Bao, Jian-Wen; Grell, Eveyn; Michelson, Sara

    2013-04-01

    All numerical weather prediction (NWP) models require parameterizations of sub-grid turbulent mixing in both horizontal and vertical directions. Traditionally, due to the high aspect ratio between the horizontal and vertical dimensions of grids used in NWP models, it is assumed that the parameterizations of horizontal and vertical sub-grid mixing can be parameterized separately and most research efforts in the NWP community to parameterize sub-grid turbulent mixing has been focused on the vertical sub-grid turbulent mixing in the planetary boundary layer (PBL). Consequently, the parameterized vertical sub-grid mixing is formulated according to the vertical mixing theory in the PBL, while the parameterized horizontal sub-grid turbulent mixing in NWP models is formulated to be dependent on the grid-resolved strain rate and used mostly as numerical tuning parameter. Such a framework of parameterizing sub-grid turbulent mixing has a fundamental drawback: the conversion of grid-scale kinetic energy (KE) to sub-grid turbulent kinetic energy (TKE) is not consistently constrained between the vertical and horizontal directions. As the resolution of NWP models increases steadily, such that grid spacing becomes comparable to the typical size of largest energy-containing eddies, a more general and energetically consistent treatment of horizontal and vertical sub-grid turbulent mixing is required to overcome the drawback of the traditional parameterization approach. This presentation highlights major results from a series of sensitivity experiments with the Advanced Research WRF (ARW) model that were carried out for the purpose of comparing and evaluating a more general and energetically consistent parameterization of horizontal and vertical sub-grid turbulent mixing with two traditional schemes for parameterizing vertical sub-grid turbulent mixing in NWP models that share the same strain-rate-dependent parameterization for horizontal sub-grid turbulent mixing: the K

  17. Atmospheric Test Models and Numerical Experiments for the Simulation of the Global Distributions of Weather Data Transponders III. Horizontal Distributions

    SciTech Connect

    Molenkamp, C.R.; Grossman, A.

    1999-12-20

    A network of small balloon-borne transponders which gather very high resolution wind and temperature data for use by modern numerical weather predication models has been proposed to improve the reliability of long-range weather forecasts. The global distribution of an array of such transponders is simulated using LLNL's atmospheric parcel transport model (GRANTOUR) with winds supplied by two different general circulation models. An initial study used winds from CCM3 with a horizontal resolution of about 3 degrees in latitude and longitude, and a second study used winds from NOGAPS with a 0.75 degree horizontal resolution. Results from both simulations show that reasonable global coverage can be attained by releasing balloons from an appropriate set of launch sites.

  18. Analysis of the impact of Seasat scatterometer data and horizontal resolution on GLA model simulations of the QE II storm

    NASA Technical Reports Server (NTRS)

    Lenzen, Allen J.; Johnson, Donald R.; Atlas, Robert

    1993-01-01

    The impact of the Seasat-A satellite scatterometer wind data and the increased horizontal resolution on the Goddard Laboratory for Atmospheres model predictions of the Queen Elizabeth II (QE II) storm of 9-11 September 1978 was evaluated for four different GLA model simulations of the QE II storm. It is shown that the largest impact on the simulation was caused by doubling the model's horizontal resolution from 4 deg x 5 deg to 2 deg x 2.5 deg. The increased resolution resulted in a storm track which was much closer to the one observed, with a much deeper surface development, a stronger mass circulation, stronger heating, and stronger increase of angular momentum.

  19. Dynamics modeling and periodic control of horizontal-axis wind turbines

    NASA Astrophysics Data System (ADS)

    Stol, Karl Alexander

    2001-07-01

    The development of large multi-megawatt wind turbines has increased the need for active feedback control to meet multiple performance objectives. Power regulation is still of prime concern but there is an increasing interest in mitigating loads for these very large, dynamically soft and highly integrated power systems. This work explores the opportunities for utilizing state space modeling, modal analysis, and multi-objective controllers in advanced horizontal-axis wind turbines. A linear state-space representation of a generic, multiple degree-of-freedom wind turbine is developed to test various control methods and paradigms. The structural model, SymDyn, provides for limited flexibility in the tower, drive train and blades assuming a rigid component architecture with joint springs and dampers. Equations of motion are derived symbolically, verified by numerical simulation, and implemented in the Matlab with Simulink computational environment. AeroDyn, an industry-standard aerodynamics package for wind turbines, provides the aerodynamic load data through interfaced subroutines. Linearization of the structural model produces state equations with periodic coefficients due to the interaction of rotating and non-rotating components. Floquet theory is used to extract the necessary modal properties and several parametric studies identify the damping levels and dominant dynamic coupling influences. Two separate issues of control design are investigated: full-state feedback and state estimation. Periodic gains are developed using time-varying LQR techniques and many different time-invariant control designs are constructed, including a classical PID controller. Disturbance accommodating control (DAC) allows the estimation of wind speed for minimization of the disturbance effects on the system. Controllers are tested in simulation for multiple objectives using measurement of rotor position and rotor speed only and actuation of independent blade pitch. It is found that

  20. An Analytical Model for Simulating Heavy-Oil Recovery by Cyclic Steam Injection Using Horizontal Wells, SUPRI TR-118

    SciTech Connect

    Diwan, Utpal; Kovscek, Anthony R.

    1999-08-09

    In this investigation, existing analytical models for cyclic steam injection and oil recovery are reviewed and a new model is proposed that is applicable to horizontal wells. A new flow equation is developed for oil production during cyclic steaming of horizontal wells. The model accounts for the gravity-drainage of oil along the steam-oil interface and through the steam zone. Oil viscosity, effective permeability, geometry of the heated zone, porosity, mobile oil saturation, and thermal diffusivity of the reservoir influence the flow rate of oil in the model. The change in reservoir temperature with time is also modeled, and it results in the expected decline in oil production rate during the production cycle as the reservoir cools. Wherever appropriate, correlations and incorporated to minimize data requirements. A limited comparison to numerical simulation results agrees well, indicating that essential physics are successfully captured. Cyclic steaming appears to be a systematic met hod for heating a cold reservoir provided that a relatively uniform distribution of steam is obtained along the horizontal well during injection. A sensitivity analysis shows that the process is robust over the range of expected physical parameters.

  1. Estimation of confidence intervals of global horizontal irradiance obtained from a weather prediction model

    NASA Astrophysics Data System (ADS)

    Ohtake, Hideaki; Gari da Silva Fonseca, Joao, Jr.; Takashima, Takumi; Oozeki, Takashi; Yamada, Yoshinori

    2014-05-01

    Many photovoltaic (PV) systems have been installed in Japan after the introduction of the Feed-in-Tariff. For an energy management of electric power systems included many PV systems, the forecast of the PV power production are useful technology. Recently numerical weather predictions have been applied to forecast the PV power production while the forecasted values invariably have forecast errors for each modeling system. So, we must use the forecast data considering its error. In this study, we attempted to estimate confidence intervals for hourly forecasts of global horizontal irradiance (GHI) values obtained from a mesoscale model (MSM) de-veloped by the Japan Meteorological Agency. In the recent study, we found that the forecasted values of the GHI of the MSM have two systematical forecast errors; the first is that forecast values of the GHI are depended on the clearness indices, which are defined as the GHI values divided by the extraterrestrial solar irradiance. The second is that forecast errors have the seasonal variations; the overestimation of the GHI forecasts is found in winter while the underestimation of those is found in summer. The information of the errors of the hourly GHI forecasts, that is, confidence intervals of the forecasts, is of great significance for planning the energy management included a lot of PV systems by an electric company. On the PV systems, confidence intervals of the GHI forecasts are required for a pinpoint area or for a relatively large area control-ling the power system. For the relatively large area, a spatial-smoothing method of the GHI values is performed for both the observations and forecasts. The spatial-smoothing method caused the decline of confidence intervals of the hourly GHI forecasts on an extreme event of the GHI forecast (a case of large forecast error) over the relatively large area of the Tokyo electric company (approximately 68 % than for a pinpoint forecast). For more credible estimation of the confidence

  2. Dynamics of the head-neck complex in response to the trunk horizontal vibration: modeling and identification.

    PubMed

    Fard, Mohammad A; Ishihara, Tadashi; Inooka, Hikaru

    2003-08-01

    Although many studies exist concerning the influence of seat vibration on the head in the seated human body, the dynamic response of the head-neck complex (HNC) to the trunk vibration has not been well investigated. Little quantitative knowledge exists about viscoelastic parameters of the neck. In this study, the dynamics of the HNC is identified when it is exposed to the trunk horizontal (fore-and-aft) vibration. The frequency response functions between the HNC angular velocity and the trunk horizontal acceleration, corresponding to four volunteers, are obtained in the frequency range of 0.5 Hz to 10 Hz. A fourth-order mathematical model, derived by considering a double-inverted-pendulum model for the HNC, is designed to simulate the dynamic response of the HNC to the trunk horizontal vibration. The frequency domain identification method is used to determine the coefficients of the mathematical model of the HNC. Good agreement has been obtained between experimental and simulation results. This indicates that the system, similar to the designed fourth-order model, has mainly two resonance frequencies. The viscoelastic parameters of the neck, including the spring and damping coefficients, are then obtained by use of the optimization method. PMID:12968578

  3. Implementation of a random displacement method (RDM) in the ADPIC model framework

    SciTech Connect

    Ermak, D.L.; Nasstrom, J.S.; Taylor, A.G.

    1995-06-01

    The objective of this work was to implement a 3-D Lagrangian stochastic (also called random walk or Monte Carlo) diffusion method in the framework of the operational ADPIC (Atmospheric Diffusion Particle-In-Cell) code. The Random Displacement Method, RDM, presented here and implemented in the ADPIC code, calculates atmospheric dispersion in a purely Lagrangian, grid-independent manner. Some of the benefits of this approach compared to the previously-used ``particle-in-cell, gradient diffusion`` method are (a) a sub-grid diffusion approximation is no longer needed, (b) numerical accuracy of the diffusion calculation is improved because particle displacement does not depend on the resolution of the Eulerian grid used to calculate species concentration, and (c) adaptation to other grid structures for the input wind field does not affect the diffusion calculation. In addition, the RDM incorporates a unique and accurate treatment of particle interaction with the surface.

  4. Hydrodynamic analysis of the displacement conditions of formation fluids using an axisymmetric model

    NASA Astrophysics Data System (ADS)

    Chernoshchuk, I. B.

    2008-03-01

    The axisymmetric problem of the displacement of formation fluids by a drilling mud filtrate with filter cake formation is considered. An analysis is made of the distribution and variation of the main parameters of the process: filtrate volume, filter cake thickness, oil saturation, and pressure. The positions of the water-saturation and salt-concentration fronts are determined. The results are compared with the geophysical logging data for straight-hole drilling.

  5. A simple physical model for steam absorption into a falling film of aqueous lithium bromide solution on a horizontal tube

    NASA Astrophysics Data System (ADS)

    Auracher, Hein; Wohlfeil, Arnold; Ziegler, Felix

    2008-03-01

    For one horizontal tube in an absorber the Nusselt solution for film thickness and velocity distribution was applied, assuming steady state in heat transfer and a semi-infinite body’s concentration profile with unsteady state mass transfer. The model was applied to the absorption of steam into aqueous lithium bromide in absorption chillers. The results are compared to published experimental values and show fair agreement.

  6. Nuclear component horizontal seismic restraint

    DOEpatents

    Snyder, Glenn J.

    1988-01-01

    A nuclear component horizontal seismic restraint. Small gaps limit horizontal displacement of components during a seismic occurrence and therefore reduce dynamic loadings on the free lower end. The reactor vessel and reactor guard vessel use thicker section roll-forged rings welded between the vessel straight shell sections and the bottom hemispherical head sections. The inside of the reactor guard vessel ring forging contains local vertical dovetail slots and upper ledge pockets to mount and retain field fitted and installed blocks. As an option, the horizontal displacement of the reactor vessel core support cone can be limited by including shop fitted/installed local blocks in opposing alignment with the reactor vessel forged ring. Beams embedded in the wall of the reactor building protrude into apertures in the thermal insulation shell adjacent the reactor guard vessel ring and have motion limit blocks attached thereto to provide to a predetermined clearance between the blocks and reactor guard vessel ring.

  7. Assimilation of scalar versus horizontal gradient information from the VAS into a mesoscale model

    NASA Technical Reports Server (NTRS)

    Diak, George

    1987-01-01

    Comparisons are made between analyses and forecasts which incorporate VAS geopotential data as either scalar or horizontal gradient information for a case study on the AVE/VAS day of Mar. 6, 1982. On this day, incorporating the VAS information in analysis as a variational constraint on horizontal geopotential gradients significantly mitigated the effects of large data biases which made VAS assimilation by standard scalar methods very difficult. A subsequent forecast made from the gradient assimilation was superior to one made from the standard analysis and of comparable quality in geopotentials to a control forecast from synoptic data. Most impact was noted in the forecasts of vertical motion and precipitation in the gradient vs this control simulation.

  8. Ballistics Model for Particles on a Horizontal Plane in a Vacuum Propelled by a Vertically Impinging Gas Jet

    NASA Technical Reports Server (NTRS)

    Lane, J. E.; Metzger, P. T.

    2010-01-01

    A simple trajectory model has been developed and is presented. The particle trajectory path is estimated by computing the vertical position as a function of the horizontal position using a constant horizontal velocity and a vertical acceleration approximated as a power law. The vertical particle position is then found by solving the differential equation of motion using a double integral of vertical acceleration divided by the square of the horizontal velocity, integrated over the horizontal position. The input parameters are: x(sub 0) and y(sub 0), the initial particle starting point; the derivative of the trajectory at x(sub 0) and y(sub 0), s(sub 0) = s(x(sub 0))= dx(y)/dy conditional expectation y = y((sub 0); and b where bx(sub 0)/y(sub 0) is the final trajectory angle before gravity pulls the particle down. The final parameter v(sub 0) is an approximation to a constant horizontal velocity. This model is time independent, providing vertical position x as a function of horizontal distance y: x(y) = (x(sub 0) + s(sub 0) (y-y(sub 0))) + bx(sub 0) -(s(sub 0)y(sub 0) ((y - y(sub 0)/y(sub 0) - ln((y/y(sub 0)))-((g(y-y(sub 0)(exp 2))/ 2((v(sub 0)(exp 2). The first term on the right in the above equation is due to simple ballistics and a spherically expanding gas so that the trajectory is a straight line intersecting (0,0), which is the point at the center of the gas impingement on the surface. The second term on the right is due to vertical acceleration, which may be positive or negative. The last term on the right is the gravity term, which for a particle with velocities less than escape velocity will eventually bring the particle back to the ground. The parameters b, s(sub 0), and in some cases v(sub 0), are taken from an interpolation of similar parameters determined from a CFD simulation matrix, coupled with complete particle trajectory simulations.

  9. Analysis of condensation on a horizontal cylinder with unknown wall temperature and comparison with the Nusselt model of film condensation

    NASA Technical Reports Server (NTRS)

    Bahrami, Parviz A.

    1996-01-01

    Theoretical analysis and numerical computations are performed to set forth a new model of film condensation on a horizontal cylinder. The model is more general than the well-known Nusselt model of film condensation and is designed to encompass all essential features of the Nusselt model. It is shown that a single parameter, constructed explicitly and without specification of the cylinder wall temperature, determines the degree of departure from the Nusselt model, which assumes a known and uniform wall temperature. It is also known that the Nusselt model is reached for very small, as well as very large, values of this parameter. In both limiting cases the cylinder wall temperature assumes a uniform distribution and the Nusselt model is approached. The maximum deviations between the two models is rather small for cases which are representative of cylinder dimensions, materials and conditions encountered in practice.

  10. An evaluation of two millimeter wave propagation models for horizontal atmospheric attenuation at 70-115 GHZ

    NASA Astrophysics Data System (ADS)

    Vogel, Gerard N.

    1988-02-01

    An evaluation is performed for two millimeter wave propagation models: the LIEBE model, developed at the Institute for Telecommunications, Boulder, CO, under the guidance of Dr. H. Liebe; and the EOSAEL model, developed at the U. S. Army Atmospheric Laboratory at White Sands Missile Range, NM. This evaluation is conducted for horizontal attenuation due to both clear atmosphere and hydrometer effects under typical surface meteorological conditions, and within the frequency range 70-115 GHz. Intercomparisons of model theories and predictions show slight differences for molecular oxygen and fog attenuations, but significant differences for water vapor and rain attenuations. Results indicate that, while the qualitative agreement between either the EOSAEL or LIEBE model predictions, and measurements, for horizontal attenuation due to oxygen, water vapor, fog and rain is certainly satisfactory, there is a definite need for improvement. Overall, no clear preference for either the EOSAEL or LIEBE model for operational use is ascertained. Data comparisons suggest that, for several attenuation types, model preference is dependent on either the frequency or meteorological conditions.

  11. Dissipation and displacement of hotspots in reaction-diffusion models of crime.

    PubMed

    Short, Martin B; Brantingham, P Jeffrey; Bertozzi, Andrea L; Tita, George E

    2010-03-01

    The mechanisms driving the nucleation, spread, and dissipation of crime hotspots are poorly understood. As a consequence, the ability of law enforcement agencies to use mapped crime patterns to design crime prevention strategies is severely hampered. We also lack robust expectations about how different policing interventions should impact crime. Here we present a mathematical framework based on reaction-diffusion partial differential equations for studying the dynamics of crime hotspots. The system of equations is based on empirical evidence for how offenders move and mix with potential victims or targets. Analysis shows that crime hotspots form when the enhanced risk of repeat crimes diffuses locally, but not so far as to bind distant crime together. Crime hotspots may form as either supercritical or subcritical bifurcations, the latter the result of large spikes in crime that override linearly stable, uniform crime distributions. Our mathematical methods show that subcritical crime hotspots may be permanently eradicated with police suppression, whereas supercritical hotspots are displaced following a characteristic spatial pattern. Our results thus provide a mechanistic explanation for recent failures to observe crime displacement in experimental field tests of hotspot policing. PMID:20176972

  12. Modeling and experiment of the suspended seismometer concept for attenuating the contribution of tilt motion in horizontal measurements.

    PubMed

    Matichard, F; Evans, M; Mittleman, R; MacInnis, M; Biscans, S; Dooley, K L; Sohier, H; Lauriero, A; Paris, H; Koch, J; Knothe, P; Carbajo, A; Dufort, C

    2016-06-01

    Tilt-horizontal coupling in inertial sensors limits the performance of active isolation systems such as those used in gravitational wave detectors. Inertial rotation sensors can be used to subtract the tilt component from the signal produced by horizontal inertial sensors, but such techniques are often limited by the sensor noise of the tilt measurement. A different approach is to mechanically filter the tilt transmitted to the horizontal inertial sensor, as discussed in this article. This technique does not require an auxiliary rotation sensor and can produce a lower noise measurement. The concept investigated uses a mechanical suspension to isolate the inertial sensor from input tilt. Modeling and simulations show that such a configuration can be used to adequately attenuate the tilt transmitted to the instrument, while maintaining translation sensitivity in the frequency band of interest. The analysis is supported by experimental results showing that this approach is a viable solution to overcome the tilt problem in the field of active inertial isolation. PMID:27370484

  13. Modeling emissivity of low-emissivity coating containing horizontally oriented metallic flake particles

    NASA Astrophysics Data System (ADS)

    Chen, Shuai; Yuan, Le; Weng, Xiaolong; Deng, Longjiang

    2014-11-01

    The scattering and absorption cross sections of horizontally oriented metallic flake particles are estimated by extended geometric optics that includes diffraction and edge effects. Emissivity of the coating containing those particles is calculated using Kubelka-Munk theory. The dependence of emissivity of the coating on the radius, thickness, content of metallic flake particles and coating thickness is discussed. Finally, theoretical results are compared with the experimental measurements with Al/acrylic resin coating system and the results show that simulation values are in good agreement with experimental ones.

  14. An efficient horizontal advection scheme for the modeling of global transport of constituents

    SciTech Connect

    Hundsdorfer, W.; Spee, E.J.

    1995-12-01

    In this paper the authors consider a dimensional-splitting scheme for horizontal advection on a sphere with a uniform longitude-latitude grid. The 1D subprocesses that arise within the splitting are solved with an explicit finite-volume type scheme, which is made unconditionally stable by allowing the stencil to vary with the Courant numbers. The scheme is made positive by flux limiting. For the inaccuracies at the poles some special measures are discussed. Numerical tests show that the scheme is almost shape preserving and conservative, and it gives accurate results at low computational costs. 23 refs., 7 figs., 1 tab.

  15. Modeling the Impact of Fracture Growth on Fluid Displacements in Deformable Porous Media

    NASA Astrophysics Data System (ADS)

    Santillán, D.; Cueto-Felgueroso, L.; Juanes, R.

    2015-12-01

    Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The flow of a fluid through a deformable porous media is present in manyenvironmental, industrial, and biological processes,such as the removal of pollutants from underground water bodies, enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. However, the injection of a fluid can generate or propagate fractures, which are preferential flow paths. Using numerical simulation, we study the interplay between injection and rock mechanics, and elucidate fracture propagation as a function of injection rate, initial crack topology and mechanical rock properties. Finally, we discuss the role of fracture growth on fluid displacements in porous media. Figure: An example of fracture (in red) propagated in a porous media (in blue)

  16. Modeling the Impact of Deformation on Unstable Miscible Displacements in Porous Media

    NASA Astrophysics Data System (ADS)

    Santillán, D.; Cueto-Felgueroso, L.

    2014-12-01

    Coupled flow and geomechanics is a critical research challenge in engineering and the geosciences. The simultaneous flow of two or more fluids with different densities or viscosities through deformable media is ubiquitous in environmental, industrial, and biological processes, including the removal of non-aqueous phase liquids from underground water bodies, the geological storage of CO2, and current challenges in energy technologies, such as enhanced geothermal systems, unconventional hydrocarbon resources or enhanced oil recovery techniques. Using numerical simulation, we study the interplay between viscous-driven flow instabilities (viscous fingering) and rock mechanics, and elucidate the structure of the displacement patterns as a function of viscosity contrast, injection rate and rock mechanical properties. Finally, we discuss the role of medium deformation on transport and mixing processes in porous media.

  17. Finite-difference modeling of the monopole acoustic logs in a horizontally stratified porous formation.

    PubMed

    Guan, Wei; Hu, Hengshan; He, Xiao

    2009-04-01

    Monopole acoustic logs in a homogeneous fluid-saturated porous formation can be simulated by the real-axis integration (RAI) method to analytically solve Biot's equations [(1956a) J. Acoust. Soc. Am. 28, 168-178; (1956b) J. Acoust. Soc. Am. 28, 179-191; (1962) J. Appl. Phys. 33, 1482-1498], which govern the wave propagation in poro-elastic media. Such analytical solution generally is impossible for horizontally stratified formations which are common in reality. In this paper, a velocity-stress finite-difference time-domain (FDTD) algorithm is proposed to solve the problem. This algorithm considers both the low-frequency viscous force and the high-frequency inertial force in poro-elastic media, extending its application to a wider frequency range compared to existing algorithms which are only valid in the low-frequency limit. The perfectly matched layer (PML) is applied as an absorbing boundary condition to truncate the computational region. A PML technique without splitting the fields is extended to the poro-elastic wave problem. The FDTD algorithm is validated by comparisons against the RAI method in a variety of formations with different velocities and permeabilities. The acoustic logs in a horizontally stratified porous formation are simulated with the proposed FDTD algorithm. PMID:19354370

  18. Influence of meteorological data and horizontal gradient of tropospheric model on precise point positioning

    NASA Astrophysics Data System (ADS)

    Xu, Yan; Jiang, Nan; Xu, Guochang; Yang, Yuanxi; Schuh, Harald

    2015-12-01

    Using GPT2 derived meteorological data and actual meteorological observations can achieve the same positioning precision in the most areas worldwide except for the Antarctic region. However, the improvement of the actual meteorological observations on the positioning result is significant comparing to using GPT2 derived meteorological data in Antarctic. In the case of 5° elevation cut-off angle, the height precision can be improved by 25%. Furthermore, when the elevation cut-off angle is lower, the effect of the actual meteorological observations on the positioning precision is more significant in Antarctic due to the retention of low elevation angle observations. This study also shows that the influence of tropospheric horizontal gradient correction can improve the PPP precision. Under the lower elevation cut-off angle and higher humidity conditions, especially in summer time and low-latitudes area, the usefulness of the horizontal gradient correction is remarkable. The average improvement of N, E and U directions can reach up to 51%, 15% and 30%, respectively.

  19. The effect of horizontal resolution on simulation quality in the Community Atmospheric Model, CAM5.1

    SciTech Connect

    Wehner, Michael F.; Reed, Kevin A.; Li, Fuyu; Prabhat, -; Bacmeister, Julio; Chen, Cheng -Ta; Paciorek, Christopher; Gleckler, Peter J.; Sperber, Kenneth R.; Collins, William D.; Gettelman, Andrew; Jablonowski, Christiane

    2014-11-05

    We present an analysis of version 5.1 of the Community Atmospheric Model (CAM5.1) at a high horizontal resolution. Intercomparison of this global model at approximately 0.25°, 1°, and 2° is presented for extreme daily precipitation as well as for a suite of seasonal mean fields. In general, extreme precipitation amounts are larger in high resolution than in lower-resolution configurations. In many but not all locations and/or seasons, extreme daily precipitation rates in the high-resolution configuration are higher and more realistic. The high-resolution configuration produces tropical cyclones up to category 5 on the Saffir-Simpson scale and a comparison to observations reveals both realistic and unrealistic model behavior. In the absence of extensive model tuning at high resolution, simulation of many of the mean fields analyzed in this study is degraded compared to the tuned lower-resolution public released version of the model.

  20. Equilibrium form of horizontally retreating, soil-mantled hillslopes: Model development and application to a groundwater sapping landscape

    NASA Astrophysics Data System (ADS)

    Perron, J. Taylor; Hamon, Jennifer L.

    2012-03-01

    We present analytical solutions for the steady state topographic profile of a soil-mantled hillslope retreating into a level plain in response to a horizontally migrating base level. This model applies to several scenarios that commonly arise in landscapes, including widening valleys, eroding channel banks, and retreating scarps. For a sediment transport law in which sediment flux is linearly proportional to the topographic slope, the steady state profile is exponential, with an e-folding length, L, proportional to the ratio of the sediment transport coefficient to the base level migration speed. For the case in which sediment flux increases nonlinearly with slope, the solution has a similar form that converges to the linear case as L increases. We use a numerical model to explore the effects of different base level geometries and find that the one-dimensional analytical solution is a close approximation for the hillslope profile above an advancing channel tip. We then compare the analytical model with hillslope profiles above the tips of a groundwater sapping channel network in the Florida Panhandle. The model agrees closely with hillslope profiles measured from airborne laser altimetry, and we use a predicted log linear relationship between topographic slope and horizontal distance to estimate L for the measured profiles. Mapping 1/L over channel tips throughout the landscape reveals that adjacent channel networks may be growing at different rates and that south facing slopes experience more efficient hillslope transport.

  1. Comparison of numerical approaches for modeling gravitationally-induced horizontal deviatoric stresses within a Hawaiian basaltic shield volcano

    NASA Astrophysics Data System (ADS)

    Klein, E. C.; Le Corvec, N.; Galgana, G.

    2014-12-01

    Basaltic shield volcanoes are subjected to important gravitational loads that lead to their spreading. Such deformation influences the stress state within the volcano, thus the formation of faults and the location of earthquakes and the propagation of magmas and the potential eruption location. Using distinct numerical approaches constrained by geophysical data from the Hawai`i Island Shield Volcano (HISV), we studied the extent to which horizontal deviatoric stresses (HDS) induced from gravitational loading drives the process of volcanic spreading. Two distinct numerical approaches based on similar models were used: 1- the thin-sheet method, and 2- finite element models using COMSOL Multiphysics. We quantified depth integrals of vertical stress (i.e., the gravitational potential energy per unit area or GPE) and then we derived the HDS that balance the horizontal gradients in GPE. We performed the integration over series of single layers that encompasses the surface of variable topography down to a uniform depth of 10 km b.s.l. consistent with the base of the HISV. To compare the results of our numerical approaches we built a fine-scale, Island-wide, set of kinematically constrained deformation indicators (KCDI) using the slip-rate and fault style information from a comprehensive fault database for the HISV. We measure the success of each numerical approach by how well model HDS match the horizontal styles of the strain rates associated with KCDI. Thus far we find that the HDS obtained using the thin-sheet method match well with the KCDI. This may indicate that to first order that patterns of observed surface deformation on the HISV are governed by gradients in GPE. This provides a balance to the gravitationally-induced stresses associated with the volcano load. These HDS do not account for other competing sources of stress (e.g., flexure, magmatic, or hoop) that taken all together may combine to better explain the volcano spreading process for basaltic shield type

  2. Modeling the MJO rain rates using parameterized large scale dynamics: vertical structure, radiation, and horizontal advection of dry air

    NASA Astrophysics Data System (ADS)

    Wang, S.; Sobel, A. H.; Nie, J.

    2015-12-01

    Two Madden Julian Oscillation (MJO) events were observed during October and November 2011 in the equatorial Indian Ocean during the DYNAMO field campaign. Precipitation rates and large-scale vertical motion profiles derived from the DYNAMO northern sounding array are simulated in a small-domain cloud-resolving model using parameterized large-scale dynamics. Three parameterizations of large-scale dynamics --- the conventional weak temperature gradient (WTG) approximation, vertical mode based spectral WTG (SWTG), and damped gravity wave coupling (DGW) --- are employed. The target temperature profiles and radiative heating rates are taken from a control simulation in which the large-scale vertical motion is imposed (rather than directly from observations), and the model itself is significantly modified from that used in previous work. These methodological changes lead to significant improvement in the results.Simulations using all three methods, with imposed time -dependent radiation and horizontal moisture advection, capture the time variations in precipitation associated with the two MJO events well. The three methods produce significant differences in the large-scale vertical motion profile, however. WTG produces the most top-heavy and noisy profiles, while DGW's is smoother with a peak in midlevels. SWTG produces a smooth profile, somewhere between WTG and DGW, and in better agreement with observations than either of the others. Numerical experiments without horizontal advection of moisture suggest that that process significantly reduces the precipitation and suppresses the top-heaviness of large-scale vertical motion during the MJO active phases, while experiments in which the effect of cloud on radiation are disabled indicate that cloud-radiative interaction significantly amplifies the MJO. Experiments in which interactive radiation is used produce poorer agreement with observation than those with imposed time-varying radiative heating. Our results highlight the

  3. Measurements of the Buffeting Loads on the Wing and Horizontal Tail of a 1/4-scale Model of the X-1E Airplane

    NASA Technical Reports Server (NTRS)

    Rainey, A Gerald; Igoe, William B

    1958-01-01

    The buffeting loads acting on the wing and horizontal tail of a 1/4-scale model of the X-1E airplane have been measured in the Langley 16-foot transonic tunnel in the Mach number range from 0.40 to 0.90. When the buffeting loads were reduced to a nondimensional aerodynamic coefficient of buffeting intensity, it was found that the maximum buffeting intensity of the horizontal tail was about twice as large as that of the wing. Comparison of power spectra of buffeting loads acting on the horizontal tail of the airplaneand of the model indicated that the model horizontal tail, which was of conventional force-test-model design, responded in an entirely different mode than did the airplane.This result implied that if quantitative extrapolation of model data to flight conditions were desired a dynamically scaled model of the rearward portion of the fuselage and empennage would be required. A study of the sources of horizontal-tail buffeting of the model indicated that the wing wake contributed a large part of the total buffeting load. At one condition it was found that removal of the wing wake would reduce the buffeting loads on the horizontal tail to about one-third of the original value.

  4. Horizontal geometrical reaction time model for two-beam nacelle LiDARs

    NASA Astrophysics Data System (ADS)

    Beuth, Thorsten; Fox, Maik; Stork, Wilhelm

    2015-06-01

    Wind energy is one of the leading sustainable energies. To attract further private and state investment in this technology, a broad scaled drop of the cost of energy has to be enforced. There is a trend towards using Laser Doppler Velocimetry LiDAR systems for enhancing power output and minimizing downtimes, fatigue and extreme forces. Since most used LiDARs are horizontally setup on a nacelle and work with two beams, it is important to understand the geometrical configuration which is crucial to estimate reaction times for the actuators to compensate wind gusts. In the beginning of this article, the basic operating modes of wind turbines are explained and the literature on wind behavior is analyzed to derive specific wind speed and wind angle conditions in relation to the yaw angle of the hub. A short introduction to the requirements for the reconstruction of the wind vector length and wind angle leads to the problem of wind shear detection of angled but horizontal homogeneous wind fronts due to the spatial separation of the measuring points. A distance is defined in which the wind shear of such homogeneous wind fronts is not present which is used as a base to estimate further distance calculations. The reaction time of the controller and the actuators are having a negative effect on the effective overall reaction time for wind regulation as well. In the end, exemplary calculations estimate benefits and disadvantages of system parameters for wind gust regulating LiDARs for a wind turbine of typical size. An outlook shows possible future improvements concerning the vertical wind behavior.

  5. An advanced CFD model to study the effect of non-condensable gas on cavitation in positive displacement pumps

    NASA Astrophysics Data System (ADS)

    Iannetti, Aldo; Stickland, Matthew T.; Dempster, William M.

    2015-09-01

    An advanced transient CFD model of a positive displacement reciprocating pump was created to study its behavior and performance in cavitating condition during the inlet stroke. The "full" cavitation model developed by Singhal et al. was utilized, and a sensitivity analysis test on two air mass fraction amounts (1.5 and 15 parts per million) was carried out to study the influence of the dissolved air content in water on the cavitation phenomenon. The model was equipped with user defined functions to introduce the liquid compressibility, which stabilizes the simulation, and to handle the two-way coupling between the pressure field and the inlet valve lift history. Estimation of the performance is also presented in both cases.

  6. The effect of horizontal resolution on cloud radiative forcing in the ECMWF model. PCMDI report No. 22

    SciTech Connect

    Potter, G.L.

    1995-05-01

    With expanding computer capability and capacity there has been considerable interest in increasing the resolution in GCMs. The primary driving force behind this are two fold: (1) increased resolution may reduce the systematic errors inherent in parameterization of sub-grid scale processes, and (2) higher resolution may improve confidence in regional scale studies of climatic features that are orographically influenced -- such as the effect of the Tibetan Plateau on the East Asian Monsoon. This study focuses on the effect of horizontal resolution on the spatial and temporal systematic errors of cloud radiative forcing and its components. In this paper, the top-of-the-atmosphere radiation fields are taken from a series of simulations using the European Centre for Medium Range Forecasts (ECMWF) general circulation model (cycle 33), run at four different horizontal resolutions. Section 2 discusses the concept of cloud radiative forcing and describes the simulations from the ECMWF model. The observed global field of cloud forcing from ERBE is presented in section 3 along with the model-produced fields of the net solar and longwave cloud forcing. The seasonal effect of forcing is described in section 4, and the results are summarized in section 5.

  7. Numerical solution of the moving boundary-value problem based on the model of piston-like oil displacement

    NASA Astrophysics Data System (ADS)

    Astafev, Vladimir; Kasatkin, Andrey

    2016-06-01

    Prediction of the motion of the oil-water contact boundary has great importance in the problems of design of oilfield development by flooding. In this paper we consider a piston-like model of oil-water displacement, which takes into account differences in viscosity and density of the two fluids. Oil reservoir assumed to be homogeneous and infinite, fixed thickness, with constant values of porosity and permeability coefficients. Filtration of liquids is described by Darcy's law. It is assumed, that both fluids are weakly compressible and the pressure in the reservoir satisfies the quasi-stationary diffusion equation. Piston-like displacement model leads to the discontinuity of the tangential component of the velocity vector at the boundary of oil-water contact. Use the Cauchy integral reduces the problem of finding the current boundaries of oil-water contact to the system of singular integral equations for the tangential and normal components of the velocity vector and the Cauchy problem for the integration of the differential equations of motion of the boundary of oil-water contact. An algorithm for the numerical solution of this problem is developed. The monitoring of oil-water boundary motion for different regular and irregular schemes of flooding is carried out.

  8. Effect of Leukocyte-Rich and Platelet-Rich Plasma on Healing of a Horizontal Medial Meniscus Tear in a Rabbit Model

    PubMed Central

    Shin, Kyun Ho; Lee, Haseok; Kang, Seonghyun; Ko, You-Jin; Lee, Seung-Yup; Park, Jung-Ho; Bae, Ji-Hoon

    2015-01-01

    There are limited reports on the effect of platelet-rich plasma (PRP) on meniscus healing. The purpose of this study was to investigate the effect of leukocyte-rich PRP (L-PRP) on potential healing of the horizontal medial meniscus tears in a rabbit model. A horizontal medial meniscus tear was created in both knees of nine skeletally mature adult rabbits. Left or right knees were randomly assigned to a L-PRP group, or a control group. 0.5 mL of L-PRP from 10 mL of each rabbit's whole blood was prepared and injected into the horizontal tears in a L-PRP group. None was applied to the horizontal tears in a control group. The histological assessment of meniscus healing was performed at two, four, and six weeks after surgery. We found that there were no significant differences of quantitative histologic scoring between two groups at 2, 4, and 6 weeks after surgery (p > 0.05). This study failed to show the positive effect of single injection of L-PRP on enhancing healing of the horizontal medial meniscus tears in a rabbit model. Single injection of L-PRP into horizontal meniscus tears may not effectively enhance healing of horizontal medial meniscus tears. PMID:26180783

  9. Effect of Leukocyte-Rich and Platelet-Rich Plasma on Healing of a Horizontal Medial Meniscus Tear in a Rabbit Model.

    PubMed

    Shin, Kyun Ho; Lee, Haseok; Kang, Seonghyun; Ko, You-Jin; Lee, Seung-Yup; Park, Jung-Ho; Bae, Ji-Hoon

    2015-01-01

    There are limited reports on the effect of platelet-rich plasma (PRP) on meniscus healing. The purpose of this study was to investigate the effect of leukocyte-rich PRP (L-PRP) on potential healing of the horizontal medial meniscus tears in a rabbit model. A horizontal medial meniscus tear was created in both knees of nine skeletally mature adult rabbits. Left or right knees were randomly assigned to a L-PRP group, or a control group. 0.5 mL of L-PRP from 10 mL of each rabbit's whole blood was prepared and injected into the horizontal tears in a L-PRP group. None was applied to the horizontal tears in a control group. The histological assessment of meniscus healing was performed at two, four, and six weeks after surgery. We found that there were no significant differences of quantitative histologic scoring between two groups at 2, 4, and 6 weeks after surgery (p > 0.05). This study failed to show the positive effect of single injection of L-PRP on enhancing healing of the horizontal medial meniscus tears in a rabbit model. Single injection of L-PRP into horizontal meniscus tears may not effectively enhance healing of horizontal medial meniscus tears. PMID:26180783

  10. Slip reactivation model for the 2011 Mw9 Tohoku earthquake: Dynamic rupture, sea floor displacements and tsunami simulations.

    NASA Astrophysics Data System (ADS)

    Galvez, P.; Dalguer, L. A.; Rahnema, K.; Bader, M.

    2014-12-01

    The 2011 Mw9 Tohoku earthquake has been recorded with a vast GPS and seismic network given unprecedented chance to seismologists to unveil complex rupture processes in a mega-thrust event. In fact more than one thousand near field strong-motion stations across Japan (K-Net and Kik-Net) revealed complex ground motion patterns attributed to the source effects, allowing to capture detailed information of the rupture process. The seismic stations surrounding the Miyagi regions (MYGH013) show two clear distinct waveforms separated by 40 seconds. This observation is consistent with the kinematic source model obtained from the inversion of strong motion data performed by Lee's et al (2011). In this model two rupture fronts separated by 40 seconds emanate close to the hypocenter and propagate towards the trench. This feature is clearly observed by stacking the slip-rate snapshots on fault points aligned in the EW direction passing through the hypocenter (Gabriel et al, 2012), suggesting slip reactivation during the main event. A repeating slip on large earthquakes may occur due to frictional melting and thermal fluid pressurization effects. Kanamori & Heaton (2002) argued that during faulting of large earthquakes the temperature rises high enough creating melting and further reduction of friction coefficient. We created a 3D dynamic rupture model to reproduce this slip reactivation pattern using SPECFEM3D (Galvez et al, 2014) based on a slip-weakening friction with sudden two sequential stress drops . Our model starts like a M7-8 earthquake breaking dimly the trench, then after 40 seconds a second rupture emerges close to the trench producing additional slip capable to fully break the trench and transforming the earthquake into a megathrust event. The resulting sea floor displacements are in agreement with 1Hz GPS displacements (GEONET). The seismograms agree roughly with seismic records along the coast of Japan.The simulated sea floor displacement reaches 8-10 meters of

  11. Analytical determination of the reflection coefficient by the evanescent modes model during the wave-current-horizontal plate interaction

    NASA Astrophysics Data System (ADS)

    Errifaiy, Meriem; Naasse, Smail; Chahine, Chakib

    2016-07-01

    Our work presents an analytical study of the determination of the reflection coefficient during the interaction between the regular wave current and a horizontal plate. This study was done using the linearized potential flow theory with the evanescent modes model, while searching for complex solutions to the dispersion equation that are neither real pure nor imaginary pure. To validate the established model, it has been confronted with the experimental results of V. Rey and J. Touboul, in a first phase, and then compared to those of the numerical study by H.-X. Lin et al. Then, this model was used to study the effect of current on the reflection coefficient. xml:lang="fr"

  12. Field Demonstration of Horizontal Infill Drilling Using Cost-effective Integrated Reservoir Modeling--Mississippian Carbonates, Central Kansas

    SciTech Connect

    Saibal Bhattacharya

    2005-08-31

    constraints afflicting mature Mississippian fields. A publicly accessible databank of representative petrophysical properties and relationships was developed to overcome the paucity of such data that is critical to modeling the storage and flow in these reservoirs. Studies in 3 Mississippian fields demonstrated that traditional reservoir models built by integrating log, core, DST, and production data from existing wells on 40-acre spacings are unable to delineate karst-induced compartments, thus making 3D-seismic data critical to characterize these fields. Special attribute analyses on 3D data were shown to delineate reservoir compartments and predict those with pay porosities. Further testing of these techniques is required to validate their applicability in other Mississippian reservoirs. This study shows that detailed reservoir characterization and simulation on geomodels developed by integrating wireline log, core, petrophysical, production and pressure, and 3D-seismic data enables better evaluation of a candidate field for horizontal infill applications. In addition to reservoir compartmentalization, two factors were found to control the economic viability of a horizontal infill well in a mature Mississippian field: (a) adequate reservoir pressure support, and (b) an average well spacing greater than 40-acres.

