Science.gov

Sample records for accurate experimental results

  1. SAA drift: Experimental results

    NASA Astrophysics Data System (ADS)

    Grigoryan, O. R.; Romashova, V. V.; Petrov, A. N.

    According to the paleomagnetic analysis there are variations of Earth’s magnetic field connected with magnetic moment changing. These variations affect on the South Atlantic Anomaly (SAA) location. Indeed different observations approved the existence of the SAA westward drift rate (0.1 1.0 deg/year) and northward drift rate (approximately 0.1 deg/year). In this work, we present the analysis of experimental results obtained in Scobeltsyn Institute of Nuclear Physics, Moscow State University (SINP MSU) onboard different Earth’s artificial satellites (1972 2003). The fluxes of protons with energy >50 MeV, gamma quanta with energy >500 keV and neutrons with energy 0.1 1.0 MeV in the SAA region have been analyzed. The mentioned above experimental data were obtained onboard the orbital stations Salut-6 (1979), MIR (1991, 1998) and ISS (2003) by the similar experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact that the SAA drifts westward. Moreover the analysis of fluxes of electrons with energy about hundreds keV (Cosmos-484 (1972) and Active (Interkosmos-24, 1991) satellites) verified not only the SAA westward drift but northward drift also.

  2. Accurate stress resultants equations for laminated composite deep thick shells

    SciTech Connect

    Qatu, M.S.

    1995-11-01

    This paper derives accurate equations for the normal and shear force as well as bending and twisting moment resultants for laminated composite deep, thick shells. The stress resultant equations for laminated composite thick shells are shown to be different from those of plates. This is due to the fact the stresses over the thickness of the shell have to be integrated on a trapezoidal-like shell element to obtain the stress resultants. Numerical results are obtained and showed that accurate stress resultants are needed for laminated composite deep thick shells, especially if the curvature is not spherical.

  3. PDX experimental results

    SciTech Connect

    Meade, D.; Arunasalam, V.; Barnes, C.

    1981-01-01

    The main objectives of the Poloidal Divertor Experiment (PDX) are to: (1) determine the effectiveness of poloidal divertors in controlling impurities in high temperature plasmas, (2) use the poloidal divertor to provide clean plasmas for confinement and high beta studies, and (3) investigate the effect of cross-section shaping on plasma confinement and MHD properties. In this paper, we report the results obtained during initial divertor operation of the PDX.

  4. Accurate theoretical and experimental characterization of optical grating coupler.

    PubMed

    Fesharaki, Faezeh; Hossain, Nadir; Vigne, Sebastien; Chaker, Mohamed; Wu, Ke

    2016-09-01

    Periodic structures, acting as reflectors, filters, and couplers, are a fundamental building block section in many optical devices. In this paper, a three-dimensional simulation of a grating coupler, a well-known periodic structure, is conducted. Guided waves and leakage characteristics of an out-of-plane grating coupler are studied in detail, and its coupling efficiency is examined. Furthermore, a numerical calibration analysis is applied through a commercial software package on the basis of a full-wave finite-element method to calculate the complex propagation constant of the structure and to evaluate the radiation pattern. For experimental evaluation, an optimized grating coupler is fabricated using electron-beam lithography technique and plasma etching. An excellent agreement between simulations and measurements is observed, thereby validating the demonstrated method. PMID:27607706

  5. SAA drift:experimental results

    NASA Astrophysics Data System (ADS)

    Grigoryan, O. R.; Kudela, K.; Romashova, V. V.; Drozdov, A. Yu.

    According to the paleomagnetic analysis there are variations of Earth's magnetic field connected with magnetic momentum changing. Besides these variations affects on the trapped belt South Atlantic Anomaly (SAA) location. Indeed different observations including Space Shuttle short-time flights approved the existence SAA westward drift with speed 0.1-1.0 (deg/year) and northward drift with speed approximately 0.1 (deg/year). In this work we present the analysis of experimental results obtained in SINP MSU in 1972-2003 from different satellites. There were analyzed the fluxes of protons with energy > 50 MeV, gamma quanta with energy > 500 keV and neutrons with energy 0.1-1.0 MeV in SAA area and their maxima location. The data about fluxes were obtained onboard the orbital stations ``Salut-6'' (1979), MIR (1991, 1998) and ISS (2003) by the identical experimental equipment. The comparison of the data obtained during these two decades of investigations confirms the fact of the SAA westward drift. Moreover the same analysis of maximum flux location of electrons with hundreds keV energy (satellites ``Kosmos-484'' (1972), ``Interkosmos-17'' (1977) and ``Activny'' (``Interkosmos-24'', 1991)) confirmed not only the SAA westward drift but northward drift also.

  6. Majorana Thermosyphon Prototype Experimental Results

    SciTech Connect

    Fast, James E.; Reid, Douglas J.; Aguayo Navarrete, Estanislao

    2010-12-17

    Objective The Majorana demonstrator will operate at liquid Nitrogen temperatures to ensure optimal spectrometric performance of its High Purity Germanium (HPGe) detector modules. In order to transfer the heat load of the detector module, the Majorana demonstrator requires a cooling system that will maintain a stable liquid nitrogen temperature. This cooling system is required to transport the heat from the detector chamber outside the shield. One approach is to use the two phase liquid-gas equilibrium to ensure constant temperature. This cooling technique is used in a thermosyphon. The thermosyphon can be designed so the vaporization/condensing process transfers heat through the shield while maintaining a stable operating temperature. A prototype of such system has been built at PNNL. This document presents the experimental results of the prototype and evaluates the heat transfer performance of the system. The cool down time, temperature gradient in the thermosyphon, and heat transfer analysis are studied in this document with different heat load applied to the prototype.

  7. Accurate Navier-Stokes results for the hypersonic flow over a spherical nosetip

    SciTech Connect

    Blottner, F.G.

    1989-01-01

    The unsteady thin-layer Navier-Stokes equations for a perfect gas are solved with a linearized block Alternating Direction Implicit finite-difference solution procedure. Solution errors due to numerical dissipation added to the governing equations are evaluated. Errors in the numerical predictions on three different grids are determined where Richardson extrapolation is used to estimate the exact solution. Accurate computational results are tabulated for the hypersonic laminar flow over a spherical body which can be used as a benchmark test case. Predictions obtained from the code are in good agreement with inviscid numerical results and experimental data. 9 refs., 11 figs., 3 tabs.

  8. Pentaquarks: the latest experimental results

    SciTech Connect

    M. Battaglieri; R. De Vita; Valery Kubarovsky

    2006-01-01

    After the claim of the possible discovery of a pentaquark state, many experiments reported positive and negative results opening a discussion about the pentaquark existence. New experiments with high resolution and high statistics are needed in the reaction channels and for the kinematics of the positive results to solve the controversy. Jefferson Lab started a comprehensive program to search for pentaquark in photoproduction at threshold on proton and deuteron targets, collecting more than 10 times the existing statistics. The first experiment on the proton (g11) just finished to analyze the data, and the first results of the pentaquark search are reported here.

  9. Identification and Evaluation of Reference Genes for Accurate Transcription Normalization in Safflower under Different Experimental Conditions

    PubMed Central

    Li, Dandan; Hu, Bo; Wang, Qing; Liu, Hongchang; Pan, Feng; Wu, Wei

    2015-01-01

    Safflower (Carthamus tinctorius L.) has received a significant amount of attention as a medicinal plant and oilseed crop. Gene expression studies provide a theoretical molecular biology foundation for improving new traits and developing new cultivars. Real-time quantitative PCR (RT-qPCR) has become a crucial approach for gene expression analysis. In addition, appropriate reference genes (RGs) are essential for accurate and rapid relative quantification analysis of gene expression. In this study, fifteen candidate RGs involved in multiple metabolic pathways of plants were finally selected and validated under different experimental treatments, at different seed development stages and in different cultivars and tissues for real-time PCR experiments. These genes were ABCS, 60SRPL10, RANBP1, UBCL, MFC, UBCE2, EIF5A, COA, EF1-β, EF1, GAPDH, ATPS, MBF1, GTPB and GST. The suitability evaluation was executed by the geNorm and NormFinder programs. Overall, EF1, UBCE2, EIF5A, ATPS and 60SRPL10 were the most stable genes, and MBF1, as well as MFC, were the most unstable genes by geNorm and NormFinder software in all experimental samples. To verify the validation of RGs selected by the two programs, the expression analysis of 7 CtFAD2 genes in safflower seeds at different developmental stages under cold stress was executed using different RGs in RT-qPCR experiments for normalization. The results showed similar expression patterns when the most stable RGs selected by geNorm or NormFinder software were used. However, the differences were detected using the most unstable reference genes. The most stable combination of genes selected in this study will help to achieve more accurate and reliable results in a wide variety of samples in safflower. PMID:26457898

  10. Turtle utricle dynamic behavior using a combined anatomically accurate model and experimentally measured hair bundle stiffness

    PubMed Central

    Davis, J.L.; Grant, J.W.

    2014-01-01

    Anatomically correct turtle utricle geometry was incorporated into two finite element models. The geometrically accurate model included appropriately shaped macular surface and otoconial layer, compact gel and column filament (or shear) layer thicknesses and thickness distributions. The first model included a shear layer where the effects of hair bundle stiffness was included as part of the shear layer modulus. This solid model’s undamped natural frequency was matched to an experimentally measured value. This frequency match established a realistic value of the effective shear layer Young’s modulus of 16 Pascals. We feel this is the most accurate prediction of this shear layer modulus and fits with other estimates (Kondrachuk, 2001b). The second model incorporated only beam elements in the shear layer to represent hair cell bundle stiffness. The beam element stiffness’s were further distributed to represent their location on the neuroepithelial surface. Experimentally measured striola hair cell bundles mean stiffness values were used in the striolar region and the mean extrastriola hair cell bundles stiffness values were used in this region. The results from this second model indicated that hair cell bundle stiffness contributes approximately 40% to the overall stiffness of the shear layer– hair cell bundle complex. This analysis shows that high mass saccules, in general, achieve high gain at the sacrifice of frequency bandwidth. We propose the mechanism by which this can be achieved is through increase the otoconial layer mass. The theoretical difference in gain (deflection per acceleration) is shown for saccules with large otoconial layer mass relative to saccules and utricles with small otoconial layer mass. Also discussed is the necessity of these high mass saccules to increase their overall system shear layer stiffness. Undamped natural frequencies and mode shapes for these sensors are shown. PMID:25445820

  11. Selectivity and the production of experimental results.

    NASA Astrophysics Data System (ADS)

    Franklin, A.

    1998-12-01

    The author studies possible relations between the application of selection criteria in analyzing and interpreting the results of physical experiments and the mental preconceptions and expectations of the experimenters. He presents a detailed account of five famous cases of purported experimental results and the controversies following their publication. These cases include Joseph Weber's 1969 claim to have detected gravitational radiation - possibly originating in the center of the Milky Way, and the controversy arising from the 1985 "detection" of the 17 keV (heavy) neutrino by Simpson. Extensive bibliographical references are given for each case.

  12. Experimental Results in DIS from Jefferson Laboratory

    SciTech Connect

    Sebastian Kuhn

    2009-10-01

    We are summarizing the experimental program of Jefferson Lab (Thomas Jefferson National Accelerator Facility in Newport News, VA) in deep inelastic electron scattering. We show recent results and discuss future plans for both the present 6 GeV era and the 12 GeV energy-upgraded facility.

  13. Microwave radiometry for humanitarian demining: experimental results

    NASA Astrophysics Data System (ADS)

    Johnson, Joel T.; Kim, Hyunjin; Wiggins, David R.; Cheon, Yonghun

    2002-08-01

    Previous modeling studies have indicated that a multi-frequency radiometer could prove advantageous for humanitarian demining due to the oscillatory patterns in brightness temperature versus frequency that would be observed in the presence of a sub-surface target. Initial experimental results are reported in this paper from a multi-frequency radiometer (MFRAD) system operating at 19 frequencies in the 2.1-6.5 GHz band. The basic design of MFRAD is reviewed, and the calibration and noise background removal procedures discussed. Experimental results with sub-surface metallic and styrofoam targets are then provided that demonstrate the predicted oscillatory behavior. An FFT-based detection algorithm is also described and applied to measured data. Further plans for experiments and tests with this system are also detailed.

  14. PDX experimental results in FY82

    SciTech Connect

    Kaye, S.M.; Bell, M.; Bol, K.; Bitter, M.; Buchenauer, D.; Budny, R.; Brau, K.; Crowley, T.; Davis, S.; Dylla, H.

    1983-08-01

    This report presents a detailed summary of the major experimental results of PDX in FY82 and represents the efforts of the entire PDX group. Topics covered include ..beta..-scaling and fishbone studies, fluctuations, disruptions, impurities and impurity transport, power handling, limiter conditioning, edge studies, plasma fueling, counter-injection, and diagnostic development. A less detailed version will appear as the FY82 PDX contribution to the PPPL Annual Report.

  15. Experimental Results for Space-Wire-D

    NASA Astrophysics Data System (ADS)

    Parkes, Steve; Gibson, David; Ferrer, Albert

    2015-09-01

    SpaceWire-D is a deterministic extension to SpaceWire that uses time-division multiplexing to schedule traffic within time-slots. It allows a single SpaceWire network to be used for both time-critical avionics control applications and asynchronous payload data-handling simultaneously using existing SpaceWire technology. In this paper we describe the services of SpaceWire-D and present experimental results for each service.

  16. Recent Results on the Accurate Measurements of the Dielectric Constant of Seawater at 1.413GHZ

    NASA Technical Reports Server (NTRS)

    Lang, R.H.; Tarkocin, Y.; Utku, C.; Le Vine, D.M.

    2008-01-01

    Measurements of the complex. dielectric constant of seawater at 30.00 psu, 35.00 psu and 38.27 psu over the temperature range from 5 C to 3 5 at 1.413 GHz are given and compared with the Klein-Swift results. A resonant cavity technique is used. The calibration constant used in the cavity perturbation formulas is determined experimentally using methanol and ethanediol (ethylene glycol) as reference liquids. Analysis of the data shows that the measurements are accurate to better than 1.0% in almost all cases studied.

  17. Accurate Analytic Results for the Steady State Distribution of the Eigen Model

    NASA Astrophysics Data System (ADS)

    Huang, Guan-Rong; Saakian, David B.; Hu, Chin-Kun

    2016-04-01

    Eigen model of molecular evolution is popular in studying complex biological and biomedical systems. Using the Hamilton-Jacobi equation method, we have calculated analytic equations for the steady state distribution of the Eigen model with a relative accuracy of O(1/N), where N is the length of genome. Our results can be applied for the case of small genome length N, as well as the cases where the direct numerics can not give accurate result, e.g., the tail of distribution.

  18. Fuel-rich, catalytic reaction experimental results

    NASA Technical Reports Server (NTRS)

    Rollbuhler, R. James

    1991-01-01

    Future aeropropulsion gas turbine combustion requirements call for operating at very high inlet temperatures, pressures, and large temperature rises. At the same time, the combustion process is to have minimum pollution effects on the environment. Aircraft gas turbine engines utilize liquid hydrocarbon fuels which are difficult to uniformly atomize and mix with combustion air. An approach for minimizing fuel related problems is to transform the liquid fuel into gaseous form prior to the completion of the combustion process. Experimentally obtained results are presented for vaporizing and partially oxidizing a liquid hydrocarbon fuel into burnable gaseous components. The presented experimental data show that 1200 to 1300 K reaction product gas, rich in hydrogen, carbon monoxide, and light-end hydrocarbons, is formed when flowing 0.3 to 0.6 fuel to air mixes through a catalyst reactor. The reaction temperatures are kept low enough that nitrogen oxides and carbon particles (soot) do not form. Results are reported for tests using different catalyst types and configurations, mass flowrates, input temperatures, and fuel to air ratios.

  19. Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis

    NASA Astrophysics Data System (ADS)

    Gabriele, Papadia; Antonio, Del Prete; Alfredo, Anglani

    2010-06-01

    The increasing application of numerical simulation in metal forming field has helped engineers to solve problems one after another to manufacture a qualified formed product reducing the required time [1]. Accurate simulation results are fundamental for the tooling and the product designs. The wide application of numerical simulation is encouraging the development of highly accurate simulation procedures to meet industrial requirements. Many factors can influence the final simulation results and many studies have been carried out about materials [2], yield criteria [3] and plastic deformation [4,5], process parameters [6] and their optimization. In order to develop a reliable hydromechanical deep drawing (HDD) numerical model the authors have been worked out specific activities based on the evaluation of the effective stiffness of the blankholder structure [7]. In this paper after an appropriate tuning phase of the blankholder force distribution, the experimental activity has been taken into account to improve the accuracy of the numerical model. In the first phase, the effective capability of the blankholder structure to transfer the applied load given by hydraulic actuators to the blank has been explored. This phase ended with the definition of an appropriate subdivision of the blankholder active surface in order to take into account the effective pressure map obtained for the given loads configuration. In the second phase the numerical results obtained with the developed subdivision have been compared with the experimental data of the studied model. The numerical model has been then improved, finding the best solution for the blankholder force distribution.

  20. Material response mechanisms are needed to obtain highly accurate experimental shock wave data

    NASA Astrophysics Data System (ADS)

    Forbes, Jerry

    2015-06-01

    The field of shock wave compression of matter has provided a simple set of equations relating thermodynamic and kinematic parameters that describe the conservation of mass, momentum and energy across a steady shock wave with one-dimensional flow. Well-known condensed matter shock wave experimental results will be reviewed to see whether the assumptions required for deriving these simple R-H equations are met. Note that the material compression model is not required for deriving the 1-D conservation flow equations across a steady shock front. However, this statement is misleading from a practical experimental viewpoint since obtaining small systematic errors in shock wave measured parameters requires the material compression and release mechanisms to be known. A brief review will be presented on systematic errors in shock wave data from common experimental techniques for fluids, elastic-plastic solids, materials with negative volume phase transitions, glass and ceramic materials, and high explosives. Issues related to time scales of experiments and quasi-steady flow will also be presented.

  1. Superspreading: molecular dynamics simulations and experimental results

    NASA Astrophysics Data System (ADS)

    Theodorakis, Panagiotis; Kovalchuk, Nina; Starov, Victor; Muller, Erich; Craster, Richard; Matar, Omar

    2015-11-01

    The intriguing ability of certain surfactant molecules to drive the superspreading of liquids to complete wetting on hydrophobic substrates is central to numerous applications that range from coating flow technology to enhanced oil recovery. Recently, we have observed that for superspreading to occur, two key conditions must be simultaneously satisfied: the adsorption of surfactants from the liquid-vapor surface onto the three-phase contact line augmented by local bilayer formation. Crucially, this must be coordinated with the rapid replenishment of liquid-vapor and solid-liquid interfaces with surfactants from the interior of the droplet. Here, we present the structural characteristics and kinetics of the droplet spreading during the different stages of this process, and we compare our results with experimental data for trisiloxane and poly oxy ethylene surfactants. In this way, we highlight and explore the differences between surfactants, paving the way for the design of molecular architectures tailored specifically for applications that rely on the control of wetting. EPSRC Platform Grant MACIPh (EP/L020564/).

  2. An overview of STAR experimental results

    NASA Astrophysics Data System (ADS)

    Xu, Nu

    2014-11-01

    With large acceptance and excellent particle identification, STAR is one of the best mid-rapidity collider experiments for studying high-energy nuclear collisions. The STAR experiment provides full information on initial conditions, properties of the hot and dense medium as well as the properties at freeze-out. In Au+Au collisions at √{sNN} = 200 GeV, STAR's focus is on the nature of the sQGP produced at RHIC. In order to explore the properties of the QCD phase diagram, since 2010, the experiment has collected sizable data sets of Au+Au collisions at the lower collision energy region where the net-baryon density is large. At the 2014 Quark Matter Conference, the STAR experiment made 16 presentations that cover physics topics including collective dynamics, electromagnetic probes, heavy-flavor, initial state physics, jets, QCD phase diagram, thermodynamics and hadron chemistry, and future experimental facilities, upgrades, and instrumentation[1]. In this overview we will highlight a few results from the STAR experiment, especially those from the recent measurements of the RHIC beam energy scan program. At the end, instead of a summary, we will discuss STAR's near future physics programs at RHIC.

  3. The accurate measurement of second virial coefficients using self-interaction chromatography: experimental considerations.

    PubMed

    Quigley, A; Heng, J Y Y; Liddell, J M; Williams, D R

    2013-11-01

    Measurement of B22, the second virial coefficient, is an important technique for describing the solution behaviour of proteins, especially as it relates to precipitation, aggregation and crystallisation phenomena. This paper describes the best practise for calculating B22 values from self-interaction chromatograms (SIC) for aqueous protein solutions. Detailed analysis of SIC peak shapes for lysozyme shows that non-Gaussian peaks are commonly encountered for SIC, with typical peak asymmetries of 10%. This asymmetry reflects a non-linear chromatographic retention process, in this case heterogeneity of the protein-protein interactions. Therefore, it is important to use the centre of mass calculations for determining accurate retention volumes and thus B22 values. Empirical peak maximum chromatogram analysis, often reported in the literature, can result in errors of up to 50% in B22 values. A methodology is reported here for determining both the mean and the variance in B22 from SIC experiments, includes a correction for normal longitudinal peak broadening. The variance in B22 due to chemical effects is quantified statistically and is a measure of the heterogeneity of protein-protein interactions in solution. In the case of lysozyme, a wide range of B22 values are measured which can vary significantly from the average B22 values. PMID:23623796

  4. An experimental correction proposed for an accurate determination of mass diffusivity of wood in steady regime

    NASA Astrophysics Data System (ADS)

    Zohoun, Sylvain; Agoua, Eusèbe; Degan, Gérard; Perre, Patrick

    2002-08-01

    This paper presents an experimental study of the mass diffusion in the hygroscopic region of four temperate species and three tropical ones. In order to simplify the interpretation of the phenomena, a dimensionless parameter called reduced diffusivity is defined. This parameter varies from 0 to 1. The method used is firstly based on the determination of that parameter from results of the measurement of the mass flux which takes into account the conditions of operating standard device (tightness, dimensional variations and easy installation of samples of wood, good stability of temperature and humidity). Secondly the reasons why that parameter has to be corrected are presented. An abacus for this correction of mass diffusivity of wood in steady regime has been plotted. This work constitutes an advanced deal nowadays for characterising forest species.

  5. VALIDATION DATA FOR PHOTOCHEMICAL MECHANISMS: EXPERIMENTAL RESULTS

    EPA Science Inventory

    The smog chamber facility of the University of North Carolina (UNC) was used to provide experimental data for the EPA and atmospheric model developers for testing and validating kinetic mechanisms of photochemical smog formation. In the study, 71 dual-experiments were performed u...

  6. ANOVA parameters influence in LCF experimental data and simulation results

    NASA Astrophysics Data System (ADS)

    Delprete, C.; Sesanaa, R.; Vercelli, A.

    2010-06-01

    The virtual design of components undergoing thermo mechanical fatigue (TMF) and plastic strains is usually run in many phases. The numerical finite element method gives a useful instrument which becomes increasingly effective as the geometrical and numerical modelling gets more accurate. The constitutive model definition plays an important role in the effectiveness of the numerical simulation [1, 2] as, for example, shown in Figure 1. In this picture it is shown how a good cyclic plasticity constitutive model can simulate a cyclic load experiment. The component life estimation is the subsequent phase and it needs complex damage and life estimation models [3-5] which take into account of several parameters and phenomena contributing to damage and life duration. The calibration of these constitutive and damage models requires an accurate testing activity. In the present paper the main topic of the research activity is to investigate whether the parameters, which result to be influent in the experimental activity, influence the numerical simulations, thus defining the effectiveness of the models in taking into account of all the phenomena actually influencing the life of the component. To obtain this aim a procedure to tune the parameters needed to estimate the life of mechanical components undergoing TMF and plastic strains is presented for commercial steel. This procedure aims to be easy and to allow calibrating both material constitutive model (for the numerical structural simulation) and the damage and life model (for life assessment). The procedure has been applied to specimens. The experimental activity has been developed on three sets of tests run at several temperatures: static tests, high cycle fatigue (HCF) tests, low cycle fatigue (LCF) tests. The numerical structural FEM simulations have been run on a commercial non linear solver, ABAQUS®6.8. The simulations replied the experimental tests. The stress, strain, thermal results from the thermo structural FEM

  7. The use of experimental bending tests to more accurate numerical description of TBC damage process

    NASA Astrophysics Data System (ADS)

    Sadowski, T.; Golewski, P.

    2016-04-01

    Thermal barrier coatings (TBCs) have been extensively used in aircraft engines to protect critical engine parts such as blades and combustion chambers, which are exposed to high temperatures and corrosive environment. The blades of turbine engines are additionally exposed to high mechanical loads. These loads are created by the high rotational speed of the rotor (30 000 rot/min), causing the tensile and bending stresses. Therefore, experimental testing of coated samples is necessary in order to determine strength properties of TBCs. Beam samples with dimensions 50×10×2 mm were used in those studies. The TBC system consisted of 150 μm thick bond coat (NiCoCrAlY) and 300 μm thick top coat (YSZ) made by APS (air plasma spray) process. Samples were tested by three-point bending test with various loads. After bending tests, the samples were subjected to microscopic observation to determine the quantity of cracks and their depth. The above mentioned results were used to build numerical model and calibrate material data in Abaqus program. Brittle cracking damage model was applied for the TBC layer, which allows to remove elements after reaching criterion. Surface based cohesive behavior was used to model the delamination which may occur at the boundary between bond coat and top coat.

  8. Experimental results of the betatron sum resonance

    SciTech Connect

    Wang, Y.; Ball, M.; Brabson, B.

    1993-06-01

    The experimental observations of motion near the betatron sum resonance, {nu}{sub x} + 2{nu}{sub z} = 13, are presented. A fast quadrupole (Panofsky-style ferrite picture-frame magnet with a pulsed power supplier) producing a betatron tune shift of the order of 0.03 at rise time of 1 {mu}s was used. This quadrupole was used to produce betatron tunes which jumped past and then crossed back through a betatron sum resonance line. The beam response as function of initial betatron amplitudes were recorded turn by turn. The correlated growth of the action variables, J{sub x} and J{sub z}, was observed. The phase space plots in the resonance frame reveal the features of particle motion near the nonlinear sum resonance region.

  9. Experimental study of radiometric forces with comparison to computational results

    NASA Astrophysics Data System (ADS)

    Selden, Nathaniel P.

    A study of the radiometric forces on heated plates has been conducted both experimentally and computationally. The experiments were carried out at USC in two vacuum chambers up to a maximum pressure of 6 Pa for various carrier gases. The computations were performed with both the DSMC and ES-BGK methods for a 2-D gas flow over a comparable range of pressures. It is shown that the radiometric devices provide maximum force at a Knudsen number approximating 0.1. Of the various gases tested, helium provides the largest peak force. Qualitatively, the experimental data and computational results are similar. A lack of experimental data on gas-surface accommodation and flow three-dimensionality yields up to a 40% difference in the magnitude of the measured and computed forces, but it is shown that this discrepancy can be used to predict accommodation values. Comparison of four geometric configurations has shown that the effect of the area is significant at pressures up to where the force is maximum. It is also demonstrated that the size of the chamber in which the radiometer resides is of primary importance, where the chamber dimensions are inversely related to the generated force. Finally, simulation of multi-vane configurations have shown that the optimal spacing of vanes can be tailored for specific uses; for maximum force production a tight spacing should be used, while maximum efficiency requires spacing on the order of a vane dimension. While the results so far are encouraging, they are far from complete. Further improvements would include: a new experimental setup to reduce uncertainty with highly accurate temperature control and measurement, an in situ way to prepare the surface as well as measure its cleanliness, and an in depth iterative computational study observing the impact of multiple radiometer vanes at numerous seperations.

  10. Theory of bi-molecular association dynamics in 2D for accurate model and experimental parameterization of binding rates

    NASA Astrophysics Data System (ADS)

    Yogurtcu, Osman N.; Johnson, Margaret E.

    2015-08-01

    The dynamics of association between diffusing and reacting molecular species are routinely quantified using simple rate-equation kinetics that assume both well-mixed concentrations of species and a single rate constant for parameterizing the binding rate. In two-dimensions (2D), however, even when systems are well-mixed, the assumption of a single characteristic rate constant for describing association is not generally accurate, due to the properties of diffusional searching in dimensions d ≤ 2. Establishing rigorous bounds for discriminating between 2D reactive systems that will be accurately described by rate equations with a single rate constant, and those that will not, is critical for both modeling and experimentally parameterizing binding reactions restricted to surfaces such as cellular membranes. We show here that in regimes of intrinsic reaction rate (ka) and diffusion (D) parameters ka/D > 0.05, a single rate constant cannot be fit to the dynamics of concentrations of associating species independently of the initial conditions. Instead, a more sophisticated multi-parametric description than rate-equations is necessary to robustly characterize bimolecular reactions from experiment. Our quantitative bounds derive from our new analysis of 2D rate-behavior predicted from Smoluchowski theory. Using a recently developed single particle reaction-diffusion algorithm we extend here to 2D, we are able to test and validate the predictions of Smoluchowski theory and several other theories of reversible reaction dynamics in 2D for the first time. Finally, our results also mean that simulations of reactive systems in 2D using rate equations must be undertaken with caution when reactions have ka/D > 0.05, regardless of the simulation volume. We introduce here a simple formula for an adaptive concentration dependent rate constant for these chemical kinetics simulations which improves on existing formulas to better capture non-equilibrium reaction dynamics from dilute

  11. Development and experimental verification of a finite element method for accurate analysis of a surface acoustic wave device

    NASA Astrophysics Data System (ADS)

    Mohibul Kabir, K. M.; Matthews, Glenn I.; Sabri, Ylias M.; Russo, Salvy P.; Ippolito, Samuel J.; Bhargava, Suresh K.

    2016-03-01

    Accurate analysis of surface acoustic wave (SAW) devices is highly important due to their use in ever-growing applications in electronics, telecommunication and chemical sensing. In this study, a novel approach for analyzing the SAW devices was developed based on a series of two-dimensional finite element method (FEM) simulations, which has been experimentally verified. It was found that the frequency response of the two SAW device structures, each having slightly different bandwidth and center lobe characteristics, can be successfully obtained utilizing the current density of the electrodes via FEM simulations. The two SAW structures were based on XY Lithium Niobate (LiNbO3) substrates and had two and four electrode finger pairs in both of their interdigital transducers, respectively. Later, SAW devices were fabricated in accordance with the simulated models and their measured frequency responses were found to correlate well with the obtained simulations results. The results indicated that better match between calculated and measured frequency response can be obtained when one of the input electrode finger pairs was set at zero volts and all the current density components were taken into account when calculating the frequency response of the simulated SAW device structures.

  12. Accurate experimental and theoretical comparisons between superconductor-insulator-superconductor mixers showing weak and strong quantum effects

    NASA Technical Reports Server (NTRS)

    Mcgrath, W. R.; Richards, P. L.; Face, D. W.; Prober, D. E.; Lloyd, F. L.

    1988-01-01

    A systematic study of the gain and noise in superconductor-insulator-superconductor mixers employing Ta based, Nb based, and Pb-alloy based tunnel junctions was made. These junctions displayed both weak and strong quantum effects at a signal frequency of 33 GHz. The effects of energy gap sharpness and subgap current were investigated and are quantitatively related to mixer performance. Detailed comparisons are made of the mixing results with the predictions of a three-port model approximation to the Tucker theory. Mixer performance was measured with a novel test apparatus which is accurate enough to allow for the first quantitative tests of theoretical noise predictions. It is found that the three-port model of the Tucker theory underestimates the mixer noise temperature by a factor of about 2 for all of the mixers. In addition, predicted values of available mixer gain are in reasonable agreement with experiment when quantum effects are weak. However, as quantum effects become strong, the predicted available gain diverges to infinity, which is in sharp contrast to the experimental results. Predictions of coupled gain do not always show such divergences.

  13. Experimental rotordynamic coefficient results for honeycomb seals

    NASA Technical Reports Server (NTRS)

    Elrod, David A.; Childs, Dara W.

    1988-01-01

    Test results (leakage and rotordynamic coefficients) are presented for seven honeycomb-stator smooth-rotor seals. Tests were carried out with air at rotor speeds up to 16,000 cpm and supply pressures up to 8.2 bars. Test results for the seven seals are compared, and the most stable configuration is identified based on the whirl frequency ratio. Results from tests of a smooth-rotor/smooth-stator seal, a teeth-on-stator labyrinth seal, and the most stable honeycomb seal are compared.

  14. Adaptive structures - Test hardware and experimental results

    NASA Technical Reports Server (NTRS)

    Wada, Ben K.; Fanson, James L.; Chen, Gun-Shing; Kuo, Chin-Po

    1990-01-01

    The facilities and procedures used at JPL to test adaptive structures such as the large deployable reflector (LDR) are described and preliminary results are reported. The applications of adaptive structures in future NASA missions are outlined, and the techniques which are employed to modify damping, stiffness, and isolation characteristics, as well as geometric changes, are listed. The development of adaptive structures is shown to be effective as a result of new actuators and sensors, and examples are listed for categories such as fiber optics, shape-memory materials, piezoelectrics, and electrorheological fluids. Some ground test results are described for laboratory truss structures and truss test beds, which are shown to be efficient and easy to assemble in space. Adaptive structures are shown to be important for precision space structures such as the LDR, and can alleviate ground test requirements.

  15. The Humanoid Robot LOLA—Experimental Results

    NASA Astrophysics Data System (ADS)

    Favot, V.; Schwienbacher, M.; Buschmann, T.; Lohmeier, S.; Ulbrich, H.

    2010-09-01

    With the experience gathered during the development and construnction of the robot JOHNNIE, a new humanoid robot LOLA was built. Goal of this project is to realize a fast, human-like walking. Different aspects of this complex mechatronic system and the first experiments results are presented. The lightweight construction and the custom build multi-sensory joint drives with high torque brushless motors are introduced. The new decentralized electronic control/sensing network is also discuss as well as the simulation environment, the trajectory planning algorithm and the stabilizing walking control. Finally the first experiments result are presented.

  16. Numerical taxonomy on data: Experimental results

    SciTech Connect

    Cohen, J.; Farach, M.

    1997-12-01

    The numerical taxonomy problems associated with most of the optimization criteria described above are NP - hard [3, 5, 1, 4]. In, the first positive result for numerical taxonomy was presented. They showed that if e is the distance to the closest tree metric under the L{sub {infinity}} norm. i.e., e = min{sub T} [L{sub {infinity}} (T-D)], then it is possible to construct a tree T such that L{sub {infinity}} (T-D) {le} 3e, that is, they gave a 3-approximation algorithm for this problem. We will refer to this algorithm as the Single Pivot (SP) heuristic.

  17. Experimental results on constructed wetland pilot system.

    PubMed

    González, J M; Ansola, G; Luis, E

    2001-01-01

    Research into a constructed wetland for wastewater treatment using M.H.E.A. (Hierarchical Mosaic of Artificial Ecosystems) pilot system was carried out over a vegetative period in 8 different flow and vegetable composition series. The system consisted of a free water pond as a first step working as primary treatment followed by a zone with Typha sp. and surface flow and finally a woody zone with a subsurface flow and planted with ligneous species (Salixsp., Populus sp., Fraxinus sp. and Alnus sp.). Removal efficiency in the study reflects an optimal result: 80-99% total suspended matter removal, 82-98% organic matter removal, 70-98% nutrients removal and up to 99.9% faecal bacterial disinfecting. Effluent characteristics were in accordance with European Union legislation criteria for wastewater treatment systems. PMID:11804123

  18. Nulling interferometry: symmetry requirements and experimental results

    NASA Astrophysics Data System (ADS)

    Serabyn, Eugene

    2000-07-01

    This paper provides a derivation from first principles of the stringent symmetry and stability requirements which deep stellar nulling demands, and also includes a brief status report on recent nulling results obtained with the Jet Propulsion Laboratory's fiber-coupled rotational-shearing interferometer. To date, the deepest transient nulls obtained (at red wavelengths) are 2 X 10-6 with a laser diode source, and 1.4 X 10-5 with a single- polarization thermal white-light source filtered to provide an 18% passband. In addition, both the laser and white light nulls have been stabilized to the 10-4 level. This visible wavelength laboratory nuller thus meets essentially all of the performance goals for the planned nulling experiment on board NASA's Space Interferometer Mission, with the sole exception of dual-polarization operation.

  19. Reactor-pumped laser experimental results

    SciTech Connect

    Hebner, G.A.; Hays, G.N.

    1994-12-31

    Reactor pumped lasers have the potential to be scaled to multi-megawatt power levels with long run times. In proposed designs, the laser will be capable of output powers of several megawatts of power for run times of several hours. Such a laser would have many diverse applications such as material processing, space debris removal and power beaming to geosynchronous satellites or the moon. However, before such systems can be designed, fundamental laser parameters such as small signal gain, saturation intensity and efficiency must be determined over a wide operational parameter space. The authors have recently measured fundamental laser parameters for a selection of nuclear pumped visible and near IR laser transitions in atomic neon, argon and xenon. An overview of the results of this investigation will be presented.

  20. Experimental results from the TFTR tokamak

    SciTech Connect

    Hawryluk, R.J.; Arunasalam, V.; Bell, J.D.; Bell, M.G.; Bitter, M.; Blanchard, W.R.; Bloody, F.; Bretz, N.; Budny, R.; Bush, C.E.

    1986-10-01

    Recent experiments on TFTR have extended the operating regime of TFTR in both ohmic- and neutral-beam-heated discharges. The TFTR tokamak has reached its original machine design specifications (I/sub p/ = 2.5 MA and B/sub T/ = 5.2 T). Initial neutral-beam-heating experiments used up to 6.3 MW of deuterium beams. With the recent installation of two additional beamlines, the power has been increased up to 11 MW. A deuterium pellet injector was used to increase the central density to 2.5 x 10/sup 20/ m/sup -3/ in high current discharges. At the opposite extreme, by operating at low plasma current (I/sub p/ approx. 0.8 MA) and low density (anti n/sub e/ approx. 1 x 10/sup 19/ m/sup -3/), high ion temperatures (9 +- 2 keV) and rotation speeds (7 x 10/sup 5/ m/s) have been achieved during injection. In addition, plasma compression experiments have demonstrated acceleration of beam ions from 82 keV to 150 keV, in accord with expectations. The wide operating range of TFTR, together with an extensive set of diagnostics and a flexible control system, has facilitated transport and scaling studies of both ohmic- and neutral-beam-heated discharges. The results of these confinement studies are presented.

  1. Overview of the initial NSTX experimental results

    NASA Astrophysics Data System (ADS)

    Ono, M.; Bell, M. G.; Bell, R. E.; Bigelow, T.; Bitter, M.; Blanchard, W.; Darrow, D. S.; Fredrickson, E. D.; Gates, D. A.; Grisham, L. R.; Hosea, J. C.; Johnson, D. W.; Kaita, R.; Kaye, S. M.; Kubota, S.; Kugel, H. W.; LeBlanc, B. P.; Maingi, R.; Maqueda, R.; Mazzucato, E.; Menard, J.; Mueller, D.; Nelson, B. A.; Neumeyer, C.; Paoletti, F.; Paul, S. F.; Peng, Y.-K. M.; Ramakrishnan, S.; Raman, R.; Ryan, P. M.; Sabbagh, S. A.; Skinner, C. H.; Stevenson, T.; Stutman, D.; Swain, D. W.; Synakowski, E. J.; Taylor, G.; Von Halle, A.; Wilgen, J.; Williams, M.; Wilson, J. R.; Zweben, S. J.; Ackers, R.; Barry, R. E.; Bers, A.; Bialek, J. M.; Bonoli, P. T.; Carter, M. D.; Chrzanowski, J.; Davis, W.; Doyle, E. J.; Dudek, L.; Efthimion, P. C.; Ellis, R.; Ferron, J. R.; Finkenthal, M.; Fredd, E.; Gibney, T.; Goldston, R. J.; Hatcher, R. E.; Hawryluck, R. J.; Hayashiya, H.; Hill, K. W.; Jarboe, T. R.; Jardin, S. C.; Ji, H.; Kalish, M.; La Marche, P.; Lao, L. L.; Lee, K. C.; Levinton, F. M.; Luhmann, N. C.; Majeski, R.; Manickam, J.; Marsala, R.; Mau, T. K.; McCormack, B.; Medley, S. S.; Menon, M. M.; Mitarai, O.; Nagata, M.; Nishino, N.; Oliaro, G.; Park, H. K.; Parsells, R.; Pearson, G.; Peebles, T.; Phillips, C. K.; Pinsker, R.; Porter, G. D.; Ram, A. K.; Robinson, J.; Roney, P.; Roquemore, A. L.; Rosenberg, A.; Schaffer, M.; Shiraiwa, S.; Sichta, P.; Stotler, D.; Stratton, B. C.; Takase, Y.; Wampler, W. R.; Wurden, G. A.; Xu, X. Q.; Yang, J. G.; Zeng, L.; Zhu, W.

    2001-10-01

    The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 MA on 14 December 1999. The planned plasma shaping parameters, elongation κ = 1.6-2.2 and triangularity δ = 0.2-0.4, were achieved in inner wall limited, and single null and double null diverted configurations. The coaxial helicity injection (CHI) and high harmonic fast wave (HHFW) experiments were also initiated. CHI current of 27 kA produced up to 260 kA toroidal current without using an ohmic solenoid. With the injection of 2.3 MW of HHFW power, using 12 antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a central density of 3.5 × 1013 cm-3, increasing the plasma energy to 59 kJ and the toroidal β, βT, to 10%. The NBI system commenced operation in September 2000. The initial results with two ion sources (PNBI = 2.8 MW) show good heating, producing a total plasma stored energy of 90 kJ corresponding to βT approx 18% at a plasma current of 1.1 MA.

  2. Liquid hydrogen for automotive vehicles - Experimental results

    SciTech Connect

    Peschka, W.

    1981-01-01

    A BMW-518 has been adapted for LH2-fuel, representing the first LH2-fueled car in Europe. This is a joint program between the German Research and Testing Laboratory for Aeronautics and the Research Institute for Motor-Transport Service and Automotive Engines at the University of Stuttgart. The program was established for demonstration of successful car-operation and and the safe handling of LH2-fuel during car operation and refueling. Based on earlier papers, more recent test results and experiences are reported about car operation and engine performance. The car has been driven over an accumulated distance of about 1800 km on a test track. The test track consists of a loop of about 2.5 km in length, including a proper combination of straight level sections, curved sections and ascending sections. In order to demonstrate a safe liquid hydrogen refueling procedure that could also be used by untrained people, a semiautomatic computer operated refueling station has been developed. This refueling station is in successful operation.

  3. Overview of the Initial NSTX Experimental Results

    SciTech Connect

    M. Ono; M. Bell; R. E. Bell; T. Bigelow; M. Bitter; et al

    2000-11-16

    The main aim of the National Spherical Torus Experiment (NSTX) is to establish the fusion physics principles of the spherical torus (ST) concept. The NSTX device began plasma operations in February 1999 and the plasma current Ip was successfully brought up to the design value of 1 million amperes on December 14, 1999. The planned plasma shaping parameters, k = 1.6 {+-} 2.2 and d = 0.2 {+-} 0.4, were achieved in inner limited, single null and double null configurations. The CHI (Coaxial Helicity Injection) and HHFW (High Harmonic Fast Wave) experiments were also initiated. A CHI injected current of 27 kA produced up to 260 kA of toroidal current without using an ohmic solenoid. With an injection of 2.3 MW of HHFW power, using twelve antennas connected to six transmitters, electrons were heated from a central temperature of 400 eV to 900 eV at a centraldensity of 3.5 x 1013 cm-3 increasing the plasma energy to 59 kJ and the toroidal beta, bT to 10 %. Finally, the NBI system commenced operatio n in Sept. 2000. The initial results with two ion sources (PNBI = 2.8 MW) shows good heating, producing a total plasma stored energy of 90 kJ corresponding to bT = 18 % at a plasma current of 1.1 MA

  4. Experimental results of guided wave travel time tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Vos, Hendrik

    2012-05-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation matches very well with the objective to reduce cost while maintaining a high safety level. Guided waves are very attractive for permanent monitoring systems because it provides a wall thickness map in between two sensor rings. The wall thickness map provides quantitative information about the remaining wall thickness, location and extent of the corrosion. The performance of guided wave tomography has been evaluated experimentally assessing the sizing accuracy and the smallest corrosion spots that can be detected with this technology. The results show accurate sizing, with a sizing accuracy better than 10% of the nominal wall thickness. Additionally, the maximum distance between the transmitter and receiver rings and the presence of different coatings has been evaluated. The results demonstrate the robustness of the technology under a range of practical conditions.

  5. An experimental device for accurate ultrasounds measurements in liquid foods at high pressure

    NASA Astrophysics Data System (ADS)

    Hidalgo-Baltasar, E.; Taravillo, M.; Baonza, V. G.; Sanz, P. D.; Guignon, B.

    2012-12-01

    The use of high hydrostatic pressure to ensure safe and high-quality product has markedly increased in the food industry during the last decade. Ultrasonic sensors can be employed to control such processes in an equivalent way as they are currently used in processes carried out at room pressure. However, their installation, calibration and use are particularly challenging in the context of a high pressure environment. Besides, data about acoustic properties of food under pressure and even for water are quite scarce in the pressure range of interest for food treatment (namely, above 200 MPa). The objective of this work was to establish a methodology to determine the speed of sound in foods under pressure. An ultrasonic sensor using the multiple reflections method was adapted to a lab-scale HHP equipment to determine the speed of sound in water between 253.15 and 348.15 K, and at pressures up to 700 MPa. The experimental speed-of-sound data were compared to the data calculated from the equation of state of water (IAPWS-95 formulation). From this analysis, the way to calibrate cell path was validated. After this calibration procedure, the speed of sound could be determined in liquid foods by using this sensor with a relative uncertainty between (0.22 and 0.32) % at a confidence level of 95 % over the whole pressure domain.

  6. Convenient, Rapid and Accurate Measurement of SVOC Emission Characteristics in Experimental Chambers

    PubMed Central

    Liu, Cong; Liu, Zhe; Little, John C.; Zhang, Yinping

    2013-01-01

    Chamber tests are usually used to determine the source characteristics of semi-volatile organic compounds (SVOCs) which are critical to quantify indoor exposure to SVOCs. In contrast to volatile organic compounds (VOCs), the sorption effect of SVOCs to chamber surfaces usually needs to be considered due to the much higher surface/air partition coefficients, resulting in a long time to reach steady state, frequently on the order of months, and complicating the mathematical analysis of the resulting data. A chamber test is also complicated if the material-phase concentration is not constant. This study shows how to design a chamber to overcome these limitations. A dimensionless mass transfer analysis is used to specify conditions for (1) neglecting the SVOC sorption effect to chamber surfaces, (2) neglecting the convective mass transfer resistance at sorption surfaces if the sorption effect cannot be neglected, and (3) regarding the material-phase concentration in the source as constant. Several practical and quantifiable ways to improve chamber design are proposed. The approach is illustrated by analyzing available data from three different chambers in terms of the accuracy with which the model parameters can be determined and the time needed to conduct the chamber test. The results should greatly facilitate the design of chambers to characterize SVOC emissions and the resulting exposure. PMID:24015246

  7. Results from an experimental railgun system: ERGS-1A

    NASA Astrophysics Data System (ADS)

    Thio, Y. C.; Clark, G. A.; Bedford, A. J.

    1983-03-01

    One phase of the Materials Research Laboratories (MRL) Experimental Rail-gun System (ERGS-1) program is for experimentation in the energy range 50 to 500 kJ. The first, and highly successful, ERGS-1 experiment was conducted in September 1981 using a barrel segment 200 mm in length. Comparison of experimental results with the theory developed by Thio yielded good agreement, particularly the values for capacitor voltage, current through the rails, plasma voltage and muzzle velocity of the projectile.

  8. Geoacoustic and source tracking using particle filtering: experimental results.

    PubMed

    Yardim, Caglar; Gerstoft, Peter; Hodgkiss, William S

    2010-07-01

    A particle filtering (PF) approach is presented for performing sequential geoacoustic inversion of a complex ocean acoustic environment using a moving acoustic source. This approach treats both the environmental parameters [e.g., water column sound speed profile (SSP), water depth, sediment and bottom parameters] at the source location and the source parameters (e.g., source depth, range and speed) as unknown random variables that evolve as the source moves. This allows real-time updating of the environment and accurate tracking of the moving source. As a sequential Monte Carlo technique that operates on nonlinear systems with non-Gaussian probability densities, the PF is an ideal algorithm to perform tracking of environmental and source parameters, and their uncertainties via the evolving posterior probability densities. The approach is demonstrated on both simulated data in a shallow water environment with a sloping bottom and experimental data collected during the SWellEx-96 experiment. PMID:20649203

  9. Experimental study of the Timoshenko beam theory predictions: Further results

    NASA Astrophysics Data System (ADS)

    Monsivais, G.; Díaz-de-Anda, A.; Flores, J.; Gutiérrez, L.; Morales, A.

    2016-08-01

    In a previous paper (2012) we presented experimental results proving that the critical frequency fC predicted by Timoshenko beam theory indeed exists. We also showed that for frequencies f smaller than fC the spectrum is formed by almost equally spaced levels whereas for f >fC the spectrum consists of pairs of eigenvalues very close to each other as predicted by numerical solutions of Timoshenko's equation: we shall refer to them as Timoshenko doublets. In this work we measure for the first time experimental dispersion relations. For this purpose it was necessary to obtain normal-mode amplitudes with a high precision, which was done with a new experimental setup developed by us. We found that experimental dispersion relations coincide very well with theoretical predictions. Furthermore, we provide an explanation of Timoshenko doublets.

  10. Ultrasonic radiation from wedges of cubic profile: Experimental results.

    PubMed

    Anderson, Brian E; Remillieux, Marcel C; Le Bas, Pierre-Yves; Ulrich, T J; Pieczonka, Lukasz

    2015-12-01

    This paper presents experimental results demonstrating the increase in ultrasonic radiation obtained from a wedge of cubic profile relative to a plate of uniform thickness. The wedge of cubic profile provides high efficiency sound radiation matching layer from a mounted piezoelectric transducer into the surrounding air. Previous research on structures with indentations of power-law profile has focused on vibration mitigation using the so called "acoustic black-hole" effect, whereas here such structures are used to enhance ultrasonic radiation. The work provides experimental verification of the numerical results of Remillieux et al. (2014). PMID:26166628

  11. Comparison of calculated and experimental results of fragmenting cylinder experiments

    SciTech Connect

    WILSON,L.T.; REEDAL,D.R.; KIPP,MARLIN E.; MARTINEZ,REINA R.; GRADY,D.E.

    2000-06-02

    The Grady-Kipp fragmentation model provides a physically based method for determining the fracture and breakup of materials under high loading rates. Recently, this model has been implemented into the CTH Shock Physics Code and has been used to simulate several published experiments. Materials studied in this paper are AerMet 100 steel and a 90% tungsten alloy. The experimental geometry consists of a right circular cylinder filled with an explosive main charge that is initiated at its center. The sudden expansion of the resulting detonation products causes fracture of the cylinder. Strain rates seen in the cylinder are on the order of 10{sup 4} s{sup {minus}1}. The average fragment sizes calculated with the Grady-Kipp fragmentation model successfully replicate the mean fragment size obtained from the experimental fragment distribution. When Poisson statistics are applied to the calculated local average fragment sizes, good correlation is also observed with the shape of the experimental cumulative fragment distribution. The experimental fragmentation results, CTH numerical simulations, and correlation of these numerical results with the experimental data are described.

  12. CSI sensing and control: Analytical and experimental results

    NASA Technical Reports Server (NTRS)

    Junkins, J. L.; Pollock, T. C.; Rahman, Z. H.

    1989-01-01

    Recent work on structural identification and large-angle maneuvers with vibration suppression was presented. The recent work has sought to balance structural and controls analysis activities by involving the analysts directly in the validation and experimental aspects of the research. Some new sensing, actuation, system identification, and control concepts were successfully implemented. An overview of these results is given.

  13. Design and experimental results for the S805 airfoil

    SciTech Connect

    Somers, D.M.

    1997-01-01

    An airfoil for horizontal-axis wind-turbine applications, the S805, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  14. Design and experimental results for the S809 airfoil

    SciTech Connect

    Somers, D M

    1997-01-01

    A 21-percent-thick, laminar-flow airfoil, the S809, for horizontal-axis wind-turbine applications, has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of restrained maximum lift, insensitive to roughness, and low profile drag have been achieved. The airfoil also exhibits a docile stall. Comparisons of the theoretical and experimental results show good agreement. Comparisons with other airfoils illustrate the restrained maximum lift coefficient as well as the lower profile-drag coefficients, thus confirming the achievement of the primary objectives.

  15. Experimental results of a predictive neural network HVAC controller

    SciTech Connect

    Jeannette, E.; Assawamartbunlue, K.; Kreider, J.F.; Curtiss, P.S.

    1998-12-31

    Proportional, integral, and derivative (PID) control is widely used in many HVAC control processes and requires constant attention for optimal control. Artificial neural networks offer the potential for improved control of processes through predictive techniques. This paper introduces and shows experimental results of a predictive neural network (PNN) controller applied to an unstable hot water system in an air-handling unit. Actual laboratory testing of the PNN and PID controllers show favorable results for the PNN controller.

  16. Robustness to noise in synchronization of network motifs: Experimental results

    NASA Astrophysics Data System (ADS)

    Buscarino, Arturo; Fortuna, Luigi; Frasca, Mattia; Iachello, Marco; Pham, Viet-Thanh

    2012-12-01

    In this work, we experimentally investigate the robustness to noise of synchronization in all the four-nodes network motifs. The experimental setup consists of four Chua's circuits diffusively coupled in order to implement the six different undirected network motifs that can be obtained with four nodes. In this experimental setup, synchronization in the presence of noise injected in one of the network nodes is investigated and network motifs are compared in terms of the synchronization error obtained. The analysis has been then extended to some selected case studies of networks with five and six nodes. Numerical simulations have been also performed and results in agreement with experiments have been obtained. A correlation between node degree and robustness to noise has been found also in these networks.

  17. Experimental results for a hypersonic nozzle/afterbody flow field

    NASA Technical Reports Server (NTRS)

    Spaid, Frank W.; Keener, Earl R.; Hui, Frank C. L.

    1995-01-01

    This study was conducted to experimentally characterize the flow field created by the interaction of a single-expansion ramp-nozzle (SERN) flow with a hypersonic external stream. Data were obtained from a generic nozzle/afterbody model in the 3.5 Foot Hypersonic Wind Tunnel at the NASA Ames Research Center, in a cooperative experimental program involving Ames and McDonnell Douglas Aerospace. The model design and test planning were performed in close cooperation with members of the Ames computational fluid dynamics (CFD) team for the National Aerospace Plane (NASP) program. This paper presents experimental results consisting of oil-flow and shadow graph flow-visualization photographs, afterbody surface-pressure distributions, rake boundary-layer measurements, Preston-tube skin-friction measurements, and flow field surveys with five-hole and thermocouple probes. The probe data consist of impact pressure, flow direction, and total temperature profiles in the interaction flow field.

  18. Novel Thermoelectric Modules for Cooling Powerful LEDs: Experimental Results

    NASA Astrophysics Data System (ADS)

    Semenyuk, V.; Dekhtiaruk, R.

    2013-07-01

    We present the results of an experimental study of a cooling system based on a novel thermoelectric module specifically designed for thermal management of high-power light-emitting diodes (LEDs). The Seoul Semiconductor LED W724C0 device was chosen for experimental validation of the efficiency of the proposed cooling unit. Two cooling systems with identical heat sinks were tested for comparison: a state-of-the-art one based on an insulated metal substrate-printed circuit board (IMS-PCB), and a system with thermoelectric cooling. The obtained results show that use of thermoelectrics results in a considerable reduction of the LED operating temperature, providing increased light output and greatly increased LED lifetime.

  19. Feedback control of a cupola - concepts and experimental results

    SciTech Connect

    Moore, K.L.; Abdelrahman, M.A.; Larsen, E.; Clark, D.; King, P.

    1998-10-01

    In this paper we present some final results from a research project focused on introducing automatic control to the operation of cupola iron furnaces. The main aim of this research is to improve the operational efficiency and performance of the cupola furnace, an important foundry process used to melt iron. Previous papers have described the development of appropriate control system architectures for the cupola. These results are summarized. Then we describe the experimental results obtained with the U.S. Department of Energy Albany Research Center`s research cupola. First, experimental data is used to calibrate the model, which is taken as a first-order multivariable system with time delay. Then relative gain analysis is used to select loop pairings to be used in a multi-loop controller. The resulting controller pairs meltrate with blast volume, iron temperature with oxygen addition, and carbon composition with percent coke. Special (nonlinear) filters are used to compute meltrate from actual scale readings of the amount of iron produced and to smooth the temperature measurement. The temperature and meltrate loops use single-loop PI control. The composition loop uses a Smith predictor to discount the deadtime associated with mass transport through the furnace. Experimental results validate the conceptual controller design and provide proof-of-concept of the idea of controlling a foundry cupola. Future research directions are discussed, including the concept of an integrated, intelligent industrial process controller, or I{sup 3}PC.

  20. Experimental overview of COMPASS and CLAS results on TMDs

    NASA Astrophysics Data System (ADS)

    Riedl, Caroline

    2016-03-01

    In the past years, distribution functions depending on the transverse momentum of partons in the nucleon (TMDs) have been intensely studied in spin physics. The TMDs represent one approach to disentangle the multi-dimensional structure of the nucleon. Correlations of the transverse spin of quarks with their transverse momentum can be observed by measuring spin azimuthal asymmetries. Experimental results from the COMPASS (CERN) and CLAS (Jefferson Laboratory) collaborations are presented and an outlook to upcoming measurements at these facilities is given.

  1. Modeling and experimental result analysis for high-power VECSELs

    NASA Astrophysics Data System (ADS)

    Zakharian, Aramais R.; Hader, Joerg; Moloney, Jerome V.; Koch, Stephan W.; Lutgen, Stephan; Brick, Peter; Albrecht, Tony; Grotsch, Stefan; Luft, Johann; Spath, Werner

    2003-06-01

    We present a comparison of experimental and microscopically based model results for optically pumped vertical external cavity surface emitting semiconductor lasers. The quantum well gain model is based on a quantitative ab-initio approach that allows calculation of a complex material susceptibility dependence on the wavelength, carrier density and lattice temperature. The gain model is coupled to the macroscopic thermal transport, spatially resolved in both the radial and longitudinal directions, with temperature and carrier density dependent pump absorption. The radial distribution of the refractive index and gain due to temperature variation are computed. Thermal managment issues, highlighted by the experimental data, are discussed. Experimental results indicate a critical dependence of the input power, at which thermal roll-over occurs, on the thermal resistance of the device. This requires minimization of the substrate thickness and optimization of the design and placement of the heatsink. Dependence of the model results on the radiative and non-radiative carrier recombination lifetimes and cavity losses are evaluated.

  2. Mechanical properties of triaxially braided composites: Experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Masters, John E.; Foye, Raymond L.; Pastore, Christopher M.; Gowayed, Yasser A.

    1992-01-01

    The unnotched tensile properties of 2-D triaxial braid reinforced composites from both an experimental and an analytical viewpoint are studied. The materials are graphite fibers in an epoxy matrix. Three different reinforcing fiber architectures were considered. Specimens were cut from resin transfer molded (RTM) composite panels made from each braid. There were considerable differences in the observed elastic constants from different size strain gage and extensometer reading. Larger strain gages gave more consistent results and correlated better with the extensometer reading. Experimental strains correlated reasonably well with analytical predictions in the longitudinal, 0 degrees, fiber direction but not in the transverse direction. Tensile strength results were not always predictable even in reinforcing directions. Minor changes in braid geometry led to disproportionate strength variations. The unit cell structure of the triaxial braid was discussed with the assistance of computer analysis of the microgeometry. Photomicrographs of braid geometry were used to improve upon the computer graphics representations of unit cells. These unit cells were used to predict the elastic moduli with various degrees of sophistication. The simple and the complex analyses were generally in agreement but none adequately matched the experimental results for all the braids.

  3. Mechanical properties of triaxially braided composites: Experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Masters, John E.; Foye, Raymond L.; Pastore, Christopher M.; Gowayed, Yasser A.

    1992-01-01

    This paper investigates the unnotched tensile properties of two-dimensional triaxial braid reinforced composites from both an experimental and analytical viewpoint. The materials are graphite fibers in an epoxy matrix. Three different reinforcing fiber architectures were considered. Specimens were cut from resin transfer molded (RTM) composite panels made from each braid. There were considerable differences in the observed elastic constants from different size strain gage and extensometer readings. Larger strain gages gave more consistent results and correlated better with the extensometer readings. Experimental strains correlated reasonably well with analytical predictions in the longitudinal, zero degree, fiber direction but not in the transverse direction. Tensile strength results were not always predictable even in reinforcing directions. Minor changes in braid geometry led to disproportionate strength variations. The unit cell structure of the triaxial braid was discussed with the assistence of computer analysis of the microgeometry. Photomicrographs of the braid geometry were used to improve upon the computer graphics representations of unit cells. These unit cells were used to predict the elastic moduli with various degrees of sophistication. The simple and the complex analyses were generally in agreement but none adequately matched the experimental results for all the braids.

  4. Visual Mapping of Sedimentary Facies Can Yield Accurate And Geomorphically Meaningful Results at Morphological Unit to River Segment Scales

    NASA Astrophysics Data System (ADS)

    Pasternack, G. B.; Wyrick, J. R.; Jackson, J. R.

    2014-12-01

    Long practiced in fisheries, visual substrate mapping of coarse-bedded rivers is eschewed by geomorphologists for inaccuracy and limited sizing data. Geomorphologists perform time-consuming measurements of surficial grains, with the few locations precluding spatially explicit mapping and analysis of sediment facies. Remote sensing works for bare land, but not vegetated or subaqueous sediments. As visual systems apply the log2 Wentworth scale made for sieving, they suffer from human inability to readily discern those classes. We hypothesized that size classes centered on the PDF of the anticipated sediment size distribution would enable field crews to accurately (i) identify presence/absence of each class in a facies patch and (ii) estimate the relative amount of each class to within 10%. We first tested 6 people using 14 measured samples with different mixtures. Next, we carried out facies mapping for ~ 37 km of the lower Yuba River in California. Finally, we tested the resulting data to see if it produced statistically significant hydraulic-sedimentary-geomorphic results. Presence/absence performance error was 0-4% for four people, 13% for one person, and 33% for one person. The last person was excluded from further effort. For the abundance estimation performance error was 1% for one person, 7-12% for three people, and 33% for one person. This last person was further trained and re-tested. We found that the samples easiest to visually quantify were unimodal and bimodal, while those most difficult had nearly equal amounts of each size. This confirms psychological studies showing that humans have a more difficult time quantifying abundances of subgroups when confronted with well-mixed groups. In the Yuba, mean grain size decreased downstream, as is typical for an alluvial river. When averaged by reach, mean grain size and bed slope were correlated with an r2 of 0.95. At the morphological unit (MU) scale, eight in-channel bed MU types had an r2 of 0.90 between mean

  5. Experimental results on the enhanced backscatter phenomenon and its dynamics

    NASA Astrophysics Data System (ADS)

    Wu, Chensheng; Nelson, William; Ko, Jonathan; Davis, Christopher C.

    2014-10-01

    Enhanced backscatter effects have long been predicted theoretically and experimentally demonstrated. The reciprocity of a turbulent channel generates a group of paired rays with identical trajectory and phase information that leads to a region in phase space with double intensity and scintillation index. Though simulation work based on phase screen models has demonstrated the existence of the phenomenon, few experimental results have been published describing its characteristics, and possible applications of the enhanced backscatter phenomenon are still unclear. With the development of commercially available high powered lasers and advanced cameras with high frame rates, we have successfully captured the enhanced backscatter effects from different reflection surfaces. In addition to static observations, we have also tilted and pre-distorted the transmitted beam at various frequencies to track the dynamic properties of the enhanced backscatter phenomenon to verify its possible application in guidance and beam and image correction through atmospheric turbulence. In this paper, experimental results will be described, and discussions on the principle and applications of the phenomenon will be included. Enhanced backscatter effects are best observed in certain levels of turbulence (Cn 2≍10-13 m-2/3), and show significant potential for providing self-guidance in beam correction that doesn't introduce additional costs (unlike providing a beacon laser). Possible applications of this phenomenon include tracking fast moving object with lasers, long distance (>1km) alignment, and focusing a high-power corrected laser beam over long distances.

  6. Experimental results from an airborne static Fourier transform imaging spectrometer.

    PubMed

    Ferrec, Yann; Taboury, Jean; Sauer, Hervé; Chavel, Pierre; Fournet, Pierre; Coudrain, Christophe; Deschamps, Joël; Primot, Jérôme

    2011-10-20

    A high étendue static Fourier transform spectral imager has been developed for airborne use. This imaging spectrometer, based on a Michelson interferometer with rooftop mirrors, is compact and robust and benefits from a high collection efficiency. Experimental airborne images were acquired in the visible domain. The processing chain to convert raw images to hyperspectral data is described, and airborne spectral images are presented. These experimental results show that the spectral resolution is close to the one expected, but also that the signal to noise ratio is limited by various phenomena (jitter, elevation fluctuations, and one parasitic image). We discuss the origin of those limitations and suggest solutions to circumvent them. PMID:22015418

  7. On collisional disruption - Experimental results and scaling laws

    NASA Technical Reports Server (NTRS)

    Davis, Donald R.; Ryan, Eileen V.

    1990-01-01

    Both homogeneous and inhomogeneous targets have been addressed by the present experimental consideration of the impact strengths, fragment sizes, and fragment velocities generated by cement mortar targets whose crushing strengths vary by an order of magnitude, upon impact of projectiles in the velocity range of 50-5700 m/sec. When combined with additional published data, dynamic impact strength is found to correlate with quasi-static material strengths for materials ranging in character from basalt to ice; two materials not following this trend, however, are weak mortar and clay targets. Values consistent with experimental results are obtainable with a simple scaling algorithm based on impact energy, material properties, and collisional strain rate.

  8. Design and experimental results for the S814 airfoil

    SciTech Connect

    Somers, D.M.

    1997-01-01

    A 24-percent-thick airfoil, the S814, for the root region of a horizontal-axis wind-turbine blade has been designed and analyzed theoretically and verified experimentally in the low-turbulence wind tunnel of the Delft University of Technology Low Speed Laboratory, The Netherlands. The two primary objectives of high maximum lift, insensitive to roughness, and low profile drag have been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results show good agreement with the exception of maximum lift which is overpredicted. Comparisons with other airfoils illustrate the higher maximum lift and the lower profile drag of the S814 airfoil, thus confirming the achievement of the objectives.

  9. Numerical prediction of freezing fronts in cryosurgery: comparison with experimental results.

    PubMed

    Fortin, André; Belhamadia, Youssef

    2005-08-01

    Recent developments in scientific computing now allow to consider realistic applications of numerical modelling to medicine. In this work, a numerical method is presented for the simulation of phase change occurring in cryosurgery applications. The ultimate goal of these simulations is to accurately predict the freezing front position and the thermal history inside the ice ball which is essential to determine if cancerous cells have been completely destroyed. A semi-phase field formulation including blood flow considerations is employed for the simulations. Numerical results are enhanced by the introduction of an anisotropic remeshing strategy. The numerical procedure is validated by comparing the predictions of the model with experimental results. PMID:16298846

  10. Comparison of Calculated and Experimental Results for a Boiling/Condensing Experimental Facility

    SciTech Connect

    Carbajo, Juan J; McDuffee, Joel Lee; Felde, David K

    2016-01-01

    A new experimental facility for materials irradiation and testing at the Oak Ridge National Laboratory (ORNL) High Flux Isotope Reactor (HFIR) is being developed. Details of this facility have been presented before [1, 2]. A prototype of this facility, the Thermo-Syphon Test Loop (TSTL) has been built and experimental data have been obtained and analyzed [3, 4]. Pre-test calculations for this facility with the RELAP5-3D code [5] have been presented previously [6] as well as other calculations [7, 8] with the TRACE code [9]. The results of both codes were very different [7]. RELAP5-3D predicted much higher pressures and temperatures than TRACE. This paper compares calculated results with the TSTL experimental data.

  11. Can Community Health Workers Report Accurately on Births and Deaths? Results of Field Assessments in Ethiopia, Malawi and Mali

    PubMed Central

    Silva, Romesh; Amouzou, Agbessi; Munos, Melinda; Marsh, Andrew; Hazel, Elizabeth; Victora, Cesar; Black, Robert; Bryce, Jennifer

    2016-01-01

    Introduction Most low-income countries lack complete and accurate vital registration systems. As a result, measures of under-five mortality rates rely mostly on household surveys. In collaboration with partners in Ethiopia, Ghana, Malawi, and Mali, we assessed the completeness and accuracy of reporting of births and deaths by community-based health workers, and the accuracy of annualized under-five mortality rate estimates derived from these data. Here we report on results from Ethiopia, Malawi and Mali. Method In all three countries, community health workers (CHWs) were trained, equipped and supported to report pregnancies, births and deaths within defined geographic areas over a period of at least fifteen months. In-country institutions collected these data every month. At each study site, we administered a full birth history (FBH) or full pregnancy history (FPH), to women of reproductive age via a census of households in Mali and via household surveys in Ethiopia and Malawi. Using these FBHs/FPHs as a validation data source, we assessed the completeness of the counts of births and deaths and the accuracy of under-five, infant, and neonatal mortality rates from the community-based method against the retrospective FBH/FPH for rolling twelve-month periods. For each method we calculated total cost, average annual cost per 1,000 population, and average cost per vital event reported. Results On average, CHWs submitted monthly vital event reports for over 95 percent of catchment areas in Ethiopia and Malawi, and for 100 percent of catchment areas in Mali. The completeness of vital events reporting by CHWs varied: we estimated that 30%-90% of annualized expected births (i.e. the number of births estimated using a FPH) were documented by CHWs and 22%-91% of annualized expected under-five deaths were documented by CHWs. Resulting annualized under-five mortality rates based on the CHW vital events reporting were, on average, under-estimated by 28% in Ethiopia, 32% in

  12. Comparison of computational and experimental results for a supercritical airfoil

    NASA Technical Reports Server (NTRS)

    Rivers, Melissa B.; Wahls, Richard A.

    1994-01-01

    A computational investigation was performed to study the flow over a supercritical airfoil model. Solutions were obtained for steady-state transonic flow conditions using a thin-layer Navier-Stokes flow solver. The results from this computational study were compared with time-averaged experimental data obtained over a wide Reynolds number range at transonic speeds in the Langley 0.3-Meter Transonic Cryogenic Tunnel. Comparisons were made at a nominal Mach number of 0.72 and at Reynolds numbers ranging from 6 x 10(exp 6) to 35 x 10(exp 6).

  13. Large aperture spatial heterodyne imaging spectrometer: Principle and experimental results

    NASA Astrophysics Data System (ADS)

    Xiangli, Bin; Cai, Qisheng; Du, Shusong

    2015-12-01

    A large aperture spatial heterodyne imaging spectrometer (LASHIS) is proposed. It is a kind of pushbroom Fourier transform ultraspectral imager with no moving parts. This imaging spectrometer, based on a Sagnac lateral shearing interferometer combined with a pair of gratings, has the advantages of high spectral resolution, high throughput and robustness. The principle of LASHIS and its spectral retrieval method are introduced. The processing chain to convert raw images to ultraspectral datacube is also described. Experimental results demonstrate the high resolving power of LASHIS with the emission spectrum of a low pressure sodium lamp.

  14. Experimental and simulational result multipactors in 112 MHz QWR injector

    SciTech Connect

    Xin, T.; Ben-Zvi, I.; Belomestnykh, S.; Brutus, J. C.; Skaritka, J.; Wu, Q.; Xiao, B.

    2015-05-03

    The first RF commissioning of 112 MHz QWR superconducting electron gun was done in late 2014. The coaxial Fundamental Power Coupler (FPC) and Cathode Stalk (stalk) were installed and tested for the first time. During this experiment, we observed several multipacting barriers at different gun voltage levels. The simulation work was done within the same range. The comparison between the experimental observation and the simulation results are presented in this paper. The observations during the test are consisted with the simulation predictions. We were able to overcome most of the multipacting barriers and reach 1.8 MV gun voltage under pulsed mode after several round of conditioning processes.

  15. Single And Double Pulse Irradiation And Comparison With Experimental Results

    SciTech Connect

    Fornarini, L.; Fantoni, R.; Colao, F.; Santagata, A.; Teghil, R.

    2009-09-27

    A theoretical model of laser ablation has been previously developed and applied to Laser Induced Breakdown Spectroscopy (LIBS) analysis of bronzes with the aim to improve quantitative results and to focus on problems arising in the interpretation of experimental data. The model describes laser-solid matter interaction, plume expansion, plasma formation and laser-plasma interaction. A two temperature approach has been also introduced to take into account the initial temperature dynamics of the alloy surface upon ultra-short laser irradiation. We examined various target compositions, typical of archaeological artworks, and different laser characteristics such as wavelength (355 nm, 530 nm, 1064 nm) and pulse duration (8 ns, 250 fs). In this work, the model has been extended to simulate double pulse LIBS configuration in order to clarify the mechanism involved in the process and for better interpreting the experimental data. Plasma composition, relevant parameters (temperature, electron density) and their kinetic evolutions have been measured. Results have been compared with the simulation obtained using the same irradiation conditions and set of targets.

  16. Some new experimental results on the Zr Nb Fe system

    NASA Astrophysics Data System (ADS)

    Ramos, C.; Saragovi, C.; Granovsky, M. S.

    2007-06-01

    The scope of this study is the identification and characterization of intermetallic phases and their binary and ternary fields in the Zr-Nb-Fe phase diagram. A construction of the central region of the phase diagram at 900 °C was proposed using new experimental results obtained by optical and scanning electron microscopies, X-ray diffraction and microprobe analysis. In addition to the well-known Laves C15-type (ZrNb)Fe 2 phase (the polytypic C14 and C36 structures were not detected in the studied compositions), another Laves C14-type phase was found (Zr(NbFe) 2). Watson and Bennett maps helped to predict the occurrence of both of these phases. Moreover, the validity of the Pettifor prediction model for Laves phases in pseudobinary systems with transition elements was checked, verifying the obtained experimental results in the Zr-Nb-Fe system. On the other hand it was determined that the Zr-Nb-Fe ternary system at 900 °C, as it happens in the binary Zr-Nb system, would have a miscibility gap (β-Zr + β-Nb) in the 25-70 at.% Nb composition range, accepting up to 3 at.% Fe approximately.

  17. Atmospheric turbulence correction using digital holographic detection: experimental results.

    PubMed

    Marron, Joseph C; Kendrick, Richard L; Seldomridge, Nathan; Grow, Taylor D; Höft, Thomas A

    2009-07-01

    The performance of long distance imaging systems is typically degraded by phase errors imparted by atmospheric turbulence. In this paper we apply coherent imaging methods to determine, and remove, these phase errors by digitally processing coherent recordings of the image data. In this manner we are able to remove the effects of atmospheric turbulence without needing a conventional adaptive optical system. Digital holographic detection is used to record the coherent, complex-valued, optical field for a series of atmospheric and object realizations. Correction of atmospheric phase errors is then based on maximizing an image sharpness metric to determine the aberrations present and correct the underlying image. Experimental results that demonstrate image recovery in the presence of turbulence are presented. Results obtained with severe turbulence that gives rise to anisoplanatism are also presented. PMID:19582079

  18. Electrical and thermal behavior of unsaturated soils: experimental results

    NASA Astrophysics Data System (ADS)

    Nouveau, Marie; Grandjean, Gilles; Leroy, Philippe; Philippe, Mickael; Hedri, Estelle; Boukcim, Hassan

    2016-05-01

    When soil is affected by a heat source, some of its properties are modified, and in particular, the electrical resistivity due to changes in water content. As a result, these changes affect the thermal properties of soil, i.e., its thermal conductivity and diffusivity. We experimentally examine the changes in electrical resistivity and thermal conductivity for four soils with different grain size distributions and clay content over a wide range of temperatures, from 20 to 100 °C. This temperature range corresponds to the thermal conditions in the vicinity of a buried high voltage cable or a geothermal system. Experiments were conducted at the field scale, at a geothermal test facility, and in the laboratory using geophysical devices and probing systems. The results show that the electrical resistivity decreases and the thermal conductivity increases with temperature up to a critical temperature depending on soil types. At this critical temperature, the air volume in the pore space increases with temperature, and the resulting electrical resistivity also increases. For higher temperatures , the thermal conductivity increases sharply with temperature up to a second temperature limit. Beyond it, the thermal conductivity drops drastically. This limit corresponds to the temperature at which most of the water evaporates from the soil pore space. Once the evaporation is completed, the thermal conductivity stabilizes. To explain these experimental results, we modeled the electrical resistivity variations with temperature and water content in the temperature range 20 - 100°C, showing that two critical temperatures influence the main processes occurring during heating at temperatures below 100 °C.

  19. Gradual ordering in mollusk shell nacre: theoretical modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Coppersmith, Susan N.

    2013-03-01

    Biominerals have attracted the attention of materials scientists, biologists, and mineralogists as well as physicists because of their remarkable mechanical properties and incompletely elucidated formation mechanisms. Nacre, or mother-of-pearl, is a layered biomineral composite that is widely studied because of its self-assembled, efficient and accurately ordered architecture results in remarkable resistance to fracture. New experimental tools enable us to obtain new information about the organization and structure of the mineral tablets in nacre. Our experimental and theoretical investigations yield strong evidence that orientational ordering of these tablets is the result of dynamical self-organization. This work was supported by NSF award CHE&DMR-0613972, DOE award DE-FG02-07ER15899, UW-Graduate School Vilas Award to P.U.P.A. Gilbert, and NSF awards DMR-0209630 and DMR-0906951 to SNC.

  20. Non-shock initiation model for explosive families : experimental results.

    SciTech Connect

    Anderson, Mark U.; Jensen, Charles B.; Todd, Steven N.; Hugh, Chance G.; Caipen, Terry L.

    2010-03-01

    The 'DaMaGe-Initiated-Reaction' (DMGIR) computational model has been developed to predict the response of high explosives to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of a reaction in the explosive, and its growth to detonation. Specifically designed experiments were used to study the initiation process of each explosive family with embedded shock sensors and optical diagnostics. The experimental portion of this model development began with a study of PBXN-5 to develop DMGIR model coefficients for the rigid plastic bonded family, followed by studies of the cast, and bulk-moldable explosive families. The experimental results show an initiation mechanism that is related to input energy and material damage, with well defined initiation thresholds for each explosive family. These initiation details will extend the predictive capability of the DMGIR model from the rigid family into the cast and bulk-moldable families.

  1. Registration of multimodal brain images: some experimental results

    NASA Astrophysics Data System (ADS)

    Chen, Hua-mei; Varshney, Pramod K.

    2002-03-01

    Joint histogram of two images is required to uniquely determine the mutual information between the two images. It has been pointed out that, under certain conditions, existing joint histogram estimation algorithms like partial volume interpolation (PVI) and linear interpolation may result in different types of artifact patterns in the MI based registration function by introducing spurious maxima. As a result, the artifacts may hamper the global optimization process and limit registration accuracy. In this paper we present an extensive study of interpolation-induced artifacts using simulated brain images and show that similar artifact patterns also exist when other intensity interpolation algorithms like cubic convolution interpolation and cubic B-spline interpolation are used. A new joint histogram estimation scheme named generalized partial volume estimation (GPVE) is proposed to eliminate the artifacts. A kernel function is involved in the proposed scheme and when the 1st order B-spline is chosen as the kernel function, it is equivalent to the PVI. A clinical brain image database furnished by Vanderbilt University is used to compare the accuracy of our algorithm with that of PVI. Our experimental results show that the use of higher order kernels can effectively remove the artifacts and, in cases when MI based registration result suffers from the artifacts, registration accuracy can be improved significantly.

  2. Physical mechanism of comet outbursts - An experimental result

    NASA Technical Reports Server (NTRS)

    Hartmann, William K.

    1993-01-01

    Attention is given to an experimental investigation of the physical mechanism of comet outbursts which is consistent with the general picture of mantle presence on comets and clarifies the relation of mantles to eruptive activity. The experiment and closeup observation of Comet P/Halley suggest a result different from most mathematical models in that the release of gas pressure does not occur only from uniform gas flow out of the entire surface. In some active comets near perihelion within a few AU of the sun, gas production rates and disturbance of the surface may be so high that the outflow is nearly continuous, with the regolith being entirely stripped away, as in many of the models. The present model provides a cyclic eruption and recharge mechanism which is lacking in most other models.

  3. Beta decay and the origins of biological chirality - Experimental results

    NASA Technical Reports Server (NTRS)

    Gidley, D. W.; Rich, A.; Van House, J.; Zitzewitz, P. W.

    1982-01-01

    Preliminary experimental results are presented of an investigation of the possible role of preferential radiolysis by electrons emitted in the beta decay of radionuclides, a parity-nonconserving process, in the universal causation of the optical activity of biological compounds. Experiments were designed to measure the asymmetry in the production of triplet positronium upon the bombardment of an amino acid powder target by a collimated beam of positrons as positron helicity or target chirality is reversed. No asymmetry down to a level of 0.0007 is found in experiments on the D and L forms of cystine and tryptophan, indicating an asymmetry in positronium formation cross section of less than 0.01, while an asymmetry of 0.0031 is found for leucine, corresponding to a formation cross section asymmetry of about 0.04

  4. Robotic follower experimentation results: ready for FCS increment I

    NASA Astrophysics Data System (ADS)

    Jaczkowski, Jeffrey J.

    2003-09-01

    Robotics is a fundamental enabling technology required to meet the U.S. Army's vision to be a strategically responsive force capable of domination across the entire spectrum of conflict. The U. S. Army Research, Development and Engineering Command (RDECOM) Tank Automotive Research, Development & Engineering Center (TARDEC), in partnership with the U.S. Army Research Laboratory, is developing a leader-follower capability for Future Combat Systems. The Robotic Follower Advanced Technology Demonstration (ATD) utilizes a manned leader to provide a highlevel proofing of the follower's path, which operates with minimal user intervention. This paper will give a programmatic overview and discuss both the technical approach and operational experimentation results obtained during testing conducted at Ft. Bliss, New Mexico in February-March 2003.

  5. Object impedance control for cooperative manipulation - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Schneider, Stanley A.; Cannon, Robert H., Jr.

    1989-01-01

    The dynamic control module being developed in the Dynamic and Strategic Control of Cooperative Manipulators (DASCCOM) project at the Stanford University Aerospace Robotics Laboratory is described. First, the cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. Next, a control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to the strategic controller. Experimental results for a dual two-link arm robotic system are presented to verify the controllers performance, for both free-motion slews and environmental contact.

  6. Preliminary Experimental Results from a MARS Micro-CT System

    PubMed Central

    He, Peng; Yu, Hengyong; Thayer, Patrick; Jin, Xin; Xu, Qiong; Bennett, James; Tappenden, Rachael; Wei, Biao; Goldstein, Aaron; Renaud, Peter; Butler, Anthony; Butler, Phillip; Wang, Ge

    2013-01-01

    The Medipix All Resolution System (MARS) system is a commercial spectral/multi-energy micro-CT scanner designed and assembled by the MARS Bioimaging, Ltd. in New Zealand. This system utilizes the state-of-the-art Medipix photon-counting, energy-discriminating detector technology developed by a collaboration based at European Organization for Nuclear Research (CERN). In this paper, we report our preliminary experimental results using this system, including geometrical alignment, photon energy characterization, protocol optimization, and spectral image reconstruction. We produced our scan datasets with a multi-material phantom, and then applied ordered subset-simultaneous algebraic reconstruction technique (OS-SART) to reconstruct images in different energy ranges and principal component analysis (PCA) to evaluate spectral deviation between the energy ranges. PMID:22635175

  7. Selected experimental results from heavy-ion collisions at LHC

    DOE PAGESBeta

    Singh, Ranbir; Kumar, Lokesh; Netrakanti, Pawan Kumar; Mohanty, Bedangadas

    2013-01-01

    We reviewmore » a subset of experimental results from the heavy-ion collisions at the Large Hadron Collider (LHC) facility at CERN. Excellent consistency is observed across all the experiments at the LHC (at center of mass energysNN=2.76 TeV) for the measurements such as charged particle multiplicity density, azimuthal anisotropy coefficients, and nuclear modification factor of charged hadrons. Comparison to similar measurements from the Relativistic Heavy Ion Collider (RHIC) at lower energy (sNN=200 GeV) suggests that the system formed at LHC has a higher energy density and larger system size and lives for a longer time. These measurements are compared to model calculations to obtain physical insights on the properties of matter created at the RHIC and LHC.« less

  8. Solving and Learning Soft Temporal Constraints: Experimental Setting and Results

    NASA Technical Reports Server (NTRS)

    Rossi, F.; Sperduti, A.; Venable, K. B.; Khatib, L.; Morris, P.; Morris, R.; Clancy, Daniel (Technical Monitor)

    2002-01-01

    Soft temporal constraints problems allow to describe in a natural way scenarios where events happen over time and preferences are associated to event distances and durations. However, sometimes such local preferences are difficult to set, and it may be easier instead to associate preferences to some complete solutions of the problem. Machine learning techniques can be useful in this respect. In this paper we describe two solvers (one more general and the other one more efficient) for tractable subclasses of soft temporal problems, and we show some experimental results. The random generator used to build the problems on which tests are performed is also described. We also compare the two solvers highlighting the tradeoff between performance and representational power. Finally, we present a learning module and we show its behavior on randomly-generated examples.

  9. Experimental results to study astrophysical plasma jets using Intense Lasers

    NASA Astrophysics Data System (ADS)

    Loupias, B.; Gregory, C. D.; Falize, E.; Waugh, J.; Seiichi, D.; Pikuz, S.; Kuramitsu, Y.; Ravasio, A.; Bouquet, S.; Michaut, C.; Barroso, P.; Rabec Le Gloahec, M.; Nazarov, W.; Takabe, H.; Sakawa, Y.; Woolsey, N.; Koenig, M.

    2009-08-01

    We present experimental results of plasma jet, interacted with an ambient medium, using intense lasers to investigate the complex features of astrophysical jets. This experiment was performed in France at the LULI facility, Ecole Polytechnique, using one long pulse laser to generate the jet and a short pulse laser to probe it by proton radiography. A foam filled cone target was used to generate high velocity plasma jet, and a gas jet nozzle produced the well known ambient medium. Using visible pyrometry and interferometry, we were able to measure the jet velocity and electronic density. We get a panel of measurements at various gas density and time delay. From these measurements, we could underline the growth of a perturbed shape of the jet interaction with the ambient medium. The reason of this last observation is still in debate and will be presented in the article.

  10. Arm-free paraplegic standing--Part II: Experimental results.

    PubMed

    Matjacić, Z; Bajd, T

    1998-06-01

    In Part I, we proposed an approach for restoring unsupported standing to thoracic-level paraplegics. The theoretical analysis and simulation of an underactuated double inverted pendulum, representing the standing subject, showed that arm-free standing might be achieved. Here in Part II, we present the mechanical apparatus which we used in our experiments and experimental results from tests of the balance-control strategy. We demonstrate that an intact and a paraplegic subject could perform quiet standing with the ankle stiffness set to 8 Nm/degree or even less (the intact subject). Both were also able to recover from disturbances, imposed by the artificial ankle joint of the apparatus. Introducing cognitive auditory feedback greatly improved the standing abilities of both subjects. PMID:9631321

  11. Object impedance control for cooperative manipulation - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Schneider, Stanley A.; Cannon, Robert H., Jr.

    1992-01-01

    This paper presents the dynamic control module of the Dynamic and Strategic Control of Cooperating Manipulators (DASCCOM) project at Stanford University's Aerospace Robotics Laboratory. First, the cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. Next, a control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to higher level strategic control modules. Experimental results from a dual two-link-arm robotic system are used to compare the object impedance controller with other strategies, both for free-motion slews and environmental contact.

  12. Experimental Results of Rover-Based Coring and Caching

    NASA Technical Reports Server (NTRS)

    Backes, Paul G.; Younse, Paulo; DiCicco, Matthew; Hudson, Nicolas; Collins, Curtis; Allwood, Abigail; Paolini, Robert; Male, Cason; Ma, Jeremy; Steele, Andrew; Conrad, Pamela G.

    2011-01-01

    Experimental results are presented for experiments performed using a prototype rover-based sample coring and caching system. The system consists of a rotary percussive coring tool on a five degree-of-freedom manipulator arm mounted on a FIDO-class rover and a sample caching subsystem mounted on the rover. Coring and caching experiments were performed in a laboratory setting and in a field test at Mono Lake, California. Rock abrasion experiments using an abrading bit on the coring tool were also performed. The experiments indicate that the sample acquisition and caching architecture is viable for use in a 2018 timeframe Mars caching mission and that rock abrasion using an abrading bit may be feasible in place of a dedicated rock abrasion tool.

  13. Integrated radar-camera security system: experimental results

    NASA Astrophysics Data System (ADS)

    Zyczkowski, M.; Palka, N.; Trzcinski, T.; Dulski, R.; Kastek, M.; Trzaskawka, P.

    2011-06-01

    The nature of the recent military conflicts and terrorist attacks along with the necessity to protect bases, convoys and patrols have made a serious impact on the development of more effective security systems. Current widely-used perimeter protection systems with zone sensors will soon be replaced with multi-sensor systems. Multi-sensor systems can utilize day/night cameras, IR uncooled thermal cameras, and millimeter-wave radars which detect radiation reflected from targets. Ranges of detection, recognition and identification for all targets depend on the parameters of the sensors used and of the observed scene itself. In this paper two essential issues connected with multispectral systems are described. We will focus on describing the autonomous method of the system regarding object detection, tracking, identification, localization and alarm notifications. We will also present the possibility of configuring the system as a stationary, mobile or portable device as in our experimental results.

  14. Direct Numerical Simulation of Liquid Nozzle Spray with Comparison to Shadowgraphy and X-Ray Computed Tomography Experimental Results

    NASA Astrophysics Data System (ADS)

    van Poppel, Bret; Owkes, Mark; Nelson, Thomas; Lee, Zachary; Sowell, Tyler; Benson, Michael; Vasquez Guzman, Pablo; Fahrig, Rebecca; Eaton, John; Kurman, Matthew; Kweon, Chol-Bum; Bravo, Luis

    2014-11-01

    In this work, we present high-fidelity Computational Fluid Dynamics (CFD) results of liquid fuel injection from a pressure-swirl atomizer and compare the simulations to experimental results obtained using both shadowgraphy and phase-averaged X-ray computed tomography (CT) scans. The CFD and experimental results focus on the dense near-nozzle region to identify the dominant mechanisms of breakup during primary atomization. Simulations are performed using the NGA code of Desjardins et al (JCP 227 (2008)) and employ the volume of fluid (VOF) method proposed by Owkes and Desjardins (JCP 270 (2013)), a second order accurate, un-split, conservative, three-dimensional VOF scheme providing second order density fluxes and capable of robust and accurate high density ratio simulations. Qualitative features and quantitative statistics are assessed and compared for the simulation and experimental results, including the onset of atomization, spray cone angle, and drop size and distribution.

  15. Experimental Progress and Results of a Visible Nulling Coronagraph

    NASA Technical Reports Server (NTRS)

    Samuele, Rocco; Wallace, J. Kent; Schmidtlin, Edouard; Shao, Mike; Levine, B. Martin; Fregoso, Santos

    2007-01-01

    The crux of visible exoplanet detection is overcoming significant star-planet contrast ratios on the order of 10(exp -7) to 10(exp -10)-at very small angular separations. We are developing an interferometric nulling coronagraph designed to achieve a 10(exp -6) contrast ratio at a working science bandpass of 20% visible light. Achieving large, broadband suppression requires a pseudo-achromatic phase flip, while maintaining a strict error budget. Recent results from our nulling interferometer testbed yield contrast ratios at the 1.05x10(exp -6) level, with a 15% visible bandpass. This result is at 65% of our final bandpass requirement, although limitations of our current configuration make major hardware changes essential to broadening the bandpass. We make the argument that broadening the bandpass should not necessarily adversely affect the null depth until beyond the 20% visible light level. Using the same setup we are able to reach monochromatic null depths of 1.11x10(exp -7) (?= 638 nm)averaged over three seconds. This paper will describe our experimental approach for achieving deep broadband nulls, as well as error considerations and limitations, and the most recent results for our nulling coronagraph testbed.

  16. Experimental Results for Titan Aerobot Thermo-Mechanical Subsystem Development

    NASA Technical Reports Server (NTRS)

    Hall, Jeffrey L.; Jones, J. A.; Kerzhanovich, V. V.; Lachenmeier, T.; Mahr, P.; Pauken, M.; Plett, G. A.; Smith, L.; VanLuvender, M. L.; Yavrouian, A. H.

    2006-01-01

    This paper describes experimental results from a development program focused in maturing Titan aerobot technology in the areas of mechanical and thermal subsystems. Results from four key activities are described: first, a cryogenic balloon materials development program involving coupon and cylinder tests and culminating in the fabrication and testing of an inflated 4.6 m long prototype blimp at 93 K; second, a combined lab experiment and numerical simulation effort to assess potential problems resulting from radioisotope thermal generator waste heat generation near an inflated blimp; third, an aerial deployment and inflation development program consisting of laboratory and helicopter drop tests on a near full scale (11 m long) prototype blimp; and fourth, a proof of concept experiment demonstrating the viability of using a mechanically steerable high gain antenna on a floating blimp to perform direct to Earth telecommunications from Titan. The paper provides details on all of these successful activities and discusses their impact on the overall effort to produce mature systems technology for future Titan aerobot missions.

  17. Internal wave emission from baroclinic jets: experimental results

    NASA Astrophysics Data System (ADS)

    Borcia, Ion D.; Rodda, Costanza; Harlander, Uwe

    2016-04-01

    Large-scale balanced flows can spontaneously radiate meso-scale inertia-gravity waves (IGWs) and are thus in fact unbalanced. While flow-dependent parameterizations for the radiation of IGWs from orographic and convective sources do exist, the situation is less developed for spontaneously emitted IGWs. Observations identify increased IGW activity in the vicinity of jet exit regions. A direct interpretation of those based on geostrophic adjustment might be tempting. However, directly applying this concept to the parameterization of spontaneous imbalance is difficult since the dynamics itself is continuously re-establishing an unbalanced flow which then sheds imbalances by GW radiation. Examining spontaneous IGW emission in the atmosphere and validating parameterization schemes confronts the scientist with particular challenges. Due to its extreme complexity, GW emission will always be embedded in the interaction of a multitude of interdependent processes, many of which are hardly detectable from analysis or campaign data. The benefits of repeated and more detailed measurements, while representing the only source of information about the real atmosphere, are limited by the non-repeatability of an atmospheric situation. The same event never occurs twice. This argues for complementary laboratory experiments, which can provide a more focused dialogue between experiment and theory. Indeed, life cycles are also examined in rotating-annulus laboratory experiments. Thus, these experiments might form a useful empirical benchmark for theoretical and modeling work that is also independent of any sort of subgrid model. In addition, the more direct correspondence between experimental and model data and the data reproducibility makes lab experiments a powerful testbed for parameterizations. Here we show first results from a small rotating annulus experiments and we will further present our new experimental facility to study wave emission from jets and fronts.

  18. Experimental Results from a Resonant Dielectric Laser Accelerator

    NASA Astrophysics Data System (ADS)

    Yoder, Rodney; McNeur, Joshua; Sozer, Esin; Travish, Gil; Hazra, Kiran Shankar; Matthews, Brian; England, Joel; Peralta, Edgar; Wu, Ziran

    2015-04-01

    Laser-powered accelerators have the potential to operate with very large accelerating gradients (~ GV/m) and represent a path toward extremely compact colliders and accelerator technology. Optical-scale laser-powered devices based on field-shaping structures (known as dielectric laser accelerators, or DLAs) have been described and demonstrated recently. Here we report on the first experimental results from the Micro-Accelerator Platform (MAP), a DLA based on a slab-symmetric resonant optical-scale structure. As a resonant (rather than near-field) device, the MAP is distinct from other DLAs. Its cavity resonance enhances its accelerating field relative to the incoming laser fields, which are coupled efficiently through a diffractive optic on the upper face of the device. The MAP demonstrated modest accelerating gradients in recent experiments, in which it was powered by a Ti:Sapphire laser well below its breakdown limit. More detailed results and some implications for future developments will be discussed. Supported in part by the U.S. Defense Threat Reduction Agency (UCLA); U.S. Dept of Energy (SLAC); and DARPA (SLAC).

  19. Breaking the resolution limit: an exciting experimental result

    NASA Astrophysics Data System (ADS)

    Simonetti, Francesco

    2006-03-01

    For more than a century the possibility of imaging the structure of a medium with diffracting wavefields has been limited by the tradeoff between resolution and imaging depth. While long wavelengths can penetrate deep into a medium, the resolution limit precludes the possibility of observing subwavelength structures. Recent progress in microscopy has shown that by exploiting the super-oscillatory properties of evanescent fields, resolution several orders of magnitude smaller than the wavelength can be achieved so leading to Near-field Scanning Optical Microscopy. Based on a similar argument, this paper investigates the possibility of obtaining super resolution in the far-field (here far-field refers to a distance greater than λ, which would enable high resolution imaging at relatively large depth. The theoretical principles which result in the resolution limit are reviewed and a new strategy to overcome it is proposed. An advanced imaging algorithm for linear and two-dimensional array probing systems is presented and its capability of resolving targets as close as λ/3 is demonstrated experimentally, the targets being at several wavelength distance from the array. The results show that the method is superior to conventional techniques such as Synthetic Aperture Focusing, Synthetic Phased Arrays and Time Reversal.

  20. Experimental results of an iodine plasma in PEGASES gridded thruster

    NASA Astrophysics Data System (ADS)

    Grondein, Pascaline; Aanesland, Ane

    2015-09-01

    In the electric gridded thruster PEGASES, both positive and negative ions are expelled after extraction from an ion-ion plasma. This ion-ion plasma is formed downstream a localized magnetic field placed a few centimeters from the ionization region, trapping and cooling down the electron to allow a better attachment to an electronegative gas. For this thruster concept, iodine has emerged as the most attractive option. Heavy, under diatomic form and therefore good for high thrust, its low ionization threshold and high electronegativity lead to high ion-ion densities and low RF power. After the proof-of-concept of PEGASES using SF6 as propellant, we present here experimental results of an iodine plasma studied inside PEGASES thruster. At solid state at standard temperature and pressure, iodine is heated to sublimate, then injected inside the chamber where the neutral gas is heated and ionized. The whole injection system is heated to avoid deposition on surfaces and a mass flow controller allows a fine control on the neutral gas mass flow. A 3D translation stage inside the vacuum chamber allows volumetric plasma studies using electrostatic probes. The results are also compared with the global model dedicated to iodine as propellant for electric gridded thrusters. This work has been done within the LABEX Plas@par project, and received financial state aid managed by the Agence Nationale de la Recherche, as part of the programme ``Investissements d'avenir.''

  1. Experimental Results of Guided Wave Travel Time Tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Mast, Arjan; Bloom, Joost

    2010-02-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Both economical and social requirements are pushing the industry to even higher levels of availability, reliability and safety of installations. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation is an interesting addition to the current method of periodic inspections reducing uncertainty and extending inspection intervals. Guided wave travel time tomography is a promising method to monitor the wall thickness quantitatively over large areas. Obviously the robustness and reliability of such a monitoring system is of paramount importance. Laboratory experiments have been carried out on a 10″ pipe with a nominal wall thickness of 8 mm. Multiple, inline defects have been created with a realistic morphology. The depth of the defects was increased stepwise from 0.5 mm to 2 mm. Additionally the influences of the presence of liquid inside the pipe and surface roughness have been evaluated as well. Experimental results show that this method is capable of providing quantitative wall thickness information over a distance of 4 meter, with a sufficient accuracy such that results can be used for trending. The method has no problems imaging multiple defects.

  2. Experimental results of a single emittance compensation solenoidal magnet

    SciTech Connect

    Palmer, D.T.; Miller, R.H.; Wang, X.J.; Ben-Zvi, I.; Skaritka, J.

    1997-07-01

    A new iron dominated single emittance compensation solenoidal magnet was designed to be integrated with the BNL/SLAC/UCLA 1.6 cell S-Band Photocathode rf Gun. This emittance compensated photoinjector is now in operation at the Brookhaven Accelerator Test Facility. It has produced a 0.329 {+-} 0.012 pC, {tau}{sub 95%} = 10.9 psec electron bunches with a normalized rms transverse emittance of {epsilon}{sub n,rms} = 1.17 {+-} 0.16 {pi} mm mrad. POISSON field maps were used with PARMELA to optimize the emittance compensation solenoidal magnet design. Magnetic field measurements show that at the cathode plane B{sub z} {le} 10 G for a peak magnetic field of B{sub z,max} = 3 kG. Which is in agreement with POISSON simulation. A single emittance compensation solenoidal magnet will produces an initial angular momentum of the electron bunch that manifests itself in a initial magnetic emittance term that cannot be eliminated. This magnetic emittance {epsilon}{sub n,rms}{sup mag} scales as 0.010 {pi} mm mrad/G as the cathode, which is in agreement with PARMELA simulations. Experimental beam dynamics results are presented that shows relative angular rotation and spot size as a function of cathode magnetic field. These results are compared to theory.

  3. Theoretical and Experimental Results Regarding LENR/CF

    SciTech Connect

    Robert W. Bass; Wm. Stan Gleeson

    2000-11-12

    We challenge the predominant view that low-energy nuclear reactions (LENRs) are prohibited by standard quantum mechanics (QM). This view, supposedly based on standard nuclear theory, need not apply in condensed-matter environments. These considerations indicate that seemingly novel experimental evidence of rapid aneutronic bulk-process transmutation, at extraordinarily low-energy levels, in a simple electrochemical reactor, can occur. This explains: (a) induced rapid decay of radioactive thorium into stable nuclides, e.g., Cu and (b) resulting, anomalous distribution of Cu isotopes. We reexamine arguments of Peebles cited as evidence that standard QM 'forbids' cold fusion (CF). We note oversimplifications in those and present an alternative, more sophisticated calculation (see Bass, Refs. 3 through 8) demonstrating that conventional wisdom about impenetrability of the 'Coulomb barrier' fails as a result of periodic-order-induced resonance. We also examine empirical evidence. In three independent tests of an LENR electrolysis cell, using different I-V-T (current/voltage/time) protocols, the percentage of radiation reduction (RR) transmutation achieved {eta}=[23{percent}, 50{percent}, 83{percent}] versus expended energy E=[0.6535, 32.5, 74.6] (Watt-hours), obtained by numerical integration of recorded product I{center_dot}V for processing time T, provides near-perfect straight-line correlation: {eta}={alpha}{center_dot}E + {eta}{sub 0}, {alpha}=0.8105, {eta}{sub 0}=22.888, (0.65 < E < 0.75).

  4. Recent experimental results of KSTAR RF heating and current drive

    SciTech Connect

    Wang, S. J. Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-10

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  5. Recent experimental results of KSTAR RF heating and current drive

    NASA Astrophysics Data System (ADS)

    Wang, S. J.; Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G.

    2015-12-01

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  6. Experimental Results of Hydrate Reservoir Destabilization Through Heating

    NASA Astrophysics Data System (ADS)

    Leeman, J.; Hornbach, M. J.; Elwood-Madden, M.; Phelps, T. J.; Rawn, C. J.

    2011-12-01

    Gas clathrate reservoirs have been considered as possible sources of energy, as hazards to deep water drilling operations, and as contributors to global climate change. Clathrate destabilization may occur through depressurization of the reservoir, addition of chemical inhibitors, or heating the reservoir. Meso-scale heat conduction experiments were conducted in the Seafloor Process Simulator (SPS) at Oak Ridge National Laboratory in an attempt to apply experimental constraints to purely numerical models of heat transfer within a nearly isobaric reservoir. A column of saturated sediment was place inside the pressure vessel and pressurized to conditions sufficient to form methane clathrate at seafloor temperatures, while the system remained at room temperature (298K). Once pressurized, the temperature of the vessel was then lowered to approximately 275K, forming pore filling clathrate in the sediment column. Following hydrate formation, heat was supplied to the center of the clathrate reservoir through a hot fluid heat exchanger embedded in the sediment column to dissociate the methane hydrate. Relative changes in temperature within the hydrate-sediment column were monitored with a fiber optic quasi-distributed sensing system (DSS), along with temperature and pressure within the vessel headspace. Using the DSS Plotter analysis software, it was determined that an axis-symmetric section of clathrate was dissociated around the heat exchanger. Clathrate dissociation was accompanied by a small rise in vessel headspace pressure in addition to the expected thermal expansion of the headspace gas. The quantity of heat input to the system was calculated from the drop in fluid temperature as it flowed through the heat exchanger. Increased heat input resulted in an increase in the volume of hydrate dissociated. Clathrate rapidly reformed immediately upon the removal of the heat energy. A simple numerical model has been developed to simulate the heat flow in the system. Early

  7. Impact Flash Physics: Modeling and Comparisons With Experimental Results

    NASA Astrophysics Data System (ADS)

    Rainey, E.; Stickle, A. M.; Ernst, C. M.; Schultz, P. H.; Mehta, N. L.; Brown, R. C.; Swaminathan, P. K.; Michaelis, C. H.; Erlandson, R. E.

    2015-12-01

    Hypervelocity impacts frequently generate an observable "flash" of light with two components: a short-duration spike due to emissions from vaporized material, and a long-duration peak due to thermal emissions from expanding hot debris. The intensity and duration of these peaks depend on the impact velocity, angle, and the target and projectile mass and composition. Thus remote sensing measurements of planetary impact flashes have the potential to constrain the properties of impacting meteors and improve our understanding of impact flux and cratering processes. Interpreting impact flash measurements requires a thorough understanding of how flash characteristics correlate with impact conditions. Because planetary-scale impacts cannot be replicated in the laboratory, numerical simulations are needed to provide this insight for the solar system. Computational hydrocodes can produce detailed simulations of the impact process, but they lack the radiation physics required to model the optical flash. The Johns Hopkins University Applied Physics Laboratory (APL) developed a model to calculate the optical signature from the hot debris cloud produced by an impact. While the phenomenology of the optical signature is understood, the details required to accurately model it are complicated by uncertainties in material and optical properties and the simplifications required to numerically model radiation from large-scale impacts. Comparisons with laboratory impact experiments allow us to validate our approach and to draw insight regarding processes that occur at all scales in impact events, such as melt generation. We used Sandia National Lab's CTH shock physics hydrocode along with the optical signature model developed at APL to compare with a series of laboratory experiments conducted at the NASA Ames Vertical Gun Range. The experiments used Pyrex projectiles to impact pumice powder targets with velocities ranging from 1 to 6 km/s at angles of 30 and 90 degrees with respect to

  8. Design and experimental results of coaxial circuits for gyroklystron amplifiers

    SciTech Connect

    Flaherty, M.K.E.; Lawson, W.; Cheng, J.; Calame, J.P.; Hogan, B.; Latham, P.E.; Granatstein, V.L.

    1994-12-31

    At the University of Maryland high power microwave source development for use in linear accelerator applications continues with the design and testing of coaxial circuits for gyroklystron amplifiers. This presentation will include experimental results from a coaxial gyroklystron that was tested on the current microwave test bed, and designs for second harmonic coaxial circuits for use in the next generation of the gyroklystron program. The authors present test results for a second harmonic coaxial circuit. Similar to previous second harmonic experiments the input cavity resonated at 9.886 GHz and the output frequency was 19.772 GHz. The coaxial insert was positioned in the input cavity and drift region. The inner conductor consisted of a tungsten rod with copper and ceramic cylinders covering its length. Two tungsten rods that bridged the space between the inner and outer conductors supported the whole assembly. The tube produced over 20 MW of output power with 17% efficiency. Beam interception by the tungsten rods resulted in minor damage. Comparisons with previous non-coaxial circuits showed that the coaxial configuration increased the parameter space over which stable operation was possible. Future experiments will feature an upgraded modulator and beam formation system capable of producing 300 MW of beam power. The fundamental frequency of operation is 8.568 GHz. A second harmonic coaxial gyroklystron circuit was designed for use in the new system. A scattering matrix code predicts a resonant frequency of 17.136 GHz and Q of 260 for the cavity with 95% of the outgoing microwaves in the desired TE032 mode. Efficiency studies of this second harmonic output cavity show 20% expected efficiency. Shorter second harmonic output cavity designs are also being investigated with expected efficiencies near 34%.

  9. Numerical predictions and experimental results of a dry bay fire environment.

    SciTech Connect

    Suo-Anttila, Jill Marie; Gill, Walter; Black, Amalia Rebecca

    2003-11-01

    The primary objective of the Safety and Survivability of Aircraft Initiative is to improve the safety and survivability of systems by using validated computational models to predict the hazard posed by a fire. To meet this need, computational model predictions and experimental data have been obtained to provide insight into the thermal environment inside an aircraft dry bay. The calculations were performed using the Vulcan fire code, and the experiments were completed using a specially designed full-scale fixture. The focus of this report is to present comparisons of the Vulcan results with experimental data for a selected test scenario and to assess the capability of the Vulcan fire field model to accurately predict dry bay fire scenarios. Also included is an assessment of the sensitivity of the fire model predictions to boundary condition distribution and grid resolution. To facilitate the comparison with experimental results, a brief description of the dry bay fire test fixture and a detailed specification of the geometry and boundary conditions are included. Overall, the Vulcan fire field model has shown the capability to predict the thermal hazard posed by a sustained pool fire within a dry bay compartment of an aircraft; although, more extensive experimental data and rigorous comparison are required for model validation.

  10. Acoustic analysis in Mudejar-Gothic churches: experimental results.

    PubMed

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. PMID:15957758

  11. Acoustic analysis in Mudejar-Gothic churches: Experimental results

    NASA Astrophysics Data System (ADS)

    Galindo, Miguel; Zamarreño, Teófilo; Girón, Sara

    2005-05-01

    This paper describes the preliminary results of research work in acoustics, conducted in a set of 12 Mudejar-Gothic churches in the city of Seville in the south of Spain. Despite common architectural style, the churches feature individual characteristics and have volumes ranging from 3947 to 10 708 m3. Acoustic parameters were measured in unoccupied churches according to the ISO-3382 standard. An extensive experimental study was carried out using impulse response analysis through a maximum length sequence measurement system in each church. It covered aspects such as reverberation (reverberation times, early decay times), distribution of sound levels (sound strength); early to late sound energy parameters derived from the impulse responses (center time, clarity for speech, clarity, definition, lateral energy fraction), and speech intelligibility (rapid speech transmission index), which all take both spectral and spatial distribution into account. Background noise was also measured to obtain the NR indices. The study describes the acoustic field inside each temple and establishes a discussion for each one of the acoustic descriptors mentioned by using the theoretical models available and the principles of architectural acoustics. Analysis of the quality of the spaces for music and speech is carried out according to the most widespread criteria for auditoria. .

  12. Preliminary Experimental Result of Magnetic Reconnection in Laboratory Plasma

    NASA Astrophysics Data System (ADS)

    Zhang, S. B.; Xie, J. L.; Hu, G. H.; Li, H.; Huang, G. L.; Liu, W. D.

    2011-05-01

    Magnetic reconnection is one of the most important physical processes in astrophysical plasmas. Lots of theoretical works, numerical simulations and observations have been done. Some experimental programs have been activated to investigate the basic mechanisms of magnetic reconnection. In order to investigate the electron dynamic near the electron diffusion region in magnetic reconnection process, an upgrade is accomplished in the LMP (Linear magnetic plasmas) device at University of Science and Technology of China. The magnetic field of reconnection is produced by passing two identical currents axially through two copper plates. Magnetic field and parallel electric field are measured by magnetic probes and emissive probes, respectively. The existence of a large electric field related to the reconnection process is verified. The plasma is driven by electric field and magnetic field, so the magnetic reconnection appears. The magnitude of axial current is found to scale with the number of passing particles. In the configuration of current bars, passing particles are even more and our measured axial current is about 10 A. Magnetic flux doesn't pile up because of the parameter region in our case, which is consistent with the result of numerical simulation.

  13. Experimental results on atomic oxygen corrosion of silver

    NASA Technical Reports Server (NTRS)

    Fromhold, Albert T.

    1988-01-01

    The results of an experimental study of the reaction kinetics of silver with atomic oxygen in 10 degree increments over the temperature range of 0 to 70 C is reported. The silver specimens, of the order of 10,000 A in thickness, were prepared by thermal evaporation onto 3 inch diameter polished silicon wafers. There were later sliced into pieces having surface areas of the order of 1/4 to 1/2 square inch. Atomic oxygen was generated by a gas discharge in a commercial plasmod asher operating in the megahertz frequency range. The sample temperature within the chamber was controlled by means of a thermoelectric unit. Exposure of the silver specimens to atomic oxygen was incremental, with oxide film thickness measurements being carried out between exposures by means of an automated ellipsometer. For the early growth phase, the data can be described satisfactorily by a logarithmic growth law: the oxide film thickness increases as the logarithm of the exposure time. Furthermore, the oxidation process is thermally activated, the rate increasing with increasing temperature. However, the empirical activation energy parameter deduced from Arrhenius plots is quite low, being of the order of 0.1 eV.

  14. Energy-resolved computed tomography: first experimental results

    NASA Astrophysics Data System (ADS)

    Shikhaliev, Polad M.

    2008-10-01

    First experimental results with energy-resolved computed tomography (CT) are reported. The contrast-to-noise ratio (CNR) in CT has been improved with x-ray energy weighting for the first time. Further, x-ray energy weighting improved the CNR in material decomposition CT when applied to CT projections prior to dual-energy subtraction. The existing CT systems use an energy (charge) integrating x-ray detector that provides a signal proportional to the energy of the x-ray photon. Thus, the x-ray photons with lower energies are scored less than those with higher energies. This underestimates contribution of lower energy photons that would provide higher contrast. The highest CNR can be achieved if the x-ray photons are scored by a factor that would increase as the x-ray energy decreases. This could be performed by detecting each x-ray photon separately and measuring its energy. The energy selective CT data could then be saved, and any weighting factor could be applied digitally to a detected x-ray photon. The CT system includes a photon counting detector with linear arrays of pixels made from cadmium zinc telluride (CZT) semiconductor. A cylindrical phantom with 10.2 cm diameter made from tissue-equivalent material was used for CT imaging. The phantom included contrast elements representing calcifications, iodine, adipose and glandular tissue. The x-ray tube voltage was 120 kVp. The energy selective CT data were acquired, and used to generate energy-weighted and material-selective CT images. The energy-weighted and material decomposition CT images were generated using a single CT scan at a fixed x-ray tube voltage. For material decomposition the x-ray spectrum was digitally spilt into low- and high-energy parts and dual-energy subtraction was applied. The x-ray energy weighting resulted in CNR improvement of calcifications and iodine by a factor of 1.40 and 1.63, respectively, as compared to conventional charge integrating CT. The x-ray energy weighting was also applied

  15. Blast-induced biomechanical loading of the rat: an experimental and anatomically accurate computational blast injury model.

    PubMed

    Sundaramurthy, Aravind; Alai, Aaron; Ganpule, Shailesh; Holmberg, Aaron; Plougonven, Erwan; Chandra, Namas

    2012-09-01

    Blast waves generated by improvised explosive devices (IEDs) cause traumatic brain injury (TBI) in soldiers and civilians. In vivo animal models that use shock tubes are extensively used in laboratories to simulate field conditions, to identify mechanisms of injury, and to develop injury thresholds. In this article, we place rats in different locations along the length of the shock tube (i.e., inside, outside, and near the exit), to examine the role of animal placement location (APL) in the biomechanical load experienced by the animal. We found that the biomechanical load on the brain and internal organs in the thoracic cavity (lungs and heart) varied significantly depending on the APL. When the specimen is positioned outside, organs in the thoracic cavity experience a higher pressure for a longer duration, in contrast to APL inside the shock tube. This in turn will possibly alter the injury type, severity, and lethality. We found that the optimal APL is where the Friedlander waveform is first formed inside the shock tube. Once the optimal APL was determined, the effect of the incident blast intensity on the surface and intracranial pressure was measured and analyzed. Noticeably, surface and intracranial pressure increases linearly with the incident peak overpressures, though surface pressures are significantly higher than the other two. Further, we developed and validated an anatomically accurate finite element model of the rat head. With this model, we determined that the main pathway of pressure transmission to the brain was through the skull and not through the snout; however, the snout plays a secondary role in diffracting the incoming blast wave towards the skull. PMID:22620716

  16. LiF TLD-100 as a Dosimeter in High Energy Proton Beam Therapy-Can It Yield Accurate Results?

    SciTech Connect

    Zullo, John R. Kudchadker, Rajat J.; Zhu, X. Ronald; Sahoo, Narayan; Gillin, Michael T.

    2010-04-01

    In the region of high-dose gradients at the end of the proton range, the stopping power ratio of the protons undergoes significant changes, allowing for a broad spectrum of proton energies to be deposited within a relatively small volume. Because of the potential linear energy transfer dependence of LiF TLD-100 (thermolumescent dosimeter), dose measurements made in the distal fall-off region of a proton beam may be less accurate than those made in regions of low-dose gradients. The purpose of this study is to determine the accuracy and precision of dose measured using TLD-100 for a pristine Bragg peak, particularly in the distal fall-off region. All measurements were made along the central axis of an unmodulated 200-MeV proton beam from a Probeat passive beam-scattering proton accelerator (Hitachi, Ltd., Tokyo, Japan) at varying depths along the Bragg peak. Measurements were made using TLD-100 powder flat packs, placed in a virtual water slab phantom. The measurements were repeated using a parallel plate ionization chamber. The dose measurements using TLD-100 in a proton beam were accurate to within {+-}5.0% of the expected dose, previously seen in our past photon and electron measurements. The ionization chamber and the TLD relative dose measurements agreed well with each other. Absolute dose measurements using TLD agreed with ionization chamber measurements to within {+-} 3.0 cGy, for an exposure of 100 cGy. In our study, the differences in the dose measured by the ionization chamber and those measured by TLD-100 were minimal, indicating that the accuracy and precision of measurements made in the distal fall-off region of a pristine Bragg peak is within the expected range. Thus, the rapid change in stopping power ratios at the end of the range should not affect such measurements, and TLD-100 may be used with confidence as an in vivo dosimeter for proton beam therapy.

  17. Experimental results for an experimental condensation heat exchanger with a spiral minichanel tube. Comparison to numerical imulations

    NASA Astrophysics Data System (ADS)

    Peukert, P.; Hrubý, J.

    2013-04-01

    The paper describes new results for an experimental heat exchanger equipped with a single corrugated capillary tube, basic information about the measurements and the experimental setup. Some of the results were compared with numerical simulations.

  18. Can plumes collapse?: Experimental results and applications to Iceland.

    NASA Astrophysics Data System (ADS)

    Pears, M.; Lithgow-Bertelloni, C.

    2012-04-01

    Iceland has produced magma in a series of episodic events. From lava chemistry it has been inferred that the plume temperature decreased over the first 5 Myr by ~50°C and for the next 3 Myr following continental break up it continued to oscillate by ~25°C. Such data has been used to infer possible episodic collapse of the Iceland plume. Collapsing plumes are not common fluid dynamical features. In thermochemical plumes it is possible to achieve collapse by varying the relative buoyancy due to chemistry and due to temperature. In thermal plumes however, with a constant heat source we would expect plumes not to collapse but to not continue to rise after reaching a point of neutral buoyancy. We expect thermal plumes, like those Earth's bottom thermal boundary layer is capable of producing, to either rise to the surface or be deflected but not to collapse. We have designed an experimental setup to investigate the conditions that may lead to collapse in thermal plumes with constant heat sources. We used high-Prandtl number fluids with strongly temperature-dependent viscosities (Lyle Golden syrup and Liquidose 436) as analogues to Earth's high viscosity mantle in a cubic Plexiglas tank (26.5cm inner sides), heated by a circular 2cm diameter heater (flat with the base of the tank). We explored ΔTs between 3-60°C. The flow was visualized with shadowgraphs and an automated -3D Stereoscopic Particle Image Velocimetry (SPIV) system to measure velocities. In Lyle's Golden Syrup collapse occurred at ΔTs as high as 8°C, while in Liquidose 436 the 8°C ΔT run showed only partial collapse. The difference is not unexpected given the different physical properties. Partial collapse was seen even for ΔTs as high as 50°C. Both complete and partial collapse manifested themselves as downwelling flow in the central part of the conduit. Collapse stopped in the hotter plumes when the downwelling fluid met the hottest part of the conduit. The observed results suggest that diffusive

  19. Can plumes collapse?: Experimental results and applications to Iceland

    NASA Astrophysics Data System (ADS)

    Pears, M.; Lithgow-Bertelloni, C. R.

    2011-12-01

    Iceland has produced magma in a series of episodic events. From lava chemistry it has been inferred that the plume temperature decreased over the first 5 Myr by ~50°C and for the next 3 Myr following continental break up it continued to oscillate by ~25°C. Such data has been used to infer possible episodic collapse of the Iceland plume. Collapsing plumes are not common fluid dynamical features. In thermochemical plumes it is possible to achieve collapse by varying the relative buoyancy due to chemistry and due to temperature. In thermal plumes however, with a constant heat source we would expect plumes not to collapse but to not continue to rise after reaching a point of neutral buoyancy. We expect thermal plumes, like those Earth's bottom thermal boundary layer is capable of producing, to either rise to the surface or be deflected but not to collapse. We have designed an experimental setup to investigate the conditions that may lead to collapse in thermal plumes with constant heat sources. We used high-Prandtl number fluids with strongly temperature-dependent viscosities (Lyle Golden syrup and Liquidose 436) as analogues to Earth's high viscosity mantle in a cubic Plexiglas tank (26.5cm inner sides), heated by a circular 2cm diameter heater (flat with the base of the tank). We explored ΔTs between 3-60°C. The flow was visualized with shadowgraphs and an automated -3D Stereoscopic Particle Image Velocimetry (SPIV) system to measure velocities. In Lyle's Golden Syrup collapse occurred at ΔTs as high as 8°C, while in Liquidose 436 the 8° ΔT run showed only partial collapse. The difference is not unexpected given the different physical properties. Partial collapse was seen even for ΔTs as high as 50°C. Both complete and partial collapse manifested themselves as downwelling flow in the central part of the conduit. Collapse stopped in the hotter plumes when the downwelling fluid met the hottest part of the conduit. The observed results suggest that diffusive

  20. Automated detection of discourse segment and experimental types from the text of cancer pathway results sections.

    PubMed

    Burns, Gully A P C; Dasigi, Pradeep; de Waard, Anita; Hovy, Eduard H

    2016-01-01

    Automated machine-reading biocuration systems typically use sentence-by-sentence information extraction to construct meaning representations for use by curators. This does not directly reflect the typical discourse structure used by scientists to construct an argument from the experimental data available within a article, and is therefore less likely to correspond to representations typically used in biomedical informatics systems (let alone to the mental models that scientists have). In this study, we develop Natural Language Processing methods to locate, extract, and classify the individual passages of text from articles' Results sections that refer to experimental data. In our domain of interest (molecular biology studies of cancer signal transduction pathways), individual articles may contain as many as 30 small-scale individual experiments describing a variety of findings, upon which authors base their overall research conclusions. Our system automatically classifies discourse segments in these texts into seven categories (fact, hypothesis, problem, goal, method, result, implication) with an F-score of 0.68. These segments describe the essential building blocks of scientific discourse to (i) provide context for each experiment, (ii) report experimental details and (iii) explain the data's meaning in context. We evaluate our system on text passages from articles that were curated in molecular biology databases (the Pathway Logic Datum repository, the Molecular Interaction MINT and INTACT databases) linking individual experiments in articles to the type of assay used (coprecipitation, phosphorylation, translocation etc.). We use supervised machine learning techniques on text passages containing unambiguous references to experiments to obtain baseline F1 scores of 0.59 for MINT, 0.71 for INTACT and 0.63 for Pathway Logic. Although preliminary, these results support the notion that targeting information extraction methods to experimental results could provide

  1. Automated detection of discourse segment and experimental types from the text of cancer pathway results sections

    PubMed Central

    Burns, Gully A.P.C.; Dasigi, Pradeep; de Waard, Anita; Hovy, Eduard H.

    2016-01-01

    Automated machine-reading biocuration systems typically use sentence-by-sentence information extraction to construct meaning representations for use by curators. This does not directly reflect the typical discourse structure used by scientists to construct an argument from the experimental data available within a article, and is therefore less likely to correspond to representations typically used in biomedical informatics systems (let alone to the mental models that scientists have). In this study, we develop Natural Language Processing methods to locate, extract, and classify the individual passages of text from articles’ Results sections that refer to experimental data. In our domain of interest (molecular biology studies of cancer signal transduction pathways), individual articles may contain as many as 30 small-scale individual experiments describing a variety of findings, upon which authors base their overall research conclusions. Our system automatically classifies discourse segments in these texts into seven categories (fact, hypothesis, problem, goal, method, result, implication) with an F-score of 0.68. These segments describe the essential building blocks of scientific discourse to (i) provide context for each experiment, (ii) report experimental details and (iii) explain the data’s meaning in context. We evaluate our system on text passages from articles that were curated in molecular biology databases (the Pathway Logic Datum repository, the Molecular Interaction MINT and INTACT databases) linking individual experiments in articles to the type of assay used (coprecipitation, phosphorylation, translocation etc.). We use supervised machine learning techniques on text passages containing unambiguous references to experiments to obtain baseline F1 scores of 0.59 for MINT, 0.71 for INTACT and 0.63 for Pathway Logic. Although preliminary, these results support the notion that targeting information extraction methods to experimental results could provide

  2. Dynamic Strength of Peridotite at Seismic Slip Rates: Experimental Results

    NASA Astrophysics Data System (ADS)

    Del Gaudio, P.; di Toro, G.; Han, R.; Hirose, T.; Shimamoto, T.; Cocco, M.

    2006-12-01

    Ultramafic pseudotachylytes (solidified melts produced during seismic slip) decorate exhumed faults within the Balmuccia peridotite from the Ivrea zone (Italy). Unpublished studies suggest that these pseudotachylytes were produced in the upper-mantle/lower-crust. Kanamori et al. (1998) proposed extensive production of seismic melts during the Mw = 8.3 Bolivian 1994 deep focus (~600 km in depth) earthquake. It follows that seismic melting might occur in the mantle. We conducted high-velocity rock friction experiments with the Balmuccia peridotite to determine the dynamic strength of faults in the presence of ultramafic melts. During each experiment, shear stress evolved with displacement: after an initial peak shear stress, fault strength gradually decreased towards a steady-state value. Dynamic fault weakening was associated with the formation of a molten layer along the slipping zone. By performing experiments for increasing normal stresses (5 to 13 MPa) and slip rates (0.37÷1.14 m/s or ~seismic slip rates), steady-state shear stress (1) slightly increased with increasing normal stress and (2), for a given normal stress, decreased with increasing slip rate. The ratio between steady-state shear stress and normal stress was 0.13, well below the solid rock friction coefficient (~0.8). Experiments conducted under argon or fresh air flux yielded similar shear stress magnitudes, suggesting that olivine oxidation did not affect significantly the fault strength in the high-velocity experiments. The slight dependence of shear stress with normal stress suggests melt lubrication. Since the physics of melt lubrication is somehow predictable (see poster by Nielsen et al.), these experimental results might be extrapolated to the study of rupture dynamics in mantle rocks.