  13. Ligand Displacement Reaction Paths in a Diiron Hydrogenase Active Site Model Complex.

    PubMed

    Blank, Jan H; Moncho, Salvador; Lunsford, Allen M; Brothers, Edward N; Darensbourg, Marcetta Y; Bengali, Ashfaq A

    2016-08-26

    The mechanism and energetics of CO, 1-hexene, and 1-hexyne substitution from the complexes (SBenz)2 [Fe2 (CO)6 ] (SBenz=SCH2 Ph) (1-CO), (SBenz)2 [Fe2 (CO)5 (η(2) -1-hexene)] (1-(η(2) -1-hexene)), and (SBenz)2 [Fe2 (CO)5 (η(2) -1-hexyne)] (1-(η(2) -1-hexyne)) were studied by using time-resolved infrared spectroscopy. Exchange of both CO and 1-hexyne by P(OEt)3 and pyridine, respectively, proceeds by a bimolecular mechanism. As similar activation enthalpies are obtained for both reactions, the rate-determining step in both cases is assumed to be the rotation of the Fe(CO)2 L (L=CO or 1-hexyne) unit to accommodate the incoming ligand. The kinetic profile for the displacement of 1-hexene is quite different than that for the alkyne and, in this case, both reaction channels, that is, dissociative (SN 1) and associative (SN 2), were found to be competitive. Because DFT calculations predict similar binding enthalpies of alkene and alkyne to the iron center, the results indicate that the bimolecular pathway in the case of the alkyne is lower in free energy than that of the alkene. In complexes of this type, subtle changes in the departing ligand characteristics and the nature of the mercapto bridge can influence the exchange mechanism, such that more than one reaction pathway is available for ligand substitution. The difference between this and the analogous study of (μ-pdt)[Fe(CO)3 ]2 (pdt=S(CH2 )3 S) underscores the unique characteristics of a three-atom S-S linker in the active site of diiron hydrogenases. PMID:27482938

  14. Transformed shoreline-following horizontal coordinates in a mesoscale model: A sea-land-breeze case study

    SciTech Connect

    Berri, G.J.; Nunez, M.N. Pabellon II Ciudad Universitaria, Buenos Aires )

    1993-05-01

    A hydrostatic and incompressible mesoscale model with transformed horizontal coordinates is presented. The model is applied to study the sea-land-breeze circulation over Rio de La Plata. One of the new coordinates is shoreline-following and the other one is locally quasi-perpendicular to the first one. The original set of equations in the Cartesian coordinates is rewritten in the curvilinear coordinates. This transformation is useful provided that the curvilinear coordinates are close to being orthogonal. The horizontal domain covers 250 km [times] 250 km, and the vertical domain is 2 km deep. To predict the sea-land-breeze circulation the model is integrated over 12 h. The forcing of the model is a cyclic perturbation of the surface temperature. The changes in the wind direction during the day are in good agreement with the observations from six weather stations in the region. The same program code is applied to uniform domains of different resolutions in order to test the coordinate transformation. Results show that the predictions based upon the variable-resolution version resemble ones obtained using high uniform resolution but consume only one-fourth the computer time needed by the latter. Comparison of the vertical velocity patterns predicted by the model to the cumulus clouds distribution observed from satellite images show a very good agreement too. The authors believe that all these results justify the use of the coordinate transformation in this type of model, although further verifications are needed in order to draw more definitive conclusions. 28 refs., 11 figs.

  15. The research of calibration method on lens-tilt displacement transmission-type system based on the aberration bounded model

    NASA Astrophysics Data System (ADS)

    Xu, Chun-mei; Liu, Bing-qi; Li, Li; Huang, Fu-yu; Zhang, Chu

    2015-10-01

    As the developing appliance range of high-resolution optical design, the requirement on the aberration of system design is becoming higher and higher, but the installation and adjustment error of optical components is an important element which influences the aberration. The decentration and tilt of optical components result not only the image lateral displacement but also the aberration enlargement of the optical system, the research on image quality of plane symmetric optical system is becoming more and more popular. The Gaussian correction methods on lens decentration already exist, but it is short of theoretical research to guide the correction on the lens tilt, which leads to the effect of image lateral displacement. This thesis analyzes theoretically a mathematical model between the lens tilt degree and wave aberration, and deduces mathematically the correction equation of zero aberration increment under the aberration constraint condition. Taking an example of some type optical sight, the ZEMAX simulation is carried out to validate this method, and the results show that: This method can effectively guide the correction of lens tilt, and reduce the influence of lens position change on the optical imaging quality. It has important practical significance to guide high-resolution optical design.

  16. Parameterization of PAR vertical profile within horizontally uniform forest canopies for use in environmental modeling

    NASA Astrophysics Data System (ADS)

    Lalic, Branislava; Firanj, Ana; Mihailovic, Dragutin T.; Podrascanin, Zorica

    2013-08-01

    radiation transfer within the forest canopy plays crucial role in energy balance and turbulent transfer processes. Objective of this study is to suggest a new relation for vertical profile of photosynthetically active radiation (PAR) in case of horizontally uniform forest canopy. It is based on (i) the Lambert-Beer law relationship and (ii) new parameterization of leaf area density (LAD) profile. We have supposed that absorption coefficient μ varies with height and depends on LAD distribution. To check validity of the relation proposed, we have compared calculated values with the observations using data sets assimilated during Anglo-Brazilian Amazonian Climate Observation Study experiment at two observational sites located in Reserva Jaru and Reserva Ducke (Brazil) with different types of forest. Among all available measurements, 615 profiles observed between 08 and 18 local mean time for 72 days at 2 locations were selected. For comparison study, two more profiles based on constant- and variable-LAD approximation were introduced. Obtained results indicate that suggested relation: (i) well reproduces PAR profile within the forest in comparison with observations and (ii) shows better agreement with observations in comparison with two other profiles used in this study.

  17. Droplet evaporation on a horizontal substrate under gravity field by mesoscopic modeling.

    PubMed

    Xie, Chiyu; Zhang, Jianying; Bertola, Volfango; Wang, Moran

    2016-02-01

    The evaporation of water drop deposited on a horizontal substrate is investigated using a lattice Boltzmann method (LBM) for multiphase flows with a large-density ratio. To account for the variation of evaporation flux distribution along the drop interface, a novel evaporation scheme is introduced into the LBM framework, and validated by comparison with experimental data. We aim at discovering the effect of gravity on the evaporating drop in detail, and various evaporation conditions are considered as well as different wetting properties of the substrates. An effective diameter is introduced as an indicator of the critical drop size under which gravity is negligible. Our results show that such critical diameter is much smaller than the capillary length, which has been widely accepted as the critical size in previous and current works. The critical diameter is found to be almost independent of the evaporation conditions and the surface wettability. A correlation between this critical diameter and the capillary length is also proposed for easy use in applications. PMID:26562444

  18. An unsteady vortex lattice method model of a horizontal axis wind turbine operating in an upstream rotor wake

    NASA Astrophysics Data System (ADS)

    Hankin, D.; Graham, J. M. R.

    2014-12-01

    An unsteady formulation of the vortex lattice method, VLM, is presented that uses a force- free representation of the wake behind a horizontal axis wind turbine, HAWT, to calculate the aerodynamic loading on a turbine operating in the wake of an upstream rotor. A Cartesian velocity grid is superimposed over the computational domain to facilitate the representation of the atmospheric turbulence surrounding the turbine and wind shear. The wake of an upstream rotor is modelled using two methods: a mean velocity deficit with superimposed turbulence, based on experimental observations, and a purely numeric periodic boundary condition. Both methods are treated as frozen and propagated with the velocity grid. Measurements of the mean thrust and blade root bending moment on a three bladed horizontal axis rotor modelling a 5 MW HAWT at 1:250 scale were carried out in a wind tunnel. Comparisons are made between operation in uniform flow and in the wake of a similarly loaded rotor approximately 6.5 diameters upstream. The measurements were used to validate the output from the VLM simulations, assuming a completely rigid rotor. The trends in the simulation thrust predictions are found to compare well with the uniform flow case, except at low tip speed ratios where there are losses due to stall which are yet to be included in the model. The simple wake model predicts the mean deficit, whilst the periodic boundary condition captures more of the frequency content of the loading in an upstream wake. However, all the thrust loads are over-predicted. The simulation results severely overestimate the bending moment, which needs addressing. However, the reduction in bending due to the simple wake model is found to reflect the experimental data reasonably well.

  19. Comparison of upconing under vertical and horizontal wells in freshwater lenses: sand-box experiments and numerical modeling

    NASA Astrophysics Data System (ADS)

    Stoeckl, Leonard; Stefan, Loeffler; Houben, Georg

    2013-04-01

    Freshwater lenses on islands and in inland areas are often the primary freshwater resource there. The fragile equilibrium between saline and fresh groundwater can be disrupted by excessive pumping, leading to an upward migration of the saline water underneath the well. Sand-box experiments were conducted to compare the upconing at vertical and horizontal wells pumping from a freshwater lens. Results were then compared to numerical simulations. To simulate the cross-section of an "infinite strip island", an acrylic box with a spacing of 5 cm was filled with coarse sand. After saturating the model with degassed saltwater from bottom to top, freshwater recharge was applied from above. By coloring the infiltrating freshwater with different tracer colors using uranine and indigotine we were able to visualize flow paths during pumping. A horizontal and a vertical well were placed at the left and right side of the symmetric island. Both had equal diameter, screen length, depth of placement, and distance to shore. Three increasing pumping rates were applied to each well successively and the electrical conductivity of the abstracted water was continuously measured using a through-flow cell. Results show that no saltwater entered the wells when pumping at the lowest rate. Still, slight saltwater upconing and a shift of the freshwater divide in the island were observed. At the second rate a clear saltwater breakthrough into the vertical well occurred, while the electrical conductivity remained nearly unchanged in the horizontal well. Applying the third (highest) abstraction rate to each of the wells saltwater entered both wells, exceeding drinking water standards in the vertical well. The described behavior indicates the advantage of horizontal over vertical wells on islands and in coastal zones prone to saltwater up-coning. Numerical simulations show similar patterns, even though deviations exist between the second and the third pumping rate, which are under and

  20. Simulation results for a multirate mass transfer modell for immiscible displacement of two fluids in highly heterogeneous porous media

    NASA Astrophysics Data System (ADS)

    Tecklenburg, Jan; Neuweiler, Insa; Dentz, Marco; Carrera, Jesus; Geiger, Sebastian

    2013-04-01

    Flow processes in geotechnical applications do often take place in highly heterogeneous porous media, such as fractured rock. Since, in this type of media, classical modelling approaches are problematic, flow and transport is often modelled using multi-continua approaches. From such approaches, multirate mass transfer models (mrmt) can be derived to describe the flow and transport in the "fast" or mobile zone of the medium. The porous media is then modeled with one mobile zone and multiple immobile zones, where the immobile zones are connected to the mobile zone by single rate mass transfer. We proceed from a mrmt model for immiscible displacement of two fluids, where the Buckley-Leverett equation is expanded by a sink-source-term which is nonlocal in time. This sink-source-term models exchange with an immobile zone with mass transfer driven by capillary diffusion. This nonlinear diffusive mass transfer can be approximated for particular imbibition or drainage cases by a linear process. We present a numerical scheme for this model together with simulation results for a single fracture test case. We solve the mrmt model with the finite volume method and explicit time integration. The sink-source-term is transformed to multiple single rate mass transfer processes, as shown by Carrera et. al. (1998), to make it local in time. With numerical simulations we studied immiscible displacement in a single fracture test case. To do this we calculated the flow parameters using information about the geometry and the integral solution for two phase flow by McWorther and Sunnada (1990). Comparision to the results of the full two dimensional two phase flow model by Flemisch et. al. (2011) show good similarities of the saturation breakthrough curves. Carrera, J., Sanchez-Vila, X., Benet, I., Medina, A., Galarza, G., and Guimera, J.: On matrix diffusion: formulations, solution methods and qualitative effects, Hydrogeology Journal, 6, 178-190, 1998. Flemisch, B., Darcis, M

  1. A Reduced Order Model of Force Displacement Curves for the Failure of Mechanical Bolts in Tension.

    SciTech Connect

    Moore, Keegan J.; Brake, Matthew Robert

    2015-12-01

    Assembled mechanical systems often contain a large number of bolted connections. These bolted connections (joints) are integral aspects of the load path for structural dynamics, and, consequently, are paramount for calculating a structure's stiffness and energy dissipation prop- erties. However, analysts have not found the optimal method to model appropriately these bolted joints. The complexity of the screw geometry causes issues when generating a mesh of the model. This report will explore different approaches to model a screw-substrate connec- tion. Model parameters such as mesh continuity, node alignment, wedge angles, and thread to body element size ratios are examined. The results of this study will give analysts a better understanding of the influences of these parameters and will aide in finding the optimal method to model bolted connections.

  2. A NASTRAN model of a large flexible swing-wing bomber. Volume 2: NASTRAN model development-horizontal stabilzer, vertical stabilizer and nacelle structures

    NASA Technical Reports Server (NTRS)

    Mock, W. D.; Latham, R. A.; Tisher, E. D.

    1982-01-01

    The NASTRAN model plans for the horizontal stabilizer, vertical stabilizer, and nacelle structure were expanded in detail to generate the NASTRAN model for each of these substructures. The grid point coordinates were coded for each element. The material properties and sizing data for each element were specified. Each substructure model was thoroughly checked out for continuity, connectivity, and constraints. These substructures were processed for structural influence coefficients (SIC) point loadings and the deflections were compared to those computed for the aircraft detail models. Finally, a demonstration and validation processing of these substructures was accomplished using the NASTRAN finite element program installed at NASA/DFRC facility.

  3. Evolution of the superposition of displaced number states with the two-atom multiphoton Jaynes Cummings model: interference and entanglement

    NASA Astrophysics Data System (ADS)

    El-Orany, Faisal A. A.

    2006-11-01

    In this paper, we study the evolution of two two-level atoms interacting with a single-mode quantized radiation field, namely, the two-atom multiphoton Jaynes-Cummings model (JCM). We assume that the field and the atoms are initially prepared in the superposition of displaced number states and excited atomic states, respectively. For this system, we investigate the atomic inversion, Wigner function, phase distribution and entanglement. We show that for symmetric (asymmetric) atoms, the system can generate asymmetric (symmetric) cat states at a quarter of the revival time. Furthermore, the degrees of entanglement for the field-atoms and the one-atom-remainder tangles depend on the rate of energy flow between the parties. The interference in phase space decreases the degree of entanglement in the bipartite.

  4. Phase Distribution of the Output of Jaynes-Cummings Model with the Superposition of Squeezed Displaced Fock States

    NASA Astrophysics Data System (ADS)

    Abd Al-Kader, G. M.

    2006-05-01

    The Wigner quasi-probability function for the superposition of squeezed displaced Fock states (SDFS's) is reviewed. The interaction of these states with a two-level atom in cavity with the presence of additional Kerr medium is studied. Exact general matrix elements of the time-dependent operators of a Jaynes-Cummings model (JCM), in the presence of a Kerr medium, with these states are derived. We have obtained the phase distribution by two different ways: one is by Pegg-Barnett formalism, the second is by integration of the Wigner function over the radial variable. Results of these two approaches are compared. The Wigner phase distributions for some values of parameters are illustrated. The behaviors of the distributions have been shown as a function of the squeeze parameter in JCM.

  5. An Evaluation of Sharp Interface Models for CO2 -Brine Displacement in Aquifers.

    PubMed

    Swickrath, Michael J; Mishra, Srikanta; Ravi Ganesh, Priya

    2016-05-01

    Understanding multiphase transport within saline aquifers is necessary for safe and efficient CO2 sequestration. To that end, numerous full-physics codes exist for rigorously modeling multiphase flow within porous and permeable rock formations. High-fidelity simulation with such codes is data- and computation-intensive, and may not be suitable for screening-level calculations. Alternatively, under conditions of vertical equilibrium, a class of sharp-interface models result in simplified relationships that can be solved with limited computing resources and geologic/fluidic data. In this study, the sharp-interface model of Nordbotten and Celia (2006a,2006b) is evaluated against results from a commercial full-physics simulator for a semi-confined system with vertical permeability heterogeneity. In general, significant differences were observed between the simulator and the sharp-interface model results. A variety of adjustments were made to the sharp-interface model including modifications to the fluid saturation and effective viscosity in the two-phase region behind the CO2 -brine interface. These adaptations significantly improved the predictive ability of the sharp interface model while maintaining overall tractability. PMID:26333189

  6. Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection.

    PubMed

    Mayor, T S; Couto, S; Psikuta, A; Rossi, R M

    2015-12-01

    The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s(-1)) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 10(2)-3 × 10(5)). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow

  7. Advanced modelling of the transport phenomena across horizontal clothing microclimates with natural convection

    NASA Astrophysics Data System (ADS)

    Mayor, T. S.; Couto, S.; Psikuta, A.; Rossi, R. M.

    2015-12-01

    The ability of clothing to provide protection against external environments is critical for wearer's safety and thermal comfort. It is a function of several factors, such as external environmental conditions, clothing properties and activity level. These factors determine the characteristics of the different microclimates existing inside the clothing which, ultimately, have a key role in the transport processes occurring across clothing. As an effort to understand the effect of transport phenomena in clothing microclimates on the overall heat transport across clothing structures, a numerical approach was used to study the buoyancy-driven heat transfer across horizontal air layers trapped inside air impermeable clothing. The study included both the internal flow occurring inside the microclimate and the external flow occurring outside the clothing layer, in order to analyze the interdependency of these flows in the way heat is transported to/from the body. Two-dimensional simulations were conducted considering different values of microclimate thickness (8, 25 and 52 mm), external air temperature (10, 20 and 30 °C), external air velocity (0.5, 1 and 3 m s-1) and emissivity of the clothing inner surface (0.05 and 0.95), which implied Rayleigh numbers in the microclimate spanning 4 orders of magnitude (9 × 102-3 × 105). The convective heat transfer coefficients obtained along the clothing were found to strongly depend on the transport phenomena in the microclimate, in particular when natural convection is the most important transport mechanism. In such scenario, convective coefficients were found to vary in wavy-like manner, depending on the position of the flow vortices in the microclimate. These observations clearly differ from data in the literature for the case of air flow over flat-heated surfaces with constant temperature (which shows monotonic variations of the convective heat transfer coefficients, along the length of the surface). The flow patterns and

  8. Sahel decadal rainfall variability and the role of model horizontal resolution

    NASA Astrophysics Data System (ADS)

    Vellinga, Michael; Roberts, Malcolm; Vidale, Pier Luigi; Mizielinski, Matthew S.; Demory, Marie-Estelle; Schiemann, Reinhard; Strachan, Jane; Bain, Caroline

    2016-01-01

    Substantial low-frequency rainfall fluctuations occurred in the Sahel throughout the twentieth century, causing devastating drought. Modeling these low-frequency rainfall fluctuations has remained problematic for climate models for many years. Here we show using a combination of state-of-the-art rainfall observations and high-resolution global climate models that changes in organized heavy rainfall events carry most of the rainfall variability in the Sahel at multiannual to decadal time scales. Ability to produce intense, organized convection allows climate models to correctly simulate the magnitude of late-twentieth century rainfall change, underlining the importance of model resolution. Increasing model resolution allows a better coupling between large-scale circulation changes and regional rainfall processes over the Sahel. These results provide a strong basis for developing more reliable and skilful long-term predictions of rainfall (seasons to years) which could benefit many sectors in the region by allowing early adaptation to impending extremes.

  9. Measuring vulnerability to disaster displacement

    NASA Astrophysics Data System (ADS)

    Brink, Susan A.; Khazai, Bijan; Power, Christopher; Wenzel, Friedemann

    2015-04-01

    aggregate these ideas into a framework of disaster displacement vulnerability that distinguishes between three main aspects of disaster displacement. Disaster displacement can be considered in terms of the number of displaced people and the length of that displacement. However, the literature emphasizes that the severity of disaster displacement can not be measured completely in quantitative terms. Thus, we include a measure representing people who are trapped and unable to leave their homes due to mobility, resources or for other reasons. Finally the third main aspect considers the difficulties that are associated with displacement and reflects the difference between the experiences of those who are displaced into safe and supportive environments as compared to those whose only alternate shelter is dangerous and inadequate for their needs. Finally, we apply the framework to demonstrate a methodology to estimate vulnerability to disaster displacement. Using data from the Global Earthquake Model (GEM) Social and Economic Vulnerability sub-National Database, we generate an index to measure the vulnerability of Japanese prefectures to the dimensions of displacement included in the framework. References Yonitani, M. (2014). Global Estimates 2014: People displaced by disasters. http://www.internal-displacement.org/publications/2014/global-estimates-2014-people-displaced-by-disasters/

  10. The effect of horizontal resolution on simulation quality in the Community Atmospheric Model, CAM5.1

    DOE PAGESBeta

    Wehner, Michael F.; Reed, Kevin A.; Li, Fuyu; Prabhat, -; Bacmeister, Julio; Chen, Cheng -Ta; Paciorek, Christopher; Gleckler, Peter J.; Sperber, Kenneth R.; Collins, William D.; et al

    2014-11-05

    We present an analysis of version 5.1 of the Community Atmospheric Model (CAM5.1) at a high horizontal resolution. Intercomparison of this global model at approximately 0.25°, 1°, and 2° is presented for extreme daily precipitation as well as for a suite of seasonal mean fields. In general, extreme precipitation amounts are larger in high resolution than in lower-resolution configurations. In many but not all locations and/or seasons, extreme daily precipitation rates in the high-resolution configuration are higher and more realistic. The high-resolution configuration produces tropical cyclones up to category 5 on the Saffir-Simpson scale and a comparison to observations revealsmore » both realistic and unrealistic model behavior. In the absence of extensive model tuning at high resolution, simulation of many of the mean fields analyzed in this study is degraded compared to the tuned lower-resolution public released version of the model.« less

  11. Analysis of the Complex Fracture Flow in Multiple Fractured Horizontal Wells with the Fractal Tree-Like Network Models

    NASA Astrophysics Data System (ADS)

    Wang, Wendong; Su, Yuliang; Zhang, Xiao; Sheng, Guanglong; Ren, Long

    2015-03-01

    This paper formulates a fractal-tree network model to address the challenging problem of characterizing the hydraulic fracture network in unconventional reservoirs. It has been proved that the seepage flow in tight/shale oil reservoirs is much more complicated to the conventional formation. To further understand the flow mechanisms in such a complex system, a semi-analytical model considering "branch network fractures" was established stage by stage using point source method and superposition principle. Fractal method was employed to generate and represent induced fracture network around bi-wing fractures. In addition, based on the new established model and solution, deterministic fractal-tree-like fracture network patterns and heterogeneity were carefully investigated and compared with the simulation model. Results show that the fractal dimension for the fracture network has significant effect on the connectivity of the stimulated reservoir. The proposed fractal model may capture the characteristics of the heterogeneous complex fracture network and help in understanding the flow and transport mechanisms of multiple fractured horizontal wells.

  12. Capillary filling rules and displacement mechanisms for spontaneous imbibition of CO2 for carbon storage and EOR using micro-model experiments and pore scale simulation

    NASA Astrophysics Data System (ADS)

    Chapman, E.; Yang, J.; Crawshaw, J.; Boek, E. S.

    2012-04-01

    In the 1980s, Lenormand et al. carried out their pioneering work on displacement mechanisms of fluids in etched networks [1]. Here we further examine displacement mechanisms in relation to capillary filling rules for spontaneous imbibition. Understanding the role of spontaneous imbibition in fluid displacement is essential for refining pore network models. Generally, pore network models use simple capillary filling rules and here we examine the validity of these rules for spontaneous imbibition. Improvement of pore network models is vital for the process of 'up-scaling' to the field scale for both enhanced oil recovery (EOR) and carbon sequestration. In this work, we present our experimental microfluidic research into the displacement of both supercritical CO2/deionised water (DI) systems and analogous n-decane/air - where supercritical CO2 and n-decane are the respective wetting fluids - controlled by imbibition at the pore scale. We conducted our experiments in etched PMMA and silicon/glass micro-fluidic hydrophobic chips. We first investigate displacement in single etched pore junctions, followed by displacement in complex network designs representing actual rock thin sections, i.e. Berea sandstone and Sucrosic dolomite. The n-decane/air experiments were conducted under ambient conditions, whereas the supercritical CO2/DI water experiments were conducted under high temperature and pressure in order to replicate reservoir conditions. Fluid displacement in all experiments was captured via a high speed video microscope. The direction and type of displacement the imbibing fluid takes when it enters a junction is dependent on the number of possible channels in which the wetting fluid can imbibe, i.e. I1, I2 and I3 [1]. Depending on the experiment conducted, the micro-models were initially filled with either DI water or air before the wetting fluid was injected. We found that the imbibition of the wetting fluid through a single pore is primarily controlled by the

  13. Crack growth rate in core shroud horizontal welds using two models for a BWR

    NASA Astrophysics Data System (ADS)

    Arganis Juárez, C. R.; Hernández Callejas, R.; Medina Almazán, A. L.

    2015-05-01

    An empirical crack growth rate correlation model and a predictive model based on the slip-oxidation mechanism for Stress Corrosion Cracking (SCC) were used to calculate the crack growth rate in a BWR core shroud. In this study, the crack growth rate was calculated by accounting for the environmental factors related to aqueous environment, neutron irradiation to high fluence and the complex residual stress conditions resulting from welding. In estimating the SCC behavior the crack growth measurements data from a Boiling Water Reactor (BWR) plant are referred to, and the stress intensity factor vs crack depth throughout thickness is calculated using a generic weld residual stress distribution for a core shroud, with a 30% stress relaxation induced by neutron irradiation. Quantitative agreement is shown between the measurements of SCC growth rate and the predictions of the slip-oxidation mechanism model for relatively low fluences (5 × 1024 n/m2), and the empirical model predicted better the SCC growth rate than the slip-oxidation model for high fluences (>1 × 1025 n/m2). The relevance of the models predictions for SCC growth rate behavior depends on knowing the model parameters.

  14. Modeling and Performance Improvement of the Constant Power Regulator Systems in Variable Displacement Axial Piston Pump

    PubMed Central

    Park, Sung Hwan; Lee, Ji Min; Kim, Jong Shik

    2013-01-01

    An irregular performance of a mechanical-type constant power regulator is considered. In order to find the cause of an irregular discharge flow at the cut-off pressure area, modeling and numerical simulations are performed to observe dynamic behavior of internal parts of the constant power regulator system for a swashplate-type axial piston pump. The commercial numerical simulation software AMESim is applied to model the mechanical-type regulator with hydraulic pump and simulate the performance of it. The validity of the simulation model of the constant power regulator system is verified by comparing simulation results with experiments. In order to find the cause of the irregular performance of the mechanical-type constant power regulator system, the behavior of main components such as the spool, sleeve, and counterbalance piston is investigated using computer simulation. The shape modification of the counterbalance piston is proposed to improve the undesirable performance of the mechanical-type constant power regulator. The performance improvement is verified by computer simulation using AMESim software. PMID:24282389

  15. Lunar highland crustal models based on iron concentrations - Isostasy and center-of-mass displacement

    NASA Technical Reports Server (NTRS)

    Haines, E. L.; Metzger, A. E.

    1980-01-01

    Data is introduced on the iron concentrations of the lunar surface which have been refined by means of convolution corrections to restore the spatial resolution and contrast lost by the omnidirectional spectrometer. This refined iron data is synthesized with other orbital seismic, and lunar sample data to derive highland crustal density and thickness, and isostasy and lunar centers of mass models are examined in light of this new information. A model is developed by which highland crustal density is calculated for each highland region from orbital observations of Fe, Mg and Ti concentrations. The results of this model are presented numerically and graphically for 35 highland and two non-highland regions. Density and thickness results are then applied to two long-standing lunar problems: (1) the nature of highland isostasy, which is shown to be controlled by crustal thickness rather than density, and (2) the separation of the moon's mass and figure centers, which is shown to be due to the crustal thickness difference between the lunar near and far sides.

  16. How does increasing horizontal resolution in a global climate model improve the simulation of aerosol-cloud interactions?

    SciTech Connect

    Ma, Po -Lun; Rasch, Philip J.; Wang, Minghuai; Wang, Hailong; Ghan, Steven J.; Easter, Richard C.; Gustafson, Jr., William I.; Liu, Xiaohong; Zhang, Yuying; Ma, Hsi -Yen

    2015-06-28

    The Community Atmosphere Model Version 5 is run at horizontal grid spacing of 2, 1, 0.5, and 0.25 degrees, with the meteorology nudged towards the Year Of Tropical Convection analysis, and cloud simulators and the collocated A-Train satellite observations are used to explore the resolution dependence of aerosol-cloud interactions. The higher-resolution model produces results that agree better with observations, showing an increase of susceptibility of cloud droplet size, indicating a stronger first aerosol indirect forcing (AIF), and a decrease of susceptibility of precipitation probability, suggesting a weaker second AIF. The resolution sensitivities of AIF are attributed to those of droplet nucleation and precipitation parameterizations. The annual average AIF in the northern hemisphere mid-latitudes (where most anthropogenic emissions occur) in the 0.25° model is reduced by about 1 W m⁻² (-30%) compared to the 2° model, leading to a 0.26 W m⁻² reduction (-15%) in the global annual average AIF.

  17. Modeling distance-dependent individual head-related transfer functions in the horizontal plane using frontal projection headphones.

    PubMed

    Sunder, Kaushik; Gan, Woon-Seng; Tan, Ee-Leng

    2015-07-01

    The veracity of virtual audio is degraded by the use of non-individualized head-related transfer functions (HRTFs) due to the introduction of front-back, elevation confusions, and timbral coloration. Hence, an accurate reproduction of spatial sound demands the use of individualized HRTFs. Measuring distance-dependent individualized HRTFs can be extremely tedious, since it requires precise measurements at several distances in the proximal region (<1 m) for each individual. This paper proposes a technique to model distance-dependent individualized HRTFs in the horizontal plane using "frontal projection headphones playback" that does not require individualized measurements. The frontal projection headphones [Sunder, Tan, and Gan (2013). J. Audio Eng. Soc. 61, 989-1000] project the sound directly onto the pinnae from the front, and thus inherently create listener's idiosyncratic pinna cues at the eardrum. Perceptual experiments were conducted to investigate cues (auditory parallax and interaural level differences) that aid distance perception in anechoic conditions. Interaural level differences were identified as the prominent cue for distance perception and a spherical head model was used to model these distance-dependent features. Detailed psychophysical experiments revealed that the modeled distance-dependent individualized HRTFs exhibited localization performance close to the measured distance-dependent individualized HRTFs for all subjects. PMID:26233016

  18. Unsteady Hybrid Navier-Stokes/Vortex Model for Numerical Study of Horizontal Axis Wind Turbine Aerodynamics under Yaw Conditions

    NASA Astrophysics Data System (ADS)

    Suzuki, Kensuke

    A new analysis tool, an unsteady Hybrid Navier-Stokes/Vortex Model, for a horizontal axis wind turbine (HAWT) in yawed flow is presented, and its convergence and low cost computational performance are demonstrated. In earlier work, a steady Hybrid Navier-Stokes/Vortex Model was developed with a view to improving simulation results obtained by participants of the NASA Ames blind comparison workshop, following the NREL Unsteady Aerodynamics Experiment. The hybrid method was shown to better predict rotor torque and power over the range of wind speeds, from fully attached to separated flows. A decade has passed since the workshop was held and three dimensional unsteady Navier-Stokes analyses have become available using super computers. In the first chapter, recent results of unsteady Euler and Navier-Stokes computations are reviewed as standard references of what is currently possible and are contrasted with results of the Hybrid Navier-Stokes/Vortex Model in steady flow. In Chapter 2, the computational method for the unsteady Hybrid model is detailed. The grid generation procedure, using ICEM CFD, is presented in Chapter 3. Steady and unsteady analysis results for the NREL Phase IV rotor and for a modified "swept NREL rotor" are presented in Chapter 4-Chapter 7.

  19. Caffeine-induced Ca2+ oscillations in type I horizontal cell of carp retina: A mathematical model

    PubMed Central

    Lv, Ting; Zhang, Pu-Ming; Gong, Hai-Qing; Liang, Pei-Ji

    2014-01-01

    Oscillations in intracellular free Ca2+ concentration ([Ca2+]i) have been observed in a variety of cell types. In the present study, we constructed a mathematical model to simulate the caffeine-induced [Ca2+]i oscillations based on experimental data obtained from isolated type I horizontal cell of carp retina. The results of model analysis confirm the notion that the caffeine-induced [Ca2+]i oscillations involve a number of cytoplasmic and endoplasmic Ca2+ processes that interact with each other. Using this model, we evaluated the importance of store-operated channel (SOC) in caffeine-induced [Ca2+]i oscillations. The model suggests that store-operated Ca2+ entry (SOCE) is elicited upon depletion of the endoplasmic reticulum (ER). When the SOC conductance is set to 0, caffeine-induced [Ca2+]i oscillations are abolished, which agrees with the experimental observation that [Ca2+]i oscillations were abolished when SOC was blocked pharmacologically, verifying that SOC is necessary for sustained [Ca2+]i oscillations. PMID:25483284

  20. Modeling total phosphorus removal in an aquatic environment restoring horizontal subsurface flow constructed wetland based on artificial neural networks.

    PubMed

    Li, Wei; Zhang, Yan; Cui, Lijuan; Zhang, Manyin; Wang, Yifei

    2015-08-01

    A horizontal subsurface flow constructed wetland (HSSF-CW) was designed to improve the water quality of an artificial lake in Beijing Wildlife Rescue and Rehabilitation Center, Beijing, China. Artificial neural networks (ANNs), including multilayer perceptron (MLP) and radial basis function (RBF), were used to model the removal of total phosphorus (TP). Four variables were selected as the input parameters based on the principal component analysis: the influent TP concentration, water temperature, flow rate, and porosity. In order to improve model accuracy, alternative ANNs were developed by incorporating meteorological variables, including precipitation, air humidity, evapotranspiration, solar heat flux, and barometric pressure. A genetic algorithm and cross-validation were used to find the optimal network architectures for the ANNs. Comparison of the observed data and the model predictions indicated that, with careful variable selection, ANNs appeared to be an efficient and robust tool for predicting TP removal in the HSSF-CW. Comparison of the accuracy and efficiency of MLP and RBF for predicting TP removal showed that the RBF with additional meteorological variables produced the most accurate results, indicating a high potentiality for modeling TP removal in the HSSF-CW. PMID:25903184

  1. Lateral displacement and rotational displacement sensor

    DOEpatents

    Duden, Thomas

    2014-04-22

    A position measuring sensor formed from opposing sets of capacitor plates measures both rotational displacement and lateral displacement from the changes in capacitances as overlapping areas of capacitors change. Capacitances are measured by a measuring circuit. The measured capacitances are provided to a calculating circuit that performs calculations to obtain angular and lateral displacement from the capacitances measured by the measuring circuit.

  2. The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

    NASA Astrophysics Data System (ADS)

    van Wessem, J. M.; Ligtenberg, S. R. M.; Reijmer, C. H.; van de Berg, W. J.; van den Broeke, M. R.; Barrand, N. E.; Thomas, E. R.; Turner, J.; Wuite, J.; Scambos, T. A.; van Meijgaard, E.

    2016-02-01

    This study presents a high-resolution (˜ 5.5 km) estimate of surface mass balance (SMB) over the period 1979-2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a firn densification model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in situ SMB observations and discharge rates from six glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes, complicating a full model evaluation. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr-1 in the western AP (WAP) and below 500 mm we yr-1 in the eastern AP (EAP), not resolved by coarser data sets such as ERA-Interim. The average AP ice-sheet-integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr-1 with an interannual variability of 58 Gt yr-1, which is dominated by precipitation (PR) (365 ± 57 Gt yr-1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr-1), where PR is large (276 ± 47 Gt yr-1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr-1) and PR (84 ± 11 Gt yr-1). Total sublimation is 11 ± 2 Gt yr-1 and meltwater runoff into the ocean is 4 ± 4 Gt yr-1. There are no significant trends in any of the modelled AP SMB components, except for snowmelt that shows a significant decrease over the last 36 years (-0.36 Gt yr-2).

  3. New flow boiling heat transfer model for hydrocarbons evaporating inside horizontal tubes

    SciTech Connect

    Chen, G. F.; Gong, M. Q.; Wu, J. F.; Zou, X.; Wang, S.

    2014-01-29

    Hydrocarbons have high thermodynamic performances, belong to the group of natural refrigerants, and they are the main components in mixture Joule-Thomson low temperature refrigerators (MJTR). New evaluations of nucleate boiling contribution and nucleate boiling suppression factor in flow boiling heat transfer have been proposed for hydrocarbons. A forced convection heat transfer enhancement factor correlation incorporating liquid velocity has also been proposed. In addition, the comparisons of the new model and other classic models were made to evaluate its accuracy in heat transfer prediction.

  4. Texaco sets horizontal well marks

    SciTech Connect

    Not Available

    1992-07-06

    This paper reports that Texaco Exploration and Production Inc. has completed the first dual lateral horizontal well in East Texas and claimed a horizontal oil well record in the Gulf of Mexico. The East Texas well, 1 Texaco Fee Brookeland, is the company's first dual lateral well. Site is in Newton County. The Brookeland well was drilled vertically to the top of Cretaceous Austin chalk at 9,138 ft. Texaco set casing, then drilled horizontally 3,242 ft to the southeast and 3,000 ft to the northwest for a total horizontal displacement of 6,242 ft. Texaco set an industry record offshore with its B19-ST well on its Teal prospect in Eugene Island Block 338, its first horizontal oil well in the gulf, by drilling a horizontal section of 1,414 ft. Measured depth (MD) is 7,500 ft and true vertical depth (TVD) 4,662 ft. Site is in 268 ft of water. Drilling horizontally through the Pleistocene prograding sand complex allowed Texaco to penetrate 50% more of the reservoir than would have been possible with a conventional well, Wallace the. In another industry first, Texaco isolated the Teal reservoir gas cap by setting intermediate casing 50 ft below the oil-gas contact with the 90{degrees} angle already established because of concern that the reservoir had an expanded gas cap. The dual lateral Brookeland well cost $500,000-700,000 less than two vertical wells capable of comparable production rates and recovery. Texaco expects the full cost of the well, production facilities, and gathering system to pay out in about 4 months. Texaco estimates the B19-ST well cost about 10% more than a Teal vertical well. A cross discipline team of Texaco geologists, geophysicists, engineers, and field technicians contributed to the success of both projects.

  5. The photoelectric displacement converter

    NASA Astrophysics Data System (ADS)

    Dragoner, Valeriu V.

    2005-02-01

    In the article are examined questions of constructing photoelectric displacement converter satisfying demands that are stated above. Converter has channels of approximate and precise readings. The approximate reading may be accomplished either by the method of reading from a code mask or by the method of the consecutive calculation of optical scale gaps number. Phase interpolator of mouar strips" gaps is determined as a precise measuring. It is shown mathematical model of converter that allow evaluating errors and operating speed of conversion.

  6. Application of a three-dimensional model for a study of the energy transfer of a high-pressure mercury horizontal lamp

    SciTech Connect

    Ben Hamida, M. B.; Charrada, K.

    2012-06-15

    This paper is devoted to study the dynamics of a discharge lamp with high intensity in a horizontal position. As an example of application, we chose the high-pressure mercury lamp. For this, we realized a three-dimensional model, a stable and powered DC. After the validation of this model, we used it to reproduce the influence of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp operating in a horizontal position. Indeed, the mass of mercury and the electric current are modified and the effect of convective transport is studied.

  7. The effect of small-scale vertical mixing of horizontal momentum in a general circulation model

    NASA Technical Reports Server (NTRS)

    Stone, P. H.; Somerville, R. C. J.; Quirk, W. J.

    1974-01-01

    Several experiments are described in which the sub-grid-scale vertical eddy viscosity in the GISS global general circulation model was varied. The results show that large viscosities suppress large-scale eddies in middle and high latitudes, but enhance the circulation in the tropical Hadley cell and increase the extent of the tropical easterlies. Comparison with observations shows that the GISS model requires eddy viscosities about 1 sq m per sec or less to give realistic results for middle and high latitudes, and eddy viscosities about 100 sq m per sec to give realistic results for low latitudes. A plausible mechanism for the implied increase in small-scale mixing in low latitudes is cumulus convection.

  8. Direct pore-to-core up-scaling of displacement processes: Dynamic pore network modeling and experimentation

    NASA Astrophysics Data System (ADS)

    Aghaei, Arash; Piri, Mohammad

    2015-03-01

    We present a new dynamic pore network model that is capable of up-scaling two-phase flow processes from pore to core. This dynamic model provides a platform to study various flow processes in porous media at the core scale using the pore-scale physics. The most critical features of this platform include (1) the incorporation of viscous, capillary, and gravity pressure drops in pore-scale displacement thresholds, (2) wetting-phase corner flow in capillary elements with angular cross-sections, (3) adjustments of corner interfaces between wetting and non-wetting phases based on changes in local capillary pressure, (4) simultaneous injection of wetting and non-wetting phases from the inlet of the medium at constant flow rates that makes the study of steady-state processes possible, (5) heavy parallelization using a three-dimensional domain decomposition scheme that enables the study of two-phase flow at the core scale, and (6) constant pressure boundary condition at the outlet. For the validation of the dynamic model, three two-phase miniature core-flooding experiments were performed in a state-of-the-art micro core-flooding system integrated with a high-resolution X-ray micro-CT scanner. The dynamic model was rigorously validated by comparing the predicted local saturation profiles, fractional flow curves, relative permeabilities, and residual oil saturations against their experimental counterparts. The validated dynamic model was then used to study low-IFT and high-viscosity two-phase flow processes and investigate the effect of high capillary number on relative permeabilities and residual oil saturation.