  3. Experimental subarachnoid haemorrhage results in multifocal axonal injury.

    PubMed

    Kummer, Terrance T; Magnoni, Sandra; MacDonald, Christine L; Dikranian, Krikor; Milner, Eric; Sorrell, James; Conte, Valeria; Benetatos, Joey J; Zipfel, Gregory J; Brody, David L

    2015-09-01

    The great majority of acute brain injury results from trauma or from disorders of the cerebrovasculature, i.e. ischaemic stroke or haemorrhage. These injuries are characterized by an initial insult that triggers a cascade of injurious cellular processes. The nature of these processes in spontaneous intracranial haemorrhage is poorly understood. Subarachnoid haemorrhage, a particularly deadly form of intracranial haemorrhage, shares key pathophysiological features with traumatic brain injury including exposure to a sudden pressure pulse. Here we provide evidence that axonal injury, a signature characteristic of traumatic brain injury, is also a prominent feature of experimental subarachnoid haemorrhage. Using histological markers of membrane disruption and cytoskeletal injury validated in analyses of traumatic brain injury, we show that axonal injury also occurs following subarachnoid haemorrhage in an animal model. Consistent with the higher prevalence of global as opposed to focal deficits after subarachnoid haemorrhage and traumatic brain injury in humans, axonal injury in this model is observed in a multifocal pattern not limited to the immediate vicinity of the ruptured artery. Ultrastructural analysis further reveals characteristic axonal membrane and cytoskeletal changes similar to those associated with traumatic axonal injury. Diffusion tensor imaging, a translational imaging technique previously validated in traumatic axonal injury, from these same specimens demonstrates decrements in anisotropy that correlate with histological axonal injury and functional outcomes. These radiological indicators identify a fibre orientation-dependent gradient of axonal injury consistent with a barotraumatic mechanism. Although traumatic and haemorrhagic acute brain injury are generally considered separately, these data suggest that a signature pathology of traumatic brain injury-axonal injury-is also a functionally significant feature of subarachnoid haemorrhage, raising

  4. Experimental subarachnoid haemorrhage results in multifocal axonal injury

    PubMed Central

    Magnoni, Sandra; MacDonald, Christine L.; Dikranian, Krikor; Milner, Eric; Sorrell, James; Conte, Valeria; Benetatos, Joey J.; Zipfel, Gregory J.; Brody, David L.

    2015-01-01

    The great majority of acute brain injury results from trauma or from disorders of the cerebrovasculature, i.e. ischaemic stroke or haemorrhage. These injuries are characterized by an initial insult that triggers a cascade of injurious cellular processes. The nature of these processes in spontaneous intracranial haemorrhage is poorly understood. Subarachnoid haemorrhage, a particularly deadly form of intracranial haemorrhage, shares key pathophysiological features with traumatic brain injury including exposure to a sudden pressure pulse. Here we provide evidence that axonal injury, a signature characteristic of traumatic brain injury, is also a prominent feature of experimental subarachnoid haemorrhage. Using histological markers of membrane disruption and cytoskeletal injury validated in analyses of traumatic brain injury, we show that axonal injury also occurs following subarachnoid haemorrhage in an animal model. Consistent with the higher prevalence of global as opposed to focal deficits after subarachnoid haemorrhage and traumatic brain injury in humans, axonal injury in this model is observed in a multifocal pattern not limited to the immediate vicinity of the ruptured artery. Ultrastructural analysis further reveals characteristic axonal membrane and cytoskeletal changes similar to those associated with traumatic axonal injury. Diffusion tensor imaging, a translational imaging technique previously validated in traumatic axonal injury, from these same specimens demonstrates decrements in anisotropy that correlate with histological axonal injury and functional outcomes. These radiological indicators identify a fibre orientation-dependent gradient of axonal injury consistent with a barotraumatic mechanism. Although traumatic and haemorrhagic acute brain injury are generally considered separately, these data suggest that a signature pathology of traumatic brain injury—axonal injury—is also a functionally significant feature of subarachnoid haemorrhage

  5. Experimental Results on Jets in pA

    NASA Astrophysics Data System (ADS)

    Appelt, Eric

    2015-04-01

    The experimentally observed reduction of jet yields in ultrarelativistic heavy ion (AA) collisions relative to proton-proton (pp) collisions is widely interpreted in terms of energy loss of a hard scattered parton traversing a quark-gluon plasma (QGP) before fragmenting into a jet of hadrons. In order to constrain proposed mechanisms of energy loss, a variety of measurements are needed that quantify both how the jet yields and jet structure are modified in the medium. However, jets may also be modified by differences in the initial state of the nucleus relative to that of the proton. The precise determination of the QGP properties relies on disentangling these additional modifications, collectively termed ``cold nuclear matter'' effects, from energy loss in the QGP. Collisions between heavy ions and protons (pA) provide a potential control environment where cold nuclear matter effects should be present, but QGP formation is generally not expected to occur. In this talk, an overview of recent jet results from proton-lead collisions produced at the LHC will be given. The yield of inclusive jets and distributions of dijet pairs are shown to be compatible with generally accepted theoretical expectations, although significant modification is observed when yields are measured from specific centrality classes of pA collision events. Some measurements of high-pT charged hadron yields suggest a larger modification in pA collisions relative to pp collisions than for inclusive jet yields. The potential implications of this difference along with other measurements relating to jet structure will be discussed.

  6. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    NASA Technical Reports Server (NTRS)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 C temperature increase from the nominal vapor temperature. The 19 C temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  7. Alkali Metal Backup Cooling for Stirling Systems - Experimental Results

    NASA Technical Reports Server (NTRS)

    Schwendeman, Carl; Tarau, Calin; Anderson, William G.; Cornell, Peggy A.

    2013-01-01

    In a Stirling Radioisotope Power System (RPS), heat must be continuously removed from the General Purpose Heat Source (GPHS) modules to maintain the modules and surrounding insulation at acceptable temperatures. The Stirling convertor normally provides this cooling. If the Stirling convertor stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS at the cost of an early termination of the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) can be used to passively allow multiple stops and restarts of the Stirling convertor. In a previous NASA SBIR Program, Advanced Cooling Technologies, Inc. (ACT) developed a series of sodium VCHPs as backup cooling systems for Stirling RPS. The operation of these VCHPs was demonstrated using Stirling heater head simulators and GPHS simulators. In the most recent effort, a sodium VCHP with a stainless steel envelope was designed, fabricated and tested at NASA Glenn Research Center (GRC) with a Stirling convertor for two concepts; one for the Advanced Stirling Radioisotope Generator (ASRG) back up cooling system and one for the Long-lived Venus Lander thermal management system. The VCHP is designed to activate and remove heat from the stopped convertor at a 19 degC temperature increase from the nominal vapor temperature. The 19 degC temperature increase from nominal is low enough to avoid risking standard ASRG operation and spoiling of the Multi-Layer Insulation (MLI). In addition, the same backup cooling system can be applied to the Stirling convertor used for the refrigeration system of the Long-lived Venus Lander. The VCHP will allow the refrigeration system to: 1) rest during transit at a lower temperature than nominal; 2) pre-cool the modules to an even lower temperature before the entry in Venus atmosphere; 3) work at nominal temperature on Venus surface; 4) briefly stop multiple times on the Venus surface to allow scientific measurements. This paper presents the experimental

  8. Autofocus imaging: Experimental results in an anisotropic austenitic weld

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Drinkwater, B. W.; Wilcox, P. D.; Hunter, A.

    2012-05-01

    The quality of an ultrasonic array image, especially for anisotropic material, depends on accurate information about acoustic properties. Inaccuracy of acoustic properties causes image degradation, e.g., blurring, errors in locating of reflectors and introduction of artifacts. In this paper, for an anisotropic austenitic steel weld, an autofocus imaging technique is presented. The array data from a series of beacons is captured and then used to statistically extract anisotropic weld properties by using a Monte-Carlo inversion approach. The beacon and imaging systems are realized using two separated arrays; one acts as a series of beacons and the other images these beacons. Key to the Monte-Carlo inversion scheme is a fast forward model of wave propagation in the anisotropic weld and this is based on the Dijkstra algorithm. Using this autofocus approach a measured weld map was extracted from an austenitic weld and used to reduce location errors, initially greater than 6mm, to less than 1mm.

  9. First accurate experimental study of Mu reactivity from a state-selected reactant in the gas phase: the Mu + H2{1} reaction rate at 300 K

    NASA Astrophysics Data System (ADS)

    Bakule, Pavel; Sukhorukov, Oleksandr; Ishida, Katsuhiko; Pratt, Francis; Fleming, Donald; Momose, Takamasa; Matsuda, Yasuyuki; Torikai, Eiko

    2015-02-01

    This paper reports on the experimental background and methodology leading to recent results on the first accurate measurement of the reaction rate of the muonium (Mu) atom from a state-selected reactant in the gas phase: the Mu + H2\\{1\\}\\to MuH + H reaction at 300 K, and its comparison with rigorous quantum rate theory, Bakule et al (2012 J. Phys. Chem. Lett. 3 2755). Stimulated Raman pumping, induced by 532 nm light from the 2nd harmonic of a Nd:YAG laser, was used to produce H2 in its first vibrational (v = 1) state, H2\\{1\\}, in a single Raman/reaction cell. A pulsed muon beam (from ‘ISIS’, at 50 Hz) matched the 25 Hz repetition rate of the laser, allowing data taking in equal ‘Laser-On/Laser-Off’ modes of operation. The signal to noise was improved by over an order of magnitude in comparison with an earlier proof-of-principle experiment. The success of the present experiment also relied on optimizing the overlap of the laser profile with the extended stopping distribution of the muon beam at 50 bar H2 pressure, in which Monte Carlo simulations played a central role. The rate constant, found from the analysis of three separate measurements, which includes a correction for the loss of {{H}2}\\{1\\} concentration due to collisional relaxation with unpumped H2 during the time of each measurement, is {{k}Mu}\\{1\\} = 9.9[(-1.4)(+1.7)] × 10-13 cm3 s-1 at 300 K. This is in good to excellent agreement with rigorous quantum rate calculations on the complete configuration interaction/Born-Huang surface, as reported earlier by Bakule et al, and which are also briefly commented on herein.

  10. A novel, integrated PET-guided MRS technique resulting in more accurate initial diagnosis of high-grade glioma.

    PubMed

    Kim, Ellen S; Satter, Martin; Reed, Marilyn; Fadell, Ronald; Kardan, Arash

    2016-06-01

    Glioblastoma multiforme (GBM) is the most common and lethal malignant glioma in adults. Currently, the modality of choice for diagnosing brain tumor is high-resolution magnetic resonance imaging (MRI) with contrast, which provides anatomic detail and localization. Studies have demonstrated, however, that MRI may have limited utility in delineating the full tumor extent precisely. Studies suggest that MR spectroscopy (MRS) can also be used to distinguish high-grade from low-grade gliomas. However, due to operator dependent variables and the heterogeneous nature of gliomas, the potential for error in diagnostic accuracy with MRS is a concern. Positron emission tomography (PET) imaging with (11)C-methionine (MET) and (18)F-fluorodeoxyglucose (FDG) has been shown to add additional information with respect to tumor grade, extent, and prognosis based on the premise of biochemical changes preceding anatomic changes. Combined PET/MRS is a technique that integrates information from PET in guiding the location for the most accurate metabolic characterization of a lesion via MRS. We describe a case of glioblastoma multiforme in which MRS was initially non-diagnostic for malignancy, but when MRS was repeated with PET guidance, demonstrated elevated choline/N-acetylaspartate (Cho/NAA) ratio in the right parietal mass consistent with a high-grade malignancy. Stereotactic biopsy, followed by PET image-guided resection, confirmed the diagnosis of grade IV GBM. To our knowledge, this is the first reported case of an integrated PET/MRS technique for the voxel placement of MRS. Our findings suggest that integrated PET/MRS may potentially improve diagnostic accuracy in high-grade gliomas. PMID:27122050

  11. Experimental results from a reverse flow annual combustor

    NASA Astrophysics Data System (ADS)

    Joubert, F. M.; Hattingh, H. V.

    Computer-predicted temperature distributions in the wall liners of a combustion chamber were compared to the experimentally obtained values from combustion tests carried out in a small, full-scale reverse-flow annular combustor at sea level take-off conditionns. The largest discrepancies between the measured and predicted linear temperatures occured in the primary zone, with most of the predictions falling above the measured values, and with neither of the two computer programs satisfying the accuracy of 4 percent (of the experimental values) needed for making estimates on the life of a combustor. On the other hand, the correlation between the measured and predicted liner pressure drop was satisfactory. The validity and usefulnes of simple computer models as aids in the design of gas turbine combustion chambers are discussed.

  12. CP Violation in B Meson Decays: Experimental Results

    SciTech Connect

    Lanceri, Livio; /Trieste U. /INFN, Trieste

    2005-08-30

    CP violation is intimately connected with the puzzle of matter-antimatter asymmetry and baryogenesis. In the Standard Model of particle physics, the observed CP violation phenomena are accounted for by the Cabibbo-Kobayashi-Maskawa mechanism involving a phase in the quark mixing matrix. This paper is devoted to a review of the experimental status of CP violation in the decays of B mesons.

  13. Experimental Results for an Annular Aerospike with Differential Throttling

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph H.; McDaniels, David M.

    2005-01-01

    A) MSFC funded an internal study on Altitude Compensating Nozzles: 1) Develop an ACN design and performance prediction tool. 2) Design, build and test cold flow ACN nozzles. 3) An annular aerospike nozzle was designed and tested. 4) Incorporated differential throttling to assess Thrust Vector Control. B) Objective of the test hardware: 1) Provide design tool verification. 2) Provide benchmark data for CFD calculations. 3) Experimentally measure side force, or TVC, for a differentially throttled annular aerospike.

  14. Z-scan theoretical and experimental studies for accurate measurements of the nonlinear refractive index and absorption of optical glasses near damage threshold

    NASA Astrophysics Data System (ADS)

    Olivier, Thomas; Billard, Franck; Akhouayri, Hassan

    2004-06-01

    Self-focusing is one of the dramatic phenomena that may occur during the propagation of a high power laser beam in a nonlinear material. This phenomenon leads to a degradation of the wave front and may also lead to a photoinduced damage of the material. Realistic simulations of the propagation of high power laser beams require an accurate knowledge of the nonlinear refractive index γ. In the particular case of fused silica and in the nanosecond regime, it seems that electronic mechanisms as well as electrostriction and thermal effects can lead to a significant refractive index variation. Compared to the different methods used to measure this parmeter, the Z-scan method is simple, offers a good sensitivity and may give absolute measurements if the incident beam is accurately studied. However, this method requires a very good knowledge of the incident beam and of its propagation inside a nonlinear sample. We used a split-step propagation algorithm to simlate Z-scan curves for arbitrary beam shape, sample thickness and nonlinear phase shift. According to our simulations and a rigorous analysis of the Z-scan measured signal, it appears that some abusive approximations lead to very important errors. Thus, by reducing possible errors on the interpretation of Z-scan experimental studies, we performed accurate measurements of the nonlinear refractive index of fused silica that show the significant contribution of nanosecond mechanisms.

  15. Additional correction for energy transfer efficiency calculation in filter-based Förster resonance energy transfer microscopy for more accurate results

    NASA Astrophysics Data System (ADS)

    Sun, Yuansheng; Periasamy, Ammasi

    2010-03-01

    Förster resonance energy transfer (FRET) microscopy is commonly used to monitor protein interactions with filter-based imaging systems, which require spectral bleedthrough (or cross talk) correction to accurately measure energy transfer efficiency (E). The double-label (donor+acceptor) specimen is excited with the donor wavelength, the acceptor emission provided the uncorrected FRET signal and the donor emission (the donor channel) represents the quenched donor (qD), the basis for the E calculation. Our results indicate this is not the most accurate determination of the quenched donor signal as it fails to consider the donor spectral bleedthrough (DSBT) signals in the qD for the E calculation, which our new model addresses, leading to a more accurate E result. This refinement improves E comparisons made with lifetime and spectral FRET imaging microscopy as shown here using several genetic (FRET standard) constructs, where cerulean and venus fluorescent proteins are tethered by different amino acid linkers.

  16. Optimal active vibration absorber - Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1993-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  17. Experimental overview of Generalized Parton Distribution results from HERMES

    SciTech Connect

    Zihlmann, B.

    2009-08-04

    Over the course of more than a decade the HERMES experiment has accumulated a wealth of data with electron and positron beams on various gaseous targets from Hydrogen up to Xenon. In addition, the beams and targets can be polarized. This data set is viewed in the context of Generalized Parton Distributions, a theoretical formalism with an explicit three dimensional view of the structure of the nucleon. It provides a link between experimental observables and the total angular momentum of the quarks in the nucleon.

  18. RFI in hybrid loops - Simulation and experimental results.

    NASA Technical Reports Server (NTRS)

    Ziemer, R. E.; Nelson, D. R.; Raghavan, H. R.

    1972-01-01

    A digital simulation of an imperfect second-order hybrid phase-locked loop (HPLL) operating in radio frequency interference (RFI) is described. Its performance is characterized in terms of phase error variance and phase error probability density function (PDF). Monte-Carlo simulation is used to show that the HPLL can be superior to the conventional phase-locked loops in RFI backgrounds when minimum phase error variance is the goodness criterion. Similar experimentally obtained data are given in support of the simulation data.

  19. Experimental Studies of Ion Beam Neutralization: Preliminary Results

    SciTech Connect

    Ding, N.; Polansky, J.; Downey, R.; Wang, J.

    2011-05-20

    A testing platform is designed to study ion beam neutralization in the mesothermal, collisionless region. In the experimental setup, argon neutrals were ionized in a microwave cavity and accelerated by a plasma lens system which was biased to 2500 V above the system ground. Electrons were boiled off from two hot tungsten filaments to neutralize the ion beam. The plasma is diagnosed using Langmuir probe and Faraday probe. A 3-D traversing system and a complete data acquisition loop were developed to efficiently measure 3-D beam profile. Preliminary measurements of beam profiles are presented for different operating conditions.

  20. Optimal active vibration absorber: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Lee-Glauser, Gina; Juang, Jer-Nan; Sulla, Jeffrey L.

    1992-01-01

    An optimal active vibration absorber can provide guaranteed closed-loop stability and control for large flexible space structures with collocated sensors/actuators. The active vibration absorber is a second-order dynamic system which is designed to suppress any unwanted structural vibration. This can be designed with minimum knowledge of the controlled system. Two methods for optimizing the active vibration absorber parameters are illustrated: minimum resonant amplitude and frequency matched active controllers. The Controls-Structures Interaction Phase-1 Evolutionary Model at NASA LaRC is used to demonstrate the effectiveness of the active vibration absorber for vibration suppression. Performance is compared numerically and experimentally using acceleration feedback.

  1. Comparison of thermal modeling and experimental results of a generic model for ground vehicle

    NASA Astrophysics Data System (ADS)

    Bushlin, Y.; Lessin, A.; Reinov, A.

    2006-05-01

    Accurate thermal modeling requires verification and validation of the model and software being used. For basic evaluation of thermal prediction models and software tools, a generic model - CUBI was build. The model was designed to have simple geometry yet, consisted of similar characteristics as of a ground vehicle. The model was equipped with thermocouples for measuring its temperature variations and was placed in a typical desert environment for field testing. The experimental setup also included a meteorological station. The data collected was used for the thermal behavior analysis of the generic model and for comparison with the thermal calculations predictions. Comparison of the results shows sufficient compliance but yet reviles some issues in the modeling that should be addressed.

  2. Fault induction dynamic model, suitable for computer simulation: Simulation results and experimental validation

    NASA Astrophysics Data System (ADS)

    Baccarini, Lane Maria Rabelo; de Menezes, Benjamim Rodrigues; Caminhas, Walmir Matos

    2010-01-01

    The study of induction motor behavior under not normal conditions and the ability to detect and predict these conditions has been an area of increasing interest. Early detection and diagnosis of incipient faults are desirable for interactive evaluation over the running condition, product quality guarantee, and improved operational efficiency of induction motors. The main difficulty in this task is the lack of accurate analytical models to describe a faulty motor. This paper proposes a dynamic model to analyze electrical and mechanical faults in induction machines and includes net asymmetries and load conditions. The model permits to analyze the interactions between different faults in order to detect possible false alarms. Simulations and experimental results were performed to confirm the validity of the model.

  3. Titanium as reactor material for SCWO applications. First experimental results

    SciTech Connect

    Boukis, N.; Friedrich, C.; Dinjus, E.

    1998-12-31

    According to literature data, nickel base alloys are not sufficiently corrosion resistant in chloride bearing SCWO environments. Titanium was proposed several times as a suitable material for the construction of a corrosion resistant reactor. Titanium does not show the required mechanical strength for high temperature high pressure applications and it can only be used to form liners for an SCWO apparatus. Therefore, pressure tubes made of alloy 625 were lined with titanium grade 2. Additionally corrosion tests with coupons made of titanium grades 2, 5, 7, 12 and {beta}-C were performed. The coupons were placed inside an alumina-lined reactor. Materials were exposed to simulated SCWO feeds consisting of water, oxygen and HCl, H{sub 2}SO{sub 4}, or H{sub 3}PO{sub 4}. Experimental temperatures were up to 600 C, pressures up to 27 MPa and experimental times up to 200 hours. Corrosion in chloride containing solution is low. In the presence of sulfate or phosphate, corrosion of titanium grade 2 becomes severe. For these environments an upper limit of the corrosion rate could be estimated.

  4. CSI Flight Computer System and experimental test results

    NASA Technical Reports Server (NTRS)

    Sparks, Dean W., Jr.; Peri, F., Jr.; Schuler, P.

    1993-01-01

    This paper describes the CSI Computer System (CCS) and the experimental tests performed to validate its functionality. This system is comprised of two major components: the space flight qualified Excitation and Damping Subsystem (EDS) which performs controls calculations; and the Remote Interface Unit (RIU) which is used for data acquisition, transmission, and filtering. The flight-like RIU is the interface between the EDS and the sensors and actuators positioned on the particular structure under control. The EDS and RIU communicate over the MIL-STD-1553B, a space flight qualified bus. To test the CCS under realistic conditions, it was connected to the Phase-0 CSI Evolutionary Model (CEM) at NASA Langley Research Center. The following schematic shows how the CCS is connected to the CEM. Various tests were performed which validated the ability of the system to perform control/structures experiments.

  5. Experimental results on spin physics at the AGS

    SciTech Connect

    Makdisi, Y.I.

    1986-01-01

    The AGS ran with polarized protons towards the end of 1985 and through the first two months of 1986. This comprised commissioning periods interleaved with two runs for physics at 13.5 GeV/c with beam polarization of 50 to 60%, and 18.5 GeV/c with an average beam polarization of 40%. Later, the AGS polarized beam reached peak energy of 22 GeV/c and polarization of 46%. This article describes the various spin related experimental efforts since the VI Symposium at Marseille. These will be grouped into those using unpolarized beams and the rest are the polarized proton beam users. Afterwards the future of the program is described as extensions of current experiments in addition to other measurements that are yet to be proposed.

  6. Experimental results for a microscale ethanol vapor jet ejector

    NASA Astrophysics Data System (ADS)

    Gardner, W. G.; Jaworski, J. W.; Camacho, A. P.; Protz, J. M.

    2010-04-01

    A microscale jet ejector driven by ethanol vapor is designed and tested to induce a suction draft using a supersonic converging-diverging micronozzle. A three-dimensional axisymmetric nozzle is fabricated using electro-discharge machining to produce a throat diameter of 187 µm with an expansion ratio of 3:1. The motive nozzle achieves a design mass flow efficiency of 93% compared to isentropic calculations. Two different ejector area ratios are compared using ethanol vapor and nitrogen gas separately to motivate and entrain ambient air. The experimental data indicate that the ejector can produce a sufficient suction draft to satisfy both microengine mass flow and power off-take requirements to enable its substitution for high-speed microscale pumping turbomachinery.

  7. Towards more accurate isoscapes encouraging results from wine, water and marijuana data/model and model/model comparisons.

    NASA Astrophysics Data System (ADS)

    West, J. B.; Ehleringer, J. R.; Cerling, T.

    2006-12-01

    Understanding how the biosphere responds to change it at the heart of biogeochemistry, ecology, and other Earth sciences. The dramatic increase in human population and technological capacity over the past 200 years or so has resulted in numerous, simultaneous changes to biosphere structure and function. This, then, has lead to increased urgency in the scientific community to try to understand how systems have already responded to these changes, and how they might do so in the future. Since all biospheric processes exhibit some patchiness or patterns over space, as well as time, we believe that understanding the dynamic interactions between natural systems and human technological manipulations can be improved if these systems are studied in an explicitly spatial context. We present here results of some of our efforts to model the spatial variation in the stable isotope ratios (δ2H and δ18O) of plants over large spatial extents, and how these spatial model predictions compare to spatially explicit data. Stable isotopes trace and record ecological processes and as such, if modeled correctly over Earth's surface allow us insights into changes in biosphere states and processes across spatial scales. The data-model comparisons show good agreement, in spite of the remaining uncertainties (e.g., plant source water isotopic composition). For example, inter-annual changes in climate are recorded in wine stable isotope ratios. Also, a much simpler model of leaf water enrichment driven with spatially continuous global rasters of precipitation and climate normals largely agrees with complex GCM modeling that includes leaf water δ18O. Our results suggest that modeling plant stable isotope ratios across large spatial extents may be done with reasonable accuracy, including over time. These spatial maps, or isoscapes, can now be utilized to help understand spatially distributed data, as well as to help guide future studies designed to understand ecological change across

  8. Construction of a WMR for Trajectory Tracking Control: Experimental Results

    PubMed Central

    Silva-Ortigoza, R.; Márquez-Sánchez, C.; Marcelino-Aranda, M.; Marciano-Melchor, M.; Silva-Ortigoza, G.; Bautista-Quintero, R.; Ramos-Silvestre, E. R.; Rivera-Díaz, J. C.; Muñoz-Carrillo, D.

    2013-01-01

    This paper reports a solution for trajectory tracking control of a differential drive wheeled mobile robot (WMR) based on a hierarchical approach. The general design and construction of the WMR are described. The hierarchical controller proposed has two components: a high-level control and a low-level control. The high-level control law is based on an input-output linearization scheme for the robot kinematic model, which provides the desired angular velocity profiles that the WMR has to track in order to achieve the desired position (x∗, y∗) and orientation (φ∗). Then, a low-level control law, based on a proportional integral (PI) approach, is designed to control the velocity of the WMR wheels to ensure those tracking features. Regarding the trajectories, this paper provides the solution or the following cases: (1) time-varying parametric trajectories such as straight lines and parabolas and (2) smooth curves fitted by cubic splines which are generated by the desired data points {(x1∗, y1∗),..., (xn∗, yn∗)}. A straightforward algorithm is developed for constructing the cubic splines. Finally, this paper includes an experimental validation of the proposed technique by employing a DS1104 dSPACE electronic board along with MATLAB/Simulink software. PMID:23997679

  9. EXPERIMENTAL RESULTS FROM A MICROWAVE CAVITY BEAM POSITION MONITOR.

    SciTech Connect

    BALAKIN,V.; BAZHAN,A.; LUNEV,P.; SOLYAK,N.; VOGEL,V.; ZHOGOLEV,P.; LISITSYN,A.; YAKIMENKO,V.

    1999-03-29

    Future Linear Colliders have hard requirements for the beam transverse position stability in the accelerator. A beam Position Monitor (BPM) with the resolution better than 0.1 micron in the single bunch regime is needed to control the stability of the beam position along the linac. Proposed BPM is based on the measurement of the asymmetrical mode excited by single bunch in the cavity. Four stages of signal processing (space-, time-, frequency- and phase-filtering providing the required signal-to-noise ratio) are used to obtain extremely high resolution. The measurement set-up was designed by BINP and installed at ATF/BNL to test experimentally this concept. The set-up includes three two-coordinates BPM's at the frequency of 13.566 GHz, and reference intensity/phase cavity. BPM's were mounted on support table. The two-coordinates movers allow to move and align BPM's along the straight line, using the signals from the beam. The position of each monitor is controlled by the sensors with the accuracy 0.03 micron. The information from three monitors allows to exclude angle and position jitter of the beam and measure BPM resolution. In the experiments the resolution of about 0.15 micron for 0.25 nC beam intensity was obtained, that is close to the value required.

  10. Modeling of rock friction 1. Experimental results and constitutive equations

    USGS Publications Warehouse

    Dieterich, J.H.

    1979-01-01

    Direct shear experiments on ground surfaces of a granodiorite from Raymond, California, at normal stresses of ??6 MPa demonstrate that competing time, displacement, and velocity effects control rock friction. It is proposed that the strength of the population of points of contacts between sliding surfaces determines frictional strength and that the population of contacts changes continuously with displacements. Previous experiments demonstrate that the strength of the contacts increases with the age of the contacts. The present experiments establish that a characteristic displacement, proportional to surface roughness, is required to change the population of contacts. Hence during slip the average age of the points of contact and therefore frictional strength decrease as slip velocity increases. Displacement weakening and consequently the potential for unstable slip occur whenever displacement reduces the average age of the contacts. In addition to this velocity dependency, which arises from displacement dependency and time dependency, the experiments also show a competing but transient increase in friction whenever slip velocity increases. Creep of the sliding surface at stresses below that for steady state slip is also observed. Constitutive relationships are developed that permit quantitative simulation of the friction versus displacement data as a function of surface roughness and for different time and velocity histories. Unstable slip in experiments is controlled by these constitutive effects and by the stiffness of the experimental system. It is argued that analogous properties control earthquake instability. Copyright ?? 1979 by the American Geophysical Union.

  11. Construction of a WMR for trajectory tracking control: experimental results.

    PubMed

    Silva-Ortigoza, R; Márquez-Sánchez, C; Marcelino-Aranda, M; Marciano-Melchor, M; Silva-Ortigoza, G; Bautista-Quintero, R; Ramos-Silvestre, E R; Rivera-Díaz, J C; Muñoz-Carrillo, D

    2013-01-01

    This paper reports a solution for trajectory tracking control of a differential drive wheeled mobile robot (WMR) based on a hierarchical approach. The general design and construction of the WMR are described. The hierarchical controller proposed has two components: a high-level control and a low-level control. The high-level control law is based on an input-output linearization scheme for the robot kinematic model, which provides the desired angular velocity profiles that the WMR has to track in order to achieve the desired position (x∗, y∗) and orientation (φ∗). Then, a low-level control law, based on a proportional integral (PI) approach, is designed to control the velocity of the WMR wheels to ensure those tracking features. Regarding the trajectories, this paper provides the solution or the following cases: (1) time-varying parametric trajectories such as straight lines and parabolas and (2) smooth curves fitted by cubic splines which are generated by the desired data points {(x₁∗, y₁∗),..., (x(n)∗, y(n)∗)}. A straightforward algorithm is developed for constructing the cubic splines. Finally, this paper includes an experimental validation of the proposed technique by employing a DS1104 dSPACE electronic board along with MATLAB/Simulink software. PMID:23997679

  12. Experimental results with hydrogen fueled internal combustion engines

    NASA Technical Reports Server (NTRS)

    De Boer, P. C. T.; Mclean, W. J.; Homan, H. S.

    1975-01-01

    The paper focuses on the most important experimental findings for hydrogen-fueled internal combustion engines, with particular reference to the application of these findings to the assessment of the potential of hydrogen engines. Emphasis is on the various tradeoffs that can be made, such as between maximum efficiency, maximum power, and minimum NO emissions. The various possibilities for induction and ignition are described. Some projections are made about areas in which hydrogen engines may find their initial application and about optimum ways to design such engines. It is shown that hydrogen-fueled reciprocal internal combustion engines offer important advantages with respect to thermal efficiency and exhaust emissions. Problems arising from preignition can suitably be avoided by restricting the fuel-air equivalence ratio to values below about 0.5. The direct cylinder injection appears to be a very attractive way to operate the engine, because it combines a wide range of possible power outputs with a high thermal efficiency and very low NO emissions at part loads.

  13. Transport of fluorobenzoate tracers in a vegetated hydrologic control volume: 1. Experimental results

    NASA Astrophysics Data System (ADS)

    Queloz, Pierre; Bertuzzo, Enrico; Carraro, Luca; Botter, Gianluca; Miglietta, Franco; Rao, P. S. C.; Rinaldo, Andrea

    2015-04-01

    This paper reports about the experimental evidence collected on the transport of five fluorobenzoate tracers injected under controlled conditions in a vegetated hydrologic volume, a large lysimeter (fitted with load cells, sampling ports, and an underground chamber) where two willows prompting large evapotranspiration fluxes had been grown. The relevance of the study lies in the direct and indirect measures of the ways in which hydrologic fluxes, in this case, evapotranspiration from the upper surface and discharge from the bottom drainage, sample water and solutes in storage at different times under variable hydrologic forcings. Methods involve the accurate control of hydrologic inputs and outputs and a large number of suitable chemical analyses of water samples in discharge waters. Mass extraction from biomass has also been performed ex post. The results of the 2 year long experiment established that our initial premises on the tracers' behavior, known to be sorption-free under saturated conditions which we verified in column leaching tests, were unsuitable as large differences in mass recovery appeared. Issues on reactivity thus arose and were addressed in the paper, in this case attributed to microbial degradation and solute plant uptake. Our results suggest previously unknown features of fluorobenzoate compounds as hydrologic tracers, potentially interesting for catchment studies owing to their suitability for distinguishable multiple injections, and an outlook on direct experimental closures of mass balance in hydrologic transport volumes involving fluxes that are likely to sample differently stored water and solutes.

  14. Assessment of a sponge layer as a non-reflective boundary treatment with highly accurate gust–airfoil interaction results

    NASA Astrophysics Data System (ADS)

    Crivellini, A.

    2016-02-01

    This paper deals with the numerical performance of a sponge layer as a non-reflective boundary condition. This technique is well known and widely adopted, but only recently have the reasons for a sponge failure been recognised, in analysis by Mani. For multidimensional problems, the ineffectiveness of the method is due to the self-reflections of the sponge occurring when it interacts with an oblique acoustic wave. Based on his theoretical investigations, Mani gives some useful guidelines for implementing effective sponge layers. However, in our opinion, some practical indications are still missing from the current literature. Here, an extensive numerical study of the performance of this technique is presented. Moreover, we analyse a reduced sponge implementation characterised by undamped partial differential equations for the velocity components. The main aim of this paper relies on the determination of the minimal width of the layer, as well as of the corresponding strength, required to obtain a reflection error of no more than a few per cent of that observed when solving the same problem on the same grid, but without employing the sponge layer term. For this purpose, a test case of computational aeroacoustics, the single airfoil gust response problem, has been addressed in several configurations. As a direct consequence of our investigation, we present a well documented and highly validated reference solution for the far-field acoustic intensity, a result that is not well established in the literature. Lastly, the proof of the accuracy of an algorithm for coupling sub-domains solved by the linear and non-liner Euler governing equations is given. This result is here exploited to adopt a linear-based sponge layer even in a non-linear computation.

  15. Experimental test results of a generalized parameter fuel control

    NASA Technical Reports Server (NTRS)

    Batterton, P. G.; Gold, H.

    1973-01-01

    Considerable interest has been generated recently in low cost jet propulsion systems. One of the more complicated components of jet engines is the fuel control. Results of an effort to develop a simpler hydromechanical fuel control are presented. This prototype fuel control was installed on a J85-GE-13 jet engine. Results show that the fuel control provided satisfactory engine performance at sea level static conditions over its normal nonafterburning operating range, including startup. Results of both bench and engine tests are presented; the difficulties encountered are described.

  16. The route to MBxNyCz molecular wheels: II. Results using accurate functionals and basis sets

    NASA Astrophysics Data System (ADS)

    Güthler, A.; Mukhopadhyay, S.; Pandey, R.; Boustani, I.

    2014-04-01

    Applying ab initio quantum chemical methods, molecular wheels composed of metal and light atoms were investigated. High quality basis sets 6-31G*, TZPV, and cc-pVTZ as well as exchange and non-local correlation functionals B3LYP, BP86 and B3P86 were used. The ground-state energy and structures of cyclic planar and pyramidal clusters TiBn (for n = 3-10) were computed. In addition, the relative stability and electronic structures of molecular wheels TiBxNyCz (for x, y, z = 0-10) and MBnC10-n (for n = 2 to 5 and M = Sc to Zn) were determined. This paper sustains a follow-up study to the previous one of Boustani and Pandey [Solid State Sci. 14 (2012) 1591], in which the calculations were carried out at the HF-SCF/STO3G/6-31G level of theory to determine the initial stability and properties. The results show that there is a competition between the 2D planar and the 3D pyramidal TiBn clusters (for n = 3-8). Different isomers of TiB10 clusters were also studied and a structural transition of 3D-isomer into 2D-wheel is presented. Substitution boron in TiB10 by carbon or/and nitrogen atoms enhances the stability and leads toward the most stable wheel TiB3C7. Furthermore, the computations show that Sc, Ti and V at the center of the molecular wheels are energetically favored over other transition metal atoms of the first row.

  17. Primary simulation and experimental results of a coaxial plasma accelerator

    NASA Astrophysics Data System (ADS)

    Chen, Z.; Huang, J.; Han, J.; Zhang, Z.; Quan, R.; Wang, L.; Yang, X.; Feng, C.

    A coaxial plasma accelerator with a compressing coil is developed to simulate the impacting and erosion effect of space debris on exposed materials of spacecrafts During its adjustment operation some measurements are conducted including discharging current by Rogowski coil average plasma speed in the coaxial gun by magnetic coils and ejected particle speed by piezoelectric sensor etc In concert with the experiment a primary physical model is constructed in which only the coaxial gun is taken into account with the compressor coil not considered for its unimportant contribution to the plasma ejection speed The calculation results by the model agree well with the diagnostic results considering some assumptions for simplification Based on the simulation result some important suggestions for optimum design and adjustment of the accelerator are obtained for its later operation

  18. Railgun hybrid armatures, experimental results and performance characteristics

    NASA Astrophysics Data System (ADS)

    Crawford, Roger; Keefer, Dennis; Sedghinasab, Ahad

    1991-01-01

    Six hybrid armature designs were evaluated in the UTSI one-centimeter square-bore railgun. Advanced diagnostic instrumentation was used to determine the characteristics of hybrid armatures which include a compound armature (current in plasma brushes to the metal armature followed by a plasma armature). The hybrid armatures were compact, with shorter current distributions than plasma armatures as measured with both optical and electromagnetic probes. Although the results are preliminary, due to the limited geometries investigated, the results are very encouraging. The short (less than one-bore-diameter) hybrids demonstrated efficiencies equal to or greater than plasma armatures and good armature stability.

  19. Pegasus liner stability experiments: Diagnostics and experimental results

    SciTech Connect

    Clark, D.A.; Morgan, D.V.; Rodriguez, G.

    1998-12-31

    A series of experiments to compare imploding cylindrical liner performance with Magneto-HydroDynamic (MHD) modeling has been performed at the Los Alamos National Laboratory Pegasus capacitor bank. Several configurations of aluminum liners have been used; some with initial perturbations and some smooth. Instability growth resulting from the perturbations has been observed with high resolution. Load diagnostics included radial x-rays, fiber optic impact pins, and VISAR (Velocity Interferometer for a Surface of Any Reflector). Diagnostic results and comparisons for several liner stability (LS) experiments are presented.

  20. Qualitative versus Quantitative Results: An Experimental Introduction to Data Interpretation.

    ERIC Educational Resources Information Center

    Johnson, Eric R.; Alter, Paula

    1989-01-01

    Described is an experiment in which the student can ascertain the meaning of a negative result from a qualitative test by performing a more sensitive quantitative test on the same sample. Methodology for testing urinary glucose with a spectrophotometer at 630 nm and with commercial assaying glucose strips is presented. (MVL)

  1. Comments on experimental results of energy confinement of tokamak plasmas

    SciTech Connect

    Chu, T.K.

    1989-04-01

    The results of energy-confinement experiments on steady-state tokamak plasmas are examined. For plasmas with auxiliary heating, an analysis based on the heat diffusion equation is used to define heat confinement time (the incremental energy confinement time). For ohmically sustained plasmas, experiments show that the onset of the saturation regime of energy confinement, marfeing, detachment, and disruption are marked by distinct values of the parameter /bar n//sub e///bar j/. The confinement results of the two types of experiments can be described by a single surface in 3-dimensional space spanned by the plasma energy, the heating power, and the plasma density: the incremental energy confinement time /tau//sub inc/ = ..delta..W/..delta..P is the correct concept for describing results of heat confinement in a heating experiment; the commonly used energy confinement time defined by /tau//sub E/ = W/P is not. A further examination shows that the change of edge parameters, as characterized by the change of the effective collision frequency ..nu../sub e/*, governs the change of confinement properties. The totality of the results of tokamak experiments on energy confinement appears to support a hypothesis that energy transport is determined by the preservation of the pressure gradient scale length. 70 refs., 6 figs., 1 tab.

  2. Joint Soviet-American experiment on hypokinesia: Experimental results

    NASA Technical Reports Server (NTRS)

    Burovskiy, N. N.

    1979-01-01

    Comprehensive results are reported from the Soviet portion of a joint Soviet-American experiment involving hypokinesia. The main emphases are on chemical analyses of blood and urine, functional tests, and examination of the cardiovascular system by electrocardiography, echocardiography, and plethysmography.

  3. New experimental methodology, setup and LabView program for accurate absolute thermoelectric power and electrical resistivity measurements between 25 and 1600 K: Application to pure copper, platinum, tungsten, and nickel at very high temperatures

    SciTech Connect

    Abadlia, L.; Mayoufi, M.; Gasser, F.; Khalouk, K.; Gasser, J. G.

    2014-09-15

    In this paper we describe an experimental setup designed to measure simultaneously and very accurately the resistivity and the absolute thermoelectric power, also called absolute thermopower or absolute Seebeck coefficient, of solid and liquid conductors/semiconductors over a wide range of temperatures (room temperature to 1600 K in present work). A careful analysis of the existing experimental data allowed us to extend the absolute thermoelectric power scale of platinum to the range 0-1800 K with two new polynomial expressions. The experimental device is controlled by a LabView program. A detailed description of the accurate dynamic measurement methodology is given in this paper. We measure the absolute thermoelectric power and the electrical resistivity and deduce with a good accuracy the thermal conductivity using the relations between the three electronic transport coefficients, going beyond the classical Wiedemann-Franz law. We use this experimental setup and methodology to give new very accurate results for pure copper, platinum, and nickel especially at very high temperatures. But resistivity and absolute thermopower measurement can be more than an objective in itself. Resistivity characterizes the bulk of a material while absolute thermoelectric power characterizes the material at the point where the electrical contact is established with a couple of metallic elements (forming a thermocouple). In a forthcoming paper we will show that the measurement of resistivity and absolute thermoelectric power characterizes advantageously the (change of) phase, probably as well as DSC (if not better), since the change of phases can be easily followed during several hours/days at constant temperature.

  4. Recent Experimental Results from Cryogenic Implosions on OMEGA

    NASA Astrophysics Data System (ADS)

    Sangster, T. C.; Goncharov, V. N.; Radha, P. B.; Betti, R.; Boehly, T. R.; Glebov, V. Yu.; Hu, S. X.; McCrory, R. L.; McKenty, P. W.; Meyerhofer, D. D.; Seka, W.; Smalyuk, V. A.; Frenje, J. A.; Petrasso, R. D.; Shvarts, D.

    2008-11-01

    The implosion performance of energy-scaled cryogenic D2 and DT targets on the 60-beam OMEGA laser is important for understanding the physics of highly compressed fuel and the validation of ignition designs for the NIF. Recent experiments have demonstrated good performance using a multi-shock drive that has been tuned based on cryogenic cone-in-shell targets. Fuel areal densities are now consistently exceeding 80% of the 1-D prediction, while the yields are between 10% and 20% of 1-D predictions. These results demonstrate the benefit (and necessity) of an independent shock-timing platform. This talk will present the latest implosion performance results and potentially show the first cryogenic-fuel-core radiographs using a short pulse beam from the new OMEGA EP Laser Facility. This work was supported by the U.S. Department of Energy Office of Inertial Confinement Fusion under Cooperative Agreement No. DE-FC52-08NA28302.

  5. The behavior of delaminations in composite materials - experimental results

    NASA Astrophysics Data System (ADS)

    Chermoshentseva, A. S.; Pokrovskiy, A. M.; Bokhoeva, L. A.

    2016-02-01

    Delamination is one of the most common failure modes of composite materials. It may occur as a consequence of imperfections in the production process or the effects of external factors during the operational life of the composite laminates, such as the impact by foreign objects. This paper presents the results of mechanical tests and the optimum degrees of filling the composite materials (CM) with hydrophobic powder (Tarkosil T-20) depending on the latter mass concentration. The results present test samples of the CM with the underlying interlayer defects. The samples were fabricated of twenty-ply pre-preg (fiberglass or carbon fiber). The industrial grade glass is T-25 (VM) specification 6-11-380-76. The composite materials have nanosized additives in structure. The volume concentration of nanopowders is varying from 0.1% to 0.5%. This kind of research has been done for the first time.

  6. Delaminations in composite plates under transverse static loads - Experimental results

    NASA Technical Reports Server (NTRS)

    Finn, Scott R.; He, Yi-Fei; Springer, George S.

    1992-01-01

    Tests were performed measuring the damage initiation loads and the locations, shapes, and sizes of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite-PEEK plates subjected to transverse static loads. The data were compared to the results of the Finn-Springer model, and good agreements were found between the measured and calculated delamination lengths and widths.

  7. Fate and Transport of Graphene Oxide in Granular Porous Media: Experimental Results and Modeling

    NASA Astrophysics Data System (ADS)

    Gao, Bin

    2014-05-01

    Although graphene oxide (GO) has been used in many applications to improve human life quality, its environmental fate and behavior are still largely unknown. In this work, a range of laboratory experiments were conducted to explore the aggregation, deposition, and transport mechanisms of GO nano-sheets in porous media under various conditions. Stability experimental data showed that both cation valence and pH showed significant effect on the aggregation of GO sheets. The measured critical coagulation concentrations were in good agreement with the predictions of the extended Schulze-Hardy rule. Sand column experimental results indicated that deposition and transport of GO in porous media were strongly dependent on solution ionic strength. Particularly, GO showed high mobility under low ionic strength conditions in both saturated and unsaturated columns. Increasing ionic strength dramatically increased the retention of GO in porous media, mainly through secondary-minimum deposition. Recovery rates of GO in unsaturated sand columns were lower than that in saturated columns under the same ionic strength conditions, suggesting moisture content also played an important role in the retention of GO in porous media. Findings from the bubble column experiments showed that the GO did not attach to the air-water interface, which is consistent with the XDLVO predictions. Additional retention mechanisms, such as film straining, thus could be responsible to the reduced mobility of GO in unsaturated porous media. The breakthrough curves of GO in saturated and unsaturated columns could be accurately simulated by an advection-dispersion-reaction model.

  8. Structural and vibrational study of graphene oxide via coronene based models: theoretical and experimental results

    NASA Astrophysics Data System (ADS)

    Almeida de Mendonça, João Paulo; Henrique de Lima, Alessandro; Amaral Junqueira, Georgia Maria; Gianini Quirino, Welber; Legnani, Cristiano; Oliveira Maciel, Indhira; Sato, Fernando

    2016-05-01

    We use the Coronene (C24H12), a simple and finite molecule, to make a model to study the spectroscopic and structural alterations generated by oxygenated groups in graphene oxide (GO). Based on the Lerf–Klinowski model, we chose the hydroxyl [OH‑], the carboxyl [COOH‑] and the epoxy [the ring C2O inside the molecule] as our radicals of interest and study their collective and isolated effects. We perform geometry optimization, vibrational IR (via AM1 and DFT-B3LYP) and Raman spectra (via DFT-B3LYP) of a series of functionalized coronene molecules. As results, we obtain some useful data for the analysis of IR and Raman spectra of GO, which facilitate the understanding and identification of the peaks found in the experiment. Finally, we suggest a new model to study GO, producing an accurate signature when compared to our experimental data. Such molecule shows in more details of the structural effects caused by functionalization when compared to experimental data.

  9. Experimental results on the atmospheric muon charge ratio

    NASA Astrophysics Data System (ADS)

    Mauri, N.

    2016-07-01

    The atmospheric muon charge ratio, defined as the number of positive over negative charged muons, is a highly informative observable both for cosmic rays and particle physics. It allows studying the features of high-energy hadronic interactions in the forward region and the composition of primary cosmic rays. In this review results from underground experiments measuring the charge ratio around 1 TeV are discussed. The measurements in the TeV energy region constrain the associated kaon production, which is particularly important e.g. for the calculation of the atmospheric neutrino flux.

  10. Delaminations in composite plates under transverse impact loads - Experimental results

    NASA Technical Reports Server (NTRS)

    Finn, Scott R.; He, Ye-Fei; Springer, George S.

    1993-01-01

    Tests were performed measuring the locations and geometries of delaminations in Fiberite T300/976 graphite/epoxy, Fiberite IM7/977-2 graphite-toughened epoxy, and ICI APC-2 graphite/PEEK plates subjected to transverse impact loads. The data provide specific information on the effects of impactor velocity, impactor mass, material, thickness of back ply group, difference in fiber orientation between adjacent ply groups, plate thickness, and impactor nose radius. The data were compared to the results of the Finn-Springer model. The model was found to describe the data with reasonable accuracy.

  11. Persistent GMTI surveillance: theoretical performance bounds and some experimental results

    NASA Astrophysics Data System (ADS)

    Balaji, Bhashyam; Damini, Anthony; Wang, Kai

    2010-04-01

    In certain operational radar modes, slow ground moving targets are detected over several processing intervals using space-time adaptive processing. This enables use of Bayesian filtering and smoothing algorithms for estimation of time-varying moving target parameters. In this paper, some Bayesian filtering algorithms are investigated. The Craḿer-Rao bounds based on subsets of radar measurements (range, angle and Doppler) are derived for typical maneuvering targets and compared against simulated results from Bayesian filters. The performance is also evaluated using real data obtained from DRDC Ottawa's XWEAR radar.

  12. Parallel and Distributed Computational Fluid Dynamics: Experimental Results and Challenges

    NASA Technical Reports Server (NTRS)

    Djomehri, Mohammad Jahed; Biswas, R.; VanderWijngaart, R.; Yarrow, M.

    2000-01-01

    This paper describes several results of parallel and distributed computing using a large scale production flow solver program. A coarse grained parallelization based on clustering of discretization grids combined with partitioning of large grids for load balancing is presented. An assessment is given of its performance on distributed and distributed-shared memory platforms using large scale scientific problems. An experiment with this solver, adapted to a Wide Area Network execution environment is presented. We also give a comparative performance assessment of computation and communication times on both the tightly and loosely-coupled machines.

  13. Mars ionosphere: A review of experimental results and modeling studies

    NASA Astrophysics Data System (ADS)

    Haider, S. A.; Mahajan, K. K.; Kallio, E.

    2011-10-01

    In this paper we review results from atmospheric and ionospheric experiments on the early planetary missions like the Mariners, Mars, and Viking 1 and 2 Orbiters/Landers. We then discuss the new results obtained from the two latest missions, namely, the Mars Global Surveyor (MGS) and Mars Express (MEX). The MGS had three ionospheric and atmospheric related experiments, namely, (1) the radio science experiment, which generated 5600 electron density profiles covering a major portion of sunspot cycle 23; (2) the magnetometer/electron reflectometer experiment, which very clearly answered the question about the presence or absence of Martian intrinsic magnetic field; and (3) the accelerometer experiment, which provided a large database of atmospheric density at various Martian locations during the aerobraking phases. The topside sounder on the MEX provided electron density profiles for altitudes above the primary ionospheric peak with a very high time resolution, thereby providing opportunity for exploring ionospheric conditions during events of rapid changes like solar flares. Unlike Venus, where simultaneous electron density, ion density, and magnetic field measurements were made, Mars lacks this kind of information. Consequently, most of our current understanding of Mars' plasma environment is based on theoretical models. We therefore review the various atmospheric and ionospheric models for Mars, which have been generated during the last 4 decades.

  14. Experimental Results of Guided Wave Travel Time Tomography

    NASA Astrophysics Data System (ADS)

    Volker, Arno; Bloom, Joost

    2011-06-01

    Corrosion is one of the industries major issues regarding the integrity of assets. Currently inspections are conducted at regular intervals to ensure a sufficient integrity level of these assets. Cost reduction while maintaining a high level of reliability and safety of installations is a major challenge. The concept of predictive maintenance using permanent sensors that monitor the integrity of an installation matches very well with the objective to reduce cost while maintaining a high safety level. Guided waves are very attractive for permanent monitoring systems because they can travel over large distances and therefore provide the essential large area coverage. Making use of the dispersive behavior of the guided waves, a wall thickness map over a distance of several meters can be made using only two rings of guided wave transducers. Travel time tomography is used to translate transmission travel times into a wall thickness map. This method has been applied in the field for the first time to map the wall thickness under two clearly corroded pipe supports of a 8″ and 10″ gas pipe line. The tomographic inversion results clearly maps the corrosion under the supports. Independent reference measurements confirm the tomographic inversion results.

  15. Space Launch System Base Heating Test: Experimental Operations & Results

    NASA Technical Reports Server (NTRS)

    Dufrene, Aaron; Mehta, Manish; MacLean, Matthew; Seaford, Mark; Holden, Michael

    2016-01-01

    NASA's Space Launch System (SLS) uses four clustered liquid rocket engines along with two solid rocket boosters. The interaction between all six rocket exhaust plumes will produce a complex and severe thermal environment in the base of the vehicle. This work focuses on a recent 2% scale, hot-fire SLS base heating test. These base heating tests are short-duration tests executed with chamber pressures near the full-scale values with gaseous hydrogen/oxygen engines and RSRMV analogous solid propellant motors. The LENS II shock tunnel/Ludwieg tube tunnel was used at or near flight duplicated conditions up to Mach 5. Model development was based on the Space Shuttle base heating tests with several improvements including doubling of the maximum chamber pressures and duplication of freestream conditions. Test methodology and conditions are presented, and base heating results from 76 runs are reported in non-dimensional form. Regions of high heating are identified and comparisons of various configuration and conditions are highlighted. Base pressure and radiometer results are also reported.

  16. IP voice over ATM satellite: experimental results over satellite channels

    NASA Astrophysics Data System (ADS)

    Saraf, Koroush A.; Butts, Norman P.

    1999-01-01

    IP telephony, a new technology to provide voice communication over traditional data networks, has the potential to revolutionize telephone communication within the modern enterprise. This innovation uses packetization techniques to carry voice conversations over IP networks. This packet switched technology promises new integrated services, and lower cost long-distance communication compared to traditional circuit switched telephone networks. Future satellites will need to carry IP traffic efficiently in order to stay competitive in servicing the global data- networking and global telephony infrastructure. However, the effects of Voice over IP over switched satellite channels have not been investigated in detail. To fully understand the effects of satellite channels on Voice over IP quality; several experiments were conducted at Lockheed Martin Telecommunications' Satellite Integration Lab. The result of those experiments along with suggested improvements for voice communication over satellite are presented in this document. First, a detailed introduction of IP telephony as a suitable technology for voice communication over future satellites is presented. This is followed by procedures for the experiments, along with results and strategies. In conclusion we hope that these capability demonstrations will alleviate any uncertainty regarding the applicability of this technology to satellite networks.

  17. Acceleration and torque feedback for robotic control - Experimental results

    NASA Technical Reports Server (NTRS)

    Mclnroy, John E.; Saridis, George N.

    1990-01-01

    Gross motion control of robotic manipulators typically requires significant on-line computations to compensate for nonlinear dynamics due to gravity, Coriolis, centripetal, and friction nonlinearities. One controller proposed by Luo and Saridis avoids these computations by feeding back joint acceleration and torque. This study implements the controller on a Puma 600 robotic manipulator. Joint acceleration measurement is obtained by measuring linear accelerations of each joint, and deriving a computationally efficient transformation from the linear measurements to the angular accelerations. Torque feedback is obtained by using the previous torque sent to the joints. The implementation has stability problems on the Puma 600 due to the extremely high gains inherent in the feedback structure. Since these high gains excite frequency modes in the Puma 600, the algorithm is modified to decrease the gain inherent in the feedback structure. The resulting compensator is stable and insensitive to high frequency unmodeled dynamics. Moreover, a second compensator is proposed which uses acceleration and torque feedback, but still allows nonlinear terms to be fed forward. Thus, by feeding the increment in the easily calculated gravity terms forward, improved responses are obtained. Both proposed compensators are implemented, and the real time results are compared to those obtained with the computed torque algorithm.

  18. Experimental Results from Oak Ridge Isomer Spectrometer and Separator (ORISS)

    NASA Astrophysics Data System (ADS)

    Piechaczek, A.; Batchelder, J. C.; Carter, H. K.; Goans, R. E.; Liu, S.; Shchepunov, V.; Zganjar, E. F.; Unirib Collaboration

    2013-10-01

    ORISS is a linear multi reflection time-of-flight mass analyzer developed by the University Radioactive Ion Beam Consortium. It will be used to separate any isobar and many isomers for decay spectroscopy experiments. The entire system's operation was demonstrated with a less than ideal multi-isotopic ion source and achieved a mass resolving power as high as 430,000. To better characterize the system we have installed a monoisotopic 133Cs ion source. The radiofrequency quadrupole ion cooler and buncher, which serves as the ion injector into ORISS, was tested in stand-alone mode and achieved a longitudinal emittance of 22 π eV × ns and transmission >40%. These very good results confirm our expectation that ORISS can achieve the design goals. Using the improved ion source, we expect, very soon, to demonstrate the complete system's design goals of 400,000 mass resolving power and 50% transmission.

  19. Experimental results on low alpha electron-storage rings

    SciTech Connect

    Robin, D.; Hama, H.; Nadji, A.

    1995-09-01

    The authors report on experiments performed in two synchrotron light sources, UVSOR and Super-ACO, where the momentum compaction factor is reduced in order to reduce the bunch length. By controlling the second-order momentum compaction factor, UVSOR and Super-ACO have managed to reduce the first-order momentum compaction factor by 100. At low current the resulting bunch lengths are less than 10 ps, a factor of 10 smaller than normal. Measurements of current dependent bunch lengthening in UVSOR are presented and the cause of the bunch lengthening is determined to be potential-well distortion. The authors also show that by operating with a negative momentum compaction factor, SuperACO has achieved shorter bunch lengthening and higher peak currents than at positive momentum compaction.

  20. Microgravity Fluid Separation Physics: Experimental and Analytical Results

    NASA Technical Reports Server (NTRS)

    Shoemaker, J. Michael; Schrage, Dean S.

    1997-01-01

    Effective, low power, two-phase separation systems are vital for the cost-effective study and utilization of two-phase flow systems and flow physics of two-phase flows. The study of microgravity flows have the potential to reveal significant insight into the controlling mechanisms for the behavior of flows in both normal and reduced gravity environments. The microgravity environment results in a reduction in gravity induced buoyancy forces acting on the discrete phases. Thus, surface tension, viscous, and inertial forces exert an increased influence on the behavior of the flow as demonstrated by the axisymmetric flow patterns. Several space technology and operations groups have studied the flow behavior in reduced gravity since gas-liquid flows are encountered in several systems such as cabin humidity control, wastewater treatment, thermal management, and Rankine power systems.

  1. Wide-field Fizeau imaging telescope: experimental results.

    PubMed

    Kendrick, R L; Aubrun, Jean-Noel; Bell, Ray; Benson, Robert; Benson, Larry; Brace, David; Breakwell, John; Burriesci, Larry; Byler, Eric; Camp, John; Cross, Gene; Cuneo, Peter; Dean, Peter; Digumerthi, Ramji; Duncan, Alan; Farley, John; Green, Andy; Hamilton, Howard H; Herman, Bruce; Lauraitis, Kris; de Leon, Erich; Lorell, Kenneth; Martin, Rob; Matosian, Ken; Muench, Tom; Ni, Mel; Palmer, Alice; Roseman, Dennis; Russell, Sheldon; Schweiger, Paul; Sigler, Rob; Smith, John; Stone, Richard; Stubbs, David; Swietek, Gregg; Thatcher, John; Tischhauser, C; Wong, Harvey; Zarifis, Vassilis; Gleichman, Kurt; Paxman, Rick

    2006-06-20

    A nine-aperture, wide-field Fizeau imaging telescope has been built at the Lockheed-Martin Advanced Technology Center. The telescope consists of nine, 125 mm diameter collector telescopes coherently phased and combined to form a diffraction-limited image with a resolution that is consistent with the 610 mm diameter of the telescope. The phased field of view of the array is 1 murad. The measured rms wavefront error is 0.08 waves rms at 635 nm. The telescope is actively controlled to correct for tilt and phasing errors. The control sensing technique is the method known as phase diversity, which extracts wavefront information from a pair of focused and defocused images. The optical design of the telescope and typical performance results are described. PMID:16778931

  2. New experimental results in atlas-based brain morphometry

    NASA Astrophysics Data System (ADS)

    Gee, James C.; Fabella, Brian A.; Fernandes, Siddharth E.; Turetsky, Bruce I.; Gur, Ruben C.; Gur, Raquel E.

    1999-05-01

    In a previous meeting, we described a computational approach to MRI morphometry, in which a spatial warp mapping a reference or atlas image into anatomic alignment with the subject is first inferred. Shape differences with respect to the atlas are then studied by calculating the pointwise Jacobian determinant for the warp, which provides a measure of the change in differential volume about a point in the reference as it transforms to its corresponding position in the subject. In this paper, the method is used to analyze sex differences in the shape and size of the corpus callosum in an ongoing study of a large population of normal controls. The preliminary results of the current analysis support findings in the literature that have observed the splenium to be larger in females than in males.

  3. M-I-S solar cell - Theory and experimental results

    NASA Technical Reports Server (NTRS)

    Childs, R.; Fortuna, J.; Geneczko, J.; Fonash, S. J.

    1976-01-01

    The paper presents an operating-mode analysis of an MIS solar cell and discusses the advantages which can arise as a result of the use of transport control, field shaping (increased n factor), and zero bias barrier height modification. It is noted that for an n-type semiconductor, it is relatively easy to obtain an enhanced n factor using acceptor-like states without an increase in diode saturation current, the converse being true for p-type semiconductors. Several MIS configurations are examined: an acceptor-like, localized state configuration producing field shaping and no change in diode saturation current, and acceptor-like localized configurations producing field shaping, with a decrease of diode saturation current, in one case, and an increase in the other.

  4. Experimental Results in DIS, SIDIS and DES from Jefferson Lab

    SciTech Connect

    Kuhn, Sebastian E.

    2011-07-15

    Jefferson Lab's electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering--DIS--at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum-dependent (TMD) structure functions using Semi-Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic space will become available. The 12 GeV program taking shape will complete a detailed mapping of inclusive, TMD and generalized distribution functions for quarks, antiquarks and gluons in the valence region and beyond.

  5. Experimental Results in DIS, SIDIS and DES from Jefferson Lab

    SciTech Connect

    Sebastian Kuhn

    2011-07-01

    Jefferson Lab's electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum-dependent (TMD) structure functions using Semi-Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic space will become available. The 12 GeV program taking shape will complete a detailed mapping of inclusive, TMD and generalized distribution functions for quarks, antiquarks and gluons in the valence region and beyond.

  6. Longitudinal variation of the equatorial ionosphere: Modeling and experimental results

    NASA Astrophysics Data System (ADS)

    Souza, J. R.; Asevedo, W. D.; dos Santos, P. C. P.; Petry, A.; Bailey, G. J.; Batista, I. S.; Abdu, M. A.

    2013-02-01

    We describe a new version of the Parameterized Regional Ionospheric Model (PARIM) which has been modified to include the longitudinal dependences. This model has been reconstructed using multidimensional Fourier series. To validate PARIM results, the South America maps of critical frequencies for the E (foE) and F (foF2) regions were compared with the values calculated by Sheffield Plasmasphere-Ionosphere Model (SUPIM) and IRI representations. PARIM presents very good results, the general characteristics of both regions, mainly the presence of the equatorial ionization anomaly, were well reproduced for equinoctial conditions of solar minimum and maximum. The values of foF2 and hmF2 recorded over Jicamarca (12°S; 77°W; dip lat. 1°N; mag. declination 0.3°) and sites of the conjugate point equatorial experiment (COPEX) campaign Boa Vista (2.8°N; 60.7°W; dip lat. 11.4°; mag. declination -13.1°), Cachimbo (9.5°S; 54.8°W; dip lat. -1.8°; mag. declination -15.5°), and Campo Grande (20.4°S; 54.6°W; dip lat. -11.1°; mag. declination -14.0°) have been used in this work. foF2 calculated by PARIM show good agreement with the observations, except during morning over Boa Vista and midnight-morning over Campo Grande. Some discrepancies were also found for the F-region peak height (hmF2) near the geomagnetic equator during times of F3 layer occurrences. IRI has underestimated both foF2 and hmF2 over equatorial and low latitude sectors during evening-nighttimes, except for Jicamarca where foF2 values were overestimated.

  7. Experimental results: Pilot plant calcine dissolution and liquid feed stability

    SciTech Connect

    Herbst, R.S.; Fryer, D.S.; Brewer, K.N.; Johnson, C.K.; Todd, T.A.

    1995-02-01

    The dissolution of simulated Idaho Chemical Processing Plant pilot plant calcines, containing none of the radioactive actinides, lanthanides or fission products, was examined to evaluate the solubility of calcine matrix materials in acidic media. This study was a necessary precursor to dissolution and optimization experiments with actual radionuclide-containing calcines. The importance of temperature, nitric acid concentration, ratio of acid volume to calcine mass, and time on the amount, as a weight percentage of calcine dissolved, was evaluated. These parameters were studied for several representative pilot plant calcine types: (1) Run No. 74 Zirconia calcine; (2) Run No. 17 Zirconia/Sodium calcine; (3) Run No. 64 Zirconia/Sodium calcine; (3) Run No. 1027 Alumina calcine; and (4) Run No. 20 Alumina/Zirconia/Sodium calcine. Statistically designed experiments with the different pilot plant calcines indicated the effect of the studied process variables on the amount of calcine dissolved decreases in the order: Acid/Calcine Ratio > Temperature > HNO{sub 3} Concentration > Dissolution Time. The following conditions are suitable to achieve greater than 90 wt. % dissolution of most Zr, Al, or Na blend calcines: (1) Maximum nitric acid concentration of 5M; (2) Minimum acid/calcine ratio of 10 mL acid/1 gram calcine; (3) Minimum dissolution temperature of 90{degrees}C; and (4) Minimum dissolution time of 30 minutes. The formation of calcium sulphate (CaSO{sub 4}) precipitates was observed in certain dissolved calcine solutions during the dissolution experiments. Consequently, a study was initiated to evaluate if and under what conditions the resulting dissolved calcine solutions would be unstable with regards to precipitate formation. The results indicate that precipitate formation in the calcine solutions prepared under the above proposed dissolution conditions are not anticipated.

  8. First experimental results on the IShTAR testbed

    NASA Astrophysics Data System (ADS)

    D'Inca, R.; Jacquot, J.; Ochoukov, R.; Morgal, I.; Crombe, K.; Louche, F.; Van Eester, D.; Heuraux, S.; Devaux, S.; Moritz, J.; Faudot, E.; Fünfgelder, H.; Faugel, H.; Noterdaeme, J.-M.

    2015-12-01

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetized plasma test facility dedicated to the investigation of RF wave/plasma interaction [1] in the Ion Cyclotron Range of Frequencies (ICRF). It provides a better accessibility for the instrumentation than tokamaks while being representative of the neighboring region of the wave emitter. It is equipped with a magnetized plasma source (1 m long, 0.4 m diameter) powered by a helical antenna up to 3 kW at 11 MHz. We present the results of the first analysis of the plasma characteristics (plasma density, electron temperature) in function of the operating parameters (injected power, neutral pressure and magnetic field) as measured with fixed and movable Langmuir probes, spectrometer and cameras. The plasma is presently produced only by the helical antenna (no ICRF). We show that the plasma exists in three regime depending on the power level: the first two ones are stable and separated by a jump in density; a first spatial profile of the plasma density has been established for these modes; The third mode is unstable, characterized by strong oscillations of the plasma tube position.

  9. Experimental Results of Integrated Refrigeration and Storage System Testing

    NASA Technical Reports Server (NTRS)

    Notardonato, W. U.; Johnson, W. L.; Jumper, K.

    2009-01-01

    Launch operations engineers at the Kennedy Space Center have identified an Integrated Refrigeration and Storage system as a promising technology to reduce launch costs and enable advanced cryogenic operations. This system uses a close cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for the potential of a zero loss storage and transfer system, as well and control of the state of the propellant through densification or re-liquefaction. However, the behavior of the fluid in this type of system is different than typical cryogenic behavior, and there will be a learning curve associated with its use. A 400 liter research cryostat has been designed, fabricated and delivered to KSC to test the thermo fluid behavior of liquid oxygen as energy is removed from the cryogen by a simulated DC cycle cryocooler. Results of the initial testing phase focusing on heat exchanger characterization and zero loss storage operations using liquid oxygen are presented in this paper. Future plans for testing of oxygen densification tests and oxygen liquefaction tests will also be discussed. KEYWORDS: Liquid Oxygen, Refrigeration, Storage

  10. Experimental Results on Electrorheology of Liquid Crystalline Polymer Solutions

    NASA Astrophysics Data System (ADS)

    Neves, S.; Leal, C. R.; Cidade, M. T.

    2008-07-01

    The electrorheological (ER) effect is known as the enhancement of the apparent viscosity upon application of an external electric field. Suspensions of polarizable particles in non-conducting solvents are the most studied electrorheological fluids, however, liquid crystalline materials may also present ER effect as long as their dielectric anisotropy is positive. In the liquid crystalline state of a positive dielectric anisotropy, the application of the electric field makes the director align perpendicular to the flow direction, thus increasing the apparent viscosity. In this work results of two liquid crystalline polymer solutions, acetoxypropylcellulose (APC) in dimethylacetamide (DMAc) and poly-γ-benzyl-L-glutamate (PBLG) in 1,4-dioxane, presenting opposite behavior upon application of the electric field, will be presented. APC/DMAc (negative dielectric anisotropy) presents a decrease of the apparent viscosity upon application of the electric field, as expected, while PBLG/1,4-dioxane (positive dielectric anisotropy) presents the opposite behavior. For this last solution we will present the shear flow curves for different electric fields in function of polymer molecular weight and solution concentration.

  11. The experimental results and analysis of a borehole radar prototype

    NASA Astrophysics Data System (ADS)

    Liu, Sixin; Wu, Junjun; Dong, Hang; Fu, Lei; Wang, Fei

    2012-04-01

    A prototype of borehole radar has been successfully tested in three sites for different purposes under a field condition. The objective of the prototype is providing an effective down-hole tool for detecting targets in deep boreholes situated in a relatively high conductivity area such as the metal ores. The first testing site is at a geothermal field. The fractures extending more than 20 m from the borehole are delineated by the borehole radar in the single-hole reflection mode. The second testing site is located in a jade mine for basement evaluation. The cross-hole measurement mode was used to detect the cavities made by previous unorganized mining activities. Several high-velocity anomalies were found in the velocity profile and presumably the targets of the mine shafts and tunnels. The third test site is located in a mineralized belt characterized by low resistivity less than 1000 Ohm m, the surface-borehole measurement was carried out and the data were processed with velocity tomography. The low-velocity zone corresponds to a mineralized zone from geological records. The three testing results proved the readiness of this borehole radar prototype for further deployment in more complicated and realistic field situations.

  12. Infrared thermography for CFRP inspection: computational model and experimental results

    NASA Astrophysics Data System (ADS)

    Fernandes, Henrique C.; Zhang, Hai; Morioka, Karen; Ibarra-Castanedo, Clemente; López, Fernando; Maldague, Xavier P. V.; Tarpani, José R.

    2016-05-01

    Infrared Thermography (IRT) is a well-known Non-destructive Testing (NDT) technique. In the last decades, it has been widely applied in several fields including inspection of composite materials (CM), specially the fiber-reinforced polymer matrix ones. Consequently, it is important to develop and improve efficient NDT techniques to inspect and assess the quality of CM parts in order to warranty airworthiness and, at the same time, reduce costs of airline companies. In this paper, active IRT is used to inspect carbon fiber-reinforced polymer (CFRP) at laminate with artificial inserts (built-in sample) placed on different layers prior to the manufacture. Two optical active IRT are used. The first is pulsed thermography (PT) which is the most widely utilized IRT technique. The second is a line-scan thermography (LST) technique: a dynamic technique, which can be employed for the inspection of materials by heating a component, line-by-line, while acquiring a series of thermograms with an infrared camera. It is especially suitable for inspection of large parts as well as complex shaped parts. A computational model developed using COMSOL Multiphysics® was used in order to simulate the inspections. Sequences obtained from PT and LST were processed using principal component thermography (PCT) for comparison. Results showed that it is possible to detect insertions of different sizes at different depths using both PT and LST IRT techniques.

  13. First experimental results on the IShTAR testbed

    SciTech Connect

    D’Inca, R.; Jacquot, J.; Ochoukov, R.; Morgal, I.; Fünfgelder, H.; Faugel, H.; Crombe, K.; Louche, F.; Van Eester, D.; Heuraux, S.; Devaux, S.; Moritz, J.; Faudot, E.; Noterdaeme, J.-M.

    2015-12-10

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetized plasma test facility dedicated to the investigation of RF wave/plasma interaction [1] in the Ion Cyclotron Range of Frequencies (ICRF). It provides a better accessibility for the instrumentation than tokamaks while being representative of the neighboring region of the wave emitter. It is equipped with a magnetized plasma source (1 m long, 0.4 m diameter) powered by a helical antenna up to 3 kW at 11 MHz. We present the results of the first analysis of the plasma characteristics (plasma density, electron temperature) in function of the operating parameters (injected power, neutral pressure and magnetic field) as measured with fixed and movable Langmuir probes, spectrometer and cameras. The plasma is presently produced only by the helical antenna (no ICRF). We show that the plasma exists in three regime depending on the power level: the first two ones are stable and separated by a jump in density; a first spatial profile of the plasma density has been established for these modes; The third mode is unstable, characterized by strong oscillations of the plasma tube position.

  14. Impact ejecta dynamics in an atmosphere - Experimental results and extrapolations

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.; Gault, D. E.

    1982-01-01

    It is noted that the impacts of 0.635-cm aluminum projectiles at 6 km/sec into fine pumice dust, at 1 atm, generate a ball of ionized gas behind an expanding curtain of upward moving ejecta. The gas ball forms a toroid which dissolves as it is driven along the interior of the ejecta curtain, by contrast to near-surface explosions in which a fireball envelops early-time crater growth. High frame rate Schlieren photographs show that the atmosphere at the base of the ejecta curtain is initially turbulent, but later forms a vortex. These experiments suggest that although small size ejecta may be decelerated by air drag, they are not simply lofted and suspended but become incorporated in an ejecta cloud that is controlled by air flow which is produced by the response of the atmosphere to the impact. The extrapolation of these results to large body impacts on the earth suggests such contrasts with laboratory experiments as a large quantity of impact-generated vapor, the supersonic advance of the ejecta curtain, the lessened effect of air drag due to the tenuous upper atmosphere, and the role of secondary cratering.

  15. Bridge Testing With Ground-Based Interferometric Radar: Experimental Results

    NASA Astrophysics Data System (ADS)

    Chiara, P.; Morelli, A.

    2010-05-01

    The research of innovative non-contact techniques aimed at the vibration measurement of civil engineering structures (also for damage detection and structural health monitoring) is continuously directed to the optimization of measures and methods. Ground-Based Radar Interferometry (GBRI) represents the more recent technique available for static and dynamic control of structures and ground movements. Dynamic testing of bridges and buildings in operational conditions are currently performed: (a) to assess the conformity of the structure to the project design at the end of construction; (b) to identify the modal parameters (i.e. natural frequencies, mode shapes and damping ratios) and to check the variation of any modal parameters over the years; (c) to evaluate the amplitude of the structural response to special load conditions (i.e. strong winds, earthquakes, heavy railway or roadway loads). If such tests are carried out by using a non-contact technique (like GBRI), the classical issues of contact sensors (like accelerometers) are easily overtaken. This paper presents and discusses the results of various tests carried out on full-scale bridges by using a Stepped Frequency-Continuous Wave radar system.

  16. Bridge Testing With Ground-Based Interferometric Radar: Experimental Results

    SciTech Connect

    Chiara, P.; Morelli, A.

    2010-05-28

    The research of innovative non-contact techniques aimed at the vibration measurement of civil engineering structures (also for damage detection and structural health monitoring) is continuously directed to the optimization of measures and methods. Ground-Based Radar Interferometry (GBRI) represents the more recent technique available for static and dynamic control of structures and ground movements.Dynamic testing of bridges and buildings in operational conditions are currently performed: (a) to assess the conformity of the structure to the project design at the end of construction; (b) to identify the modal parameters (i.e. natural frequencies, mode shapes and damping ratios) and to check the variation of any modal parameters over the years; (c) to evaluate the amplitude of the structural response to special load conditions (i.e. strong winds, earthquakes, heavy railway or roadway loads). If such tests are carried out by using a non-contact technique (like GBRI), the classical issues of contact sensors (like accelerometers) are easily overtaken.This paper presents and discusses the results of various tests carried out on full-scale bridges by using a Stepped Frequency-Continuous Wave radar system.

  17. Sodium-layer laser-guide-star experimental results

    SciTech Connect

    Avicola, K.; Brase, J.M.; Morris, J.R.

    1994-02-01

    The authors describe a series of experiments to characterize the sodium-layer guide star that was formed with the highpower laser developed for the Lawrence Livermore National Laboratory Atomic Vapor Laser Isotope Separation program. An emission spot size of 3.0 m was measured, with an implied laser irradiance spot diameter of 2.0 m. The rms spot motion at the higher laser powers, with active beam-pointing control, was less than 0.5 arcsec and had little effect on the observed spot size under these conditions. The authors measured the resonant backscatter from the sodium layer as a function of laser power to obtain a saturation curve. With a transmitted power of 1100 W and an atmospheric transmission of 0.6, the irradiance from the guide star at the ground was 10 (photons/cm{sup 2})/ms, corresponding to a visual magnitude of 5.1. The implications for the performance of wave-front sensors with a laser guide star of this magnitude and resulting closed-loop adaptive-optics performance are discussed. 13 refs., 9 figs.

  18. EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY

    SciTech Connect

    Fox, K.; Edwards, T.

    2009-11-09

    This study is the third phase in a series of experiments designed to reduce conservatism in the model that predicts the formation of nepheline, a crystalline phase that can reduce the durability of high level waste glass. A Phase I study developed a series of glass compositions that were very durable while their nepheline discriminator values were well below the current nepheline discriminator limit of 0.62, where nepheline is predicted to crystallize upon slow cooling. A Phase II study selected glass compositions to identify any linear effects of composition on nepheline crystallization and that were restricted to regions that fell within the validation ranges of the Defense Waste Processing Facility (DWPF) Product Composition Control System (PCCS) models. However, it was not possible to identify any linear effects of composition on chemical durability performance for this set of study glasses. The results of the Phase II study alone were not sufficient to recommend modification of the current nepheline discriminator. It was recommended that the next series of experiments continue to focus not only on compositional regions where the PCCS models are considered applicable (i.e., the model validation ranges), but also be restricted to compositional regions where the only constraint limiting processing is the current nepheline discriminator. Two methods were used in selecting glasses for this Phase III nepheline study. The first was based on the relationship of the current nepheline discriminator model to the other DWPF PCCS models, and the second was based on theory of crystallization in mineral and glass melts. A series of 29 test glass compositions was selected for this study using a combination of the two approaches. The glasses were fabricated and characterized in the laboratory. After reviewing the data, the study glasses generally met the target compositions with little issue. Product Consistency Test results correlated well with the crystallization analyses in

  19. OPERA and MINOS Experimental Result Prove Big Bang Theory Invalid

    NASA Astrophysics Data System (ADS)

    Pressler, David E.

    2012-03-01

    The greatest error in the history of science is the misinterpretation of the Michelson-Morley Experiment. The speed of light was measured to travel at the same speed in all three directions (x, y, z axis) in ones own inertial reference system; however, c will always be measured as having an absolute different speed in all other inertial frames at different energy levels. Time slows down due to motion or a gravity field. Time is the rate of physical process. Speed = Distance/Time. If the time changes the distance must change. Therefore, BOTH mirrors must move towards the center of the interferometer and space must contract in all-three-directions; C-Space. Gravity is a C-Space condition, and is the cause of redshift in our universe-not motion. The universe is not expanding. OPERA results are directly indicated; at the surface of earth, the strength of the gravity field is at maximum-below the earth's surface, time and space is less distorted, C-Space; therefore, c is faster. Newtonian mechanics dictate that a spherical shell of matter at greater radii, with uniform density, produces no net force on an observer located centrally. An observer located on the sphere's surface, like our Earth's or a large sphere, like one located in a remote galaxy, will construct a picture centered on himself to be identical to the one centered inside the spherical shell of mass. Both observers will view the incoming radiation, emitted by the other observer, as redshifted, because they lay on each others radial line. The Universe is static and very old.

  20. Experimental study on the application of a compressed-sensing (CS) algorithm to dental cone-beam CT (CBCT) for accurate, low-dose image reconstruction

    NASA Astrophysics Data System (ADS)

    Oh, Jieun; Cho, Hyosung; Je, Uikyu; Lee, Minsik; Kim, Hyojeong; Hong, Daeki; Park, Yeonok; Lee, Seonhwa; Cho, Heemoon; Choi, Sungil; Koo, Yangseo

    2013-03-01

    In practical applications of three-dimensional (3D) tomographic imaging, there are often challenges for image reconstruction from insufficient data. In computed tomography (CT); for example, image reconstruction from few views would enable fast scanning with reduced doses to the patient. In this study, we investigated and implemented an efficient reconstruction method based on a compressed-sensing (CS) algorithm, which exploits the sparseness of the gradient image with substantially high accuracy, for accurate, low-dose dental cone-beam CT (CBCT) reconstruction. We applied the algorithm to a commercially-available dental CBCT system (Expert7™, Vatech Co., Korea) and performed experimental works to demonstrate the algorithm for image reconstruction in insufficient sampling problems. We successfully reconstructed CBCT images from several undersampled data and evaluated the reconstruction quality in terms of the universal-quality index (UQI). Experimental demonstrations of the CS-based reconstruction algorithm appear to show that it can be applied to current dental CBCT systems for reducing imaging doses and improving the image quality.

  1. Accurate experimental determination of the isotope effects on the triple point temperature of water. I. Dependence on the 2H abundance

    NASA Astrophysics Data System (ADS)

    Faghihi, V.; Peruzzi, A.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; van Geel, J.; Meijer, H. A. J.

    2015-12-01

    Variation in the isotopic composition of water is one of the major contributors to uncertainty in the realization of the triple point of water (TPW). Although the dependence of the TPW on the isotopic composition of the water has been known for years, there is still a lack of a detailed and accurate experimental determination of the values for the correction constants. This paper is the first of two articles (Part I and Part II) that address quantification of isotope abundance effects on the triple point temperature of water. In this paper, we describe our experimental assessment of the 2H isotope effect. We manufactured five triple point cells with prepared water mixtures with a range of 2H isotopic abundances encompassing widely the natural abundance range, while the 18O and 17O isotopic abundance were kept approximately constant and the 18O  -  17O ratio was close to the Meijer-Li relationship for natural waters. The selected range of 2H isotopic abundances led to cells that realised TPW temperatures between approximately  -140 μK to  +2500 μK with respect to the TPW temperature as realized by VSMOW (Vienna Standard Mean Ocean Water). Our experiment led to determination of the value for the δ2H correction parameter of A2H  =  673 μK / (‰ deviation of δ2H from VSMOW) with a combined uncertainty of 4 μK (k  =  1, or 1σ).

  2. Experimental results from a preclinical X-ray phase-contrast CT scanner

    PubMed Central

    Tapfer, Arne; Bech, Martin; Velroyen, Astrid; Meiser, Jan; Mohr, Jürgen; Walter, Marco; Schulz, Joachim; Pauwels, Bart; Bruyndonckx, Peter; Liu, Xuan; Sasov, Alexander; Pfeiffer, Franz

    2012-01-01

    To explore the future clinical potential of improved soft-tissue visibility with grating-based X-ray phase contrast (PC), we have developed a first preclinical computed tomography (CT) scanner featuring a rotating gantry. The main challenge in the transition from previous bench-top systems to a preclinical scanner are phase artifacts that are caused by minimal changes in the grating alignment during gantry rotation. In this paper, we present the first experimental results from the system together with an adaptive phase recovery method that corrects for these phase artifacts. Using this method, we show that the scanner can recover quantitatively accurate Hounsfield units in attenuation and phase. Moreover, we present a first tomography scan of biological tissue with complementary information in attenuation and phase contrast. The present study hence demonstrates the feasibility of grating-based phase contrast with a rotating gantry for the first time and paves the way for future in vivo studies on small animal disease models (in the mid-term future) and human diagnostics applications (in the long-term future). PMID:23019354

  3. A comparison of experimental and theoretical results for labyrinth gas seals with honeycomb stators. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Hawkins, Lawrence Allen

    1988-01-01

    Experimental results for the rotordynamic stiffness and damping coefficients of a labyrinth -rotor honeycomb-stator seal are presented. The coefficients are compared to the coefficients of a labyrinth-rotor smooth-stator seal having the same geometry. The coefficients are compared to analytical results from a two-control-volume compressible flow model. The experimental results show that the honeycomb stator configuration is more stable than the smooth stator configuration at low rotor speeds. At high rotor speeds and low clearance, the smooth stator seal is more stable. The theoretical model predicts the cross-coupled stiffness of the honeycomb stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

  4. Experimental results for labyrinth gas seals with honeycomb stators - Comparisons to smooth-stator seals and theoretical predictions

    NASA Technical Reports Server (NTRS)

    Hawkins, Larry; Childs, Dara; Hale, Keith

    1989-01-01

    Experimental measurements are presented for the rotordynamic stiffness and damping coefficients of a teeth-on-rotor labyrinth seal with a honeycomb stator. Inlet circumferential velocity, inlet pressure, rotor speed, and seal clearance are primary variables. Results are compared to data for teeth-on-rotor labyrinth seals with smooth stators and to analytical predictions from a two-control-volume compressible flow model. The experimental results show that the honeycomb-stator configuration is more stable than the smooth-stator configuration at low rator speeds. At high rotor speeds, the stator surface does not affect stability. The theoretical model predicts the cross-coupled stiffness of the honeycomb-stator seal correctly within 25 percent of measured values. The model provides accurate predictions of direct damping for large clearance seals; however, the model predictions and test results diverge with increasing running speed. Overall, the model does not perform as well for low clearance seals as for high clearance seals.

  5. Accurate measurements of vadose zone fluxes using automated equilibrium tension plate lysimeters: A synopsis of results from the Spydia research facility, New Zealand.

    NASA Astrophysics Data System (ADS)

    Wöhling, Thomas; Barkle, Greg; Stenger, Roland; Moorhead, Brian; Wall, Aaron; Clague, Juliet

    2014-05-01

    Automated equilibrium tension plate lysimeters (AETLs) are arguably the most accurate method to measure unsaturated water and contaminant fluxes below the root zone at the scale of up to 1 m². The AETL technique utilizes a porous sintered stainless-steel plate to provide a comparatively large sampling area with a continuously controlled vacuum that is in "equilibrium" with the surrounding vadose zone matric pressure to ensure measured fluxes represent those under undisturbed conditions. This novel lysimeter technique was used at an intensive research site for investigations of contaminant pathways from the land surface to the groundwater on a sheep and beef farm under pastoral land use in the Tutaeuaua subcatchment, New Zealand. The Spydia research facility was constructed in 2005 and was fully operational between 2006 and 2011. Extending from a central access caisson, 15 separately controlled AETLs with 0.2 m² surface area were installed at five depths between 0.4 m and 5.1 m into the undisturbed volcanic vadose zone materials. The unique setup of the facility ensured minimum interference of the experimental equipment and external factors with the measurements. Over the period of more than five years, a comprehensive data set was collected at each of the 15 AETL locations which comprises of time series of soil water flux, pressure head, volumetric water contents, and soil temperature. The soil water was regularly analysed for EC, pH, dissolved carbon, various nitrogen compounds (including nitrate, ammonia, and organic N), phosphorus, bromide, chloride, sulphate, silica, and a range of other major ions, as well as for various metals. Climate data was measured directly at the site (rainfall) and a climate station at 500m distance. The shallow groundwater was sampled at three different depths directly from the Spydia caisson and at various observation wells surrounding the facility. Two tracer experiments were conducted at the site in 2009 and 2010. In the 2009

  6. Implementation and experimental results of 4D tumor tracking using robotic couch

    SciTech Connect

    Buzurovic, I.; Yu, Y.; Werner-Wasik, M.; Biswas, T.; Anne, P. R.; Dicker, A. P.; Podder, T. K.

    2012-11-15

    Purpose: This study presents the implementation and experimental results of a novel technique for 4D tumor tracking using a commercially available and commonly used treatment couch and evaluates the tumor tracking accuracy in clinical settings. Methods: Commercially available couch is capable of positioning the patient accurately; however, currently there is no provision for compensating physiological movement using the treatment couch in real-time. In this paper, a real-time couch tracking control technique is presented together with experimental results in tumor motion compensation in four dimensions (superior-inferior, lateral, anterior-posterior, and time). To implement real-time couch motion for tracking, a novel control system for the treatment couch was developed. The primary functional requirements for this novel technique were: (a) the treatment couch should maintain all previous/normal features for patient setup and positioning, (b) the new control system should be used as a parallel system when tumor tracking would be deployed, and (c) tracking could be performed in a single direction and/or concurrently in all three directions of the couch motion (longitudinal, lateral, and vertical). To the authors' best knowledge, the implementation of such technique to a regular treatment couch for tumor tracking has not been reported so far. To evaluate the performance of the tracking couch, we investigated the mechanical characteristics of the system such as system positioning resolution, repeatability, accuracy, and tracking performance. Performance of the tracking system was evaluated using dosimetric test as an endpoint. To investigate the accuracy of real-time tracking in the clinical setting, the existing clinical treatment couch was replaced with our experimental couch and the linear accelerator was used to deliver 3D conformal radiation therapy (3D-CRT) and intensity modulated radiation therapy (IMRT) treatment plans with and without tracking. The results of

  7. Inter-species extrapolation of skin heating resulting from millimeter wave irradiation: modeling and experimental results.

    PubMed

    Nelson, D A; Walters, T J; Ryan, K L; Emerton, K B; Hurt, W D; Ziriax, J M; Johnson, L R; Mason, P A

    2003-05-01

    This study reports measurements of the skin surface temperature elevations during localized irradiation (94 GHz) of three species: rat (irradiated on lower abdomen), rhesus monkey (posterior forelimb), and human (posterior forearm). Two exposure conditions were examined: prolonged, low power density microwaves (LPM) and short-term, high power density microwaves (HPM). Temperature histories were compared with calculations from a bio-heat transfer model. The mean peak surface temperature increase was approximately 7.0 degrees C for the short-term HPM exposures for all three species/locations, and 8.5 degrees C (monkey, human) to 10.5 degrees C (rat) for the longer-duration LPM exposures. The HPM temperature histories are in close agreement with a one-dimensional conduction heat transfer model with negligible blood flow. The LPM temperature histories were compared with calculations from the bio-heat model, evaluated for various (constant) blood flow rates. Results suggest a variable blood flow model, reflecting a dynamic thermoregulatory response, may be more suited to describing skin surface temperature response under long-duration MMW irradiation. PMID:12747480

  8. A comparative study between experimental results and numerical predictions of multi-wall structural response to hypervelocity impact

    NASA Technical Reports Server (NTRS)

    Schonberg, William P.; Peck, Jeffrey A.

    1992-01-01

    Over the last three decades, multiwall structures have been analyzed extensively, primarily through experiment, as a means of increasing the protection afforded to spacecraft structure. However, as structural configurations become more varied, the number of tests required to characterize their response increases dramatically. As an alternative, numerical modeling of high-speed impact phenomena is often being used to predict the response of a variety of structural systems under impact loading conditions. This paper presents the results of a preliminary numerical/experimental investigation of the hypervelocity impact response of multiwall structures. The results of experimental high-speed impact tests are compared against the predictions of the HULL hydrodynamic computer code. It is shown that the hypervelocity impact response characteristics of a specific system cannot be accurately predicted from a limited number of HULL code impact simulations. However, if a wide range of impact loadings conditions are considered, then the ballistic limit curve of the system based on the entire series of numerical simulations can be used as a relatively accurate indication of actual system response.

  9. Accurate experimental determination of the isotope effects on the triple point temperature of water. II. Combined dependence on the 18O and 17O abundances

    NASA Astrophysics Data System (ADS)

    Faghihi, V.; Kozicki, M.; Aerts-Bijma, A. T.; Jansen, H. G.; Spriensma, J. J.; Peruzzi, A.; Meijer, H. A. J.

    2015-12-01

    This paper is the second of two articles on the quantification of isotope effects on the triple point temperature of water. In this second article, we address the combined effects of 18O and 17O isotopes. We manufactured five triple point cells with waters with 18O and 17O abundances exceeding widely the natural abundance range while maintaining their natural 18O/17O relationship. The 2H isotopic abundance was kept close to that of VSMOW (Vienna Standard Mean Ocean Water). These cells realized triple point temperatures ranging between  -220 μK to 1420 μK with respect to the temperature realized by a triple point cell filled with VSMOW. Our experiment allowed us to determine an accurate and reliable value for the newly defined combined 18, 17O correction parameter of AO  =  630 μK with a combined uncertainty of 10 μK. To apply this correction, only the 18O abundance of the TPW needs to be known (and the water needs to be of natural origin). Using the results of our two articles, we recommend a correction equation along with the coefficient values for isotopic compositions differing from that of VSMOW and compare the effect of this new equation on a number of triple point cells from the literature and from our own institute. Using our correction equation, the uncertainty in the isotope correction for triple point cell waters used around the world will be  <1 μK.

  10. Results from experimental investigations of the performance of air condensers for steam turbine units

    NASA Astrophysics Data System (ADS)

    Fedorov, V. A.; Mil'man, O. O.; Kolesnikov, N. V.; Anan'ev, P. A.; Dunaev, S. N.; Mikhal'kov, A. M.; Mosin, A. V.; Kondrat'ev, A. V.

    2013-02-01

    Results from experimental investigations of the model versions of Type ABC GI air condensers are presented, and it is shown that these condensers have better performance characteristics as compared with their analogs that are currently in operation.

  11. A Fast and Accurate Monte Carlo EAS Simulation Scheme in the GZK Energy Region and Some Results for the TA experiment

    NASA Astrophysics Data System (ADS)

    Cohen, F.; Kasahara, K.

    As described in an accompanying paper (kasahara), full M.C simulation of air showers in the GZK region is possible by a distributed-parallel processing method. However, this still needs a long computation time even with ~50 to ~100 cpu's which may be available in many pc cluster environments. Air showers always fluctuate event to event largely, and only 1 or few events are not appropriate for practical application. However, we may note that the fluctuations appear only in the longitudinal development; if we look into the ingredients (energy spectrum, angular distribution, arrival time distribution etc and their correlations) at the same "age" of the shower, they are almost the same (or at least can be scaled; e.g, for the lateral distribution, we may use appropriate Moliere length ). In some cases (for muons and hadrons), we may use another parameter instead of the "age". Based on this fact, we developed a new fast and accurate M.C simulation scheme which utilizes a database in which full M.C results are stored (FDD). We generate a number of air showers by using the usual thin sampling method. The thin sampling is sometimes very dangerous when we discuss detailed ingredient (say,lateral distribution, energy spectrum, their correlations etc) but is safely employed to see the total number of particles in the longitudinal development (LDD; we can generate ~1000 LDD showers by 50 cpu's in a day). Then, for a given 1 particular such an event at a certain depth, we can extract every details from FDD by a correspondence rule such as the one using "age" etc. We describe the method, its current status and show some results for the TA experiment.

  12. Stereotactic hypofractionated accurate radiotherapy of the prostate (SHARP), 33.5 Gy in five fractions for localized disease: First clinical trial results

    SciTech Connect

    Madsen, Berit L. . E-mail: ronblm@vmmc.org; Hsi, R. Alex; Pham, Huong T.; Fowler, Jack F.; Esagui, Laura C.; Corman, John

    2007-03-15

    Purpose: To evaluate the feasibility and toxicity of stereotactic hypofractionated accurate radiotherapy (SHARP) for localized prostate cancer. Methods and Materials: A Phase I/II trial of SHARP performed for localized prostate cancer using 33.5 Gy in 5 fractions, calculated to be biologically equivalent to 78 Gy in 2 Gy fractions ({alpha}/{beta} ratio of 1.5 Gy). Noncoplanar conformal fields and daily stereotactic localization of implanted fiducials were used for treatment. Genitourinary (GU) and gastrointestinal (GI) toxicity were evaluated by American Urologic Association (AUA) score and Common Toxicity Criteria (CTC). Prostate-specific antigen (PSA) values and self-reported sexual function were recorded at specified follow-up intervals. Results: The study includes 40 patients. The median follow-up is 41 months (range, 21-60 months). Acute toxicity Grade 1-2 was 48.5% (GU) and 39% (GI); 1 acute Grade 3 GU toxicity. Late Grade 1-2 toxicity was 45% (GU) and 37% (GI). No late Grade 3 or higher toxicity was reported. Twenty-six patients reported potency before therapy; 6 (23%) have developed impotence. Median time to PSA nadir was 18 months with the majority of nadirs less than 1.0 ng/mL. The actuarial 48-month biochemical freedom from relapse is 70% for the American Society for Therapeutic Radiology and Oncology definition and 90% by the alternative nadir + 2 ng/mL failure definition. Conclusions: SHARP for localized prostate cancer is feasible with minimal acute or late toxicity. Dose escalation should be possible.

  13. Mean Polyp per Patient Is an Accurate and Readily Obtainable Surrogate for Adenoma Detection Rate: Results from an Opportunistic Screening Colonoscopy Program

    PubMed Central

    Delavari, Alireza; Salimzadeh, Hamideh; Bishehsari, Faraz; Sobh Rakhshankhah, Elham; Delavari, Farnaz; Moossavi, Shirin; Khosravi, Pejman; Nasseri-Moghaddam, Siavosh; Merat, Shahin; Ansari, Reza; Vahedi, Homayoon; Shahbazkhani, Bijan; Saberifiroozi, Mehdi; Sotoudeh, Masoud; Malekzadeh, Reza

    2015-01-01

    BACKGROUND The incidence of colorectal cancer is rising in several developing countries. In the absence of integrated endoscopy and pathology databases, adenoma detection rate (ADR), as a validated quality indicator of screening colonoscopy, is generally difficult to obtain in practice. We aimed to measure the correlation of polyp-related indicators with ADR in order to identify the most accurate surrogate(s) of ADR in routine practice. METHODS We retrospectively reviewed the endoscopic and histopathological findings of patients who underwent colonoscopy at a tertiary gastrointestinal clinic. The overall ADR and advanced-ADR were calculated using patient-level data. The Pearson’s correlation coefficient (r) was applied to measure the strength of the correlation between the quality metrics obtained by endoscopists. RESULTS A total of 713 asymptomatic adults aged 50 and older who underwent their first-time screening colonoscopy were included in this study. The ADR and advanced-ADR were 33.00% (95% CI: 29.52-36.54) and 13.18% (95% CI: 10.79-15.90), respectively. We observed good correlations between polyp detection rate (PDR) and ADR (r=0.93), and mean number of polyp per patient (MPP) and ADR (r=0.88) throughout the colon. There was a positive, yet insignificant correlation between advanced ADRs and non-advanced ADRs (r=0.42, p=0.35). CONCLUSION MPP is strongly correlated with ADR, and can be considered as a reliable and readily obtainable proxy for ADR in opportunistic screening colonoscopy programs. PMID:26609349

  14. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1993-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field has been conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a backswept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and in several cases provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  15. Experimental and computational results from a large low-speed centrifugal impeller

    NASA Technical Reports Server (NTRS)

    Hathaway, M. D.; Chriss, R. M.; Wood, J. R.; Strazisar, A. J.

    1994-01-01

    An experimental and computational investigation of the NASA Low-Speed Centrifugal Compressor (LSCC) flow field was conducted using laser anemometry and Dawes' 3D viscous code. The experimental configuration consists of a back-swept impeller followed by a vaneless diffuser. Measurements of the three-dimensional velocity field were acquired at several measurement planes through the compressor. The measurements describe both the throughflow and secondary velocity field along each measurement plane and, in several cases, provide details of the flow within the blade boundary layers. The experimental and computational results provide a clear understanding of the development of the throughflow momentum wake which is characteristic of centrifugal compressors.

  16. Experimental study of tilting-pad journal bearings - Comparison with theoretical thermoelastohydrodynamic results

    NASA Astrophysics Data System (ADS)

    Fillon, Michel; Bligoud, Jean-Claude; Frene, Jean

    1992-07-01

    Operating characteristics of four-shoe tilting-pad journal bearings of 100 mm diameter and 70 mm length are determined on an experimental device. The load, between pad configuration, varies from 0 to 10,000 N and the rotational speed is up to 4000 rpm. Forty thermocouples are used in order to measure bearing element temperatures (babbitt, shaft, housing and oil baths). The influence of operating conditions and preload ratio on bearing performances are studied. Comparison between theoretical and experimental results is presented. The theoretical model is also performed on a large tilting-pad journal bearing which was investigated experimentally by other authors.

  17. Optical scattering by biological aerosols: experimental and computational results on spore simulants

    NASA Astrophysics Data System (ADS)

    Sindoni, Orazio I.; Saija, Rosalba; Iatì, Maria Antonia; Borghese, Ferdinando; Denti, Paolo; Fernandes, Gustavo E.; Pan, Yong-Le; Chang, Richard K.

    2006-07-01

    We present both a computational and an experimental approach to the problem of biological aerosol characterization, joining the expertises reached in the field of theoretical optical scattering by complex, arbitrary shaped particles (multipole expansion of the electromagnetic fields and Transition Matrix), and a novel experimental technique based on two-dimensional angular optical scattering (TAOS). The good agreement between experimental and computational results, together with the possibility for a laboratory single-particle angle-resolved investigation, opens a new scenario in biological particle modelling, and might have major implications for a rapid discrimination of airborne particles.

  18. Experimental results on p (d) + A collisions at RHIC and the LHC

    NASA Astrophysics Data System (ADS)

    Sickles, Anne M.

    2014-11-01

    Recent experimental results at both the LHC and RHIC show evidence for hydrodynamic behavior in proton-nucleus and deuteron-nucleus collisions (p + A). This unexpected finding has prompted new measurements in p + A collisions in order to understand whether matter with similar properties is created in A + A and p + A collisions or whether another explanation is needed. In this proceedings, we will discuss the new experimental data and its interpretation within the context of heavy-ion collisions.

  19. Performance analysis of wick-assisted heat pipe solar collector and comparison with experimental results

    NASA Astrophysics Data System (ADS)

    Azad, E.

    2009-03-01

    The performance of heat pipe solar collector is investigated theoretically and experimentally. The system employs wick-assisted heat pipe for the heat transfer from the absorber (evaporator) to a heat exchanger (condenser). The heat pipe is made with a copper tube and the evaporator section is finned with aluminium plate. Theoretical model predicts the outlet water from heat exchanger, heat pipe temperature and also the thermal efficiency of solar collector. The results are compared with experimental data.

  20. Numerical simulation and experimental results of ultrasonic waves scattering on a model of the artery

    NASA Astrophysics Data System (ADS)

    Wojcik, J.; Powalowski, T.; Trawinski, Z.

    2008-02-01

    The aim of this paper is to compare the results of the mathematical modeling and experimental results of the ultrasonic waves scattering in the inhomogeneous dissipative medium. The research was carried out for an artery model (a pipe made of a latex), with internal diameter of 5 mm and wall thickness of 1.25 mm. The numerical solver was created for calculation of the fields of ultrasonic beams and scattered fields under different boundary conditions, different angles and transversal displacement of ultrasonic beams with respect to the position of the arterial wall. The investigations employed the VED ultrasonic apparatus. The good agreement between the numerical calculation and experimental results was obtained.

  1. Experimental results of a load management system for large commercial customers

    SciTech Connect

    Johnson, W.A.; Devaney, T.M.; Maher, A.M.

    1985-09-01

    Encouraging experimental results have been obtained from a two-way load management system for large commercial as well as governmental customers on the Potomac Electric Power Company (PEPCo) system. This paper presents these results and describes the inovative twoway load management system that was developed and installed to achieve them. The Robinton Products, Inc. system operates from a central processor located in PEPCO's control center and it communicates with the customer locations through a telephone system called ''Select-A-Station''. Future plans for the expansion of the system are presented along with experimental results.

  2. Experimental Results with Airfoils Tested in the High-speed Tunnel at Guidonia

    NASA Technical Reports Server (NTRS)

    Ferri, Antonio

    1940-01-01

    The results are presented of a triple series of tests using force measurements, pressure-distribution measurements, and air flow photographs on airfoil sections suitably selected so that comparison could be made between the experimental and theoretical results. The comparison with existing theory is followed by a discussion of the divergences found, and an attempt is made to find their explanation.

  3. Quantum reactive scattering in three dimensions using hyperspherical (APH) coordinates. IV. Discrete variable representation (DVR) basis functions and the analysis of accurate results for F+H2

    NASA Astrophysics Data System (ADS)

    Bačić, Z.; Kress, J. D.; Parker, G. A.; Pack, R. T.

    1990-02-01

    Accurate 3D coupled channel calculations for total angular momentum J=0 for the reaction F+H2→HF+H using a realistic potential energy surface are analyzed. The reactive scattering is formulated using the hyperspherical (APH) coordinates of Pack and Parker. The adiabatic basis functions are generated quite efficiently using the discrete variable representation method. Reaction probabilities for relative collision energies of up to 17.4 kcal/mol are presented. To aid in the interpretation of the resonances and quantum structure observed in the calculated reaction probabilities, we analyze the phases of the S matrix transition elements, Argand diagrams, time delays and eigenlifetimes of the collision lifetime matrix. Collinear (1D) and reduced dimensional 3D bending corrected rotating linear model (BCRLM) calculations are presented and compared with the accurate 3D calculations.

  4. Comparison of kinetic theory predictions with experimental results for a vibrated three-dimensional granular bed

    NASA Astrophysics Data System (ADS)

    Viswanathan, H.; Wildman, R. D.; Huntley, J. M.; Martin, T. W.

    2006-11-01

    The three-dimensional conservation equations relating energy and momentum transfer in a vibrated three-dimensional granular bed have been solved numerically by the finite element method. Two closures based on granular kinetic theory were used: one, the standard Fourier law relating heat flux to temperature gradient and the other, including an additional concentration gradient term. Each prediction of the two-dimensional axisymmetric granular temperature and packing fraction fields was compared against a one-dimensional model and three-dimensional experimental results, acquired using the technique of positron emission particle tracking. Both closures resulted in solutions that were in reasonable agreement with the experimental results, but it was found that differences between the predictions of each of the closures were relatively small in comparison to the anisotropy of the experimentally determined temperature distribution.

  5. Three-dimensional convection in horizontal cylinders - Numerical solutions and comparison with experimental and analytical results

    NASA Technical Reports Server (NTRS)

    Smutek, C.; Bontoux, P.; Roux, B.; Schiroky, G. H.; Hurford, A. C.

    1985-01-01

    The results of a three-dimensional numerical simulation of Boussinesq free convection in a horizontal differentially heated cylinder are presented. The computation was based on a Samarskii-Andreyev scheme (described by Leong, 1981) and a false-transient advancement in time, with vorticity, velocity, and temperature as dependent variables. Solutions for velocity and temperature distributions were obtained for Rayleigh numbers (based on the radius) Ra = 74-18,700, thus covering the core- and boundary-layer-driven regimes. Numerical solutions are compared with asymptotic analytical solutions and experimental data. The numerical results well represent the complex three-dimensional flows found experimentally.

  6. Preliminary Experimental Results on Controlled Cardiac Computed Tomography: A Phantom Study

    PubMed Central

    Lu, Yang; Cai, Zhijun; Wang, Ge; Zhao, Jun; Bai, Er-Wei

    2010-01-01

    In this paper, we present the preliminary experimental results on controlled cardiac computed tomography (CT), which aims to reduce the motion artifacts by means of controlling the x-ray source rotation speed. An innovative cardiac phantom enables us to perform this experiment without modifying the scanner. It is the first experiment on the cardiac CT with speed controlled x-ray source. Experimental results demonstrate that the proposed method successfully separates the phantom images at different phases (improve the temporal resolution) though controlling the x-ray speed. PMID:19696470

  7. Parametric Evaluation of Absorption Losses and Comparison of Numerical Results to Boeing 707 Aircraft Experimental HIRF Results

    NASA Astrophysics Data System (ADS)

    Kitaygorsky, J.; Amburgey, C.; Elliott, J. R.; Fisher, R.; Perala, R. A.

    A broadband (100 MHz-1.2 GHz) plane wave electric field source was used to evaluate electric field penetration inside a simplified Boeing 707 aircraft model with a finite-difference time-domain (FDTD) method using EMA3D. The role of absorption losses inside the simplified aircraft was investigated. It was found that, in this frequency range, none of the cavities inside the Boeing 707 model are truly reverberant when frequency stirring is applied, and a purely statistical electromagnetics approach cannot be used to predict or analyze the field penetration or shielding effectiveness (SE). Thus it was our goal to attempt to understand the nature of losses in such a quasi-statistical environment by adding various numbers of absorbing objects inside the simplified aircraft and evaluating the SE, decay-time constant τ, and quality factor Q. We then compare our numerical results with experimental results obtained by D. Mark Johnson et al. on a decommissioned Boeing 707 aircraft.

  8. Comparison of energy deposition calculations by the LAHET Code System with experimental results

    SciTech Connect

    Beard, C.A.; Lisowski, P.W.; Russell, G.J.; Waters, L.S.

    1993-08-01

    A comparison was performed between the energy deposition predicted by the LAHET Code System (LCS) with experimental values determined by Belyakov-Bodin et al. for 800, 1000, and 1200 MeV protons on targets composed of lead, bismuth, beryllium, carbon, and aluminum. The lead and bismuth showed agreement within approximately 10% at locations throughout the targets, and the agreement of the total energy deposited over the axial length of the targets ranged from 1% to 25%. For the lead and bismuth cases, the LCS predictions were always greater than the experimental results. For the lighter materials, the agreement at locations throughout the target only agreed within approximately 20%. No definable trend could be determined for the lighter materials since some LCS predictions were greater than the experimental results, some were less than the experimental results, and some showed very good agreement. The total energy deposited over the axial length of the targets was not compared for the lighter materials since it was not explicitly given with the experimental data.

  9. Statistical analysis of accurate prediction of local atmospheric optical attenuation with a new model according to weather together with beam wandering compensation system: a season-wise experimental investigation

    NASA Astrophysics Data System (ADS)

    Arockia Bazil Raj, A.; Padmavathi, S.

    2016-07-01

    Atmospheric parameters strongly affect the performance of Free Space Optical Communication (FSOC) system when the optical wave is propagating through the inhomogeneous turbulent medium. Developing a model to get an accurate prediction of optical attenuation according to meteorological parameters becomes significant to understand the behaviour of FSOC channel during different seasons. A dedicated free space optical link experimental set-up is developed for the range of 0.5 km at an altitude of 15.25 m. The diurnal profile of received power and corresponding meteorological parameters are continuously measured using the developed optoelectronic assembly and weather station, respectively, and stored in a data logging computer. Measured meteorological parameters (as input factors) and optical attenuation (as response factor) of size [177147 × 4] are used for linear regression analysis and to design the mathematical model that is more suitable to predict the atmospheric optical attenuation at our test field. A model that exhibits the R2 value of 98.76% and average percentage deviation of 1.59% is considered for practical implementation. The prediction accuracy of the proposed model is investigated along with the comparative results obtained from some of the existing models in terms of Root Mean Square Error (RMSE) during different local seasons in one-year period. The average RMSE value of 0.043-dB/km is obtained in the longer range dynamic of meteorological parameters variations.

  10. Experimental and computational results from the NASA Lewis low-speed centrifugal impeller at design and part-flow conditions

    SciTech Connect

    Chriss, R.M.; Wood, J.R.; Hathaway, M.D.

    1996-01-01

    The NASA Lewis Low-Speed Centrifugal Compressor (LSCC) has been investigated with laser anemometry and computational analysis at two flow conditions: the design condition as well as a lower mass flow condition. Previously reported experimental and computational results at the design condition are in the literature (Hathaway et al., 1993). In that paper extensive analysis showed that inducer blade boundary layers are centrifuged outward and entrained into the tip clearance flow and hence contribute significantly to the throughflow wake. In this report results are presented for a lower mass flow condition along with further results from the design case. The data set contained herein consists of three-dimensional laser velocimeter results upstream, inside, and downstream of the impeller. In many locations data have been obtained in the blade and endwall boundary layers. The data are presented in the form of throughflow velocity contours as well as secondary flow vectors. The results reported herein illustrate the effects of flow rate on the development of the throughflow momentum wake as well as on the secondary flow. The computational results presented confirm the ability of modern computational tools to model the complex flow in a subsonic centrifugal compressor accurately. However, the blade tip shape and tip clearance must be known in order to properly simulate the flow physics. In addition, the ability to predict changes in the throughflow wake, which is largely fed by the tip clearance flow, as the impeller is throttled should give designers much better confidence in using computational tools to improve impeller performance.

  11. Photon Detection with Cooled Avalanche Photodiodes: Theory and Preliminary Experimental Results

    NASA Technical Reports Server (NTRS)

    Robinson, D. L.; Hays, D. A.

    1985-01-01

    Avalanche photodiodes (APDs) can be operated in a geiger-tube mode so that they can respond to single electron events and thus be used as photon counting detectors. Operational characteristics and theory of APDs while used in this mode are analyzed and assessed. Preliminary experimental investigation of several commercially available APDs has commenced, and initial results for dark count statistics are presented.

  12. Solving System Of Linear Equations Using The Bimodal Optical Computer (Experimental Results)

    NASA Astrophysics Data System (ADS)

    Habli, M. A.; Abushagur, M. A. G.; Caulfield, H. J.

    1988-08-01

    Hardware and software design of the Bimodal Optical Computer (BOC) and its implementations are presented. Experimental results of the BOC for solving a system of linear equations Ax = b is reported. The effect of calibration, the convergence reliability of the BOC, and the convergence of problems with singular matrices are studied.

  13. An outcome-based learning model to identify emerging threats : experimental and simulation results.

    SciTech Connect

    Martinez-Moyano, I. J.; Conrad, S. H.; Andersen, D. F.; Decision and Information Sciences; SNL; Univ. at Albany

    2007-01-01

    The authors present experimental and simulation results of an outcome-based learning model as it applies to the identification of emerging threats. This model integrates judgment, decision making, and learning theories to provide an integrated framework for the behavioral study of emerging threats.

  14. At Odds: Reconciling Experimental and Theoretical Results in High School Physics

    ERIC Educational Resources Information Center

    Gates, Joshua

    2009-01-01

    For this experiment, students are divided into 2 groups and presented with a static equilibrium force-balance problem to solve. One group works entirely experimentally and the other group theoretically, using Newton's laws. The groups present their seemingly dissimilar results and must reconcile them through discussion. (Contains 3 figures.)

  15. Design and Experimental Results for a Natural-Laminar-Flow Airfoil for General Aviation Applications

    NASA Technical Reports Server (NTRS)

    Somers, D. M.

    1981-01-01

    A natural-laminar-flow airfoil for general aviation applications, the NLF(1)-0416, was designed and analyzed theoretically and verified experimentally in the Langley Low-Turbulence Pressure Tunnel. The basic objective of combining the high maximum lift of the NASA low-speed airfoils with the low cruise drag of the NACA 6-series airfoils was achieved. The safety requirement that the maximum lift coefficient not be significantly affected with transition fixed near the leading edge was also met. Comparisons of the theoretical and experimental results show excellent agreement. Comparisons with other airfoils, both laminar flow and turbulent flow, confirm the achievement of the basic objective.

  16. Non-destructive evaluation of metal-to-metal adhesive joints using vibration analysis: experimental results

    NASA Astrophysics Data System (ADS)

    Pandurangan, Pradeep; Buckner, Gregory D.

    2006-03-01

    Vibration based non-destructive evaluation shows promise for damage detection in metal-to-metal adhesive joints. This research investigates an experimental technique to diagnose damage in single-lap adhesive joints subject to cyclical tensile loading. Vibration analysis reveals that damage can be correlated with changes in identified modal damping ratios. Constant amplitude forcing functions are employed to eliminate amplitude-dependent nonlinearities in the dynamic response profiles. Damping estimates obtained from time-domain analyses correlate well with damage magnitudes. Finite element modal analysis of the lap joints supports the experimental results.

  17. Experimental results concerning global observables from the CERN SPS heavy ion program

    SciTech Connect

    Young, G.R.

    1990-06-01

    A brief overview is given of experimental results obtained during the initial operation of the heavy-ion program at the CERN SPS during the period 1986--1988. This paper confines itself to a presentation of results on so-called global observables, such as energy flow and multiplicity distributions, and on information extracted from them. Of particular interest among the latter are an estimate of the magnitude and spatial distribution of the energy density attained. 3 refs., 27 figs.

  18. Applying computational methods to interpret experimental results in tribology and enantioselective catalysis

    NASA Astrophysics Data System (ADS)

    Garvey, Michael T.

    Computational methods are rapidly becoming a mainstay in the field of chemistry. Advances in computational methods (both theory and implementation), increasing availability of computational resources and the advancement of parallel computing are some of the major forces driving this trend. It is now possible to perform density functional theory (DFT) calculations with chemical accuracy for model systems that can be interrogated experimentally. This allows computational methods to supplement or complement experimental methods. There are even cases where DFT calculations can give insight into processes and interactions that cannot be interrogated directly by current experimental methods. This work presents several examples of the application of computational methods to the interpretation and analysis of experimentally obtained results. First, triobological systems were investigated primarily with full-potential linearized augmented plane wave (FLAPW) method DFT calculations. Second, small organic molecules adsorbed on Pd(111) were studied using projector-augmented wave (PAW) method DFT calculations and scanning tunneling microscopy (STM) image simulations to investigate molecular interactions involved in enantioselective heterogeneous catalysis. A method for method for calculating pressure-dependent shear properties of model boundary-layer lubricants is demonstrated. The calculated values are compared with experimentally obtained results. For the case of methyl pyruvate adsorbed on Pd(111), DFT-calculated adsorption energies and structures are used along with STM simulations to identify species observed by STM imaging. A previously unobserved enol species is discovered to be present along with the expected keto species. The information about methyl pyruvate species on Pd(111) is combined with previously published studies of S-alpha-(1-naphthyl)-ethylamine (NEA) to understand the nature of their interaction upon coadsorption on Pd(111). DFT calculated structures and

  19. Oxygen-enriched diesel engine performance: A comparison of analytical and experimental results

    SciTech Connect

    Sekar, R.R.; Marr, W.W.; Cole, R.L.; Marciniak, T.J. ); Assanis, D.N. ); Schaus, J.E. )

    1990-01-01

    Use of oxygen-enriched combustion air in diesel engines can lead to significant improvements in power density, as well as reductions in particulate emissions, but at the expense of higher NO{sub x} emissions. Oxygen enrichment would also lead to lower ignition delays and the opportunity to burn lower grade fuels. Analytical and experimental studies are being conducted in parallel to establish the optimal combination of oxygen level and diesel fuel properties. In this paper, cylinder pressure data acquired on a single-cylinder engine are used to generate heat release rates for operation under various oxygen contents. These derived heat release rates are in turn used to improve the combustion correlation -- and thus the prediction capability -- of the simulation code. It is shown that simulated and measured cylinder pressures and other performance parameters are in good agreement. The improved simulation can provide sufficiently accurate predictions of trends and magnitudes to be useful in parametric studies assessing the effects of oxygen enrichment and water injection on diesel engine performance. Measured ignition delays, NO{sub x} emissions, and particulate emissions are also compared with previously published data. The measured ignition delays are slightly lower than previously reported. Particulate emissions measured in this series of tests are significantly lower than previously reported. 14 refs., 10 figs., 1 tab.

  20. Lateral resonances in 1{endash}3 piezoelectric periodic composite: Modeling and experimental results

    SciTech Connect

    Certon, D.; Patat, F.; Levassort, F.; Feuillard, G.; Karlsson, B.

    1997-04-01

    The objective of this work is to provide an accurate model of the lateral resonance modes in 1{endash}3 piezoelectric composite materials. These materials are widely used in ultrasonic transducers and the lowest lateral mode frequency gives the upper limit for the usable transducer bandwidth. Considering the propagation of purely transverse waves in a 2-D periodic medium of infinite thickness, two different approaches for obtaining the solutions are presented and compared. The first approach is based on the use of the Bloch waves theory. The second is a straightforward method (a so-called membrane method) which consists in numerically solving the propagation equation in the two-phase medium while taking into account the periodic boundary conditions. Methods based on both models are described that allow the calculation of the dispersion curves and the stop band limits, as well as the frequencies and the displacement fields of the lateral modes. A test case is used to compare and discuss the theoretical predictions provided by each model. The calculations of the first lateral mode frequency are compared with experimental values obtained for samples with different ceramic volume fractions. The conclusion reached indicates that the infinite thickness assumption is valid for plates of practical interest and that the membrane model enables the prediction of lateral mode frequency with low computation effort and an accuracy better than 5{percent}. {copyright} {ital 1997 Acoustical Society of America.}

  1. Crystal growth of pure substances: Phase-field simulations in comparison with analytical and experimental results

    NASA Astrophysics Data System (ADS)

    Nestler, B.; Danilov, D.; Galenko, P.

    2005-07-01

    A phase-field model for non-isothermal solidification in multicomponent systems [SIAM J. Appl. Math. 64 (3) (2004) 775-799] consistent with the formalism of classic irreversible thermodynamics is used for numerical simulations of crystal growth in a pure material. The relation of this approach to the phase-field model by Bragard et al. [Interface Science 10 (2-3) (2002) 121-136] is discussed. 2D and 3D simulations of dendritic structures are compared with the analytical predictions of the Brener theory [Journal of Crystal Growth 99 (1990) 165-170] and with recent experimental measurements of solidification in pure nickel [Proceedings of the TMS Annual Meeting, March 14-18, 2004, pp. 277-288; European Physical Journal B, submitted for publication]. 3D morphology transitions are obtained for variations in surface energy and kinetic anisotropies at different undercoolings. In computations, we investigate the convergence behaviour of a standard phase-field model and of its thin interface extension at different undercoolings and at different ratios between the diffuse interface thickness and the atomistic capillary length. The influence of the grid anisotropy is accurately analyzed for a finite difference method and for an adaptive finite element method in comparison.

  2. Predictions of the equation of state of cerium yield interesting insights into experimental results

    SciTech Connect

    Cherne, Frank J; Jensen, Brian J; Rigg, Paulo A; Elkin, Vyacheslav M

    2009-01-01

    There has been much interest in the past in understanding the dynamic properties of phase changing materials. In this paper we begin to explore the dynamic properties of the complex material of cerium. Cerium metal is a good candidate material to explore capabilities in determining a dynamic phase diagram on account of its low dynamic phase boundaries, namely, the {gamma}-{alpha}, and {alpha}-liquid phase boundaries. Here we present a combination of experimental results with calculated results to try to understand the dynamic behavior of the material. Using the front surface impact technique, we performed a series of experiments which displayed a rarefaction shock upon release. These experiments show that the reversion shock stresses occur at different magnitudes, allowing us to plot out the {gamma}-{alpha} phase boundary. Applying a multiphase equation of state a broader understanding of the experimental results will be discussed.

  3. Propagation effects for land mobile satellite systems: Overview of experimental and modeling results

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius; Vogel, Wolfhard J.

    1992-01-01

    Models developed and experiments performed to characterize the propagation environment associated with land mobile communication using satellites are discussed. Experiments were carried out with transmitters on stratospheric balloons, remotely piloted aircraft, helicopters, and geostationary satellites. This text is comprised of compiled experimental results for the expressed use of communications engineers, designers of planned Land Mobile Satellite Systems (LMSS), and modelers of propagation effects. The results presented here are mostly derived from systematic studies of propagation effects for LMSS geometries in the United States associated with rural and suburban regions. Where applicable, the authors also draw liberally from the results of other related investigations in Canada, Europe, and Australia. Frequencies near 1500 MHz are emphasized to coincide with frequency bands allocated for LMSS by the International Telecommunication Union, although earlier experimental work at 870 MHz is also included.

  4. IFNAR signaling directly modulates T lymphocyte activity, resulting in milder experimental autoimmune encephalomyelitis development.

    PubMed

    Kavrochorianou, Nadia; Evangelidou, Maria; Markogiannaki, Melina; Tovey, Michael; Thyphronitis, George; Haralambous, Sylva

    2016-01-01

    Although interferon-β is used as first-line therapy for multiple sclerosis, the cell type-specific activity of type I interferons in multiple sclerosis and its animal model, experimental autoimmune encephalomyelitis, remains obscure. In this study, we have elucidated the in vivo immunomodulatory role of type I interferon signaling in T cells during experimental autoimmune encephalomyelitis by use of a novel transgenic mouse, carrying a cd2-ifnar1 transgene on a interferon-α/β receptor 1 null genetic background, thus allowing expression of the interferon-α/β receptor 1 and hence, a functional type I interferon receptor exclusively on T cells. These transgenic mice exhibited milder experimental autoimmune encephalomyelitis with reduced T cell infiltration, demyelination, and axonal damage in the central nervous system. It is noteworthy that interferon-β administration in transgenic mice generated a more pronounced, protective effect against experimental autoimmune encephalomyelitis compared with untreated littermates. In vivo studies demonstrated that before experimental autoimmune encephalomyelitis onset, endogenous type I interferon receptor signaling in T cells led to impaired T-helper 17 responses, with a reduced fraction of CCR6(+) CD4(+) T cells in the periphery. At the acute phase, an increased proportion of interleukin-10- and interferon-γ-producing CD4(+) T cells was detected in the periphery of the transgenic mice, accompanied by up-regulation of the interferon-γ-induced gene Irgm1 in peripheral T cells. Together, these results reveal a hitherto unknown T cell-associated protective role of type I interferon in experimental autoimmune encephalomyelitis that may provide valuable clues for designing novel therapeutic strategies for multiple sclerosis. PMID:26232452

  5. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  6. Advanced Supersonic Nozzle Concepts: Experimental Flow Visualization Results Paired With LES

    NASA Astrophysics Data System (ADS)

    Berry, Matthew; Magstadt, Andrew; Stack, Cory; Gaitonde, Datta; Glauser, Mark; Syracuse University Team; The Ohio State University Team

    2015-11-01

    Advanced supersonic nozzle concepts are currently under investigation, utilizing multiple bypass streams and airframe integration to bolster performance and efficiency. This work focuses on the parametric study of a supersonic, multi-stream jet with aft deck. The single plane of symmetry, rectangular nozzle, displays very complex and unique flow characteristics. Flow visualization techniques in the form of PIV and schlieren capture flow features at various deck lengths and Mach numbers. LES is compared to the experimental results to both validate the computational model and identify limitations of the simulation. By comparing experimental results to LES, this study will help create a foundation of knowledge for advanced nozzle designs in future aircraft. SBIR Phase II with Spectral Energies, LLC under direction of Barry Kiel.

  7. Parallel Path Magnet Motor: Development of the Theoretical Model and Analysis of Experimental Results

    NASA Astrophysics Data System (ADS)

    Dirba, I.; Kleperis, J.

    2011-01-01

    Analytical and numerical modelling is performed for the linear actuator of a parallel path magnet motor. In the model based on finite-element analysis, the 3D problem is reduced to a 2D problem, which is sufficiently precise in a design aspect and allows modelling the principle of a parallel path motor. The paper also describes a relevant numerical model and gives comparison with experimental results. The numerical model includes all geometrical and physical characteristics of the motor components. The magnetic flux density and magnetic force are simulated using FEMM 4.2 software. An experimental model has also been developed and verified for the core of switchable magnetic flux linear actuator and motor. The results of experiments are compared with those of theoretical/analytical and numerical modelling.

  8. Controls-structures interaction guest investigator program: Overview and phase 1 experimental results and future plans

    NASA Technical Reports Server (NTRS)

    Smith-Taylor, Rudeen; Tanner, Sharon E.

    1993-01-01

    The NASA Controls-Structures Interaction (CSI) Guest Investigator program is described in terms of its support of the development of CSI technologies. The program is based on the introduction of CSI researchers from industry and academia to available test facilities for experimental validation of technologies and methods. Phase 1 experimental results are reviewed with attention given to their use of the Mini-MAST test facility and the facility for the Advance Control Evaluation of Structures. Experiments were conducted regarding the following topics: collocated/noncollocated controllers, nonlinear math modeling, controller design, passive/active suspension systems design, and system identification and fault isolation. The results demonstrate that significantly enhanced performance from the control techniques can be achieved by integrating knowledge of the structural dynamics under consideration into the approaches.