  9. The modelled surface mass balance of the Antarctic Peninsula at 5.5 km horizontal resolution

    NASA Astrophysics Data System (ADS)

    van Wessem, J. M.; Ligtenberg, S. R. M.; Reijmer, C. H.; van de Berg, W. J.; van den Broeke, M. R.; Barrand, N. E.; Thomas, E. R.; Turner, J.; Wuite, J.; Scambos, T. A.; van Meijgaard, E.

    2015-09-01

    This study presents a high-resolution (~ 5.5 km) estimate of Surface Mass Balance (SMB) over the period 1979-2014 for the Antarctic Peninsula (AP), generated by the regional atmospheric climate model RACMO2.3 and a Firn Densification Model (FDM). RACMO2.3 is used to force the FDM, which calculates processes in the snowpack, such as meltwater percolation, refreezing and runoff. We evaluate model output with 132 in-situ SMB observations and discharge rates from 6 glacier drainage basins, and find that the model realistically simulates the strong spatial variability in precipitation, but that significant biases remain as a result of the highly complex topography of the AP. It is also clear that the observations significantly underrepresent the high-accumulation regimes. The SMB map reveals large accumulation gradients, with precipitation values above 3000 mm we yr-1 over the western AP (WAP) and below 500 mm we yr-1 on the eastern AP (EAP), not resolved by coarser data-sets such as ERA-Interim. The other SMB components are one order of magnitude smaller, with drifting snow sublimation the largest ablation term removing up to 100 mm we yr-1 of mass. Snowmelt is widespread over the AP, reaching 500 mm we yr-1 towards the northern ice shelves, but the meltwater mostly refreezes. As a result runoff fluxes are low, but still considerable (200 mm we yr-1) over the Larsen (B/C), Wilkins and George VI ice shelves. The average AP ice sheet integrated SMB, including ice shelves (an area of 4.1 × 105 km2), is estimated at 351 Gt yr-1 with an interannual variability of 58 Gt yr-1, which is dominated by precipitation (PR) (365 ± 57 Gt yr-1). The WAP (2.4 × 105 km2) SMB (276 ± 47 Gt yr-1), where PR is large (276 ± 47 Gt yr-1), dominates over the EAP (1.7 × 105 km2) SMB (75 ± 11 Gt yr-1) and PR (84 ± 11 Gt yr-1). Total sublimation is 11 ± 2 Gt yr-1 and meltwater runoff into the ocean is 4 ± 4 Gt yr-1. There are no significant trends in any of the AP SMB components, except

  10. A Generic 1D Forward Modeling and Inversion Algorithm for TEM Sounding with an Arbitrary Horizontal Loop

    NASA Astrophysics Data System (ADS)

    Li, Zhanhui; Huang, Qinghua; Xie, Xingbing; Tang, Xingong; Chang, Liao

    2016-08-01

    We present a generic 1D forward modeling and inversion algorithm for transient electromagnetic (TEM) data with an arbitrary horizontal transmitting loop and receivers at any depth in a layered earth. Both the Hankel and sine transforms required in the forward algorithm are calculated using the filter method. The adjoint-equation method is used to derive the formulation of data sensitivity at any depth in non-permeable media. The inversion algorithm based on this forward modeling algorithm and sensitivity formulation is developed using the Gauss-Newton iteration method combined with the Tikhonov regularization. We propose a new data-weighting method to minimize the initial model dependence that enhances the convergence stability. On a laptop with a CPU of i7-5700HQ@3.5 GHz, the inversion iteration of a 200 layered input model with a single receiver takes only 0.34 s, while it increases to only 0.53 s for the data from four receivers at a same depth. For the case of four receivers at different depths, the inversion iteration runtime increases to 1.3 s. Modeling the data with an irregular loop and an equal-area square loop indicates that the effect of the loop geometry is significant at early times and vanishes gradually along the diffusion of TEM field. For a stratified earth, inversion of data from more than one receiver is useful in noise reducing to get a more credible layered earth. However, for a resistive layer shielded below a conductive layer, increasing the number of receivers on the ground does not have significant improvement in recovering the resistive layer. Even with a down-hole TEM sounding, the shielded resistive layer cannot be recovered if all receivers are above the shielded resistive layer. However, our modeling demonstrates remarkable improvement in detecting the resistive layer with receivers in or under this layer.

  11. A Generic 1D Forward Modeling and Inversion Algorithm for TEM Sounding with an Arbitrary Horizontal Loop

    NASA Astrophysics Data System (ADS)

    Li, Zhanhui; Huang, Qinghua; Xie, Xingbing; Tang, Xingong; Chang, Liao

    2016-07-01

    We present a generic 1D forward modeling and inversion algorithm for transient electromagnetic (TEM) data with an arbitrary horizontal transmitting loop and receivers at any depth in a layered earth. Both the Hankel and sine transforms required in the forward algorithm are calculated using the filter method. The adjoint-equation method is used to derive the formulation of data sensitivity at any depth in non-permeable media. The inversion algorithm based on this forward modeling algorithm and sensitivity formulation is developed using the Gauss-Newton iteration method combined with the Tikhonov regularization. We propose a new data-weighting method to minimize the initial model dependence that enhances the convergence stability. On a laptop with a CPU of i7-5700HQ@3.5 GHz, the inversion iteration of a 200 layered input model with a single receiver takes only 0.34 s, while it increases to only 0.53 s for the data from four receivers at a same depth. For the case of four receivers at different depths, the inversion iteration runtime increases to 1.3 s. Modeling the data with an irregular loop and an equal-area square loop indicates that the effect of the loop geometry is significant at early times and vanishes gradually along the diffusion of TEM field. For a stratified earth, inversion of data from more than one receiver is useful in noise reducing to get a more credible layered earth. However, for a resistive layer shielded below a conductive layer, increasing the number of receivers on the ground does not have significant improvement in recovering the resistive layer. Even with a down-hole TEM sounding, the shielded resistive layer cannot be recovered if all receivers are above the shielded resistive layer. However, our modeling demonstrates remarkable improvement in detecting the resistive layer with receivers in or under this layer.

  12. Model for simulation of turbulence at a point rotating as on a horizontal-axis wind turbine or a vertical-axis wind turbine blade

    SciTech Connect

    Powell, D.C.; Connell, J.R.

    1985-11-01

    Previous theoretical work has examined turbulence at a point rotating in a vertical plane, as in a horizontal-axis wind turbine (HAWT). The present paper extends the theoretical model to apply to the vertical-axis wind turbine (VAWT). The model's results, as simulated by computer, are compared with corresponding results obtained by analyzing field data, confirming the model's usefulness. Finally, suggestions are made for future applications of the model.

  13. Three-dimensional modelling of horizontal chemical vapor deposition. I - MOCVD at atmospheric pressure

    NASA Technical Reports Server (NTRS)

    Ouazzani, Jalil; Rosenberger, Franz

    1990-01-01

    A systematic numerical study of the MOCVD of GaAs from trimethylgallium and arsine in hydrogen or nitrogen carrier gas at atmospheric pressure is reported. Three-dimensional effects are explored for CVD reactors with large and small cross-sectional aspect ratios, and the effects on growth rate uniformity of tilting the susceptor are investigated for various input flow rates. It is found that, for light carrier gases, thermal diffusion must be included in the model. Buoyancy-driven three-dimensional flow effects can greatly influence the growth rate distribution through the reactor. The importance of the proper design of the lateral thermal boundary conditions for obtaining layers of uniform thickness is emphasized.

  14. Stable, accurate and efficient computation of normal modes for horizontal stratified models

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Chen, Xiaofei

    2016-08-01

    We propose an adaptive root-determining strategy that is very useful when dealing with trapped modes or Stoneley modes whose energies become very insignificant on the free surface in the presence of low-velocity layers or fluid layers in the model. Loss of modes in these cases or inaccuracy in the calculation of these modes may then be easily avoided. Built upon the generalized reflection/transmission coefficients, the concept of `family of secular functions' that we herein call `adaptive mode observers' is thus naturally introduced to implement this strategy, the underlying idea of which has been distinctly noted for the first time and may be generalized to other applications such as free oscillations or applied to other methods in use when these cases are encountered. Additionally, we have made further improvements upon the generalized reflection/transmission coefficient method; mode observers associated with only the free surface and low-velocity layers (and the fluid/solid interface if the model contains fluid layers) are adequate to guarantee no loss and high precision at the same time of any physically existent modes without excessive calculations. Finally, the conventional definition of the fundamental mode is reconsidered, which is entailed in the cases under study. Some computational aspects are remarked on. With the additional help afforded by our superior root-searching scheme and the possibility of speeding calculation using a less number of layers aided by the concept of `turning point', our algorithm is remarkably efficient as well as stable and accurate and can be used as a powerful tool for widely related applications.

  15. Stable, accurate and efficient computation of normal modes for horizontal stratified models

    NASA Astrophysics Data System (ADS)

    Wu, Bo; Chen, Xiaofei

    2016-06-01

    We propose an adaptive root-determining strategy that is very useful when dealing with trapped modes or Stoneley modes whose energies become very insignificant on the free surface in the presence of low-velocity layers or fluid layers in the model. Loss of modes in these cases or inaccuracy in the calculation of these modes may then be easily avoided. Built upon the generalized reflection/transmission coefficients, the concept of "family of secular functions" that we herein call "adaptive mode observers", is thus naturally introduced to implement this strategy, the underlying idea of which has been distinctly noted for the first time and may be generalized to other applications such as free oscillations or applied to other methods in use when these cases are encountered. Additionally, we have made further improvements upon the generalized reflection/transmission coefficient method; mode observers associated with only the free surface and low-velocity layers (and the fluid/solid interface if the model contains fluid layers) are adequate to guarantee no loss and high precision at the same time of any physically existent modes without excessive calculations. Finally, the conventional definition of the fundamental mode is reconsidered, which is entailed in the cases under study. Some computational aspects are remarked on. With the additional help afforded by our superior root-searching scheme and the possibility of speeding calculation using a less number of layers aided by the concept of "turning point", our algorithm is remarkably efficient as well as stable and accurate and can be used as a powerful tool for widely related applications.

  16. Modeling the indirect effect of Wolbachia on the infection dynamics of horizontally transmitted viruses.

    PubMed

    Strauß, Jakob F; Telschow, Arndt

    2015-01-01

    Intracellular bacteria of the genus Wolbachia are widely distributed in arthropods. There is growing empirical evidence that Wolbachia directly interacts with viruses and other parasites inside the arthropod host, sometimes resulting in low or no pathogen replication. Previous theoretical studies showed that this direct effect of Wolbachia can result in a reduced virus prevalence (within the population), suggesting that Wolbachia could be used in the biological control of vector-borne diseases (e.g., dengue fever). However, Wolbachia might also indirectly affect virus dynamics because Wolbachia-induced reproductive phenotypes (cytoplasmic incompatibility or male killing) increase the larval mortality of hosts and thus alter the age structure of populations. We investigated this indirect effect using mathematical models with overlapping generations, and found the results to depend strongly on the host's life history. In general, the indirect effect can result in two different outcomes: (1) reduced virus prevalence and virus invasion ability, and (2) increased virus prevalence and virus invasion ability. The former occurs for host species with larval competition and undercompensation, the latter for hosts with either adult competition or larval competition and overcompensation. These findings suggest that the effect of Wolbachia on a specific virus is sensitive to the host's life history. We discuss the results with respect to biocontrol programs using Wolbachia. PMID:25972858

  17. Modeling and Validation of Performance Limitations for the Optimal Design of Interferometric and Intensity-Modulated Fiber Optic Displacement Sensors

    SciTech Connect

    Moro, Erik A.

    2012-06-07

    Optical fiber sensors offer advantages over traditional electromechanical sensors, making them particularly well-suited for certain measurement applications. Generally speaking, optical fiber sensors respond to a desired measurand through modulation of an optical signal's intensity, phase, or wavelength. Practically, non-contacting fiber optic displacement sensors are limited to intensity-modulated and interferometric (or phase-modulated) methodologies. Intensity-modulated fiber optic displacement sensors relate target displacement to a power measurement. The simplest intensity-modulated sensor architectures are not robust to environmental and hardware fluctuations, since such variability may cause changes in the measured power level that falsely indicate target displacement. Differential intensity-modulated sensors have been implemented, offering robustness to such intensity fluctuations, and the speed of these sensors is limited only by the combined speed of the photodetection hardware and the data acquisition system (kHz-MHz). The primary disadvantages of intensity-modulated sensing are the relatively low accuracy (?m-mm for low-power sensors) and the lack of robustness, which consequently must be designed, often with great difficulty, into the sensor's architecture. White light interferometric displacement sensors, on the other hand, offer increased accuracy and robustness. Unlike their monochromatic-interferometer counterparts, white light interferometric sensors offer absolute, unambiguous displacement measurements over large displacement ranges (cm for low-power, 5 mW, sources), necessitating no initial calibration, and requiring no environmental or feedback control. The primary disadvantage of white light interferometric displacement sensors is that their utility in dynamic testing scenarios is limited, both by hardware bandwidth and by their inherent high-sensitivity to Doppler-effects. The decision of whether to use either an intensity

  18. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    SciTech Connect

    Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

    2015-06-03

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.

  19. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Osetsky, Y. N.; Stoller, R. E.

    2015-10-01

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascade production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (∼0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential. The Gao-Weber potential appears to give a more realistic description of cascade dynamics in SiC, but still has some shortcomings when the defect migration barriers are compared to the ab initio results.

  20. Molecular dynamics modeling of atomic displacement cascades in 3C-SiC: Comparison of interatomic potentials

    DOE PAGESBeta

    Samolyuk, German D.; Osetskiy, Yury N.; Stoller, Roger E.

    2015-06-03

    We used molecular dynamics modeling of atomic displacement cascades to characterize the nature of primary radiation damage in 3C-SiC. We demonstrated that the most commonly used interatomic potentials are inconsistent with ab initio calculations of defect energetics. Both the Tersoff potential used in this work and a modified embedded-atom method potential reveal a barrier to recombination of the carbon interstitial and carbon vacancy which is much higher than the density functional theory (DFT) results. The barrier obtained with a newer potential by Gao and Weber is closer to the DFT result. This difference results in significant differences in the cascademore » production of point defects. We have completed both 10 keV and 50 keV cascade simulations in 3C-SiC at a range of temperatures. In contrast to the Tersoff potential, the Gao-Weber potential produces almost twice as many C vacancies and interstitials at the time of maximum disorder (~0.2 ps) but only about 25% more stable defects at the end of the simulation. Only about 20% of the carbon defects produced with the Tersoff potential recombine during the in-cascade annealing phase, while about 60% recombine with the Gao-Weber potential.« less

  1. The Chrysler-Weldtech Approach to Retraining Displaced Workers. A Model Project to Develop Specialized Welding Skills Required for Modern Auto Assembly Operations. Final Technical Report.

    ERIC Educational Resources Information Center

    Lyons, Thomas M.; Knight, Glen A.

    A model project was conducted to demonstrate how Chrysler, in partnership with the education community and the government, could provide technical training to enable displaced workers to contribute to the "H-Body" car launch, to improve their job skills, and to enhance their future employability. The training was conducted on a pilot basis for 2…

  2. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... NEW STATIONARY SOURCES Standards of Performance for Stationary Compression Ignition Internal Combustion Engines Part 60, Subpt. IIII, Table 1 Table 1 to Subpart IIII of Part 60—Emission Standards for...-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection...

  3. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... NEW STATIONARY SOURCES Standards of Performance for Stationary Compression Ignition Internal Combustion Engines Part 60, Subpt. IIII, Table 1 Table 1 to Subpart IIII of Part 60—Emission Standards for...-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection...

  4. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... NEW STATIONARY SOURCES Standards of Performance for Stationary Compression Ignition Internal Combustion Engines Pt. 60, Subpt. IIII, Table 1 Table 1 to Subpart IIII of Part 60—Emission Standards for...-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection...

  5. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... NEW STATIONARY SOURCES Standards of Performance for Stationary Compression Ignition Internal Combustion Engines Pt. 60, Subpt. IIII, Table 1 Table 1 to Subpart IIII of Part 60—Emission Standards for...-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection...

  6. 40 CFR Table 1 to Subpart IIIi of... - Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 7 2012-07-01 2012-07-01 false Emission Standards for Stationary Pre-2007 Model Year Engines With a Displacement of 1 Table 1 to Subpart IIII of Part 60 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR PROGRAMS (CONTINUED) STANDARDS OF PERFORMANCE FOR NEW STATIONARY SOURCES Standards...

  7. Mitigation potential of horizontal ground coupled heat pumps for current and future climatic conditions: UK environmental modelling and monitoring studies

    NASA Astrophysics Data System (ADS)

    García González, Raquel; Verhoef, Anne; Vidale, Pier Luigi; Gan, Guohui; Wu, Yupeng; Hughes, Andrew; Mansour, Majdi; Blyth, Eleanor; Finch, Jon; Main, Bruce

    2010-05-01

    model predictions of soil moisture content and soil temperature with measurements at different GCHP locations over the UK. The combined effect of environment dynamics and horizontal GCHP technical properties on long-term GCHP performance will be assessed using a detailed land surface model (JULES: Joint UK Land Environment Simulator, Meteorological Office, UK) with additional equations embedded describing the interaction between GCHP heat exchangers and the surrounding soil. However, a number of key soil physical processes are currently not incorporated in JULES, such as groundwater flow, which, especially in lowland areas, can have an important effect on the heat flow between soil and HE. Furthermore, the interaction between HE and soil may also cause soil vapour and moisture fluxes. These will affect soil thermal conductivity and hence heat flow between the HE and the surrounding soil, which will in turn influence system performance. The project will address these issues. We propose to drive an improved version of JULES (with equations to simulate GCHP exchange embedded), with long-term gridded (1 km) atmospheric, soil and vegetation data (reflecting current and future environmental conditions) to reliably assess the mitigation potential of GCHPs over the entire domain of the UK, where uptake of GCHPs has been low traditionally. In this way we can identify areas that are most suitable for the installation of GCHPs. Only then recommendations can be made to local and regional governments, for example, on how to improve the mitigation potential in less suitable areas by adjusting GCHP configurations or design.

  8. Day of the year-based prediction of horizontal global solar radiation by a neural network auto-regressive model

    NASA Astrophysics Data System (ADS)

    Gani, Abdullah; Mohammadi, Kasra; Shamshirband, Shahaboddin; Khorasanizadeh, Hossein; Seyed Danesh, Amir; Piri, Jamshid; Ismail, Zuraini; Zamani, Mazdak

    2015-06-01

    The availability of accurate solar radiation data is essential for designing as well as simulating the solar energy systems. In this study, by employing the long-term daily measured solar data, a neural network auto-regressive model with exogenous inputs (NN-ARX) is applied to predict daily horizontal global solar radiation using day of the year as the sole input. The prime aim is to provide a convenient and precise way for rapid daily global solar radiation prediction, for the stations and their immediate surroundings with such an observation, without utilizing any meteorological-based inputs. To fulfill this, seven Iranian cities with different geographical locations and solar radiation characteristics are considered as case studies. The performance of NN-ARX is compared against the adaptive neuro-fuzzy inference system (ANFIS). The achieved results prove that day of the year-based prediction of daily global solar radiation by both NN-ARX and ANFIS models would be highly feasible owing to the accurate predictions attained. Nevertheless, the statistical analysis indicates the superiority of NN-ARX over ANFIS. In fact, the NN-ARX model represents high potential to follow the measured data favorably for all cities. For the considered cities, the attained statistical indicators of mean absolute bias error, root mean square error, and coefficient of determination for the NN-ARX models are in the ranges of 0.44-0.61 kWh/m2, 0.50-0.71 kWh/m2, and 0.78-0.91, respectively.

  9. Day of the year-based prediction of horizontal global solar radiation by a neural network auto-regressive model

    NASA Astrophysics Data System (ADS)

    Gani, Abdullah; Mohammadi, Kasra; Shamshirband, Shahaboddin; Khorasanizadeh, Hossein; Seyed Danesh, Amir; Piri, Jamshid; Ismail, Zuraini; Zamani, Mazdak

    2016-08-01

    The availability of accurate solar radiation data is essential for designing as well as simulating the solar energy systems. In this study, by employing the long-term daily measured solar data, a neural network auto-regressive model with exogenous inputs (NN-ARX) is applied to predict daily horizontal global solar radiation using day of the year as the sole input. The prime aim is to provide a convenient and precise way for rapid daily global solar radiation prediction, for the stations and their immediate surroundings with such an observation, without utilizing any meteorological-based inputs. To fulfill this, seven Iranian cities with different geographical locations and solar radiation characteristics are considered as case studies. The performance of NN-ARX is compared against the adaptive neuro-fuzzy inference system (ANFIS). The achieved results prove that day of the year-based prediction of daily global solar radiation by both NN-ARX and ANFIS models would be highly feasible owing to the accurate predictions attained. Nevertheless, the statistical analysis indicates the superiority of NN-ARX over ANFIS. In fact, the NN-ARX model represents high potential to follow the measured data favorably for all cities. For the considered cities, the attained statistical indicators of mean absolute bias error, root mean square error, and coefficient of determination for the NN-ARX models are in the ranges of 0.44-0.61 kWh/m2, 0.50-0.71 kWh/m2, and 0.78-0.91, respectively.

  10. Sensitivity of desert dust emission modelling to horizontal resolution: the example of the Bodélé Depression

    NASA Astrophysics Data System (ADS)

    Bouet, Christel; Cautenet, Guy; Marticorena, Béatrice; Bergametti, Gilles; Minvielle, Fanny; Schmechtig, Catherine; Laurent, Benoit

    2010-05-01

    Atmospheric aerosols are known to play an important role in the Earth's climate system. However, the quantification of aerosol radiative impact on the Earth's radiative budget is very complex because of the high variability in space and time of aerosol mass and particle number concentrations, and optical properties as well. In many regions, like in desert regions, dust is the largest contribution to aerosol optical thickness [Tegen et al., 1997]. Consequently, it appears fundamental to well represent mineral dust emissions to reduce uncertainties concerning aerosol radiative impact on the Earth's radiative budget. Recently, several studies (e.g. Prospero et al. [2002]) underlined that the Bodélé depression, in northern Chad, is probably the most important source of mineral dust in the world. However many models fail in simulating these large dust emissions. Indeed, dust emission is a threshold phenomenon mainly driven by the intensity of surface wind velocity. Realistic estimates of dust emissions then rely on the quality and accuracy of the surface wind fields. Koren and Kaufman [2004] showed that the reanalysis data (NCEP), which can be used as input data in numerical models, underestimates surface wind velocity in the Bodélé Depression by up to 50%. Such an uncertainty on surface wind velocity cannot allow an accurate simulation of the dust emission. In mesoscale meteorological models, global reanalysis datasets are used to initialize and laterally nudge the models that compute meteorological parameters (like wind velocity) with a finer spatial and temporal resolutions. The question arises concerning the precision of the wind speeds calculated by these models. Using the Regional Atmospheric Modeling System (RAMS, Cotton et al. [2003]) coupled online with the dust production model developed by Marticorena and Bergametti [1995] and recently improved by Laurent et al. [2008] for Africa, the influence of the horizontal resolution of the mesoscale meteorological

  11. MODFLOW-2000, the U.S. Geological Survey modular ground-water model -- Documentation of the Model-Layer Variable-Direction Horizontal Anisotropy (LVDA) capability of the Hydrogeologic-Unit Flow (HUF) package

    USGS Publications Warehouse

    Anderman, Evan R.; Kipp, K.L.; Hill, Mary C.; Valstar, Johan; Neupauer, R.M.

    2002-01-01

    This report documents the model-layer variable-direction horizontal anisotropy (LVDA) capability of the Hydrogeologic-Unit Flow (HUF) Package of MODFLOW-2000. The LVDA capability allows the principal directions of horizontal anisotropy to be different than the model-grid row and column directions, and for the directions to vary on a cell-by-cell basis within model layers. The HUF Package calculates effective hydraulic properties for model grid cells based on hydraulic properties of hydrogeologic units with thicknesses defined independently of the model layers. These hydraulic properties include, among other characteristics, hydraulic conductivity and a horizontal anisotropy ratio. Using the LVDA capability, horizontal anisotropy direction is defined for model grid cells within which one or more hydrogeologic units may occur. For each grid cell, the HUF Package calculates the effective horizontal hydraulic conductivity along the primary direction of anisotropy using the hydrogeologic-unit hydraulic conductivities, and calculates the effective horizontal hydraulic conductivity along the orthogonal anisotropy direction using the effective primary direction hydraulic conductivities and horizontal anisotropy ratios. The direction assigned to the model layer effective primary hydraulic conductivity is specified using a new data set defined by the LVDA capability, when active, to calculate coefficients needed to solve the ground-water flow equation. Use of the LVDA capability is illustrated in four simulation examples, which also serve to verify hydraulic heads, advective-travel paths, and sensitivities calculated using the LVDA capability. This version of the LVDA capability defines variable-direction horizontal anisotropy using model layers, not the hydrogeologic units defined by the HUF Package. This difference needs to be taken into account when designing model layers and hydrogeologic units to produce simulations that accurately represent a given field problem. This

  12. Effect of Ground Proximity on Aerodynamic Characteristics of Two Horizontal-Attitude Jet Vertical-Take-Off-and-Landing Airplane Models

    NASA Technical Reports Server (NTRS)

    Newsom, William A., Jr.

    1960-01-01

    An investigation has been made to study the effect of ground proximity on the aerodynamic characteristics of two jet vertical-take-off-and-landing airplane models in which the fuselage remains in a horizontal attitude for the take-off and landing. The first model (called the tilt-wing model) had a tilting wing-engine assembly which was set at 90 deg incidence for the take-off and landing. The second model, called the deflected-jet model) had a cascade of retractable turning vanes to deflect the exhaust of the horizontally mounted jet engines downward for vertical take-off and landing while the entire model remained in a horizontal attitude. With the models at various heights above the ground in the take-off and landing configuration, the lift, drag, and pitching moment were measured and tuft surveys were made to determine the flow field caused by the jet exhaust. The tilt-wing model experienced a loss of lift of less than 3 percent near the ground. The deflected-jet model, however, suffered losses in lift as high as 45 percent near the ground because of a low pressure region under the model caused by the entrainment of air by the jet exhaust as it spread out along the ground. This loss in lift for the deflected-jet configuration could probably be reduced to less than 5 percent by the use of a longer landing gear and a high wing location.

  13. Numerical modeling of the gamma-gamma density tool responses in horizontal wells with an axial asymmetry.

    PubMed

    Dworak, Dominik; Woźnicka, Urszula; Zorski, Tomasz; Wiącek, Urszula

    2011-01-01

    A signal of a spectrometric gamma-gamma density tool in specific borehole conditions has been numerically calculated. Transport of gamma rays, from a point (137)Cs gamma source situated in a borehole tool, through rock media to detectors, has been simulated using a Monte Carlo code. The influence of heterogeneity of the rock medium surrounding the borehole on the signal of the detectors has been examined. This heterogeneity results from the presence of an interface between two different geological layers, parallel to the borehole wall. The above conditions may occur in horizontal logging, when the borehole is drilled along the boundary of geological layers. It is possible to assess the distance from the boundary on the basis of the responses of the gamma-gamma density tool, using the classic interpretation "spine & ribs" procedure. The effect of different densities of the bordered layers on the tool response has been analyzed. The presented calculations show the wide possibilities of numerical modeling of the complex borehole geometry and solving difficult interpretation problems in nuclear well logging. PMID:20850331

  14. Modelling of heat transfer and solidification processes in horizontal twin-roll casting of magnesium AZ31

    NASA Astrophysics Data System (ADS)

    Miehe, A.; Gross, U.

    2012-07-01

    Magnesium is a desirable material for lightweight construction due to its low density and high strength-to-weight ratio. The disadvantage of low cold formability may be overcome for sheet production by combining casting and forming within horizontal twin-roll casting (TRC). During this process, the molten alloy is fed between two counter-rotating rolls water cooled from the inside. In this paper, numerical simulations using the commercial CFD software Star-CCM+ are presented. The code provides the model based on an incompressible, steady-state solver for laminar flow. To describe the solidification, an exponential increase in viscosity for decreasing temperature is employed in addition to the fraction-of-solid approach based on a linear equation for the release of latent heat. The counter-rotating rolls are exposed to a constant heat transfer coefficient and specify the characteristic velocity of the case. Using the full domain for the simulation of the TRC process provides asymmetric velocity profiles resulting in asymmetric temperature profiles and thus temperature differences between the two rolls. Symmetric results should not be enforced by using only half domain as the asymmetric profiles evoke recirculation zones differing in size which might influence the solidification rates.

  15. Indian summer monsoon rainfall simulation and prediction skill in the CFSv2 coupled model: Impact of atmospheric horizontal resolution

    NASA Astrophysics Data System (ADS)

    Ramu, Dandi A.; Sabeerali, C. T.; Chattopadhyay, Rajib; Rao, D. Nagarjuna; George, Gibies; Dhakate, A. R.; Salunke, K.; Srivastava, A.; Rao, Suryachandra A.

    2016-03-01

    This study compares the simulation and prediction skill of the Indian summer monsoon at two different horizontal resolutions viz., T126 (~100 km) and T382 (~38 km) using 28 years of hindcast runs of the National Centers for Environmental Prediction Climate Forecast System version 2 (CFSv2) model. It is found that the simulation of the mean state of the South Asian summer monsoon, its variance, and prediction skill of the all India summer monsoon rainfall (AISMR) are better represented in the high-resolution configuration (T382) of the CFSv2 compared to the low-resolution (T126) configuration. In the high-resolution run, the systematic bias in the teleconnection between the AISMR and Indian Ocean Dipole (IOD) has considerably reduced and the teleconnections between the AISMR and El Niño-Southern Oscillation (ENSO) remained same. We hypothesize that the better simulation of mean climate and IOD-AISMR teleconnection in high-resolution configuration (T382) of CFSv2 are responsible for the improved prediction skill of AISMR in T382 configuration. Although the T382 configuration of CFSv2 has shown a significant improvement in the simulation and prediction of Indian summer monsoon as compared to the T126 configuration, several parallel efforts are still essential to understand the processes controlling some of the systematic biases of CFSv2 and those efforts are underway as part of the Monsoon Mission project.

  16. Evaluation of techniques for computer modeling and real time control of a horizontal axis wind turbine blade

    NASA Astrophysics Data System (ADS)

    Wesenberg, Alan

    1995-05-01

    Wind power generating turbines operate under constant as well as rapidly changing conditions. With fixed pitch blades, many wind turbines are allowed to operate regardless of wind conditions as long as they are able to produce more electricity than it takes to get them started. However, the lifecycle of the turbine blades is often much shorter than expected because of the unsteady aerodynamic environment under which they rotate. Therefore, the National Renewable Energy Laboratory (NREL) has implemented a testing program to determine the aerodynamic conditions, and the frequency with which they occur, which cause the largest amount of fatigue on their variable pitch, three bladed downwind horizontal axis wind turbine (HAWT). Different techniques will be examined for analytically modeling the flow conditions with separation over a rotating turbine blade. Then, some different techniques for implementing a feedback control loop will be investigated to optimize the movement of the variable pitch blades on the NREL HAWT. The different methods analyzed will fall in the two-dimensional, incompressible area with most also being for steady state conditions. The final objective is to provide the reader with a background in dealing with the aerodynamic conditions surrounding a rotating wind turbine in an unsteady aerodynamic environment.

  17. Simulation of the Indian and East-Asian summer monsoon in the ECMWF model: Sensitivity to horizontal resolution

    SciTech Connect

    Sperber, K.R.; Potter, G.L.; Boyle, J.S.; Hameed, S.

    1993-11-01

    The ability of the ECMWF model (Cycle 33) to simulate the Indian and East Asian summer monsoon is evaluated at four different horizontal resolutions: T21, T42, T63, and T106. Generally, with respect to the large scale features of the circulation, the largest differences among the simulations occur at T42 relative to T21. However, on regional scales, important differences among the high frequency temporal variabilitY serve as a further critical test of the model`s ability to simulate the monsoon. More generally, the results indicate the importance of evaluating high frequency time scales as a component of the climate system. T106 best captures both the spatial and temporal characteristics of the Indian and East Asian Monsoon, while T42 fails to correctly simulate the sequence and development of synoptic scale milestones that characterize the monsoon flow. In particular, T106 is superior at simulating the development and migration of the monsoon trough over the Bay of Bengal. In the T42 simulation, the development of the monsoon occurs one month earlier than typically observed. At this time the trough is incorrectly located adjacent to the east coast of India which results in an underestimate of precipitation over the Burma/Thailand region. This early establishment of the monsoon trough affects the evolution of the East-Asian monsoon and yields excessive preseason rainfall over the Mei-yu region. EOF analysis of precipitation over China indicates that T106 best simulates the Mei-yu mode of variability associated with an oscillation of the rainband that gives rise to periods of enhanced rainfall over the Yangize River Valley. The coarse resolution of T21 precludes simulation of the aforementioned regional scale monsoon flows.

  18. Early warning of freshwater salinization due to upward brine displacement by species transport simulations combined with a hydrochemical genesis model

    NASA Astrophysics Data System (ADS)

    Langer, Maria; Kühn, Michael

    2016-04-01

    Shallow groundwater resources could be possibly affected by intruding brines, which are displaced along hydraulically conductive faults as result of subsurface activities like CO2 injection. To avoid salinization of potable freshwater aquifers an early detection of intruding saline water is necessary, especially in regions where an initial geogenic salinization already exists. Our study is based on work of Tillner et al. [1] and Langer et al. [2] who investigated the influence of permeable fault systems on brine displacement for the prospective storage site Beeskow-Birkholz in the Northeast German Basin. With a 3D regional scale model considering the deep groundwater system, they demonstrated that the existence of hydraulically conductive faults is not necessarily an exclusion criterion for potential injection sites, because salinization of shallower aquifers strongly depends on the effective damage zone volume, the initial salinity distribution and overlying reservoirs [2], while permeability of fault zones does not influence salinization of shallower aquifers significantly [1]. Here we extracted a 2D cross section regarding the upper 220 m of the study area mainly represented by shallow freshwater aquifers, but also considering an initial geogenic salinization [3]. We took flow rates of the intruding brines from the previous studies [2] and implemented species transport simulations with the program code SHEMAT [4]. Results are investigated and interpreted with the hydrochemical genesis model GEBAH [5] which has been already applied as early warning of saltwater intrusions into freshwater aquifers and surface water [6]. GEBAH allows a categorization of groundwater by the ion ratios of the dissolved components and offers a first indicative determination for an existence and the intensity of saline water intrusion in shallow groundwater aquifer, independent of the concentration of the solution. With our model we investigated the migration of saline water through a

  19. Development and validation of a computational finite element model of the rabbit upper airway: simulations of mandibular advancement and tracheal displacement.

    PubMed

    Amatoury, Jason; Cheng, Shaokoon; Kairaitis, Kristina; Wheatley, John R; Amis, Terence C; Bilston, Lynne E

    2016-04-01

    The mechanisms leading to upper airway (UA) collapse during sleep are complex and poorly understood. We previously developed an anesthetized rabbit model for studying UA physiology. On the basis of this body of physiological data, we aimed to develop and validate a two-dimensional (2D) computational finite element model (FEM) of the passive rabbit UA and peripharyngeal tissues. Model geometry was reconstructed from a midsagittal computed tomographic image of a representative New Zealand White rabbit, which included major soft (tongue, soft palate, constrictor muscles), cartilaginous (epiglottis, thyroid cartilage), and bony pharyngeal tissues (mandible, hard palate, hyoid bone). Other UA muscles were modeled as linear elastic connections. Initial boundary and contact definitions were defined from anatomy and material properties derived from the literature. Model parameters were optimized to physiological data sets associated with mandibular advancement (MA) and caudal tracheal displacement (TD), including hyoid displacement, which featured with both applied loads. The model was then validated against independent data sets involving combined MA and TD. Model outputs included UA lumen geometry, peripharyngeal tissue displacement, and stress and strain distributions. Simulated MA and TD resulted in UA enlargement and nonuniform increases in tissue displacement, and stress and strain. Model predictions closely agreed with experimental data for individually applied MA, TD, and their combination. We have developed and validated an FEM of the rabbit UA that predicts UA geometry and peripharyngeal tissue mechanical changes associated with interventions known to improve UA patency. The model has the potential to advance our understanding of UA physiology and peripharyngeal tissue mechanics. PMID:26769952

  20. Displacement analysis of diagnostic ultrasound backscatter: a methodology for characterizing, modeling, and monitoring high intensity focused ultrasound therapy.

    PubMed

    Speyer, Gavriel; Kaczkowski, Peter J; Brayman, Andrew A; Crum, Lawrence A

    2010-07-01

    Accurate monitoring of high intensity focused ultrasound (HIFU) therapy is critical for widespread clinical use. Pulse-echo diagnostic ultrasound (DU) is known to exhibit temperature sensitivity through relative changes in time-of-flight between two sets of radio frequency (RF) backscatter measurements, one acquired before and one after therapy. These relative displacements, combined with knowledge of the exposure protocol, material properties, heat transfer, and measurement noise statistics, provide a natural framework for estimating the administered heating, and thereby therapy. The proposed method, termed displacement analysis, identifies the relative displacements using linearly independent displacement patterns, or modes, each induced by a particular time-varying heating applied during the exposure interval. These heating modes are themselves linearly independent. This relationship implies that a linear combination of displacement modes aligning the DU measurements is the response to an identical linear combination of heating modes, providing the heating estimate. Furthermore, the accuracy of coefficient estimates in this approximation is determined a priori, characterizing heating, thermal dose, and temperature estimates for any given protocol. Predicted performance is validated using simulations and experiments in alginate gel phantoms. Evidence for a spatially distributed interaction between temperature and time-of-flight changes is presented. PMID:20649206

  1. Hydrological modeling of geophysical parameters of arboviral and protozoan disease vectors in Internally Displaced People camps in Gulu, Uganda

    PubMed Central

    Jacob, Benjamin G; Muturi, Ephantus J; Caamano, Erick X; Gunter, James T; Mpanga, Enoch; Ayine, Robert; Okelloonen, Joseph; Nyeko, Jack Pen-Mogi; Shililu, Josephat I; Githure, John I; Regens, James L; Novak, Robert J; Kakoma, Ibulaimu

    2008-01-01

    Background The aim of this study was to determine if remotely sensed data and Digital Elevation Model (DEM) can test relationships between Culex quinquefasciatus and Anopheles gambiae s.l. larval habitats and environmental parameters within Internally Displaced People (IDP) campgrounds in Gulu, Uganda. A total of 65 georeferenced aquatic habitats in various IDP camps were studied to compare the larval abundance of Cx. quinquefasciatus and An. gambiae s.l. The aquatic habitat dataset were overlaid onto Land Use Land Cover (LULC) maps retrieved from Landsat imagery with 150 m × 150 m grid cells stratified by levels of drainage. The LULC change was estimated over a period of 14 years. Poisson regression analyses and Moran's I statistics were used to model relationships between larval abundance and environmental predictors. Individual larval habitat data were further evaluated in terms of their covariations with spatial autocorrelation by regressing them on candidate spatial filter eigenvectors. Multispectral QuickBird imagery classification and DEM-based GIS methods were generated to evaluate stream flow direction and accumulation for identification of immature Cx. quinquefasciatus and An. gambiae s.l. and abundance. Results The main LULC change in urban Gulu IDP camps was non-urban to urban, which included about 71.5 % of the land cover. The regression models indicate that counts of An. gambiae s.l. larvae were associated with shade while Cx. quinquefasciatus were associated with floating vegetation. Moran's I and the General G statistics for mosquito density by species and instars, identified significant clusters of high densities of Anopheles; larvae, however, Culex are not consistently clustered. A stepwise negative binomial regression decomposed the immature An. gambiae s.l. data into empirical orthogonal bases. The data suggest the presence of roughly 11% to 28 % redundant information in the larval count samples. The DEM suggest a positive correlation for Culex

  2. Revised Phylogeny and Novel Horizontally Acquired Virulence Determinants of the Model Soft Rot Phytopathogen Pectobacterium wasabiae SCC3193

    PubMed Central

    Koskinen, Patrik; Nokso-Koivisto, Jussi; Pasanen, Miia; Broberg, Martin; Plyusnin, Ilja; Törönen, Petri; Holm, Liisa; Pirhonen, Minna; Palva, E. Tapio

    2012-01-01

    Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot

  3. Revised phylogeny and novel horizontally acquired virulence determinants of the model soft rot phytopathogen Pectobacterium wasabiae SCC3193.

    PubMed

    Nykyri, Johanna; Niemi, Outi; Koskinen, Patrik; Nokso-Koivisto, Jussi; Pasanen, Miia; Broberg, Martin; Plyusnin, Ilja; Törönen, Petri; Holm, Liisa; Pirhonen, Minna; Palva, E Tapio

    2012-01-01

    Soft rot disease is economically one of the most devastating bacterial diseases affecting plants worldwide. In this study, we present novel insights into the phylogeny and virulence of the soft rot model Pectobacterium sp. SCC3193, which was isolated from a diseased potato stem in Finland in the early 1980s. Genomic approaches, including proteome and genome comparisons of all sequenced soft rot bacteria, revealed that SCC3193, previously included in the species Pectobacterium carotovorum, can now be more accurately classified as Pectobacterium wasabiae. Together with the recently revised phylogeny of a few P. carotovorum strains and an increasing number of studies on P. wasabiae, our work indicates that P. wasabiae has been unnoticed but present in potato fields worldwide. A combination of genomic approaches and in planta experiments identified features that separate SCC3193 and other P. wasabiae strains from the rest of soft rot bacteria, such as the absence of a type III secretion system that contributes to virulence of other soft rot species. Experimentally established virulence determinants include the putative transcriptional regulator SirB, two partially redundant type VI secretion systems and two horizontally acquired clusters (Vic1 and Vic2), which contain predicted virulence genes. Genome comparison also revealed other interesting traits that may be related to life in planta or other specific environmental conditions. These traits include a predicted benzoic acid/salicylic acid carboxyl methyltransferase of eukaryotic origin. The novelties found in this work indicate that soft rot bacteria have a reservoir of unknown traits that may be utilized in the poorly understood latent stage in planta. The genomic approaches and the comparison of the model strain SCC3193 to other sequenced Pectobacterium strains, including the type strain of P. wasabiae, provides a solid basis for further investigation of the virulence, distribution and phylogeny of soft rot

  4. Future changes in regional precipitation simulated by a half-degree coupled climate model: Sensitivity to horizontal resolution

    DOE PAGESBeta

    Shields, Christine A.; Kiehl, Jeffrey T.; Meehl, Gerald A.