  9. Experimental results of TDM/TDMA system via ETS-V

    NASA Astrophysics Data System (ADS)

    Sakasai, Makoto; Morikawa, Eihisa; Miura, Ryu; Arakaki, Yoshiya

    1992-07-01

    The Engineering Test Satellite-V (ETS-V) was launched in 1987, helping realize the Experimental Mobile Satellite System, where several types of mobile satellite communication experiments have been conducted. A simplified TDM/TDMA communication terminal equipment developed by the Communication Research Laboratory was used in ship experiments in the Pacific Ocean and South China Sea. This paper describes the data transmission, synchronization hold and initial acquisition characteristics resulting from these experiments.

  10. FIRST EXPERIMENTAL RESULTS FROM DEGAS, THE QUANTUM LIMITED BRIGHTNESS ELECTRON SOURCE

    SciTech Connect

    Zolotorev, Max S.; Commins, Eugene D.; Oneill, James; Sannibale, Fernando; Tremsin, Anton; Wan, Weishi

    2008-06-23

    The construction of DEGAS (DEGenerate Advanced Source), a proof of principle for a quantum limited brightness electron source, has been completed at the Lawrence Berkeley National Laboratory. The commissioning and the characterization of this source, designed to generate coherent single electron 'bunches' with brightness approaching the quantum limit at a repetition rate of few MHz, has been started. In this paper the first experimental results are described.

  11. Columbus meteoroid/debris protection study - Experimental simulation techniques and results

    NASA Astrophysics Data System (ADS)

    Schneider, E.; Kitta, K.; Stilp, A.; Lambert, M.; Reimerdes, H. G.

    1992-08-01

    The methods and measurement techniques used in experimental simulations of micrometeoroid and space debris impacts with the ESA's laboratory module Columbus are described. Experiments were carried out at the two-stage light gas gun acceleration facilities of the Ernst-Mach Institute. Results are presented on simulations of normal impacts on bumper systems, oblique impacts on dual bumper systems, impacts into cooled targets, impacts into pressurized targets, and planar impacts of low-density projectiles.

  12. Experimental results on combined ultraviolet-proton excitation of moon rock luminescence.

    NASA Technical Reports Server (NTRS)

    Nash, D. B.

    1973-01-01

    The experimental results reported indicate that a small synergistic effect may exist between near-UV radiation and solar-wind-energy protons in solar radiation that could slightly enhance luminescence generation on the moon's surface. The magnitude of the effect, however, is far too small to account for the apparent orders-of-magnitude discrepancy between reported telescope measurements of lunar luminescence and the limitation of lunar luminescence intensity based on lab studies of moon rocks.

  13. Optimal SNR exposure time for speckle imaging: experimental results with frequency-dependent detector noise

    NASA Astrophysics Data System (ADS)

    Tyler, David W.; Suzuki, Andrew H.; von Bokern, Mark A.; Keating, Donna D.; Roggemann, Michael C.

    1994-06-01

    We review recent arguments for using increased spectral bandwidth and exposure times to optimize the signal-to-noise ratio of speckle imaging estimators and discuss the tradeoff between camera exposure time and the number of data frames collected when observing time is fixed. We compare experimental results with a previously-derived expression for optimal exposure time and find reasonable agreement after accounting for frequency-dependent camera noise.

  14. A digital computer propulsion control facility: Description of capabilities and summary of experimental program results

    NASA Technical Reports Server (NTRS)

    Zeller, J. R.; Arpasi, D. J.; Lehtinen, B.

    1976-01-01

    Flight weight digital computers are being used today to carry out many of the propulsion system control functions previously delegated exclusively to hydromechanical controllers. An operational digital computer facility for propulsion control mode studies has been used successfully in several experimental programs. This paper describes the system and some of the results concerned with engine control, inlet control, and inlet engine integrated control. Analytical designs for the digital propulsion control modes include both classical and modern/optimal techniques.

  15. Flow reference method testing and analysis: Wind tunnel experimental results. Volume 1

    SciTech Connect

    1997-02-01

    This report describes the results of wind tunnel tests that the US Environmental Protection Agency (EPA) conducted in 1997 as part of a major study to evaluate potential improvements to Method 2, EPA`s test method for measuring flue gas volumetric flow in stacks. Conducted in the Merrill Subsonic Wind Tunnel at North Carolina State University in Raleigh, the wind tunnel tests were designed to evaluate how accurately various probes can measure angles and velocity of flow under prescribed conditions and, additionally, to calibrate the probes for use in planned field experiments. To provide a basis for selecting probes for subsequent field tests, the wind tunnel testing was performed over a range of velocity, pitch, and yaw angle settings approximating the conditions encountered at actual utility sites.

  16. Flow Around a Complex Building: Comparisons Between Experimental and Modeled Results

    SciTech Connect

    Calhoun, R.J.; Chan, S.; Gouveia, F.; Lee, R.; Leone, J.; Shinn, J.; Stevens, D.

    1999-11-22

    The authors compare the results of computer simulated flow fields around building 170 (B170) at Lawrence Livermore National Laboratory (LLNL) with field measurements. This is the first stage of a larger effort to assess the ability of computational fluid dynamics (CFD) models to predict atmospheric dispersion scenarios around building complexes. At this stage, the focus is on accurate simulation of the velocity field. Two types of simulations were performed: predictive and post-experiment. The purpose of the predictive runs was primarily to provide initial guidance for the planning of the experiment. By developing an approximate understanding of the major features of the flow field, they were able to more effectively deploy the sensors.

  17. Characterisation and optimisation of flexible transfer lines for liquid helium. Part I: Experimental results

    NASA Astrophysics Data System (ADS)

    Dittmar, N.; Haberstroh, Ch.; Hesse, U.; Krzyzowski, M.

    2016-04-01

    The transfer of liquid helium (LHe) into mobile dewars or transport vessels is a common and unavoidable process at LHe decant stations. During this transfer reasonable amounts of LHe evaporate due to heat leak and pressure drop. Thus generated helium gas needs to be collected and reliquefied which requires a huge amount of electrical energy. Therefore, the design of transfer lines used at LHe decant stations has been optimised to establish a LHe transfer with minor evaporation losses which increases the overall efficiency and capacity of LHe decant stations. This paper presents the experimental results achieved during the thermohydraulic optimisation of a flexible LHe transfer line. An extensive measurement campaign with a set of dedicated transfer lines equipped with pressure and temperature sensors led to unique experimental data of this specific transfer process. The experimental results cover the heat leak, the pressure drop, the transfer rate, the outlet quality, and the cool-down and warm-up behaviour of the examined transfer lines. Based on the obtained results the design of the considered flexible transfer line has been optimised, featuring reduced heat leak and pressure drop.

  18. Estimating the hyperfine coupling parameters of the avian compass by comprehensively considering the available experimental results.

    PubMed

    Xu, Bao-Ming; Zou, Jian; Li, Jun-Gang; Shao, Bin

    2013-09-01

    Migratory birds can utilize the geomagnetic field for orientation and navigation through a widely accepted radical-pair mechanism. Although many theoretical works have been done, the available experimental results have not been fully considered, especially the temporary disorientation induced by the field which is increased by 30% of the geomagnetic field and the disorientation of the very weak resonant field of 15 nT. In this paper, we consider the monotonicity of the singlet yield angular profile as the prerequisite of direction sensitivity, and find that for some optimal values of the hyperfine coupling parameters (that is, the order of 10^{-7}∼10^{-6} meV) the experimental results available so far can be satisfied. We also investigate the effects of two decoherence environments and demonstrate that, in order to satisfy the available experimental results, the decoherence rate should be lower than the recombination rate. Finally, we investigate the effects of the fluctuating magnetic noises and find that the vertical noise destroys the monotonicity of the profile completely, but the parallel noise preserves the monotonicity perfectly and even can enhance the direction sensitivity. PMID:24125290

  19. Experimental results for a 1.5 MW, 110 GHz gyrotron oscillator with reduced mode competition

    SciTech Connect

    Choi, E.M.; Marchewka, C.D.; Mastovsky, I.; Sirigiri, J.R.; Shapiro, M.A.; Temkin, R.J.

    2006-02-15

    A new result from a 110 GHz gyrotron at MIT is reported with an output power of 1.67 MW and an efficiency of 42% when operated at 97 kV and 41 A for 3 {mu}s pulses in the TE{sub 22,6} mode. These results are a major improvement over results obtained with an earlier cavity design, which produced 1.43 MW of power at 37% efficiency. These new results were obtained using a cavity with a reduced output taper angle and a lower ohmic loss when compared with the earlier cavity. The improved operation is shown experimentally to be the result of reduced mode competition from the nearby TE{sub 19,7} mode. The reduced mode competition agrees well with an analysis of the startup scenario based on starting current simulations. The present results should prove useful in planning long pulse and CW versions of the 110 GHz gyrotron.

  20. Summary of experimental heat-transfer results from the turbine hot section facility

    NASA Astrophysics Data System (ADS)

    Gladden, Herbert J.; Yeh, Fredrick C.

    1993-04-01

    Experimental data from the turbine Hot Section Facility are presented and discussed. These data include full-coverage film-cooled airfoil results as well as special instrumentation results obtained at simulated real engine conditions. Local measurements of airfoil wall temperature, airfoil gas-path static-pressure distribution, and local heat-transfer coefficient distributions are presented and discussed. In addition, measured gas and coolant temperatures and pressures are presented. These data are also compared with analyses from Euler and boundary-layer codes.

  1. Comparison of Finite Element Non-Linear Beam Random Response with Experimental Results

    NASA Astrophysics Data System (ADS)

    Chen, R. R.; Mei, C.; Wolfe, HF

    1996-09-01

    A finite element formulation combined with the equivalent linearization technique and normal mode method is developed for the non-linear random response of beams subjected to acoustic and thermal loads applied simultaneously. To validate the present formulation and solution procedure, results are compared with the classical continuum solution and the Fokker-Planck-Kolmogorov equation solution. Comparison is also made with experimental data for a pre-stretched clamped beam. Random responses of thermally buckled simply supported beam, clamped beam and simply supported-clamped beam are presented. The comparison of the present simultaneously loaded response with the existing sequentially loaded results shows a significant difference between them.

  2. Studies of Multipactor in Dielectric-Loaded Accelerator Structures: Comparison of Simulation Results with Experimental Data

    SciTech Connect

    Sinitsyn, Oleksandr; Nusinovich, Gregory; Antonsen, Thomas Jr.

    2010-11-04

    In this paper new results of numerical studies of multipactor in dielectric-loaded accelerator structures are presented. The results are compared with experimental data obtained during recent studies of such structures performed by Argonne National Laboratory, the Naval Research Laboratory, SLAC National Accelerator Laboratory and Euclid TechLabs, LLC. Good agreement between the theory and experiment was observed for the structures with larger inner diameter, however the structures with smaller inner diameter demonstrated a discrepancy between the two. Possible reasons for such discrepancy are discussed.

  3. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, T.; Sholes, J. E.

    1975-01-01

    The preliminary results of two projects in the development phase of reliable wind turbines designed to supply cost-competitive electrical energy were discussed. An experimental 100 kW wind turbine design and its status are first reviewed. The results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs are also discussed. These studies predict wind energy costs of 1.5 to 7 cents per kW-h for wind turbines produced in quantities of 100 to 1000 per year and located at sites having average winds of 12 to 18 mph.

  4. The 3D structure of the hadrons: recents results and experimental program at Jefferson Lab

    SciTech Connect

    Munoz Camacho, Carlos

    2014-04-01

    The understanding of Quantum Chromodynamics (QCD) at large distances still remains one of the main outstanding problems of nuclear physics. Studying the internal structure of hadrons provides a way to probe QCD in the non-perturbative domain and can help us unravel the internal structure of the most elementary blocks of matter. Jefferson Lab (JLab) has already delivered results on how elementary quarks and gluons create nucleon structure and properties. The upgrade of JLab to 12 GeV will allow the full exploration of the valence-quark structure of nucleons and the extraction of real threedimensional pictures. I will present recent results and review the future experimental program at JLab.

  5. A three-phase series-parallel resonant converter -- analysis, design, simulation and experimental results

    SciTech Connect

    Bhat, A.K.S.; Zheng, L.

    1995-12-31

    A three-phase dc-to-dc series-parallel resonant converter is proposed and its operating modes for 180{degree} wide gating pulse scheme are explained. A detailed analysis of the converter using constant current model and Fourier series approach is presented. Based on the analysis, design curves are obtained and a design example of 1 kW converter is given. SPICE simulation results for the designed converter and experimental results for a 500 W converter are presented to verify the performance of the proposed converter for varying load conditions. The converter operates in lagging PF mode for the entire load range and requires a narrow variation in switching frequency.

  6. Experimental Results of NWCF Run H4 Calcine Dissolution Studies Performed in FY-98 and -99

    SciTech Connect

    Garn, Troy Gerry; Herbst, Ronald Scott; Batcheller, Thomas Aquinas; Sierra, Tracy Laureena

    2001-08-01

    Dissolution experiments were performed on actual samples of NWCF Run H-4 radioactive calcine in fiscal years 1998 and 1999. Run H-4 is an aluminum/sodium blend calcine. Typical dissolution data indicates that between 90-95 wt% of H-4 calcine can be dissolved using 1gram of calcine per 10 mLs of 5-8M nitric acid at boiling temperature. Two liquid raffinate solutions composed of a WM-188/aluminum nitrate blend and a WM-185/aluminum nitrate blend were converted into calcine at the NWCF. Calcine made from each blend was collected and transferred to RAL for dissolution studies. The WM-188/aluminum nitrate blend calcine was dissolved with resultant solutions used as feed material for separation treatment experimentation. The WM-185/aluminum nitrate blend calcine dissolution testing was performed to determine compositional analyses of the dissolved solution and generate UDS for solid/liquid separation experiments. Analytical fusion techniques were then used to determine compositions of the solid calcine and UDS from dissolution. The results from each of these analyses were used to calculate elemental material balances around the dissolution process, validating the experimental data. This report contains all experimental data from dissolution experiments performed using both calcine blends.

  7. Wind Code Application to External Forebody Flowfields with Comparisons to Experimental Results

    NASA Technical Reports Server (NTRS)

    Frate, F. C.; Kim, H. D.

    2001-01-01

    The WIND Code, a general purpose Navier-Stokes solver, has been utilized to obtain supersonic external flowfield Computational Fluid Dynamics (CFD) solutions over an axisymmetric, parabolic forebody with comparisons made to wind tunnel experimental results. Various cases have been investigated at supersonic freestream conditions ranging from Mach 2.0 to 3.5, at 0 deg and 3 deg angles-of-attack, and with either a sharp-nose or blunt-nose forebody configuration. Both a turbulent (Baldwin-Lomax algebraic turbulence model) and a laminar model have been implemented in the CFD. Obtaining the solutions involved utilizing either the parabolized- or full-Navier-Stokes analyses supplied in WIND. Comparisons have been made with static pressure measurements, with boundary-layer rake and flowfield rake pitot pressure measurements, and with temperature sensitive paint experimental results. Using WIND's parabolized Navier-Stokes capability, grid sequencing, and the Baldwin-Lomax algebraic turbulence model allowed for significant reductions in computational time while still providing good agreement with experiment. Given that CFD and experiment compare well, WIND is found to be a good computational platform for solving this type of forebody problem, and the grids developed in conjunction with it will be used in the future to investigate varying freestream conditions not tested experimentally.

  8. Respiratory rate detection algorithm based on RGB-D camera: theoretical background and experimental results.

    PubMed

    Benetazzo, Flavia; Freddi, Alessandro; Monteriù, Andrea; Longhi, Sauro

    2014-09-01

    Both the theoretical background and the experimental results of an algorithm developed to perform human respiratory rate measurements without any physical contact are presented. Based on depth image sensing techniques, the respiratory rate is derived by measuring morphological changes of the chest wall. The algorithm identifies the human chest, computes its distance from the camera and compares this value with the instantaneous distance, discerning if it is due to the respiratory act or due to a limited movement of the person being monitored. To experimentally validate the proposed algorithm, the respiratory rate measurements coming from a spirometer were taken as a benchmark and compared with those estimated by the algorithm. Five tests were performed, with five different persons sat in front of the camera. The first test aimed to choose the suitable sampling frequency. The second test was conducted to compare the performances of the proposed system with respect to the gold standard in ideal conditions of light, orientation and clothing. The third, fourth and fifth tests evaluated the algorithm performances under different operating conditions. The experimental results showed that the system can correctly measure the respiratory rate, and it is a viable alternative to monitor the respiratory activity of a person without using invasive sensors. PMID:26609383

  9. Rapid, Nonmechanical, Damage-Free Figuring Of Optical Surfaces Using Plasma-Assisted Chemical Etching (PACE): Part I Experimental Results

    NASA Astrophysics Data System (ADS)

    Bollinger, L. D.; Zarowin, Charles B.

    1989-01-01

    We present experimental results of an ongoing investigation demonstrating that Plasma Assisted Chemical Etching (PACE) can rapidly and controllably figure and smooth optical surfaces without mechanical contact; thus, removing the constraints on the design of optical elements imposed by mechanical processes, and, allowing higher quality optical surfaces. This process employs a plasma etch process originally developed to pattern micro-electronic circuits by etching through a relatively non-erodable lithographically patterned mask. The PACE process shapes the optical surface by removing material in a small area under a confined reactive gas plasma moved over the surface. Rates of removal as high as 10 m per minute are obtainable with accurate control. The removal footprint can be varied during the process. PACE inherently smooths or polishes while removing material, exposing a virgin surface free of process generated contamination and subsurface damage. Although other materials can also be figured by a PACE process, for this study, apparatus and processes were developed to explore the figuring of fused silica. Results will be shown demonstrating: repeatability and control of removal rate and footprint; predictability of material removal with plasma "tool" motion; and smoothing.

  10. Artificial cochlea and acoustic black hole travelling waves observation: Model and experimental results

    NASA Astrophysics Data System (ADS)

    Foucaud, Simon; Michon, Guilhem; Gourinat, Yves; Pelat, Adrien; Gautier, François

    2014-07-01

    An inhomogeneous fluid structure waveguide reproducing passive behaviour of the inner ear is modelled with the help of the Wentzel-Kramers-Brillouin method. A physical setup is designed and built. Experimental results are compared with a good correlation to theoretical ones. The experimental setup is a varying width plate immersed in fluid and terminated with an acoustic black hole. The varying width plate provides a spatial repartition of the vibration depending on the excitation frequency. The acoustic black hole is made by decreasing the plate's thickness with a quadratic profile and by covering this region with a thin film of viscoelastic material. Such a termination attenuates the flexural wave reflection at the end of the waveguide, turning standing waves into travelling waves.

  11. Shuttle Return To Flight Experimental Results: Cavity Effects on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Horvath, Thomas J.; Berry, Scott A.

    2006-01-01

    The effect of an isolated rectangular cavity on hypersonic boundary layer transition of the windward surface of the Shuttle Orbiter has been experimentally examined in the Langley Aerothermodynamics Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for return to flight. This experimental study was initiated to provide a cavity effects database for developing hypersonic transition criteria to support on-orbit decisions to repair a damaged thermal protection system. Boundary layer transition results were obtained using 0.0075-scale Orbiter models with simulated tile damage (rectangular cavities) of varying length, width, and depth. The database contained within this report will be used to formulate cavity-induced transition correlations using predicted boundary layer edge parameters.

  12. Design and Experimental Results for the S825 Airfoil; Period of Performance: 1998-1999

    SciTech Connect

    Somers, D. M.

    2005-01-01

    A 17%-thick, natural-laminar-flow airfoil, the S825, for the 75% blade radial station of 20- to 40-meter, variable-speed and variable-pitch (toward feather), horizontal-axis wind turbines has been designed and analyzed theoretically and verified experimentally in the NASA Langley Low-Turbulence Pressure Tunnel. The two primary objectives of high maximum lift, relatively insensitive to roughness and low-profile drag have been achieved. The airfoil exhibits a rapid, trailing-edge stall, which does not meet the design goal of a docile stall. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results generally show good agreement.

  13. Radio propagation at 900 MHz in urban areas: Models with a fixed frequency and experimental results

    NASA Astrophysics Data System (ADS)

    Olivier, P.; Tiffon, J.

    1984-09-01

    Models which describe multipath propagation are examined in order to design a 900 MHz mobile communication system adapted to urban areas. A justification of the experimental data treatment is derived from this analysis. The measurements were made at a fixed 855 MHz frequency, transmitting from three locations. The fast fluctuations of the received signals are well represented by a Rayleigh process, which means that there are practically no paths of direct transmission. The coherence length is 1 m. The statistical distribution of the average field is Gaussian and the normal deviation decreases with the distance emitter-receiver. The empiric Okumura-Hata prediction model agrees well with the experimental results, giving an average cell field decreasing with distance with a logarithmic law.

  14. Shuttle Return To Flight Experimental Results: Protuberance Effects on Boundary Layer Transition

    NASA Technical Reports Server (NTRS)

    Liechty, Derek S.; Berry, Scott A.; Horvath, Thomas J.

    2006-01-01

    The effect of isolated roughness elements on the windward boundary layer of the Shuttle Orbiter has been experimentally examined in the Langley Aerothermodynamic Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for return to flight. This experimental effort was initiated to provide a roughness effects database for developing transition criteria to support on-orbit decisions to repair damage to the thermal protection system. Boundary layer transition results were obtained using trips of varying heights and locations along the centerline and attachment lines of 0.0075-scale models. Global heat transfer images using phosphor thermography of the Orbiter windward surface and the corresponding heating distributions were used to infer the state of the boundary layer (laminar, transitional, or turbulent). The database contained within this report will be used to formulate protuberance-induced transition correlations using predicted boundary layer edge parameters.

  15. Use of dynamic theory to describe experimental results from volume holography

    NASA Technical Reports Server (NTRS)

    Magnusson, R.; Gaylord, T. K.

    1976-01-01

    The general applicability of dynamic theory to the description of the recording and readout characteristics of volume (thick) hologram gratings is indicated. In dynamic theory (as opposed to static theory), the volume nature of the thick holographic grating allows the interference of an incident light beam with its own diffracted beam inside the recording medium. This effect causes the continuous recording of another grating that alters the initial one, producing a resultant grating that is not uniform through the thickness of the recording material and a grating whose writing and reading characteristics may vary dramatically, depending on the recording material and the experimental conditions. A large number of diverse types of writing, reading, and angular-selectivity behavior have been reported. The dynamic theory of thick-hologram writing and reading is shown to predict qualitatively all of these various types of experimental behavior.

  16. Design and Experimental Results for the S827 Airfoil; Period of Performance: 1998--1999

    SciTech Connect

    Somers, D. M.

    2005-01-01

    A 21%-thick, natural-laminar-flow airfoil, the S827, for the 75% blade radial station of 40- to 50-meter, stall-regulated, horizontal-axis wind turbines has been designed and analyzed theoretically and verified experimentally in the NASA Langley Low-Turbulence Pressure Tunnel. The primary objective of restrained maximum lift has not been achieved, although the maximum lift is relatively insensitive to roughness, which meets the design goal. The airfoil exhibits a relatively docile stall, which meets the design goal. The primary objective of low profile drag has been achieved. The constraints on the pitching moment and the airfoil thickness have been satisfied. Comparisons of the theoretical and experimental results generally show good agreement with the exception of maximum lift, which is significantly underpredicted.

  17. Stimulating Contributions to Public Goods through Information Feedback: Some Experimental Results

    PubMed Central

    Janssen, Marco A.; Lee, Allen; Sundaram, Hari

    2016-01-01

    In traditional public good experiments participants receive an endowment from the experimenter that can be invested in a public good or kept in a private account. In this paper we present an experimental environment where participants can invest time during five days to contribute to a public good. Participants can make contributions to a linear public good by logging into a web application and performing virtual actions. We compared four treatments, with different group sizes and information of (relative) performance of other groups. We find that information feedback about performance of other groups has a small positive effect if we control for various attributes of the groups. Moreover, we find a significant effect of the contributions of others in the group in the previous day on the number of points earned in the current day. Our results confirm that people participate more when participants in their group participate more, and are influenced by information about the relative performance of other groups. PMID:27459070

  18. Activity of "nonspecific pancreatic carboxylesterase" in rat serum in experimentally induced acute pancreatitis (preliminary results).

    PubMed

    Kálmán, A; Kálmán, Z; Velösy, G; Vargha, G; Vargha, G; Papp, M

    1989-01-01

    The aim of this study was to obtain more information on the serum level of "nonspecific pancreatic carboxylesterase" (PCE) in experimentally induced acute pancreatitis in rats. The effects of caerulein stimulation, hepatic duct ligation, bile-pancreatic duct ligation or the effect of retrograde injection of saline, 5% taurocholate and sunflower oil were investigated. The activity of PCE and amylase was measured in the serum, pancreatic tissue, pancreatic juice and ascitic fluid. The changes in PCE activity were greater (both in directions to increase or decrease) than that of amylase, produced by different experimental procedures. The results confirm the thesis that the serum activity of PCE is a more sensitive diagnostic method than that of amylase to detect the inflammatory process in the pancreas or the effect of obstruction of the pancreatic duct. PMID:2480696

  19. Circular Samples as Objects for Magnetic Resonance Imaging - Mathematical Simulation, Experimental Results

    NASA Astrophysics Data System (ADS)

    Frollo, Ivan; Krafčík, Andrej; Andris, Peter; Přibil, Jiří; Dermek, Tomáš

    2015-12-01

    Circular samples are the frequent objects of "in-vitro" investigation using imaging method based on magnetic resonance principles. The goal of our investigation is imaging of thin planar layers without using the slide selection procedure, thus only 2D imaging or imaging of selected layers of samples in circular vessels, eppendorf tubes,.. compulsorily using procedure "slide selection". In spite of that the standard imaging methods was used, some specificity arise when mathematical modeling of these procedure is introduced. In the paper several mathematical models were presented that were compared with real experimental results. Circular magnetic samples were placed into the homogenous magnetic field of a low field imager based on nuclear magnetic resonance. For experimental verification an MRI 0.178 Tesla ESAOTE Opera imager was used.

  20. Rotational knee strain resulting in patellar dislocation. An experimental study in rabbits.

    PubMed

    Finsterbush, A

    1982-09-01

    The right lower extremities of 64 young rabbits were immobilized by a plaster spica. The animals developed a gait pattern, which included internal tibial rotation and adduction of the left (unimmobilized) tibia. Twenty-one of the animals developed medial patellar dislocation in the unimmobilized lower extremity. The mechanism of the patellar dislocation in this experimental model was possibly overstretching of the lateral colateral ligament and the lateral side of the joint capsule, associated with medial rotation of the tibia and the tibial tubercle. The direction of patellar pull when gliding inferiorly during knee flexion was shifted medially, resulting in patellar dislocation and secondarily, in formation of an exostosis under the displaced patella. Hip arthrodesis in humans, as a course of rotational instability of the contralateral knee, resembles some aspects of this experimental condition. PMID:7105585

  1. LBE water interaction in sub-critical reactors: First experimental and modelling results

    NASA Astrophysics Data System (ADS)

    Ciampichetti, A.; Agostini, P.; Benamati, G.; Bandini, G.; Pellini, D.; Forgione, N.; Oriolo, F.; Ambrosini, W.

    2008-06-01

    This paper concerns the study of the phenomena involved in the interaction between LBE and pressurised water which could occur in some hypothetical accidents in accelerator driven system type reactors. The LIFUS 5 facility was designed and built at ENEA-Brasimone to reproduce this kind of interaction in a wide range of conditions. The first test of the experimental program was carried out injecting water at 70 bar and 235 °C in a reaction vessel containing LBE at 1 bar and 350 °C. A pressurisation up to 80 bar was observed in the test section during the considered transient. The SIMMER III code was used to simulate the performed test. The calculated data agree in a satisfactory way with the experimental results giving confidence in the possibility to use this code for safety analyses of heavy liquid metal cooled reactors.

  2. Supersonic Retropropulsion Experimental Results from the NASA Ames 9- x 7-Foot Supersonic Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Rhode, Matthew N.; Edquist, Karl T.

    2012-01-01

    Supersonic retropropulsion was experimentally examined in the Ames Research Center 9x7-Foot Supersonic Wind Tunnel at Mach 1.8 and 2.4. The experimental model, previously designed for and tested in the Langley Research Center Unitary Plan Wind Tunnel at Mach 2.4, 3.5 and 4.6, was a 5-in diameter 70-deg sphere-cone forebody with a 9.55-in long cylindrical aftbody. The forebody was designed to accommodate up to four 4:1 area ratio nozzles, one on the model centerline and the other three on the half radius spaced 120-deg apart. Surface pressure and flow visualization were the primary measurements, including high-speed data to investigate the dynamics of the interactions between the bow and nozzle shocks. Three blowing configurations were tested with thrust coefficients up to 10 and angles of attack up to 20-deg. Preliminary results and observations from the test are provided

  3. Crystalline and Spectroscopic Experimental Study of the Dinitromesithylen (DNM) Compared with the Theoretical Results

    NASA Astrophysics Data System (ADS)

    Brihi, O.; Medjroubi, M. L.; Hamdouni, N.; Meinnel, J.; Boucekkine, A.; Boudjada, A.

    The aim by our group is to understand the behaviour of the grouping methyl starting from the study of molecules having a great symmetry. In this part of work, it is had the crystalline structure of the dinitromesitylen (DNM) who is solved starting from the diffraction of x-rays starting from a monocrystal at the ambient temperature. Parallel to the experimental study, we undertook theoretical calculations conformation of the insulated molecule of DNM by using the methods of the DFT (Density Functional Theory).Calculations of optimization of the molecular conformation of the DNM by using the chain of program GAUSSIAN03 and functional MPW1PW91, B3LYP level with the 6-311G and LANL2DZ bases gave a conformation Cs with results very close to the experiment for the lengths and the angles of bond. The computation results obtained starting from the base set (6-311G) and functional MPW1PW91 give for the conformation of Dinitromesitylen (DNM) a good agreement of about a 1.9% for the lengths of bond and 1.2% for the angles of bond compared with the results of the diffraction of x-rays. Calculations of Raman and infra-red spectroscopy undertaken starting from the results of optimization by using same functional MPW1PW91 and B3LYP and the sets of bases 6-311G LanL2DZ led to the values of frequencies very close to the experimental results.

  4. Vibration Based Crack Detection in a Rotating Disk. Part 2; Experimental Results

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Haase, Wayne C.; Baaklini, George

    2005-01-01

    This paper describes the experimental results concerning the detection of a crack in a rotating disk. The goal was to utilize blade tip clearance and shaft vibration measurements to monitor changes in the system's center of mass and/or blade deformation behaviors. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system's center of mass occurs. Here, a notch was used to simulate an actual crack. The vibration based experimental results failed to identify the existence of a notch when utilizing the approach described above, even with a rather large, circumferential notch (l.2 in.) located approximately mid-span on the disk (disk radius = 4.63 in. with notch at r = 2.12 in.). This was somewhat expected, since the finite element based results in Part 1 of this study predicted changes in blade tip clearance as well as center of mass shifts due to a notch to be less than 0.001 in. Therefore, the small changes incurred by the notch could not be differentiated from the mechanical and electrical noise of the rotor system. Although the crack detection technique of interest failed to identify the existence ofthe notch, the vibration data produced and captured here will be utilized in upcoming studies that will focus on different data mining techniques concerning damage detection in a disk.

  5. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results

    PubMed Central

    Humada, Ali M.; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M.; Ahmed, Mushtaq N.

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  6. Comparison between experimental and analytical results for seesaw energy dissipation systems using fluid viscous dampers

    NASA Astrophysics Data System (ADS)

    Kang, Jae-Do; Tagawa, Hiroshi

    2016-03-01

    This paper presents results of experimental and numerical investigations of a seesaw energy dissipation system (SEDS) using fluid viscous dampers (FVDs). To confirm the characteristics of the FVDs used in the tests, harmonic dynamic loading tests were conducted in advance of the free vibration tests and the shaking table tests. Shaking table tests were conducted to demonstrate the damping capacity of the SEDS under random excitations such as seismic waves, and the results showed SEDSs have sufficient damping capacity for reducing the seismic response of frames. Free vibration tests were conducted to confirm the reliability of simplified analysis. Time history response analyses were also conducted and the results are in close agreement with shaking table test results.

  7. Photovoltaic Grid-Connected Modeling and Characterization Based on Experimental Results.

    PubMed

    Humada, Ali M; Hojabri, Mojgan; Sulaiman, Mohd Herwan Bin; Hamada, Hussein M; Ahmed, Mushtaq N

    2016-01-01

    A grid-connected photovoltaic (PV) system operates under fluctuated weather condition has been modeled and characterized based on specific test bed. A mathematical model of a small-scale PV system has been developed mainly for residential usage, and the potential results have been simulated. The proposed PV model based on three PV parameters, which are the photocurrent, IL, the reverse diode saturation current, Io, the ideality factor of diode, n. Accuracy of the proposed model and its parameters evaluated based on different benchmarks. The results showed that the proposed model fitting the experimental results with high accuracy compare to the other models, as well as the I-V characteristic curve. The results of this study can be considered valuable in terms of the installation of a grid-connected PV system in fluctuated climatic conditions. PMID:27035575

  8. Comparison of Computational and Experimental Microphone Array Results for an 18%-Scale Aircraft Model

    NASA Technical Reports Server (NTRS)

    Lockard, David P.; Humphreys, William M.; Khorrami, Mehdi R.; Fares, Ehab; Casalino, Damiano; Ravetta, Patricio A.

    2015-01-01

    An 18%-scale, semi-span model is used as a platform for examining the efficacy of microphone array processing using synthetic data from numerical simulations. Two hybrid RANS/LES codes coupled with Ffowcs Williams-Hawkings solvers are used to calculate 97 microphone signals at the locations of an array employed in the NASA LaRC 14x22 tunnel. Conventional, DAMAS, and CLEAN-SC array processing is applied in an identical fashion to the experimental and computational results for three different configurations involving deploying and retracting the main landing gear and a part span flap. Despite the short time records of the numerical signals, the beamform maps are able to isolate the noise sources, and the appearance of the DAMAS synthetic array maps is generally better than those from the experimental data. The experimental CLEAN-SC maps are similar in quality to those from the simulations indicating that CLEAN-SC may have less sensitivity to background noise. The spectrum obtained from DAMAS processing of synthetic array data is nearly identical to the spectrum of the center microphone of the array, indicating that for this problem array processing of synthetic data does not improve spectral comparisons with experiment. However, the beamform maps do provide an additional means of comparison that can reveal differences that cannot be ascertained from spectra alone.

  9. Supersonic Retropropulsion Experimental Results from the NASA Langley Unitary Plan Wind Tunnel

    NASA Technical Reports Server (NTRS)

    Berry, Scott A.; Rhode, Matthew N.; Edquist, Karl T.; Player, Charles J.

    2011-01-01

    A new supersonic retropropulsion experimental effort, intended to provide code validation data, was recently completed in the Langley Research Center Unitary Plan Wind Tunnel Test Section 2 over the Mach number range from 2.4 to 4.6. The experimental model was designed using insights gained from pre-test computations, which were instrumental for sizing and refining the model to minimize tunnel wall interference and internal flow separation concerns. A 5-in diameter 70-deg sphere-cone forebody with a roughly 10-in long cylindrical aftbody was the baseline configuration selected for this study. The forebody was designed to accommodate up to four 4:1 area ratio supersonic nozzles. Primary measurements for this model were a large number of surface pressures on the forebody and aftbody. Supplemental data included high-speed Schlieren video and internal pressures and temperatures. The run matrix was developed to allow for the quantification of various sources of experimental uncertainty, such as random errors due to run-to-run variations and bias errors due to flow field or model misalignments. Preliminary results and observations from the test are presented, while detailed data and uncertainty analyses are ongoing.

  10. Transdermal flux predictions for selected selective oestrogen receptor modulators (SERMs): comparison with experimental results.

    PubMed

    Güngör, Sevgi; Delgado-Charro, M Begoña; Masini-Etévé, Valérie; Potts, Russell O; Guy, Richard H

    2013-12-28

    The aim of this work was to evaluate the feasibility of delivering transdermally a series of highly lipophilic compounds (log P ~4-7), comprising several selective oestrogen receptor modulators and a modified testosterone (danazol). The maximum fluxes of the drugs were predicted theoretically using the modified Potts & Guy algorithm (to determine the permeability coefficient (kp) from water) and the calculated aqueous solubilities. The correction provided by Cleek & Bunge took into account the contribution of the viable epidermal barrier to the skin permeation of highly lipophilic compounds. Experimental measurements of drug fluxes from saturated hydroalcoholic solutions were determined in vitro through excised pig skin. Overall, the predicted fluxes were in good general agreement (within a factor of 10) with the experimental results. Most of the experimental fluxes were greater than those predicted theoretically suggesting that the 70:30 v/v ethanol-water vehicle employed may have had a modest skin penetration enhancement effect. This investigation shows that the transdermal fluxes of highly lipophilic compounds can be reasonably predicted from first principles provided that the viable epidermis, underlying the stratum corneum, is included as a potentially important contributor to the skin's overall barrier function. Furthermore, the absolute values of the measured fluxes, when considered in parallel with previous clinical studies, indicate that it might be feasible to topically deliver a therapeutically useful amount of some of the compounds considered to treat cancerous breast tissue. PMID:24076520

  11. Experimental results of the investigation of a laboratory cold seal TEC

    SciTech Connect

    Yarygin, V.I.; Mironov, V.S.; Kiryushenko, A.I.; Mikheyev, A.S.; Tulin, S.M.; Meleta, Y.A.; Yarygin, D.V.; Wolff, L.R.

    1998-07-01

    The results of experimental investigation of characteristics of a laboratory Cold Seal Thermionic Energy Converter (CS TEC) with a built-in gas regulated heat pipe are discussed. They were obtained to justify the electric-thermal-physical characteristics of a flame heated CS TEC. The CS TEC design is being developed by a joint Russian-Dutch team of researchers with support of the Netherlands Organization for Scientific Research (NWO). The concept of this flame heated Cold Seal TEC was presented in a previous publication. This paper deals with experimental data on the emission properties of electrodes and the voltage-current characteristics (JVC) of an electrically heated laboratory TEC. They were studied over a wide interval of variation in the electrode temperature and interelectrode distance. The cesium vapour working pressure in the interelectrode space was regulated both by the conventional method (using a cesium reservoir) and by means of a gas regulated cesium heat pipe. This allows one to use a rubber (viton) seal in the non-condensing gas (argon) area. The acquired experimental characteristics will allow one to identify the inner parameters at further stages of their work when testing the full-scale flame heated CS TEC.

  12. Comparison of experimental data with results of some drying models for regularly shaped products

    NASA Astrophysics Data System (ADS)

    Kaya, Ahmet; Aydın, Orhan; Dincer, Ibrahim

    2010-05-01

    This paper presents an experimental and theoretical investigation of drying of moist slab, cylinder and spherical products to study dimensionless moisture content distributions and their comparisons. Experimental study includes the measurement of the moisture content distributions of slab and cylindrical carrot, slab and cylindrical pumpkin and spherical blueberry during drying at various temperatures (e.g., 30, 40, 50 and 60°C) at specific constant velocity ( U = 1 m/s) and the relative humidity φ = 30%. In theoretical analysis, two moisture transfer models are used to determine drying process parameters (e.g., drying coefficient and lag factor) and moisture transfer parameters (e.g., moisture diffusivity and moisture transfer coefficient), and to calculate the dimensionless moisture content distributions. The calculated results are then compared with the experimental moisture data. A considerably high agreement is obtained between the calculations and experimental measurements for the cases considered. The effective diffusivity values were evaluated between 0.741 × 10-5 and 5.981 × 10-5 m2/h for slab products, 0.818 × 10-5 and 6.287 × 10-5 m2/h for cylindrical products and 1.213 × 10-7 and 7.589 × 10-7 m2/h spherical products using the Model-I and 0.316 × 10-5-5.072 × 10-5 m2/h for slab products, 0.580 × 10-5-9.587 × 10-5 m2/h for cylindrical products and 1.408 × 10-7-13.913 × 10-7 m2/h spherical products using the Model-II.

  13. SWAP Modeling Results of Monitored Soil Water Moisture Data of Irrigation Experimental Study

    NASA Astrophysics Data System (ADS)

    Zeiliger, A.; Garsia-Orenes, F.; van den Elsen, E.; Mataix-Solera, J.; Semenov, V.

    2009-04-01

    In arid and semiarid zones of the Mediterranean regions a shortage of fresh water resources constitutes some time dramatic problem. In these regions with growing population and the scarce of rainfall irregularity in time during growing season an efficient use of water irrigation became a main challenge for future extensive agriculture development. In the frame of FP6 Water-Reuse project 516731 project a special field experimentation has been carried out in Alicante Region of Spain (Location UTM X: 693.809, Y: 4.279.922, Z: 626) on a Sandy Typic Xerofkuvent (Soil Survey Staff, 1999), Calcaric Fluvisol (WRB, FAO, 1989). with aim to investigate water regime in water repellent soils under irrigation of vine Vitus Labrusca. During field experimentation from 2006 till 2008 on 9 plots, there the same regime of irrigation water application was maintained, a monitoring of weather parameters was done by automatic meteorological station as well as a monitoring of soil water moisture was done by set of data-loggers and TDR-soil moisture sensors ECO-2 installed at different depts. SWAP model was used to simulate water regime of irrigated plots. Empirical coefficients of van Genuchten-Mualem's equations were calculated by pedotransfer functions derived from HYPRES data base using measured values of bulk density, organic matter content and soil texture. Testing of validity of the use of estimated curves was done by comparison with unsaturated soil hydraulic parameters of water retention and hydraulic conductivity measured in vitro by Wind's method on soil samples. Calibration of SWAP model for each plot was done on measured soil moisture data of irrigation events by adjusting a value of saturated hydraulic coefficient. Verification of the SWAP model was done by full range of experimental data. Similarity and non-similarity of the water regime at experimental plots as well as results of verification of SWAP model were analyzed

  14. Low power underwater acoustic DPSK detection: Theoretical prediction and experimental results

    NASA Astrophysics Data System (ADS)

    Dunne, Andrew

    This thesis presents two methods of analyzing the effectiveness of a prototype differential phase-shift keying (DPSK) detection circuit. The first method is to make modifications to the existing hardware to reliably output and record the cross-correlation values of the DPSK detection process. The second method is to write a MATLAB detection algorithm which accurately simulates the detection results of the hardware system without the need of any electronics. These two systems were tested and verified with a bench test using computer generated DPSK signals. The hardware system was tested using real acoustic data from shallow and deep water at-sea tests to determine the effectiveness of the DPSK detection circuit in different ocean environments. The hydrophone signals from the tests were recorded so that the cross-correlation values could be verified using the MATLAB detector. As a result of this study, these two systems provided more insight into how well the DPSK detection prototype works and helped to identify ways of improving the detection reliability and overall performance of the prototype DPSK detection circuit.

  15. Seeded free electron laser operating with two colors: Comments on experimental results

    NASA Astrophysics Data System (ADS)

    Carpanese, M.; Ciocci, F.; Dattoli, G.; Petralia, A.; Petrillo, V.; Torre, A.

    2016-05-01

    Free electron lasers operating with two colors are promising devices for applications. The relevant modelization has provided a good understanding of the underlying physics. In this paper we present an analysis of the experimental results obtained at SPARC_LAB concerning seeded two-colors free electron laser (FEL) operation. The use of an ad hoc developed semi-analytical model based on the small-signal FEL integral equation reproduces most of the observed phenomenology. The paper discusses the reliability of the proposed method, the range of validity and its possible improvement.

  16. Comparison of Theoretical Stresses and Deflections of Multicell Wings with Experimental Results Obtained from Plastic Models

    NASA Technical Reports Server (NTRS)

    Zender, George W

    1956-01-01

    The experimental deflections and stresses of six plastic multicell-wing models of unswept, delta, and swept plan form are presented and compared with previously published theoretical results obtained by the electrical analog method. The comparisons indicate that the theory is reliable except for the evaluation of stresses in the vicinity of the leading edge of delta wings and the leading and trailing edges of swept wings. The stresses in these regions are questionable, apparently because of simplifications employed in idealizing the actual structure for theoretical purposes and because of local effects of concentrated loads.

  17. Experimental results of a deflected thrust V/STOL nozzle research program

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Johns, A. L.

    1983-01-01

    Four deflected thrust nozzle concepts, designed to operate at the low pressure ratio typical of high bypass-ratio turbofan engines for medium speed (subsonic) V/STOL aircraft, were studied. Maps of overall performance characteristics and exit velocity distributions are used to highlight similarities and differences between the four concepts. Analytically determined secondary flows at the exit of a 90 deg circular pipe bend are compared with the experimental results from the more complex three dimensional geometries. The relative impact of total-pressure losses and secondary flows on nozzle thrust coefficient is addressed by numerical integration of exit velocity measurements. Previously announced in STAR as N83-25657

  18. Experimental results of a deflected thrust V/STOL nozzle research program

    NASA Technical Reports Server (NTRS)

    Burstadt, P. L.; Johns, A. L.

    1983-01-01

    Four deflected thrust nozzle concepts, designed to operate at the low pressure ratio typical of high bypass-ratio turbofan engines for medium speed (subsonic) V/STOL aircraft, were studied. Maps of overall performance characteristics and exit velocity distributions are used to highlight similarities and differences between the four concepts. Analytically determined secondary flows at the exit of a 90 deg circular pipe bend are compared with the experimental results from the more complex three dimensional geometries. The relative impact of total-pressure losses and secondary flows on nozzle thrust coefficient is addressed by numerical integration of exit velocity measurements.

  19. Development of X-ray microcalorimeters based on SOI technology and experimental results

    NASA Astrophysics Data System (ADS)

    Szeflinski, V.; Aliane, A.; De Moro, F.; Pigot, C.; Sauvageot, J.-L.; Agnèse, P.; Gasse, A.; Ribot, H.; Gremion, E.; De La Broise, X.; Navick, X. F.

    2009-10-01

    We are developing an X-ray spectro-imaging detector at cryogenic temperature (<100 mK) for next space generation missions, using silicon technology. Each pixel of this array detector is made of a tantalum absorber bonded by indium bump hybridization, to an implanted and high-temperature diffused silicon thermistor. The thermo-mechanical link, provided by the indium bump hybridization, is being improved in terms of thermal capacitance. We present the state of development and experimental results on this new generation of X-ray microcalorimeters.

  20. Experimental and Theoretical Results in Output-Trajectory Redesign for Flexible Structures

    NASA Technical Reports Server (NTRS)

    Dewey, J. S.; Devasia, Santosh

    1996-01-01

    In this paper we study the optimal redesign of output trajectory for linear invertible systems. This is particularly important for tracking control of flexible structures because the input-state trajectories that achieve the required output may cause excessive vibrations in the structure. A trade-off is then required between tracking and vibrations reduction. We pose and solve this problem as the minimization of a quadratic cost function. The theory is developed and applied to the output tracking of a flexible structure and experimental results are presented.

  1. Active vibration absorber for the CSI evolutionary model - Design and experimental results. [Controls Structures Interaction

    NASA Technical Reports Server (NTRS)

    Bruner, Anne M.; Belvin, W. Keith; Horta, Lucas G.; Juang, Jer-Nan

    1991-01-01

    The development of control of large flexible structures technology must include practical demonstrations to aid in the understanding and characterization of controlled structures in space. To support this effort, a testbed facility has been developed to study practical implementation of new control technologies under realistic conditions. The paper discusses the design of a second order, acceleration feedback controller which acts as an active vibration absorber. This controller provides guaranteed stability margins for collocated sensor/actuator pairs in the absence of sensor/actuator dynamics and computational time delay. Experimental results in the presence of these factors are presented and discussed. The robustness of this design under model uncertainty is demonstrated.

  2. Recent experimental results from a long-pulse J-band relativistic klystron amplifier developmental effort

    SciTech Connect

    Kato, K.G.; Crouch, D.D.; Sar, D.R.; Speciale, R.A.; Carlsten, B.E.; Fazio, M.V.; Haynes, W.B.; Stringfield, R.M.

    1994-12-31

    Recent experimental results, supporting simulations, and design modeling are presented from a developmental effort to a produce a long pulse ({approximately}1{mu}s) J-band (5.85-8.2 GHz) relativistic klystron amplifier (RKA) of the high current NRL genealogy. This RKA is designed to operate at approximately 6.6 GHz, with a desired RF output {approximately}700 MW. Conversion of electron beam energy to microwave energy is obtained by a mock magnetically insulated coaxial converter which, in various incarnations, can be made to be either a cavity gap extractor or an inverse cathode.

  3. Experimental Results From the Thermal Energy Storage-1 (TES-1) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Jacqmin, David

    1995-01-01

    The Thermal Energy Storage (TES) experiments are designed to provide data to help researchers understand the long-duration microgravity behavior of thermal energy storage fluoride salts that undergo repeated melting and freezing. Such data, which have never been obtained before, have direct application to space-based solar dynamic power systems. These power systems will store solar energy in a thermal energy salt, such as lithium fluoride (LiF) or a eutectic of lithium fluoride/calcium difluoride (LiF-CaF2) (which melts at a lower temperature). The energy will be stored as the latent heat of fusion when the salt is melted by absorbing solar thermal energy. The stored energy will then be extracted during the shade portion of the orbit, enabling the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes have been developed to predict the performance of a spacebased solar dynamic power system. However, the analytical predictions must be verified experimentally before the analytical results can be used for future space power design applications. Four TES flight experiments will be used to obtain the needed experimental data. This article focuses on the flight results from the first experiment, TES-1, in comparison to the predicted results from the Thermal Energy Storage Simulation (TESSIM) analytical computer code.

  4. Impulsivity in Multiplayer Online Battle Arena Gamers: Preliminary Results on Experimental and Self-Report Measures.

    PubMed

    Nuyens, Filip; Deleuze, Jory; Maurage, Pierre; Griffiths, Mark D; Kuss, Daria J; Billieux, Joël

    2016-06-01

    Background and aims Multiplayer Online Battle Arena (MOBA) games have become the most popular type of video games played worldwide, superseding the playing of Massively Multiplayer Online Role-Playing Games and First-Person Shooter games. However, empirical studies focusing on the use and abuse of MOBA games are still very limited, particularly regarding impulsivity, which is an indicator of addictive states but has not yet been explored in MOBA games. In this context, the objective of the present study is to explore the associations between impulsivity and symptoms of addictive use of MOBA games in a sample of highly involved League of Legends (LoL, currently the most popular MOBA game) gamers. Methods Thirty-six LoL gamers were recruited and completed both experimental (Single Key Impulsivity Paradigm) and self-reported impulsivity assessments (s-UPPS-P Impulsive Behavior Scale, Barratt Impulsiveness Scale), in addition to an assessment of problematic video game use (Problematic Online Gaming Questionnaire). Results Results showed links between impulsivity-related constructs and signs of excessive MOBA game involvement. Findings indicated that impaired ability to postpone rewards in an experimental laboratory task was strongly related to problematic patterns of MOBA game involvement. Although less consistent, several associations were also found between self-reported impulsivity traits and signs of excessive MOBA game involvement. Conclusions Despite these results are preliminary and based upon a small (self-selected) sample, the present study highlights potential psychological factors related to the addictive use of MOBA games. PMID:27156376

  5. Investigation of sonar transponders for offshore wind farms: modeling approach, experimental setup, and results.

    PubMed

    Fricke, Moritz B; Rolfes, Raimund

    2013-11-01

    The installation of offshore wind farms in the German Exclusive Economic Zone requires the deployment of sonar transponders to prevent collisions with submarines. The general requirements for these systems have been previously worked out by the Research Department for Underwater Acoustics and Marine Geophysics of the Bundeswehr. In this article, the major results of the research project "Investigation of Sonar Transponders for Offshore Wind Farms" are presented. For theoretical investigations a hybrid approach was implemented using the boundary element method to calculate the source directivity and a three-dimensional ray-tracing algorithm to estimate the transmission loss. The angle-dependence of the sound field as well as the weather-dependence of the transmission loss are compared to experimental results gathered at the offshore wind farm alpha ventus, located 45 km north of the island Borkum. While theoretical and experimental results are in general agreement, the implemented model slightly underestimates scattering at the rough sea surface. It is found that the source level of 200 dB re 1 μPa at 1 m is adequate to satisfy the detectability of the warning sequence at distances up to 2 NM (≈3.7 km) within a horizontal sector of ±60° if realistic assumptions about signal-processing and noise are made. An arrangement to enlarge the angular coverage is discussed. PMID:24180764

  6. Femtosecond laser for glaucoma treatment: the comparison between simulation and experimentation results on ocular tissue removal

    NASA Astrophysics Data System (ADS)

    Hou, Dong Xia; Ngoi, Bryan K. A.; Hoh, Sek Tien; Koh, Lee Huat K.; Deng, Yuan Zi

    2005-04-01

    In ophthalmology, the use of femtosecond lasers is receiving more attention than ever due to its extremely high intensity and ultra short pulse duration. It opens the highly beneficial possibilities for minimized side effects during surgery process, and one of the specific areas is laser surgery in glaucoma treatment. However, the sophisticated femtosecond laser-ocular tissue interaction mechanism hampers the clinical application of femtosecond laser to treat glaucoma. The potential contribution in this work lies in the fact, that this is the first time a modified moving breakdown theory is applied, which is appropriate for femtosecond time scale, to analyze femtosecond laser-ocular tissue interaction mechanism. Based on this theory, energy deposition and corresponding thermal increase are studied by both simulation and experimentation. A simulation model was developed using Matlab software, and the simulation result was validated through in-vitro laser-tissue interaction experiment using pig iris. By comparing the theoretical and experimental results, it is shown that femtosecond laser can obtain determined ocular tissue removal, and the thermal damage is evidently reduced. This result provides a promising potential for femtosecond laser in glaucoma treatment.

  7. A Comparison of Experimental and Theoretical Results for Labyrinth Gas Seals. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Scharrer, Joseph Kirk

    1987-01-01

    The basic equations are derived for a two control volume model for compressible flow in a labyrinth seal. The flow is assumed to be completely turbulent and isoenergetic. The wall friction factors are determined using the Blasius formula. Jet flow theory is used for the calculation of the recirculation velocity in the cavity. Linearized zeroth and first order perturbation equations are developed for small motion about a centered position by an expansion in the eccentricity ratio. The zeroth order pressure distribution is found by satisfying the leakage equation. The circumferential velocity distribution is determined by satisfying the momentum equations. The first order equations are solved by a separation of variable solution. Integration of the resultant pressure distribution along and around the seal defines the reaction force developed by the seal and the corresponding dynamic coefficients. The results of this analysis are compared to experimental test results.

  8. Heavy vehicle suspension parameters identification and estimation of vertical forces: experimental results

    NASA Astrophysics Data System (ADS)

    Imine, H.; Madani, T.

    2015-02-01

    The aim of the present work is to estimate the vertical forces of heavy vehicle and identify the unknown dynamic parameters using sliding mode observer approach. This observation needs a good knowledge of dynamic parameters such as damping coefficient, spring stiffness, etc. In this paper, suspension stiffness and unsprung masses have been identified. Experimental results carried out on an instrumented tractor have been presented in order to show the quality of the state observation, parameters identification and force estimation. These estimation results are then compared to the measured one coming from the sensors installed in the tractor. Many scenarios have been tested. In this paper, the results coming from zigzag test have been shown and commented.

  9. Experimental results for a two-dimensional supersonic inlet used as a thrust deflecting nozzle

    NASA Technical Reports Server (NTRS)

    Johns, Albert L.; Burstadt, Paul L.

    1984-01-01

    Nearly all supersonic V/STOL aircraft concepts are dependent on the thrust deflecting capability of a nozzle. In one unique concept, referred to as the reverse flow dual fan, not only is there a thrust deflecting nozzle for the fan and core engine exit flow, but because of the way the propulsion system operates during vertical takeoff and landing, the supersonic inlet is also used as a thrust deflecting nozzle. This paper presents results of an experimental study to evaluate the performance of a supersonic inlet used as a thrust deflecting nozzle for this reverse flow dual fan concept. Results are presented in terms of nozzle thrust coefficient and thrust vector angle for a number of inlet/nozzle configurations. Flow visualization and nozzle exit flow survey results are also shown.

  10. Strain measurement of objects subjected to aerodynamic heating using digital image correlation: experimental design and preliminary results.

    PubMed

    Pan, Bing; Jiang, Tianyun; Wu, Dafang

    2014-11-01

    In thermomechanical testing of hypersonic materials and structures, direct observation and quantitative strain measurement of the front surface of a test specimen directly exposed to severe aerodynamic heating has been considered as a very challenging task. In this work, a novel quartz infrared heating device with an observation window is designed to reproduce the transient thermal environment experienced by hypersonic vehicles. The specially designed experimental system allows the capture of test article's surface images at various temperatures using an optical system outfitted with a bandpass filter. The captured images are post-processed by digital image correlation to extract full-field thermal deformation. To verify the viability and accuracy of the established system, thermal strains of a chromiumnickel austenite stainless steel sample heated from room temperature up to 600 °C were determined. The preliminary results indicate that the air disturbance between the camera and the specimen due to heat haze induces apparent distortions in the recorded images and large errors in the measured strains, but the average values of the measured strains are accurate enough. Limitations and further improvements of the proposed technique are discussed. PMID:25430144

  11. Fuel-rich, catalytic reaction experimental results. [fuel development for high-speed civil transport aircraft

    NASA Technical Reports Server (NTRS)

    Rollbuhler, Jim

    1991-01-01

    Future aeropropulsion gas turbine combustion requirements call for operating at very high inlet temperatures, pressures, and large temperature rises. At the same time, the combustion process is to have minimum pollution effects on the environment. Aircraft gas turbine engines utilize liquid hydrocarbon fuels which are difficult to uniformly atomize and mix with combustion air. An approach for minimizing fuel related problems is to transform the liquid fuel into gaseous form prior to the completion of the combustion process. Experimentally obtained results are presented for vaporizing and partially oxidizing a liquid hydrocarbon fuel into burnable gaseous components. The presented experimental data show that 1200 to 1300 K reaction product gas, rich in hydrogen, carbon monoxide, and light-end hydrocarbons, is formed when flowing 0.3 to 0.6 fuel to air mixes through a catalyst reactor. The reaction temperatures are kept low enough that nitrogen oxides and carbon particles (soot) do not form. Results are reported for tests using different catalyst types and configurations, mass flowrates, input temperatures, and fuel to air ratios.

  12. Comparison of experimental and analytical results for free vibration of laminated composite plates

    SciTech Connect

    Maryuama, Koichi; Narita, Yoshihiro; Ichinomiya, Osamu

    1995-11-01

    Fibrous composite materials are being increasingly employed in high performance structures, including pressured vessel and piping applications. These materials are usually used in the form of laminated flat or curved plates, and the understanding of natural frequencies and the corresponding mode shapes is essential to a reliable structural design. Although many references have been published on analytical study of laminated composite plates, a limited number of experimental studies have appeared for dealing with vibration characteristics of the plates. This paper presents both experimental and analytical results for the problems. In the experiment, the holographic interferometry is used to measure the resonant frequencies and corresponding mode shapes of six-layered CFRP (carbon fiber reinforced plastic) composite plates. The material constants of a lamina are calculated from fiber and matrix material constants by using some different composite rules. With the calculated constants, the natural frequencies of the laminated CFRP plates are theoretically determined by the Ritz method. From the comparison of two sets of the results, the effect of choosing different composite rules is discussed in the vibration study of laminated composite plates.

  13. Tilted wheel satellite attitude control with air-bearing table experimental results

    NASA Astrophysics Data System (ADS)

    Inumoh, Lawrence O.; Forshaw, Jason L.; Horri, Nadjim M.

    2015-12-01

    Gyroscopic actuators for satellite control have attracted significant research interest over the years, but their viability for the control of small satellites has only recently started to become clear. Research on variable speed gyroscopic actuators has long been focused on single gimbal actuators; double gimbal actuators typically operate at constant wheel spin rate and allow tilt angle ranges far larger than the ranges needed to operate most satellite missions. This research examines a tilted wheel, a newly proposed type of inertial actuator that can generate torques in all three principal axes of a rigid satellite using a spinning wheel and a double tilt mechanism. The tilt mechanism tilts the angular momentum vector about two axes providing two degree of freedom control, while variation of the wheel speed provides the third. The equations of motion of the system lead to a singularity-free system during nominal operation avoiding the need for complex steering logic. This paper describes the hardware design of the tilted wheel and the experimental setup behind both standalone and spherical air-bearing tables used to test it. Experimental results from the air bearing table are provided with the results depicting the high performance capabilities of the proposed actuator in torque generation.

  14. Experimental Impeller Fragmentation of Iliocaval Thrombosis Under Tulip Filter Protection: Preliminary Results

    SciTech Connect

    Schmitz-Rode, Thomas; Vorwerk, Dierk; Schuermann, Karl; Guenther, Rolf W.

    1996-04-15

    Purpose: To assess the efficacy of catheter fragmentation of massive caval thrombosis and of filter protection against procedure-related pulmonary embolism. Methods: In 10 sheep, a self-expanding tulip-shaped filter made from Wallstent mesh (diameter 25 mm) was introduced from the right jugular approach into the proximal inferior vena cava. Experimentally induced massive iliocaval thrombosis was fragmented by an impeller catheter (expanded diameter 14 mm), which was advanced coaxially through the sheath of the expanded filter. Post-procedural cavography and pulmonary angiography were performed to document the extent of caval recanalization and pulmonary embolism. Results: In all cases, impeller fragmentation cleared the inferior vena cava and the iliac veins of thrombi completely. Fragments washed downstream were trapped in the filter. In two of the first cases, parts of the clots caused pulmonary embolism before the filter was in place. Further events were avoided by a modification of the experimental setup. Except for some small peripheral perfusion defects in two cases, pulmonary angiograms did not show any incidence of pulmonary embolism. Conclusion: Our preliminary results suggest that impeller fragmentation of iliocaval thrombi under tulip filter protection is effective and does not cause significant pulmonary embolism.

  15. Natural frequencies of two bubbles in a compliant tube: Analytical, simulation, and experimental results

    PubMed Central

    Jang, Neo W.; Zakrzewski, Aaron; Rossi, Christina; Dalecki, Diane; Gracewski, Sheryl

    2011-01-01

    Motivated by various clinical applications of ultrasound contrast agents within blood vessels, the natural frequencies of two bubbles in a compliant tube are studied analytically, numerically, and experimentally. A lumped parameter model for a five degree of freedom system was developed, accounting for the compliance of the tube and coupled response of the two bubbles. The results were compared to those produced by two different simulation methods: (1) an axisymmetric coupled boundary element and finite element code previously used to investigate the response of a single bubble in a compliant tube and (2) finite element models developed in comsol Multiphysics. For the simplified case of two bubbles in a rigid tube, the lumped parameter model predicts two frequencies for in- and out-of-phase oscillations, in good agreement with both numerical simulation and experimental results. For two bubbles in a compliant tube, the lumped parameter model predicts four nonzero frequencies, each asymptotically converging to expected values in the rigid and compliant limits of the tube material. PMID:22088008

  16. Epistemology and expectations survey about experimental physics: Development and initial results

    NASA Astrophysics Data System (ADS)

    Zwickl, Benjamin M.; Hirokawa, Takako; Finkelstein, Noah; Lewandowski, H. J.

    2014-06-01

    In response to national calls to better align physics laboratory courses with the way physicists engage in research, we have developed an epistemology and expectations survey to assess how students perceive the nature of physics experiments in the contexts of laboratory courses and the professional research laboratory. The Colorado Learning Attitudes about Science Survey for Experimental Physics (E-CLASS) evaluates students' epistemology at the beginning and end of a semester. Students respond to paired questions about how they personally perceive doing experiments in laboratory courses and how they perceive an experimental physicist might respond regarding their research. Also, at the end of the semester, the E-CLASS assesses a third dimension of laboratory instruction, students' reflections on their course's expectations for earning a good grade. By basing survey statements on widely embraced learning goals and common critiques of teaching labs, the E-CLASS serves as an assessment tool for lab courses across the undergraduate curriculum and as a tool for physics education research. We present the development, evidence of validation, and initial formative assessment results from a sample that includes 45 classes at 20 institutions. We also discuss feedback from instructors and reflect on the challenges of large-scale online administration and distribution of results.