    2016-06-02

    The global fully coupled half-degree Community Climate System Model Version 4 (CCSM4) was integrated for a suite of climate change ensemble simulations including five historical runs, five Representative Concentration Pathway 8.5 [RCP8.5) runs, and a long Pre-Industrial control run. This study focuses on precipitation at regional scales and its sensitivity to horizontal resolution. The half-degree historical CCSM4 simulations are compared to observations, where relevant, and to the standard 1° CCSM4. Both the halfdegree and 1° resolutions are coupled to a nominal 1° ocean. North American and South Asian/Indian monsoon regimes are highlighted because these regimes demonstrate improvements due to highermore » resolution, primarily because of better-resolved topography. Agriculturally sensitive areas are analyzed and include Southwest, Central, and Southeast U.S., Southern Europe, and Australia. Both mean and extreme precipitation is discussed for convective and large-scale precipitation processes. Convective precipitation tends to decrease with increasing resolution and large-scale precipitation tends to increase. Improvements for the half-degree agricultural regions can be found for mean and extreme precipitation in the Southeast U.S., Southern Europe, and Australian regions. Climate change responses differ between the model resolutions for the U.S. Southwest/Central regions and are seasonally dependent in the Southeast and Australian regions. Both resolutions project a clear drying signal across Southern Europe due to increased greenhouse warming. As a result, differences between resolutions tied to the representation of convective and large-scale precipitation play an important role in the character of the climate change and depend on regional influences.« less

  5. Wind-Tunnel Investigation of Some Effects of Wing Sweep and Horizontal-Tail Height on the Static Stability of an Airplane Model at Transonic Speeds

    NASA Technical Reports Server (NTRS)

    Fisher, Lewis R.; Williams, James L.

    1958-01-01

    A research model of an airplane with a configuration suitable for supersonic flight was tested at transonic speeds in order to establish the effects on longitudinal and lateral stability of certain changes in both wing sweep and height of the horizontal tail. Two wings of aspect ratio 3 and taper ratio 0.15, one having the quarter-chord line swept back 30 deg and the other 45 deg, were each tested with the horizontal tail of the model in a low and in a high position. One configuration was also tested with fuselage strakes. The tests were made at Mach numbers from 0.60 to 1.17 and Reynolds numbers from 1.9 x 10(exp 6) to 2.6 x 10(exp 6). The results indicated that a low horizontal-tail position (below the wing-chord plane) gave positive longitudinal stability for the model for all angles of attack used (angles of attack up to 24 deg); whereas, a higher tail position (above the wing-chord plane) resulted in a large reduction in stability at moderate angles of attack. With the higher horizontal tail, the 30 deg-swept-wing model had somewhat more stability than the 45 deg-swept-wing model at subsonic Mach numbers. With the lower tail, the 45 deg-swept-wing model had slightly more stability at all Mach numbers. The model with the 30 deg swept wing had greater directional stability with the tail in the higher rather than the lower position, but the opposite was true for the 45 deg-swept-wing model. The directional stability decreased sharply at high angles of attack; this characteristic was alleviated by the use of fuselage strakes which, however, proved to be detrimental to the longitudinal stability of the model tested.

  6. Some thoughts on error-contributions to reconstruct 3D coseismic displacement field using the model of combining multiple independent InSAR

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Zhang, Jingfa; Luo, Yi

    2012-07-01

    Interferometric Synthetic Aperture Radar (InSAR) has proved an immensely powerful tool in studying earthquakes with millimetre-scale accuracy at a high spatial resolution. However, each interferogram records only the component of displacement in the direction of the satellite line of sight (LOS). Thus previous InSAR studies of displacement due to earthquakes were generally limited to one or two components of the surface displacement field. Three- dimensional (3D) surface displacement maps can provide a more comprehensive understanding of source geometry associated with earthquake. By combining interferograms from multiple look angles, it is possible to constrain the three-dimensional components of displacement [Jung et al., 2011; Wright, et al., 2004; Hong et al., 2010]. In this work, we take 2008 Gaize Ms6.9 earthquake (Tibet) for example, derive LOS surface displacement from several paths of ENVISAT ASAR images (Image mode: Track 348, descending pass; Track 341, 427, and 155, ascending pass. ScanSAR mode: Track 341, 112, 155, and 384, ascending pass), and reconstruct the 3D coseismic displacement field with the model named multiple independent InSAR with different viewing angles. Because it is difficult to distinguish tectonic signal from phase noise (eg. orbital errors, atmospheric errors, and unwrapping errors), these error-contributions may be propagated to the 3D coseismic components (vertical, north, east). In addition, for ENVISAT ASAR, it is worth notice that the radar antenna is fixed with respect to the current satellite, which may lead to different LOS observations with nearly identical viewing angles in parallel passes. Thus, when inverting 3D components with least square solution, InSAR observation errors may be magnified by the ill-conditioned system of equations in the solution. Although the ill-conditioned system of equations may result in bad solution, some InSAR observation errors can be detected by the system. In our study, we will introduce the

  7. Characterization of Horizontal Gas-Liquid Two-Phase Flow Using Markov Model-Based Complex Network

    NASA Astrophysics Data System (ADS)

    Hu, Li-Dan; Jin, Ning-De; Gao, Zhong-Ke

    2013-05-01

    Horizontal gas-liquid two-phase flow widely exists in many physical systems and chemical engineering processes. Compared with vertical upward gas-liquid two-phase flow, investigations on dynamic behavior underlying horizontal gas-liquid flows are quite limited. Complex network provides a powerful framework for time series analysis of complex dynamical systems. We use a network generation method based on Markov transition probability to infer directed weighted complex networks from signals measured from horizontal gas-liquid two-phase flow experiment and find that the networks corresponding to different flow patterns exhibit different network structure. To investigate the dynamic characteristics of horizontal gas-liquid flows, we construct a number of complex networks under different flow conditions, and explore the network indices for each constructed network. In addition, we investigate the sample entropy of different flow patterns. Our results suggest that the network statistic can well represent the complexity in the transition among different flow patterns and further allows characterizing the interface fluctuation behavior in horizontal gas-liquid two-phase flow.

  8. Modeling, design, packing and experimental analysis of liquid-phase shear-horizontal surface acoustic wave sensors

    NASA Astrophysics Data System (ADS)

    Pollard, Thomas B

    Recent advances in microbiology, computational capabilities, and microelectromechanical-system fabrication techniques permit modeling, design, and fabrication of low-cost, miniature, sensitive and selective liquid-phase sensors and lab-on-a-chip systems. Such devices are expected to replace expensive, time-consuming, and bulky laboratory-based testing equipment. Potential applications for devices include: fluid characterization for material science and industry; chemical analysis in medicine and pharmacology; study of biological processes; food analysis; chemical kinetics analysis; and environmental monitoring. When combined with liquid-phase packaging, sensors based on surface-acoustic-wave (SAW) technology are considered strong candidates. For this reason such devices are focused on in this work; emphasis placed on device modeling and packaging for liquid-phase operation. Regarding modeling, topics considered include mode excitation efficiency of transducers; mode sensitivity based on guiding structure materials/geometries; and use of new piezoelectric materials. On packaging, topics considered include package interfacing with SAW devices, and minimization of packaging effects on device performance. In this work novel numerical models are theoretically developed and implemented to study propagation and transduction characteristics of sensor designs using wave/constitutive equations, Green's functions, and boundary/finite element methods. Using developed simulation tools that consider finite-thickness of all device electrodes, transduction efficiency for SAW transducers with neighboring uniform or periodic guiding electrodes is reported for the first time. Results indicate finite electrode thickness strongly affects efficiency. Using dense electrodes, efficiency is shown to approach 92% and 100% for uniform and periodic electrode guiding, respectively; yielding improved sensor detection limits. A numerical sensitivity analysis is presented targeting viscosity

  9. The Effects of Horizontal-Tail Location and Wing Modifications on the High-Speed Stability and Control Characteristics of a 01.17-Scale Model of the McDonnell XF2H-1 Airplane (TED No, NACA DE336)

    NASA Technical Reports Server (NTRS)

    Emerson, Horace F.; Axelson, John A.

    1949-01-01

    An additional series of high-speed wind-tunnel tests of a modified 0.17-scale model of the McDonnell XF2H-1 airplane was conducted to evaluate the effects of a reduction in the thickness-to-chord ratios of the tail planes, the displacement of the horizontal tail relative to the vertical tail, and the extension of the trailing edge of the wing. Two tail-intersection fairings designed to improve the flow at the tail were also tested. The pitching-moment characteristics of the model were improved slightly by the use of the thinner tail sections. Rearward or rearward and downward displacements of the horizontal tail increased the critical Mach number at the tail intersection from 0.725 to a maximum of 0.80, but caused an excessive change in pitching-moment coefficient at the higher Mach numbers. Extending the trailing edge of the wing did not improve the static longitudinal-stability characteristics, but increased the pitching-down tendency between 0.725 and 0.825 Mach numbers prior to the pitching-up tendency. The extended wing did, however, increase the Mach numbers at which these tendencies occurred. The increase in the Mach numbers of divergence and the tuft studies indicate a probable increase in the buffet limit of the prototype airplane. No perceptible improvement of flow at the tail intersection was observed with the two fairings tested on the forward tail configuration.

  10. Body-composition assessment in infancy: Air-displacement plethysmography compared with a reference 4-compartment model

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Background: A better understanding of the associations of early infant nutrition and growth with adult health requires accurate assessment of body composition in infancy. Objective: This study evaluated the performance of an infant-sized air-displacement plethysmograph (PEA POD Infant Body Compositi...

  11. Use of Displacement Damage Dose in an Engineering Model of GaAs Solar Cell Radiation Damage

    NASA Technical Reports Server (NTRS)

    Morton, T. L.; Chock, R.; Long, K. J.; Bailey, S.; Messenger, S. R.; Walters, R. J.; Summers, G. P.

    2005-01-01

    Current methods for calculating damage to solar cells are well documented in the GaAs Solar Cell Radiation Handbook (JPL 96-9). An alternative, the displacement damage dose (D(sub d)) method, has been developed by Summers, et al. This method is currently being implemented in the SAVANT computer program.

  12. Response of precipitation extremes to idealized global warming in an aqua-planet climate model: Towards robust projection across different horizontal resolutions

    SciTech Connect

    Li, F.; Collins, W.D.; Wehner, M.F.; Williamson, D.L.; Olson, J.G.

    2011-04-15

    Current climate models produce quite heterogeneous projections for the responses of precipitation extremes to future climate change. To help understand the range of projections from multimodel ensembles, a series of idealized 'aquaplanet' Atmospheric General Circulation Model (AGCM) runs have been performed with the Community Atmosphere Model CAM3. These runs have been analysed to identify the effects of horizontal resolution on precipitation extreme projections under two simple global warming scenarios. We adopt the aquaplanet framework for our simulations to remove any sensitivity to the spatial resolution of external inputs and to focus on the roles of model physics and dynamics. Results show that a uniform increase of sea surface temperature (SST) and an increase of low-to-high latitude SST gradient both lead to increase of precipitation and precipitation extremes for most latitudes. The perturbed SSTs generally have stronger impacts on precipitation extremes than on mean precipitation. Horizontal model resolution strongly affects the global warming signals in the extreme precipitation in tropical and subtropical regions but not in high latitude regions. This study illustrates that the effects of horizontal resolution have to be taken into account to develop more robust projections of precipitation extremes.

  13. Impact of horizontal resolution on simulation of precipitation extremes in an aqua-planet version of Community Atmospheric Model (CAM3)

    NASA Astrophysics Data System (ADS)

    Li, Fuyu; Collins, William D.; Wehner, Michael F.; Williamson, David L.; Olson, Jerry G.; Algieri, Christopher

    2011-10-01

    One key question regarding current climate models is whether the projection of climate extremes converges to a realistic representation as the spatial and temporal resolutions of the model are increased. Ideally the model extreme statistics should approach a fixed distribution once the resolutions are commensurate with the characteristic length and time scales of the processes governing the formation of the extreme phenomena of interest. In this study, a series of AGCM runs with idealized 'aquaplanet-steady-state' boundary conditions have been performed with the Community Atmosphere Model CAM3 to investigate the effect of horizontal resolution on climate extreme simulations. The use of the aquaplanet framework highlights the roles of model physics and dynamics and removes any apparent convergence in extreme statistics due to better resolution of surface boundary conditions and other external inputs. Assessed at a same large spatial scale, the results show that the horizontal resolution and time step have strong effects on the simulations of precipitation extremes. The horizontal resolution has a much stronger impact on precipitation extremes than on mean precipitation. Updrafts are strongly correlated with extreme precipitation at tropics at all the resolutions, while positive low-tropospheric temperature anomalies are associated with extreme precipitation at mid-latitudes.

  14. Response of precipitation extremes to idealized global warming in an aqua-planet climate model: towards a robust projection across different horizontal resolutions

    NASA Astrophysics Data System (ADS)

    Li, Fuyu; Collins, William D.; Wehner, Michael F.; Williamson, David L.; Olson, Jerry G.

    2011-10-01

    Current climate models produce quite heterogeneous projections for the responses of precipitation extremes to future climate change. To help understand the range of projections from multimodel ensembles, a series of idealized 'aquaplanet' Atmospheric General Circulation Model (AGCM) runs have been performed with the Community Atmosphere Model CAM3. These runs have been analysed to identify the effects of horizontal resolution on precipitation extreme projections under two simple global warming scenarios. We adopt the aquaplanet framework for our simulations to remove any sensitivity to the spatial resolution of external inputs and to focus on the roles of model physics and dynamics. Results show that a uniform increase of sea surface temperature (SST) and an increase of low-to-high latitude SST gradient both lead to increase of precipitation and precipitation extremes for most latitudes. The perturbed SSTs generally have stronger impacts on precipitation extremes than on mean precipitation. Horizontal model resolution strongly affects the global warming signals in the extreme precipitation in tropical and subtropical regions but not in high latitude regions. This study illustrates that the effects of horizontal resolution have to be taken into account to develop more robust projections of precipitation extremes.

  15. Impact of horizontal resolution on simulation of precipitation extremes in an aqua-planet version of the Community Atmosphere Model (CAM)

    SciTech Connect

    Li, F.; Collins, W.D.; Wehner, M.F.; Williamson, D.L.; Olson, J.G.; Algieri, C.

    2011-03-01

    One key question regarding current climate models is whether the projection of climate extremes converges to a realistic representation as the spatial and temporal resolutions of the model are increased. Ideally the model extreme statistics should approach a fixed distribution once the resolutions are commensurate with the characteristic length and time scales of the processes governing the formation of the extreme phenomena of interest. In this study, a series of AGCM runs with idealized 'aquaplanet-steady-state' boundary conditions have been performed with the Community Atmosphere Model CAM3 to investigate the effect of horizontal resolution on climate extreme simulations. The use of the aquaplanet framework highlights the roles of model physics and dynamics and removes any apparent convergence in extreme statistics due to better resolution of surface boundary conditions and other external inputs. Assessed at a same large spatial scale, the results show that the horizontal resolution and time step have strong effects on the simulations of precipitation extremes. The horizontal resolution has a much stronger impact on precipitation extremes than on mean precipitation. Updrafts are strongly correlated with extreme precipitation at tropics at all the resolutions, while positive low-tropospheric temperature anomalies are associated with extreme precipitation at mid-latitudes.

  16. Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics.

    PubMed

    Clotet, Xavier; Santucci, Stéphane; Ortín, Jordi

    2016-01-01

    We report the results of an experimental investigation of the spatiotemporal dynamics of stable imbibition fronts in a disordered medium, in the regime of capillary disorder, for a wide range of experimental conditions. We have used silicone oils of various viscosities μ and nearly identical oil-air surface tension, and forced them to slowly invade a model open fracture at very different flow rates v. In this second part of the study we have carried out a scale-dependent statistical analysis of the front dynamics. We have specifically analyzed the influence of μ and v on the statistical properties of the velocity V_{ℓ}, the spatial average of the local front velocities over a window of lateral size ℓ. We have varied ℓ from the local scale defined by our spatial resolution up to the lateral system size L. Even though the imposed flow rate is constant, the signals V_{ℓ}(t) present very strong fluctuations which evolve systematically with the parameters μ, v, and ℓ. We have verified that the non-Gaussian fluctuations of the global velocity V_{ℓ}(t) are very well described by a generalized Gumbel statistics. The asymmetric shape and the exponential tail of those distributions are controlled by the number of effective degrees of freedom of the imbibition fronts, given by N_{eff}=ℓ/ℓ_{c} (the ratio of the lateral size of the measuring window ℓ to the correlation length ℓ_{c}∼1/sqrt[μv]). The large correlated excursions of V_{ℓ}(t) correspond to global avalanches, which reflect extra displacements of the imbibition fronts. We show that global avalanches are power-law distributed, both in sizes and durations, with robustly defined exponents-independent of μ, v, and ℓ. Nevertheless, the exponential upper cutoffs of the distributions evolve systematically with those parameters. We have found, moreover, that maximum sizes ξ_{S} and maximum durations ξ_{T} of global avalanches are not controlled by the same mechanism. While ξ_{S} are also

  17. Modeling and visualization of carrier motion in organic films by optical second harmonic generation and Maxwell-displacement current

    NASA Astrophysics Data System (ADS)

    Iwamoto, Mitsumasa; Manaka, Takaaki; Taguchi, Dai

    2015-09-01

    The probing and modeling of carrier motions in materials as well as in electronic devices is a fundamental research subject in science and electronics. According to the Maxwell electromagnetic field theory, carriers are a source of electric field. Therefore, by probing the dielectric polarization caused by the electric field arising from moving carriers and dipoles, we can find a way to visualize the carrier motions in materials and in devices. The techniques used here are an electrical Maxwell-displacement current (MDC) measurement and a novel optical method based on the electric field induced optical second harmonic generation (EFISHG) measurement. The MDC measurement probes changes of induced charge on electrodes, while the EFISHG probes nonlinear polarization induced in organic active layers due to the coupling of electron clouds of molecules and electro-magnetic waves of an incident laser beam in the presence of a DC field caused by electrons and holes. Both measurements allow us to probe dynamical carrier motions in solids through the detection of dielectric polarization phenomena originated from dipolar motions and electron transport. In this topical review, on the basis of Maxwell’s electro-magnetism theory of 1873, which stems from Faraday’s idea, the concept for probing electron and hole transport in solids by using the EFISHG is discussed in comparison with the conventional time of flight (TOF) measurement. We then visualize carrier transit in organic devices, i.e. organic field effect transistors, organic light emitting diodes, organic solar cells, and others. We also show that visualizing an EFISHG microscopic image is a novel way for characterizing anisotropic carrier transport in organic thin films. We also discuss the concept of the detection of rotational dipolar motions in monolayers by means of the MDC measurement, which is capable of probing the change of dielectric spontaneous polarization formed by dipoles in organic monolayers. Finally we

  18. Experimental study of stable imbibition displacements in a model open fracture. II. Scale-dependent avalanche dynamics

    NASA Astrophysics Data System (ADS)

    Clotet, Xavier; Santucci, Stéphane; Ortín, Jordi

    2016-01-01

    We report the results of an experimental investigation of the spatiotemporal dynamics of stable imbibition fronts in a disordered medium, in the regime of capillary disorder, for a wide range of experimental conditions. We have used silicone oils of various viscosities μ and nearly identical oil-air surface tension, and forced them to slowly invade a model open fracture at very different flow rates v . In this second part of the study we have carried out a scale-dependent statistical analysis of the front dynamics. We have specifically analyzed the influence of μ and v on the statistical properties of the velocity Vℓ, the spatial average of the local front velocities over a window of lateral size ℓ . We have varied ℓ from the local scale defined by our spatial resolution up to the lateral system size L . Even though the imposed flow rate is constant, the signals Vℓ(t ) present very strong fluctuations which evolve systematically with the parameters μ , v , and ℓ . We have verified that the non-Gaussian fluctuations of the global velocity Vℓ(t ) are very well described by a generalized Gumbel statistics. The asymmetric shape and the exponential tail of those distributions are controlled by the number of effective degrees of freedom of the imbibition fronts, given by Neff=ℓ /ℓc (the ratio of the lateral size of the measuring window ℓ to the correlation length ℓc˜1 /√{μ v } ). The large correlated excursions of Vℓ(t ) correspond to global avalanches, which reflect extra displacements of the imbibition fronts. We show that global avalanches are power-law distributed, both in sizes and durations, with robustly defined exponents—independent of μ , v , and ℓ . Nevertheless, the exponential upper cutoffs of the distributions evolve systematically with those parameters. We have found, moreover, that maximum sizes ξS and maximum durations ξT of global avalanches are not controlled by the same mechanism. While ξS are also determined by

  19. PIV and Hotwire Measurement and Analysis of Tip Vortices and Turbulent Wake Generated by a Model Horizontal Axis Wind Turbine

    NASA Astrophysics Data System (ADS)

    Green, D.; Tan, Y. M.; Chamorro, L. P.; Arndt, R.; Sotiropoulos, F.; Sheng, J.

    2011-12-01

    Understanding vortical flow structures and turbulence in the wake flow behind a Horizontal Axis Wind Turbine (HAWT) has widespread applications in efficient blade design. Moreover, the knowledge of wake-turbine interactions allows us to devise optimal operational parameters, such as the spatial allocation and control algorithms of wind turbines, for a densely populated wind farm. To understand the influence of tip vortices on energy containing mean flow and turbulence, characteristics of vortical structures and turbulence must be quantified thoroughly. In this study, we conduct phase-locked Particle Image Velocimetry (PIV) measurements of the flow before and after a model HAWT, which is located in a zero-pressure gradient wind tunnel with a cross section of 1.7 × 1.7 m and a test section of 16 m in length. A three-blade model HAWT with a diameter of 605 mm and tip-speed ratio of 5 is used. PIV images are recorded by a 2048 × 2048 CCD camera and streamed at 6 Hz continuously; and phased locked with the passage of the blade at its vertical position. Each PIV measurement covers a 0.13 × 0.13 m2 sample area with the spatial resolution of 63 μm and a vector spacing of 0.5 mm. All experiments are conducted at the free-stream wind speed of 10 m/s. Flow fields at thirty consecutive downstream locations up to six rotor diameters and 144 mid chord lengths are measured. At each location, we obtain at least 10,000 instantaneous PIV realizations or 20,000 images. Three different configurations: single, dual, and trio turbines located at 5 rotor diameter upstream to each other, are examined experimentally. The flow statistics include mean wake velocity distributions, characteristics of tip vortices evolving downstream, fluctuation velocity, turbulent kinetic energy, stresses, and energy spectra. We find that tip vortices decay much faster in the wake of the upstream turbines (multiple-turbine configurations), whereas they maintain the coherence and strength behind a single

  20. Stress-relief displacements induced by drilling--applications to holographic measurements of in situ stress

    SciTech Connect

    Ahrens, T.J.; Smither, C.L.

    1992-04-24

    The holographic stressmeter is an instrument which has been developed at Caltech to allow determination of the complete stress tensor from in situ borehole measurements. The stressmeter uses double-exposure holographic interferometry to record the displacements induced by the drilling of a small sidehole into the borehole wall. The local stresses, which are the result of the far-field stresses, concentrated at the borehole, cause deformation of the surface of the borehole wall in the vicinity of the sidehole. The first part of this study uses a thin infinite elastic plate subjected to plane stress at infinity to model the displacements at the borehole wall. However, the existence of some holograms which were difficult to model closely led us to examine the validity of this model. In order to investigate the problem further, we performed a two-dimensional finite element analysis for an elastic box with a terminated hole. We varied the dimensions of the hole to see what effect the radius and depth of the hole might have on the displacements. The plate model predicts that the depth of the hole should have no effect on the horizontal components of displacement, but the finite element results show that the magnitude of both components of the displacement depends on the depth of the sidehole. After considering these results, we developed a new model for the analysis of stress-relief displacements, following the work of Youngdahl and Sternberg (1965). For holes with a depth-to-diameter ratio greater than unity, the simple plane stress elastic plate solution breaks down and does not adequately model the displacements at the surface of the body and near the hole. Since these are the areas most critical to calculate accurately with the holographic technique, the revised model does a better job of fitting the observed data.

  1. Stress-relief displacements induced by drilling: Applications to holographic measurements of in situ stress

    NASA Astrophysics Data System (ADS)

    Ahrens, T. J.; Smither, C. L.

    1992-04-01

    The holographic stressmeter is an instrument which has been developed at Caltech to allow the determination of the complete stress tensor from in situ borehole measurements. The stressmeter uses double-exposure holographic interferometry to record the displacements induced by the drilling of a small sidehole into the borehole wall. The local stresses, which are the result of the far-field stresses concentrated at the borehole, cause deformation of the surface of the borehole wall in the vicinity of the sidehole. The first part of this study uses a thin infinite elastic plate subjected to plane stress at infinity to model the displacements at the borehole wall. However, the existence of some holograms which were difficult to model closely led us to examine the validity of this model. In order to investigate the problem further, we performed a two-dimensional finite element analysis for an elastic box with a terminated hole. We varied the dimensions of the hole to see what effect the radius and depth of the hole might have on the displacements. The plate model predicts that the depth of the hole should have no effect on the horizontal components of displacement, but the finite element results show that the magnitude of both components of the displacement depends on the depth of the sidehole. After considering these results, we developed a new model for the analysis of stress-relief displacements, following the work of Youngdahl and Sternberg (1965). For holes with a depth-to-diameter ratio greater than unity, the simple plane stress elastic plate solution breaks down and does not adequately model the displacements at the surface of the body and near the hole. Since these are the areas most critical to calculate accurately with the holographic technique, the revised model does a better job of fitting the observed data.

  2. Disparate atomic displacements in skutterudite-type LaFe3CoSb12, a model for thermoelectric behavior.

    PubMed

    Chakoumakos; Sales; Mandrus; Keppens

    1999-06-01

    Mean-square atomic displacements in lanthanum triiron cobalt dodecaantimonide, determined as a function of temperature using single-crystal neutron diffraction, show that the La atom exhibits an anomalously large displacement at room temperature, U(eq) = 0.0196 (9) Å(2), because it is too small to fill the atomic cage formed by the corner-linked octahedral framework of M(4)Sb(12), M = Fe, Co. Site-occupancy refinements show 25% vacancies on the La site and an actual Fe:Co ratio of 2.17:1. Analysis of the temperature dependence of the atomic displacements identifies a significant temperature-independent component for the La atom ascribed to static disorder, which amounts to 19% of the room-temperature value. The large-amplitude rattling of the La atom can be effectively linked to the dramatic decrease of the lattice contribution to the thermal conductivity, which is a key factor for improving the thermoelectric behavior of these materials. This structure-property relationship offers a new paradigm for the exploration of thermoelectric materials. PMID:10927376

  3. Technical report series on global modeling and data assimilation. Volume 2: Direct solution of the implicit formulation of fourth order horizontal diffusion for gridpoint models on the sphere

    NASA Technical Reports Server (NTRS)

    Li, Yong; Moorthi, S.; Bates, J. Ray; Suarez, Max J.

    1994-01-01

    High order horizontal diffusion of the form K Delta(exp 2m) is widely used in spectral models as a means of preventing energy accumulation at the shortest resolved scales. In the spectral context, an implicit formation of such diffusion is trivial to implement. The present note describes an efficient method of implementing implicit high order diffusion in global finite difference models. The method expresses the high order diffusion equation as a sequence of equations involving Delta(exp 2). The solution is obtained by combining fast Fourier transforms in longitude with a finite difference solver for the second order ordinary differential equation in latitude. The implicit diffusion routine is suitable for use in any finite difference global model that uses a regular latitude/longitude grid. The absence of a restriction on the timestep makes it particularly suitable for use in semi-Lagrangian models. The scale selectivity of the high order diffusion gives it an advantage over the uncentering method that has been used to control computational noise in two-time-level semi-Lagrangian models.

  4. RNGCHN: a program to calculate displacement components from dislocations in an elastic half-space with applications for modeling geodetic measurements of crustal deformation

    NASA Astrophysics Data System (ADS)

    Feigl, Kurt L.; Dupré, Emmeline

    1999-07-01

    The RNGCHN program calculates a single component of the displacement field due to a finite or point-source dislocation buried in an elastic half space. This formulation approximates the surface movements produced by earthquake faulting or volcanic intrusion. As such, it is appropriate for modeling crustal deformation measured by geodetic surveying techniques, such as spirit leveling, trilateration, Very Long Baseline Interferometry (VLBI), Global Positioning System (GPS), or especially interferometric analysis of synthetic aperture radar (SAR) images. Examples suggest that this model can fit simple coseismic earthquake signatures to within their measurement uncertainties. The program's input parameters include fault position, depth, length, width, strike, dip, and three components of slip. The output consists of displacement components in the form of an ASCII list or a rectangular array of binary integers. The same program also provides partial derivatives of the displacement component with respect to all 10 input parameters. The FORTRAN source code for the program is in the public domain and available as the compressed tar file rngchn.tar.Z in the directory/pub/GRGS via the Internet by anonymous ftp to spike.cst. cnes.fr. This distribution includes worked examples and a MATLAB interface.

  5. Horizontal drilling developments

    SciTech Connect

    Gust, D.

    1997-05-01

    The advantages of horizontal drilling are discussed. Use of horizontal drilling has climbed in the past half decade as technology and familiarity offset higher costs with higher production rates and greater recoveries from new and existing wells. In essence, all types of horizontal wells expose a larger section of the reservoir to the wellbore with a resulting increase in flow rates. (A horizontal well may also be drilled to provide coning control or to intersect vertical fractures.) Thus, drilling horizontally, both onshore and offshore, reduces the number of wells necessary to develop a field.

  6. Eye-pupil displacement and prediction: effects on residual wavefront in adaptive optics retinal imaging

    PubMed Central

    Kulcsár, Caroline; Raynaud, Henri-François; Garcia-Rissmann, Aurea

    2016-01-01

    This paper studies the effect of pupil displacements on the best achievable performance of retinal imaging adaptive optics (AO) systems, using 52 trajectories of horizontal and vertical displacements sampled at 80 Hz by a pupil tracker (PT) device on 13 different subjects. This effect is quantified in the form of minimal root mean square (rms) of the residual phase affecting image formation, as a function of the delay between PT measurement and wavefront correction. It is shown that simple dynamic models identified from data can be used to predict horizontal and vertical pupil displacements with greater accuracy (in terms of average rms) over short-term time horizons. The potential impact of these improvements on residual wavefront rms is investigated. These results allow to quantify the part of disturbances corrected by retinal imaging systems that are caused by relative displacements of an otherwise fixed or slowy-varying subject-dependent aberration. They also suggest that prediction has a limited impact on wavefront rms and that taking into account PT measurements in real time improves the performance of AO retinal imaging systems. PMID:27231607

  7. Eye-pupil displacement and prediction: effects on residual wavefront in adaptive optics retinal imaging.

    PubMed

    Kulcsár, Caroline; Raynaud, Henri-François; Garcia-Rissmann, Aurea

    2016-03-01

    This paper studies the effect of pupil displacements on the best achievable performance of retinal imaging adaptive optics (AO) systems, using 52 trajectories of horizontal and vertical displacements sampled at 80 Hz by a pupil tracker (PT) device on 13 different subjects. This effect is quantified in the form of minimal root mean square (rms) of the residual phase affecting image formation, as a function of the delay between PT measurement and wavefront correction. It is shown that simple dynamic models identified from data can be used to predict horizontal and vertical pupil displacements with greater accuracy (in terms of average rms) over short-term time horizons. The potential impact of these improvements on residual wavefront rms is investigated. These results allow to quantify the part of disturbances corrected by retinal imaging systems that are caused by relative displacements of an otherwise fixed or slowy-varying subject-dependent aberration. They also suggest that prediction has a limited impact on wavefront rms and that taking into account PT measurements in real time improves the performance of AO retinal imaging systems. PMID:27231607

  8. Displacement measurement of the depth migration of transparent cells

    SciTech Connect

    Yoshida, Makoto; Ishimaru, Ichirou; Ishizaki, Katsumi; Yasokawa, Toshiki; Kuriyama, Shigeki; Masaki, Tsutomu; Nakai, Seiji; Takegawa, Kaoru; Tanaka, Naoyuki

    2006-12-11

    This letter reports a method for displacement measurement of the depth migration of transparent cells. This proposed optical spatial filtering method allows visualization of the transparent cells and determination of depth migration as a horizontal displacement positive or negative first order diffracted light on the detector surface. When the sample is displaced upward or downward from the focal plane, first and negative first order diffracted light form images at a different point as a light circle. The coordinates of these two light circles on the detector surface change places when the displacement of depth migration moves to the opposite direction.

  9. The Effects of Drift and Displacement Motion on Dynamic Visual Acuity

    ERIC Educational Resources Information Center

    Aznar-Casanova, J. Antonio; Quevedo, Lluisa; Sinnett, Scott

    2005-01-01

    Dynamic Visual Acuity (DVA) can be measured from two types of equivalently considered movement referred to as drifting-motion and displacement-motion. Displacement motion can be best described as the horizontal displacement of a stimulus, thus implying pursuit eye movements, and involves moving the stimulus from the fixation point of gaze towards…

  10. Comparing (semi-) analytic solutions used to model the impact of deep carbon injection on the displacement and pressurization of the resident brine

    NASA Astrophysics Data System (ADS)

    Bandilla, K.; Kraemer, S. R.

    2009-12-01

    Injection of carbon dioxide into deep saline formations is seen as one possible technology for mitigating carbon emissions from utilities. The safety of the sequestered carbon dioxide is the focus of many studies with leakage through faults or abandoned wells as some of the main failure mechanisms. The focus of this study is on the displacement of resident brine and the resulting changes in pressure due to the injection of large volumes of super-critical phase carbon dioxide into the subsurface. The movement of brine becomes important if it travels vertically and reaches an existing or potential underground source of drinking water where an increase in salt content may threaten the viability of the drinking water source. Vertical displacement of brine may occur slowly through confining layers, or more rapidly through faults and abandoned wells. This presentation compares several (semi-) analytic solutions to determine their applicability to the problem of brine pressurization and displacement. The goal is to find ranges of formation parameters (e.g., formation seal conductivity, distance to lateral boundary, … ) for which simplifying assumption are justifiable Each simplification in the conceptual model (e.g., neglecting the lateral boundary turns a bounded domain into an infinite one) leads to a simpler (semi-) analytic solution. The process involves a solution hierarchy from the most complex solution down to the basic Theis solution. A software tool-kit implementing several (semi-) analytic solutions was developed for this study to facilitate the comparison of the solutions.

  11. Strategies for displacing oil

    NASA Astrophysics Data System (ADS)

    Rao, Vikram; Gupta, Raghubir

    2015-03-01

    Oil currently holds a monopoly on transportation fuels. Until recently biofuels were seen as the means to break this stranglehold. They will still have a part to play, but the lead role has been handed to natural gas, almost solely due to the increased availability of shale gas. The spread between oil and gas prices, unprecedented in its scale and duration, will cause a secular shift away from oil as a raw material. In the transport fuel sector, natural gas will gain traction first in the displacement of diesel fuel. Substantial innovation is occurring in the methods of producing liquid fuel from shale gas at the well site, in particular in the development of small scale distributed processes. In some cases, the financing of such small-scale plants may require new business models.

  12. Earth's Surface Displacements from the GPS Time Series

    NASA Astrophysics Data System (ADS)

    Haritonova, D.; Balodis, J.; Janpaule, I.; Morozova, K.

    2015-11-01

    The GPS observations of both Latvian permanent GNSS networks - EUPOS®-Riga and LatPos, have been collected for a period of 8 years - from 2007 to 2014. Local surface displacements have been derived from the obtained coordinate time series eliminating different impact sources. The Bernese software is used for data processing. The EUREF Permanent Network (EPN) stations in the surroundings of Latvia are selected as fiducial stations. The results have shown a positive tendency of vertical displacements in the western part of Latvia - station heights are increasing, and negative velocities are observed in the central and eastern parts. Station vertical velocities are ranging in diapason of 4 mm/year. In the case of horizontal displacements, site velocities are up to 1 mm/year and mostly oriented to the south. The comparison of the obtained results with data from the deformation model NKG_RF03vel has been made. Additionally, the purpose of this study is to analyse GPS time series obtained using two different data processing strategies: Precise Point Positioning (PPP) and estimation of station coordinates relatively to the positions of fiducial stations also known as Differential GNSS.

  13. Applying local Green's functions to study the influence of the crustal structure on hydrological loading displacements

    NASA Astrophysics Data System (ADS)

    Dill, Robert; Klemann, Volker

    2015-04-01

    The influence of the elastic Earth properties on seasonal or shorter periodic surface mass loads due to atmospheric surface pressure and terrestrial water storage variations is usually modeled by applying a local isostatic model like a homogeneous half-space model, or by a one dimensional spherical Earth model like PREM from which a unique set of elastic load Love numbers, or alternatively, elastic Green's functions are derived. The drawbacks of these strategies are that, in the first case, the response according to the local Earth structure is valid only if load and observer almost coincide, or that, in the second case, only the response of an average Earth structure is considered. However, for surface loads with horizontal scales less than 2500 km2, as for instance, for strong localized hydrological signals associated with heavy precipitation events and river floods, the Earth elastic response becomes very sensitive to inhomogeneities in the Earth crustal structure. We derive a set of local Green's functions defined for every global 1°× 1° gridcell for the 3-layer crustal structure TEA12. Local Green's functions show standard deviations of ±12% in the vertical and ±21% in the horizontal directions for distances in the range from 0.1° to 0.5°. The application of local Green's functions introduces a variability of 0.5 - 1.0 mm into the hydrological loading displacements, both in vertical and in horizontal directions. Maximum changes due to the local crustal structures are from -25% to +26% in the vertical and -91% to +55% in the horizontal displacements. In addition, the horizontal displacement changes its direction significantly, even to the opposite. The modeling of a site-dependent crustal response to surface loads provides an alternative way to probe the density and elastic structure of the Earth's crust and mantle by means of observed surface deformations caused by mass re-distributions. In addition, realistic loading models allow the monitoring of mass

  14. Oil-material fractionation in Gulf deep water horizontal intrusion layer: Field data analysis with chemodynamic fate model for Macondo 252 oil spill.

    PubMed

    Melvin, A T; Thibodeaux, L J; Parsons, A R; Overton, E; Valsaraj, K T; Nandakumar, K

    2016-04-15

    Among the discoveries of the Deepwater Horizon blowout was the so-called "sub-surface plume"; herein termed the "oil-trapping layer". Hydrocarbons were found positioned at ~1100-1300m with thickness ~100-150m and moving horizontally to the SW in a vertically stratified layer at the junction of the cold abyssal water and the permanent thermocline. This study focuses on its formation process and fate of the hydrocarbons within. The originality of this work to the field is two-fold, first it provides a conceptual framework which places layer origin in the context of a horizontal "intrusion" from the near-field, vertical, blow-out plume and second, it offers a theoretical model for the hydrocarbon chemicals within the horizontal layer as it moves far-afield. The model quantifies the oil-material fractionation process for the soluble and fine particle. The classical Box model, retrofitted with an internal gradient, the "G-Box", allows an approach that includes turbulent eddy diffusion coupled with droplet rise velocity and reactive decay to produce a simple, explicit, transparent, algebraic model with few parameters for the fate of the individual fractions. Computations show the soluble and smallest liquid droplets moving very slowly vertically through the layer appearing within the trapping layer at low concentration with high persistence. The larger droplets move-through this trapping zone quickly, attain high concentrations, and eventually form the sea surface slick. It impacts the field of oil spill engineering science by providing the conceptual idea and the algorithms for projecting the quantities and fractions of oil-material in a deep water, horizontal marine current being dispersed and moving far afield. In the field of oil spill modeling this work extends the current generation near-field plume source models to the far-field. The theory portrays the layer as an efficient oil-material trap. The model-forecasted concentration profiles for alkanes and aromatics

  15. Precision displacement reference system

    DOEpatents

    Bieg, Lothar F.; Dubois, Robert R.; Strother, Jerry D.

    2000-02-22

    A precision displacement reference system is described, which enables real time accountability over the applied displacement feedback system to precision machine tools, positioning mechanisms, motion devices, and related operations. As independent measurements of tool location is taken by a displacement feedback system, a rotating reference disk compares feedback counts with performed motion. These measurements are compared to characterize and analyze real time mechanical and control performance during operation.

  16. Some Effects of Horizontal-Tail Position on the Vertical-Tail Pressure Distributions of a Complete Model in Sideslip at High Subsonic Speeds

    NASA Technical Reports Server (NTRS)

    Alford, William J., Jr.

    1958-01-01

    An investigation has been made in the Langley high-speed 7- by 10-foot tunnel of some effects of horizontal-tail position on the vertical-tail pressure distributions of a complete model in sideslip at high subsonic speeds. The wing of the model was swept back 28.82 deg at the quarter-chord line and had an aspect ratio of 3.50, a taper ratio of 0.067, and NACA 65A004 airfoil sections parallel to the model plane of symmetry. Tests were made with the horizontal tail off, on the wing-chord plane extended, and in T-tail arrangements in forward and rearward locations. The test Mach numbers ranged from 0.60 to 0.92, which corresponds to a Reynolds number range from approximately 2.93 x 10(exp 6) to 3.69 x 10(exp 6), based on the wing mean aerodynamic chord. The sideslip angles varied from -3.9 deg to 12.7 deg at several selected angles of attack. The results indicated that, for a given angle of sideslip, increases in angle of attack caused reductions in the vertical-tail loads in the vicinity of the root chord and increases at the midspan and tip locations, with rearward movements in the local chordwise centers of pressure for the midspan locations and forward movements near the tip of the vertical tail. At the higher angles of attack all configurations investigated experienced outboard and rearward shifts in the center of pressure of the total vertical-tail load. Location of the horizontal tail on the wing- chord plane extended produced only small effects on the vertical-tail loads and centers of pressure. Locating the horizontal tail at the tip of the vertical tail in the forward position caused increases in the vertical-tail loads; this configuration, however, experienced considerable reduction in loads with increasing Mach number. Location of the horizontal tail at the tip of the vertical tail in the rearward position produced the largest increases in vertical-tail loads per degree sideslip angle; this configuration experienced the smallest variations of loads with

  17. Sensitivity of model formulation to resolution: an example focusing on the global energy budget in three atmospheric GCMs with various horizontal resolutions

    NASA Astrophysics Data System (ADS)

    Demory, Marie-Estelle; Matsueda, Mio; Vidale, Pier Luigi; Roberts, Malcolm

    2013-04-01

    Changes in the global energy budget of the Earth come from changes in the net solar radiation or in the outgoing longwave radiation and can have profound impacts on global-scale features, such as the global hydrological cycle. These fluxes strongly depend on clouds, aerosols and greenhouse gases, whose interactions with the climate system are mainly parameterised in General Circulation Models (GCM). As more and more GCMs are being developed at higher horizontal resolutions, the sensitivity of processes of the climate system to resolution are being explored, over different timescales and spatial scales. In this study, we assess the sensitivity of the simulated global annual energy budget to horizontal resolution in three different atmospheric GCMs that have a hierarchy of similar formulations with different resolutions: the UK Met Office Hadley Centre's HadGEM1-A and HadGEM3-A models, and the Japanese Meteorological Research Institute's MRI-AGCM3.2 model. We will show that, in present-day climate, the global energy budget is well simulated by the three models considered, compared to recently published estimates of the Earth's global energy budget. We will also show that the global energy budget is insensitive to horizontal resolution in both HadGEM1-A and HadGEM3-A, but is sensitive to resolution in MRI-AGCM3.2. These findings emphasise that the sensitivity of the simulated global energy budget to horizontal resolution may depend on model formulation, and we will also present primarily results on the cause of this dependency, whether it depends on tuning, on different resolution adjustments in the parameterisation schemes or on the dynamics of the models. These results show further evidence that the diversity of models' behaviour can simply depend on their resolution, a result that is well known for weather-like features (cyclones, precipitation extremes, blockings), and that this difference in behaviour can also start in the primary driver of the Earth's climate

  18. Mathematical Modeling and Microstructure Analysis of Low Carbon Steel Strips Produced by Horizontal Single Belt Casting (HSBC)

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Chang, Sheng; Wang, Tong; Calzado, Luis E.; Isac, Mihaiela; Kozinski, Janusz; Guthrie, Roderick I. L.

    2016-03-01

    The horizontal single belt casting (HSBC) process has been proposed as an efficient, economical, and environmentally friendly alternative approach to the production of ferrous alloys. Low carbon steel strips were cast using the HSBC simulator apparatus to study the characteristics and properties of the as-cast steel strips. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were also performed. Numerical predictions were validated against experimental casting results. Microstructural analyses and as-cast surface texture studies were conducted on low carbon steels.

  19. Mathematical Modeling and Microstructure Analysis of Low Carbon Steel Strips Produced by Horizontal Single Belt Casting (HSBC)

    NASA Astrophysics Data System (ADS)

    Ge, Sa; Chang, Sheng; Wang, Tong; Calzado, Luis E.; Isac, Mihaiela; Kozinski, Janusz; Guthrie, Roderick I. L.

    2016-06-01

    The horizontal single belt casting (HSBC) process has been proposed as an efficient, economical, and environmentally friendly alternative approach to the production of ferrous alloys. Low carbon steel strips were cast using the HSBC simulator apparatus to study the characteristics and properties of the as-cast steel strips. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were also performed. Numerical predictions were validated against experimental casting results. Microstructural analyses and as-cast surface texture studies were conducted on low carbon steels.

  20. DISPLACEMENT BASED SEISMIC DESIGN METHODS.

    SciTech Connect

    HOFMAYER,C.MILLER,C.WANG,Y.COSTELLO,J.

    2003-07-15

    A research effort was undertaken to determine the need for any changes to USNRC's seismic regulatory practice to reflect the move, in the earthquake engineering community, toward using expected displacement rather than force (or stress) as the basis for assessing design adequacy. The research explored the extent to which displacement based seismic design methods, such as given in FEMA 273, could be useful for reviewing nuclear power stations. Two structures common to nuclear power plants were chosen to compare the results of the analysis models used. The first structure is a four-story frame structure with shear walls providing the primary lateral load system, referred herein as the shear wall model. The second structure is the turbine building of the Diablo Canyon nuclear power plant. The models were analyzed using both displacement based (pushover) analysis and nonlinear dynamic analysis. In addition, for the shear wall model an elastic analysis with ductility factors applied was also performed. The objectives of the work were to compare the results between the analyses, and to develop insights regarding the work that would be needed before the displacement based analysis methodology could be considered applicable to facilities licensed by the NRC. A summary of the research results, which were published in NUREGICR-6719 in July 2001, is presented in this paper.

  1. Inter-generational micro-class mobility during and after socialism: The power, education, autonomy, capital, and horizontal (PEACH) model in Hungary.

    PubMed

    Lippényi, Zoltán; Gerber, Theodore P

    2016-07-01

    We propose a theoretical model of how occupational mobility operates differently under socialism than under market regimes. Our model specifies four vertical dimensions of occupational resources-power, education, autonomy, and capital-plus a horizontal dimension consisting of linkages among occupations in the same economic branch. Given the nature of state socialist political-economic institutions, we expect power to exhibit much stronger effects in the socialist mobility regime, while autonomy and capital should play greater stratifying roles after the market transition. Education should have stable effects, and horizontal linkages should diminish in strength with market reforms. We estimate our model's parameters using data from surveys conducted in Hungary during and after the socialist period. We adopt a micro-class approach, though we test it against approaches that use more aggregated class categories. Our model provides a superior fit to other mobility models, and our results confirm our hypotheses about the distinctive features of the state socialist mobility regime. Mobility researchers often look for common patterns characterizing mobility in all industrialized societies. Our findings suggest that national institutions can produce fundamentally distinct patterns of mobility. PMID:27194653

  2. Characteristics of capacitance-micro-displacement for model of complex interior surface of the 3D Taiji ball and its applications

    NASA Astrophysics Data System (ADS)

    Zhu, Ruo-Gu; Jiang, Kun; Qing, Zhao-Bo; Liu, Yue-Hui; Yan, Jun

    2006-11-01

    Taiji image originated from ancient China. It is not only the Taoism emblem but also the ancient graphic presentation sign to everything origin. It either has a too far-reaching impact on traditional culture of China, or is influencing the development of current natural science. On the basis of analyzing the classical philosophic theory of two-dimensional (2-D) Taiji image, we developed it into the model of complex interior surface-three-dimensional (3-D) Taiji ball, and explored its possible applications. Combining modern mathematics and physics knowledge, we have studied on the physical meaning of 3-D Taiji ball, thus the plane change of original Taiji image is developed into space change which is more close to the real world. The change layers are obvious increased notably, and the amount of information included in this model increases correspondingly. We also realized a special paper 3-D Taiji ball whose surface is coved with metal foil by means of laser manufacture. A new experiment set-up for measuring micro displace has been designed and constituted thus the relation between capacitance and micro displacement for the 3-D Taiji ball has performed. Experimental and theoretical analyses are also finished. This models of 3-D Taiji ball for physical characteristics are the first time set up. Experimental data and fitting curves between capacitance and micro displacement for the special paper Taiji ball coved with metal foil are suggested. It is shown that the special Taiji ball has less leakage capacitance or more strengthen electric field than an ordinary half ball capacitance. Finally their potential applied values are explored.

  3. Assessment of longwall-roof behavior and support loading by linear elastic modeling of the support structure. Report of Investigations/1987

    SciTech Connect

    Barczak, T.M.; Burton, W.S.

    1987-01-01

    Longwall-roof behavior is characterized by strata displacements in both the face-to-waste (horizontal) and roof-to-floor (vertical) directions. The roof-support structure provides resistance to this motion by translation of these displacements into vertical and horizontal support loading. Observations indicate that the shield reacts with both a vertical and horizontal force to uniaxial convergence (displacement). However, there are different magnitudes depending on whether the displacement is vertical or horizontal. This makes it possible to use supports as monitors of strata activity and loading. The Bureau of Mines examined this behavior using a linear elastic model of the support structure with two degrees of freedom. Vertical and horizontal load reactions were related to associated displacement actions of the strata. This was done by determining the stiffness of the shield under controlled vertical and horizontal displacement motions in the Bureau's mine roof simulator. The report provides example predictions of strata convergence and isolation of horizontal support loading due to vertical roof convergence using the linear elastic shield model. The report also examines efforts to determine strata behavior by direct measurement of support displacement.

  4. Origin, distribution, and movement of brine in the Permian Basin (U. S. A. ). A model for displacement of connate brine

    SciTech Connect

    Bein, A.; Dutton, A.R. )

    1993-06-01

    Na-Cl, halite Ca-Cl, and gypsum Ca-Cl brines with salinities from 45 to >300 g/L are identified and mapped in four hydrostratigraphic units in the Permian Basin area beneath western Texas and Oklahoma and eastern New Mexico, providing spatial and lithologic constraints on the interpretation of the origin and movement of brine. Na-Cl brine is derived from meteoric water as young as 5-10 Ma that dissolved anhydrite and halite, whereas Ca-Cl brine is interpreted to be ancient, modified-connate Permian brine that now is mixing with, and being displaced by, the Na-Cl brine. Displacement fronts appear as broad mixing zones with no significant salinity gradients. Evolution of Ca-Cl brine composition from ideal evaporated sea water is attributed to dolomitization and syndepositional recycling of halite and bittern salts by intermittent influx of fresh water and sea water. Halite Ca-Cl brine in the evaporite section in the northern part of the basin differs from gypsum Ca-Cl brine in the south-central part in salinity and Na/Cl ratio and reflects segregation between halite- and gypsum-precipitating lagoons during the Permian. Ca-Cl brine moved downward through the evaporite section into the underlying Lower Permian and Pennsylvanian marine section that is now the deep-basin brine aquifer, mixing there with pre-existing sea water. Buoyancy-driven convection of brine dominated local flow for most of basin history, with regional advection governed by topographically related forces dominant only for the past 5 to 10 Ma. 71 refs., 11 figs.

  5. Crustal Displacements Due to Continental Water Loading

    NASA Technical Reports Server (NTRS)

    vanDam, T.; Wahr, J.; Milly, P. C. D.; Shmakin, A. B.; Blewitt, G.; Lavallee, D.; Larson, K. M.

    2001-01-01

    The effects of long-wavelength (> 100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (delta-r(sub M)) have root-mean-square (RMS) values for 1994-1998 as large as 8 mm with ranges up to 30 mm, and are predominantly annual in character. Regional strains are on the order of 20 nanostrain for tilt and 5 nanostrain for horizontal deformation. We compare delta-r(sub M) with observed Global Positioning System (GPS) heights (delta-r(sub O)) (which include adjustments to remove estimated effects of atmospheric pressure and annual tidal and non-tidal ocean loading) for 147 globally distributed sites. When the delta-r(sub O) time series are adjusted by delta-r(sub M), their variances are reduced, on average, by an amount equal to the variance of the delta-r(sub M). Of the delta-r(sub O) time series exhibiting a strong annual signal, more than half are found to have an annual harmonic that is in phase and of comparable amplitude with the annual harmonic in the delta-r(sub M). The delta-r(sub M) time series exhibit long-period variations that could be mistaken for secular tectonic trends or post-glacial rebound when observed over a time span of a few years.

  6. Crustal displacements due to continental water loading

    USGS Publications Warehouse

    Van Dam, T.; Wahr, J.; Milly, P.C.D.; Shmakin, A.B.; Blewitt, G.; Lavallee, D.; Larson, K.M.

    2001-01-01

    The effects of long-wavelength (> 100 km), seasonal variability in continental water storage on vertical crustal motions are assessed. The modeled vertical displacements (??rM) have root-mean-square (RMS) values for 1994-1998 as large as 8 mm, with ranges up to 30 mm, and are predominantly annual in character. Regional strains are on the order of 20 nanostrain for tilt and 5 nanostrain for horizontal deformation. We compare ??rM with observed Global Positioning System (GPS) heights (??rO) (which include adjustments to remove estimated effects of atmospheric pressure and annual tidal and non-tidal ocean loading) for 147 globally distributed sites. When the ??rO time series are adjusted by ??rM, their variances are reduced, on average, by an amount equal to the variance of the ??rM. Of the ??rO time series exhibiting a strong annual signal, more than half are found to have an annual harmonic that is in phase and of comparable amplitude with the annual harmonic in the ??rM. The ??rM time series exhibit long-period variations that could be mistaken for secular tectonic trends or post-glacial rebound when observed over a time span of a few years.

  7. A simple model for testing the effects of gravity-wave-produced vertical oscillations of scattering irregularities on spaced-antenna, horizontal drift measurements

    NASA Technical Reports Server (NTRS)

    Meek, C. E.; Reid, I. M.

    1984-01-01

    It has been suggested that the velocities produced by the spaced antenna partial-reflection drift experiment may constitute a measure of the vertical oscillations due to short-period gravity waves rather than the mean horizontal flow. The contention is that the interference between say two scatterers, one of which is traveling upward, and the other down, will create a pattern which sweeps across the ground in the direction (or anti-parallel) of the wave propagation. Since the expected result, viz., spurious drift directions, is seldom, if ever, seen in spaced antenna drift velocities, this speculation is tested in an atmospheric model.

  8. New tools allow medium-radius horizontal drilling

    SciTech Connect

    Dech, J.A.; Hearn, D.D.; Schuh, F.J.; Lenhart, B.

    1986-07-14

    ARCO Oil and Gas Co. (AOGC) recently completed a project to develop new methods of drilling conventional-sized horizontal holes. A well bore of this type is particularly well-suited for producing low-permeability, fractured reservoirs at economic rates. Special drilling tools and support equipment were developed jointly with several major manufacturers. Of these tools, one of the systems developed with Norton Christensen most nearly met the design goals. This system was tested in Rockwall County, Tex., where a 6-in. OD horizontal hole was successfully drilled in the Austin chalk formation. The build rate from vertical to horizontal was 20/sup 0//100 ft; the horizontal portion of the well bore was drilled for another 1,340 ft. This gave a total horizontal displacement of 1,630 ft. The horizontal well bore was kept within a 30-ft vertical section.

  9. Development and Verification of a Computational Fluid Dynamics Model of a Horizontal-Axis Tidal Current Turbine

    SciTech Connect

    Lawson, M. J.; Li, Y.; Sale, D. C.

    2011-10-01

    This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.

  10. Ellipsoidal Harmonic Vertical Deflections. Global and Regional Modeling of The Horizontal Derivative of The Terrestrial Garvity Field

    NASA Astrophysics Data System (ADS)

    Grafarend, E. W.; Ardalan, A.; Finn, G.

    In terms of elliptic coordinates of Jacobi type (longitude, latitude, semi-minor axis) the horizontal derivative is computed as a linear operator acting on an ellipsoidal har- monic disturbing/incremental gravitational potential. Such disturbing potential is de- fined with respect to the Somigliana-Pizzetti Reference Potential, the potential field of a level ellipsoid, and the International Reference Ellipsoid/WGS84 or World Geode- tic Datum 2000/WGD2000. Case studies of those vertical deflections on a global as well as regional scale are presented which take advantage of SEGEN (Special Ellipsoidal Gravity Earth Normal: ellipsoidal harmonics expansion 130321 coeffi- cients: http://www.uni-stuttgart.de/gi/research/paper/coefficients/coefficients.zip) and of CENT (precise centrifugal potential)

  11. Sheared sheet intrusions as a mechanism for lateral flank displacement on basaltic volcanoes: Applications to Réunion Island volcanoes

    NASA Astrophysics Data System (ADS)

    Cayol, V.; Catry, T.; Michon, L.; Chaput, M.; Famin, V.; Bodart, O.; Froger, J. L.; Romagnoli, C.

    2014-12-01

    Field work carried out on the Piton des Neiges volcano (Réunion Island) suggests that the injection of magma along detachments could trigger flank failure by conjugate opening and shear displacement [Famin and Michon, 2010]. We use 3D numerical models to compare the ability of purely opened sheet intrusions, sheared sheet intrusions, and normal faults to induce flank displacement on basaltic volcanoes (Figure). We assume that shear stress change on fractures which are not normal to a principal stress results from stress anisotropy of the host rock under gravity. Exploring a large range of stress anisotropies, fracture dips, and fracture depth over length ratios, we determine that the amount of shear displacement is independent of the proximity to the ground surface. Sheared sheet intrusions are the most efficient slip medium on volcanoes. Using our model in a forward way, we provide shear and normal displacements for buried fractures. Applying the model to a pile of sills at the Piton des Neiges volcano, we determine that the mean shear displacement caused by each intrusion was 3.7 m, leading to a total of a 180-260 m of lateral displacement for the 50 m high pile of sills. Using our model in an inverse way, we formulate a decision tree to determine some fracture characteristics and the host rock stress anisotropy from ratios of maximum surface displacements. This procedure provides a priori models, thus limits to the parameter space which can be further explored through a formal inversion. Applying this procedure to the 1.4 m co-eruptive flank displacement recorded at Piton de la Fournaise in 2007, we find that it probably originated from a shallow eastward-dipping sub-horizontal normal fault.

  12. Regional subsidence modelling in Murcia city (SE Spain) using 1-D vertical finite element analysis and 2-D interpolation of ground surface displacements

    NASA Astrophysics Data System (ADS)

    Tessitore, S.; Fernández-Merodo, J. A.; Herrera, G.; Tomás, R.; Ramondini, M.; Sanabria, M.; Duro, J.; Mulas, J.; Calcaterra, D.

    2015-11-01

    Subsidence is a hazard that may have natural or anthropogenic origin causing important economic losses. The area of Murcia city (SE Spain) has been affected by subsidence due to groundwater overexploitation since the year 1992. The main observed historical piezometric level declines occurred in the periods 1982-1984, 1992-1995 and 2004-2008 and showed a close correlation with the temporal evolution of ground displacements. Since 2008, the pressure recovery in the aquifer has led to an uplift of the ground surface that has been detected by the extensometers. In the present work an elastic hydro-mechanical finite element code has been used to compute the subsidence time series for 24 geotechnical boreholes, prescribing the measured groundwater table evolution. The achieved results have been compared with the displacements estimated through an advanced DInSAR technique and measured by the extensometers. These spatio-temporal comparisons have showed that, in spite of the limited geomechanical data available, the model has turned out to satisfactorily reproduce the subsidence phenomenon affecting Murcia City. The model will allow the prediction of future induced deformations and the consequences of any piezometric level variation in the study area.

  13. Polymorphism of iron at high pressure: A 3D phase-field model for displacive transitions with finite elastoplastic deformations

    NASA Astrophysics Data System (ADS)

    Vattré, A.; Denoual, C.

    2016-07-01

    A thermodynamically consistent framework for combining nonlinear elastoplasticity and multivariant phase-field theory is formulated at large strains. In accordance with the Clausius-Duhem inequality, the Helmholtz free energy and time-dependent constitutive relations give rise to displacive driving forces for pressure-induced martensitic phase transitions in materials. Inelastic forces are obtained by using a representation of the energy landscape that involves the concept of reaction pathways with respect to the point group symmetry operations of crystal lattices. On the other hand, additional elastic forces are derived for the most general case of large strains and rotations, as well as nonlinear, anisotropic, and different elastic pressure-dependent properties of phases. The phase-field formalism coupled with finite elastoplastic deformations is implemented into a three-dimensional Lagrangian finite element approach and is applied to analyze the iron body-centered cubic (α-Fe) into hexagonal close-packed (ɛ-Fe) phase transitions under high hydrostatic compression. The simulations exhibit the major role played by the plastic deformation in the morphological and microstructure evolution processes. Due to the strong long-range elastic interactions between variants without plasticity, a forward α → ɛ transition is energetically unfavorable and remains incomplete. However, plastic dissipation releases considerably the stored strain energy, leading to the α ↔ ɛ ↔α‧ (forward and reverse) polymorphic phase transformations with an unexpected selection of variants.

  14. A DLVO model for catalyst motion in metal-assisted chemical etching based upon controlled out-of-plane rotational etching and force-displacement measurements

    NASA Astrophysics Data System (ADS)

    Hildreth, Owen J.; Rykaczewski, Konrad; Fedorov, Andrei G.; Wong, Ching P.

    2013-01-01

    Metal-assisted Chemical Etching of silicon has recently emerged as a powerful technique to fabricate 1D, 2D, and 3D nanostructures in silicon with high feature fidelity. This work demonstrates that out-of-plane rotational catalysts utilizing polymer pinning structures can be designed with excellent control over rotation angle. A plastic deformation model was developed establishing that the catalyst is driven into the silicon substrate with a minimum pressure differential across the catalyst thickness of 0.4-0.6 MPa. Force-displacement curves were gathered between an Au tip and Si or SiO2 substrates under acidic conditions to show that Derjaguin and Landau, Verwey and Overbeek (DLVO) based forces are capable of providing restorative forces on the order of 0.2-0.3 nN with a calculated 11-18 MPa pressure differential across the catalyst. This work illustrates that out-of-plane rotational structures can be designed with controllable rotation and also suggests a new model for the driving force for catalyst motion based on DLVO theory. This process enables the facile fabrication of vertically aligned thin-film metallic structures and scalloped nanostructures in silicon for applications in 3D micro/nano-electromechanical systems, photonic devices, nanofluidics, etc.Metal-assisted Chemical Etching of silicon has recently emerged as a powerful technique to fabricate 1D, 2D, and 3D nanostructures in silicon with high feature fidelity. This work demonstrates that out-of-plane rotational catalysts utilizing polymer pinning structures can be designed with excellent control over rotation angle. A plastic deformation model was developed establishing that the catalyst is driven into the silicon substrate with a minimum pressure differential across the catalyst thickness of 0.4-0.6 MPa. Force-displacement curves were gathered between an Au tip and Si or SiO2 substrates under acidic conditions to show that Derjaguin and Landau, Verwey and Overbeek (DLVO) based forces are capable of

  15. Impact of increased horizontal resolution in coupled and atmosphere-only models of the HadGEM1 family upon the climate patterns of South America

    NASA Astrophysics Data System (ADS)

    de Souza Custodio, Maria; da Rocha, Rosmeri Porfírio; Ambrizzi, Tércio; Vidale, Pier Luigi; Demory, Marie-Estelle

    2016-07-01

    This study investigates the impact of increased horizontal resolution in coupled and atmosphere-only global climate models on the simulation of climate patterns in South America (SA). We analyze simulations of the HadGEM1 model family with three different horizontal resolutions in the atmosphere—N96 (~135 km at 50°N), N144 (~90 km) and N216 (~60 km)—and two different resolutions in the ocean—1° and 1/3°. In general, the coupled simulation with the highest resolution (60 km in the atmosphere and 1/3° in the ocean) has smaller systematic errors in seasonal mean precipitation, temperature and circulation over SA than the atmosphere-only model at all resolutions. The models, both coupled and atmosphere-only, properly simulate spatial patterns of the seasonal shift of the Intertropical Convergence Zone (ITCZ), the formation and positioning of the South Atlantic Convergence Zone (SACZ), and the subtropical Atlantic and Pacific highs. However, the models overestimate rainfall, especially in the ITCZ and over the western border of high-elevation areas such as southern Chile. The coupling, combined with higher resolution, result in a more realistic spatial pattern of rain, particularly over the Atlantic ITCZ and the continental branch of the SACZ. All models correctly simulate the phase and amplitude of the annual cycle of precipitation and air temperature over most of South America. The overall results show that despite some problems, increasing the resolution in the HadGEM1 model family results in a more realistic representation of climate patterns over South America and the adjacent oceans.

  16. Efficient and automatic calculation of optical band shapes and resonance Raman spectra for larger molecules within the independent mode displaced harmonic oscillator model.

    PubMed

    Petrenko, Taras; Neese, Frank

    2012-12-21

    In this work, an improved method for the efficient automatic simulation of optical band shapes and resonance Raman (rR) intensities within the "independent mode displaced harmonic oscillator" is described. Despite the relative simplicity of this model, it is able to account for the intensity distribution in absorption (ABS), fluorescence, and rR spectra corresponding to strongly dipole allowed electronic transitions with high accuracy. In order to include temperature-induced effects, we propose a simple extension of the time dependent wavepacket formalism developed by Heller which enables one to derive analytical expressions for the intensities of hot bands in ABS and rR spectra from the dependence of the wavepacket evolution on its initial coordinate. We have also greatly optimized the computational procedures for numerical integration of complicated oscillating integrals. This is important for efficient simulations of higher-order rR spectra and excitation profiles, as well as for the fitting of experimental spectra of large molecules. In particular, the multimode damping mechanism is taken into account for efficient reduction of the upper time limit in the numerical integration. Excited state energy gradient as well as excited state geometry optimization calculations are employed in order to determine excited state dimensionless normal coordinate displacements. The gradient techniques are highly cost-effective provided that analytical excited state derivatives with respect to nuclear displacements are available. Through comparison with experimental spectra of some representative molecules, we illustrate that the gradient techniques can even outperform the geometry optimization method if the harmonic approximation becomes inadequate. PMID:23267471

  17. Independent feedback control of horizontal and vertical amplitude during oblique saccades evoked by electrical stimulation of the superior colliculus.

    PubMed

    Nichols, M J; Sparks, D L

    1996-12-01

    1. In early local feedback models for controlling horizontal saccade amplitude, a feedback signal of instantaneous eye position is continuously subtracted from a reference signal of desired eye position at a comparator. The output of the comparator is dynamic motor error, the remaining distance the eyes must rotate to reach the saccadic goal. When feedback reduces dynamic motor error to zero, the saccade stops on target. Two classes of local feedback model have been proposed for controlling oblique saccades (i.e., saccades with both horizontal and vertical components). In "independent comparator" models, separate horizontal and vertical comparators maintain independent representations of horizontal and vertical dynamic motor error. Thus, once an oblique desired displacement signal is established, the horizontal and vertical amplitudes of oblique saccades are under independent feedback control. In "vectorial comparator" models, output cells in the motor map of the superior colliculus act as site-specific vectorial comparators. For a given oblique desired displacement, a single comparator controls the amplitudes of both components. Because vectorial comparator models do not maintain separate representations of horizontal and vertical dynamic motor error, they cannot exert independent control over the component amplitudes of oblique saccades. 2. We tested differential predictions of these two types of models by electrically stimulating sites in the superior colliculus of rhesus monkey immediately after either vertical or horizontal visually guided saccades. We have shown previously that, despite the fixed site of collicular stimulation, the amplitude of the visually guided saccades systematically alters the amplitude of the corresponding component (horizontal or vertical) of stimulation-evoked saccades. However, in the present study, we examined the effect of the visually guided saccades on the amplitude of the orthogonal component of stimulation-evoked saccades. 3

  18. Optical measuring displacement transducers

    NASA Astrophysics Data System (ADS)

    Dich, L. Z.

    1994-09-01

    Trends in the development and production of photoelectric displacement transducers are analyzed. The technical characteristics of certain transducers are briefly presented. A table of comparisons is given, based on available information sources.

  19. A comparison of wind turbulence simulation models for stochastic loads analysis for horizontal-axis wind turbines

    NASA Astrophysics Data System (ADS)

    Walker, S. N.; Weber, T. L.; Wilson, R. E.

    1989-06-01

    Four wind turbine turbulence codes, the Pacific Northwest Laboratory (PNL) Rotational Code, the PNL Simulation Code, the Holley Code, and the Sandia National Laboratories Code, were examined. Hub-height simulations were made with each code and were compared to hub-height wind data from the vertical plane array of anemometers at the Howden 330-kW horizontal-axis wind turbine (HAWT). Blade tip simulations were made with each code and were compared to rotational wind data taken from the Howden-330 kW HAWT. The PNL Rotational Code was given an overall rating of satisfactory for large wind turbine applications and an overall rating of good for small wind turbine applications. The PNL Simulation Code was given a rating of good when used with large turbines and a rating of very good when used with small turbines. The Holley Code and the Sandia Code were given ratings of good and satisfactory, respectively, for both large and small wind turbine applications. The Sandia Code could be upgraded if documentation were made available. Further upgrades for any of the codes would require major revision.

  20. Development and Verification of a Computational Fluid Dynamics Model of a Horizontal-Axis Tidal Current Turbine

    SciTech Connect

    Lawson, Mi. J.; Li, Y.; Sale, D. C.

    2011-01-01

    This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines (HATTs). First, an HATT blade was designed using the blade element momentum method in conjunction with a genetic optimization algorithm. Several unstructured computational grids were generated using this blade geometry and steady CFD simulations were used to perform a grid resolution study. Transient simulations were then performed to determine the effect of time-dependent flow phenomena and the size of the computational timestep on the numerical solution. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.

  1. Our Experience with Left-Sided Abomasal Displacement Correction via the Roll-and-Toggle-Pin Suture Procedure according to Grymer/Sterner Model

    PubMed Central

    Zadnik, T.; Lombar, R.

    2011-01-01

    All over the world, and also in Slovenia, left-sided displacement of the abomasum (LDA) occurs most commonly in large-sized, high-producing adult dairy cows immediately after parturition. Yearly retrospective analyses of our ambulatory records showed significantly increased prevalence of LDA (2000 = 0.9%, 2010 = 3.7%), especially in cows after first parturition. Surgical replacement is now commonly practiced, and many techniques have been devised with emphasis on avoidance of recurrence of the displacement. Because of good results as recorded in the literature and encouragement of Keith E. Sterner, the author of this method, we want to try the right paramedian abomasopexy—Grymer/Sterner model. Since May 2009 till October 2011 109 cows from 46 farms were operated on because of LDA. As many as 44 (40.3%) were affected with LDA after first parturition. The analysis of successful procedure that was carried out 2 months after suture showed that 104 (95.4%) cows were cured. Only 5 (4.5%) cows died within 24 hours after surgery (4 cases of severe toxemia with hypokalemia and one case of acute abomasal hemorrhage were established). Our experience with Grymer/Sterner LDA transfixation sutures proved favorable. Because roll-and-toggle-pin suture technique is rapid and inexpensive we recommend it. PMID:23738100

  2. Internal displacement in Burma.

    PubMed

    Lanjouw, S; Mortimer, G; Bamforth, V

    2000-09-01

    The internal displacement of populations in Burma is not a new phenomenon. Displacement is caused by numerous factors. Not all of it is due to outright violence, but much is a consequence of misguided social and economic development initiatives. Efforts to consolidate the state by assimilating populations in government-controlled areas by military authorities on the one hand, while brokering cease-fires with non-state actors on the other, has uprooted civilian populations throughout the country. Very few areas in which internally displaced persons (IDPs) are found are not facing social turmoil within a climate of impunity. Humanitarian access to IDP populations remains extremely problematic. While relatively little information has been collected, assistance has been focused on targeting accessible groups. International concern within Burma has couched the problems of displacement within general development modalities, while international attention along its borders has sought to contain displacement. With the exception of several recent initiatives, few approaches have gone beyond assistance and engaged in the prevention or protection of the displaced. PMID:11026156

  3. Horizontal well planning

    SciTech Connect

    Schuh, F.J. )

    1991-03-01

    Interest in horizontal drilling has exploded at a rate well above even the most optimistic projections. Certainly, this technique will not end with the Bakken and Austin Chalk plays. However, future reservoirs will undoubtedly require much more complicated well designs and multi-disciplined technical interaction than has been used so far. The horizontal drilling costs are too high to permit resolving of all the technical issues by trial and error. A multi-disciplinary team approach will be required in order for horizontal drilling to achieve its economic potential.

  4. Deformation and displacement of the Jura cover on its basement

    NASA Astrophysics Data System (ADS)

    Mugnier, J. L.; Vialon, P.

    The sedimentary cover of the Internal Jura, displaced over its basement, conforms well with the model of a thin-skinned thrust sheet. The wedge-shaped sheet, which includes a thick sequence of molasse deposited ahead of the Alpine front, slid over the basement/cover interface. The Alpine crustal thrust sheets created a load at the south-east end of the overthrust European plate. Molasse was deposited on the bent plate, and the internal part of the basin was progressively affected by thrusting. This process also induced deformation and displacements in the foreland: gravity spreading in the internal molasse, and a forward motion by rigid slipping. Movement led to a horizontal push, causing deformation by indentation in the Internal Jura. In the plateaux of the External Jura, there is very little extension in the cover and minimal shortening in the basement. This shortening induced a décollement under the plateaux. Over the Bresse graben, gravity sliding occurred in the form of huge landslides. These contrasts in the origin of the Jura structures, along a median cross-section from Thonon to Arbois, are shown by geophysical data, construction of a balanced cross-section and calculations of realistic mechanical models for the bending of the foreland plate and for the motion of the cover sheet.

  5. Wind-Tunnel Investigation of Effects of Unsymmetrical Horizontal-Tail Arrangements on Power-on Static Longitudinal Stability of a Single-Engine Airplane Model

    NASA Technical Reports Server (NTRS)

    Purser, Paul E.; Spear, Margaret F.

    1947-01-01

    A wind-tunnel investigation has been made to determine the effects of unsymmetrical horizontal-tail arrangements on the power-on static longitudinal stability of a single-engine single-rotation airplane model. Although the tests and analyses showed that extreme asymmetry in the horizontal tail indicated a reduction in power effects on longitudinal stability for single-engine single-rotation airplanes, the particular "practical" arrangement tested did not show marked improvement. Differences in average downwash between the normal tail arrangement and various other tail arrangements estimated from computed values of propeller-slipstream rotation agreed with values estimated from pitching-moment test data for the flaps-up condition (low thrust and torque) and disagreed for the flaps-down condition (high thrust and torque). This disagreement indicated the necessity for continued research to determine the characteristics of the slip-stream behind various propeller-fuselage-wing combinations. Out-of-trim lateral forces and moments of the unsymmetrical tail arrangements that were best from consideration of longitudinal stability were no greater than those of the normal tail arrangement.

  6. An evaluation of displacement-based finite element models used for free vibration analysis of homogeneous and composite plates

    NASA Astrophysics Data System (ADS)

    Burlayenko, V. N.; Altenbach, H.; Sadowski, T.

    2015-12-01

    The finite element vibration analysis of plates has become one of the classical problems over the past several decades. Different finite element plate models based on classical, standard and improved shear deformable plate theories, three-dimensional elasticity equations or their combinations have been developed. The ability and accuracy of each such model can be established by validating it against analytical models, if it is possible, or other numerical models. In this paper, a comparative study of different plate finite element models used for the free vibration analysis of homogeneous isotropic and anisotropic, composite laminated and sandwich thin and thick plates with different boundary conditions is presented. The aim of the study is to find out the weaknesses and strengths of each model used and to pick out their interchangeability for the finite element calculations. For comparisons, the plate models based on classical and first-order shear deformation theories within the framework of both single-layer and layer-wise concept and three-dimensional theory of elasticity are used. The models are created using the finite element package ABAQUSTM. Natural frequencies obtained by the authors are compared with results known in the literature from different analytical or approximate solutions and, then, the correlation between them is discussed in detail. At the end, conclusions are drawn concerning the utility of each model considered for vibration predictions of plates.

  7. Effects of Fault Displacement on Emplacement Drifts

    SciTech Connect

    F. Duan

    2000-04-25

    The purpose of this analysis is to evaluate potential effects of fault displacement on emplacement drifts, including drip shields and waste packages emplaced in emplacement drifts. The output from this analysis not only provides data for the evaluation of long-term drift stability but also supports the Engineered Barrier System (EBS) process model report (PMR) and Disruptive Events Report currently under development. The primary scope of this analysis includes (1) examining fault displacement effects in terms of induced stresses and displacements in the rock mass surrounding an emplacement drift and (2 ) predicting fault displacement effects on the drip shield and waste package. The magnitude of the fault displacement analyzed in this analysis bounds the mean fault displacement corresponding to an annual frequency of exceedance of 10{sup -5} adopted for the preclosure period of the repository and also supports the postclosure performance assessment. This analysis is performed following the development plan prepared for analyzing effects of fault displacement on emplacement drifts (CRWMS M&O 2000). The analysis will begin with the identification and preparation of requirements, criteria, and inputs. A literature survey on accommodating fault displacements encountered in underground structures such as buried oil and gas pipelines will be conducted. For a given fault displacement, the least favorable scenario in term of the spatial relation of a fault to an emplacement drift is chosen, and the analysis is then performed analytically. Based on the analysis results, conclusions are made regarding the effects and consequences of fault displacement on emplacement drifts. Specifically, the analysis will discuss loads which can be induced by fault displacement on emplacement drifts, drip shield and/or waste packages during the time period of postclosure.

  8. The role of horizontal impulses of the faulting continental slope in generating the 26 December 2004 tsunami

    NASA Astrophysics Data System (ADS)

    Song, Y. Tony; Fu, L.-L.; Zlotnicki, Victor; Ji, Chen; Hjorleifsdottir, Vala; Shum, C. K.; Yi, Yuchan

    For a long time, people have believed that the vertical displacement of seafloor due to undersea earthquakes is the primary cause of tsunami genesis. However, seismically-inverted seafloor deformation of the 2004 Sumatra-Andaman earthquake shows that the total vertical displacement is not enough to have generated the powerful Indian Ocean tsunami. Based on the seismically-inverted data and a three-dimensional ocean general circulation model (OGCM), we show that the momentum force, transferred by the horizontal impulses of the faulting continental slope in that earthquake, has accounted for two thirds of the satellite-observed tsunami height and generated kinetic energy 5 times larger than the potential energy due to the vertical displacement. The asymmetric tsunami pattern, recorded by tide-gauges showing leading-elevation waves toward Sri Lanka and leading-depression waves toward Thailand, is best explained by the horizontally-forced mechanism. The same mechanism has also explained the March 2005 Nias earthquake and tsunami data, suggesting that the horizontal motions of faulting have played more important roles in tsunami genesis than previously thought.

  9. The role of heat source area on the transition from displacement to mixing flow in natural ventilation

    NASA Astrophysics Data System (ADS)

    Kaye, Nigel; Hunt, Gary

    2007-11-01

    We present a theoretical model for the role of heat source area on the transition from displacement to mixing flow for a naturally ventilated room. We examine the relationship between the existing standard models for natural ventilation of a room with floor and ceiling level vents (Linden et al. 1990 and Gladstone & Woods 2001). We show that the uniform heat distribution model of Gladstone & Woods is the limit of an infinite number of localized heat sources based on the Linden et al. model. We then examine the transition from localized to distributed heat source behaviour as a function of the horizontal extent of the heat source. Our model is based on recent measurements of the plume flow above large area heat sources that suggests the flow rate increases linearly with height. The flow transition is a function of the room vent area scaled on the ceiling height squared and the ratio of the ceiling height to heat source radius. As the heat source radius increases there is a rapid transition from displacement ventilation, driven by localized heat sources, toward mixing ventilation, driven by distributed heat sources. This transition is independent of the floor area of the room implying that for displacement ventilation to be established the heat source(s) need to be small compared to the vertical, as well as horizontal scale of the room.

  10. Horizontal-branch stellar evolution

    NASA Technical Reports Server (NTRS)

    Sweigart, Allen V.

    1990-01-01

    The results of canonical theory for the evolution of horizontal-branch (HB) stars are examined. Particular attention is given to how an HB star maintains the appropriate composition distribution within the semiconvective zone and how this composition is affected by the finite time-dependence with which convective boundaries actually move. Newly developed models based on time-dependent overshooting are presented for both the core-helium-exhaustion and main HB phases.

  11. The Effect of Horizontal Advection of Topography and Time Dependent Crustal Deformation on Tsunami Generation

    NASA Astrophysics Data System (ADS)

    Barak, S.; Beroza, G. C.

    2013-12-01

    Initial conditions used in tsunami modeling are commonly simplified due to lack of observations, poor understanding of the mechanics of tsunami generation, and limitations on computational power and processing time. First, since the time-varying deformation of the seafloor has a negligible effect far from the source, often, only the static, or the residual deformation is used to excite the tsunami model. However, when the earthquake occurs close to the coast, the dynamic displacement of the seafloor might have a significant effect on coastal wave height and arrival time. Second, it is common to use only the vertical component of the seafloor displacement, while neglecting the horizontal co-seismic displacements in the absence of landslides. While this assumption is valid for a flat or shallowly-dipping seafloor, it has been shown that in certain conditions, such as the combination of a shallow-dipping thrust fault with relatively steep topography, the contribution of the horizontal displacement is significant and might help explain discrepancies in wave height predictions. In this study we are using the abundant observations recorded during the 2011 Tohoku-Oki earthquake and tsunami to study the effects of time-varying deformation and the contribution of horizontal seafloor displacement on tsunami generation. We use SPECFEM3D, a spectral element numerical code, to solve the elasto-dynamic problem including wave propagation and the residual static deformation, to determine the time-dependent seafloor deformation. To simulate the earthquake we use a kinematic rupture model, in which the fault slip (magnitude and direction) is determined at each point in space and time for the assumed fault geometry. In order to test the contribution of topography we run the simulation with and without the surface topography and compare the results. In addition, we compare our results to real observations, where they are available, to validate of our model. Finally, our next step will

  12. Dartmouth Stellar Evolution Database and the ACS Survey of Galactic Globular Clusters II. Stellar Evolution Tracks, Isochrones, Luminosity Functions, and Synthetic Horizontal-Branch Models

    DOE Data Explorer

    Dotter, A; Chaboyer, B; Jevremovic, D; Kostov, V; Baron, E; Ferguson, J; Sarajedini, A; Anderson, J

    The Dartmouth Stellar Evolution Database is a collection of stellar evolution tracks and isochrones that spans a range of [Fe/H] from -2.5 to +0.5, [a/Fe] from -0.2 to +0.8 (for [Fe/H]<=0) or +0.2 (for [Fe/H]>0), and initial He mass fractions from Y=0.245 to 0.40. Stellar evolution tracks were computed for masses between 0.1 and 4 Msolar, allowing isochrones to be generated for ages as young as 250 Myr. For the range in masses where the core He flash occurs, separate He-burning tracks were computed starting from the zero age horizontal branch. The tracks and isochrones have been transformed to the observational plane in a variety of photometric systems including standard UBV(RI)C, Stromgren uvby, SDSS ugriz, 2MASS JHKs, and HST ACS/WFC and WFPC2. The Dartmouth Stellar Evolution Database is accessible through a Web site at http://stellar.dartmouth.edu/~models/ where all tracks, isochrones, and additional files can be downloaded. [Copied from online abstract of paper titled "Darmouth Stellar Evolution Database" authored by Dotter, Chaboyer, Jevremovic, Kostov, Baron, Ferguson, and Jason. Abstract is located at http://adsabs.harvard.edu/abs/2008ApJS..178...89D] Web tools are also available at the home page (http://stellar.dartmouth.edu/~models/index.html). These tools allow users to create isochrones and convert them to luminosity functions or create synthetic horizontal branch models.