  17. Experimental and raytrace results for throat-to-throat compound parabolic concentrators

    NASA Technical Reports Server (NTRS)

    Leviton, D. B.; Leitch, J. W.

    1986-01-01

    Compound parabolic concentrators are nonimaging cone-shaped optics with useful angular transmission characteristics. Two cones used throat-to-throat accept radiant flux within one well-defined acceptance angle and redistribute it into another. If the entrance cone is fed with Lambertian flux, the exit cone produces a beam whose half-angle is the exit cone's acceptance angle and whose cross section shows uniform irradiance from near the exit mouth to infinity. (The pair is a beam angle transformer). The design of one pair of cones is discussed, also an experiment to map the irradiance of the emergent beam, and a raytracing program which models the cones fed by Lambertian flux. Experimental results compare favorably with raytrace results.

  18. Experimental Results for a Flapped Natural-laminar-flow Airfoil with High Lift/drag Ratio

    NASA Technical Reports Server (NTRS)

    Mcghee, R. J.; Viken, J. K.; Pfenninger, W.; Beasley, W. D.; Harvey, W. D.

    1984-01-01

    Experimental results have been obtained for a flapped natural-laminar-flow airfoil, NLF(1)-0414F, in the Langley Low-Turbulence Pressure Tunnel. The tests were conducted over a Mach number range from 0.05 to 0.40 and a chord Reynolds number range from about 3.0 x 10(6) to 22.0 x 10(6). The airfoil was designed for 0.70 chord laminar flow on both surfaces at a lift coefficient of 0.40, a Reynolds number of 10.0 x 10(6), and a Mach number of 0.40. A 0.125 chord simple flap was incorporated in the design to increase the low-drag, lift-coefficient range. Results were also obtained for a 0.20 chord split-flap deflected 60 deg.

  19. The Langley Research Center CSI phase-0 evolutionary model testbed-design and experimental results

    NASA Technical Reports Server (NTRS)

    Belvin, W. K.; Horta, Lucas G.; Elliott, K. B.

    1991-01-01

    A testbed for the development of Controls Structures Interaction (CSI) technology is described. The design philosophy, capabilities, and early experimental results are presented to introduce some of the ongoing CSI research at NASA-Langley. The testbed, referred to as the Phase 0 version of the CSI Evolutionary model (CEM), is the first stage of model complexity designed to show the benefits of CSI technology and to identify weaknesses in current capabilities. Early closed loop test results have shown non-model based controllers can provide an order of magnitude increase in damping in the first few flexible vibration modes. Model based controllers for higher performance will need to be robust to model uncertainty as verified by System ID tests. Data are presented that show finite element model predictions of frequency differ from those obtained from tests. Plans are also presented for evolution of the CEM to study integrated controller and structure design as well as multiple payload dynamics.

  20. Non-Shock Initiation of the Plastic Bonded Explosive PBXN-5: Experimental Results

    NASA Astrophysics Data System (ADS)

    Lappo, K. N.; Todd, S. N.; Anderson, M. U.; Vogler, T. J.

    2007-12-01

    The plastic bonded explosive PBXN-5 was studied under impulsive loading experiments to relate impact-induced mechanical damage to the onset of, and the extent of reaction produced. A small diameter projectile generated shock and release conditions at the impact interface, on the microsecond time scale during the initial portion of the impulsive loading. These shock and release wave interactions generate significant damage, resulting in a porous, powder compaction-type initiation behavior. Experimental measurements show an energy threshold for initiation of reaction which relates to impact-induced kinetic energy. These results are implemented in the model development and validation phases of the damage-induced reaction (DMGIR) model, which is used to simulate impact scenarios of explosives, explosive components, and explosive systems.

  1. A three-phase series-parallel resonant converter -- analysis, design, simulation, and experimental results

    SciTech Connect

    Bhat, A.K.S.; Zheng, R.L.

    1996-07-01

    A three-phase dc-to-dc series-parallel resonant converter is proposed /and its operating modes for a 180{degree} wide gating pulse scheme are explained. A detailed analysis of the converter using a constant current model and the Fourier series approach is presented. Based on the analysis, design curves are obtained and a design example of a 1-kW converter is given. SPICE simulation results for the designed converter and experimental results for a 500-W converter are presented to verify the performance of the proposed converter for varying load conditions. The converter operates in lagging power factor (PF) mode for the entire load range and requires a narrow variation in switching frequency, to adequately regulate the output power.

  2. Comparison of results of experimental research with numerical calculations of a model one-sided seal

    NASA Astrophysics Data System (ADS)

    Joachimiak, Damian; Krzyślak, Piotr

    2015-06-01

    Paper presents the results of experimental and numerical research of a model segment of a labyrinth seal for a different wear level. The analysis covers the extent of leakage and distribution of static pressure in the seal chambers and the planes upstream and downstream of the segment. The measurement data have been compared with the results of numerical calculations obtained using commercial software. Based on the flow conditions occurring in the area subjected to calculations, the size of the mesh defined by parameter y+ has been analyzed and the selection of the turbulence model has been described. The numerical calculations were based on the measurable thermodynamic parameters in the seal segments of steam turbines. The work contains a comparison of the mass flow and distribution of static pressure in the seal chambers obtained during the measurement and calculated numerically in a model segment of the seal of different level of wear.

  3. Fault detection, isolation and reconfiguration in FTMP Methods and experimental results. [fault tolerant multiprocessor

    NASA Technical Reports Server (NTRS)

    Lala, J. H.

    1983-01-01

    The Fault-Tolerant Multiprocessor (FTMP) is a highly reliable computer designed to meet a goal of 10 to the -10th failures per hour and built with the objective of flying an active-control transport aircraft. Fault detection, identification, and recovery software is described, and experimental results obtained by injecting faults in the pin level in the FTMP are presented. Over 21,000 faults were injected in the CPU, memory, bus interface circuits, and error detection, masking, and error reporting circuits of one LRU of the multiprocessor. Detection, isolation, and reconfiguration times were recorded for each fault, and the results were found to agree well with earlier assumptions made in reliability modeling.

  4. Experimental results on the design for the APS PID global orbit control system.

    SciTech Connect

    Chung, Y.; Kirchman, J. A.

    1997-12-05

    The Advanced Photon Source third generation synchrotrons light source needs a stabilized particle beam position to produce high brightness and low emittance radiation. Global orbit correction control is introduced and is utilized to satisfy the demanding needs of the accelerator. This paper presents the experimental results for determining an effective and optimal controller to meet the global orbit correction requirements. These requirements include frequency/time domain demands consisting of vibrational noise attenuation, limiting of controller gains for stability and improving the system time response. Experiments were conducted with a digital signal processor implementing various PID sets to make comparisons between simulations and experiments. Measurements at these PID sets supported the results of software simulation.

  5. Low pollution combustor designs for CTOL engines - Results of the Experimental Clean Combustor Program

    NASA Technical Reports Server (NTRS)

    Roberts, R.; Peduzzi, A.; Niedzwiecki, R. W.

    1976-01-01

    The NASA/Pratt & Whitney Aircraft Experimental Clean Combustor Program is a multi-year, major contract effort. Primary program objectives are the generation of combustor technology for development of advanced commercial CTOL engines with lower exhaust emissions than current aircraft and demonstration of this technology in a full-scale JT9D engine in 1976. This paper describes the pollution and performance goals, Phase I and II test results, and the Phase III combustor hardware, pollution sampling techniques, and test plans. Best results were obtained with the Vorbix concept which employs multiple burning zones and improved fuel preparation and distribution. Substantial reductions were achieved in all pollutant categories, meeting the 1979 EPA standards for NOx, THC, and smoke when extrapolated to JT9D cycle conditions. The Vorbix concept additionally demonstrated the capability for acceptable altitude relight and did not appear to have unsolvable durability or exit temperature distribution problems.

  6. Preliminary results of the large experimental wind turbine phase of the national wind energy program

    NASA Technical Reports Server (NTRS)

    Thomas, R. L.; Sholes, J. E.

    1975-01-01

    A major phase of the wind energy program is the development of reliable wind turbines for supplying cost-competitive electrical energy. This paper discusses the preliminary results of two projects in this phase of the program. First an experimental 100 kW wind turbine design and its status are reviewed. Also discussed are the results of two parallel design studies for determining the configurations and power levels for wind turbines with minimum energy costs. These studies show wind energy costs of 7 to 1.5 c/kWH for wind turbines produced in quantities of 100 to 1000 a year and located at sites having average winds of 12 to 18 mph.

  7. Survey of Experimental Results in High-Contrast Imaging for Future Exoplanet Missions

    NASA Technical Reports Server (NTRS)

    Lawson, P. R.; Belikov, R.; Cash, W.; Clampin, M.; Glassman, T.; Guyon, O.; Kasdin, N. J.; Kern, B. D.; Lyon, R.; Mawet, D.; Moody, D.; Samuele, R.; Serabyn, E.; Sirbu, D.; Trauger, J.

    2013-01-01

    We present and compare experimental results in high contrast imaging representing the state of the art in coronagraph and starshade technology. These experiments have been undertaken with the goal of demonstrating the capability of detecting Earth-like planets around nearby Sun-like stars. The contrast of an Earth seen in reflected light around a Sun-like star would be about 1.2 x 10(exp -10). Several of the current candidate technologies now yield raw contrasts of 1.0 x 10(exp -9) or better, and so should enable the detection of Earths, assuming a gain in sensitivity in post-processing of a factor of 10. We present results of coronagraph and starshade experiments conducted at visible and infrared wavelengths. Cross-sections of dark fields are directly compared as a function of field angle and bandwidth. The strength and differences of the techniques are compared.

  8. Interfacial Chemical Interactions in the (Alumina/Graphite/Al Alloys) System: Thermodynamic Modeling and Experimental Results

    NASA Astrophysics Data System (ADS)

    Gelbstein, M.; Edry, I.; Froumin, N.; Frage, N.

    2009-04-01

    The stability of alumina-coated graphite couples in liquid Al is investigated in the 1373 to 1573 K temperature range. A thermodynamic model was carried out to determine the mechanisms controlling the couple stability and the effect of alloying Al with high melting point element for instance U (up to 3 at. pct). It was established that the dissolved uranium dose not play any role in the interfacial interactions and that the couple stability is governed by the interactions with Al resulting in the release of gaseous products. The experiments focused on wetting kinetics under conditions allowing for an in-situ reduction of the alumina coating by the liquid Al. The experimental results confirm the predictions of the thermodynamic analysis.

  9. Heat Transfer Enhancement for Finned-Tube Heat Exchangers with Vortex Generators: Experimental and Numerical Results

    SciTech Connect

    O'Brien, James Edward; Sohal, Manohar Singh; Huff, George Albert

    2002-08-01

    A combined experimental and numerical investigation is under way to investigate heat transfer enhancement techniques that may be applicable to large-scale air-cooled condensers such as those used in geothermal power applications. The research is focused on whether air-side heat transfer can be improved through the use of finsurface vortex generators (winglets,) while maintaining low heat exchanger pressure drop. A transient heat transfer visualization and measurement technique has been employed in order to obtain detailed distributions of local heat transfer coefficients on model fin surfaces. Pressure drop measurements have also been acquired in a separate multiple-tube row apparatus. In addition, numerical modeling techniques have been developed to allow prediction of local and average heat transfer for these low-Reynolds-number flows with and without winglets. Representative experimental and numerical results presented in this paper reveal quantitative details of local fin-surface heat transfer in the vicinity of a circular tube with a single delta winglet pair downstream of the cylinder. The winglets were triangular (delta) with a 1:2 height/length aspect ratio and a height equal to 90% of the channel height. Overall mean fin-surface Nusselt-number results indicate a significant level of heat transfer enhancement (average enhancement ratio 35%) associated with the deployment of the winglets with oval tubes. Pressure drop measurements have also been obtained for a variety of tube and winglet configurations using a single-channel flow apparatus that includes four tube rows in a staggered array. Comparisons of heat transfer and pressure drop results for the elliptical tube versus a circular tube with and without winglets are provided. Heat transfer and pressure-drop results have been obtained for flow Reynolds numbers based on channel height and mean flow velocity ranging from 700 to 6500.

  10. Recovery of yttrium from cathode ray tubes and lamps’ fluorescent powders: experimental results and economic simulation

    SciTech Connect

    Innocenzi, V. De Michelis, I.; Ferella, F.; Vegliò, F.

    2013-11-15

    Highlights: • Fluorescent powder of lamps. • Fluorescent powder of cathode ray rubes. • Recovery of yttrium from fluorescent powders. • Economic simulation for the processes to recover yttrium from WEEE. - Abstract: In this paper, yttrium recovery from fluorescent powder of lamps and cathode ray tubes (CRTs) is described. The process for treating these materials includes the following: (a) acid leaching, (b) purification of the leach liquors using sodium hydroxide and sodium sulfide, (c) precipitation of yttrium using oxalic acid, and (d) calcinations of oxalates for production of yttrium oxides. Experimental results have shown that process conditions necessary to purify the solutions and recover yttrium strongly depend on composition of the leach liquor, in other words, whether the powder comes from treatment of CRTs or lamp. In the optimal experimental conditions, the recoveries of yttrium oxide are about 95%, 55%, and 65% for CRT, lamps, and CRT/lamp mixture (called MIX) powders, respectively. The lower yields obtained during treatments of MIX and lamp powders are probably due to the co-precipitation of yttrium together with other metals contained in the lamps powder only. Yttrium loss can be reduced to minimum changing the experimental conditions with respect to the case of the CRT process. In any case, the purity of final products from CRT, lamps, and MIX is greater than 95%. Moreover, the possibility to treat simultaneously both CRT and lamp powders is very important and interesting from an industrial point of view since it could be possible to run a single plant treating fluorescent powder coming from two different electronic wastes.

  11. A Review of Out-of-School Time Program Quasi-Experimental and Experimental Evaluation Results. Out-of-School Time Evaluation Snapshot.

    ERIC Educational Resources Information Center

    Little, Priscilla M. D.; Harris, Erin

    As the amount of resources allocated to out-of-school (OST) programming and policymakers' demands for research-based results increase, there is increasing interest in rigorous research designs to examine OST program outcomes. This issue of "Out-of-School Time Evaluation Snapshots" reviews 27 quasi-experimental and experimental OST evaluations and…

  12. Results from the HARPS-N 2014 Campaign to Estimate Accurately the Densities of Planets Smaller than 2.5 Earth Radii

    NASA Astrophysics Data System (ADS)

    Charbonneau, David; Harps-N Collaboration

    2015-01-01

    Although the NASA Kepler Mission has determined the physical sizes of hundreds of small planets, and we have in many cases characterized the star in detail, we know virtually nothing about the planetary masses: There are only 7 planets smaller than 2.5 Earth radii for which there exist published mass estimates with a precision better than 20 percent, the bare minimum value required to begin to distinguish between different models of composition.HARPS-N is an ultra-stable fiber-fed high-resolution spectrograph optimized for the measurement of very precise radial velocities. We have 80 nights of guaranteed time per year, of which half are dedicated to the study of small Kepler planets.In preparation for the 2014 season, we compared all available Kepler Objects of Interest to identify the ones for which our 40 nights could be used most profitably. We analyzed the Kepler light curves to constrain the stellar rotation periods, the lifetimes of active regions on the stellar surface, and the noise that would result in our radial velocities. We assumed various mass-radius relations to estimate the observing time required to achieve a mass measurement with a precision of 15%, giving preference to stars that had been well characterized through asteroseismology. We began by monitoring our long list of targets. Based on preliminary results we then selected our final short list, gathering typically 70 observations per target during summer 2014.These resulting mass measurements will have a signifcant impact on our understanding of these so-called super-Earths and small Neptunes. They would form a core dataset with which the international astronomical community can meaningfully seek to understand these objects and their formation in a quantitative fashion.HARPS-N was funded by the Swiss Space Office, the Harvard Origin of Life Initiative, the Scottish Universities Physics Alliance, the University of Geneva, the Smithsonian Astrophysical Observatory, the Italian National

  13. EASE (Experimental Assembly of Structures in EVA) overview of selected results

    NASA Technical Reports Server (NTRS)

    Akin, David L.

    1987-01-01

    Experimental Assembly of Structures in EVA (EASE) objectives, experimental protocol, neutral buoyancy simulation, task time distribution, assembly task performance, metabolic rate/biomedical readouts are summarized. This presentation is shown in charts, figures, and graphs.

  14. Copper Content in Synthetic Copper Carbonate: A Statistical Comparison of Experimental and Expected Results

    NASA Astrophysics Data System (ADS)

    Sheeran, Daniel

    1998-04-01

    This paper describes a general chemistry experiment which was implemented in the 1995-96 academic year and which is based on the preparation of a basic copper(II) carbonate, Cu(OH)2(CO3), and its analysis for copper. Individual results of the copper determination were compiled and a class mean and standard deviation were computed and a frequency plot was constructed for the purpose of comparing class results to the expected result. From a student perspective, the expected result was not Cu(OH)2(CO3), rather it was CuCO3. Students were unaware that they prepared a basic salt, and assumed they prepared CuCO3. This assumption originates in the synthesis which has the appearance of a double displacement reaction. Students expected the copper determination to verify this assumption and were quite surprised when it did not. Statistics was used to reveal the discrepancy between experimental and expected results, and a t-test established that this discrepancy was significant--the prepared material cannot be formulated as CuCO3. The statistical conclusion was further substantiated by observational evidence in the synthesis and analysis steps.

  15. Smectite clays in Mars soil - Evidence for their presence and role in Viking biology experimental results

    NASA Technical Reports Server (NTRS)

    Banin, A.; Rishpon, J.

    1979-01-01

    Evidence for the presence of smectite clays in Martian soils is reviewed and results of experiments with certain active clays simulating the Viking biology experiments are reported. Analyses of Martian soil composition by means of X-ray fluorescence spectrometry and dust storm spectroscopy and Martian geological history strongly suggest the presence of a mixture of weathered ferro-silicate minerals, mainly nontronite and montmorillonite, accompanied by soluble sulphate salts, as major constituents. Samples of montmorillonite and nontronite incubated with (C-14)-formate or the radioactive nutrient medium solution used in the Viking Labeled Release experiment, were found to produce patterns of release of radioactive gas very similar to those observed in the Viking experiments, indicating the iron-catalyzed decomposition of formate as the reaction responsible for the Viking results. The experimental results of Hubbard (1979) simulating the results of the Viking Pyrolytic Release experiment using iron montmorillonites are pointed out, and it is concluded that many of the results of the Viking biology experiments can be explained in terms of the surface activity of smectite clays in catalysis and adsorption.

  16. Induced current electrical impedance tomography system: experimental results and numerical simulations.

    PubMed

    Zlochiver, Sharon; Radai, M Michal; Abboud, Shimon; Rosenfeld, Moshe; Dong, Xiu-Zhen; Liu, Rui-Gang; You, Fu-Sheng; Xiang, Hai-Yan; Shi, Xue-Tao

    2004-02-01

    In electrical impedance tomography (EIT), measurements of developed surface potentials due to applied currents are used for the reconstruction of the conductivity distribution. Practical implementation of EIT systems is known to be problematic due to the high sensitivity to noise of such systems, leading to a poor imaging quality. In the present study, the performance of an induced current EIT (ICEIT) system, where eddy current is applied using magnetic induction, was studied by comparing the voltage measurements to simulated data, and examining the imaging quality with respect to simulated reconstructions for several phantom configurations. A 3-coil, 32-electrode ICEIT system was built, and an iterative modified Newton-Raphson algorithm was developed for the solution of the inverse problem. The RMS norm between the simulated and the experimental voltages was found to be 0.08 +/- 0.05 mV (<3%). Two regularization methods were implemented and compared: the Marquardt regularization and the Laplacian regularization (a bounded second-derivative regularization). While the Laplacian regularization method was found to be preferred for simulated data, it resulted in distinctive spatial artifacts for measured data. The experimental reconstructed images were found to be indicative of the angular positioning of the conductivity perturbations, though the radial sensitivity was low, especially when using the Marquardt regularization method. PMID:15005319

  17. Experimental Estimation Of Energy Damping During Free Rocking Of Unreinforced Masonry Walls. First Results

    SciTech Connect

    Sorrentino, Luigi; Masiani, Renato; Benedetti, Stefano

    2008-07-08

    This paper presents an ongoing experimental program on unreinforced masonry walls undergoing free rocking. Aim of the laboratory campaign is the estimation of kinetic energy damping exhibited by walls released with non-zero initial conditions of motion. Such energy damping is necessary for dynamic modelling of unreinforced masonry local mechanisms. After a brief review of the literature on this topic, the main features of the laboratory tests are presented. The program involves the experimental investigation of several parameters: 1) unit material (brick or tuff), 2) wall aspect ratio (ranging between 14.5 and 7.1), 3) restraint condition (two-sided or one-sided rocking), and 4) depth of the contact surface between facade and transverse walls (one-sided rocking only). All walls are single wythe and the mortar is pozzuolanic. The campaign is still in progress. However, it is possible to present the results on most of the mechanical properties of mortar and bricks. Moreover, a few time histories are reported, already indicating the need to correct some of the assumptions frequent in the literature.

  18. Preliminary results of the LLNL airborne experimental test-bed SAR system

    SciTech Connect

    Miller, M.G.; Mullenhoff, C.J.; Kiefer, R.D.; Brase, J.M.; Wieting, M.G.; Berry, G.L.; Jones, H.E.

    1996-01-16

    The Imaging and Detection Program (IDP) within Laser Programs at Lawrence Livermore National Laboratory (LLNL) in cooperation with the Hughes Aircraft Company has developed a versatile, high performance, airborne experimental test-bed (AETB) capability. The test-bed has been developed for a wide range of research and development experimental applications including radar and radiometry plus, with additional aircraft modifications, optical systems. The airborne test-bed capability has been developed within a Douglas EA-3B Skywarrior jet aircraft provided and flown by Hughes Aircraft Company. The current test-bed payload consists of an X-band radar system, a high-speed data acquisition, and a real-time processing capability. The medium power radar system is configured to operate in a high resolution, synthetic aperture radar (SAR) mode and is highly configurable in terms of waveforrns, PRF, bandwidth, etc. Antennas are mounted on a 2-axis gimbal in the belly radome of the aircraft which provides pointing and stabilization. Aircraft position and antenna attitude are derived from a dedicated navigational system and provided to the real-time SAR image processor for instant image reconstruction and analysis. This paper presents a further description of the test-bed and payload subsystems plus preliminary results of SAR imagery.

  19. Experimental results and modeling tests of an adsorptive air-conditioning unit

    SciTech Connect

    Guilleminot, J.J.; Poyelle, F.; Meunier, F.

    1998-10-01

    Experimental tests have been performed on a zeolite-water adsorptive system suitable for air conditioning and consisting of two adsorbers filled with a consolidated composite made of zeolite mixed with a highly conductive matrix. This paper describes the experimental results of such a heat pump unit operating with a heat and mass recovery cycle. An important enhancement of the specific cooling power (SCP) has been achieved. At evaporating temperature T = 4 C, mass transfer resistance controls the process and limits the expected COP. Tests carried out at higher evaporating pressure make it possible to achieve the predicted COP and SCP. A predictive model developed and validated elsewhere in order to describe the temperature evolution of components and the heat and mass transfer in the adsorbers explains the mass transfer resistance in the adsorbent. Last, a new highly conductive adsorbent composite with good mass transfer properties is developed. The model is used to predict the performances of this new material. Very good SCP and COP can be achieved.

  20. Experimental results of flooding experiments in an inclined tube with liquid nitrogen and its vapor

    NASA Astrophysics Data System (ADS)

    Chen, Jianye; Xu, Lu; Xiong, Wei; Qiu, Limin; Zhang, Xiaobin

    2014-07-01

    Counter-current two-phase flow behaviors of saturated liquid nitrogen and its vapor at the onset of flooding are experimentally investigated. The experiments are carried out in a vacuum-insulated 20 mm i.d. transparent tube with the inclination angles of 30°, 45° and 60° corresponding to the horizontal. The common slug flow phenomenon happened with water-air is not observed with liquid nitrogen-vapor, instead, the big interfacial wave is found to be crushed to tiny droplets. The phenomenal difference is primarily attributed to the larger viscosity of water than liquid nitrogen. Correspondingly, the sharp rise of pressure drop with water-air is largely due to the blockage of gas flow by the formed slug, while it is primarily due to the tiny droplet entrainment for the liquid nitrogen-vapor pairs. The effects of inclination angles on the incipient flooding velocity are specially emphasized and investigated. A new correlation base on Ohnesorge number and modified Froude number are presented, and the results coincide with the experimental data of both room-temperature and cryogenic fluids with the uncertainty of 20%.

  1. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    NASA Astrophysics Data System (ADS)

    Menapace, E.; Birattari, C.; Bonardi, M. L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-01

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  2. Frequency-dependent seismic attenuation in shales: experimental results and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Delle Piane, Claudio; Sarout, Joel; Madonna, Claudio; Saenger, Erik H.; Dewhurst, David N.; Raven, Mark

    2014-07-01

    Samples of shales from the Ordovician Bongabinni and Goldwyer source rock formations were recovered from the Canning Basin (Western Australia). Attenuation was experimentally measured on preserved plugs from these formations in the frequency range between 10-2 and 102 Hz. Samples cored with different orientations with respect to the sedimentary bedding were prepared and tested in their native saturated state and after drying in the oven at 105 °C for 24 hr to assess the effect of fluids and of the sediment anisotropy on attenuation. To aid the interpretation of the experimental results, the clay-rich samples were characterized in terms of mineralogy, water content, porosity, permeability and microstructure. The two shales have significantly different quality factors; and this is seen to be dependent on both the saturation state of the samples and the propagation direction of the oscillatory signal. The attenuation coefficient for compression/extension parallel to bedding is less than that vertical to bedding in both the preserved and partially dehydrated situations. No frequency dependency is observed in the preserved samples within the range of frequencies explored in this study. On the other hand partially saturated samples show peaks in attenuation at around 40 Hz when the stress perturbation is transmitted normal to the macroscopic bedding. The interpretation of the attenuation measurements in terms of well-established theoretical models is discussed in view of the physical characteristics and microstructure of the tested rocks.

  3. Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides

    SciTech Connect

    Menapace, E.; Birattari, C.; Bonardi, M.L.; Groppi, F.; Morzenti, S.; Zona, C.

    2005-05-24

    The radionuclide production for biomedical applications has been brought up in the years, as a special nuclear application, at INFN LASA Laboratory, particularly in co-operation with the JRC-Ispra of EC. Mainly scientific aspects concerning radiation detection and the relevant instruments, the measurements of excitation functions of the involved nuclear reactions, the requested radiochemistry studies and further applications have been investigated. On the side of the nuclear data evaluations, based on nuclear model calculations and critically selected experimental data, the appropriate competence has been developed at ENEA Division for Advanced Physics Technologies. A series of high specific activity accelerator-produced radionuclides in no-carrier-added (NCA) form, for uses in metabolic radiotherapy and for PET radiodiagnostics, are investigated. In this work, last revised measurements and model calculations are reviewed for excitation functions of natZn(d,X)64Cu, 66Ga reactions, referring to irradiation experiments at K=38 variable energy Cyclotron of JRC-Ispra. Concerning the reaction data for producing 186gRe and 211At/211gPo (including significant emission spectra) and 210At, most recent and critically selected experimental results are considered and discussed in comparison with model calculations paying special care to pre-equilibrium effects estimate and to the appropriate overall parameterization. Model calculations are presented for 226Ra(p,2n)225Ac reaction, according to the working program of the ongoing IAEA CRP on the matter.

  4. Experimental Results from the Thermal Energy Storage-1 (TES-1) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Wald, Lawrence W.; Tolbert, Carol; Jacqmin, David

    1995-01-01

    The Thermal Energy Storage-1 (TES-1) is a flight experiment that flew on the Space Shuttle Columbia (STS-62), in March 1994, as part of the OAST-2 mission. TES-1 is the first experiment in a four experiment suite designed to provide data for understanding the long duration microgravity behavior of thermal energy storage fluoride salts that undergo repeated melting and freezing. Such data have never been obtained before and have direct application for the development of space-based solar dynamic (SD) power systems. These power systems will store solar energy in a thermal energy salt such as lithium fluoride or calcium fluoride. The stored energy is extracted during the shade portion of the orbit. This enables the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes have been developed for predicting performance of a spaced-based solar dynamic power system. Experimental verification of the analytical predictions is needed prior to using the analytical results for future space power design applications. The four TES flight experiments will be used to obtain the needed experimental data. This paper will focus on the flight results from the first experiment, TES-1, in comparison to the predicted results from the Thermal Energy Storage Simulation (TESSIM) analytical computer code. The TES-1 conceptual development, hardware design, final development, and system verification testing were accomplished at the NASA lewis Research Center (LeRC). TES-1 was developed under the In-Space Technology Experiment Program (IN-STEP), which sponsors NASA, industry, and university flight experiments designed to enable and enhance space flight technology. The IN-STEP Program is sponsored by the Office of Space Access and Technology (OSAT).

  5. Drying in porous media with gravity-stabilized fronts: experimental results.

    PubMed

    Yiotis, A G; Salin, D; Tajer, E S; Yortsos, Y C

    2012-08-01

    In a recent paper [Yiotis et al., Phys. Rev. E 85, 046308 (2012)] we developed a model for the drying of porous media in the presence of gravity. It incorporated effects of corner film flow, internal and external mass transfer, and the effect of gravity. Analytical results were derived when gravity opposes drying and hence leads to a stable percolation drying front. In this paper, we test the theory using laboratory experiments. A series of isothermal drying experiments in glass bead packings saturated with volatile hydrocarbons is conducted. The transparent glass cells containing the packing allow for the visual monitoring of the phase distribution patterns below the surface, including the formation of liquid films, as the gaseous phase invades the pore space, and for the control of the thickness of the diffusive mass boundary layer over the packing. The experimental results agree very well with theory, provided that the latter is generalized to account for the effects of corner roundness in the film region (which was neglected in the theoretical part). We demonstrate the existence of an early constant rate period (CRP), which lasts as long as the films saturate the surface of the packing, and of a subsequent falling rate period (FRP), which begins practically after the detachment of the film tips from the external surface. During the CRP, the process is controlled by diffusion within the stagnant gaseous phase in the upper part of the cells, yielding a Stefan tube problem solution. During the FRP, the process is controlled by diffusion within the packing, with a drying rate inversely proportional to the observed position of the film tips in the cell. Theoretical and experimental results compare favorably for a specific value of the roundness of the films, which is found to be constant and equal to 0.2 for various conditions, and verify the theoretical dependence on the capillary Ca(f), Bond Bo, and Sherwood Sh numbers. PMID:23005857

  6. Immiscible liquid-liquid pressure-driven flow in capillary tubes: Experimental results and numerical comparison

    NASA Astrophysics Data System (ADS)

    Soares, Edson J.; Thompson, Roney L.; Niero, Debora C.

    2015-08-01

    The immiscible displacement of one viscous liquid by another in a capillary tube is experimentally and numerically analyzed in the low inertia regime with negligible buoyancy effects. The dimensionless numbers that govern the problem are the capillary number Ca and the viscosity ratio of the displaced to the displacing fluids Nμ. In general, there are two output quantities of interest. One is associated to the relation between the front velocity, Ub, and the mean velocity of the displaced fluid, U ¯ 2 . The other is the layer thickness of the displaced fluid that remains attached to the wall. We compute these quantities as mass fractions in order to make them able to be compared. In this connection, the efficiency mass fraction, me, is defined as the complement of the mass fraction of the displaced fluid that leaves the tube while the displacing fluid crosses its length. The geometric mass fraction, mg, is defined as the fraction of the volume of the layer that remains attached to the wall. Because in gas-liquid displacement, these two quantities coincide, it is not uncommon in the literature to use mg as a measure of the displacement efficiency for liquid-liquid displacements. However, as is shown in the present paper, these two quantities have opposite tendencies when we increase the viscosity of the displacing fluid, making this distinction a crucial aspect of the problem. Results from a Galerkin finite element approach are also presented in order to make a comparison. Experimental and numerical results show that while the displacement efficiency decreases, the geometrical fraction increases when the viscosity ratio decreases. This fact leads to different decisions depending on the quantity to be optimized. The quantitative agreement between the numerical and experimental results was not completely achieved, especially for intermediate values of Ca. The reasons for that are still under investigation. The experiments conducted were able to achieve a wide range

  7. Motion effects on an IFR hovering task: Analytical predictions and experimental results

    NASA Technical Reports Server (NTRS)

    Ringland, R. F.; Stapleford, R. L.; Magdaleno, R. E.

    1971-01-01

    An analytical pilot model incorporating the effects of motion cues and display scanning and sampling is tested by comparing predictions against experimental results on a moving base simulator. The simulated task is that of precision hovering of a VTOL having varying amounts of rate damping, and using separated instrument displays. Motion cue effects are investigated by running the experiment under fixed and moving base conditions, the latter in two modes; full motion, and angular motion only. Display scanning behavior is measured on some of the runs. The results of the program show that performance is best with angular motion only, most probably because a g-vector tilt cue is available to the pilot in this motion condition. This provides an attitude indication even when not visually fixating the attitude display. Vestibular threshold effects are also present in the results because of the display scaling used to permit hovering position control within the motion simulator limits; no washouts are used in the simulator drive signals. The IFR nature of the task results in large decrements in pilot opinion and performance relative to VFR conditions because of the scanning workload. Measurements of scanning behavior are sensitive to motion conditions and show more attention to attitude control under fixed base conditions.

  8. Preliminary experimental results on studying possibility of variable mass liner (VML) formation

    SciTech Connect

    1995-12-31

    The main objective of the present experiment was to study the formation process and initial stage of acceleration of a variable-mass plasma liner (VML). The method is based on magnetic acceleration of a liner with the mass reduced during such acceleration. The experiment was carried out on February 16 at VNIIEF. This report describes the results of measurements obtained in the experiment and preliminary analysis of the results characterizing operation of the test facility main units: helical EMG; 5-module disk EMG 400 mm in diameter (DEMG); ponderomotive unit (PU) with a cylindric condensed liner and a special tooth-cutoff. The first part of the report presents measurement results obtained on the VNIIEF`s diagnostic equipment that are compared with those obtained by American specialists on their diagnostic equipment. Information submitted by American specialists is included in part 2 of this report. The second part of the report presents preliminary computational-theoretic analysis of the main measured results describing operation of DEMG TL system in the experiment; experimental data are compared with theoretical ones obtained before and after the experiment. But more emphasis is placed on the data preliminary analysis indicating that in the experiment a variable mass liner is formed (VML or plasma bubble).

  9. Experimental and computer simulation results of the spot welding process using SORPAS software

    NASA Astrophysics Data System (ADS)

    Al-Jader, M. A.; Cullen, J. D.; Athi, N.; Al-Shamma'a, A. I.

    2009-07-01

    The highly competitive nature of the automotive industry drives demand for improvements and increased precision engineering in resistance spot welding. Currently there are about 4300 weld points on the average steel vehicle. Current industrial monitoring systems check the quality of the nugget after processing 15 cars, once every two weeks. The nuggets are examined off line using a destructive process, which takes approximately 10 days to complete causing a long delay in the production process. This paper presents a simulation of the spot welding growth curves, along with a comparison to growth curves performed on an industrial spot welding machine. The correlation of experimental results shows that SORPAS simulations can be used as an off line measurement to reduce factory energy usage. The first section in your paper

  10. Lateral and axial resolutions of an angle-deviation microscope for different numerical apertures: experimental results

    NASA Astrophysics Data System (ADS)

    Chiu, Ming-Hung; Lai, Chin-Fa; Tan, Chen-Tai; Lin, Yi-Zhi

    2011-03-01

    This paper presents a study of the lateral and axial resolutions of a transmission laser-scanning angle-deviation microscope (TADM) with different numerical aperture (NA) values. The TADM is based on geometric optics and surface plasmon resonance principles. The surface height is proportional to the phase difference between two marginal rays of the test beam, which is passed through the test medium. We used common-path heterodyne interferometry to measure the phase difference in real time, and used a personal computer to calculate and plot the surface profile. The experimental results showed that the best lateral and axial resolutions for NA = 0.41 were 0.5 μm and 3 nm, respectively, and the lateral resolution breaks through the diffraction limits.

  11. Inlet Flow Test Calibration for a Small Axial Compressor Facility. Part 1: Design and Experimental Results

    NASA Technical Reports Server (NTRS)

    Miller, D. P.; Prahst, P. S.

    1994-01-01

    An axial compressor test rig has been designed for the operation of small turbomachines. The inlet region consisted of a long flowpath region with two series of support struts and a flapped inlet guide vane. A flow test was run to calibrate and determine the source and magnitudes of the loss mechanisms in the inlet for a highly loaded two-stage axial compressor test. Several flow conditions and IGV angle settings were established in which detailed surveys were completed. Boundary layer bleed was also provided along the casing of the inlet behind the support struts and ahead of the IGV. A detailed discussion of the flowpath design along with a summary of the experimental results are provided in Part 1.

  12. Deuteron induced reactions on Ho and La: Experimental excitation functions and comparison with code results

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Adam-Rebeles, R.; Tarkanyi, F.; Takacs, S.; Csikai, J.; Takacs, M. P.; Ignatyuk, A.

    2013-09-01

    Activation products of rare earth elements are gaining importance in medical and technical applications. In stacked foil irradiations, followed by high resolution gamma spectroscopy, the cross-sections for production of 161,165Er, 166gHo on 165Ho and 135,137m,137g,139Ce, 140La, 133m,133g,cumBa and 136Cs on natLa targets were measured up to 50 MeV. Reduced uncertainty is obtained by simultaneous remeasurement of the 27Al(d,x)24,22Na monitor reactions over the whole energy range. A comparison with experimental literature values and results from updated theoretical codes (ALICE-D, EMPIRE-D and the TENDL2012 online library) is discussed.

  13. School Context and Educational Outcomes: Results from a Quasi-Experimental Study

    PubMed Central

    Casciano, Rebecca; Massey, Douglas S.

    2013-01-01

    In this study we draw on data from a quasi-experimental study to test whether moving into a subsidized housing development in an affluent suburb yields educational benefits to the children of residents, compared to the educations they would have received had they not moved into the development. Results suggest that resident children experienced a significant improvement in school quality compared with a comparison group of students whose parents also had applied for residence. Parents who were residents of the development also displayed higher levels of school involvement compared with the comparison group of non-resident parents, and their children were exposed to significantly lower levels of school disorder and violence within school and spent more time reading outside of school. Living in the development did not influence GPA directly, but did indirectly increase GPA by increasing the time residents spent reading outside of school. PMID:25342878

  14. Rainfall estimation using microwave links. Results from an experimental setup in Luxembourg

    NASA Astrophysics Data System (ADS)

    Fenicia, Fabrizio; Matgen, Patrick; Pfister, Laurent

    2010-05-01

    Microwave links represent a valid alternative to traditional rainfall estimation methods. They are commonly used in mobile phone communication, and they constitute built-in widely distributed networks. Due to their ability of providing high temporal and spatial resolution measurements, their use is particularly suitable in urban settings. We here show results from an experimental setup in Luxembourg City, where two dual frequency links have been installed. The links cover a distance of about 4km, and measure power attenuation at 1 min. timestep. The links have been equipped with several recording raingauges, which measure rainfall in real-time communicating through a wireless connection. This set-up has been used to analyze in detail the mapping between attenuation and rainfall intensity, and gain insights into the potential accuracy of these instruments. In addition, we investigated the relation between rainfall and discharge response of the urban area of Luxembourg, which shows the potential utility of high frequency rainfall measurements for urban environments.

  15. Knowledge-Aided Multichannel Adaptive SAR/GMTI Processing: Algorithm and Experimental Results

    NASA Astrophysics Data System (ADS)

    Wu, Di; Zhu, Daiyin; Zhu, Zhaoda

    2010-12-01

    The multichannel synthetic aperture radar ground moving target indication (SAR/GMTI) technique is a simplified implementation of space-time adaptive processing (STAP), which has been proved to be feasible in the past decades. However, its detection performance will be degraded in heterogeneous environments due to the rapidly varying clutter characteristics. Knowledge-aided (KA) STAP provides an effective way to deal with the nonstationary problem in real-world clutter environment. Based on the KA STAP methods, this paper proposes a KA algorithm for adaptive SAR/GMTI processing in heterogeneous environments. It reduces sample support by its fast convergence properties and shows robust to non-stationary clutter distribution relative to the traditional adaptive SAR/GMTI scheme. Experimental clutter suppression results are employed to verify the virtue of this algorithm.

  16. Noise characteristics of upper surface blown configurations. Experimental program and results

    NASA Technical Reports Server (NTRS)

    Brown, W. H.; Searle, N.; Blakney, D. F.; Pennock, A. P.; Gibson, J. S.

    1977-01-01

    An experimental data base was developed from the model upper surface blowing (USB) propulsive lift system hardware. While the emphasis was on far field noise data, a considerable amount of relevant flow field data were also obtained. The data were derived from experiments in four different facilities resulting in: (1) small scale static flow field data; (2) small scale static noise data; (3) small scale simulated forward speed noise and load data; and (4) limited larger-scale static noise flow field and load data. All of the small scale tests used the same USB flap parts. Operational and geometrical variables covered in the test program included jet velocity, nozzle shape, nozzle area, nozzle impingement angle, nozzle vertical and horizontal location, flap length, flap deflection angle, and flap radius of curvature.

  17. Active vibration absorber for CSI evolutionary model: Design and experimental results

    NASA Technical Reports Server (NTRS)

    Bruner, Anne M.; Belvin, W. Keith; Horta, Lucas G.; Juang, Jer-Nan

    1991-01-01

    The development of control of large flexible structures technology must include practical demonstration to aid in the understanding and characterization of controlled structures in space. To support this effort, a testbed facility was developed to study practical implementation of new control technologies under realistic conditions. The design is discussed of a second order, acceleration feedback controller which acts as an active vibration absorber. This controller provides guaranteed stability margins for collocated sensor/actuator pairs in the absence of sensor/actuator dynamics and computational time delay. The primary performance objective considered is damping augmentation of the first nine structural modes. Comparison of experimental and predicted closed loop damping is presented, including test and simulation time histories for open and closed loop cases. Although the simulation and test results are not in full agreement, robustness of this design under model uncertainty is demonstrated. The basic advantage of this second order controller design is that the stability of the controller is model independent.

  18. 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.

  19. Experimental Results from Droop Compensation for the High Voltage Converter Modulators

    SciTech Connect

    Patel, Gunjan P; Anderson, David E; Peplov, Vladimir V; Saethre, Robert B; Solley, Dennis J; Wezensky, Mark W

    2013-01-01

    The High Voltage Convertor Modulators are used to power the RF klystrons used throughout the linear accelerator at the Spallation Neutron Source. The output voltage of the modulator has significant voltage droop and ripple which, combined with low level RF system limitations, affect performance and stability of the accelerator cavities. In conjunction with the progress in the development of the new controller, different modulation techniques were implemented and studied on the test modulator. This paper discusses experimental results from implementation of different modulation schemes has on the modulator output voltage pulse. Thermal measurements were carried out to determine the effect of these modulations schemes on long term reliability of the modulator. Future plans are also discussed.

  20. An aerodynamic analysis of the autogiro rotor with a comparison between calculated and experimental results

    NASA Technical Reports Server (NTRS)

    Wheatley, John B

    1935-01-01

    This report presents an extension of the autogiro theory of Glauert and Lock in which the influence of a pitch varying with the blade radius is evaluated and methods of approximating the effect of blade tip losses and the influence of reversed velocities on the retreating blades are developed. A comparison of calculated and experimental results showed that most of the rotor characteristics could be calculated with reasonable accuracy, and that the type of induced flow assumed has a secondary effect upon the net rotor forces, although the flapping motion is influenced appreciably. An approximate evaluation of the effect of parasite drag on the rotor blades established the importance of including this factor in the analysis.

  1. Physical model and experimental results of cathode erosion related to power supply ripple

    NASA Technical Reports Server (NTRS)

    Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.

    1992-01-01

    This paper discusses the physical effects of power supply ripple on cathode erosion and cathode arc attachment in a water-cooled, 30 kW nitrogen arcjet. Experimental results are presented for 2 percent thoriated tungsten, which show that the long-term cathode erosion rate is a decreasing function of current ripple over the range 1-13 percent. Above this range, the cathode discharge becomes unstable, and the erosion rate rapidly increases. A qualitative model of this effect is given in terms of a magnetically induced radial motion of the arc column, and an overall increase in the cathode spot radius due to the higher peak current associated with higher ripple. The most important effect of power supply ripple is therefore shown to be its ability to collectively drive the cathode attachment away from the cathode center. This leads to an increase in the cathode attachment area, and a subsequent decrease in the cathode erosion rate.

  2. Simulation and experimental results of optical and thermal modeling of gold nanoshells.

    PubMed

    Ghazanfari, Lida; Khosroshahi, Mohammad E

    2014-09-01

    This paper proposes a generalized method for optical and thermal modeling of synthesized magneto-optical nanoshells (MNSs) for biomedical applications. Superparamagnetic magnetite nanoparticles with diameter of 9.5 ± 1.4 nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8 ± 3.5 nm MNSs. In this paper, simulations and detailed analysis are carried out for different nanoshell geometry to achieve a maximum heat power. Structural, magnetic and optical properties of MNSs are assessed using vibrating sample magnetometer (VSM), X-ray diffraction (XRD), UV-VIS spectrophotometer, dynamic light scattering (DLS), and transmission electron microscope (TEM). Magnetic saturation of synthesized magnetite nanoparticles are reduced from 46.94 to 11.98 emu/g after coating with gold. The performance of the proposed optical-thermal modeling technique is verified by simulation and experimental results. PMID:25063109

  3. Optical constants of Titan aerosols and their tholins analogs: Experimental results and modeling/observational data

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

    2015-05-01

    Since Bishun Khare's pioneer works on Titan tholins, many studies have been performed to improve the experimental database of the optical constants of Titan tholins. The determination of the optical constants of Titan aerosols is indeed essential to quantify their capacity to absorb and scatter solar radiation, and thus to evaluate their role on Titan's radiative balance and climate. The study of the optical properties is also crucial to analyze and better interpret many of Titan's observational data, in particular those acquired during the Cassini-Huygens mission. This review paper critically summarizes these new results and presents constraints on Titan's aerosols optical constants. Finally, the information lacking in this field is highlighted as well as some possible investigations that could be carried out to fill these gaps.

  4. NACA0012 benchmark model experimental flutter results with unsteady pressure distributions

    NASA Technical Reports Server (NTRS)

    Rivera, Jose A., Jr.; Dansberry, Bryan E.; Bennett, Robert M.; Durham, Michael H.; Silva, Walter A.

    1992-01-01

    The Structural Dynamics Division at NASA Langley Research Center has started a wind tunnel activity referred to as the Benchmark Models Program. The primary objective of this program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type computational fluid dynamics codes currently in use or under development. The program is a multi-year activity that will involve testing of several different models to investigate various aeroelastic phenomena. This paper describes results obtained from a second wind tunnel test of the first model in the Benchmark Models Program. This first model consisted of a rigid semispan wing having a rectangular planform and a NACA 0012 airfoil shape which was mounted on a flexible two degree of freedom mount system. Experimental flutter boundaries and corresponding unsteady pressure distribution data acquired over two model chords located at the 60 and 95 percent span stations are presented.

  5. First experimental results of the BNL inverse free electron laser accelerator

    SciTech Connect

    Steenbergen, A. van; Gallardo, J.; Babzien, M.; Skaritka, J.; Wang, X.J.; Sandweiss, J.; Fang, J.M.; Qiu, X.

    1996-10-01

    A 40 MeV electron beam, using the inverse3e free-electron laser interaction, has been accelerated by {Delta}E/E = 2.5% over a distance of 0.47 m. The electrons interact with a 1--2 GW CO{sub 2} laser beam bounded by a 2.8 mm ID sapphire circular waveguide in the presence of a tapered wiggler with Bmax {approx} 1 T and a period 2.89 cm {le} {lambda}{sub w} {le} 3.14 cm. The experimental results of {Delta}E/E as a function of electron energy E, peak magnetic field Bw and laser power W{sub 1} compare well with analytical and 1-D numerical simulations and permit scaling to higher laser power and electron energy.

  6. Experimental results of active control on a large structure to suppress vibration

    NASA Technical Reports Server (NTRS)

    Dunn, H. J.

    1991-01-01

    Three design methods, Linear Quadratic Gaussian with Loop Transfer Recovery (LQG/LTR), H-infinity, and mu-synthesis, are used to obtain compensators for suppressing the vibrations of a 10-bay vertical truss structure, a component typical of what may be used to build a large space structure. For the design process the plant dynamic characteristics of the structure were determined experimentally using an identification method. The resulting compensators were implemented on a digital computer and tested for their ability to suppress the first bending mode response of the 10-bay vertical truss. Time histories of the measured motion are presented, and modal damping obtained during the experiments are compared with analytical predictions. The advantages and disadvantages of using the various design methods are discussed.

  7. Some experimental results on the L-star instability of metallized composite propellants. [combustion instability

    NASA Technical Reports Server (NTRS)

    Kumar, R. N.

    1975-01-01

    Experimental results are reported on the L-star instability characteristics of three AP/composite propellants. The metal content of the propellants is 2, 16, and 16%. Chuffing, bulk mode oscillations, and time-independent combustion are observed with all three of these propellants. The stability boundary, defined as the boundary between time-independent and unstable combustion, is found to be well defined for two of the propellants in agreement with recognized trends available in the literature on other propellants. The frequency of bulk mode oscillations is presented as a function of the chamber characteristic length. One of the propellants tested has shown bulk mode instability at as high a pressure as 217 psia.

  8. Preliminary Results on the Experimental Investigation of the Structure Functions of Bound Nucleons

    SciTech Connect

    Bodek, Arie

    2015-09-01

    We present preliminary results on an experimental study of the nuclear modification of the longitudinal (σL) and transverse (σT) structure functions of nucleons bound in nuclear targets. The origin of these modifications (commonly referred as as the EMC effect) is not fully understood. Our measurements of R= σLT for nuclei (RA) and for deuterium (RD) indicate that nuclear modifications of the structure functions of bound nucleons are different for the longitudinal and transverse structure functions, and that contrary to expectation from several theoretical models, RA < RD.

  9. Theoretical versus experimental results for the rotordynamic coefficients of eccentric, smooth, gas annular seal annular gas seals

    NASA Technical Reports Server (NTRS)

    Childs, Dara W.; Alexander, Chis

    1994-01-01

    This viewgraph presentation presents the following results: (1) The analytical results overpredict the experimental results for the direct stiffness values and incorrectly predict increasing stiffness with decreasing pressure ratios. (2) Theory correctly predicts increasing cross-coupled stiffness, K(sub YX), with increasing eccentricity and inlet preswirl. (3) Direct damping, C(sub XX), underpredicts the experimental results, but the analytical results do correctly show that damping increases with increasing eccentricity. (4) The whirl frequency values predicted by theory are insensitive to changes in the static eccentricity ratio. Although these values match perfectly with the experimental results at 16,000 rpm, the results at the lower speed do not correspond. (5) Theoretical and experimental mass flow rates match at 5000 rpm, but at 16,000 rpm the theoretical results overpredict the experimental mass flow rates. (6) Theory correctly shows the linear pressure profiles and the associated entrance losses with the specified rotor positions.

  10. Reduction of FeO in smelting slags by solid carbon: Experimental results

    NASA Astrophysics Data System (ADS)

    Sarma, B.; Cramb, A. W.; Fruehan, R. J.

    1996-10-01

    The reduction of CaO-SiO2-Al2O3-FeO slags containing less than 10 wt pct FeO by solid carbonaceous materials such as graphite, coke, and coal char was investigated at reaction temperatures of 1400 °C to 1450 °C. The carbon monoxide evolution rate from the system was measured using stationary and rotating carbon rods, stationary horizontal carbon surfaces, and pinned stationary spheres as the reductants. The measured reaction rate ranged from 3.25 × 10-7 mol cm-2 s-1 at 2.1 pct FeO under static conditions to 3.6 × 10-6 mol cm-2 s-1 at 9.5 pct FeO for a rotating rod experiment. Visualization of the experiment using X-ray fluoroscopy showed that gas evolution from the reduction reaction caused the slag to foam during the experiment and that a gas film formed between the carbon surface and the slag at all times during experimentation. The reaction rate increased with increased slag FeO contents under all experimental conditions; however, this variation was not linear with FeO content. The reaction rate also increased with the rotation speed of the carbon rod at a given FeO content. A small increase in the reaction rate, at a given FeO content, was found when horizontal coke surfaces and coke spheres were used as the reductant as compared to graphite and coal char. The results of these experiments do not fit the traditional mass transfer correlations due to the evolution of gas during the experiment. The experimental results are consistent, however, with the hypothesis that liquid phase mass transfer of iron oxide is a major factor in the rate of reduction of iron oxide from slags by carbonaceous materials. In a second article, the individual rates of the possible limiting steps will be compared and a mixed control model will be used to explain the measured reaction rates.

  11. Preliminary Results of an Experimental Investigation of the Qu Superconducting Heat Pipe

    NASA Technical Reports Server (NTRS)

    Blackmon, James B.; Entrekin, Sean F.

    2006-01-01

    This note on preliminary results of our evaluation of the so-called Qu Tube is prompted in part by recent concerns expressed to the authors by some researchers regarding the performance characteristics of the superconducting, solid-state heat pipe as described in the patents, or on the company's websites. Briefly, the company's claims include: a new type of heat transfer mechanism that is a form of solid state thermal superconductivity, which results in an effective thermal conductivity of the order of tens of thousands of times that of an equivalent solid silver bar, or, tens to hundreds of times that of liquid - vapor heat pipes. The company's website also refers to tests conducted by Stanford Research Institute that substantiate these claims, but the report is apparently not publicly available. We are conducting an investigation of the Qu Tube under a NASA Grant, and in general find that these claims have merit, but our study is not yet complete. We present some of our preliminary results in part to show that it would not be imprudent to conduct such studies, especially for possible future applications requiring exceptional thermal management performance capabilities. Working with HiTek Services, we originally acquired several Qu Tubes, including 17" long, 5/16" diameter copper tubes, one that is 7 7/8" long, 3/16" diameter, and one that is 4" long, 1" diameter. We subjected the smaller tubes to various exploratory tests, including a transient test with electrical band heaters, boiling water tests, and a series of steady state tests with electrical band heaters heating one end with free convective cooling along the remainder of the length. All results indicate a very high thermal conductivity, but the length of these tubes limited our ability to obtain accurate data on temperature gradients, necessary to determine the effective thermal conductivity. We then acquired nine Qu Tubes that are 10' long, 5/16" diameter, and we have recently conducted initial tests

  12. Using leg muscles as shock absorbers: theoretical predictions and experimental results of drop landing performance.

    PubMed

    Minetti, A E; Ardigò, L P; Susta, D; Cotelli, F

    1998-12-01

    The use of muscles as power dissipators is investigated in this study, both from the modellistic and the experimental points of view. Theoretical predictions of the drop landing manoeuvre for a range of initial conditions have been obtained by accounting for the mechanical characteristics of knee extensor muscles, the limb geometry and assuming maximum neural activation. Resulting dynamics have been represented in the phase plane (vertical displacement versus speed) to better classify the damping performance. Predictions of safe landing in sedentary subjects were associated to dropping from a maximum (feet) height of 1.6-2.0 m (about 11 m on the moon). Athletes can extend up to 2.6-3.0 m, while for obese males (m = 100 kg, standard stature) the limit should reduce to 0.9-1.3 m. These results have been calculated by including in the model the estimated stiffness of the 'global elastic elements' acting below the squat position. Experimental landings from a height of 0.4, 0.7, 1.1 m (sedentary males (SM) and male (AM) and female (AF) athletes from the alpine ski national team) showed dynamics similar to the model predictions. While the peak power (for a drop height of about 0.7 m) was similar in SM and AF (AM shows a +40% increase, about 33 W/kg), AF stopped the downward movement after a time interval (0.219 +/- 0.030 s) from touch-down 20% significantly shorter than SM. Landing strategy and the effect of anatomical constraints are discussed in the paper. PMID:9857837

  13. Can laboratory tholins mimic the chemistry producing Titan's aerosols? A review in light of ACP experimental results

    NASA Astrophysics Data System (ADS)

    Coll, P.; Navarro-González, R.; Szopa, C.; Poch, O.; Ramírez, S. I.; Coscia, D.; Raulin, F.; Cabane, M.; Buch, A.; Israël, G.

    2013-03-01

    The first results obtained by the ACP experiment onboard Huygens probe revealed that the main products obtained after thermolysis of Titan's collected aerosols, were ammonia (NH3) and hydrogen cyanide (HCN). Titan's aerosols, and their laboratory analogues named tholins, have been the subject of experimental or theoretical studies during the last four decades. These studies have been mainly devoted to understanding their origin and formation mechanisms, their physical, chemical and optical properties, and their role in the radiative equilibrium of the satellite. Before the arrival of the Cassini-Huygens mission, the dense layer of aerosols hid many aspects of the satellite's surface and precious information about its composition. If Titan's aerosols have been in the eye and mind of planetary scientists during such a long time, it is not surprising that a literature survey displays a good quantity of papers on aerosol analogues. With aerosol analogues we mean any material produced in a terrestrial laboratory under conditions that try to represent those of Titan's atmosphere. We present here a study aimed to understand the particularities of aerosol analogues synthesized in different laboratories around the world in order to determine some of their most representative chemical fingerprints and in some cases, to perform a direct comparison of the volatiles produced after a thermal treatment done in conditions similar to the ones used by the ACP experiment. From the information collected, we propose a broad classification of aerosol analogues highlighting the materials that can be more representative of Titan's aerosols in terms of their content of organic volatiles. We identify the laboratory analogs that best suit the ACP results; such identification is of prime importance to correctly predict the optical properties of Titan's aerosol and to accurately estimate their contribution in radiative equilibrium models and/or to assess their role in chemical reactions of

  14. Lac Repressor Mediated DNA Looping: Monte Carlo Simulation of Constrained DNA Molecules Complemented with Current Experimental Results

    PubMed Central

    Biton, Yoav Y.; Kumar, Sandip; Dunlap, David; Swigon, David

    2014-01-01

    Tethered particle motion (TPM) experiments can be used to detect time-resolved loop formation in a single DNA molecule by measuring changes in the length of a DNA tether. Interpretation of such experiments is greatly aided by computer simulations of DNA looping which allow one to analyze the structure of the looped DNA and estimate DNA-protein binding constants specific for the loop formation process. We here present a new Monte Carlo scheme for accurate simulation of DNA configurations subject to geometric constraints and apply this method to Lac repressor mediated DNA looping, comparing the simulation results with new experimental data obtained by the TPM technique. Our simulations, taking into account the details of attachment of DNA ends and fluctuations of the looped subsegment of the DNA, reveal the origin of the double-peaked distribution of RMS values observed by TPM experiments by showing that the average RMS value for anti-parallel loop types is smaller than that of parallel loop types. The simulations also reveal that the looping probabilities for the anti-parallel loop types are significantly higher than those of the parallel loop types, even for loops of length 600 and 900 base pairs, and that the correct proportion between the heights of the peaks in the distribution can only be attained when loops with flexible Lac repressor conformation are taken into account. Comparison of the in silico and in vitro results yields estimates for the dissociation constants characterizing the binding affinity between O1 and Oid DNA operators and the dimeric arms of the Lac repressor. PMID:24800809

  15. Shuttle Damage/Repair from the Perspective of Hypersonic Boundary Layer Transition - Experimental Results

    NASA Technical Reports Server (NTRS)

    Horvath, Thomas J.; Berry, Scott A.; Merski, N. Ronald; Berger, Karen T.; Buck, Gregory M.; Liechty, Derek S.; Schneider, Steven P.

    2006-01-01

    An overview is provided of the experimental wind tunnel program conducted at the NASA Langley Research Center Aerothermodynamics Laboratory in support of an agency-wide effort to prepare the Shuttle Orbiter for Return-to-Flight. The effect of an isolated protuberance and an isolated rectangular cavity on hypersonic boundary layer transition onset on the windward surface of the Shuttle Orbiter has been experimentally characterized. These experimental studies were initiated to provide a protuberance and cavity effects database for developing hypersonic transition criteria to support on-orbit disposition of thermal protection system damage or repair. In addition, a synergistic experimental investigation was undertaken to assess the impact of an isolated mass-flow entrainment source (simulating pyrolysis/outgassing from a proposed tile repair material) on boundary layer transition. A brief review of the relevant literature regarding hypersonic boundary layer transition induced from cavities and localized mass addition from ablation is presented. Boundary layer transition results were obtained using 0.0075-scale Orbiter models with simulated tile damage (rectangular cavities) of varying length, width, and depth and simulated tile damage or repair (protuberances) of varying height. Cavity and mass addition effects were assessed at a fixed location (x/L = 0.3) along the model centerline in a region of near zero pressure gradient. Cavity length-to-depth ratio was systematically varied from 2.5 to 17.7 and length-to-width ratio of 1 to 8.5. Cavity depth-to-local boundary layer thickness ranged from 0.5 to 4.8. Protuberances were located at several sites along the centerline and port/starboard attachment lines along the chine and wing leading edge. Protuberance height-to-boundary layer thickness was varied from approximately 0.2 to 1.1. Global heat transfer images and heating distributions of the Orbiter windward surface using phosphor thermography were used to infer the

  16. Comparison Between Numerical and Experimental Results on Mechanical Stirrer and Bubbling in a Cylindrical Tank - 13047

    SciTech Connect

    Lima da Silva, M.; Sauvage, E.; Brun, P.; Gagnoud, A.; Fautrelle, Y.; Riva, R.

    2013-07-01

    The process of vitrification in a cold crucible heated by direct induction is used in the fusion of oxides. Its feature is the production of high-purity materials. The high-level of purity of the molten is achieved because this melting technique excludes the contamination of the charge by the crucible. The aim of the present paper is to analyze the hydrodynamic of the vitrification process by direct induction, with the focus in the effects associated with the interaction between the mechanical stirrer and bubbling. Considering the complexity of the analyzed system and the goal of the present work, we simplified the system by not taking into account the thermal and electromagnetic phenomena. Based in the concept of hydraulic similitude, we performed an experimental study and a numerical modeling of the simplified model. The results of these two studies were compared and showed a good agreement. The results presented in this paper in conjunction with the previous work contribute to a better understanding of the hydrodynamics effects resulting from the interaction between the mechanical stirrer and air bubbling in the cold crucible heated by direct induction. Further works will take into account thermal and electromagnetic phenomena in the presence of mechanical stirrer and air bubbling. (authors)

  17. Results of the NASA/General Electric Experimental Clean Combustor Program

    NASA Technical Reports Server (NTRS)

    Gleason, C. C.; Niedzwiecki, R. W.

    1976-01-01

    The NASA/General Electric Experimental Clean Combustor Program is a multi-year, major contract effort. Primary program objectives are the generation of technology for development of advanced commercial CTOL engines with lower exhaust emissions than current aircraft and, demonstrations of this technology in a full-scale CF6-50C engine in 1976. This paper describes pollution and performance goals, Phase I and II test results and Phase III hardware, pollution sampling techniques and test plans. Pollution results are presented in emission index and Environmental Protection Agency 1979 Standard Parameters (EPAP). Best results were obtained with a double annular combustor concept. This concept, which incorporates multistage burning, produced EPAP values extrapolated to CF6-50C engine conditions for CO, HC, and NOx of 3.3, 0.3 and 4.5, respectively. These represent respective CO, HC and NOx percentage reductions of 69, 93 and 42%, compared to current CF6-50 engine values. The combustor also met development engine performance requirements.

  18. Optimal placement of piezoelectric plates for active vibration control of gas turbine blades: experimental results

    NASA Astrophysics Data System (ADS)

    Botta, F.; Marx, N.; Gentili, S.; Schwingshackl, C. W.; Di Mare, L.; Cerri, G.; Dini, D.