  13. Application of divided convective-dispersive transport model to simulate conservative transport processes in planted horizontal sub-surface flow constructed wetlands.

    PubMed

    Dittrich, Ernő; Klincsik, Mihály

    2015-11-01

    We have created a divided convective-dispersive transport (D-CDT) model that can be used to provide an accurate simulation of conservative transport processes in planted horizontal sub-surface flow constructed wetlands filled with coarse gravel (HSFCW-C). This model makes a fitted response curve from the sum of two independent CDT curves, which show the contributions of the main and side streams. The analytical solutions of both CDT curves are inverse Gaussian distribution functions. We used Fréchet distribution to provide a fast optimization mathematical procedure. As a result of our detailed analysis, we concluded that the most important role in the fast upward part of the tracer response curve is played by the main stream, with high porous velocity and dispersion. This gives the first inverse Gaussian distribution function. The side stream shows slower transport processes in the micro-porous system, and this shows the impact of back-mixing and dead zones, too. The significance of this new model is that it can simulate transport processes in this kind of systems more accurately than the conventionally used convective-dispersive transport (CDT) model. The calculated velocity and dispersion coefficients with the D-CDT model gave differences of 24-54% (of velocity) and 22-308% (of dispersion coeff.) from the conventional CDT model, and were closer to actual hydraulic behaviour. PMID:26178828

  14. Water displacement mercury pump

    DOEpatents

    Nielsen, M.G.

    1984-04-20

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  15. Optical displacement sensor

    DOEpatents

    Carr, Dustin W.

    2008-04-08

    An optical displacement sensor is disclosed which uses a vertical-cavity surface-emitting laser (VCSEL) coupled to an optical cavity formed by a moveable membrane and an output mirror of the VCSEL. This arrangement renders the lasing characteristics of the VCSEL sensitive to any movement of the membrane produced by sound, vibrations, pressure changes, acceleration, etc. Some embodiments of the optical displacement sensor can further include a light-reflective diffractive lens located on the membrane or adjacent to the VCSEL to control the amount of lasing light coupled back into the VCSEL. A photodetector detects a portion of the lasing light from the VCSEL to provide an electrical output signal for the optical displacement sensor which varies with the movement of the membrane.

  16. Water displacement mercury pump

    DOEpatents

    Nielsen, Marshall G.

    1985-01-01

    A water displacement mercury pump has a fluid inlet conduit and diffuser, a valve, a pressure cannister, and a fluid outlet conduit. The valve has a valve head which seats in an opening in the cannister. The entire assembly is readily insertable into a process vessel which produces mercury as a product. As the mercury settles, it flows into the opening in the cannister displacing lighter material. When the valve is in a closed position, the pressure cannister is sealed except for the fluid inlet conduit and the fluid outlet conduit. Introduction of a lighter fluid into the cannister will act to displace a heavier fluid from the cannister via the fluid outlet conduit. The entire pump assembly penetrates only a top wall of the process vessel, and not the sides or the bottom wall of the process vessel. This insures a leak-proof environment and is especially suitable for processing of hazardous materials.

  17. Polymerase chain displacement reaction.

    PubMed

    Harris, Claire L; Sanchez-Vargas, Irma J; Olson, Ken E; Alphey, Luke; Fu, Guoliang

    2013-02-01

    Quantitative PCR assays are now the standard method for viral diagnostics. These assays must be specific, as well as sensitive, to detect the potentially low starting copy number of viral genomic material. We describe a new technique, polymerase chain displacement reaction (PCDR), which uses multiple nested primers in a rapid, capped, one-tube reaction that increases the sensitivity of normal quantitative PCR (qPCR) assays. Sensitivity was increased by approximately 10-fold in a proof-of-principle test on dengue virus sequence. In PCDR, when extension occurs from the outer primer, it displaces the extension strand produced from the inner primer by utilizing a polymerase that has strand displacement activity. This allows a greater than 2-fold increase of amplification product for each amplification cycle and therefore increased sensitivity and speed over conventional PCR. Increased sensitivity in PCDR would be useful in nucleic acid detection for viral diagnostics. PMID:23384180

  18. Comparative clinical efficacy evaluation of three gingival displacement systems

    PubMed Central

    Shrivastava, Kirti Jajoo; Bhoyar, Anjali; Agarwal, Surendra; Shrivastava, Saurabh; Parlani, Swapnil; Murthy, Varsha

    2015-01-01

    Aim: We compared the clinical efficacy of three gingival displacement systems to accurately record intra-crevicular margins of tooth preparation. Materials and Methods: One mechanical (magic foam cord) and two chemico-mechanical (expasyl paste and retraction cord impregnated with 15% aluminum chloride) gingival displacement systems were used. This study was conducted on the maxillary central incisors of 20 patients (20-60 years old) requiring full coverage restoration. All the three gingival displacement systems were tested in three sessions at an interval of 14 days in same order. The casts were sectioned and viewed under an optical microscope, followed by quantitative measurements of the width of the pre and postretracted sulci. Results: All the three displacement systems produced highly significant horizontal gingival displacement. Retraction cord soaked in 15% aluminum chloride produced maximum displacement (0.74 mm), followed by expasyl paste (0.48 mm) whereas magic foam cord produced the least displacement (0.41 mm). Conclusions: Gingival displacement shown by each displacement system was found to be more than the accepted value necessary for elastomeric impression accuracy (0.2 mm) to record intra-crevicular margins of tooth preparation. PMID:26604620

  19. Simulations of the transport and deposition of 137Cs over Europe after the Chernobyl NPP accident: influence of varying emission-altitude and model horizontal and vertical resolution

    NASA Astrophysics Data System (ADS)

    Evangeliou, N.; Balkanski, Y.; Cozic, A.; Møller, A. P.

    2013-03-01

    The coupled model LMDzORINCA has been used to simulate the transport, wet and dry deposition of the radioactive tracer 137Cs after accidental releases. For that reason, two horizontal resolutions were deployed and used in the model, a regular grid of 2.5°×1.25°, and the same grid stretched over Europe to reach a resolution of 0.45°×0.51°. The vertical dimension is represented with two different resolutions, 19 and 39 levels, respectively, extending up to mesopause. Four different simulations are presented in this work; the first uses the regular grid over 19 vertical levels assuming that the emissions took place at the surface (RG19L(S)), the second also uses the regular grid over 19 vertical levels but realistic source injection heights (RG19L); in the third resolution the grid is regular and the vertical resolution 39 vertical levels (RG39L) and finally, it is extended to the stretched grid with 19 vertical levels (Z19L). The best choice for the model validation was the Chernobyl accident which occurred in Ukraine (ex-USSR) on 26 May 1986. This accident has been widely studied since 1986, and a large database has been created containing measurements of atmospheric activity concentration and total cumulative deposition for 137Cs from most of the European countries. According to the results, the performance of the model to predict the transport and deposition of the radioactive tracer was efficient and accurate presenting low biases in activity concentrations and deposition inventories, despite the large uncertainties on the intensity of the source released. However, the best agreement with observations was obtained using the highest horizontal resolution of the model (Z19L run). The model managed to predict the radioactive contamination in most of the European regions (similar to Atlas), and also the arrival times of the radioactive fallout. As regards to the vertical resolution, the largest biases were obtained for the 39 layers run due to the increase of

  20. On the effect of natural convection on solute segregation in the horizontal Bridgman configuration: Convergence of a theoretical model with numerical and experimental data

    NASA Astrophysics Data System (ADS)

    Kaddeche, S.; Garandet, J. P.; Henry, D.; Hadid, H. Ben; Mojtabi, A.

    2015-01-01

    The effect of natural convection on solute segregation in the horizontal Bridgman configuration is studied. The objective is to check whether a single non-dimensional number, based on the fluid flow induced interface shear stress, is able to capture the physics of the mass transport phenomena. A number of heat and mass transfer numerical simulations are carried out in the laminar convection regime, and the segregation results are found to be in good agreement with the predictions of the scaling analysis. At the higher convective levels relevant for the comparison with existing experimental data, a direct computation of the segregation phenomena is not possible, but numerical simulations accounting for turbulence modeling can provide the interface shear stress. With this procedure, a good agreement between the experimentally measured segregation and the predictions of the scaling analysis is again observed, thus validating the choice of the interface shear stress as a key parameter for the segregation studies.

  1. Validation of Simplified Load Equations through Loads Measurement and Modeling of a Small Horizontal-Axis Wind Turbine Tower; NREL (National Renewable Energy Laboratory)

    SciTech Connect

    Dana, S.; Damiani, R.; vanDam, J.

    2015-05-18

    As part of an ongoing effort to improve the modeling and prediction of small wind turbine dynamics, NREL tested a small horizontal axis wind turbine in the field at the National Wind Technology Center (NWTC). The test turbine was a 2.1-kW downwind machine mounted on an 18-meter multi-section fiberglass composite tower. The tower was instrumented and monitored for approximately 6 months. The collected data were analyzed to assess the turbine and tower loads and further validate the simplified loads equations from the International Electrotechnical Commission (IEC) 61400-2 design standards. Field-measured loads were also compared to the output of an aeroelastic model of the turbine. Ultimate loads at the tower base were assessed using both the simplified design equations and the aeroelastic model output. The simplified design equations in IEC 61400-2 do not accurately model fatigue loads. In this project, we compared fatigue loads as measured in the field, as predicted by the aeroelastic model, and as calculated using the simplified design equations.

  2. Horizontal drilling spurs optimism

    SciTech Connect

    Crouse, P.C. )

    1991-02-01

    1990 proved to be an exciting year for horizontal wells. This budding procedure appears to be heading for the mainstream oil and gas market, because it can more efficiently recover hydrocarbons from many reservoirs throughout the world. This paper reports on an estimated 1,000 wells that were drilled horizontally (all laterals) in 1990, with the Austin Chalk formation of Texas accounting for about 65% of all world activity. The Bakken Shale play in Montana and North Dakota proved to be the second most active area, with an estimated 90 wells drilled. Many operators in this play have indicated the bloom may be off the Bakken because of poor results outside the nose of the formation, further complicated by some of the harshest rock, reservoir and completion problems posed to horizontal technology.

  3. Extreme horizontal branch stars

    NASA Astrophysics Data System (ADS)

    Heber, U.

    A review is presented on the properties, origin and evolutionary links of hot subluminous stars which are generally believed to be extreme Horizontal Branch stars or closely related objects. They exist both in the disk and halo populations (globular clusters) of the Galaxy. Amongst the field stars a large fraction of sdBs are found to reside in close binaries. The companions are predominantly white dwarfs, but also low mass main sequence stars are quite common. Systems with sufficiently massive white dwarf companions may qualify as Supernova Ia progenitors. Recently evidence has been found that the masses of some unseen companions might exceed the Chandrasekhar mass, hence they must be neutron stars or black holes. Even a planet has recently been detected orbiting the pulsating sdB star V391 Peg. Quite to the opposite,in globular clusters, only very few sdB binaries amongst are found indicating that the dominant sdB formation processes is different in a dense environment. Binary population synthesis models identify three formation channels, (i) stable Roche lobe overflow, (ii) one or two common envelope ejection phases and (iii) the merger of two helium white dwarfs. The latter channel may explain the properties of the He-enriched subluminous O stars, the hotter sisters of the sdB stars, because their binary fraction is lower than that of the sdBs by a factor of ten or more. The rivaling ''late hot flasher'' scenario is also discussed. Pulsating subluminous B (sdB) stars play an important role for asteroseismology as this technique has already led to mass determinations for a handful of stars. A unique hyper-velocity sdO star moving so fast that it is unbound to the Galaxy has probably been ejected by the super-massive black hole in the Galactic centre.

  4. Horizontal carbon nanotube alignment.

    PubMed

    Cole, Matthew T; Cientanni, Vito; Milne, William I

    2016-09-21

    The production of horizontally aligned carbon nanotubes offers a rapid means of realizing a myriad of self-assembled near-atom-scale technologies - from novel photonic crystals to nanoscale transistors. The ability to reproducibly align anisotropic nanostructures has huge technological value. Here we review the present state-of-the-art in horizontal carbon nanotube alignment. For both in and ex situ approaches, we quantitatively assess the reported linear packing densities alongside the degree of alignment possible for each of these core methodologies. PMID:27546174

  5. Horizontal Advanced Tensiometer

    SciTech Connect

    Hubbell, Joel M.; Sisson, James B.

    2004-06-22

    An horizontal advanced tensiometer is described that allows the monitoring of the water pressure of soil positions, particularly beneath objects or materials that inhibit the use of previous monitoring wells. The tensiometer includes a porous cup, a pressure transducer (with an attached gasket device), an adaptive chamber, at least one outer guide tube which allows access to the desired horizontal position, a transducer wire, a data logger and preferably an inner guide tube and a specialized joint which provides pressure on the inner guide tube to maintain the seal between the gasket of the transducer and the adaptive chamber.

  6. Horizontal flow and capillarity-driven redistribution in porous media.

    PubMed

    Doster, F; Hönig, O; Hilfer, R

    2012-07-01

    A recent macroscopic mixture theory for two-phase immiscible displacement in porous media has introduced percolating and nonpercolating phases. Quasi-analytic solutions are computed and compared to the traditional theory. The solutions illustrate physical insights and effects due to spatiotemporal changes of nonpercolating phases, and they highlight the differences from traditional theory. Two initial and boundary value problems are solved in one spatial dimension. In the first problem a fluid is displaced by another fluid in a horizontal homogeneous porous medium. The displacing fluid is injected with a flow rate that keeps the saturation constant at the injection point. In the second problem a horizontal homogeneous porous medium is considered which is divided into two subdomains with different but constant initial saturations. Capillary forces lead to a redistribution of the fluids. Errors in the literature are reported and corrected. PMID:23005535

  7. Learned Patterns of Action-Effect Anticipation Contribute to the Spatial Displacement of Continuously Moving Stimuli

    ERIC Educational Resources Information Center

    Jordan, J. Scott; Hunsinger, Matthew

    2008-01-01

    When participants control the horizontal movements of a stimulus and indicate its vanishing point after it unexpectedly vanishes, the perceived vanishing point is displaced beyond the actual vanishing point, and the size of the displacement is directly related to the action-effect anticipation one has to generate to successfully control the…

  8. Rotary balance data for a typical single-engine general aviation design for an angle-of-attack range of 8 deg to 90 deg. 2: Influence of horizontal tail location for Model D

    NASA Technical Reports Server (NTRS)

    Barnhart, B.

    1982-01-01

    The influence of horizontal tail location on the rotational flow aerodynamics is discussed for a 1/6-scale general aviation airplane model. The model was tested using various horizontal tail positions, with both a high and a low-wing location and for each of two body lengths. Data were measured, using a rotary balance, over an angle-of-attack range of 8 to 90 deg, and for clockwise and counter-clockwise rotations covering an Omega b/2V range of 0 to 0.9.

  9. Spatially explicit model of transposon-based genetic drive mechanisms for displacing fluctuating populations of anopheline vector mosquitoes.

    PubMed

    Kiszewski, A E; Spielman, A

    1998-07-01

    To evaluate the prospect of transposon-based genetic drive mechanisms for replacing African vectors of malaria with nonvector anopheline mosquitoes, we developed a spatially explicit simulation model that determined the likelihood that released transgenic mosquitoes may proceed to fixation or extinction under diverse conditions. We compared the effect on fixation of long breeding seasons with relatively subtle population fluctuations to short breeding seasons with severe bottlenecks. Assuming 100% transposition efficiency among heterozygotes with fitness varying between 50 and 100% of that of wild-type mosquitoes, we simulated releases of 1, 10, 50, 90, and 99% of transposon-bearers in relation to wild mosquitoes as well as 1 and 10% releases that were repeated annually. We also evaluated diverse patterns of release including linear, marginal, focused, and scattered distribution. Random dispersal provided the most rapid fixation of transposons within populations. More massive releases allowed longer persistence of transposon-bearers but did not promote fixation, especially when breeding seasons were long. Relative fitness of transposon-bearers, however, proved more powerful than pattern or number of releases in determining whether a construct will become fixed or extinct. Even when fitness approaches that of the wild-type, fixation of a construct may require 150 generations or more. PMID:9701949

  10. 2.5D modelling of a horizontal electric dipole using Finite Difference method with non-uniform grids and preconditioned sparse matrices

    NASA Astrophysics Data System (ADS)

    Miranda, D. D.; Howard, A. Q.

    2012-12-01

    Computational modelling of geophysical data is an important step in the process of hydrocarbon exploration. It consists in simulating the exploratory procedure and realistic geological environments. It allows a preliminary evaluation of the exploration feasibility of a particular terrain or geological model, indicating the best conditions for geophysical surveys. In this paper, we assess the Finite Difference frequency domain method for modelling the electromagnetic response of a horizontal electric dipole in 1D and 2.5D geometries. The non-uniform grid is refined in regions where the electromagnetic fields vary rapidly, namely the regions where we have variation in conductivity distribution and near the source dipole. We chose the horizontal electromagnetic dipole because it is the source normally used in the marine controlled-source electromagnetic surveys (mCSEM), which is the next step in our research. The mCSEM, also known as Sea Bed Logging, is a method for detection and characterization of thin resistive structures, like hydrocarbon reservoirs, often located in regions of deep water. It consists of a mobile electric dipole or a magnetic loop as a source, positioned near the sea floor where an array of electric and magnetic receivers are deployed. The source transmitter uses a low frequency signal on the order of 1Hz, that diffuses both in the ocean and in the sediments beneath it and is captured by the receivers . Amplitude and phase of this signal depend on the electrical conductivity of the seabed environment. The complexity of the environments and the large dimensions of the geological domains that we want to investigate make the modelling procedure extremely demanding, since the Finite Difference method requires a total discretization of the studied domain, resulting in large systems of linear equations, which can make the procedure long and expensive. Non-uniform grids and exploitation of the sparse property of the Finite Difference matrices are example

  11. A Technology Pathway for Airbreathing, Combined-Cycle, Horizontal Space Launch Through SR-71 Based Trajectory Modeling

    NASA Technical Reports Server (NTRS)

    Kloesel, Kurt J.; Ratnayake, Nalin A.; Clark, Casie M.

    2011-01-01

    Access to space is in the early stages of commercialization. Private enterprises, mainly under direct or indirect subsidy by the government, have been making headway into the LEO launch systems infrastructure, of small-weight-class payloads of approximately 1000 lbs. These moderate gains have emboldened the launch industry and they are poised to move into the middle-weight class (roughly 5000 lbs). These commercially successful systems are based on relatively straightforward LOX-RP, two-stage, bi-propellant rocket technology developed by the government 40 years ago, accompanied by many technology improvements. In this paper we examine a known generic LOX-RP system with the focus on the booster stage (1st stage). The booster stage is then compared to modeled Rocket-Based and Turbine-Based Combined Cycle booster stages. The air-breathing propulsion stages are based on/or extrapolated from known performance parameters of ground tested RBCC (the Marquardt Ejector Ramjet) and TBCC (the SR-71/J-58 engine) data. Validated engine models using GECAT and SCCREAM are coupled with trajectory optimization and analysis in POST-II to explore viable launch scenarios using hypothetical aerospaceplane platform obeying the aerodynamic model of the SR-71. Finally, and assessment is made of the requisite research technology advances necessary for successful commercial and government adoption of combined-cycle engine systems for space access.

  12. Using Historic Models of Cn2 to predict r0 and regimes affected by atmospheric turbulence for horizontal, slant and topological paths

    SciTech Connect

    Lawson, J K; Carrano, C J

    2006-06-20

    Image data collected near the ground, in the boundary layer, or from low altitude planes must contend with the detrimental effects of atmospheric turbulence on the image quality. So it is useful to predict operating regimes (wavelength, height of target, height of detector, total path distance, day vs. night viewing, etc.) where atmospheric turbulence is expected to play a significant role in image degradation. In these regimes, image enhancement techniques such as speckle processing, deconvolution and Wiener filtering methods can be utilized to recover near instrument-limited resolution in degraded images. We conducted a literature survey of various boundary layer and lower troposphere models for the structure coefficient of the index of refraction (C{sub n}{sup 2}). Using these models, we constructed a spreadsheet tool to estimate the Fried parameter (r{sub 0}) for different scenarios, including slant and horizontal path trajectories. We also created a tool for scenarios where the height along the path crudely accounted for the topology of the path. This would be of particular interest in mountain-based viewing platforms surveying ground targets. The tools that we developed utilized Visual Basic{reg_sign} programming in an Excel{reg_sign} spreadsheet environment for accessibility and ease of use. In this paper, we will discuss the C{sub n}{sup 2} profile models used, describe the tools developed and compare the results obtained for the Fried parameter with those estimated from experimental data.

  13. Productivity and injectivity of horizontal wells

    SciTech Connect

    Aziz, Khalid

    2000-03-06

    One of the key issues addressed was pressure drop in long horizontal wells and its influence on well performance. Very little information is available in the literature on flow in pipes with influx through pipe walls. Virtually all of this work has been in small diameter pipes and with single-phase flow. In order to address this problem new experimental data on flow in horizontal and near horizontal wells have been obtained. Experiments were conducted at an industrial facility on typical 6 1/8 ID, 100 feet long horizontal well model. The new data along with available information in the literature have been used to develop new correlations and mechanistic models. Thus it is now possible to predict, within reasonable accuracy, the effect of influx through the well on pressure drop in the well.

  14. Displacement of Hexanol by the Hexanoic Acid Overoxidation Product in Alcohol Oxidation on a Model Supported Palladium Nanoparticle Catalyst

    SciTech Connect

    Buchbinder, Avram M.; Ray, Natalie A.; Lu, Junling; Van Duyne, Richard P.; Stair, Peter C.; Weitz, Eric; Geiger, Franz M.

    2011-11-09

    This work characterizes the adsorption, structure, and binding mechanism of oxygenated organic species from cyclohexane solution at the liquid/solid interface of optically flat alumina-supported palladium nanoparticle surfaces prepared by atomic layer deposition (ALD). The surface-specific nonlinear optical vibrational spectroscopy, sum-frequency generation (SFG), was used as a probe for adsorption and interfacial molecular structure. 1-Hexanoic acid is an overoxidation product and possible catalyst poison for the aerobic heterogeneous oxidation of 1-hexanol at the liquid/solid interface of Pd/Al₂O₃ catalysts. Single component and competitive adsorption experiments show that 1-hexanoic acid adsorbs to both ALD-prepared alumina surfaces and alumina surfaces with palladium nanoparticles, that were also prepared by ALD, more strongly than does 1-hexanol. Furthermore, 1-hexanoic acid adsorbs with conformational order on ALD-prepared alumina surfaces, but on surfaces with palladium particles the adsorbates exhibit relative disorder at low surface coverage and become more ordered, on average, at higher surface coverage. Although significant differences in binding constant were not observed between surfaces with and without palladium nanoparticles, the palladium particles play an apparent role in controlling adsorbate structures. The disordered adsorption of 1-hexanoic acid most likely occurs on the alumina support, and probably results from modification of binding sites on the alumina, adjacent to the particles. In addition to providing insight on the possibility of catalyst poisoning by the overoxidation product and characterizing changes in its structure that result in only small adsorption energy changes, this work represents a step toward using surface science techniques that bridge the complexity gap between fundamental studies and realistic catalyst models.

  15. Modeling the influence of tectonic extrusion and volume loss on the geometry, displacement, vorticity, and strain compatibility of ductile shear zones

    NASA Astrophysics Data System (ADS)

    Baird, Graham B.; Hudleston, Peter J.

    2007-10-01

    Oblate strains are often observed in meso-scale ductile shear zones and this is generally taken to indicate narrowing across the shear zone during formation. Volume loss is one mechanism that could produce shear zone narrowing. However, not all shear zones display characteristics consistent with volume loss, and in such cases, the narrowing must be accomplished by the extrusion of material from within the shear zone. To explore the relationship between shear zone geometry, volume loss, and extrusion, shear zones were mathematically modeled. Results demonstrate the important influence of pure shear and volume loss on controlling the geometry, displacement, and vorticity of ductile shear zones. Further, volume loss does not preclude extrusion unless, for a given volume loss, the strain is of a specific geometry. Extrusion is a likely mechanism important in shear zone development, even if volume loss occurs. Extrusion presents strain compatibility problems because, unlike crustal-scale shear zones, meso-scale ductile shear zones do not possess a free surface. If extrusion occurs, bulk strain compatibility can be maintained if shear zones interlink in anastomosing arrays or change in thickness, though not all shear zone systems display such characteristics. Modeling results elucidate the deformation style of shear zone in the northwest Adirondacks in NY and in the Kebnekaise region in northern Sweden.

  16. Numerical modeling of the thermal and hydrological environment around a nuclear waste package using the equivalent continuum approximation: Horizontal emplacement

    SciTech Connect

    Nitao, J.J.

    1988-05-01

    In support of the investigations for an underground high-level nuclear waste repository at Yucca Mountain, Nevada, we have performed computer simulations of the immediate thermal and hydrological environment around a nuclear waste package. Calculations of this type will be needed for waste package design, performance assessment, and radionuclide transport analyses. Two dimensional computer simulations using a modified version of the TOUGH code were run for an idealized configuration derived from the COVE3 benchmarking effort consisting of a single spent fuel waste package with laterally periodic boundary conditions. The model domain extended downward to the water table and upward to the ground level. Fluid behavior in the rock was modeled using the equivalent continuum approximation. Runs were made with surface water influx rates at the surface set to 0.1, 0.5, and 1.0 mm/yr. A significant amount of code modification and development was needed in order to develop the capability to run these types of problems out to the long time spans required. 26 refs., 59 figs.

  17. RTV 21 Displacements

    SciTech Connect

    Kurita, C.H.; /Fermilab

    1987-02-04

    A seal is needed for the cover of the Nitrogen Test Vessel in order to prevent leakage of the N{sub 2} gas. This seal is to be molded out of RTV 21. In this experiment, the Modulus of Elasticity of the RTV was sought after, and the displacements of the RTV due to various stresses were measured to see if they were large enough to provide a tight seal between the vessel and its cover.

  18. Data assimilation of surface displacements to improve geomechanical parameters of gas storage reservoirs

    NASA Astrophysics Data System (ADS)

    Zoccarato, C.; Baó, D.; Ferronato, M.; Gambolati, G.; Alzraiee, A.; Teatini, P.

    2016-03-01

    Although the beginning of reservoir geomechanics dates back to the late 1960s, only recently stochastical geomechanical modelling has been introduced into the general framework of reservoir operational planning. In this study, the ensemble smoother (ES) algorithm, i.e., an ensemble-based data assimilation method, is employed to reduce the uncertainty of the constitutive parameters characterizing the geomechanical model of an underground gas storage (UGS) field situated in the upper Adriatic sedimentary basin (Italy), the Lombardia UGS. The model is based on a nonlinear transversely isotropic stress-strain constitutive law and is solved by 3-D finite elements. The Lombardia UGS experiences seasonal pore pressure change caused by fluid extraction/injection leading to land settlement/upheaval. The available observations consist of vertical and horizontal time-lapse displacements accurately measured by persistent scatterer interferometry (PSI) on RADARSAT scenes acquired between 2003 and 2008. The positive outcome of preliminary tests on simplified cases has supported the use of the ES to jointly assimilate vertical and horizontal displacements. The ES approach is shown to effectively reduce the spread of the uncertain parameters, i.e., the Poisson's ratio, the ratio between the horizontal and vertical Young and shear moduli, and the ratio between the virgin loading (I cycle) and unloading/reloading (II cycle) compressibility. The outcomes of the numerical simulations point out that the updated parameters depend on the assimilated measurement locations as well as the error associated to the PSI measurements. The parameter estimation may be improved by taking into account possible model and/or observation biases along with the use of an assimilation approach, e.g., the Iterative ensemble smoother, more appropriate for nonlinear problems.

  19. Alginate as a displacer for protein displacement chromatography.

    PubMed

    Chen, G; Scouten, W H

    1996-01-01

    Alginate use in displacement chromatography as a displacer has been studied. The experiments showed that untreated alginate is the basis of potential displacer for displacement chromatography, but needs to be cleaved into smaller chains. Alginate treated with ultrasound, which cleaves alginate into shorter polysaccharide chains, gave better displacement than untreated alginate, while alginate subjected to limited acid hydrolysis gave the best results in displacement chromatography. It was found that the mixture of ovalbumin and beta-lactoglobulin separated well, and several components of ovalbumin were also separated and purified when alginate hydrolysate was used as a displacer. beta-Lactoglobulins A and B, which have the same molecular weight and differ in isoelectric point by only 0.1 pH units, were displaced from Q-Sepharose by alginate hydrolysate. PMID:9174919

  20. Analysis of Tip Vortices Identified in the Instantaneous Wake of a Horizontal-Axis Model Wind Turbine Placed in a Turbulent Boundary Layer

    NASA Astrophysics Data System (ADS)

    Jain, Akash; Mehdi, Faraz; Sheng, Jian

    2014-11-01

    The near-wake field, a short region characterized by the physical specifications of a turbine, is of particular interest for flow-structure interactions responsible for asymmetric loadings, premature structural breakdown, noise generation etc. Helical tip vortices constitute a distinctive feature of this region and are dependent not only on the turbine geometry but also on the incoming flow profile. High-spatial resolution PIV measurements are made in the wake of a horizontal-axis model wind turbine embedded in a neutrally stratified turbulent boundary layer. The data is acquired over consecutive locations up to 10 diameters downstream of the turbine but the focus here is on the tip vortices identified in the instantaneous fields. Contrary to previous studies, both top and bottom tip vortices are clearly distinguishable in either ensemble fields or instantaneous realizations. The streamwise extent of these vortices stretches from the turbine till they merge into the expanding mid-span wake. The similarities and differences in the top and bottom tip vortices are explored through the evolution of their statistics. In particular, the distributions of the loci of vortex cores and their circulations are compared. The information will improve our understanding of near wake vortical dynamics, provide data for model validation, and aid in the devise of flow control strategies.

  1. Simulation of the transport of Rn222 using on-line and off-line global models at different horizontal resolutions: a detailed comparison with measurements

    NASA Astrophysics Data System (ADS)

    Dentener, Frank; Feichter, Johann; Jeuken, Ad

    1999-07-01

    The short-lived radionuclide Rn222 is emitted at a fairly constant rate from the continents and is a good surrogate for studying the transport of "air pollution" from polluted continental areas to clean, remote regions. The large concentration gradients of 2 3 orders of magnitude which exist between the continents and the remote atmosphere present a major challenge to the modelling of horizontal and vertical atmospheric transport. We use the global off-line tracer transport model TM3 at 3 different resolutions. Input to the model consists of meteorological data for the year 1993 obtained from the European Centre for Medium Range Weather Forecasts (ECMWF). The same meteorological data is used to constrain the climate model ECHAM4-T42-L19. Using these meteorological data, Rn222 simulations are used to evaluate and document model performance and associated uncertainties. High time-resolution measurements made at 2 continental stations, 2 stations under continental influence and 4 remote sites, and aircraft measurements obtained during the NARE aircraft campaign are used for a detailed comparison.Although in specific regions there are inter-model differences of up to a factor of 2 in the calculated boundary layer concentrations, these differences are not translated into a better performance of either model for the stations used for comparison. We generally obtain high correlations of model results and measurements; these range from r= 0.6 0.8 for the continental and coastal stations and 0.5 0.6 for the remote sites. Calculated mean concentrations and corresponding standard deviations generally agree favourably with observations, lending credibility to the usefulness of our models for evaluating transport of air pollutants from continental sources to remote regions. The main cause of model deviations is probably related to uncertainties in the meteorological input data set provided by the ECMWF model and to a lesser extent by our knowledge of the spatial distribution of

  2. In vitro binding of leukotriene B4 (LTB4) to human serum albumin: evidence from spectroscopic, molecular modeling, and competitive displacement studies.

    PubMed

    Zsila, Ferenc; Bikádi, Zsolt; Lockwood, Samuel F

    2005-08-15

    Circular dichroism (CD) and UV absorption spectroscopy were utilized for the first time to investigate the interaction between leukotriene B4 (LTB4) and human serum albumin (HSA) in vitro. The weak intrinsic CD signal of LTB4 was enhanced fivefold in the presence of HSA. The red-shifted, hypochromic, and reduced vibrational fine structure of the ligand/protein UV absorption spectrum indicated complexation of the two molecules in solution. Results obtained from CD titration experiments were subjected to non-linear regression analysis to estimate the binding parameters (Ka = 6.7 x 10(4) M(-1), n = 1). Palmitic acid strongly decreased the induced CD signal of the LTB4/HSA complex, suggesting the role of a high-affinity fatty acid HSA binding site in the leukotriene complexation. Molecular modeling calculations based on the crystal structure of HSA predicted that the long-chain fatty acid site that overlaps with drug binding site II in subdomain IIIA was the most likely binding location for LTB4. Using the drug site II-specific marker ligand rac-ibuprofen, this prediction was confirmed with induced-CD displacement measurements. To the authors' knowledge, the current study represents the first demonstration of binding of LTB4 to HSA in vitro and has implications for the biological transport of this important pro-inflammatory mediator in vivo. PMID:15993588

  3. Roles of land surface albedo and horizontal resolution on the Indian summer monsoon biases in a coupled ocean-atmosphere tropical-channel model

    NASA Astrophysics Data System (ADS)

    Samson, Guillaume; Masson, Sébastien; Durand, Fabien; Terray, Pascal; Berthet, Sarah; Jullien, Swen

    2016-05-01

    The Indian summer monsoon (ISM) simulated over the 1989-2009 period with a new 0.75° ocean-atmosphere coupled tropical-channel model extending from 45°S to 45°N is presented. The model biases are comparable to those commonly found in coupled global climate models (CGCMs): the Findlater jet is too weak, precipitations are underestimated over India while they are overestimated over the southwestern Indian Ocean, South-East Asia and the Maritime Continent. The ISM onset is delayed by several weeks, an error which is also very common in current CGCMs. We show that land surface temperature errors are a major source of the ISM low-level circulation and rainfall biases in our model: a cold bias over the Middle-East (ME) region weakens the Findlater jet while a warm bias over India strengthens the monsoon circulation over the southern Bay of Bengal. A surface radiative heat budget analysis reveals that the cold bias is due to an overestimated albedo in this desertic ME region. Two new simulations using a satellite-observed land albedo show a significant and robust improvement in terms of ISM circulation and precipitation. Furthermore, the ISM onset is shifted back by 1 month and becomes in phase with observations. Finally, a supplementary set of simulations at 0.25°-resolution confirms the robustness of our results and shows an additional reduction of the warm and dry bias over India. These findings highlight the strong sensitivity of the simulated ISM rainfall and its onset timing to the surface land heating pattern and amplitude, especially in the ME region. It also illustrates the key-role of land surface processes and horizontal resolution for improving the ISM representation, and more generally the monsoons, in current CGCMs.

  4. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Joint, Vertical Cross Bracing End Detail - Ceylon Covered Bridge, Limberlost Park, spanning Wabash River at County Road 900 South, Geneva, Adams County, IN

  5. Relating reactive solute transport to hierarchical and multiscale sedimentary architecture in a Lagrangian-based transport model: 2. Particle displacement variance

    NASA Astrophysics Data System (ADS)

    Soltanian, Mohamad Reza; Ritzi, Robert W.; Huang, Chao Cheng; Dai, Zhenxue

    2015-03-01

    This series of papers addresses the transport of sorbing solutes in groundwater. In part 2, plume dispersion, as quantified by the particle displacement variance, X11R>(t>), is linked to hierarchical sedimentary architecture using a Lagrangian-based transport model. This allows for a fundamental understanding of how dispersion arises from the hierarchical architecture of sedimentary facies, and allows for a quantitative decomposition of dispersion into facies-related contributions at different scales within the hierarchy. As in part 1, the plume behavior is assumed to be controlled by linear-equilibrium sorption and the heterogeneity in both the log permeability, Y=ln⁡>(k>), and the log distribution coefficient, Ξ=ln⁡>(Kd>). Heterogeneity in Y and Ξ arises from sedimentary processes and is structured by the consequent sedimentary architecture. Our goal is to understand the basic science of the dispersion process at this very fundamental level. The spatial auto and cross covariances for the relevant attributes are linear sums of terms corresponding to the probability of transitioning across stratal facies types defined at different scales. Unlike previous studies that used empirical relationships for the spatial covariances, here the model parameters are developed from independent measurements of physically quantifiable attributes of the stratal architecture (i.e., proportions and lengths of facies types, and univariate statistics for Y and Ξ). Nothing is assumed about Y-Ξ point correlation; it is allowed to differ by facies type. However, it is assumed that Y and Ξ variance is small but meaningful, and that pore-scale dispersion is negligible. The time-dependent spreading rate is a function of the effective ranges of the cross-transition probability structures (i.e., the ranges of indicator correlation structures) for each relevant scale of stratal hierarchy. As in part 1, the well-documented perchloroethene (PCE) tracer test at the Borden research site is

  6. Horizontal geophone transducer assembly

    SciTech Connect

    Hefer, F.W.

    1985-06-25

    The geophone transducer comprises in combination: a geophone capable of detecting horizontal seismic waves, and a rigid casing having a gimbal chamber. A gimbal is provided inside the chamber on which the geophone is mounted for limited free angular movement in one direction only. The gimbal includes in one preferred embodiment a viscous liquid in which the geophone is only partially submerged while it is supported by a U-shaped bracket which is mounted for rotation about a fixed axis.

  7. Experimental Determination of the Effect of Horizontal-Tail Size, Tail Length, and Vertical Location on Low-Speed Static Longitudinal Stability and Damping Pitch of a Model Having 45 Degree Sweptback Wing and Tail Surfaces

    NASA Technical Reports Server (NTRS)

    Lichtenstein, Jacob H

    1952-01-01

    Report presents the results of an investigation conducted in the Langley stability tunnel to determine the effects of horizontal tails of various sizes and at various tail lengths (when loaded on the fuselage center line) and also the effects of vertical location of the horizontal tail relative to the wing on the low-speed static longitudinal stability and on the steady-state rotary damping in pitch for a complete-model configuration. The wing and tail surfaces had the quarter-chord lines swept back 45 degrees and had aspect ratios of 4. The results of the investigation showed that, in agreement with analytical considerations, the contribution of the horizontal tail to static longitudinal stability was related directly to the tail size and length; whereas, its contribution to damping in pitch was related directly to tail size and the square of tail length.

  8. Improving horizontal resolution of high-frequency surface-wave methods using travel-time tomography

    NASA Astrophysics Data System (ADS)

    Yin, Xiaofei; Xu, Hongrui; Wang, Limin; Hu, Yue; Shen, Chao; Sun, Shida

    2016-03-01

    In surface-wave methods, horizontal resolution can be defined as the ability to distinguish anomalous objects that are laterally displaced from each other. The horizontal length of a recognizable geological anomalous body is measured by the lateral variation of shear (S)-wave velocity. Multichannel analysis of surface waves (MASW) is an efficient tool to determine near-surface S-wave velocities. The acquisition of the MASW method involves the same source-receiver configuration moved successively by a fixed distance interval (a few to several stations) along a linear survey line, which is called a roll-along acquisition geometry. A pseudo-2D S-wave velocity section is constructed by aligning 1D models, and each inverted 1D S-wave velocity model reflects the vertical S-wave velocity variation at the midpoint of each geophone spread. Although the MASW method can improve the horizontal resolution of S-wave velocity sections to some degree, the amount of fieldwork is increased by the roll-along acquisition geometry. We propose surface-wave tomography method to investigate horizontal resolution of surface-wave exploration. Phase-velocity dispersion curves are calculated by a pair of traces within a multichannel record through cross-correlation combined with a phase-shift scanning method. Then with the utilization of travel-time tomography, we can obtain high resolution pure-path dispersion curves with diverse sizes of grids at different frequencies. Finally, the pseudo-2D S-wave velocity structure is reconstructed by inverting the pure-path dispersion curves. Travel-time tomography of surface waves can extract accurate dispersion curves from a record with a short receiver spacing, and it can effectively enhance the ability of random noise immunity. Synthetic tests and a real-world example have indicated that travel-time tomography has a great potential for improving the horizontal resolution of surface waves using multi-channel analysis.

  9. Importance of wave-number dependence of Biot numbers in one-sided models of evaporative Marangoni instability: Horizontal layer and spherical droplet.

    PubMed

    Machrafi, H; Rednikov, A; Colinet, P; Dauby, P C

    2015-05-01

    A one-sided model of the thermal Marangoni instability owing to evaporation into an inert gas is developed. Two configurations are studied in parallel: a horizontal liquid layer and a spherical droplet. With the dynamic gas properties being admittedly negligible, one-sided approaches typically hinge upon quantifying heat and mass transfer through the gas phase by means of transfer coefficients (like in the Newton's cooling law), which in dimensionless terms eventually corresponds to using Biot numbers. Quite a typical arrangement encountered in the literature is a constant Biot number, the same for perturbations of different wavelengths and maybe even the same as for the reference state. In the present work, we underscore the relevance of accounting for its wave-number dependence, which is especially the case in the evaporative context with relatively large values of the resulting effective Biot number. We illustrate the effect in the framework of the Marangoni instability thresholds. As a concrete example, we consider HFE-7100 (a standard refrigerant) for the liquid and air for the inert gas. PMID:26066259

  10. Mixed convection flow over a horizontal circular cylinder with constant heat flux embedded in a porous medium filled by a nanofluid: Buongiorno-Darcy model

    NASA Astrophysics Data System (ADS)

    Tham, Leony; Nazar, Roslinda; Pop, Ioan

    2015-11-01

    The steady laminar mixed convection boundary layer flow from a horizontal circular cylinder in a nanofluid embedded in a porous medium, which is maintained at a constant surface heat flux, has been studied by using the Buongiorno-Darcy nanofluid model for both cases of a heated and cooled cylinder. The resulting system of nonlinear partial differential equations is solved numerically using an implicit finite-difference scheme known as the Keller box method. The solutions for the flow and heat transfer characteristics are evaluated numerically and studied for various values of the governing parameters, namely the Lewis number, Brownian number, mixed convection parameter, buoyancy ratio parameter and thermophoresis parameter. It is also found that the boundary layer separation occurs at the opposing fluid flow, that is when the mixed convection parameter is negative. It is also observed that increasing the mixed convection parameter delays the boundary layer separation and the separation can be completely suppressed for sufficiently large values of the mixed convection parameter. The Brownian and buoyancy ratio parameters appear to affect the fluid flow and heat transfer profiles.

  11. An electromechanical displacement transducer

    NASA Astrophysics Data System (ADS)

    Villiers, Marius; Mahboob, Imran; Nishiguchi, Katsuhiko; Hatanaka, Daiki; Fujiwara, Akira; Yamaguchi, Hiroshi

    2016-08-01

    Two modes of an electromechanical resonator are coupled through the strain inside the structure with a cooperativity as high as 107, a state-of-the-art value for purely mechanical systems, which enables the observation of normal-mode splitting. This coupling is exploited to transduce the resonator’s fundamental mode into the bandwidth of the second flexural mode, which is 1.4 MHz higher in frequency. Thus, an all-mechanical heterodyne detection scheme is implemented that can be developed into a high-precision displacement sensor.

  12. Synthesis of finite displacements and displacements in continental margins

    NASA Technical Reports Server (NTRS)

    Speed, R. C.; Elison, M. W.; Heck, F. R.; Russo, R. M.

    1988-01-01

    The scope of the project is the analysis of displacement-rate fields in the transitional regions between cratonal and oceanic lithospheres over Phanerozoic time (last 700 ma). Associated goals are an improved understanding of range of widths of major displacement zones; the partition of displacement gradients and rotations with position and depth in such zones; the temporal characteristics of such zones-the steadiness, episodicity, and duration of uniform versus nonunifrom fields; and the mechanisms and controls of the establishment and kinematics of displacement zones. The objective is to provide a context of time-averaged kinematics of displacement zones. The initial phase is divided topically among the methodology of measurement and reduction of displacements in the lithosphere and the preliminary analysis from geologic and other data of actual displacement histories from the Cordillera, Appalachians, and southern North America.

  13. Displacement sensor for indoor machine calibrations.

    PubMed

    Mudassar, Asloob Ahmad; Butt, Saira

    2013-05-20

    This paper presents a simple displacement sensor for indoor machine calibrations. The sensor, which is placed in the path of a diverging laser beam, consists of two plane mirror pieces laterally displaced with the line joining their centers initially held perpendicular to the optical axis of the beam during the displacement of the sensor with one of the mirrors always traveling along the optical axis of the laser beam. The optical signals from the two mirrors are combined and a simple detector at the interference plane counts the fringes during the sensor displacement. The sensor could be mounted on the moving head of any mechanical machine, e.g., the lathe machine for displacement calibration. The device has been tested over a range of 10 cm beyond a distance of 150 cm from a diverging laser source giving an accuracy of 1.1015 μm. Theoretical modeling, simulation, and experimental results are presented which establish that the proposed sensor can be used as a promising displacement measuring device. PMID:23736230

  14. Stress-relief displacements induced by drilling--applications to holographic measurements of in situ stress. Final technical report, August 15, 1988--August 14, 1990

    SciTech Connect

    Ahrens, T.J.; Smither, C.L.

    1992-04-24

    The holographic stressmeter is an instrument which has been developed at Caltech to allow determination of the complete stress tensor from in situ borehole measurements. The stressmeter uses double-exposure holographic interferometry to record the displacements induced by the drilling of a small sidehole into the borehole wall. The local stresses, which are the result of the far-field stresses, concentrated at the borehole, cause deformation of the surface of the borehole wall in the vicinity of the sidehole. The first part of this study uses a thin infinite elastic plate subjected to plane stress at infinity to model the displacements at the borehole wall. However, the existence of some holograms which were difficult to model closely led us to examine the validity of this model. In order to investigate the problem further, we performed a two-dimensional finite element analysis for an elastic box with a terminated hole. We varied the dimensions of the hole to see what effect the radius and depth of the hole might have on the displacements. The plate model predicts that the depth of the hole should have no effect on the horizontal components of displacement, but the finite element results show that the magnitude of both components of the displacement depends on the depth of the sidehole. After considering these results, we developed a new model for the analysis of stress-relief displacements, following the work of Youngdahl and Sternberg (1965). For holes with a depth-to-diameter ratio greater than unity, the simple plane stress elastic plate solution breaks down and does not adequately model the displacements at the surface of the body and near the hole. Since these are the areas most critical to calculate accurately with the holographic technique, the revised model does a better job of fitting the observed data.

  15. Syndrome of transtentorial herniation: is vertical displacement necessary?

    PubMed Central

    Ropper, A H

    1993-01-01

    MRI from a comatose patient with a massive acute subdural haematoma showed most of the features of transtentorial herniation described in the classic pathology literature. In addition to encroachment on the perimesencephalic cisterns, infarction in the anterior and posterior cerebral artery territories, ischaemic change in the lower diencephalon, and ventricular enlargement were visualised. Despite the clinical syndrome and these secondary changes due to compression, there was only approximately 2 mm of downward displacement of the upper brainstem compared with 13 mm horizontal displacement. Although tissue shifts adjacent to the tentorial aperture cause brainstem and vascular compression, these changes may occur with minimal downward herniation. Images PMID:8350117

  16. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; Haynes, C.D.; Mazza, R.L.

    1992-06-01

    The objectives of this joint horizontal drilling effort by the US DOE and Belden & Blake in the complex, low permeability Clinton Sandstone will focus on the following objectives: (1) apply horizontal drilling technology in hard, abrasive, and tight Clinton Sandstone; (2) evaluate effects of multiple hydraulic fracturing in a low permeability horizontal wellbore; (3) assess economic viability of horizontal drilling in the Clinton and similar tight gas sands.

  17. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; Haynes, C.D.; Mazza, R.L.

    1992-01-01

    The objectives of this joint horizontal drilling effort by the US DOE and Belden Blake in the complex, low permeability Clinton Sandstone will focus on the following objectives: (1) apply horizontal drilling technology in hard, abrasive, and tight Clinton Sandstone; (2) evaluate effects of multiple hydraulic fracturing in a low permeability horizontal wellbore; (3) assess economic viability of horizontal drilling in the Clinton and similar tight gas sands.

  18. Effects of Surface Epitope Coverage on the Sensitivity of Displacement Assays that Employ Modified Nanoparticles: Using Bisphenol A as a Model Analyte.

    PubMed

    Lu, Yang; Peterson, Joshua Richard; Luais, Erwann; Gooding, John Justin; Lee, Nanju Alice

    2016-01-01

    With the ever-increasing use of nanoparticles in immunosensors, a fundamental study on the effect of epitope density is presented herein, with a small molecule epitope, on the performance of the displacement assay format in an enzyme-linked immunosorbent assay (ELISA). Thiolated bisphenol A (BPA) functionalized gold nanoparticles (cysBPAv-AuNPs) and specific anti-BPA antibodies are employed for this purpose. It is shown that the displacement of cysBPAv-AuNPs bound to the immobilized antibodies was influenced by both the avidity of bound cysBPAv-AuNPs and the concentration of free BPA to displace it. The importance of surface epitope density was that it changed the number of epitopes in close proximity to the antibody-binding site. This then influenced the avidity of cysBPAv-AuNPs bound to the immobilized antibody. Furthermore, the molar epitope concentration in an assay appears to affect the degree of antibody binding site saturation. Controlling surface epitope density of the functionalized nanoparticles and molar epitope concentration in an assay leads to a decrease of the concentration of free BPA required to displace the bound cysBPAv-AuNP, and hence better assay performance with regards to the D50 value and dynamic range in the displacement assay. PMID:27509530

  19. Do infants have the horizontal bias?

    PubMed

    Van Renswoude, D R; Johnson, S P; Raijmakers, M E J; Visser, I

    2016-08-01

    A robust set of studies show that adults make more horizontal than vertical and oblique saccades, while scanning real-world scenes. In this paper we study the horizontal bias in infants. The directions of eye movements were calculated for 41 infants (M=8.40 months, SD=3.74, range=3.48-15.47) and 47 adults (M=21.74 years, SD=4.54, range=17.89-39.84) while viewing 28 real-world scenes. Saccade directions were binned to study the proportion of saccades in the horizontal, vertical and oblique directions. In addition, saccade directions were also modeled using a mixture of Von Mises distributions, to account for the relatively large amount of variance in infants data. Horizontal bias was replicated in adults and also found in infants, using both the binning and Von Mises approach. Moreover, a developmental pattern was observed in which older infants are more precise in targeting their saccades than younger infants. That infants have a horizontal bias is important in understanding infants' eye movements. Future studies should account for the horizontal bias in their designs and analyses. PMID:27281348

  20. Adapting to variable prismatic displacement

    NASA Technical Reports Server (NTRS)

    Welch, Robert B.; Cohen, Malcolm M.

    1989-01-01

    In each of two studies, subjects were exposed to a continuously changing prismatic displacement with a mean value of 19 prism diopters (variable displacement) and to a fixed 19-diopter displacement (fixed displacement). In Experiment 1, significant adaptation (post-pre shifts in hand-eye coordination) was found for fixed, but not for variable, displacement. Experiment 2 demonstrated that adaptation was obtained for variable displacement, but it was very fragile and is lost if the measures of adaptation are preceded by even a very brief exposure of the hand to normal or near-normal vision. Contrary to the results of some previous studies, an increase in within-S dispersion was not found of target pointing responses as a result of exposure to variable displacement.

  1. [Survival analysis of German Holstein cows after an abomasal displacement].

    PubMed

    Ricken, M; Hamann, H; Scholz, H; Distl, O

    2005-02-01

    From 1996 to 2002 5159 cattle with abomasal displacement was treated in the Clinic for Cattle, School of Veterinary Medicine Hannover. An analysis of systematic effects on influences on the length of survival following surgical correction of the abomasal displacement could be performed for 1411 cows. These animals were under the official milk recording scheme. Significant influences on lifetime after an abomasal displacement were interval between calving and diagnosis of disease, lactation number, type of abomasal displacement, inbreeding coefficient, calving difficulties, region of origin and sire of the calf. The lifetime after an abomasal displacement significantly differed between several months of calving and some sires of the cow. The individual milk yield in lactations before and after abomasal displacement of the cow was significant for the length of lifetime. The heritability estimate for length of lifetime after abomasal displacement using residual maximum likelihood (REML) in a linear animal model was h2 = 0.01-0.03. PMID:15787315

  2. On the value of including x-component data in 1D modeling of electromagnetic data from helicopterborne time domain systems in horizontally layered environments

    NASA Astrophysics Data System (ADS)

    Kirkegaard, Casper; Foged, Nikolaj; Auken, Esben; Christiansen, Anders Vest; Sørensen, Kurt

    2012-09-01

    Helicopter borne time domain EM systems historically measure only the Z-component of the secondary field, whereas fixed wing systems often measure all field components. For the latter systems the X-component is often used to map discrete conductors, whereas it finds little use in the mapping of layered settings. Measuring the horizontal X-component with an offset loop helicopter system probes the earth with a complementary sensitivity function that is very different from that of the Z-component, and could potentially be used for improving resolution of layered structures in one dimensional modeling. This area is largely unexplored in terms of quantitative results in the literature, since measuring and inverting X-component data from a helicopter system is not straightforward: The signal strength is low, the noise level is high, the signal is very sensitive to the instrument pitch and the sensitivity function also has a complex lateral behavior. The basis of our study is a state of the art inversion scheme, using a local 1D forward model description, in combination with experiences gathered from extending the SkyTEM system to measure the X component. By means of a 1D sensitivity analysis we motivate that in principle resolution of layered structures can be improved by including an X-component signal in a 1D inversion, given the prerequisite that a low-pass filter of suitably low cut-off frequency can be employed. In presenting our practical experiences with modifying the SkyTEM system we discuss why this prerequisite unfortunately can be very difficult to fulfill in practice. Having discussed instrumental limitations we show what can be obtained in practice using actual field data. Here, we demonstrate how the issue of high sensitivity towards instrument pitch can be overcome by including the pitch angle as an inversion parameter and how joint inversion of the Z- and X-components produces virtually the same model result as for the Z-component alone. We conclude that

  3. Co-seismic vertical displacements from a single post-seismic lidar DEM: example from the 2010 El Mayor-Cucapah earthquake

    NASA Astrophysics Data System (ADS)

    Barišin, Ivana; Hinojosa-Corona, Alejandro; Parsons, Barry

    2015-07-01

    A method is outlined by means of which it is possible to estimate high-resolution vertical displacements due to an earthquake even in the case where high-resolution topography is lacking before the earthquake. This result can be achieved by combining a highly accurate, post-event digital elevation model (DEM), for example lidar, with archived satellite imagery. The method is illustrated by calculating vertical displacements for the 2010 El Mayor-Cucapah earthquake. For this earthquake, there are both pre- and post-event lidar DEMs from which vertical displacements may also be estimated after correcting for the lateral advection of topography due to horizontal displacements. A comparison between the two means of deriving vertical displacements shows generally good agreement, with the displacements obtained using satellite imagery performing better in high relief areas. As a result of this property, we are able to trace the vertical offsets due to the El Mayor-Cucapah earthquake as the rupture jumped from the Pescadores fault to the Borrego fault in propagating through the high relief of the Sierra Cucapah.

  4. Design and performance of a horizontal mooring for upper-ocean research

    USGS Publications Warehouse

    Grosenbaugh, Mark; Anderson, Steven; Trask, Richard; Gobat, Jason; Paul, Walter; Butman, Bradford; Weller, Robert

    2002-01-01

    This paper describes the design and performance of a two-dimensional moored array for sampling horizontal variability in the upper ocean. The mooring was deployed in Massachusetts Bay in a water depth of 84 m for the purpose of measuring the horizontal structure of internal waves. The mooring was instrumented with three acoustic current meters (ACMs) spaced along a 170-m horizontal cable that was stretched between two subsurface buoys 20 m below the sea surface. Five 25-m-long vertical instrument strings were suspended from the horizontal cable. A bottom-mounted acoustic Doppler current profiler (ADCP) was deployed nearby to measure the current velocity throughout the water column. Pressure sensors mounted on the subsurface buoys and the vertical instrument strings were used to measure the vertical displacements of the array in response to the currents. Measurements from the ACMs and the ADCP were used to construct time-dependent, two-dimensional current fields. The current fields were used as input to a numerical model that calculated the deformation of the array with respect to the nominal zero-current configuration. Comparison of the calculated vertical offsets of the downstream subsurface buoy and downstream vertical instrument string with the pressure measurements were used to verify the numerical code. These results were then used to estimate total deformation of the array due to the passage of the internal waves. Based on the analysis of the three internal wave events with the highest measured vertical offsets, it is concluded that the geometry of the main structure (horizontal cable and anchor legs) was kept to within ±2.0 m, and the geometry of the vertical instrument strings was kept to within ±4.0 m except for one instance when the current velocity reached 0.88 m s−1.

  5. Horizontal baffle for nuclear reactors

    DOEpatents

    Rylatt, John A.

    1978-01-01

    A horizontal baffle disposed in the annulus defined between the core barrel and the thermal liner of a nuclear reactor thereby physically separating the outlet region of the core from the annular area below the horizontal baffle. The horizontal baffle prevents hot coolant that has passed through the reactor core from thermally damaging apparatus located in the annulus below the horizontal baffle by utilizing the thermally induced bowing of the horizontal baffle to enhance sealing while accommodating lateral motion of the baffle base plate.

  6. How minimum detectable displacement in a GNSS Monitoring Network change?

    NASA Astrophysics Data System (ADS)

    Hilmi Erkoç, Muharrem; Doǧan, Uǧur; Aydın, Cüneyt

    2016-04-01

    The minimum detectable displacement in a geodetic monitoring network shows the displacement magnitude which may be just discriminated with known error probabilities. This displacement, which is originally deduced from sensitivity analysis, depends on network design, observation accuracy, datum of the network, direction of the displacement and power of the statistical test used for detecting the displacements. One may investigate how different scenarios on network design and observation accuracies influence the minimum detectable displacements for the specified datum, a-priorly forecasted directions and assumed power of the test and decide which scenario is the best or most optimum. It is sometimes difficult to forecast directions of the displacements. In that case, the minimum detectable displacements in a geodetic monitoring network are derived on the eigen-directions associated with the maximum eigen-values of the network stations. This study investigates how minimum detectable displacements in a GNSS monitoring network change depending on the accuracies of the network stations. For this, CORS-TR network in Turkey with 15 stations (a station fixed) is used. The data with 4h, 6h, 12 h and 24 h observing session duration in three sequential days of 2011, 2012 and 2013 were analyzed with Bernese 5.2 GNSS software. The repeatabilities of the daily solutions belonging to each year were analyzed carefully to scale the Bernese cofactor matrices properly. The root mean square (RMS) values for daily repeatability with respect to the combined 3-day solution are computed (the RMS values are generally less than 2 mm in the horizontal directions (north and east) and < 5 mm in the vertical direction for 24 h observing session duration). With the obtained cofactor matrices for these observing sessions, the minimum detectable displacements along the (maximum) eigen directions are compared each other. According to these comparisons, more session duration less minimum detectable

  7. Variable displacement blower

    DOEpatents

    Bookout, Charles C.; Stotts, Robert E.; Waring, Douglass R.; Folsom, Lawrence R.

    1986-01-01

    A blower having a stationary casing for rotatably supporting a rotor assembly having a series of open ended chambers arranged to close against the surrounding walls of the casing. Pistons are slidably mounted within each chamber with the center of rotation of the pistons being offset in regard to the center of rotation of the rotor assembly whereby the pistons reciprocate in the chambers as the rotor assembly turns. As inlet port communicates with the rotor assembly to deliver a working substance into the chamber as the pistons approach a top dead center position in the chamber while an outlet port also communicates with the rotor to exhaust the working substance as the pistons approach a bottom dead center position. The displacement of the blower is varied by adjusting the amount of eccentricity between the center of rotation of the pistons and the center of rotation of the rotor assembly.

  8. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    SciTech Connect

    Lee, Gwang-Se; Cheong, Cheolung

    2014-12-15

    Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs), few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF) wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF) noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson’s acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson’s analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  9. Prediction and analysis of infra and low-frequency noise of upwind horizontal axis wind turbine using statistical wind speed model

    NASA Astrophysics Data System (ADS)

    Lee, Gwang-Se; Cheong, Cheolung

    2014-12-01

    Despite increasing concern about low-frequency noise of modern large horizontal-axis wind turbines (HAWTs), few studies have focused on its origin or its prediction methods. In this paper, infra- and low-frequency (the ILF) wind turbine noise are closely examined and an efficient method is developed for its prediction. Although most previous studies have assumed that the ILF noise consists primarily of blade passing frequency (BPF) noise components, these tonal noise components are seldom identified in the measured noise spectrum, except for the case of downwind wind turbines. In reality, since modern HAWTs are very large, during rotation, a single blade of the turbine experiences inflow with variation in wind speed in time as well as in space, breaking periodic perturbations of the BPF. Consequently, this transforms acoustic contributions at the BPF harmonics into broadband noise components. In this study, the ILF noise of wind turbines is predicted by combining Lowson's acoustic analogy with the stochastic wind model, which is employed to reproduce realistic wind speed conditions. In order to predict the effects of these wind conditions on pressure variation on the blade surface, unsteadiness in the incident wind speed is incorporated into the XFOIL code by varying incident flow velocities on each blade section, which depend on the azimuthal locations of the rotating blade. The calculated surface pressure distribution is subsequently used to predict acoustic pressure at an observing location by using Lowson's analogy. These predictions are compared with measured data, which ensures that the present method can reproduce the broadband characteristics of the measured low-frequency noise spectrum. Further investigations are carried out to characterize the IFL noise in terms of pressure loading on blade surface, narrow-band noise spectrum and noise maps around the turbine.

  10. Wind-Tunnel Investigation at Subsonic and Supersonic Speeds of a Fighter Model Employing a Low-aspect-ratio Unswept Wing and a Horizontal Tail Mounted Well above the Wing Plane - Lateral and Directional Stability

    NASA Technical Reports Server (NTRS)

    Wetzel, Benton E.

    1954-01-01

    The static lateral- and directional-stability characteristics of a high-speed fighter-type airplane, obtained from wind-tunnel tests of a model, are presented. The model consisted of a thin, unswept wing of aspect ratio 2.3 and taper ratio 0.385, a body, and a horizontal tail mounted in a high position on a vertical tail. Rolling-moment, yawing moment, and cross-wind-force coefficients are presented for a range of sideslip angles of -5 deg. to +5 deg, for Mach numbers of 0.90, 1.45, and 1.90. Data are presented which show the effects on the lateral and directional stability of: (1) component parts of the complete model, (2) modification of the empennage so as to provide different heights of the horizontal tail above the wing plane, (3) angle of attack, and (4) dihedral of the wing.

  11. Articulating Support for Horizontal Resistive Exercise

    NASA Technical Reports Server (NTRS)

    Gundo, Daniel; Schaffner, Grant; Bentley, Jason; Loehr, James A.

    2005-01-01

    A versatile mechanical device provides support for a user engaged in any of a variety of resistive exercises in a substantially horizontal orientation. The unique features and versatility of the device promise to be useful in bedrest studies, rehabilitation, and specialized strength training. The device affords a capability for selectively loading and unloading of portions of the user s body through its support mechanisms, so that specific parts of the body can be trained with little or no effect on other parts that may be disabled or in the process of recovery from injury. Thus, the device is ideal for rehabilitation exercise programs prescribed by physicians and physical therapists. The capability for selective loading and support also offers potential benefits to strength and conditioning trainers and athletes who wish to selectively strengthen selected parts. The principal innovative aspect of the device is that it supports the subject s weight while enabling the subject, lying substantially horizontally, to perform an exercise that closely approximates a full standing squat. The device includes mechanisms that support the subject in such a way that the hips are free to translate both horizontally and vertically and are free to rotate about the line connecting the hips. At the same time, the shoulders are free to translate horizontally while the upper back is free to rotate about the line connecting the shoulders. Among the mechanisms for hip motion and support is a counterbalance that offsets the weight of the subject as the subject s pelvis translates horizontally and vertically and rotates the pelvis about the line connecting the hips. The counterbalance is connected to a pelvic support system that allows these pelvic movements. The subject is also supported at the shoulder by a mechanism that can tilt to provide continuous support of the upper back while allowing the rotation required for arching the back as the pelvis is displaced. The shoulder support

  12. Meridional displacement of the East Asian trough and its response to the ENSO forcing

    NASA Astrophysics Data System (ADS)

    Leung, Marco Y.-T.; Cheung, Hoffman H. N.; Zhou, Wen

    2016-03-01

    This paper examined the underlying dynamic mechanisms associated with the meridional displacement of the East Asian trough (EAT), which is closely related to the temperature variability in the southern part of East Asian winter monsoon (EAWM). During the southward displacement of the EAT, the Siberian high is stronger and the Aleutian low is displaced southward. This is due mainly to the anomalous cyclonic flow associated with seasonal eddies over the midlatitude central Pacific, which enhances the horizontal advection of cold (warm) air to the southern (northern) part of the EAT in the lower troposphere. The cold (warm) advection narrows (thickens) the height thickness and results in negative (positive) temperature anomalies in the southern (northern) part of the EAT. These anomalous circulation features can be reasonably explained by the phase of the El Niño-Southern Oscillation (ENSO). The results are also verified by the numerical experiments with prescribing ENSO-like heat source anomalies over the tropical eastern and western Pacific in an anomaly atmospheric general circulation model. All of these results advance our understanding for the linkage between the ENSO and the EAWM via its modulation of the EAT.

  13. Wind-Tunnel Investigation at Subsonic and Supersonic Speeds of a Fighter Model Employing a Low-Aspect-Ratio Unswept Wing and a Horizontal Tail Mounted Well Above the Wing Plane - Longitudinal Stability and Control

    NASA Technical Reports Server (NTRS)

    Smith, Williard G.

    1954-01-01

    Experimental results showing the static longitudinal-stability and control characteristics of a model of a fighter airplane employing a low-aspect-ratio unswept wing and an all-movable horizontal tail are presented. The investigation was made over a Mach number range from 0.60 to 0.90 and from 1.35 to 1.90 at a constant Reynolds number of 2.40 million, based on the wing mean aerodynamic chord. Because of the location of the horizontal tail at the tip of the vertical tail, interference was noted between the vertical tail and the horizontal tail and between the wing and the horizontal tail. This interference produced a positive pitching-moment coefficient at zero lift throughout the Mach number range of the tests, reduced the change in stability with increasing lift coefficient of the wing at moderate lift coefficients in the subsonic speed range, and reduced the stability at low lift coefficients at high supersonic speeds. The lift and pitching-moment effectiveness of the all movable tail was unaffected by the interference effects and was constant throughout the lift-coefficient range of the tests at each Mach number except 1.90.

  14. HORIZONTAL BOILING REACTOR SYSTEM

    DOEpatents

    Treshow, M.

    1958-11-18

    Reactors of the boiling water type are described wherein water serves both as the moderator and coolant. The reactor system consists essentially of a horizontal pressure vessel divided into two compartments by a weir, a thermal neutronic reactor core having vertical coolant passages and designed to use water as a moderator-coolant posltioned in one compartment, means for removing live steam from the other compartment and means for conveying feed-water and water from the steam compartment to the reactor compartment. The system further includes auxiliary apparatus to utilize the steam for driving a turbine and returning the condensate to the feed-water inlet of the reactor. The entire system is designed so that the reactor is self-regulating and has self-limiting power and self-limiting pressure features.

  15. Horizontally shaken impact pendulums

    NASA Astrophysics Data System (ADS)

    Alexander, T. J.; Xu, Y.; Sidhu, H.

    2016-03-01

    We consider two pendulum masses attached to the same pivot point and which interact with each other through Hertzian impacts. We show that this splitting of the mass leads to an instability in the conservative case, in which initially synchronized large amplitude motion may evolve into out-of-phase (impacting) motion. We then study in detail the response of the impacting masses in the presence of damping and driving through horizontal shaking of the pivot point. We find that synchronized modes are usually accompanied by small amplitude quasi-periodic, or even chaotic, impacts and a number of multi-period solutions may appear in the bifurcation diagram. We reveal the existence and stability of a number of impact modes and scan the frequency response of the system to a series of initial conditions to identify which modes may be more easily generated in experiment.

  16. Horizontal Motions of Faulting Dictate the 26 December 2004 Tsunami Genesis

    NASA Astrophysics Data System (ADS)

    Song, Y.; Fu, L.; Zlotnicki, V.; Ji, C.; Hjorleifsdottir, V.; Shum, C.; Yi, Y.

    2006-12-01

    For a long time, people have believed that the vertical motion of faulting during an undersea earthquake is the main cause of tsunamis. However, independent evidence from seismographs, satellite radar altimeters, and tide gauges have revealed that the lateral collision force of a continental slope into the ocean due to faulting was the main cause of the devastating 2004 tsunami. Seismically-inverted seafloor displacements of the Sumatra-Andaman earthquake show that the horizontal motions of faulting in that tsunami generated kinetic energy 5 times larger than the potential energy due to the vertical motion. Two different ocean models by rigorously using the seismic inversion have confirmed that the horizontal force accounted for about 70 percent of the satellite-observed tsunami height. The asymmetric tsunami pattern and arrival times, recorded by tide gauges showing "leading depression N-waves" toward Thailand and "leading elevation N-waves" toward Sri Lanka, are best explained by the horizontally-forced mechanism. The developed method has also been successfully tested on the Mach 2005 tsunami, suggesting that tsunami genesis can be predicted directly from seismic signals.

  17. Color opponency in cone-driven horizontal cells in carp retina. Aspecific pathways between cones and horizontal cells

    PubMed Central

    1991-01-01

    The spectral and dynamic properties of cone-driven horizontal cells in carp retina were evaluated with silent substitution stimuli and/or saturating background illumination. The aim of this study was to describe the wiring underlying the spectral sensitivity of these cells. We will present electrophysiological data that indicate that all cone- driven horizontal cell types receive input from all spectral cone types, and we will present evidence that all cone-driven horizontal cell types feedback to all spectral cone types. These two findings are the basis for a model for the spectral and dynamic behavior of all cone- driven horizontal cells in carp retina. The model can account for the spectral as well as the dynamic behavior of the horizontal cells. It will be shown that the strength of the feedforward and feedback pathways between a horizontal cell and a particular spectral cone type are roughly proportional. This model is in sharp contrast to the Stell model, where the spectral behavior of the three horizontal cell types is explained by a cascade of feedforward and feedback pathways between cones and horizontal cells. The Stell model accounts for the spectral but not for the dynamic behavior of the horizontal cells. PMID:1711573

  18. Atomistic Simulation of Displacement Cascades in Zircon

    SciTech Connect

    Devanathan, Ram; Weber, William J.; Corrales, Louis R.; BP McGrail and GA Cragnolino

    2002-05-06

    Low energy displacement cascades in zircon (ZrSiO4) initiated by a Zr primary knock-on atom have been investigated by molecular dynamics simulations using a Coulombic model for long-range interactions, Buckingham potential for short-range interactions and Ziegler-Biersack potentials for close pair interactions. Displacements were found to occur mainly in the O sublattice, and O replacements by a ring mechanism were predominant. Clusters containing Si interstitials bridged by O interstitials, vacancy clusters and anti-site defects were found to occur. This Si-O-Si bridging is considerable in quenched liquid ZrSiO4.

  19. Fibre optic distributed differential displacement sensor

    NASA Astrophysics Data System (ADS)

    Wylie, Michael T. V.; Brown, Anthony W.; Colpitts, Bruce G.

    2011-05-01

    A Fibre Optic Distributed Differential Displacement Sensor is modelled and experimentally verified to determine shape. Created using a steel tape, 9/125 μm single mode fibre, and adhesive, the FODDDS can be used to determine shape or displacement of any object to which it is bonded. A circular shape is examined, and a radius of curvature comparison yields an error of 2%. The sensitivity of the FODDDS, for the substrate thickness used in this experiment, is shown to be 1.27 mm between adjacent data points, which corresponds to a radius of curvature of 103 m.

  20. Effective area of a horizontal long-wire antenna collecting the atmospheric electric vertical current

    NASA Astrophysics Data System (ADS)

    Tammet, H.; Israelsson, S.; Knudsen, E.; Tuomi, T. J.

    1996-12-01

    The effective area of an antenna collecting the vertical air-Earth current is a coefficient of proportionality between the collected current and the air-Earth current density. The effective area can be correctly defined only if the model behind the proportionality relation is adequate. The current collected by a horizontal long-wire antenna is not exactly proportional to the vertical air-Earth Maxwell current density because of the different behavior of the displacement and conduction components of the current. Thus, two different effective areas are separately defined for the displacement and nondisplacement components. First, the dynamic effective area characterizes rapid variations of the displacement current. It is calculated assuming that the air does not contain any space charges and that the electric current flow lines match the electric field lines. Second, the static effective area characterizes the nondisplacement current, and it is calculated by taking into account the facts that the conductivity close to the wire surface is unipolar, that the wind-determined horizontal ion trajectories do not match the electric field lines, and that there are space charges due to the electrode effect of the wire and of the ground. Traditionally, the atmospheric electric vertical current density measurements have been interpreted by using the dynamic effective area as a calibration coefficient. This turns out to be a satisfactory approximation in the case of strong turbulence when the near-ground space charge layer is high and the static effective area approaches the dynamic effective area. In the limit of low turbulence the traditional interpretation results in errors of several tens percent. A reduced height of the antenna helps to keep the static effective area close to the dynamic effective area and to suppress the errors.

  1. Rotary Steerable Horizontal Directional Drilling: Red River Formation

    NASA Astrophysics Data System (ADS)

    Cherukupally, A.; Bergevin, M.; Jones, J.

    2011-12-01

    Sperry-Sun Drilling, a Halliburton company provides engineering solutions and sets new records for Horizontal and Vertical Displacement Drilling (HVDD). Halliburton Sperry Drilling, Casper, WY, allowed one student to participate in 12-week experiential learning program this summer as HVDD engineer. HVDD is the science of drilling non-vertical wells and can be differentiated into three main groups; Oilfield Directional Drilling (ODD), Utility Installation Directional Drilling (UIDD) and in-seam directional Drilling. Sperry-Sun prior experience with rotary drilling established a number of principles for the configuration of Bottom Hole Assembly (BHA) that would be prone to drilling crooked hole [1]. Combining Measurement While Drilling survey tools (MWD tools) and BHA designs made HVDD possible. Geologists use the MWD survey data to determine the well placement in the stratigraphic sequence. Through the analysis of this data, an apparent dip of the formation can be calculated, and the bit is directed to stay in the target zone of production. Geological modeling assists in directing the well by creating a map of the target zone surface, an Isopach map. The Isopach map provides contour intervals and changes in formation dip. When the inclination of the formation changes the geologist informs the directional drillers to adjust the drill bits. HVDD provides Halliburton the opportunity to reach more production intervals in a given formation sequence [1]. The Down hole motors powered by fluid flow through the drill string create horsepower and rotation of the bit which enables the use of a bend element in the BHA to create the tilt necessary to deviate the wellbore from vertical displacement drilling path. The rotation of Down hole motors is influenced by temperature and aromatics found in water, oil and diesel based mud. The development of HVDD Rotary Steerable tools hold promise to have almost a complete automated process for drilling highly deviated production well

  2. Wind-Tunnel Investigation at Low Speed of the Effects of Chordwise Wing Fences and Horizontal-Tail Position on the Static Longitudinal Stability Characteristics of an Airplane Model with a 35 Degree Sweptback Wing

    NASA Technical Reports Server (NTRS)

    Queijo, M J; Jaquet, Byron M; Wolhart, Walter D

    1954-01-01

    Low-speed tests of a model with a wing swept back 35 degrees at the 0.33-chord line and a horizontal tail located well above the extended wing-chord plane indicated static longitudinal instability at moderate angles of attack for all configurations tested. An investigation therefore was made to determine whether the longitudinal stability could be improved by the use of chordwise wing fences, by lowering the horizontal tail, or by a combination of both. The results of the investigation showed that the longitudinal stability characteristics of the model with slats retracted could be improved at moderate angles of attack by placing chordwise wing fences at a spanwise station of about 73 percent of the wing semispan from the plane of symmetry provided the nose of the fence extended slightly beyond or around the wing leading edge.

  3. Passive magnetic bearing for a horizontal shaft

    DOEpatents

    Post, Richard F.

    2003-12-02

    A passive magnetic bearing is composed of a levitation element and a restorative element. The levitation element is composed of a pair of stationary arcuate ferromagnetic segments located within an annular radial-field magnet array. The magnet array is attached to the inner circumference of a hollow shaft end. An attractive force between the arcuate segments and the magnet array acts vertically to levitate the shaft, and also in a horizontal transverse direction to center the shaft. The restorative element is comprised of an annular Halbach array of magnets and a stationary annular circuit array located within the Halbach array. The Halbach array is attached to the inner circumference of the hollow shaft end. A repulsive force between the Halbach array and the circuit array increases inversely to the radial space between them, and thus acts to restore the shaft to its equilibrium axis of rotation when it is displaced therefrom.

  4. Analysis of tidal signals in surface displacement measured by a dense continuous GPS array

    NASA Astrophysics Data System (ADS)

    Yuan, Linguo; Chao, Benjamin F.

    2012-11-01

    We analyze the tidal displacement signals, for the eight major diurnal and semidiurnal tides, from Global Positioning System (GPS) measurements made at the Western United States over the past 16 years with 1075 independent stations. By careful examinations among inland versus coastal GPS data we are able to demonstrate that estimated precisions down to the level of ˜0.1 mm (horizontal) and ˜0.3 mm (vertical) have been reached for the tidal signals, and that at such precisions coherent spatial patterns are revealed in the residual tidal amplitudes and phases after the removal of a priori modeled effects of body tides and ocean tidal loading (OTL). We demonstrate the facility of modern precise GPS data in not only constraining the ocean tide models but, more significantly, in providing source data in terms of regional, complex Love numbers for geophysical inference of the heterogeneities of elastic and inelastic structures in the solid Earth's deep interior on tidal timescales.

  5. Uniform head in horizontal and vertical wells

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The steady-state head within a fully penetrating well may be estimated by evaluating the Thiem equation at the radius of the well. A method is presented here to extend results from the Thiem equation to horizontal wells and to partially penetrating wells. The particular model used in this investigat...

  6. Horizontal drilling in shallow reservoirs

    SciTech Connect

    Murray, W.F. Jr.; Schrider, L.A.; McCallister, J.V.; Mazza, R.L.

    1993-12-31

    Belden & Blake and the US DOE will cofund a horizontal well to be drilled in the Clinton Sandstone as part of the DOE`s multi well program titled ``Horizontal Drilling in Shallow Geologic Complex Reservoirs.`` This well will be located in Mahoning County, Ohio in an area which has demonstrated above average Clinton gas production. To the best of our knowledge, this will be the first horizontal well drilled to the Clinton Sand formation in Ohio. Since many of the remaining Clinton Sand drilling sites are of poorer reservoir quality, they may not be developed unless technology such as horizontal drilling can be successfully demonstrated.

  7. A Modified Stress-Displacement Solution for a Pressure Tunnel with a Permeable Liner in an Elastic Porous Medium Based on a New Model

    NASA Astrophysics Data System (ADS)

    Wang, M. B.; Wang, G.

    2013-03-01

    Referring to previous literature, the elastic problem for a deep pressure tunnel with a permeable liner in a saturated elastic porous medium that obeys Terzaghi's effective stress principle is further investigated. In the analysis, the influences of the changes of the pore water pressure around the opening, the construction sequence of the tunnel, and the interaction between the liner and the surrounding geomaterial on the mechanical response of the tunnel are appropriately considered. Also, the influences of the relative liner thickness and rigidity and the relative distance of the point under investigation from the tunnel axis on the stress-displacement fields for various combinations of the mechanical and geometric parameters are numerically evaluated and discussed. The results indicate that both the support pressure and displacement increase monotonically with increasing liner rigidity and thickness. The influence of the tunnel excavation upon the displacement field is significantly larger than upon the stress field. Either too high or too low values for the relative rigidity and thickness of the liner are unfavorable for structural stability.

  8. Displacement, Substitution, Sublimation: A Bibliography.

    ERIC Educational Resources Information Center

    Pedrini, D. T.; Pedrini, Bonnie C.

    Sigmund Freund worked with the mechanisms of displacement, substitution, and sublimation. These mechanisms have many similarities and have been studied diagnostically and therapeutically. Displacement and substitution seem to fit in well with phobias, hysterias, somatiyations, prejudices, and scapegoating. Phobias, prejudices, and scapegoating…

  9. Estimating the macroanisotropy of a horizontally layered section from controlled-source radiomagnetotelluric soundings

    NASA Astrophysics Data System (ADS)

    Shlykov, A. A.; Saraev, A. K.

    2015-07-01

    The possibilities of estimating the macroanisotropic parameters of the earth by radiomagnetotelluric soundings with a controlled source in the form of a horizontal electric dipole (a cable with a finite length) are studied in the case of the measurements in the transition zone of the source, where the galvanic and induction modes of the excited electromagnetic field are both important. The forward problem for the considered high frequency band (up to 1000 kHz) is solved with allowance for the displacement currents in the ground and air. The algorithm of anisotropic 1D inversion of the sounding data is presented. The resolution parameters are estimated from the derivatives of the electromagnetic field components with respect to the model parameters. Based on the synthetic examples, it is shown that joint inversion of the impedance and tipper data in the transition zone of the source constrains the space of equivalent models and makes it possible to determine the macroanisotropy coefficient of the section.

  10. Evaluating the CALIOPE air quality modelling system: dynamics and chemistry over Europe and Iberian Peninsula for 2004 at high horizontal resolution

    NASA Astrophysics Data System (ADS)

    Piot, M.; Pay, M. T.; Jorba, O.; Baldasano, J. M.; Jiménez-Guerrero, P.; López, E.; Pérez, C.; Gassó, S.