    2012-04-01

    It is well known that the gas turbine blade vibrations can give rise to catastrophic failures and a reduction of the blades life because of fatigue related phenomena[1]-[3] . In last two decades, the adoption of piezoelectric elements, has received considerable attention by many researcher for its potential applicability to different areas of mechanical, aerospace, aeronautical and civil engineering. Recently, a number of studies of blades vibration control via piezoelectric plates and patches have been reported[4]-[6] . It was reported that the use of piezoelectric elements can be very effective in actively controlling vibrations. In one of their previous contributions[7] , the authors of the present manuscript studied a model to control the blade vibrations by piezoelectric elements and validated their results using a multi-physics finite elements package (COMSOL) and results from the literature. An optimal placement method of piezoelectric plate has been developed and applied to different loading scenarios for realistic configurations encountered in gas turbine blades. It has been demonstrated that the optimal placement depends on the spectrum of the load, so that segmented piezoelectric patches have been considered and, for different loads, an optimal combination of sequential and/or parallel actuation and control of the segments has been studied. In this paper, an experimental investigation carried out by the authors using a simplified beam configuration is reported and discussed. The test results obtained by the investigators are then compared with the numerical predictions [7] .

  19. Experimental results of the influence of ionic strength in liquid environment on fiber life

    NASA Astrophysics Data System (ADS)

    Overgaard, Jette V.

    1996-01-01

    Stress free corrosion such as chemical dissolution of silica optical fibers is normally assumed to be a pure pH dependent reaction. In our investigation we have found that it is not only the pH values that influence the lifetime of the fiber in water, but also the ionic strength of the water in contact with the fiber. We have seen that the lifetime of the normal dual coated fibers is severely reduced in seawater compared to the lifetime in deionized water. Carbon coated fibers show better results in these harsh conditions; but the experiments also demonstrate that the carbon coated fibers begin to fail before they have had a sufficient lifetime. A chemical explanation of the results, based on dissolution of glass in water and influence from the ions in question, is given. In this paper, experimental results from long term static fatigue tests on fibers in different liquid environments is shown. In the laboratory we have samples still living after almost four years in different environments. We have buffered water at pH values from 3 to 11, artificial seawater and deionized water. The fibers in the tests are both commercially available dual coated and carbon coated fibers and carbon coated test fibers.

  20. Large Fluorescence Enhancements of Fluorophore Ensembles with Multilayer Plasmonic Substrates: Comparison of Theory and Experimental Results

    PubMed Central

    Szmacinski, Henryk; Badugu, Ramachandram; Mahdavi, Farhad; Blair, Steve; Lakowicz, Joseph R.

    2013-01-01

    Multilayer substrates consisting of a glass slide, silver mirror, silica layer, and silver nanoparticles were fabricated using magnetron sputtering. This new geometry of substrates with backplane mirror and dielectric photonic cavity produced large average fluorescence enhancements up to 190-fold. Fluorescence enhancements of five fluorescent probes were measured over the broad spectral range from 470 to 800 nm. Fluorescent probes were streptavidin conjugates attached to the substrate surface through a layer of biotinylated bovine serum albumin. The protein layers represent a common surface modification for surface-based bioassays such as immunoassays or molecular diagnostic assays. We found that optimal enhancement is dependent on the thickness of the dielectric layer separating the silver mirror and the silver nanoparticles and on the spectral range. We performed numerical calculations for enhancement in both the excitation and emission using finite element method (FEM) the results of which were in qualitative agreement with the experimental results. The described method for fabrication multilayered substrates and the results obtained with protein layers demonstrate great potential for the design of simple and ultrasensitive fluorometric bioassays with large optical amplifications compared to the standard approaches of enzyme-based bioassays with dielectric surfaces. PMID:24163712

  1. Theoretical and experimental examination of recovery in the context of trueness of analytical results.

    PubMed

    Stafiński, Maciej; Wieczorek, Marcin; Janicki, Piotr; Kościelniak, Paweł

    2012-07-15

    In the report of the International Union of Pure and Applied Chemistry (IUPAC) estimation of analyte recovery (RV) is recommended as one of the ways for assessment of trueness of analytical results. RV is usually estimated with the use of samples spiked with known amount of analyte. However, neither the IUPAC guidelines, nor the available literature take into consideration various effects of different nature that may occur along the sample preparation steps prior and during measurements. Hence, in this work the attempt was made to classify these effects and to evaluate their influence on the analyte recovery. For this purpose a mathematical model has been developed, enabling to judge usefulness of the recovery test in objective estimation of trueness, and the results predicted by the model were checked experimentally. Trueness was estimated on the basis of analytical results obtained by both interpolative and extrapolative ways. The experiments were performed with the use of a dedicated flow injection system coupled to UV/VIS spectrometer and covered determination of chromium(III) as chromium(III) nitrate at a wavelength of 590nm. PMID:22817925

  2. An experimental investigation of multi-element airfoil ice accretion and resulting performance degradation

    NASA Technical Reports Server (NTRS)

    Potapczuk, Mark G.; Berkowitz, Brian M.

    1989-01-01

    An investigation of the ice accretion pattern and performance characteristics of a multi-element airfoil was undertaken in the NASA Lewis 6- by 9-Foot Icing Research Tunnel. Several configurations of main airfoil, slat, and flaps were employed to examine the effects of ice accretion and provide further experimental information for code validation purposes. The text matrix consisted of glaze, rime, and mixed icing conditions. Airflow and icing cloud conditions were set to correspond to those typical of the operating environment anticipated tor a commercial transport vehicle. Results obtained included ice profile tracings, photographs of the ice accretions, and force balance measurements obtained both during the accretion process and in a post-accretion evaluation over a range of angles of attack. The tracings and photographs indicated significant accretions on the slat leading edge, in gaps between slat or flaps and the main wing, on the flap leading-edge surfaces, and on flap lower surfaces. Force measurments indicate the possibility of severe performance degradation, especially near C sub Lmax, for both light and heavy ice accretion and performance analysis codes presently in use. The LEWICE code was used to evaluate the ice accretion shape developed during one of the rime ice tests. The actual ice shape was then evaluated, using a Navier-Strokes code, for changes in performance characteristics. These predicted results were compared to the measured results and indicate very good agreement.

  3. Accurate Evaluation of Quantum Integrals

    NASA Technical Reports Server (NTRS)

    Galant, David C.; Goorvitch, D.

    1994-01-01

    Combining an appropriate finite difference method with Richardson's extrapolation results in a simple, highly accurate numerical method for solving a Schr\\"{o}dinger's equation. Important results are that error estimates are provided, and that one can extrapolate expectation values rather than the wavefunctions to obtain highly accurate expectation values. We discuss the eigenvalues, the error growth in repeated Richardson's extrapolation, and show that the expectation values calculated on a crude mesh can be extrapolated to obtain expectation values of high accuracy.

  4. Accurate quantum chemical calculations

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Taylor, Peter R.

    1989-01-01

    An important goal of quantum chemical calculations is to provide an understanding of chemical bonding and molecular electronic structure. A second goal, the prediction of energy differences to chemical accuracy, has been much harder to attain. First, the computational resources required to achieve such accuracy are very large, and second, it is not straightforward to demonstrate that an apparently accurate result, in terms of agreement with experiment, does not result from a cancellation of errors. Recent advances in electronic structure methodology, coupled with the power of vector supercomputers, have made it possible to solve a number of electronic structure problems exactly using the full configuration interaction (FCI) method within a subspace of the complete Hilbert space. These exact results can be used to benchmark approximate techniques that are applicable to a wider range of chemical and physical problems. The methodology of many-electron quantum chemistry is reviewed. Methods are considered in detail for performing FCI calculations. The application of FCI methods to several three-electron problems in molecular physics are discussed. A number of benchmark applications of FCI wave functions are described. Atomic basis sets and the development of improved methods for handling very large basis sets are discussed: these are then applied to a number of chemical and spectroscopic problems; to transition metals; and to problems involving potential energy surfaces. Although the experiences described give considerable grounds for optimism about the general ability to perform accurate calculations, there are several problems that have proved less tractable, at least with current computer resources, and these and possible solutions are discussed.

  5. A stereo triangulation system for structural identification: Analytical and experimental results

    NASA Technical Reports Server (NTRS)

    Junkins, J. L.; James, G. H., III; Pollock, T. C.; Rahman, Z. H.

    1988-01-01

    , and have established conclusively the feasibility and desirability of this approach. We discuss, in summary, recent advances in analog and digital video processing methodology, actuation methods, and bring them to bear on the structural identification problem. We include a brief discussion of our experimental hardware and some recent experimental results which support the practical feasibility of this structural vibration sensing approach.

  6. Phase-space analysis and experimental results for secondary focusing at X-ray beamlines

    SciTech Connect

    Huang, Rong; Meron, Mati; Kujala, Naresh; Barrea, Raul A.

    2011-11-17

    Micro-focusing optical devices at synchrotron beamlines usually have a limited acceptance, but more flux can be intercepted if such optics are used to focus secondary sources created by the primary optics. Flux throughput can be maximized by placing the secondary focusing optics close to or exactly at the secondary source position. However, standard methods of beamline optics analysis, such as the lens equation or matching the mirror surface to an ellipse, work poorly when the source-to-optics distance is very short. In this paper the general characteristics of the focusing of beams with Gaussian profiles by a 'thin lens' are analysed under the paraxial approximation in phase space, concluding that the focusing of a beam with a short source-to-optics distance is distinct from imaging the source; slope errors are successfully included in all the formulas so that they can be used to calculate beamline focusing with good accuracy. A method is also introduced to use the thin-lens result to analyse the micro-focusing produced by an elliptically bent trapezoid-shaped Kirkpatrick-Baez mirror. The results of this analysis are in good agreement with ray-tracing simulations and are confirmed by the experimental results of the secondary focusing at the 18-ID Bio-CAT beamline (at the APS). The result of secondary focusing carried out at 18-ID using a single-bounce capillary can also be explained using this phase-space analysis. A discussion of the secondary focusing results is presented at the end of this paper.

  7. Synthesizing large-scale pyroclastic flows: Experimental design, scaling, and first results from PELE

    NASA Astrophysics Data System (ADS)

    Lube, G.; Breard, E. C. P.; Cronin, S. J.; Jones, J.

    2015-03-01

    Pyroclastic flow eruption large-scale experiment (PELE) is a large-scale facility for experimental studies of pyroclastic density currents (PDCs). It is used to generate high-energy currents involving 500-6500 m3 natural volcanic material and air that achieve velocities of 7-30 m s-1, flow thicknesses of 2-4.5 m, and runouts of >35 m. The experimental PDCs are synthesized by a controlled "eruption column collapse" of ash-lapilli suspensions onto an instrumented channel. The first set of experiments are documented here and used to elucidate the main flow regimes that influence PDC dynamic structure. Four phases are identified: (1) mixture acceleration during eruption column collapse, (2) column-slope impact, (3) PDC generation, and (4) ash cloud diffusion. The currents produced are fully turbulent flows and scale well to natural PDCs including small to large scales of turbulent transport. PELE is capable of generating short, pulsed, and sustained currents over periods of several tens of seconds, and dilute surge-like PDCs through to highly concentrated pyroclastic flow-like currents. The surge-like variants develop a basal <0.05 m thick regime of saltating/rolling particles and shifting sand waves, capped by a 2.5-4.5 m thick, turbulent suspension that grades upward to lower particle concentrations. Resulting deposits include stratified dunes, wavy and planar laminated beds, and thin ash cloud fall layers. Concentrated currents segregate into a dense basal underflow of <0.6 m thickness that remains aerated. This is capped by an upper ash cloud surge (1.5-3 m thick) with 100 to 10-4 vol % particles. Their deposits include stratified, massive, normally and reversely graded beds, lobate fronts, and laterally extensive veneer facies beyond channel margins.

  8. Responses of Tundra Ecosystems to Environmental Change: Observational and Experimental Results

    NASA Astrophysics Data System (ADS)

    Henry, G. H.

    2004-05-01

    Evidence of environmental changes due to human-enhanced climate warming continues to accumulate from polar regions. Responses in tundra and taiga ecosystems to climate changes have been variable because of the wide range in process response rates, from metabolic processes to adjustments in ecosystem carbon balance, and the variability in environmental settings across local to regional scales. For example, strong increases in rates of plant growth and changes in species composition and abundance have been observed in parts of the Low Arctic, but very little change has been measured in high arctic tundra. A dramatic increase in the cover of deciduous shrubs in areas of the western North American Arctic is predicted to result in positive feedbacks to soil temperature, through increased surface roughness and snow depth, and to atmospheric heating by reducing albedo. Increased shrub cover has also been found in long-term experimental warming studies conducted throughout the tundra biome as part of the International Tundra Experiment (ITEX). Warming is also affecting the carbon balance of tundra and taiga, which hold 25% of the soil carbon of global terrestrial ecosystems. However, trajectories of these changes are largely unknown for most northern systems, and differ because of initial conditions of the carbon and nutrient economy. Over the longer-term, the positive increases in plant growth may be constrained by negative feedbacks to nutrient cycling, as increases in C:N ratios of plant litter slow the release of nitrogen to soils. However, nitrogen availability has been shown to increase in response to short-term warming. In this presentation, I will review the responses of tundra ecosystems to climate variability and change, both through observational and experimental studies.

  9. Dynamics of Dual Prism Adaptation: Relating Novel Experimental Results to a Minimalistic Neural Model

    PubMed Central

    Arévalo, Orlando; Bornschlegl, Mona A.; Eberhardt, Sven; Ernst, Udo; Pawelzik, Klaus; Fahle, Manfred

    2013-01-01

    In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo–motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements (‘dual–adaptation’). A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual–adaptation be faster if switches (‘phase changes’) between the environments occur more frequently? We investigated the dynamics of dual–adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo–motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual–adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual–adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of

  10. Beryllium metal I. experimental results on acute oral toxicity, local skin and eye effects, and genotoxicity.

    PubMed

    Strupp, Christian

    2011-01-01

    The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral

  11. Dynamics of dual prism adaptation: relating novel experimental results to a minimalistic neural model.

    PubMed

    Arévalo, Orlando; Bornschlegl, Mona A; Eberhardt, Sven; Ernst, Udo; Pawelzik, Klaus; Fahle, Manfred

    2013-01-01

    In everyday life, humans interact with a dynamic environment often requiring rapid adaptation of visual perception and motor control. In particular, new visuo-motor mappings must be learned while old skills have to be kept, such that after adaptation, subjects may be able to quickly change between two different modes of generating movements ('dual-adaptation'). A fundamental question is how the adaptation schedule determines the acquisition speed of new skills. Given a fixed number of movements in two different environments, will dual-adaptation be faster if switches ('phase changes') between the environments occur more frequently? We investigated the dynamics of dual-adaptation under different training schedules in a virtual pointing experiment. Surprisingly, we found that acquisition speed of dual visuo-motor mappings in a pointing task is largely independent of the number of phase changes. Next, we studied the neuronal mechanisms underlying this result and other key phenomena of dual-adaptation by relating model simulations to experimental data. We propose a simple and yet biologically plausible neural model consisting of a spatial mapping from an input layer to a pointing angle which is subjected to a global gain modulation. Adaptation is performed by reinforcement learning on the model parameters. Despite its simplicity, the model provides a unifying account for a broad range of experimental data: It quantitatively reproduced the learning rates in dual-adaptation experiments for both direct effect, i.e. adaptation to prisms, and aftereffect, i.e. behavior after removal of prisms, and their independence on the number of phase changes. Several other phenomena, e.g. initial pointing errors that are far smaller than the induced optical shift, were also captured. Moreover, the underlying mechanisms, a local adaptation of a spatial mapping and a global adaptation of a gain factor, explained asymmetric spatial transfer and generalization of prism adaptation, as

  12. Beryllium Metal I. Experimental Results on Acute Oral Toxicity, Local Skin and Eye Effects, and Genotoxicity

    PubMed Central

    Strupp, Christian

    2011-01-01

    The toxicity of soluble metal compounds is often different from that of the parent metal. Since no reliable data on acute toxicity, local effects, and mutagenicity of beryllium metal have ever been generated, beryllium metal powder was tested according to the respective Organisation for Economical Co-Operation and Development (OECD) guidelines. Acute oral toxicity of beryllium metal was investigated in rats and local effects on skin and eye in rabbits. Skin-sensitizing properties were investigated in guinea pigs (maximization method). Basic knowledge about systemic bioavailability is important for the design of genotoxicity tests on poorly soluble substances. Therefore, it was necessary to experimentally compare the capacities of beryllium chloride and beryllium metal to form ions under simulated human lung conditions. Solubility of beryllium metal in artificial lung fluid was low, while solubility in artificial lysosomal fluid was moderate. Beryllium chloride dissolution kinetics were largely different, and thus, metal extracts were used in the in vitro genotoxicity tests. Genotoxicity was investigated in vitro in a bacterial reverse mutagenicity assay, a mammalian cell gene mutation assay, a mammalian cell chromosome aberration assay, and an unscheduled DNA synthesis (UDS) assay. In addition, cell transformation was tested in a Syrian hamster embryo cell assay, and potential inhibition of DNA repair was tested by modification of the UDS assay. Beryllium metal was found not to be mutagenic or clastogenic based on the experimental in vitro results. Furthermore, treatment with beryllium metal extracts did not induce DNA repair synthesis, indicative of no DNA-damaging potential of beryllium metal. A cell-transforming potential and a tendency to inhibit DNA repair when the cell is severely damaged by an external stimulus were observed. Beryllium metal was also found not to be a skin or eye irritant, not to be a skin sensitizer, and not to have relevant acute oral

  13. Not so simple: a quasi-experimental study of how researchers adjudicate genetic research results

    PubMed Central

    Hayeems, Robin Zoe; Miller, Fiona Alice; Li, Li; Bytautas, Jessica Peace

    2011-01-01

    Ethicists contend that researchers are obliged to report genetic research findings to individual study participants when they are clinically significant, that is, when they are clinically useful or personally meaningful to participants. Yet whether such standards are well understood and can be consistently applied remains unknown. We conducted an international, cross-sectional survey of cystic fibrosis (CF) and autism genetics researchers using a quasi-experimental design to explore factors influencing researchers' judgments. Eighty percent of researchers agreed, in principle, that clinically significant findings should be reported to individual participants. Yet judgments about when a specific finding was considered clinically significant or warranted reporting varied by scientific factors (replication, robustness, intentionality, and disease context), capacity of the research team to explain the results, and type of research ethics guidance. Further, judgments were influenced by the researchers' disease community (autism or CF), their primary role (clinical, molecular, statistical) and their beliefs regarding a general reporting obligation. In sum, judgments about the clinical significance of genetic research results, and about whether they should be reported, are influenced by scientific parameters as well as contextual factors related to the specific research project and the individual researcher. These findings call into question the assumption that the conditions under which an obligation to disclose arises are uniformly understood and actionable. Adjudicating the clinical readiness of provisional data may be a responsibility better suited to evaluative experts at arms' length of the provisional data in question, rather than a responsibility imposed upon researchers themselves. PMID:21407262

  14. Quantitative Assessment of the CCMC's Experimental Real-time SWMF-Geospace Results

    NASA Astrophysics Data System (ADS)

    Liemohn, Michael; Ganushkina, Natalia; De Zeeuw, Darren; Welling, Daniel; Toth, Gabor; Ilie, Raluca; Gombosi, Tamas; van der Holst, Bart; Kuznetsova, Maria; Maddox, Marlo; Rastaetter, Lutz

    2016-04-01

    Experimental real-time simulations of the Space Weather Modeling Framework (SWMF) are conducted at the Community Coordinated Modeling Center (CCMC), with results available there (http://ccmc.gsfc.nasa.gov/realtime.php), through the CCMC Integrated Space Weather Analysis (iSWA) site (http://iswa.ccmc.gsfc.nasa.gov/IswaSystemWebApp/), and the Michigan SWMF site (http://csem.engin.umich.edu/realtime). Presently, two configurations of the SWMF are running in real time at CCMC, both focusing on the geospace modules, using the BATS-R-US magnetohydrodynamic model, the Ridley Ionosphere Model, and with and without the Rice Convection Model for inner magnetospheric drift physics. While both have been running for several years, nearly continuous results are available since July 2015. Dst from the model output is compared against the Kyoto real-time Dst, in particular the daily minimum value of Dst to quantify the ability of the model to capture storms. Contingency tables are presented, showing that the run with the inner magnetosphere model is much better at reproducing storm-time values. For disturbances with a minimum Dst lower than -50 nT, this version yields a probability of event detection of 0.86 and a Heidke Skill Score of 0.60. In the other version of the SWMF, without the inner magnetospheric module included, the modeled Dst never dropped below -50 nT during the examined epoch.

  15. Experimental Results for Temporally Overlapping Pulses from Quantel EverGreen 200 Laser

    NASA Technical Reports Server (NTRS)

    Watkins, A. Neal

    2013-01-01

    This report will detail the experimental results and observations obtained while investigating the feasibility of temporally overlapping the two laser pulses from a Quantel EverGreen 200 Laser. This laser was specifically designed for Particle Imaging Velocimetry (PIV) applications and operate by emitting two 532 nm laser pulses that are seperated by an adjustable finite time (typically on the order of ten to hundreds of microseconds). However, the use of this model laser has found recent application for Pressure Sensitive Paint (PSP) testing, especially for rotorcraft research. For this testing, it is desired to only use one laser pulse. While this is easily done by only firing one of the laser heads, more excitation energy could conceivably be had if both laser heads are fired with zero pulse separation. In addition, recently large field-of-view PIV measurements have become possible and need ever increasing laser power to illuminate the larger areas. For this work, two different methods of timing the laser are investigated using both a traditional power meter to monitor laser power as well as a fast photodiode to determine pulse separation. The results are presented here as well as some simple implications for PIV experiments using these methods.

  16. A comparison of experimental results of soot production in laminar premixed flames

    NASA Astrophysics Data System (ADS)

    Caetano, Nattan R.; Soares, Diego; Nunes, Roger P.; Pereira, Fernando M.; Smith Schneider, Paulo; Vielmo, Horácio A.; van der Laan, Flávio Tadeu

    2015-05-01

    Soot emission has been the focus of numerous studies due to the numerous applications in industry, as well as the harmful effects caused to the environment. Thus, the purpose of this work is to analyze the soot formation in a flat flame burner using premixed compressed natural gas and air, where these quasi-adiabatic flames have one-dimensional characteristics. The measurements were performed applying the light extinction technique. The air/fuel equivalence ratiowas varied to assess the soot volume fractions for different flame configurations. Soot production along the flamewas also analyzed by measurements at different heights in relation to the burner surface. Results indicate that soot volume fraction increases with the equivalence ratio. The higher regions of the flamewere analyzed in order to map the soot distribution on these flames. The results are incorporated into the experimental database for measurement techniques calibration and for computational models validation of soot formation in methane premixed laminar flames, where the equivalence ratio ranging from 1.5 up to 8.

  17. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    NASA Astrophysics Data System (ADS)

    Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong; Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun; Zhou, Xiu-Wen; Yang, Yi

    2015-07-01

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ˜10 MA, 70 ns rise-time (10%-90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132-300 tungsten wires with 5-10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (˜50 TW) and total radiated energy (˜500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

  18. Preliminary experimental results of tungsten wire-array Z-pinches on primary test stand

    SciTech Connect

    Huang, Xian-Bin; Zhou, Shao-Tong; Dan, Jia-Kun; Ren, Xiao-Dong Wang, Kun-Lun; Zhang, Si-Qun; Li, Jing; Xu, Qiang; Cai, Hong-Chun; Duan, Shu-Chao; Ouyang, Kai; Chen, Guang-Hua; Ji, Ce; Wei, Bing; Feng, Shu-Ping; Wang, Meng; Xie, Wei-Ping; Deng, Jian-Jun; Zhou, Xiu-Wen; Yang, Yi

    2015-07-15

    The Primary Test Stand (PTS) developed at the China Academy of Engineering Physics is a 20 TW pulsed power driver, which can deliver a ∼10 MA, 70 ns rise-time (10%–90%) current to a short-circuit load and has important applications in Z-pinch driven inertial confinement fusion and high energy density physics. Preliminary results of tungsten wire-array Z-pinch experiments on PTS are presented. The load geometries investigated include 15-mm-tall cylindrical single and nested arrays with diameter ranging from 13 mm to 30 mm, consisting of 132–300 tungsten wires with 5–10 μm in diameter. Multiple diagnostics were fielded to characterize the x-ray radiation from wire-array Z pinches. The x-ray peak power (∼50 TW) and total radiated energy (∼500 kJ) were obtained from a single 20-mm-diam array with 80-ns stagnation time. The highest x-ray peak power up to 80 TW with 2.4 ns FWHM was achieved by using a nested array with 20-mm outer diameter, and the total x-ray energy from the nested array is comparable to that of single array. Implosion velocity estimated from the time-resolved image measurement exceeds 30 cm/μs. The detailed experimental results and other findings are presented and discussed.

  19. Using the Viking biology experimental results to obtain chemical information about Martian regolith

    NASA Technical Reports Server (NTRS)

    Plumb, Robert C.

    1992-01-01

    Although initially formulated as biology experiments, most of the results produced by the Viking Labeled Release (LR), Gas Exchange (GEX), and Pyrolytic Release (PR) experiments have been reproduced by chemical means. The experiments do not need more study as 'biological' phenomena, but they do deserve much more careful consideration from a chemical viewpoint. They are the only 'wet-chemical' experiments that scientists have performed on another planet, but they have not found very general use as sources of scientific information. There is a large set of potentially useful chemical observations, e.g., the three resolvable and precisely measured kinetic components of the release of C-14-labeled gases, the thermal sensitivity and magnitudes of the oxidation reaction(s) of the LR experiments, the kinetics and magnitude of the O2 and CO2 release of the GEX experiments, the thermal sensitivity of the GEX results, the differences between the thermal sensitivity of the GEX and the thermal sensitivity of the LR responses, and the kinetics and magnitudes of the LR successive injection reabsorption effect. It should be possible to test many chemical aspects of hypothetical martian phenomena in experiments using the biology experimental configurations and derive much valuable information by comparisons with the Viking observations.

  20. COMPARISON OF EXPERIMENTAL RESULTS TO CFD MODELS FOR BLENDING IN A TANK USING DUAL OPPOSING JETS

    SciTech Connect

    Leishear, R.

    2011-08-07

    Research has been completed in a pilot scale, eight foot diameter tank to investigate blending, using a pump with dual opposing jets. The jets re-circulate fluids in the tank to promote blending when fluids are added to the tank. Different jet diameters and different horizontal and vertical orientations of the jets were investigated. In all, eighty five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of several miles of two inch diameter, serpentine, vertical cooling coils below the liquid surface for a full scale, 1.3 million gallon, liquid radioactive waste storage tank. Two types of tests were performed. One type of test used a tracer fluid, which was homogeneously blended into solution. Data were statistically evaluated to determine blending times for solutions of different density and viscosity, and the blending times were successfully compared to computational fluid dynamics (CFD) models. The other type of test blended solutions of different viscosity. For example, in one test a half tank of water was added to a half tank of a more viscous, concentrated salt solution. In this case, the fluid mechanics of the blending process was noted to significantly change due to stratification of fluids. CFD models for stratification were not investigated. This paper is the fourth in a series of papers resulting from this research (Leishear, et.al. [1- 4]), and this paper documents final test results, statistical analysis of the data, a comparison of experimental results to CFD models, and scale-up of the results to a full scale tank.

  1. Thermodiffusion in concentrated ferrofluids: Experimental and numerical results on magnetic thermodiffusion

    SciTech Connect

    Sprenger, Lisa Lange, Adrian; Odenbach, Stefan

    2014-02-15

    Ferrofluids consist of magnetic nanoparticles dispersed in a carrier liquid. Their strong thermodiffusive behaviour, characterised by the Soret coefficient, coupled with the dependency of the fluid's parameters on magnetic fields is dealt with in this work. It is known from former experimental investigations on the one hand that the Soret coefficient itself is magnetic field dependent and on the other hand that the accuracy of the coefficient's experimental determination highly depends on the volume concentration of the fluid. The thermally driven separation of particles and carrier liquid is carried out with a concentrated ferrofluid (φ = 0.087) in a horizontal thermodiffusion cell and is compared to equally detected former measurement data. The temperature gradient (1 K/mm) is applied perpendicular to the separation layer. The magnetic field is either applied parallel or perpendicular to the temperature difference. For three different magnetic field strengths (40 kA/m, 100 kA/m, 320 kA/m) the diffusive separation is detected. It reveals a sign change of the Soret coefficient with rising field strength for both field directions which stands for a change in the direction of motion of the particles. This behaviour contradicts former experimental results with a dilute magnetic fluid, in which a change in the coefficient's sign could only be detected for the parallel setup. An anisotropic behaviour in the current data is measured referring to the intensity of the separation being more intense in the perpendicular position of the magnetic field: S{sub T‖} = −0.152 K{sup −1} and S{sub T⊥} = −0.257 K{sup −1} at H = 320 kA/m. The ferrofluiddynamics-theory (FFD-theory) describes the thermodiffusive processes thermodynamically and a numerical simulation of the fluid's separation depending on the two transport parameters ξ{sub ‖} and ξ{sub ⊥} used within the FFD-theory can be implemented. In the case of a parallel aligned magnetic field, the parameter can

  2. NNLOPS accurate associated HW production

    NASA Astrophysics Data System (ADS)

    Astill, William; Bizon, Wojciech; Re, Emanuele; Zanderighi, Giulia

    2016-06-01

    We present a next-to-next-to-leading order accurate description of associated HW production consistently matched to a parton shower. The method is based on reweighting events obtained with the HW plus one jet NLO accurate calculation implemented in POWHEG, extended with the MiNLO procedure, to reproduce NNLO accurate Born distributions. Since the Born kinematics is more complex than the cases treated before, we use a parametrization of the Collins-Soper angles to reduce the number of variables required for the reweighting. We present phenomenological results at 13 TeV, with cuts suggested by the Higgs Cross section Working Group.

  3. Modal characterization of the ASCIE segmented optics testbed: New algorithms and experimental results

    NASA Technical Reports Server (NTRS)

    Carrier, Alain C.; Aubrun, Jean-Noel

    1993-01-01

    New frequency response measurement procedures, on-line modal tuning techniques, and off-line modal identification algorithms are developed and applied to the modal identification of the Advanced Structures/Controls Integrated Experiment (ASCIE), a generic segmented optics telescope test-bed representative of future complex space structures. The frequency response measurement procedure uses all the actuators simultaneously to excite the structure and all the sensors to measure the structural response so that all the transfer functions are measured simultaneously. Structural responses to sinusoidal excitations are measured and analyzed to calculate spectral responses. The spectral responses in turn are analyzed as the spectral data become available and, which is new, the results are used to maintain high quality measurements. Data acquisition, processing, and checking procedures are fully automated. As the acquisition of the frequency response progresses, an on-line algorithm keeps track of the actuator force distribution that maximizes the structural response to automatically tune to a structural mode when approaching a resonant frequency. This tuning is insensitive to delays, ill-conditioning, and nonproportional damping. Experimental results show that is useful for modal surveys even in high modal density regions. For thorough modeling, a constructive procedure is proposed to identify the dynamics of a complex system from its frequency response with the minimization of a least-squares cost function as a desirable objective. This procedure relies on off-line modal separation algorithms to extract modal information and on least-squares parameter subset optimization to combine the modal results and globally fit the modal parameters to the measured data. The modal separation algorithms resolved modal density of 5 modes/Hz in the ASCIE experiment. They promise to be useful in many challenging applications.

  4. Cessation of environmentally-assisted cracking in a low-alloy steel: Experimental results

    SciTech Connect

    Li, Y.Y.

    1997-01-01

    The presence of dissolved metallurgical sulfides in pressure vessel and piping steels has been linked to Environmentally-Assisted Cracking (EAC), a phenomenon observed in laboratory tests that results in fatigue crack growth rates as high as 100 times that in air. Previous experimental and analytical work based on diffusion as the mass transport process has shown that surface cracks that are initially clean of sulfides will not initiate EAC in most applications. This is because the average crack tip velocity would not be sufficiently high to expose enough metallurgical sulfides per unit time and produce the sulfide concentration required for EAC. However, there is a potential concern for the case of a relatively large embedded crack breaking through to the wetted surface. Such a crack would not be initially clean of sulfides, and EAC could initiate. This paper presents the results of a series of experiments conducted on two heats of an EAC susceptible, high-sulfur, low-alloy steel in 243{degrees}C low-oxygen water to further study the phenomenon of EAC persistence at low crack tip velocities. A load cycle profile that incorporated a significant load dwell period at minimum load was used. In one experiment, the fatigue cycling history was such that relatively high crack tip velocities at the start of the experiment produced a persistent case of EAC even when crack tip velocities were later reduced to levels below the EAC initiation velocity. The other series of experiments used initial crack tip velocities that were much lower and probably more realistic. Air precracking of the compact tension specimens produced an initial inventory of undissolved sulfides on the crack flanks that directly simulates the array of sulfides expected from the breakthrough of an embedded crack. In all cases, results showed EAC ceased after several hundred hours of cycling.

  5. Experimental Results from the Thermal Energy Storage-2 (TES-2) Flight Experiment

    NASA Technical Reports Server (NTRS)

    Tolbert, Carol

    2000-01-01

    Thermal Energy Storage-2 (TES-2) is a flight experiment that flew on the Space Shuttle Endeavour (STS-72), in January 1996. TES-2 originally flew with TES-1 as part of the OAST-2 Hitchhiker payload on the Space Shuttle Columbia (STS-62) in early 1994. The two experiments, TES-1 and TES-2 were identical except for the fluoride salts to be characterized. TES-1 provided data on lithium fluoride (LiF), TES-2 provided data on a fluoride eutectic (LiF/CaF2). Each experiment was a complex autonomous payload in a Get-Away-Special payload canister. TES-1 operated flawlessly for 22 hr. Results were reported in a paper entitled, Effect of Microgravity on Materials Undergoing Melting and Freezing-The TES Experiment, by David Namkoong et al. A software failure in TES-2 caused its shutdown after 4 sec of operation. TES-1 and 2 were the first experiments in a four experiment suite designed to provide data for understanding the long duration microgravity behavior of thermal energy storage salts that undergo repeated melting and freezing. Such data have never been obtained before and have direct application for the development of space-based solar dynamic (SD) power systems. These power systems will store energy in a thermal energy salt such as lithium fluoride or a eutectic of lithium fluoride/calcium difluoride. The stored energy is extracted during the shade portion of the orbit. This enables the solar dynamic power system to provide constant electrical power over the entire orbit. Analytical computer codes were developed for predicting performance of a space-based solar dynamic power system. Experimental verification of the analytical predictions were needed prior to using the analytical results for future space power design applications. The four TES flight experiments were to be used to obtain the needed experimental data. This paper will address the flight results from the first and second experiments, TES-1 and 2, in comparison to the predicted results from the Thermal

  6. Active behavior of abdominal wall muscles: Experimental results and numerical model formulation.

    PubMed

    Grasa, J; Sierra, M; Lauzeral, N; Muñoz, M J; Miana-Mena, F J; Calvo, B

    2016-08-01

    In the present study a computational finite element technique is proposed to simulate the mechanical response of muscles in the abdominal wall. This technique considers the active behavior of the tissue taking into account both collagen and muscle fiber directions. In an attempt to obtain the computational response as close as possible to real muscles, the parameters needed to adjust the mathematical formulation were determined from in vitro experimental tests. Experiments were conducted on male New Zealand White rabbits (2047±34g) and the active properties of three different muscles: Rectus Abdominis, External Oblique and multi-layered samples formed by three muscles (External Oblique, Internal Oblique, and Transversus Abdominis) were characterized. The parameters obtained for each muscle were incorporated into a finite strain formulation to simulate active behavior of muscles incorporating the anisotropy of the tissue. The results show the potential of the model to predict the anisotropic behavior of the tissue associated to fibers and how this influences on the strain, stress and generated force during an isometric contraction. PMID:27111629

  7. The dependence of ultrasonic backscatter on trabecular thickness in human calcaneus: theoretical and experimental results.

    PubMed

    Wear, Keith A; Laib, Andres

    2003-08-01

    Trabecular thickness within cancellous bone is an important determinant of osteoporotic fracture risk. Noninvasive assessment of trabecular thickness potentially could yield useful diagnostic information. Faran's theory of elastic scattering from a cylindrical object immersed in a fluid has been used to predict the dependence of ultrasonic backscatter on trabecular thickness. The theory predicts that, in the range of morphological and material properties expected for trabecular bone, the backscatter coefficient at 500 kHz should be approximately proportional to trabecular thickness to the power of 2.9. Experimental measurements of backscatter coefficient were performed on 43 human calcaneus samples in vitro. Mean trabecular thicknesses on the 43 samples were assessed using micro computed tomography (CT). A power law fit to the data showed that the backscatter coefficient empirically varied as trabecular thickness to the 2.8 power. The 95% confidence interval for this exponent was 1.7 to 3.9. The square of the correlation coefficient for the linear regression to the log transformed data was 0.40. This suggests that 40% of variations in backscatter may be attributed to variations in trabecular thickness. These results reinforce previous studies that offered validation for the Faran cylinder model for prediction of scattering properties of cancellous bone, and provide added evidence for the potential diagnostic utility of the backscatter measurement. PMID:12952089

  8. First Experimental Results with a New Type of Stent: The Double-Coil Device

    SciTech Connect

    Strecker, Ernst-Peter Song, Ho-Young; Kang, Sung-Gwon; Hou Dongming; Schumacher, M.

    2003-06-15

    Purpose: To introduce a new stent design and evaluate its technical properties. Methods: This stent consists of two nitinol wires partially connected to each other.After delivery through a catheter a tube-like helical stent forms within the artery. After experimental tests in flow models regarding mechanical properties, introduction and delivery technique, 15 stents were implanted into iliac, femoral, and carotid arteries of seven dogs.After 3-12 weeks angiographic follow-up stents were explanted for microscopic examination. Results: Stents with expanded diameters of 5-10 mm can be introduced through a 5 Fr catheter with 0.038 inch luminal diameter. Thrombotic vessel occlusion was observed in one iliac artery after incorrect stent placement with diameter mismatch. Fourteen of 15 stents remained patent and revealed minor intimal hyperplasia in the areas of the stent strut connection points as well as some reduction in medial thickness. Conclusion: This new stent design has a small introduction diameter which is independent of the expanded diameter. The stent's principal characteristics may serve as a basis for further special developments.

  9. Two-dimensional discrete element models of debris avalanches: Parameterization and the reproducibility of experimental results

    NASA Astrophysics Data System (ADS)

    Banton, J.; Villard, P.; Jongmans, D.; Scavia, C.

    2009-11-01

    Application of the discrete element method (DEM) to model avalanches of granular materials requires determining the correct geometric and rheological parameters for and between the particles as well as for the basal surface. The use of spherical (circular in 2-D) particles enhances particle rolling, yielding excessive runout values. The solution usually adopted to correct this effect is to introduce a drag force which artificially slows down the particle velocities. The aim of this study is to test the capability of the DEM to simulate well-controlled unsteady channelized granular flows, considering the measured properties of the particles and of the basal surface which naturally contribute to dissipate energy. We first performed a parametrical analysis on a simple 2-D model in order to estimate the influence of particle shape, friction parameters, and restitution coefficients on the dynamics of the flow and on the deposit geometry. We then simulated three channelized laboratory experiments performed with two materials and two bed linings. Using the geometrical layout and the values of the mechanical parameters provided by the authors, we obtained a remarkable agreement between the observed and 2-D simulated deposit shapes for the three experiments. Also, the computed mass evolution with time was very consistent with the experimental snapshots in all cases. These results highlight the capability of the DEM technique for modeling avalanche of granular material when the particle shape as well as the friction and restitution coefficients are properly considered.

  10. Inhibiting diffusion of complex contagions in social networks: theoretical and experimental results

    PubMed Central

    Anil Kumar, V.S.; Marathe, Madhav V.; Ravi, S.S.; Rosenkrantz, Daniel J.

    2014-01-01

    We consider the problem of inhibiting undesirable contagions (e.g. rumors, spread of mob behavior) in social networks. Much of the work in this context has been carried out under the 1-threshold model, where diffusion occurs when a node has just one neighbor with the contagion. We study the problem of inhibiting more complex contagions in social networks where nodes may have thresholds larger than 1. The goal is to minimize the propagation of the contagion by removing a small number of nodes (called critical nodes) from the network. We study several versions of this problem and prove that, in general, they cannot even be efficiently approximated to within any factor ρ ≥ 1, unless P = NP. We develop efficient and practical heuristics for these problems and carry out an experimental study of their performance on three well known social networks, namely epinions, wikipedia and slashdot. Our results show that these heuristics perform significantly better than five other known methods. We also establish an efficiently computable upper bound on the number of nodes to which a contagion can spread and evaluate this bound on many real and synthetic networks. PMID:25750583

  11. Experimental results on the thermal contact resistance of G-10CR composites at cryogenic temperatures

    SciTech Connect

    Phelan, P.E.; Mei, S.

    1999-07-01

    The composite material G-10CR, an epoxy resin laminate reinforced with glass filaments, is widely used in cryogenic structures, especially where thermal insulation is required. The thermal contact resistance, or its inverse, the thermal contact conductance, at a G-10CR/G-10CR interface has not previously been investigated at cryogenic temperatures. Consequently, an experimental apparatus was designed and constructed to permit measurements of the thermal contact conductance over a temperature range from 10 to 300 K, while enabling a controlled contact pressure to be applied. Such measurements for these composite materials indicated that the fiber orientation, plays a crucial role in determining the thermal contact conductance, which is greatest in the warp direction, where the glass fibers offer a high-thermal-conductance path for heat flow in parallel to the epoxy matrix. Typical results demonstrating the effect of fiber orientation on thermal contact conductance are displayed. The dimensionless contact conductance was shown to vary with dimensionless contact pressure with a power-law exponent near 0.28, in broad agreement with other data reported for graphite fiber composites.

  12. Male physical aggression as a function of alcohol intoxication and frustration: experimental results and methodological considerations.

    PubMed

    Gustafson, R

    1991-03-01

    Forty-five undergraduate students were assigned to either an Alcohol, a Placebo, or a Control group. The alcohol dose was 0.80 g of 100% alcohol/kg body weight. Subjects were informed that they could win a sum of money depending on the performance of a partner. They then supervised the partner over a series of trials on a visual scan test and could influence the partner by either giving an uncomfortable electric shock (aggressive alternative) or a comfortable vibration (nonaggressive alternative) at each incorrect response from the partner. Both alternatives were said to be equally instrumental in reaching the goal of winning the money and both could be varied in intensity on a 10-point scale and without limits in terms of duration. Aggression was measured as number of aggressive responses chosen, and in terms of intensity and duration. Nonaggression was measured in terms of intensity and duration. Intoxicated subjects did not increase their aggression but all groups chose significantly more nonaggressive responses and did so with higher intensity and duration. Frustration did not significantly affect these types of responding. Results are discussed in terms of methodological considerations and the importance of using realistic experimental paradigms is stressed. Also, theoretical implications are discussed. PMID:2058788

  13. Experimental Results From a 2kW Brayton Power Conversion Unit

    NASA Technical Reports Server (NTRS)

    Hervol, David; Mason, Lee; Birchenough, Arthur

    2003-01-01

    This paper presents experimental test results from operation of a 2 kWe Brayton power conversion unit. The Brayton converter was developed for a solar dynamic power system flight experiment planned for the Mir Space Station in 1997. The flight experiment was cancelled, but the converter was tested at Glenn Research Center as part of the Solar Dynamic Ground Test Demonstration system which included a solar concentrator, heat receiver, and space radiator. In preparation for the current testing, the heat receiver was removed and replaced with an electrical resistance heater, simulating the thermal input of a steady-state nuclear source. The converter was operated over a full range of thermal input power levels and rotor speeds to generate an overall performance map. The converter unit will serve as the centerpiece of a Nuclear Electric Propulsion Testbed at Glenn. Future potential uses for the Testbed include high voltage electrical controller development, integrated electric thruster testing and advanced radiator demonstration testing to help guide high power Brayton technology development for Nuclear Electric Propulsion (NEP).

  14. Joint computational/experimental aerodynamics research on a reentry vehicle: Part 2, Computational results

    SciTech Connect

    Walker, M.M.; Oberkampf, W.L.

    1990-01-01

    Computational aerodynamics simulation applied to supersonic and hypersonic flight vehicles has significantly increased during the last several years. Flow field simulations have been computed for a wide variety of vehicles from ballistic reentry vehicles to the Space Shuttle. Although computational aerodynamics simulation has been taking more responsibility during this time, wind tunnel experimentation has continued to play the major role in flight vehicle analysis and design. This role, however, is changing because of the great strides in the capability and confidence in numerical simulations. In this paper computational results are obtained for a spherically blunted cone with a slice parallel to the cone axis. Aerodynamic force and moment predictions from Sandia's CFD codes are compared with wind tunnel data from the Sandia Mach 8 hypersonic wind tunnel. These comparisons are made on a sliced reentry vehicle both with and without a windward flap. The windward flap will be deflected 10{degree}, 20{degree}, and 30{degree}. Inviscid/boundary layer codes and the Parabolized Navier-Stokes code are used to generate solutions for the sliced vehicle. In the region of the flap, some reversed flow is apparent and a full Navier-Stokes code will be used to provide comparisons with the data. Force and moment and surface flow visualization comparisons are made for laminar, ideal gas flow. This will be the first of a series of papers providing comparisons with the Sandia wind tunnel data. Additional papers will report comparisons with surface pressure measurements. 21 refs., 9 figs., 1 tab.

  15. Optimal piezoelectric beam shape for single and broadband vibration energy harvesting: Modeling, simulation and experimental results

    NASA Astrophysics Data System (ADS)

    Muthalif, Asan G. A.; Nordin, N. H. Diyana

    2015-03-01

    Harvesting energy from the surroundings has become a new trend in saving our environment. Among the established ones are solar panels, wind turbines and hydroelectric generators which have successfully grown in meeting the world's energy demand. However, for low powered electronic devices; especially when being placed in a remote area, micro scale energy harvesting is preferable. One of the popular methods is via vibration energy scavenging which converts mechanical energy (from vibration) to electrical energy by the effect of coupling between mechanical variables and electric or magnetic fields. As the voltage generated greatly depends on the geometry and size of the piezoelectric material, there is a need to define an optimum shape and configuration of the piezoelectric energy scavenger. In this research, mathematical derivations for unimorph piezoelectric energy harvester are presented. Simulation is done using MATLAB and COMSOL Multiphysics software to study the effect of varying the length and shape of the beam to the generated voltage. Experimental results comparing triangular and rectangular shaped piezoelectric beam are also presented.

  16. Experimental Results From Stitched Composite Multi-Bay Fuselage Panels Tested Under Uni-Axial Compression

    NASA Technical Reports Server (NTRS)

    Baker, Donald J.

    2004-01-01

    The experimental results from two stitched VARTM composite panels tested under uni-axial compression loading are presented. The curved panels are divided by frames and stringers into five or six bays with a column of three bays along the compressive loading direction. The frames are supported at the ends to resist out-of-plane translation. Back-to-back strain gages are used to record the strain and displacement transducers were used to record the out-of-plane displacements. In addition a full-field measurement technique that utilizes a camera-based-stero-vision system was used to record displacements. The panels were loaded in increments to determine the first bay to buckle. Loading was discontinued at limit load and the panels were removed from the test machine for impact testing. After impacting at 20 ft-lbs to 25 ft-lbs of energy with a spherical indenter, the panels were loaded in compression until failure. Impact testing reduced the axial stiffness 4 percent and less than 1 percent. Postbuckled axial panel stiffness was 52 percent and 70 percent of the pre-buckled stiffness.

  17. Optimization of MCAO performances: experimental results on ONERA laboratory MCAO bench

    NASA Astrophysics Data System (ADS)

    Costille, Anne; Petit, Cyril; Conan, Jean-Marc; Fusco, Thierry; Kulcsár, Caroline; Raynaud, Henri-François

    2008-07-01

    Classic Adaptive Optics (AO) is now a proven technique to correct turbulence on earth based astronomical telescopes. The corrected field of view is however limited by the anisoplanatism effect. Multi-Conjugate AO (MCAO) aims at providing a wide field of view correction through the use of several deformable mirrors and of multi-guide-star wavefront sensing. However the performance optimization of such complex systems raises new questions in terms of calibration and control. We present our current developments on performance optimization of MCAO systems. We show that performance can be significantly improved with tomographic control based on Linear Quadratic Gaussian control, compared with more standard methods. An experimental demonstration of this new approach is going to be implemented on HOMER, the recent bench developed at ONERA devoted to MCAO laboratory research. We present here results in closed-loop in AO, GLAO and MCAO with an integrator control. This bench implements two deformable mirrors and a wide field Shack-Hartman wavefront sensor.

  18. Experimental Results of High Pressure and High Strain Rate Tantalum Flow Stress on Omega and NIF

    NASA Astrophysics Data System (ADS)

    Park, Hye-Sook; Arsenlis, A.; Barton, N.; Benedetti, L.; Huntington, C.; McNaney, J.; Orlikowski, D.; Prisbrey, S.; Remington, B.; Rudd, R.; Swift, D.; Weber, S.; Wehrenberg, C.; Comley, A.

    2015-11-01

    Understanding the high pressure, high strain rate plastic deformation dynamics of materials is an area of research of high interest to planetary formation dynamics, meteor impact dynamics, and inertial confinement fusion designs. Developing predictive theoretical and computational descriptions of such systems, however, has been a difficult undertaking. We have performed many experiments on Omega, LCLS and NIF to test Ta strength models at high pressures (~ up to 4 Mbar), high strain rates (~ 107 s-1) and high strains (>30%) under ramped compression conditions using Rayleigh-Taylor and Richtmyer-Meshkov instability properties. These experiments use plasma drive to ramp compress the sample to higher pressure without shock-melting. We also studied lattice level strength mechanisms under shocked compression using a diffraction-based technique. Our studies show that the strength mechanisms from macro to micro scales are different from the traditional strength model predictions and that they are loading path dependent. We will report the experimental results. Work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under contract DE-AC52-07NA273.

  19. Preparation, conduct, and experimental results of the AVR loss-of-coolant accident simulation test

    SciTech Connect

    Kruger, K.; Bergerfurth, A.; Burger, S.; Pohl, P.; Wimmers, M. ); Cleveland, J.C. )

    1991-02-01

    A loss-of-coolant accident (LOCA) is one of the most severe accidents for a nuclear power plant. To demonstrate inherent safety characteristics incorporated into small high-temperature gas-cooled reactor (HTGR) design, LOCA simulation tests have been conducted at the Arbeitsgemeinschaft Versuchsreaktor (AVR), the German pebble-bed-high-temperature reactor plant. The AVR is the only nuclear power plant ever to have been intentionally subjected to LOCA conditions without emergency cooling. This paper presents the planning and licensing activities including pretest predictions performed for the LOCA test are described, and the conduct of the test and experimental results. The LOCA test was planned to create conditions that would exist if a rapid LOCA occurred with the reactor operating at full power. The test demonstrated this reactor's safe response to an accident in which the coolant escapes from the reactor core and no emergency system is available to provide coolant flow to the core. The test is of special interest because it demonstrates the inherent safety features incorporated into optimized modular HTGR designs. The main LOCA test lasted for 5 days. After the test began, core temperatures increased for {approx}13 h and then gradually and continually decreased as the rate of heat dissipation from the core exceeded the simulated decay power. Throughout the test, temperatures remained below limiting values for the core and other reactor components.

  20. Vibrational reduction in integral-damped composite fan blades: experimental results

    NASA Astrophysics Data System (ADS)

    Kosmatka, John B.; Mehmed, Oral

    1998-06-01

    The experimental behavior of spinning laminated composite pretwisted plates (turbo-fan blade-like) with small (less than 10% by volume) integral viscoelastic damping patches is investigated. Two different plate sets were examined. The first set investigated tailoring patch locations and definitions to damp specific modes on spinning flat graphite/epoxy plates as a function of rotational speed. The second set investigated damping patch size and location on specific modes of pretwisted (30 degrees) graphite/epoxy plates. The results reveal that: (1) significant amount of damping can be added using a small amount of damping material, (2) the damped plates experienced no failures up to the tested 28,000 g's and 750,000 cycles, (3) centrifugal loads caused an increase in bending frequencies and corresponding reductions in bending damping levels that are proportional to the bending stiffness increase, and (4) the centrifugal loads caused a decrease in torsion natural frequency and increase in damping levels of pretwisted composite plates.

  1. Experimental results performed in the framework of the HIPER European Project

    NASA Astrophysics Data System (ADS)

    Batani, D.; Koenig, M.; Baton, S.; Perez, F.; Gizzi, L. A.; Koester, P.; Labate, L.; Honrubia, J.; Debayle, A.; Santos, J.; Schurtz, G.; Hulin, S.; Ribeyre, X.; Fourment, C.; Nicolai, P.; Vauzour, B.; Gremillet, L.; Nazarov, W.; Pasley, J.; Tallents, G.; Richetta, M.; Lancaster, K.; Spindloe, Ch.; Tolley, M.; Neely, D.; Norreys, P.; Kozlova, M.; Nejdl, J.; Rus, B.; Antonelli, L.; Morace, A.; Volpe, L.,; Davies, J.; Wolowski, J.; Badziak, J.

    2011-06-01

    This paper presents the goals and some of the results of experiments conducted within the Working Package 10 (Fusion Experimental Programme) of the HiPER Project. These experiments concern the study of the physics connected to "Advanced Ignition Schemes", i.e. the Fast Ignition and the Shock Ignition Approaches to Inertial Fusion. Such schemes are aimed at achieving a higher gain, as compared to the classical approach which is used in NIF, as required for future reactors, and making fusion possible with smaller facilities. In particular, a series of experiments related to Fast Ignition were performed at the RAL (UK) and LULI, France) Laboratories and were addressed to study the propagation of fast electrons (created by a short-pulse ultra-high-intensity beam) in compressed matter, created either by cylindrical implosions or by compression of planar targets by (planar) laser-driven shock waves. A more recent experiment was performed at PALS and investigated the laser-plasma coupling in the 1016 W/cm2 intensity regime of interest for Shock Ignition.

  2. Non-Shock Initiation Model for Plastic Bonded Explosive PBXN-5 and Cast Explosive: Experimental Results

    NASA Astrophysics Data System (ADS)

    Anderson, Mark; Todd, Steven; Caipen, Terry; Jensen, Charlie; Hughs, Chance

    2009-06-01

    A damage initiated reaction (DMGIR) computational model is being developed for the CTH shock physics code to predict the response of an explosive to non-shock mechanical insults. The distinguishing feature of this model is the introduction of a damage variable, which relates the evolution of damage to the initiation of reaction in the explosive, and its growth to detonation. The DMGIR model is a complement to the History Variable Reactive Burn (HVRB) model embedded in the current CTH code. Specifically designed experiments are supporting the development, implementation, and validation of the DMGIR numerical approach. PBXN-5 was the initial explosive material used experimentally to develop the DMGIR model. This explosive represents a family of plastically bonded explosives with good mechanical strength and rigid body properties. The model has been extended to cast explosives represented by Composition B. Furthermore, the DMGIR model will extended to predict results of non-shock mechanical insults for moldable plastic explosives such as C4 and PrimaSheet.

  3. First Experimental Results Using Sparse Aperture Mask for Low Order Wavefront Sensing

    NASA Astrophysics Data System (ADS)

    Subedi, Hari; Zimmerman, Neil T.; Kasdin, N. Jeremy; Eldorado Riggs, A. J.

    2016-01-01

    We can determine the existence of life outside of earth by analyzing the spectra of exoplanets. Such direct imaging will provide the capability to thoroughly characterize an exoplanet's atmosphere. Direct imaging of exoplanets, however, has many technical challenges and difficulties: scattering and diffraction of light and the large difference in contrast, which is the ratio of brightness between the bright star and the dimmer planet. A coronagraph is an optical device that manipulates the diffraction of starlight and creates a region of high contrast (dark hole) where the dimmer planets can be seen. While in principle the level of contrast required for direct imaging of exoplanets can be achieved by stellar coronagraphic imaging, the resulting dark hole is highly sensitive to phase aberrations. In order to effectively suppress starlight for exoplanet imaging applications, low-order wavefront aberrations entering a coronagraph such as tip-tilt, defocus and coma must be determined and compensated for. A sparse-aperture mask (SAM) can be integrated in the telescopic imaging system to make precise estimate of low-order wavefront aberrations. In this technique, the starlight rejected by the coronagraph's focal plane stop is collimated to a relay pupil, where the mask forms an interference fringe pattern on a detector and the phase aberrations are inferred from this fringe pattern. At Princeton's High Contrast Imaging Lab (HCIL), we have numerically proved this concept and we are currently working on verifying it experimentally.

  4. A 2D optomechanical focused laser spot scanner: analysis and experimental results for microstereolithography

    NASA Astrophysics Data System (ADS)

    Gandhi, P. S.; Deshmukh, S.

    2010-01-01

    This paper proposes and analyzes a 2D optomechanical-focused laser spot scanning system (patent pending) which allows uniform intensity focused spot scanning with high speed and high resolution over a large range of scan. Such scanning is useful where variation of focused spot characteristics affects the performance of applications such as micro-/nano-stereolithography, laser micro-machining, scanning optical tweezers, optical scanning microscopy, and so on. Proposed scanning is achieved by using linear movement of mirrors and lens maintaining the alignment of motion and optical axis of laser. Higher speed and high resolution at the same time are achieved by use of two serial double parallelogram flexural mechanisms with mechatronics developed around them. Optical analysis is carried out to demonstrate effectiveness of the proposed system numerically and is further supported by the experimental results. Additional analysis is carried out to demonstrate robustness of the scanner in the case of small misalignment errors incurred in actual practice. Although the proposed scanner is useful in general in several applications mentioned above, discussion in this paper is focused on microstereolithography.

  5. Experimental results using a nonlinear extension of the minimum average correlation energy (MACE) filter

    NASA Astrophysics Data System (ADS)

    Fisher, John W., III; Principe, Jose C.

    1995-03-01

    The minimum average correlation energy filter (MACE) filter has been shown to have superior performance for rejecting out of class inputs in pattern recognition applications. The MACE filter exhibits a sharp correlation peak at a specified location in the output plane and low correlation energy elsewhere. It has also been shown that the MACE filter suffers from poor generalization. Increasing the number of exemplars used to compute the filter coefficients can improve the generalization, but the number of exemplars is restricted by the stability of the computation. We show a simple extension of the MACE filter to nonlinear processing techniques (i.e. nonlinear associative memories) which exhibits improved generalization and discrimination performance. The operating parameters of the proposed extension are difficult to compute analytically and adaptive learning methods are needed. Since the output of the MACE filter is optimized over the output plane any nonlinear extension of the MACE filter should encompass the output plane as well. In general this leads to exhaustive training over the entire output plane over all training exemplars. We present an efficient method for computing the parameters of the nonlinear extension which greatly reduces the training iterations required. Experimental results with 35 GHz inverse synthetic aperture radar (ISAR) data are also shown.

  6. MHD activity in the ISX-B tokamak: experimental results and theoretical interpretation

    SciTech Connect

    Carreras, B.A.; Dunlap, J.L.; Bell, J.D.; Charlton, L.A.; Cooper, W.A.; Dory, R.A.; Hender, T.C.; Hicks, H.R.; Holmes, J.A.; Lynch, V.E.

    1982-01-01

    The observed spectrum of MHD fluctuations in the ISX-B tokamak is clearly dominated by the n=1 mode when the q=1 surface is in the plasma. This fact agrees well with theoretical predictions based on 3-D resistive MHD calculations. They show that the (m=1; n=1) mode is then the dominant instability. It drives other n=1 modes through toroidal coupling and n>1 modes through nonlinear couplings. These theoretically predicted mode structures have been compared in detail with the experimentally measured wave forms (using arrays of soft x-ray detectors). The agreement is excellent. More detailed comparisons between theory and experiment have required careful reconstructions of the ISX-B equilibria. The equilibria so constructed have permitted a precise evaluation of the ideal MHD stability properties of ISX-B. The present results indicate that the high ..beta.. ISX-B equilibria are marginally stable to finite eta ideal MHD modes. The resistive MHD calculations also show that at finite ..beta.. there are unstable resistive pressure driven modes.

  7. Development, calibration, and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    SciTech Connect

    Carcreff, Hubert; Cloute-Cazalaa, Veronique; Salmon, Laurent

    2012-08-15

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Division at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  8. Development, calibration and experimental results obtained with an innovative calorimeter (CALMOS) for nuclear heating measurements

    SciTech Connect

    Carcreff, H.; Cloute-Cazalaa, V.; Salmon, L.

    2011-07-01

    Nuclear heating inside an MTR reactor has to be known in order to be able to control samples temperature during irradiation experiments. An R and D program has been carried out at CEA to design a new type of in-core calorimetric system. This new development, started in 2002, has for main objective to manufacture a calorimeter suitable to monitoring nuclear heating inside the 70 MWth OSIRIS material testing reactor operated by CEA's Nuclear Energy Div. at the Saclay research center. An innovative calorimetric probe, associated to a specific handling system, has been designed to provide access to measurements both along the fissile height and on the upper part of the core, where nuclear heating still remains high. Two mock-ups of the probe were manufactured and tested in 2005 and 2009 in ex-core area of OSIRIS reactor for process validation, while a displacement system has been especially studied to move the probe along a given axial measurement range. This paper deals with the development, tests on preliminary mock-ups and the finalization of the probe. Main modeling and experimental results are presented. Moreover, alternative methods to calibration for nuclear heating rate measurements which are now possible with this new calorimeter are presented and discussed. (authors)

  9. Wageningen Urban Rainfall Experiment 2014 (WURex14): Experimental Setup and First Results

    NASA Astrophysics Data System (ADS)

    van Leth, Thomas; Uijlenhoet, Remko; Overeem, Aart; Leijnse, Hidde; Hazenberg, Pieter

    2015-04-01

    the atmosphere. Approximately halfway along the link path a rain gauge from the KNMI operational network is located. Finally, data is available from several commercial microwave links in the vicinity of the experimental setup, as well as from the KNMI weather radars. We report on the first results from this experiment, collected during the Summer and Fall of 2014.

  10. CZT detectors used in different irradiation geometries: Simulations and experimental results

    SciTech Connect

    Fritz, Shannon G.; Shikhaliev, Polad M.

    2009-04-15

    The purpose of this work was to evaluate potential advantages and limitations of CZT detectors used in surface-on, edge-on, and tilted angle irradiation geometries. Simulations and experimental investigations of the energy spectrum measured by a CZT detector have been performed using different irradiation geometries of the CZT. Experiments were performed using a CZT detector with 10x10 mm{sup 2} size and 3 mm thickness. The detector was irradiated with collimated photon beams from Am-241 (59.5 keV) and Co-57 (122 keV). The edge-scan method was used to measure the detector response function in edge-on illumination mode. The tilted angle mode was investigated with the radiation beam directed to the detector surface at angles of 90 degree sign , 15 degree sign , and 10 degree sign . The Hecht formalism was used to simulate theoretical energy spectra. The parameters used for simulations were matched to experiment to compare experimental and theoretical results. The tilted angle CZT detector suppressed the tailing of the spectrum and provided an increase in peak-to-total ratio from 38% at 90 degree sign to 83% at 10 degree sign tilt angle for 122 keV radiation. The corresponding increase for 59 keV radiation was from 60% at 90 degree sign to 85% at 10 degree sign tilt angle. The edge-on CZT detector provided high energy resolution when the beam thickness was much smaller than the thickness of CZT. The FWHM resolution in edge-on illumination mode was 4.2% for 122 keV beam with 0.3 mm thickness, and rapidly deteriorated when the thickness of the beam was increased. The energy resolution of surface-on geometry suffered from strong tailing effect at photon energies higher than 60 keV. It is concluded that tilted angle CZT provides high energy resolution but it is limited to a 1D linear array configuration. The surface-on CZT provides 2D pixel arrays but suffers from tailing effect and charge build up. The edge-on CZT is considered suboptimal as it requires small beam

  11. Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results

    NASA Astrophysics Data System (ADS)

    Radhakrishnan, Sreeram

    Underwater intrusion detection is an ongoing security concern in port and harbor areas. Of particular interest is to detect SCUBA divers, unmanned underwater vehicles and small boats from their acoustic signature. A thorough understanding of the effects of the shallow water propagating medium on acoustic signals can help develop new technologies and improve the performance of existing acoustic based surveillance systems. The Hudson River Estuary provides us with such a shallow water medium to conduct research and improve our knowledge of shallow water acoustics. Acoustic propagation in the Hudson River Estuary is highly affected by the temporal and spatial variability of salinity and temperature due to tides, freshwater inflows, winds etc. The primary goal of this research is to help develop methodologies to predict the formation of an acoustic field in the realistic environment of the lower Hudson River Estuary. Shallow water high-frequency acoustic propagation experiments were conducted in the Hudson River near Hoboken, New Jersey. Channel Impulse Response (CIR) measurements were carried out in the frequency band from 10 to 100 kHz for distances up to 200 meters in a water depth of 8-10 meters which formed the basis for experimental Transmission Loss (TL). CIR data was also utilized to demonstrate multi-path propagation in shallow water. Acoustic propagation models based on Ray Theory and Parabolic Equation methods were implemented in the frequency band from 10 to 100 kHz and TL was estimated. The sound velocity profiles required as input by acoustic propagation models were calculated from in-situ measurements of temperature, salinity and depth. Surface reflection loss was obtained from CIR data and incorporated into the acoustic propagation models. Experimentally obtained TL was used to validate the acoustic model predictions. An outcome of this research is an operational acoustic transmission loss (TL) forecast system based on the existing, Stevens New York

  12. Wageningen Urban Rainfall Experiment 2014 (WURex14): Experimental Setup and First Results

    NASA Astrophysics Data System (ADS)

    Uijlenhoet, R.; Overeem, A.; Leijnse, H.; Hazenberg, P.