    2009-04-01

    Peninsula simulation at 4 km horizontal resolution, every hour. In order to evaluate the performances of the CALIOPE system, model simulations were compared with ground-based measurements from the EMEP and Spanish air quality networks. For the European domain, 45 stations have been used to evaluate NO2, 60 for O3, 39 for SO2, 25 for PM10 and 16 for PM2.5. On the other hand, the Iberian Peninsula domain has been evaluated against 75 NO2 stations, 84 O3 stations, 69 for SO2, and 46 for PM10. Such large number of observations allows us to provide a detailed discussion of the model skills over quite different geographical locations and meteorological situations. The model simulation for Europe satisfactorily reproduces O3 concentrations throughout the year with relatively small errors: MNGE values range from 13% to 24%, and MNBE values show a slight negative bias ranging from -15% to 0%. These values lie within the range defined by the US-EPA guidelines (MNGE: +/- 30-35%; MNBE: +/- 10-15%). NO2 is less accurately simulated, with a mean MNBE of -47% caused by an overall underestimation in concentrations. The reproduction of SO2 concentrations is relatively correct but false peaks are reported (mean MNBE=22%). The simulated variation of particulate matter is reliable, with a mean correlation of 0.5. False peaks were reduced by use of an improved 8-bin aerosol description in the DREAM dust model, but mean aerosol levels are still underestimated. This problem is most probably related to uncertainties in our knowledge of the sources and in the description of the sulfate chemistry. The model simulation for Europe will be used to force the nested high-resolution simulation of the Iberian Peninsula. The performances of the latter will be also presented. Such high resolution simulation will allow analysing the small scale features observed over Spain. REFERENCES Baldasano J.M, P. Jiménez-Guerrero, O. Jorba, C. Pérez, E. López, P. Güereca, F. Martin, M. García-Vivanco, I. Palomino

  11. Uncovering deformation processes from surface displacements

    NASA Astrophysics Data System (ADS)

    Stramondo, Salvatore

    2013-04-01

    The aim of this talk is to provide an overview about the most recent outcomes in Earth Sciences, describe the role of satellite remote sensing, together with GPS, ground measurement and further data, for geophysical parameter retrieval in well known case studies where the combined approach dealing with the use of two or more techniques/datasets have demonstrated their effectiveness. The Earth Sciences have today a wide availability of instruments and sensors able to provide scientists with an unprecedented capability to study the physical processes driving earthquakes, volcanic eruptions, landslides, and other dynamic Earth systems. Indeed measurements from satellites allow systematic observation of the Earth surface covering large areas, over a long time period and characterized by growing sample intervals. Interferometric Synthetic Aperture Radar (InSAR) technique has demonstrated its effectiveness to investigate processes responsible for crustal faulting stemming from the detection of surface deformation patterns. Indeed using satellite data along ascending and descending orbits, as well as different incident angles, it is possible in principle to retrieve the full 3D character of the ground motion. To such aim the use of GPS stations providing 3D displacement components is a reliable complementary instrument. Finally, offset tracking techniques and Multiple Aperture Interferometry (MAI) may provide a contribution to the analysis of horizontal and NS deformation vectors. The estimation of geophysical parameters using InSAR has been widely discussed in seismology and volcanology, and also applied to deformation associated with groundwater and other subsurface fluids. These applications often involve the solution of an inverse problem, which means the retrieval of optimal source parameters at depth for volcanoes and earthquakes, from the knowledge of surface deformation from InSAR. In recent years, InSAR measurements combined with traditional seismological and

  12. DNS of Horizontal Convection

    NASA Astrophysics Data System (ADS)

    White, Brian; Scotti, Alberto

    2014-11-01

    We perform three-dimensional DNS of Horizontal Convection in a rectangular tank with idealized boundary conditions. The flow is driven by imposing the profile for the buoyancy b at the surface, where it ranges from b0 to b0 + Δb and the transition region is confined to a very small area. The Rayleigh based on the domain depth ranges from 105 to 1012. The scaling observed for the Nusselt number and the strength of the circulation is consistent with Rossby's scaling across the range of Rayleigh numbers considered, indicating that the dynamics in the boundary layer under the ``warming'' side throttles the flow. Energetically, we find that Available Potential Energy (APE) is generated along the surface, and converted to Kinetic Energy (KE). Along the descending plume energy goes from APE to KE up to Ra ~1011 . For higher Rayleigh numbers the plume becomes a net sink of APE. When the switch occurs, a stagnant layer develops near the bottom, and the overall circulation becomes characterized by a narrow plume which retroflects rapidly towards the surface, with a shallow recirculation to close the flow. This may indicate the beginning of a Sandström regime characterized by a stagnant abyssal region and a shallow circulation. Work supported by the National Science Foundation.

  13. The Consequences of Job Displacement for Health: Moderating Influences of Economic Conditions and Educational Attainment

    PubMed Central

    Pearlman, Jessica

    2015-01-01

    This paper will examine the impact of worker displacement on health in the United States from 1975–2004, especially the extent to which the impact of displacement on health varies according to the economic conditions in the year of displacement and the education level of the displaced worker. Findings from ordered probit and fixed effects models suggest that the negative impact of displacement on health is exacerbated by a higher unemployment rate at the time of displacement and for displaced workers with a college degree. PMID:26004481

  14. Annual maximum 5-day rainfall total and maximum number of consecutive dry days over Central America and the Caribbean in the late twenty-first century projected by an atmospheric general circulation model with three different horizontal resolutions

    NASA Astrophysics Data System (ADS)

    Nakaegawa, T.; Kitoh, A.; Murakami, H.; Kusunoki, S.

    2014-04-01

    We simulated changes in annual maximum 5-day rainfall (RX5D) and annual maximum number of consecutive dry days (CDD) in Central America, Mexico, and the Caribbean with three different horizontal resolution atmospheric global general circulation models (AGCMs) and quantified the uncertainty of the projections. The RX5Ds and CDDs were projected to increase in most areas in response to global warming. However, consistent changes were confined to small areas: for RX5D, both coastal zones of northern Mexico and the Yucatan Peninsula; for CDD, the Pacific coastal zone of Mexico, the Yucatan Peninsula, and Guatemala. All three AGCMs projected that RX5Ds and CDDs averaged over only the land area and over the entire area (land and ocean) would increase. The dependence of RX5D probability density functions on the horizontal resolutions was complex. Precipitation unrelated to tropical cyclones was primarily responsible for the projected increases in the frequency of RX5Ds greater than 300 mm.

  15. Understanding Horizontal Governance. Research Brief

    ERIC Educational Resources Information Center

    Ferguson, Daniel

    2009-01-01

    Horizontal governance is an umbrella term that covers a range of approaches to policy development, service delivery issues, and management practices. A horizontal initiative may take place across levels of government, across boundaries between units of a single department or agency or among multiple departments or agencies, or across public,…

  16. Calibration of a Horizontal Sundial

    ERIC Educational Resources Information Center

    Rovsek, Barbara

    2010-01-01

    This paper describes how a horizontal sundial can be calibrated in a classroom without using the nontrivial equations of projective geometry. If one understands how a simple equatorial sundial works, one will also understand the procedure of calibrating a horizontal (or "garden," as it is also called) sundial.

  17. Retrieving three-dimensional displacement fields of mining areas from a single InSAR pair

    NASA Astrophysics Data System (ADS)

    Li, Zhi Wei; Yang, Ze Fa; Zhu, Jian Jun; Hu, Jun; Wang, Yun Jia; Li, Pei Xian; Chen, Guo Liang

    2015-01-01

    This paper presents a novel method for retrieving three-dimensional (3-D) displacement fields of mining areas from a single interferometric synthetic aperture radar (InSAR) pair. This method fully exploits the mechanism of mining subsidence, specifically the proportional relationship between the horizontal displacement and horizontal gradient of vertical displacements caused by underground mining. This method overcomes the limitations of conventional InSAR techniques that can only measure one-dimensional (1-D) deformation of mining area along the radar line-of-sight direction. The proposed method is first validated with simulated 3-D displacement fields, which are obtained by the FLAC software. The root mean square errors of the 3-D displacements retrieved by the proposed method are 13.7, 27.6 and 3.6 mm for the West-East, North-South, and Up-Down components, respectively. We then apply the proposed method to estimate the 3-D displacements of the Qianyingzi and the Xuzhou coal mines in China, respectively, each along with two Advanced Land Observing Satellite (ALOS) Phased Array Type L-band Synthetic Aperture Radar images. Results show that the estimated 3-D displacement is highly consistent with that of the field surveying. This demonstrates that the proposed method is an effective approach for retrieving 3-D mining displacement fields and will play an important role in mining-related hazard prevention and environment assessment under limited InSAR acquisitions.

  18. Regenerative rotary displacer Stirling engine

    SciTech Connect

    Isshiki, Naotsugu; Watanabe, Hiroichi; Raggi, L.; Isshiki, Seita; Hirata, Koichi

    1996-12-31

    A few rotary displacer Stirling engines in which the displacer has one gas pocket space at one side and rotates in a main enclosed cylinder, which is heated from one side and cooled from opposite side without any regenerator, have been studied for some time by the authors. The authors tried to improve this engine by equipping it with a regenerator, because without a regenerator, pressure oscillation and efficiency are too small. Here, several types of regenerative rotary displacer piston Stirling engines are proposed. One is the contra-rotating tandem two disc type displacer engine using axial heat conduction through side walls or by heat pipes and another is a single disc type with circulating fluid regenerator or heat pipes. Stirling engines of this new rotary displacer type are thought to attain high speed. Here, experimental results of the original rotary displacer Stirling engine without a regenerator, and one contra-rotating tandem displacer engine with side wall regenerator by axial heat conduction are reported accompanied with a discussion of the results.

  19. Landslide displacement measurements from Optical Satellite Images: A Case Study on the North Anatolian Fault Zone

    NASA Astrophysics Data System (ADS)

    Turk, Tarik; Gorum, Tolga; Birdal, Anil Can; Tatar, Orhan

    2015-04-01

    Several geodetic and remote sensing methods are used to monitor the movements due to the tectonic and geomorphic processes and the assessment of associated hazards. Recent advances in image-correlation techniques and high resolution satellite imaging at meter resolution offer the possibility to measure surface displacements with sub-metric accuracy. Moreover, this methods enables an accurate mapping of the surface displacements, and vector visualization of the horizontal movements over a period through establishing correlation among the different dated satellite images belonging to the same area. This study analyzes the displacement pattern of the earth flows using sub-pixel image correlation techniques along the tectonic Kelkit Valley, Central Anatolia, Turkey. In this study, we used Co-Registration of Optically Sensed Images and Correlation (Cosi-Corr) to measure the horizontal surface displacement of landslides from SPOT-5 images. The significance of the horizontal displacement results was verified through fieldwork studies. The landslide displacement vectors obtained from SPOT 5 (2.5 meter resolution) optical satellite images on 11 August 2006 and 21 September 2011 indicate that many of the old landslides reactivated in the study area. It was determined that such reactivation occurred due to the secondary slides developed inside the main body of the old landslides, especially in their accumulation sections. The horizontal displacement values in the accumulation sections of the old landslides vary between 4.9 and -7.7 meters in the North-South direction and between 8.2 and -5 meters in the East-West direction. The maximum displacement values were observed in the eastern hill-slopes. The results show that the Cosi-Corr technique provides important contributions in the determination of the landslide movements especially with very slow, slow to moderate slip velocities and their deformation quantities and patterns. Acknowledgements This research was financially

  20. Surface displacements in the 1906 san francisco and 1989 loma prieta earthquakes.

    PubMed

    Segall, P; Lisowski, M

    1990-11-30

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes. PMID:17829210

  1. Surface displacements in the 1906 San Francisco and 1989 Loma Prieta earthquakes

    USGS Publications Warehouse

    Segall, P.; Lisowski, M.

    1990-01-01

    The horizontal displacements accompanying the 1906 San Francisco earthquake and the 1989 Loma Prieta earthquake are computed from geodetic survey measurements. The 1906 earthquake displacement field is entirely consistent with right-lateral strike slip on the San Andreas fault. In contrast, the 1989 Loma Prieta earthquake exhibited subequal components of strike slip and reverse faulting. This result, together with other seismic and geologic data, may indicate that the two earthquakes occurred on two different fault planes.

  2. Borehole optical lateral displacement sensor

    DOEpatents

    Lewis, R.E.

    1998-10-20

    There is provided by this invention an optical displacement sensor that utilizes a reflective target connected to a surface to be monitored to reflect light from a light source such that the reflected light is received by a photoelectric transducer. The electric signal from the photoelectric transducer is then imputed into electronic circuitry to generate an electronic image of the target. The target`s image is monitored to determine the quantity and direction of any lateral displacement in the target`s image which represents lateral displacement in the surface being monitored. 4 figs.

  3. Computing Fault Displacements from Surface Deformations

    NASA Technical Reports Server (NTRS)

    Lyzenga, Gregory; Parker, Jay; Donnellan, Andrea; Panero, Wendy

    2006-01-01

    Simplex is a computer program that calculates locations and displacements of subterranean faults from data on Earth-surface deformations. The calculation involves inversion of a forward model (given a point source representing a fault, a forward model calculates the surface deformations) for displacements, and strains caused by a fault located in isotropic, elastic half-space. The inversion involves the use of nonlinear, multiparameter estimation techniques. The input surface-deformation data can be in multiple formats, with absolute or differential positioning. The input data can be derived from multiple sources, including interferometric synthetic-aperture radar, the Global Positioning System, and strain meters. Parameters can be constrained or free. Estimates can be calculated for single or multiple faults. Estimates of parameters are accompanied by reports of their covariances and uncertainties. Simplex has been tested extensively against forward models and against other means of inverting geodetic data and seismic observations. This work

  4. Study of the Local Horizon. (Spanish Title: Estudio del Horizonte Local.) Estudo do Horizonte Local

    NASA Astrophysics Data System (ADS)

    Ros, Rosa M.

    2009-12-01

    The study of the horizon is fundamental to easy the first observations of the students at any education center. A simple model, to be developed in each center, allows to easy the study and comprehension of the rudiments of astronomy. The constructed model is presented in turn as a simple equatorial clock, other models (horizontal and vertical) may be constructed starting from it. El estudio del horizonte es fundamental para poder facilitar las primeras observaciones de los alumnos en un centro educativo. Un simple modelo, que debe realizarse para cada centro, nos permite facilitar el estudio y la comprensión de los primeros rudimentos astronómicos. El modelo construido se presenta a su vez como un sencillo modelo de reloj ecuatorial y a partir de él se pueden construir otros modelos (horizontal y vertical). O estudo do horizonte é fundamental para facilitar as primeiras observações dos alunos num centro educativo. Um modelo simples, que deve ser feito para cada centro, permite facilitar o estudo e a compreensão dos primeiros rudimentos astronômicos. O modelo construído apresenta-se, por sua vez, como um modelo simples de relógio equatorial e a partir dele pode-se construir outros modelos (horizontal e vertical)

  5. Holocene vertical displacement on the central segments of the Wasatch fault zone, Utah

    USGS Publications Warehouse

    DuRoss, C.B.

    2008-01-01

    Compiled per-event vertical-displacement observations from 17 paleoseismic sites along the six central segments of the Wasatch fault zone (WFZ) highlight possible biases and trends in displacement along the fault. The displacement data are consistent with a model of characteristic-type slip, but anomalous and variable displacements indicate that significant natural variability in displacement occurs. When combined into a composite distribution of displacement, 79% of the data fit within a displacement envelope that shows displacement decreasing in a half-ellipse shape from 1.4-3.5 m near the segment centers to 0.6-2.5 m near the ends. Additionally, displacements normalized by the distance from the segment centers to ends decrease from means of 2.0-3.0 m near the segment centers to 1.3-1.9 m near the ends, consistent with characteristic-type slip termination. Although several paleoseismic sites exhibit repeated, similar displacements, the data are sparse and both low-valued (0.5-0.8 m) and high-valued (4.2-4.7 m) outliers suggest complex strain release, possibly resulting from segment interaction and/or noncharacteristic events. Although a global, normal-fault-type surface-rupture-length (SRL) average-displacement regression underpredicts observed WFZ displacements, the largest displacements per segment correspond well with a SRL maximum-displacement regression. This correlation, as well as moderate variability in SRL- and displacement-based moment magnitude, suggests that the anomalous displacements represent the intrinsic variability in characteristic displacement per segment. Thus, minor variations to the characteristic slip model to account for exceptional upper- and lower-bound displacements, e.g., a hybrid characteristic-variable slip model, may be appropriate for the WFZ. Additional paleoseismic data are necessary to address data gaps and biases, to facilitate more robust tests of earthquake-slip models, and to reduce uncertainty in SRL, displacement, and

  6. LNAPL Displacement in a Porous Medium by Flushing with a Humic Acid Solution

    NASA Astrophysics Data System (ADS)

    Steffy, D. A.

    2002-12-01

    A series of laboratory tests and numerical model simulations were conducted to evaluate the use of humic acid (HA) as a surfactant to mobilize simulate low-density, non-aqueous phase liquid (LNAPL) in a sand aquifer. The laboratory tests were conducted with homogenous fine-grained sand, packed in a 50-cm borosilicate tube with a diameter of 3 cm. The LNAPL was a mineral oil dyed with Sudan IV. The tests were initiated by establishing a water table condition in a vertical sand-packed column that becomes contaminated by the LNAPL. The column is then rotated horizontal and pumped with the surfactant at a constant rate. The amount and rate of LNAPL displaced was measured. Laboratory tests found that at higher the pump rates the more LNAPL was recovered (displaced). However, in terms of pumping efficiency (amount of LNAPL recovered / amount of fluid pumped) - a moderate pump rate of 127 cc/hr (0.6 pore volumes/hr) was the most efficient. HA at its critical micelle concentration of 3.5 mg/ml was then used to increase LNAPL mobilization. When a humic acid solution was used, recovery was increased from 60% to 81%, and efficiency was improved by over 180%. A dynamic model using STELLA software was then used to evaluate the delivery systems of surfactant and characteristics of the surfactant itself to enhance LNAPL recovery. This dynamic one-dimensional model was first calibrated using laboratory derived LNAPL displacement measurements. The calibrated model found no difference between a continuous and cyclic delivery of the surfactant.

  7. Horizontal drilling: Overview of geologic aspects and opportunities

    SciTech Connect

    Stark, P.H. )

    1991-06-01

    Horizontal drilling and completions may become the most significant petroleum technology enhancement since reflection seismic. Through September 1990, 640 US horizontal completions were recorded, resulting in 532 oil and 69 gas producers. In addition, 345 horizontal wells were drilling or completing and 255 permits were outstanding. Mroe than 60% of historic US horizontal wells will be completed during 1990. Case studies demonstrate higher production rates and improved recoveries for horizontal completions. There are abundant global geologic opportunities for horizontal well technolgoy. Eight geologic criteria with potential for horizontal technology are reviewed. Models and examples showing results are presented for each. Source rocks - Bakken Shale case history, North Dakota; Fractured reservoirs - Austin Chalk case history, Texas; Paleokarst reservoirs - Liuhua field example, South China Sea; and karst reservoir potential, Mediterranean region; Chalk reservoirs - global distribution and Niobrara example, Colorado and Wyoming; Stratigraphic traps - Niagaran Reef example, Michigan basin; and tight, overpressured gas sands, northern Rocky Mountains; Reservoir/heterogeneity - Spraberry trend example, Midland basin; Coal-bed methane - US potential; Coning - Prudhoe Bay example, Alaska. Forecasts showing 5,000 worldwide horizontal completions by the year 2000 are tempered by limited equipment, crews, and recognized opportunity. If, however, economic benefits from case histories are creatively applied to potential geologic opportunities, then horizontal technology may comprise 30% or more of worldwide drilling at the turn of the century. Certainly, a technology that reduces dry-hole and environmental risks, increases productivity, and generates profits with $20/bbl oil could revitalize the domestic onshore industry.

  8. Characteristics of On-fault and Off-fault displacement of various fault types based on numerical simulation

    NASA Astrophysics Data System (ADS)

    Inoue, N.; Kitada, N.; Takemura, K.

    2015-12-01

    There are two types of fault displacement related to the earthquake fault: on-fault displacement and off-fault displacement. Off-fault displacement should be evaluated in important facilities, such as Nuclear Installations. Probabilistic Fault Displacement Hazard Analysis (PFDHA) is developing on the basis of PSHA. PFDHA estimates on-fault and off-fault displacement. For estimation, PFDHA uses distance-displacement functions, which are constructed from field measurement data. However, observed displacement data are still sparse, especially off-fault displacement. In Nuclear Installations, estimation of off-fault displacement is more important than that of on-fault. We carried out numerical fault displacement simulations to assist in understanding distance-displacement relations of on-fault and off-fault according to fault types, normal, reverse and strike fault. We used Okada's dislocation method. The displacements were calculated based on the single fault model with several rakes of slip. On-fault displacements (along the fault profile) of each fault types show a similar trend. Off-fault displacements (cross profile to the fault) of vertical (reverse and normal) fault types show the rapid decreasing displacement on the foot wall side. In the presentation, we will show the displacement profile and also stress, strain and so on. The dislocation model can not express discontinuous displacements. In the future, we will apply various numerical simulations (Finite Element Method, Distinct Element Method) in order to evaluate off-fault displacements. We will also compare numerical simulation results with observed data.

  9. MMH fluids reduce formation damage in horizontal wells

    SciTech Connect

    Fraser, L. ); Williamson, D. ); Haydel, S. )

    1994-02-01

    It has been more than 3 years since a mixed metal hydroxide fluid was used by Texaco to drill the Gulf of Mexico's first horizontal hole. Since, the fluid has been used to drill dozens of horizontal sections worldwide, including Australia, Indonesia, CIS, UAE, UK, and in North an South America. Due to Texaco's drilling success on the first Gulf of Mexico horizontal well in 1990, several horizontal wells were drilled in the Gulf's shallow gas sands. Fluids were weighted exclusively with ground marble. The marble, with measured grind size distributions similar to commercial barite, is used as a combination weighting and bridging material and is about 99% acid soluble. Completions were carried out by running a slotted liner, displacing the mixed metal hydroxide (MMH) fluid with calcium chloride brine, and running prepacked screens. Clean-up times where short and production rates equaled or exceeded expectations. Since the technique was relatively new, no comparisons could be made. One operator, however, achieved success during 18 months of production. During this period, the fluid was also used to drill a horizontal section through the Cardium Sandstone at Lodgepole in Alberta, Canada. The fluid out-performed other in return permeability tests on cores from the reservoir. Its performance was enhanced by addition of propylene glycol. High field production rates supported laboratory findings.

  10. Polyimidazoles Via Aromatic Nucleophilic Displacement

    NASA Technical Reports Server (NTRS)

    Connell, John W.; Hergenrother, Paul M.

    1990-01-01

    Experiments show variety of polyimidazoles prepared by aromatic nucleophilic displacement, from reactions of bisphenol imidazoles with activated difluoro compounds. Polyimidazoles have good mechanical properties making them suitable for use as films, moldings, and adhesives.

  11. Displacement sensing system and method

    DOEpatents

    VunKannon, Jr., Robert S

    2006-08-08

    A displacement sensing system and method addresses demanding requirements for high precision sensing of displacement of a shaft, for use typically in a linear electro-dynamic machine, having low failure rates over multi-year unattended operation in hostile environments. Applications include outer space travel by spacecraft having high-temperature, sealed environments without opportunity for servicing over many years of operation. The displacement sensing system uses a three coil sensor configuration, including a reference and sense coils, to provide a pair of ratio-metric signals, which are inputted into a synchronous comparison circuit, which is synchronously processed for a resultant displacement determination. The pair of ratio-metric signals are similarly affected by environmental conditions so that the comparison circuit is able to subtract or nullify environmental conditions that would otherwise cause changes in accuracy to occur.

  12. Genome-Wide Molecular Clock and Horizontal Gene Transfer in Bacterial Evolution

    PubMed Central

    Novichkov, Pavel S.; Omelchenko, Marina V.; Gelfand, Mikhail S.; Mironov, Andrei A.; Wolf, Yuri I.; Koonin, Eugene V.

    2004-01-01

    We describe a simple theoretical framework for identifying orthologous sets of genes that deviate from a clock-like model of evolution. The approach used is based on comparing the evolutionary distances within a set of orthologs to a standard intergenomic distance, which was defined as the median of the distribution of the distances between all one-to-one orthologs. Under the clock-like model, the points on a plot of intergenic distances versus intergenomic distances are expected to fit a straight line. A statistical technique to identify significant deviations from the clock-like behavior is described. For several hundred analyzed orthologous sets representing three well-defined bacterial lineages, the α-Proteobacteria, the γ-Proteobacteria, and the Bacillus-Clostridium group, the clock-like null hypothesis could not be rejected for ∼70% of the sets, whereas the rest showed substantial anomalies. Subsequent detailed phylogenetic analysis of the genes with the strongest deviations indicated that over one-half of these genes probably underwent a distinct form of horizontal gene transfer, xenologous gene displacement, in which a gene is displaced by an ortholog from a different lineage. The remaining deviations from the clock-like model could be explained by lineage-specific acceleration of evolution. The results indicate that although xenologous gene displacement is a major force in bacterial evolution, a significant majority of orthologous gene sets in three major bacterial lineages evolved in accordance with the clock-like model. The approach described here allows rapid detection of deviations from this mode of evolution on the genome scale. PMID:15375139

  13. Structural analysis of Niobe Planitia, Venus: Evidence of lateral lithospheric displacement.

    NASA Astrophysics Data System (ADS)

    Romeo, I.; Capote, R.; Anguita, F.

    Structural analysis of Niobe Planitia, Venus: Evidence of lateral lithospheric displacement. I. Romeo (1), R. Capote (1) and F. Anguita (2) (1) Universidad Complutense de Madrid, Departamento de Geodinámica, 28040 Madrid, Spain, (2) Universidad Complutense de Madrid, Departamento de Petrología y Geoquímica, 28040 Madrid, Spain (iromeobr@geo.ucm.es / Phone: +34 91 3944864) Structural analysis of Niobe Planitia (15o - 40o N, 100o - 130o E) has yielded a tectonic pattern evidencing horizontal lithospheric movement. This lateral movement was accommodated by generating different deformation belts. The deformation belt kinematics is controlled by the orientation of each belt in respect to the direction of lithospheric displacement. Uni Dorsa, located in the NE limit of the study area, is the main feature that accommodated the lateral lithospheric displacement. It presents folds with a wide range of wavelengths from 150 km to 250 m. This compressive deformation belt crosses Niobe Planitia describing an arc oriented with a SE strike in the northern area rotating to a ESE strike in its southern termination. The northern part (SE strike) of Uni Dorsa is characterized by coaxial deformation, developing folds parallel to the belt strike, however the southern part (ESE strike) of Uni Dorsa reveals evidence of non-coaxial deformation, showing S-C structures from which can be deduced a transpressional sinistral kinematics. Other deformation belt is developed from the southern termination of Uni Dorsa towards the south with a SSW strike. This deformation belt is more diffuse, featuring en echelon right-stepped folds that can be interpreted as caused by a dextral transpresional tectonic regime. The tectonic pattern is completed by large lineaments parallel to the belt strike, interpreted as dextral strike slip faults. The kinematic study of these deformation belts reveals a constant NE shortening direction that we interpret as the direction of approximation of western Niobe

  14. A novel linear displacement sensor

    NASA Astrophysics Data System (ADS)

    Yang, Ji-sen; Zhang, Jing; Chen, Xi-hou; Zhang, Tian-heng

    2011-12-01

    With development of time grating technology in the past 10 years, the theory of using time to measure spatial displacement has been completed greatly. In the study of time grating, one novel linear displacement sensor is proposed based on the measurement principles of time grating. The measurement principles of linear displacement are similar to that of angular displacement. Both of them need one endless coordinate with uniform velocity. The theory of linear AC motor is used, and the three-phase winding with equal division space of 120° and three-phase exciting signal with uniform time are utilized to generate the endless moving coordinate with uniform velocity. The magnetic traveling wave arises from the left endpoint and disappears in the right endpoint, and it travels pole pitch distance of W during the periodic time of T with the uniform velocity. When magnetic traveling wave passes by the static probe and the moving probe, the electric signals will be induced on the winding, respectively. Therefore, the linear displacement can be achieved by comparing the phase between the two output induced signals from he static probe and the moving probe. Furthermore, in order to improve the machining technique, four kinds of winding framework are designed to employ. The experimental results show that advantages and disadvantages both exist in the design methods and the precision of experiment results reaches +/-2µm. The next study plan is to choose the most excellent design method through further experiments and improve the precision of displacement sensor greatly.

  15. Correlation Tests of the Ditching Behavior of an Army B-24D Airplane and a 1/16-size Model

    NASA Technical Reports Server (NTRS)

    Jarvis, George A.; Fisher, Lloyd J.

    1946-01-01

    Behaviors of both model and full-scale airplanes were ascertained by making visual observations, by recording time histories of decelerations, and by taking motion picture records of ditchings. Results are presented in form of sequence photographs and time-history curves for attitudes, vertical and horizontal displacements, and longitudinal decelerations. Time-history curves for attitudes and horizontal and vertical displacements for model and full-scale tests were in agreement; maximum longitudinal decelerations for both ditchings did not occur at same part of run; full-scale maximum deceleration was 50 percent greater.

  16. The Effect of Basepair Mismatch on DNA Strand Displacement.

    PubMed

    Broadwater, D W Bo; Kim, Harold D

    2016-04-12

    DNA strand displacement is a key reaction in DNA homologous recombination and DNA mismatch repair and is also heavily utilized in DNA-based computation and locomotion. Despite its ubiquity in science and engineering, sequence-dependent effects of displacement kinetics have not been extensively characterized. Here, we measured toehold-mediated strand displacement kinetics using single-molecule fluorescence in the presence of a single basepair mismatch. The apparent displacement rate varied significantly when the mismatch was introduced in the invading DNA strand. The rate generally decreased as the mismatch in the invader was encountered earlier in displacement. Our data indicate that a single base pair mismatch in the invader stalls branch migration and displacement occurs via direct dissociation of the destabilized incumbent strand from the substrate strand. We combined both branch migration and direct dissociation into a model, which we term the concurrent displacement model, and used the first passage time approach to quantitatively explain the salient features of the observed relationship. We also introduce the concept of splitting probabilities to justify that the concurrent model can be simplified into a three-step sequential model in the presence of an invader mismatch. We expect our model to become a powerful tool to design DNA-based reaction schemes with broad functionality. PMID:27074674

  17. Understanding inter-annual displacements associated to loading in Southern Europe using geodetic techniques

    NASA Astrophysics Data System (ADS)

    Valty, P.; de Viron, O.; Panet, I.

    2012-12-01

    Over the last decades, the number and diversity of geodetic measurements has kept growing, now providing long time series of precise and independent measurements. Since 2002, the GRACE mission has been measuring the Earth's gravity field temporal variations, which are dominated by mass transfers associated to the water cycle. These water mass variations also cause the Earth's surface to deform, impacting the time series of horizontal or vertical displacements measured by GPS. Because they sense the total water content, from the surface to the depth, over long time spans, geodetic data provide unique information, that can improve our understanding of the water resources variations and how they are influenced by climate variations. In this context, we analyze the inter-annual variability common to GRACE, GPS and the loading models over Southern Europe, where a dense network of GPS permanent stations is available. First, we convert the GRACE geoids into their associated displacements and then, we isolate common inter-annual variability modes with the GPS data and the loading models by applying a Singular Value Decomposition (SVD). When analysing the spatial and temporal characteristics of these modes, we evidence the signature of extreme climatic events like the heatwaves of 2003 and 2007. We finally discuss these results in terms of hydrological signal and investigate the specific signature of the noticed critic climatic events in the geodetic time series.

  18. Horizontal and Vertical Line Designs.

    ERIC Educational Resources Information Center

    Johns, Pat

    2003-01-01

    Presents an art lesson in which students learn about the artist Piet Mondrian and create their own abstract artworks. Focuses on geometric shapes using horizontal and vertical lines. Includes background information about the artist. (CMK)

  19. Retrieving real-time precise co-seismic displacements with a standalone single-frequency GPS receiver

    NASA Astrophysics Data System (ADS)

    Chen, Kejie; Ge, Maorong; Li, Xingxing; Babeyko, Andrey; Ramatschi, Markus; Bradke, Markus

    2015-08-01

    Nowadays, Global Positioning System (GPS) plays an increasingly important role in retrieving real-time precise co-seismic displacements for geo-hazard monitoring and early warning. Several real-time positioning approaches have been demonstrated for such purpose, such as real-time kinematic relative positioning, precise point positioning, etc., where dual-frequency geodetic receivers are applied for the removal of ionosphere delays by inter-frequency combination. At the same time, it would be also useful to develop efficient algorithms for estimating precise displacements with low-cost GPS receivers since they can make a denser network or multi-sensors combination without putting too much financial burden. In this contribution, we present a new method to retrieve precise co-seismic displacements in real-time using a standalone single-frequency receiver. In the new method, observations prior to an earthquake are utilized to establish a precise ionospheric delay prediction model, so that precise co-seismic displacements can be obtained without any convergence process. Our method was validated with an outdoor experiment as well as by re-processing of 1-Hz GPS data collected by the GEONET network during the 2011 Tohoku Mw 9.0 earthquake. For the latter, RMS against dual-frequency receivers constituted 2 cm for horizontal components and 3 cm for the vertical component. We specially address the observation biases and their impact on the accuracy of single frequency positioning. Our approach makes real-time GPS displacement monitoring with dense network much more affordable in terms of financial costs.

  20. Case history of an opposed-bore, dual horizontal well in the Austin Chalk formation of south Texas

    SciTech Connect

    Cooney, M.F.; Rogers, C.T.; Stacey, E.S.; Stephens, R.N.

    1993-03-01

    Petro-Hunt Corp. used a unique horizontal-well design to optimize development of an irregularly shaped lease in the Austin chalk formation in Texas. Two medium-radius horizontal bores were drilled in opposite directions from one vertical hole to maximize horizontal displacement in the lease. Underbalanced drilling techniques were used to prevent formation damage. The well design resulted in a significant cost savings per horizontal foot compared with 24 offset wells that the operator drilled. This paper reviews well planning and drilling and emphasizes techniques used to intersect thin horizontal targets and to initiate the second horizontal bore. Production results and drilling economics are discussed briefly, and ideas on future dual-horizontal-well applications are presented.

  1. Transducer of linear displacements

    NASA Astrophysics Data System (ADS)

    Malamed, Y. R.

    1984-02-01

    The basic PLP transducer is designed for a UIM-29 microscope and a 2-coordinate measuring instrument with electronic digital readout. Its optical system consists of an AL-107B light-emitting diode as light source, two condenser lenses, a special wedge carrying two pairs of joined receiver lenses, a prism-mirror, a photoreceiver, a wedge-shape transparent replica of a twin diffraction grating which prevents light reflected by the air-glass interface from focusing on the receiver photodiodes, and a reflective replica of a diffraction grating on a movable carriage. The already available three models of this transducer are PLP1-0.2, PLP1-0.5, and PLP1-1.0 with respectively 625, 250, 125 lines/mm on the transparent replica and respectively 312.5, 125, 62.5 lines/mm on the reflective replica. The scale of moire-interference fringes characterizing the shift between both diffraction gratings per grating period (9.16 mm in each model) is respectively 0.8, 2.0, 4.0 microns and the angle between the two arrays of grating lines on the transparent replica is respectively 36 + or - 4 deg, 90 + or - 10 deg, 190 + or - 20 deg.

  2. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy

    PubMed Central

    Monzel, C.; Schmidt, D.; Kleusch, C.; Kirchenbüchler, D.; Seifert, U.; Smith, A-S; Sengupta, K.; Merkel, R.

    2015-01-01

    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living cells was limited due to a lack of tools to accurately record them. Here we introduce a novel technique—dynamic optical displacement spectroscopy (DODS), to measure stochastic displacements of membranes with unprecedented combined spatiotemporal resolution of 20 nm and 10 μs. The technique was validated by measuring bending fluctuations of model membranes. DODS was then used to explore the fluctuations in human red blood cells, which showed an ATP-induced enhancement of non-Gaussian behaviour. Plasma membrane fluctuations of human macrophages were quantified to this accuracy for the first time. Stimulation with a cytokine enhanced non-Gaussian contributions to these fluctuations. Simplicity of implementation, and high accuracy make DODS a promising tool for comprehensive understanding of stochastic membrane processes. PMID:26437911

  3. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy.

    PubMed

    Monzel, C; Schmidt, D; Kleusch, C; Kirchenbüchler, D; Seifert, U; Smith, A-S; Sengupta, K; Merkel, R

    2015-01-01

    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living cells was limited due to a lack of tools to accurately record them. Here we introduce a novel technique--dynamic optical displacement spectroscopy (DODS), to measure stochastic displacements of membranes with unprecedented combined spatiotemporal resolution of 20 nm and 10 μs. The technique was validated by measuring bending fluctuations of model membranes. DODS was then used to explore the fluctuations in human red blood cells, which showed an ATP-induced enhancement of non-Gaussian behaviour. Plasma membrane fluctuations of human macrophages were quantified to this accuracy for the first time. Stimulation with a cytokine enhanced non-Gaussian contributions to these fluctuations. Simplicity of implementation, and high accuracy make DODS a promising tool for comprehensive understanding of stochastic membrane processes. PMID:26437911

  4. Measuring fast stochastic displacements of bio-membranes with dynamic optical displacement spectroscopy

    NASA Astrophysics Data System (ADS)

    Monzel, C.; Schmidt, D.; Kleusch, C.; Kirchenbüchler, D.; Seifert, U.; Smith, A.-S.; Sengupta, K.; Merkel, R.

    2015-10-01

    Stochastic displacements or fluctuations of biological membranes are increasingly recognized as an important aspect of many physiological processes, but hitherto their precise quantification in living cells was limited due to a lack of tools to accurately record them. Here we introduce a novel technique--dynamic optical displacement spectroscopy (DODS), to measure stochastic displacements of membranes with unprecedented combined spatiotemporal resolution of 20 nm and 10 μs. The technique was validated by measuring bending fluctuations of model membranes. DODS was then used to explore the fluctuations in human red blood cells, which showed an ATP-induced enhancement of non-Gaussian behaviour. Plasma membrane fluctuations of human macrophages were quantified to this accuracy for the first time. Stimulation with a cytokine enhanced non-Gaussian contributions to these fluctuations. Simplicity of implementation, and high accuracy make DODS a promising tool for comprehensive understanding of stochastic membrane processes.

  5. The Computational Fluid Dynamic (CFD) Modeling of the Horizontal Single Belt Casting (HSBC) Processing of Al-Mg-Sc-Zr Alloy Strips

    NASA Astrophysics Data System (ADS)

    Ge, S.; Isac, M.; Guthrie, R. I. L.

    2015-10-01

    Al-Mg-Sc-Zr alloys have shown exceptional potential as structural materials for transportation applications. These alloys have proved to be good candidates to be processed as thin strips via the horizontal single belt casting (HSBC) process. The HSBC process is a near-net-shape casting technology, which involves casting molten metal directly into thin strips, close to the final product thickness, at higher cooling rates than conventional continuous casting and thin-slab casting processes. It offers an efficient, economical, and environmentally friendly approach to the production of metal strips. Fluid mechanics and associated heat transfer are important aspects of any casting process, and the novel HSBC process is no exception. Three-dimensional computational fluid dynamics simulations using ANSYS FLUENT 14.5 were performed, in order to assess the importance and effects of the various operational conditions of the HSBC process. This enabled process parameter optimization. Numerical predictions were validated against experimental casting results.

  6. Natural convection in a horizontal cylindrical annulus filled with a porous medium saturated by a nanofluid using Tiwari and Das' nanofluid model

    NASA Astrophysics Data System (ADS)

    Sheremet, M. A.; Pop, Ioan

    2015-06-01

    This paper deals with a numerical study of natural convection flow and heat transfer inside a concentric horizontal annulus filled with a porous medium saturated by a cuprum (Cu)-water nanofluid. The inner and outer cylinders are kept at different constant temperatures. First, the governing partial differential equations in dimensional formulation in a polar coordinate system for the physical domain are transformed in dimensionless form in terms of stream function-temperature formulation. These equations along with the corresponding boundary conditions were solved numerically by the finite difference method. Particular efforts have been focused on the effects of the Rayleigh number, porosity of the porous medium, solid volume fraction parameter of nanoparticles, annulus radius ratio, and the solid matrix of the porous medium (glass balls and aluminum foam) on the local and average Nusselt numbers, streamlines and isotherms. It is found that a very good agreement exists between the present results and those from the open literature.

  7. Job Displacement Among Single Mothers:

    PubMed Central

    Brand, Jennie E.; Thomas, Juli Simon

    2015-01-01

    Given the recent era of economic upheaval, studying the effects of job displacement has seldom been so timely and consequential. Despite a large literature associating displacement with worker well-being, relatively few studies focus on the effects of parental displacement on child well-being, and fewer still focus on implications for children of single parent households. Moreover, notwithstanding a large literature on the relationship between single motherhood and children’s outcomes, research on intergenerational effects of involuntary employment separations among single mothers is limited. Using 30 years of nationally representative panel data and propensity score matching methods, we find significant negative effects of job displacement among single mothers on children’s educational attainment and social-psychological well-being in young adulthood. Effects are concentrated among older children and children whose mothers had a low likelihood of displacement, suggesting an important role for social stigma and relative deprivation in the effects of socioeconomic shocks on child well-being. PMID:25032267

  8. Uniform head in horizontal and vertical wells.

    PubMed

    Steward, David R; Jin, Wei

    2006-01-01

    The steady-state head within a fully penetrating well may be estimated by evaluating the Thiem equation at the radius of the well. A method is presented here to extend results from the Thiem equation to horizontal wells and to partially penetrating wells. The particular model used in this investigation is based upon the analytic element method; it accurately reproduces a boundary condition of uniform head along the cylindrical surface at the perforated face of the well. This model is exercised over a representative range of parameters including the well's length, radius, and pumping rate, and the aquifer's hydraulic conductivity and thickness. Results are presented in a set of figures and tables that compare the well's drawdown to the drawdown that would have been obtained using the Thiem solution with the same pumping rate and radius. A methodology is presented to estimate the head within a horizontal or partially penetrating well by adding a correction term to results that can be readily obtained from computer models of vertical fully penetrating wells. This approach may also be used to contrast the differences in head between horizontal and vertical wells of various lengths, radii, and placement elevations. PMID:16405471

  9. Modeling and inversion of volcanic surface deformation based on Mogi model and McTigue model

    NASA Astrophysics Data System (ADS)

    Srigutomo, Wahyu; Trimadona, Martakusumah, Rocky; Anwar, Hairil

    2015-04-01

    Surface deformation occurred in a volcano is related strongly to the magmatic deformation beneath it. In this work we calculate the surface vertical and horizontal displacements due to hydrostatic pressure change of magma cavity based on point pressure source (Mogi) model and finite spherical source (McTigue) model. We apply the Levenberg-Marquardt inversion scheme to esti