    2014-12-01

    the atmosphere. Approximately halfway along the link path a rain gauge from the KNMI operational network is located. Finally, data is available from several commercial microwave links in the vicinity of the experimental setup, as well as from the KNMI weather radars. We report on the first results from this experiment, collected during the Summer and Fall of 2014.

  13. A comparison of experimental and theoretical results for rotordynamic coefficients of four annular gas seals

    NASA Technical Reports Server (NTRS)

    Childs, D. W.; Nelson, C. C.; Elrod, D.; Nicks, C.

    1985-01-01

    The test facility and initial test program developed to experimentally measure the fluid forces induced by annular gas seals is described. A comparison of theoretically predicted and experimentally obtained data for smooth and honeycomb seals is provided. And a comparison of experimental data from the tests of three smooth-rotor/smooth-stator seals is provided. The leakage of the working fluid through the seal, the pressure gradient along the seal length, entrance pressure-loss data, and rotordynamic coefficients provide a basis for comparison. A short discussion on seal theory is included, and various rotordynamic coefficient identification schemes are described.

  14. NASA/Pratt and Whitney experimental clean combustor program: Engine test results

    NASA Technical Reports Server (NTRS)

    Roberts, R.; Fiorentino, A. J.; Greene, W.

    1977-01-01

    A two-stage vorbix (vortex burning and mixing) combustor and associated fuel system components were successfully tested in an experimental JT9D engine at steady-state and transient operating conditions, using ASTM Jet-A fuel. Full-scale JT9D experimental engine tests were conducted in a phase three aircraft experimental clean combustor program. The low-pollution combustor, fuel system, and fuel control concepts were derived from phase one and phase two programs in which several combustor concepts were evaluated, refined, and optimized in a component test rig. Significant pollution reductions were achieved with the combustor which meets the performance, operating, and installation requirements of the engine.

  15. Nitrogen-broadened lineshapes in the oxygen A-band: Experimental results and theoretical calculations

    NASA Astrophysics Data System (ADS)

    Predoi-Cross, Adriana; Holladay, Christopher; Heung, Henry; Bouanich, Jean-Pierre; Mellau, Georg Ch.; Keller, Reimund; Hurtmans, Daniel R.

    2008-09-01

    We report measurements for N 2-broadening, pressure-shift and line mixing coefficients for 55 oxygen transitions in the A-band retrieved using a multispectrum fitting technique. Nineteen laboratory absorption spectra were recorded at 0.02 cm -1 resolution using a multi-pass absorption cell with path length of 1636.9 cm and the IFS 120 Fourier transform spectrometer located at Justus-Liebig-University in Giessen, Germany. The total sample pressures ranged from 8.8 to 3004.5 Torr with oxygen volume mixing ratios in nitrogen ranging between 0.057 and 0.62. An Exponential Power Gap (EPG) scaling law was used to calculate the N 2-broadening and N 2-line mixing coefficients. The line broadening and shift coefficients for the A-band of oxygen self-perturbed and perturbed by N 2 are modeled using semiclassical calculations based on the Robert-Bonamy formalism and two intermolecular potentials. These potentials involve electrostatic contributions including the hexadecapole moment of the molecules and (a) a simple dispersion contribution with one adjustable parameter to fit the broadening coefficients or (b) the atom-atom Lennard-Jones model without such adjustable parameters. The first potential leads to very weak broadening coefficients for high J transitions whereas the second potential gives much more improved results at medium and large J values, in reasonable agreement with the experimental data. For the line shifts which mainly arise in our calculation from the electronic state dependence of the isotropic potential, their general trends with increasing J values can be well predicted, especially from the first potential. From the theoretical results, we have derived air-broadening and air-induced shift coefficients with an agreement comparable to that obtained for O 2-O 2 and O 2-N 2.

  16. Initial Experimental Results of a Laboratory Mini-Magnetosphere for Astronaut Protection

    NASA Astrophysics Data System (ADS)

    Bamford, R. A.; Bingham, R.; Gibson, K.; Thornton, A.; Bradford, J.; Hapgood, M.; Gargate, L.; Silva, L.; Norberg, C.; Todd, T.; Wilson, H.; Stamper, R.

    2007-12-01

    Radiation is a major scientific and technological challenge for manned missions to Mars. With an interplanetary flight time of months to years there is a high probability of Solar Energetic Particle events during the flight. Radiation damage to human tissue could result in acute sickness or death of the occupants of an unprotected spacecraft. Thus there is much interest in techniques to mitigate the effects of these events and of the exposure to cosmic rays. The experimental and modelling work presented here concerns one of several innovative "Active Shield" solutions being proposed [1]. The idea of generating an artificial magnetosphere to recreate the protective shield of the Earth's magnetic field for space craft travelling to the Moon or Mars was considered seriously in the 1960's during the Apollo era. With most of the space agencies around the world setting their sights returning to the Moon and then on to Mars, the idea of some sort of active field solution is experiencing a resurgence. Results from the laboratory experiment to determine the effectiveness of a mini-magnetosphere barrier to be able to expel a flowing energetic "solar wind" plasma will be presented. This is compared to a 3D hybrid simulation code that has been successfully compared to other astrophysical situations e.g. AMPTE artificial comet releases [2]. The experiment and modelling comparisons will demonstrate the scalability between the laboratory and astrophysical scale. [1] Adams, J.H. et al., "Revolutionary Concepts of Radiation Shielding for Human Exploration of Space", NASA/TM- 2005-213688, March 2005. [2] Gargate, L.; Bingham, R.; Fonseca, R. A.; Silva, L. O., "dHybrid: A massively parallel code for hybrid simulations of space plasmas", Computer Physics Communications, Volume 176, Issue 6, Pages 419-425, 15 March 2007, doi:10.1016/j.cpc.2006.11.013

  17. Experimental investigations of the use of an erbium:YAG laser on temporomandibular joint (TMJ) structures: first experimental results

    NASA Astrophysics Data System (ADS)

    Nuebler-Moritz, Michael; Niederdellmann, Herbert; Hering, Peter; Deuerling, Christian; Dammer, Ralf; Behr, M.

    1995-04-01

    The following paper introduces the results of an interdisciplinary research project. With the aid of photomacroscopic examination, light and scanning electron microscope investigations, changes to temporomandibular joint structures were detected in vitro after irradiation with an Erbium:YAG laser system. The solid-state Erbium:YAG laser, operating at a wavelength of 2.94 micrometers was used in the normal- spiking mode. The free-running laser beam was focussed onto freshly excised porcine tissue samples using a 108-mm sapphire lens. In this study the output was generally pulsed at a repetition rate of 4 Hz, with a pulse duration varying from 120 microsecond(s) to 500 microsecond(s) . Between 50 mJ and 500 mJ per pulse were applied to create pinpoint lesions. The optimum average energy density and pulse duration of the Erbium:YAG laser radiation for the purpose of TMJ-surgery (as far as it concerns meniscus and articulating facets) - which means efficient etch rate and minimal adjacent injury - seems to be about 24-42 J/cm2 and 120 microsecond(s) -240 microsecond(s) , respectively.

  18. Review on optical constants of Titan aerosols: Experimental results and modeling/observational data

    NASA Astrophysics Data System (ADS)

    Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

    2014-05-01

    During the last years many studies have been performed to improve the experimental database of optical constants of Titan aerosols. Indeed, the determination of the optical constants of these particles is essential to quantify their capacity to absorb and to scatter solar radiation, and thus to evaluate their role on Titan's radiative balance and climate. The study of optical properties is also crucial to analyze and to better interpret many of Titan's observational data, in particular those acquired during the Cassini-Huygens mission. One way to determine Titan aerosols optical constant is to measure the optical constants of analogues of Titan complex organic material synthesized in the laboratory, usually named Titan's tholins (Sagan and Khare, 1979). But the optical constants depend on the chemical composition, the size and the shape of particles (Raulin et al., 2012). Those three parameters result from the experimental conditions such as energy source, gas mixing ratio, gas pressure, flow rate and irradiation time (Cable et al., 2012). Besides the determination of the refractive index in the laboratory, there are others methods using theoretical models or observational data. Nevertheless, theoretical models are based on laboratory data or/and observational data. The visible - near infrared spectral region of optical constants has been widely studied with laboratory analogues. Comparison of the obtained results suggest that tholins synthesized by Tran et al. (2003) and Majhoub et al. (2012) are the best representative of Titan aerosols with regards to their refractive indexes in this spectral region. The mid-infrared spectral range has been studied only by Imanaka et al. (2012) and slightly by Tran et al. (2003). In that spectral range, Titan tholins do not exhibit the features displayed by Kim and Courtin (2013) from Titan's observations. For spectral region of wavelengths smaller than 0.20µm or higher than 25µm, only the data from Khare et al. (1984) are

  19. Data processing and display of laser Doppler experimental results, volume 1

    NASA Technical Reports Server (NTRS)

    Ashmore, B. R.; Kimura, A.; Skeith, R. W.

    1976-01-01

    Contract activities performed in developing a laser Doppler system for detecting, tracking, and measuring aircraft wake vortices are summarized. The computer program for processing and displaying the Dust Devil experimental data is presented. Program listings are included in the appendix.

  20. Coherent optical receiver for PPM signals received through atmospheric turbulence: performance analysis and preliminary experimental results

    NASA Technical Reports Server (NTRS)

    Munoz Fernandez, M.; Vilnrotter, V. A.

    2004-01-01

    The performance of a coherent free-space optical communications system is investigated. Bit Error Rate (BER) performance is analyzed, and laboratory equipment and experimental setup used to carry out these experiments at JPL are described.

  1. Experimental results from containment piping bellows subjected to severe accident conditions: Results from bellows tested in corroded conditions. Volume 2

    SciTech Connect

    Lambert, L.D.; Parks, M.B.

    1995-10-01

    Bellows are an integral part of the containment pressure boundary in nuclear power plants. They are used at piping penetrations to allow relative movement between piping and the containment wall, while minimizing the load imposed on the piping and wall. Piping bellows are primarily used in steel containments; however, they have received limited use in some concrete (reinforced and prestressed) containments. In a severe accident they may be subjected to pressure and temperature conditions that exceed the design values, along with a combination of axial and lateral deflections. A test program to determine the leak-tight capacity of containment penetration bellows is being conducted at Sandia National Laboratories under the sponsorship of the US Nuclear Regulatory Commission. Several different bellows geometries, representative of actual containment bellows, have been subjected to extreme deflections along with pressure and temperature loads. The bellows geometries and loading conditions are described along with the testing apparatus and procedures. A total of nineteen bellows have been tested. Thirteen bellows were tested in ``like-new`` condition (results reported in Volume 1), and six were tested in a corroded condition. The tests showed that bellows in ``like-new`` condition are capable of withstanding relatively large deformations, up to, or near, the point of full compression or elongation, before developing leakage, while those in a corroded condition did not perform as well, depending on the amount of corrosion. The corroded bellows test program and results are presented in this report.

  2. Evaluating Impacts of CO2 Gas Intrusion Into a Confined Sandstone aquifer: Experimental Results

    DOE PAGESBeta

    Qafoku, Nikolla; Lawter, Amanda R.; Shao, Hongbo; Wang, Guohui; Brown, Christopher F.

    2014-12-31

    Deep subsurface storage and sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Experimental and modeling work is required to evaluate potential risks to groundwater quality and develop a systematic understanding of how CO2 leakage may cause important changes in aquifer chemistry and mineralogy by promoting dissolution/precipitation, adsorption/desorption, and redox reactions. Sediments from the High Plains aquifer in Kansas, United States, were used in this investigation, which is part of the National Risk Assessment Partnershipmore » Program sponsored by the US Department of Energy. This aquifer was selected to be representative of consolidated sand and gravel/sandstone aquifers overlying potential CO2 sequestration repositories within the continental US. In this paper, we present results from batch experiments conducted at room temperature and atmospheric pressure with four High Plains aquifer sediments. Batch experiments simulate sudden, fast, and short-lived releases of the CO2 gas as would occur in the case of well failure during injection. Time-dependent release of major, minor, and trace elements were determined by analyzing the contacting solutions. Characterization studies demonstrated that the High Plains aquifer sediments were abundant in quartz and feldspars, and contained about 15 to 20 wt% montmorillonite and up to 5 wt% micas. Some of the High Plains aquifer sediments contained no calcite, while others had up to about 7 wt% calcite. The strong acid extraction tests confirmed that in addition to the usual elements present in most soils, rocks, and sediments, the High Plains aquifer sediments had appreciable amounts of As, Cd, Pb, Cu, and occasionally Zn, which potentially may be mobilized from the solid to the aqueous phase during or after exposure to CO2. However

  3. Effect of Hydrodynamics on Particle Transport in Saturated Fractures: Experimental and Simulation Results

    NASA Astrophysics Data System (ADS)

    Cianflone, S.; Lakhian, V.; Dickson, S. E.

    2014-12-01

    experimental results. These results suggest that local hydrodynamics are important in defining the transport of particles through a fracture. We plan to discuss further applications, general statistics, and particle retention in fractures due to hydrodynamics and ultimately the role of fracture geometry in particle transport.

  4. Evaluating Impacts of CO2 Gas Intrusion Into a Confined Sandstone aquifer: Experimental Results

    SciTech Connect

    Qafoku, Nikolla; Lawter, Amanda R.; Shao, Hongbo; Wang, Guohui; Brown, Christopher F.

    2014-12-31

    Deep subsurface storage and sequestration of CO2 has been identified as a potential mitigation technique for rising atmospheric CO2 concentrations. Sequestered CO2 represents a potential risk to overlying aquifers if the CO2 leaks from the deep storage reservoir. Experimental and modeling work is required to evaluate potential risks to groundwater quality and develop a systematic understanding of how CO2 leakage may cause important changes in aquifer chemistry and mineralogy by promoting dissolution/precipitation, adsorption/desorption, and redox reactions. Sediments from the High Plains aquifer in Kansas, United States, were used in this investigation, which is part of the National Risk Assessment Partnership Program sponsored by the US Department of Energy. This aquifer was selected to be representative of consolidated sand and gravel/sandstone aquifers overlying potential CO2 sequestration repositories within the continental US. In this paper, we present results from batch experiments conducted at room temperature and atmospheric pressure with four High Plains aquifer sediments. Batch experiments simulate sudden, fast, and short-lived releases of the CO2 gas as would occur in the case of well failure during injection. Time-dependent release of major, minor, and trace elements were determined by analyzing the contacting solutions. Characterization studies demonstrated that the High Plains aquifer sediments were abundant in quartz and feldspars, and contained about 15 to 20 wt% montmorillonite and up to 5 wt% micas. Some of the High Plains aquifer sediments contained no calcite, while others had up to about 7 wt% calcite. The strong acid extraction tests confirmed that in addition to the usual elements present in most soils, rocks, and sediments, the High Plains aquifer sediments had appreciable amounts of As, Cd, Pb, Cu, and occasionally Zn, which potentially may be mobilized from the solid to the aqueous phase during or after exposure to CO2. However, the

  5. Hazards by shock waves during explosive eruptions: preliminary results of experimental investigations.

    NASA Astrophysics Data System (ADS)

    Scolamacchia, Teresa; Alatorre Ibarguengoïtia, Miguel; Spieler, Oliver; Dingwell, Donald B.

    2010-05-01

    velocities (205 to 257 m/s) were obtained for smaller grain-sizes, in a range of fine lapilli-medium ash (2.8 to 177 μm). Lower velocities, 40 m/s to 85 m/s, were attained by medium (8 mm) and fine lapilli (4 mm), respectively. These values seem not directly related to the the material composition. Impacts craters on steel plates were experimentally obtained, but we did not observe a modification of the steel inner structure, as observed in the original impacted pole. These results are in agreement with impacts occurred at low particle velocities, typical for gravity driven currents, as those reached in these experiments. We observed a great reduction in grain-size of samples recovered after all experiments with respect to the original material. Such evidence coud be due not only to the disruption of grains when impacting the metal plate, but also to processes stricly related to shock wave propagation and gas expansion. These preliminary results need to be further investigated.

  6. Interesting experimental results in Japan Proton Accelerator Research Complex H- ion-source development (invited).

    PubMed

    Ueno, A; Oguri, H; Ikegami, K; Namekawa, Y; Ohkoshi, K

    2010-02-01

    The following interesting experimental results observed in Japan Proton Accelerator Research Complex (J-PARC) H(-) ion-source developments are reviewed. It was proven that almost all of H(-) ions were produced with surface reactions in cesium (Cs)-free J-PARC H(-) ion-sources. The world's most intense class H(-) ion current of 38 mA in Cs-free ion sources for a high-energy linac was attained by an optimal shape and high temperature of the plasma electrode (PE), usage of a lanthanum hexaboride (LaB(6)) filament, and a newly devised high-power constant-current pulsed-arc power supply indispensable for it. It was also proven that the H(-) ion current could be increased to more than 40 mA by optimizing LaB(6)-filament shape. The surface elemental analysis of the PE after operation with a LaB(6)-filament showed that it was coated by boron (B) 95.5%, lanthanum (La) 2.5%, and oxygen (O) 1.9%. The H(-) ion current decreased by about 20% when a tungsten (W) filament was used instead of a LaB(6)-filament. The H(-) ion current could not be increased by seeding cesium (Cs) if the LaB(6)-filament was used. On the other hand, it was increased to more than 70 mA with much lower arc current of 150 A if Cs was seeded when a W-filament was used. PMID:20192389

  7. Experimental study of the tritium distribution in the effluents resulting from the sodium hydrolysis

    SciTech Connect

    Chassery, A.; Lorcet, H.; Godlewski, J; Liger, K.; Latge, C.; Joulia, X.

    2015-03-15

    Within the framework of the dismantling of fast breeder reactors in France several processes are under investigation regarding sodium disposal. One of them, called ELA (radioactive sodium waste treatment process), is based on the implementation of the sodium-water reaction, in a controlled and progressive way, to remove residual sodium. This sodium contains impurities such as sodium hydride, sodium oxide and tritiated sodium hydride. The hydrolysis of these various chemical species leads to the production of a liquid effluent, mainly composed of an aqueous solution of sodium hydroxide, and a gaseous effluent, mainly composed of nitrogen (inert gas), hydrogen and steam. The tritium is distributed between these effluents, and, within the gaseous effluent, according to its forms HT and HTO (tritiated water). HTO being 10,000 times more radio-toxic than HT, a precise knowledge of the mechanisms governing the phase distribution of tritium is necessary. This paper presents the first experimental results from a parametric study on the tritium distribution between the various effluents generated during hydrolysis operations. A series of experiments have been performed in order to study the influence of water flow rate, argon flow rate, initial mass and specific activity of the hydrolyzed sodium sample. An important influence of the total tritium concentration in the hydrolyzed sample has been highlighted. As for the phenomena suspected to be responsible for the phase change of tritiated water, in the studied range of parameters, vaporization induced by the heat of reactions seems to be dominant over the evaporation induced by the inert gas flow rate.

  8. The effect of ambient pressure on well chamber response: experimental results with empirical correction factors.

    PubMed

    Griffin, S L; DeWerd, L A; Micka, J A; Bohm, T D

    2005-03-01

    For some air-communicating well-type chambers used for low-energy brachytherapy source assay, deviations from expected values of measured air kerma strength were observed at low pressures associated with high altitudes. This effect is consistent with an overcompensation by the air density correction to standard atmospheric temperature and pressure (P(TP)). This work demonstrates that the P(TP) correction does not fully compensate for the high altitude pressure effects that are seen with air-communicating chambers at low photon energies in the range of 20-100 keV. Deviations of up to 18% at a pressure corresponding to an approximate elevation of 8500 ft for photon energies of 20 keV are possible. For high-energy photons and for high-energy beta emitters in air-communicating chambers the P(TP) factor is applicable. As expected, the ambient pressure does not significantly affect the response of pressurized well chambers (within 1%) to either low- or high-energy photons. However, when used with beta emitters, pressurized chambers appear to exhibit a slight dependence on the ambient pressure. Using measured data, the response and correction factors were determined for three models of air-communicating well chambers for low-energy photon sources at various pressures corresponding to elevations above sea level. Monte Carlo calculations were also performed which were correlated with the experimental findings. A more complete study of the Monte Carlo calculations is presented in the accompanying paper, "The effect of ambient pressure on well chamber response: Monte Carlo calculated results for the HDR1000 Plus." PMID:15839341

  9. Soil Moisture Monitoring Using GNSS-R Signals; First Experimental Results with the SAM Sensor

    NASA Astrophysics Data System (ADS)

    Egido, A.; Martin-Puig, C.; Felip, D.; Garcia, M.; Caparrini, M.; Farres, E.; Ruffini, G.

    2009-04-01

    is the most sensitive band to soil volumetric water content, i.e. soil moisture. Secondly, variations on thermal background do not contaminate GNSS-R signals as they do for other remote sensing techniques, such as radiometry. Finally, GNSS scatterometry from space has a potential higher spatial resolution than microwave radiometry, due to the highly stable carrier and code modulations of the incident signals which enables the use of Delay Doppler Mapping. However, in order to be able to obtain accurate SM estimates there are several effects that need to be taken into consideration. Some of those are mainly due to diffuse scattering effects over the soil surface, for instance effects due to surface roughness, vegetation canopy, and noise. This paper reviews the theoretical approach for SM retrieval using GNSS-R, and focuses on the description of the development of an innovative GNSS-R system for soil moisture retrieval (named SAM). The validation campaigns performed with the SAM sensor, together with the results obtained are presented in the paper, which is finalized with the conclusions achieved and the ideas for future work on GNSS-R based sensors. AKNOWLEDGEMENTS The authors would like to thank the European Space Agency for partially funding the SAM system development in the framework of the GSTP program, and Tragsatec for their collaboration in the acquisition of ground truth data and satellite imagery processing used for the SAM instrument validation. REFERENCES [1] A. Kavak, G. Xu, W.J. Vogel, GPS Multipath Fade Meassurements to Determine L-Band Ground Reflectivity Properties, University of Texas, Austin, 1998. [2] D. Masters, V. Zavorotny, S. Katzberg, W. Emery GPS Signal Scattering from Land for Moisture Content Determination IGARSS Proceedings, July 24-28, 2000.

  10. Modeling the effect of cell-associated polymeric fluid layers on force spectroscopy measurements. Part II: experimental results and comparison with model predictions.

    PubMed

    Coldren, Faith M; Foteinopoulou, Katerina; Verbeeten, Wilco M H; Carroll, David L; Laso, Manuel

    2008-09-01

    In this paper, experimentally obtained force curves on Staphylococcus aureus are compared with a previously developed model that incorporates hydrodynamic effects of extracellular polysaccharides together with the elastic response of the bacterium and cantilever. Force-displacement curves were predicted without any adjustable parameters. It is demonstrated that experimental results can be accurately described by our model, especially if viscoelastic effects of the extracellular polysaccharide layer are taken into account. Polysaccharide layer viscoelasticity was treated by means of a multimode Phan-Thien/Tanner (PTT) constitutive equation. Typical maximum relaxation times range from 0.2 to 2 s, whereas the corresponding zero-shear-rate viscosities are 6-9 Pa.s, based on published, steady-state rheological measurements on Staphylococcus aureus polysaccharide extracted from its native environment. The bacterial elastic constant is found to be in the range 0.02-0.4 N/m, corresponding to bacterial wall Young's moduli in the range of a few hundred MPa. Repeatability of measurements performed on different bacteria is found to be only fair, due to large individuum variability, whereas repetitions of measurements on the same bacterium showed high reproducibility. Improved force-indentation curve predictions are expected if transient rheological characterization of extracellular polysaccharides is available. More desirable however is the direct, in vivo rheological characterization of the extracellular polysaccharide. A model-based analysis of experimental force-indentation curves shows that appreciable further experimental improvements are still necessary to achieve this goal. PMID:18666789

  11. Modeling the Fracturing of Rock by Fluid Injection - Comparison of Numerical and Experimental Results

    NASA Astrophysics Data System (ADS)

    Heinze, Thomas; Galvan, Boris; Miller, Stephen

    2013-04-01

    Fluid-rock interactions are mechanically fundamental to many earth processes, including fault zones and hydrothermal/volcanic systems, and to future green energy solutions such as enhanced geothermal systems and carbon capture and storage (CCS). Modeling these processes is challenging because of the strong coupling between rock fracture evolution and the consequent large changes in the hydraulic properties of the system. In this talk, we present results of a numerical model that includes poro-elastic plastic rheology (with hardening, softening, and damage), and coupled to a non-linear diffusion model for fluid pressure propagation and two-phase fluid flow. Our plane strain model is based on the poro- elastic plastic behavior of porous rock and is advanced with hardening, softening and damage using the Mohr- Coulomb failure criteria. The effective stress model of Biot (1944) is used for coupling the pore pressure and the rock behavior. Frictional hardening and cohesion softening are introduced following Vermeer and de Borst (1984) with the angle of internal friction and the cohesion as functions of the principal strain rates. The scalar damage coefficient is assumed to be a linear function of the hardening parameter. Fluid injection is modeled as a two phase mixture of water and air using the Richards equation. The theoretical model is solved using finite differences on a staggered grid. The model is benchmarked with experiments on the laboratory scale in which fluid is injected from below in a critically-stressed, dry sandstone (Stanchits et al. 2011). We simulate three experiments, a) the failure a dry specimen due to biaxial compressive loading, b) the propagation a of low pressure fluid front induced from the bottom in a critically stressed specimen, and c) the failure of a critically stressed specimen due to a high pressure fluid intrusion. Comparison of model results with the fluid injection experiments shows that the model captures most of the experimental

  12. Marine pollution network euromar-mermaid: Results of the experimental operation

    NASA Astrophysics Data System (ADS)

    Knauth, H.-D.; Schroeder, F.; Menzel, R.; Gebhart, E.; Marx, S.; Kohnke, D.; Holzkamm, F.; Nies, H.; Theobald, N.

    1997-09-01

    The need for automated systems to monitor chemical and biochemical variables led to the definition of the EUREKA-EUROMAR project MERMAID. It was realized by several international scientific and industrial partners. Important components were automatic nutrient analyzers and remote-controlled samplers for toxic trace substances in addition to a high-performance data management system with bi-directional telemetry units for remote-controlled network operation. These modules were implemented in the MERMAID network consisting of three sea stations, two of them set up in the Elbe estuary, and one in the Elbe-influenced coastal zone. The latter was at the same time part of the BSH-network. The data were transmitted to shore and processed at GKSS and BSH. While in the preceding project phase the marine pollution network was established and tested, the last MERMAID phase covered its experimental operation. For this purpose, different modules were installed at the three stations. They incorporated meteorological, oceanographic, physical and chemical sensors in addition to automatic analyzers for phosphate, nitrite/nitrate and ammonium as well as specialized samplers for heavy metals and organic micropollutants. Variables were determined directly either continuously by in situ sensors or at variable time intervals by remote-controlled in situ analyzers, or they were determined indirectly by samplers allowing phase-separated multiple sampling with remote or event control of the sampling frequency. In this contribution, the results of nutrient and heavy metal concentration time series measured in 1995 and 1996 are presented together with corresponding meteorological and oceanographic variables. The examples indicate that the transfer of nutrients and contaminants in the estuary and in the coastal zone is strongly influenced by different short- and long-term events, i.e. freshwater discharge rates and wind action. Additionally, in summer, chemical and biological processes

  13. Chaotic scattering in an open vase-shaped cavity: Topological, numerical, and experimental results

    NASA Astrophysics Data System (ADS)

    Novick, Jaison Allen

    point to each "detector point". We then construct the wave function directly from these classical trajectories using the two-dimensional WKB approximation. The wave function is Fourier Transformed using a Fast Fourier Transform algorithm resulting in a spectrum in which each peak corresponds to an interpolated trajectory. Our predictions are based on an imagined experiment that uses microwave propagation within an electromagnetic waveguide. Such an experiment exploits the fact that under suitable conditions both Maxwell's Equations and the Schrodinger Equation can be reduced to the Helmholtz Equation. Therefore, our predictions, while compared to the electromagnetic experiment, contain information about the quantum system. Identifying peaks in the transmission spectrum with chaotic trajectories will allow for an additional experimental verification of the intermediate recursive structure. Finally, we summarize our results and discuss possible extensions of this project.

  14. Sodium laser guide star system at Lawrence Livermore National Laboratory: System description and experimental results

    SciTech Connect

    Avicola, K.; Brase, J.; Morris, J.

    1994-03-02

    The architecture and major system components of the sodium-layer kw guide star system at LLNL will be described, and experimental results reported. The subsystems include the laser system, the beam delivery system including a pulse stretcher and beam pointing control, the beam director, and the telescope with its adaptive-optics package. The laser system is one developed for the Atomic Vapor Laser Isotope Separation (AVLIS) Program. This laser system can be configured in various ways in support of the AVLIS program objectives, and was made available to the guide star program at intermittent times on a non-interference basis. The first light transmitted into the sky was in July of 1992, at a power level of 1. 1 kW. The laser pulse width is about 32 ns, and the pulse repetition rate was 26 kHz for the 1. 1 kW configuration and 13 kHz for a 400 W configuration. The laser linewidth is tailored to match the sodium D{sub 2} absorption line, and the laser system has active control of beam pointing and wavefront quality. Because of the short pulse length the sodium transition is saturated and the laser power is not efficiently utilized. For this reason a pulse stretcher was developed, and the results of this effort will be reported. The beam is delivered via an evacuated pipe from the laser building to the guide star site, a distance of about 100 meters, and then launched vertically. A beam director provides the means to track the sky in the full AO system, but was not used in the experiments reported here. The return signal is collected by a 1/2 meter telescope with the AO package. This telescope is located 5 meters from the km launch tube. Smaller packages for photometry, wavefront measurement, and spot image and motion analysis have been used. Although the unavailability of the AVLIS laser precluded a full AO system demonstration, data supporting feasibility and providing input to the system design for a Lick Observatory AO system was obtained.

  15. Electromagnetic (EM) earthquake precursor transmission and detection regarding experimental field and laboratory results.

    NASA Astrophysics Data System (ADS)

    Jones, Kenneth B., II; Saxton, Patrick

    2016-04-01

    Aside from understanding the animal kingdom reacting to a per-earthquake signal, a transmission source is apparent. The focus of this investigation is an electromagnetic emission approach and detection capable of becoming both practical and reliable to other plausible earthquake precursors. To better determine this method, several prototype magnetometers were devised and built with each successive version improving upon the next. Two twin (prototype #2) antennae were deployed to field settings outside the NE Texas town of Timpson, TX back in February, 2013 and very recent laboratory tests using the most refined (prototype #4) experimental antenna for detecting unconfined, granitic block fracturing. Field testing encompassed the small NE Texas town of Timpson, TX, which endured an earthquake phenomenon (May, 2012 - September, 2013). A rare sequence of events was strictly attributed to hydraulic fracturing activity in the immediate area all for hydrocarbon capture; thus, a chance to detect and record man-made earthquake activity. By swiveling two directional antennae at three locations, one mobile, the antennae could 'zero' in on a signal source until its pattern was well established and mapped, accordingly. Three signals were detected, two strong and one moderately strong, each with epicenter implications several kilometers from known seismological sites. Six months later, two M4s and a M2.4 earthquake hit over the 2013 Labor Day weekend. Hydraulic pump pressure increased deep Earth pore pressure, reduced friction, and displaced opposing tectonic stresses causing rock to fracture. This was the last earthquake sequence in the Timpson area, due to personal involvement and area citizens in contact with their state representatives. Well and drilling operations have since moved 40-50 miles SE of Timpson, TX and rare earthquake activity has now occurred there. Laboratory testing was next performed using cored granitic blocks and the latest, improved antenna with an

  16. Chlorine Stable Isotope Composition of Altered Oceanic Crust: Empirical and Experimental Results

    NASA Astrophysics Data System (ADS)

    Barnes, J.; Gardner, J. E.

    2010-12-01

    be ~ +2-3‰ heavier than those in which Cl bonds with 1+ cations (Schauble et al., 2003). These calculations have led to the hypothesis that silicates should have higher 37Cl/35Cl ratios than co-existing brines at room temperature (Schauble et al., 2003). Preliminary Cl isotope fractionation experiments between pargasitic amphibole and either seawater or brine (25 wt% NaCl solution) were run in cold-seal pressure vessels at 600°C and 500 bars. Preliminary results suggest that Δ37Clpargasite-Cl(aq) is within analytical error of the theoretically predicted fractionation factor, as well as measured δ37Cl values of AOC samples. Further work is planned to investigate the role of fluid-rock ratio and amphibole composition. Additional experimental data may allow us to infer the fluid-rock ratio and temperature during hydration of natural samples and to unravel the fluid histories recorded in the alteration minerals.

  17. Experimental determination of the solubility of iridium in silicate melts: Preliminary results

    NASA Technical Reports Server (NTRS)

    Borisov, Alexander; Dingwell, Donald B.; Oneill, Hugh ST.C.; Palme, Herbert

    1992-01-01

    Little is known of the geochemical behavior of iridium. Normally this element is taken to be chalcophile and/or siderophile so that during planetary differentiation processes, e.g., core formation, iridium is extracted from silicate phases into metallic phases. Experimental determination of the metal/silicate partition coefficient of iridium is difficult simply because it is so large. Also there are no data on the solubility behavior of iridium in silicate melts. With information on the solubility of iridium in silicate melts it is possible, in combination with experimental data for Fe-Ir alloys, to calculate the partition coefficient between a metallic phase and a silicate melt.

  18. Understanding how hydrodynamics affects particle transport in saturated fractures using modelling and experimental results

    NASA Astrophysics Data System (ADS)

    Cianflone, S.; Lakhian, V.; Dickson, S. E.

    2013-12-01

    poly(methyl methacrylate), thus creating a pseudo-2D fracture. Namely, the 2D fracture (x-y coordinates) is cut into the plastic using a laser printer, thus the z-coordinate is constant to a depth of 2.3 mm. Experiments using Acid Yellow 17, as a tracer, as well as fluorescent microspheres (42.5 nm and 525 nm, non-carboxylated to minimize attachment/detachment) will be performed in order to compare simulations and experimental results. Concentrations of the microspheres and tracer were measured at the effluent end of the fracture where the end cap housed an LED (400-470 nm) and an optical fibre attached to a spectrophotometer. Simulations suggest that in fractures where eddies occur, there is retention of smaller particles only when there is sufficient diffusion and a slow enough fluid velocity to allow them to enter the eddy. Otherwise, the particles exit the fracture earlier than typically expected when considering particle size exclusion and average fluid velocity. Further modelling results suggest that using bulk measurements (eg. mean aperture, mean fluid velocity, and measures of fracture roughness) to predict the resultant particulate outflow in a saturated fracture is difficult. We plan to include visualization experiments in order to draw further comparisons to the modelling results.

  19. Robotic Exploration and Science in Pits and Caves: Results from Three Years and Counting of Analog Field Experimentation

    NASA Astrophysics Data System (ADS)

    Wong, U. Y.; Whittaker, W. L.

    2015-10-01

    Robots are poised to access, investigate, and model planetary caves. We present the results of a multi-year campaign to develop robotic technologies for this domain, anchored by the most comprehensive analog field experimentation to date.

  20. OVERVIEW OF RECENT EXPERIMENTAL RESULTS FROM THE DIII-D ADVANCED TOKAMAK PROGRAM

    SciTech Connect

    BURRELL,KH

    2002-11-01

    OAK A271 OVERVIEW OF RECENT EXPERIMENTAL RESULTS FROM THE DIII-D ADVANCED TOKAMAK PROGRAM. The DIII-D research program is developing the scientific basis for advanced tokamak (AT) modes of operation in order to enhance the attractiveness of the tokamak as an energy producing system. Since the last International Atomic Energy Agency (IAEA) meeting, the authors have made significant progress in developing the building blocks needed for AT operation: (1) the authors have doubled the magnetohydrodynamic (MHD) stable tokamak operating space through rotational stabilization of the resistive wall mode; (2) using this rotational stabilization, they have achieved {beta}{sub N}H{sub 89} {le} 10 for 4 {tau}{sub E} limited by the neoclassical tearing mode; (3) using real-time feedback of the electron cyclotron current drive (ECCD) location, they have stabilized the (m,n) = (3,2) neoclassical tearing mode and then increased {beta}{sub T} by 60%; (4) they have produced ECCD stabilization of the (2,1) neoclassical tearing mode in initial experiments; (5) they have made the first integrated AT demonstration discharges with current profile control using ECCD; (6) ECCD and electron cyclotron heating (ECH) have been used to control the pressure profile in high performance plasmas; and (7) they have demonstrated stationary tokamak operation for 6.5 s (36 {tau}{sub E}) at the same fusion gain parameter of {beta}{sub N}H{sub 89}/q{sub 95}{sup 2} {approx} 0.4 as ITER but at much higher q{sub 95} = 4.2. They have developed general improvements applicable to conventional and advanced tokamak operating modes: (1) they have an existence proof of a mode of tokamak operation, quiescent H-mode, which has no pulsed, ELM heat load to the divertor and which can run for long periods of time (3.8 s or 25 {tau}{sub E}) with constant density and constant radiation power; (2) they have demonstrated real-time disruption detection and mitigation for vertical disruption events using high pressure gas jet

  1. The Abiotic Fixation of Nitrogen on Terrestrial Planets: Experimental Results and their Implications.

    NASA Astrophysics Data System (ADS)

    Summers, David; Khare, Bishun; Basa, Ranor

    The abiotic fixation of nitrogen is critical to understanding habitability, planetary evolution and the potential origin of life on terrestrial planets. A non-biological source of fixed nitrogen, in a biochemically accessible form, is necessary for the origin and early evolution of life. Loss of atmospheric nitrogen can result in an incapacity to sustain liquid surface water (as on Mars) and impact planetary habitability. The products of fixation will also impact the geochemistry. Shock heating of a non-reducing atmosphere, by meteors or lighting, will produce NO. This process has been well studied. However, our understanding of the subsequent reactions of NO has been, in the past, theoretical. It was postulated that NO was photochemically converted to HNO which then dissolves in surface waters and reacts to form nitrate and nitrite. This chemistry has now been studied experimentally. Our work has observed that there are multiple pathways for the fixation. One pathway observed is consistent with the theoretically predicted route via the formation of HNO. Interestingly, this pathway is coupled to photochemical formation of formaldehyde from CO through the formation of HCO. In the presence of liquid water, this pathway leads to the formation of nitrate and nitrite. In the presence of water vapor, but no liquid water, HNO appears to mostly dimerize to form N2 O. A second pathway involves the formation of NO2 from CO2 and NO. This pathway becomes more dominant without water, but the reaction of NO2 with any form of water, even just adsorbed water, can lead to nitric acid. Finally, with FeS suspended in liquid water, the direct reduction of NO to ammonia is observed. This last pathway represents the most efficient way to reduced nitrogen, with product yields in excess of 50% (nitrite/nitrate, from the first two pathways can also be reduced to ammonia thought the overall efficiency suffers). This has implications for a number of planets. For example, chemistry in the

  2. Multiple Measures of Juvenile Drug Court Effectiveness: Results of a Quasi-Experimental Design

    ERIC Educational Resources Information Center

    Rodriguez, Nancy; Webb, Vincent J.

    2004-01-01

    Prior studies of juvenile drug courts have been constrained by small samples, inadequate comparison groups, or limited outcome measures. The authors report on a 3-year evaluation that examines the impact of juvenile drug court participation on recidivism and drug use. A quasi-experimental design is used to compare juveniles assigned to drug court…

  3. Comparison of Breast Health Teaching Methods for Adolescent Females: Results of a Quasi-Experimental Study

    ERIC Educational Resources Information Center

    Evans, Retta R.; Horton, Jacqueline A.; Ahmad, Wajih A.; Davies, Susan L.; Snyder, Scott W.; Macrina, David M.

    2013-01-01

    Purpose: A breast health educational program was administered in two public high school settings in north Alabama to subjects enrolled in health related courses. The purpose of this quasi-experimental study was to determine if teaching breast health with or without interactive learning would affect the breast health knowledge and beliefs of…

  4. Experimental warming delays autumn senescence in a boreal spruce bog: Initial results from the SPRUCE experiment

    NASA Astrophysics Data System (ADS)

    Richardson, Andrew; Furze, Morgan; Aubrecht, Donald; Milliman, Thomas; Nettles, Robert; Krassovski, Misha; Hanson, Paul

    2016-04-01

    Phenology is considered one of the most robust indicators of the biological impacts of global change. In temperate and boreal regions, long-term data show that rising temperatures are advancing spring onset (e.g. budburst and flowering) and delaying autumn senescence (e.g. leaf coloration and leaf fall) in a wide range of ecosystems. While warm and cold temperatures, day length and insolation, precipitation and water availability, and other factors, have all been shown to influence plant phenology, the future response of phenology to rising temperatures and elevated CO2 still remains highly uncertain because of the challenges associated with conducting realistic manipulative experiments to simulate future environmental conditions. At the SPRUCE (Spruce and Peatland Responses Under Climatic and Environmental Change) experiment in the north-central United States, experimental temperature (0 to +9° C above ambient) and CO2 (ambient and elevated) treatments are being applied to mature, and intact, Picea mariana-Sphagnum spp. bog communities in their native habitat through the use of ten large (approximately 12 m wide, 10 m high) open-topped enclosures. We are tracking vegetation green-up and senescence in these chambers, at both the individual and whole-community level, using repeat digital photography. Within each chamber, digital camera images are recorded every 30 minutes and uploaded to the PhenoCam (http://phenocam.sr.unh.edu) project web page, where they are displayed in near-real-time. Image processing is conducted nightly to extract quantitative measures of canopy color, which we characterize using Gcc, the green chromatic coordinate. Data from a camera mounted outside the chambers (since November 2014) indicate strong seasonal variation in Gcc for both evergreen shrubs and trees. Shrub Gcc rises steeply in May and June, and declines steeply in September and October. By comparison, tree Gcc rises gradually from March through June, and declines gradually from

  5. White-light Interferometry using a Channeled Spectrum: II. Calibration Methods, Numerical and Experimental Results

    NASA Technical Reports Server (NTRS)

    Zhai, Chengxing; Milman, Mark H.; Regehr, Martin W.; Best, Paul K.

    2007-01-01

    In the companion paper, [Appl. Opt. 46, 5853 (2007)] a highly accurate white light interference model was developed from just a few key parameters characterized in terms of various moments of the source and instrument transmission function. We develop and implement the end-to-end process of calibrating these moment parameters together with the differential dispersion of the instrument and applying them to the algorithms developed in the companion paper. The calibration procedure developed herein is based on first obtaining the standard monochromatic parameters at the pixel level: wavenumber, phase, intensity, and visibility parameters via a nonlinear least-squares procedure that exploits the structure of the model. The pixel level parameters are then combined to obtain the required 'global' moment and dispersion parameters. The process is applied to both simulated scenarios of astrometric observations and to data from the microarcsecond metrology testbed (MAM), an interferometer testbed that has played a prominent role in the development of this technology.

  6. Experimental and computational results for 5 degree blunt cones with shock generators at high velocity

    NASA Technical Reports Server (NTRS)

    Strawa, A. W.; Molvik, G. A.; Yates, L. A.; Cornelison, C.

    1989-01-01

    Experiments and computations have been performed under laminar conditions in air on 5-deg blunt cones at velocities of 5 km/s and 6 km/s and at Reynolds numbers of 100,000 and 1 million. The computations were performed using ideal-, equilibrium- and nonequilibrium-chemistry models for air. At the conditions of the tests, the aerodynamic coefficients are sensitive to the real-gas effects present, and both experimental and computational aerodynamic coefficients show real-gas and nonlinear effects. The nonequilibrium computations show that a large amount of oxygen is dissociated in the blunt nose region of the flow and much of the oxygen remains dissociated over the entire length of the body, providing an insight into the source of the observed effects in the aerodynamic coefficients. The experimental and computational shock-shapes are in good agreement.

  7. Cold Climate Foundation Retrofit Experimental Hygrothermal Performance. Cloquet Residential Research Facility Laboratory Results

    SciTech Connect

    Goldberg, Louise F.; Harmon, Anna C.

    2015-04-09

    This project was funded jointly by the National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL). ORNL focused on developing a full basement wall system experimental database to enable others to validate hygrothermal simulation codes. NREL focused on testing the moisture durability of practical basement wall interior insulation retrofit solutions for cold climates. The project has produced a physically credible and reliable long-term hygrothermal performance database for retrofit foundation wall insulation systems in zone 6 and 7 climates that are fully compliant with the performance criteria in the 2009 Minnesota Energy Code. These data currently span the period from November 10, 2012 through May 31, 2014 and are anticipated to be extended through November 2014. The experimental data were configured into a standard format that can be published online and that is compatible with standard commercially available spreadsheet and database software.

  8. Behavior of spinning laminated composite plates with initial twist-experimental vibrations, strain, and deflection results

    NASA Technical Reports Server (NTRS)

    Lapid, A. J.; Kosmatka, J. B.; Mehmed, O.

    1993-01-01

    The experimental behavior of spinning, pre-twisted laminated composite plates was investigated. The purpose of these experiments was to establish an experimental database consisting of strain, deflections, and natural frequencies as a function of rotational velocity. Six different plate sets were tested, that included three different stacking sequences (two symmetric, one asymmetric), two different initial twist levels (0 deg, 30 deg), and two different initial twist axis locations (midchord, quarter-chord). The plates were spin tested at four different combinations of pitch and sweep. It was observed that the location of the pretwist axis and the level of pretwist greatly affects the strain and deflections of the spinning plate, while only the pretwist level affects the measured natural frequencies.

  9. Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

    NASA Astrophysics Data System (ADS)

    Otsuji, K.; Sawada, T.; Satoh, S.; Kanda, S.; Matsumura, H.; Kondo, S.; Otsubo, K.

    Oxygen concentration and separation is an essential factor for air recycling in a CELSS. Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of O2 from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested.

  10. Elasticity of mechanical oscillators in nonequilibrium steady states: Experimental, numerical, and theoretical results

    NASA Astrophysics Data System (ADS)

    Conti, Livia; De Gregorio, Paolo; Bonaldi, Michele; Borrielli, Antonio; Crivellari, Michele; Karapetyan, Gagik; Poli, Charles; Serra, Enrico; Thakur, Ram-Krishna; Rondoni, Lamberto

    2012-06-01

    We study experimentally, numerically, and theoretically the elastic response of mechanical resonators along which the temperature is not uniform, as a consequence of the onset of steady-state thermal gradients. Two experimental setups and designs are employed, both using low-loss materials. In both cases, we monitor the resonance frequencies of specific modes of vibration, as they vary along with variations of temperatures and of temperature differences. In one case, we consider the first longitudinal mode of vibration of an aluminum alloy resonator; in the other case, we consider the antisymmetric torsion modes of a silicon resonator. By defining the average temperature as the volume-weighted mean of the temperatures of the respective elastic sections, we find out that the elastic response of an object depends solely on it, regardless of whether a thermal gradient exists and, up to 10% imbalance, regardless of its magnitude. The numerical model employs a chain of anharmonic oscillators, with first- and second-neighbor interactions and temperature profiles satisfying Fourier's Law to a good degree. Its analysis confirms, for the most part, the experimental findings and it is explained theoretically from a statistical mechanics perspective with a loose notion of local equilibrium.

  11. Experimental results from RO-PRO: a next generation system for low-energy desalination.

    PubMed

    Achilli, Andrea; Prante, Jeri L; Hancock, Nathan T; Maxwell, Eric B; Childress, Amy E

    2014-06-01

    A pilot system was designed and constructed to evaluate reverse osmosis (RO) energy reduction that can be achieved using pressure-retarded osmosis (PRO). The RO-PRO experimental system is the first known system to utilize energy from a volume of water transferred from atmospheric pressure to elevated pressure across a semipermeable membrane to prepressurize RO feedwater. In other words, the system demonstrated that pressure could be exchanged between PRO and RO subsystems. Additionally, the first experimental power density data for a RO-PRO system is now available. Average experimental power densities for the RO-PRO system ranged from 1.1 to 2.3 W/m2. This is higher than previous river-to-sea PRO pilot systems (1.5 W/m2) and closer to the goal of 5 W/m2 that would make PRO an economically feasible technology. Furthermore, isolated PRO system testing was performed to evaluate PRO element performance with higher cross-flow velocities and power densities exceeding 8 W/m2 were achieved with a 28 g/L NaCl draw solution. From this empirical data, inferences for future system performance can be drawn that indicate future RO-PRO systems may reduce the specific energy requirements for desalination by ∼1 kWh/m3. PMID:24798068

  12. Modelling Study at Kutlular Copper FIELD with Spat This Study, Evaluation Steps of Copper Mine Field SP Data Are Shown How to Reach More Accurate Results for SP Inversion Method.

    NASA Astrophysics Data System (ADS)

    Sahin, O. K.; Asci, M.

    2014-12-01

    At this study, determination of theoretical parameters for inversion process of Trabzon-Sürmene-Kutlular ore bed anomalies was examined. Making a decision of which model equation can be used for inversion is the most important step for the beginning. It is thought that will give a chance to get more accurate results. So, sections were evaluated with sphere-cylinder nomogram. After that, same sections were analyzed with cylinder-dike nomogram to determine the theoretical parameters for inversion process for every single model equations. After comparison of results, we saw that only one of them was more close to parameters of nomogram evaluations. But, other inversion result parameters were different from their nomogram parameters.

  13. Boundary conditions for creeping flow along periodic or random rough surfaces : experimental and theoretical results

    NASA Astrophysics Data System (ADS)

    Lecoq, Nicolas

    2012-12-01

    Hydrodynamic interactions between particles and walls are relevant for the open problem of specifying boundary conditions for suspension flows. The Reynolds number around a small particle close to a wall is usually low and creeping flow equations apply. From the solution of these equations, the drag coefficient on a sphere becomes infinite when the gap between the sphere and a smooth wall vanishes, so that contact may not occur. Physically, the drag is finite because of various reasons, one of them being the particle and wall roughness. Then, for vanishing gap, even though some layers of fluid molecules may be left between the particle and wall roughness peaks, it may conventionally be said that contact occurs. In this paper, we are considering the example of a smooth sphere moving towards a rough wall. The roughness considered here consist of random rough planes or parallel periodic wedges, the characteristic length of which is small compared with the sphere radius. This problem is considered both experimentally and theoretically. The motion of a millimetre size bead settling towards a corrugated horizontal wall in a viscous oil is measured with laser interferometry giving an accuracy on the displacement of 0.2μm. Several random rough planes and wedge shaped walls were used, with various wavelengths and wedge angles. From the results, it is observed that the velocity of the sphere is, except for small gaps, similar to that towards a smooth plane that is shifted down from the top of corrugations. For the periodic wedges, the creeping flow is calculated as a series in the slope of the roughness grooves. The convergence of the series for the shift distance in term of the slope is accelerated by use of Euler transformation and of the existence of a limit for large slope. The cases of a flow along and across the grooves are considered separately. The shift is larger in the former case. Slightly flattened tops of the wedges used in experiments are also considered in

  14. OVERVIEW OF RECENT EXPERIMENTAL RESULTS FROM THE DIII-D ADVANCED TOKAMAK PROGRAM

    SciTech Connect

    BURRELL,HK

    2002-11-01

    OAK A271 OVERVIEW OF RECENT EXPERIMENTAL RESULTS FROM THE DIII-D ADVANCED TOKAMAK PROGRAM. The DIII-D research program is developing the scientific basis for advanced tokamak (AT) modes of operation in order to enhance the attractiveness of the tokamak as an energy producing system. Since the last International Atomic Energy Agency (IAEA) meeting, they have made significant progress in developing the building blocks needed for AT operation: (1) they have doubled the magnetohydrodynamic (MHD) stable tokamak operating space through rotational stabilization of the resistive wall mode; (2) using this rotational stabilization, they have achieved {beta}{sub N}H{sub 89} {ge} 10 for 4 {tau}{sub E} limited by the neoclassical tearing mode; (3) using real-time feedback of the electron cyclotron current drive (ECCD) location, they have stabilized the (m,n) = (3,2) neoclassical tearing mode and then increased {beta}{sub T} by 60%; (4) they have produced ECCD stabilization of the (2,1) neoclassical tearing mode in initial experiments; (5) they have made the first integrated AT demonstration discharges with current profile control using ECCD; (6) ECCD and electron cyclotron heating (ECH) have been used to control the pressure profile in high performance plasmas; and (7) they have demonstrated stationary tokamak operation for 6.5 s (36 {tau}{sub E}) at the same fusion gain parameter of {beta}{sub N}H{sub 89}/q{sub 95}{sup 2} {approx} 0.4 as ITER but at much higher q{sub 95} = 4.2. The authors have developed general improvements applicable to conventional and advanced tokamak operating modes: (1) they have an existence proof of a mode of tokamak operation, quiescent H-mode, which has no pulsed, ELM heat load to the divertor and which can run for long periods of time (3.8 s or 25 {tau}{sub E}) with constant density and constant radiated power; (2) they have demonstrated real-time disruption detection and mitigation for vertical disruption events using high pressure gas jet

  15. Magma Mixing by Chaotic Dynamics: Results from a New Experimental Device

    NASA Astrophysics Data System (ADS)

    de Campos, C. P.; Perugini, D.; Ingrisch, W. E.; Dingwell, D. B.; Poli, G.

    2009-12-01

    In this work we present a new experimental device, based on the Journal Bearing System (JBS), to perform chaotic mixing of high viscosity melts under controlled fluid-dynamics and temperature conditions. The system consists of an outer cylinder, hosting the melts of interest and, an inner cylinder, eccentrically located, whose motions are independent. This way the development of chaotic streamlines in the mixing system is induced. An experiment was performed, using as end-members a peralkaline haplogranite (HPG8) and a mafic melt, corresponding to the 1 atm eutectic composition in the An-Di binary system. The two melts were stirred together in the JBS for ca. two hours at 1,400°C under laminar fluid dynamic condition (Re of the order of 10-7). Viscosity ratio between the two melts, at the beginning of the experiment, was of the order of 1,000. Analyses of experimental samples revealed, at short length scale (of the order of μm), a complex pattern of mixing structures. These consisted of an intimate distribution of filaments of the two melts, a typical feature in rocks produced by magma mixing processes. Stretching and folding dynamics between both melts induced chaotic flow fields and generated wide compositional interfaces. This way, chemical diffusion processes acted efficiently, producing melts with highly heterogeneous compositions. Despite a short running time, very low Re and a high viscosity ratio, a clear modulation of compositional fields has been obtained (fig.1). This indicates that chaotic mixing can be a very efficient process in enhancing the compositional variability in igneous systems, even under extreme rheological conditions and laminar fluid-dynamics. The excellence of our experimental device to replicate natural magma mixing features may open new frontiers in the study of this important petrological and volcanological process. Figure 1

  16. Mixing Silicate Melts with High Viscosity Contrast by Chaotic Dynamics: Results from a New Experimental Device

    NASA Astrophysics Data System (ADS)

    de Campos, Cristina; Perugini, Diego; Ertel-Ingrisch, Werner; Dingwell, Donald B.; Poli, Giampiero

    2010-05-01

    A new experimental device has been developed to perform chaotic mixing between high viscosity melts under controlled fluid-dynamic conditions. The apparatus is based on the Journal Bearing System (JBS). It consists of an outer cylinder hosting the melts of interest and an inner cylinder, which is eccentrically located. Both cylinders can be independently moved to generate chaotic streamlines in the mixing system. Two experiments were performed using as end-members different proportions of a peralkaline haplogranite and a mafic melt, corresponding to the 1 atm eutectic composition in the An-Di binary system. The two melts were stirred together in the JBS for ca. two hours, at 1,400° C and under laminar fluid dynamic condition (Re of the order of 10-7). The viscosity ratio between the two melts, at the beginning of the experiment, was of the order of 103. Optical analyses of experimental samples revealed, at short length scale (of the order of μm), a complex pattern of mixed structures. These consisted of an intimate distribution of filaments; a complex inter-fingering of the two melts. Such features are typically observed in rocks thought to be produced by magma mixing processes. Stretching and folding dynamics between the melts induced chaotic flow fields and generated wide compositional interfaces. In this way, chemical diffusion processes become more efficient, producing melts with highly heterogeneous compositions. A remarkable modulation of compositional fields has been obtained by performing short time-scale experiments and using melts with a high viscosity ratio. This indicates that chaotic mixing of magmas can be a very efficient process in modulating compositional variability in igneous systems, especially under high viscosity ratios and laminar fluid-dynamic regimes. Our experimental device may replicate magma mixing features, observed in natural rocks, and therefore open new frontiers in the study of this important petrologic and volcanological process.

  17. Cavity-Enhanced Frequency-Agile Rapid Scanning (fars) Spectroscopy: Experimental Realizations and Measurement Results

    NASA Astrophysics Data System (ADS)

    Long, David A.; Truong, Gar-Wing; Zee, Roger Van; Plusquellic, David F.; Hodges, Joseph T.

    2013-06-01

    We present a series of experimental realizations of cavity-enhanced, frequency-agile rapid scanning (FARS) spectroscopy using distributed feedback diode lasers, external cavity diode lasers, and ultra-narrow linewidth fiber lasers. FARS offers a scanning rate which is limited only by the cavity response time itself as well as a microwave-level frequency axis. Finally, it allows for an absorption sensitivity which is one of the highest ever reported. These realizations offer a range of applications from low-cost field measurements of trace gases to laboratory-based metrology.

  18. Preliminary experimental results of gas recycling subsystems except carbon dioxide concentration

    NASA Technical Reports Server (NTRS)

    Otsuji, K.; Sawada, T.; Satoh, S.; Kanda, S.; Matsumura, H.; Kondo, S.; Otsubo, K.

    1987-01-01

    Oxygen concentration and separation is an essential factor for air recycling in a controlled ecological life support system (CELSS). Furthermore, if the value of the plant assimilatory quotient is not coincident with that of the animal respiratory quotient, the recovery of oxygen from the concentrated CO2 through chemical methods will become necessary to balance the gas contents in a CELSS. Therefore, oxygen concentration and separation equipment using Salcomine and O2 recovery equipment, such as Sabatier and Bosch reactors, were experimentally developed and tested.

  19. Design considerations and experimental results of a 100 W, 500 000 rpm electrical generator

    NASA Astrophysics Data System (ADS)

    Zwyssig, C.; Kolar, J. W.

    2006-09-01

    Mesoscale gas turbine generator systems are a promising solution for high energy and power density portable devices. This paper focuses on the design of a 100 W, 500 000 rpm generator suitable for use with a gas turbine. The design procedure selects the suitable machine type and bearing technology, and determines the electromagnetic characteristics. The losses caused by the high frequency operation are minimized by optimizing the winding and the stator core material. The final design is a permanent-magnet machine with a volume of 3 cm3 and experimental measurements from a test bench are presented.

  20. Literature review and experimental results for a cylinder with perforations and protrusions at high Reynolds numbers

    NASA Technical Reports Server (NTRS)

    Jones, G. S.; Horvath, T. J.; Stainback, P. C.; Beasley, W. D.; Mcghee, R. J.

    1987-01-01

    The NASA Langley Low Turbulence Pressure Tunnel has been used to conduct an experimental study of the flow around a series of circular cylinders; the models used consisted of a baseline, smooth cylinder together with a cylinder that could be reconfigured with six different arrangements of two types of surface irregularity. Mean lift and drag forces were measured on all seven model configurations, and correlations were made between unsteady pressure in the wake region and fluctuating lift forces, in order to identify coherent structures.

  1. Results of experimental tests and calibrations of the surface neutron moisture measurement probe

    SciTech Connect

    Watson, W.T.; Bussell, J.H., Westinghouse Hanford

    1996-08-13

    The surface neutron moisture probe has been tested both to demonstrate that is is able to operate in the expected in-tank temperature and gamma-ray fields and to provide detector responses to known moisture concentration materials. The probe will properly function in a simultaneous high temperature (80 degrees C) and high gamma radiation field (210 rad/hr)environment. Comparisons between computer model predicted and experimentally measured detector responses to changes in moisture provide a basis for the probe calibration to in-tank moisture concentrations.

  2. Charging characteristics of materials: Comparison of experimental results with simple analytical models

    NASA Technical Reports Server (NTRS)

    Purvis, C. K.; Stevens, N. J.; Oglebay, J. C.

    1977-01-01

    An understanding of the behavior of materials, of dielectrics in particular, under charged particle bombardment is essential to the prediction and prevention of the adverse effects of spacecraft charging. A one-dimensional model for charging of samples in a test facility was used in conjunction with experimental data taken to develop "material charging characteristics" for silvered Teflon. These characteristics were then used in a one-dimensional model for charging in space to examine expected response. Relative charging rates as well as relative charging levels for silvered Teflon and metal are discussed.

  3. Results of aircraft open-loop tests of an experimental magnetic leader cable system for guidance during roll-out and turnoff

    NASA Technical Reports Server (NTRS)

    Bundick, W. Thomas; Middleton, David B.; Poole, William L.

    1990-01-01

    An experimental magnetic leader cable (MLC) system designed to measure aircraft lateral displacement from centerline and heading relative to centerline during rollout, turnoff, and taxi was tested at NASA's Wallops Flight Facility using NASA's Transport System Research Vehicle (TSRV), a modified B-737. The MLC system consisted of ground equipment that produced a magnetic field about a wire along runway centerline and airborne equipment that detected the strength and direction of this field and computed displacement and heading. Results of these tests indicate that estimates of aircraft displacement from centerline produced by the magnetic leader cable system using either of the two algorithms appear to be adequate for use by an automatic control system during rollout, turnoff, and taxi. Estimates of heading, however, are not sufficiently accurate for use, probably because of distortion of the magnetic field by the metal aircraft.

  4. Cold Climate Foundation Retrofit Experimental Hygrothermal Performance: Cloquet Residential Research Facility Laboratory Results

    SciTech Connect

    Goldberg, Louise F.; Harmon, Anna C.

    2015-04-01

    Thermal and moisture problems in existing basements create a unique challenge because the exterior face of the wall is not easily or inexpensively accessible. This approach addresses thermal and moisture management from the interior face of the wall without disturbing the exterior soil and landscaping. the interior and exterior environments. This approach has the potential for improving durability, comfort, and indoor air quality. This project was funded jointly by the National Renewable Energy Laboratory (NREL) and Oak Ridge National Laboratory (ORNL). ORNL focused on developing a full basement wall system experimental database to enable others to validate hygrothermal simulation codes. NREL focused on testing the moisture durability of practical basement wall interior insulation retrofit solutions for cold climates. The project has produced a physically credible and reliable long-term hygrothermal performance database for retrofit foundation wall insulation systems in zone 6 and 7 climates that are fully compliant with the performance criteria in the 2009 Minnesota Energy Code. The experimental data were configured into a standard format that can be published online and that is compatible with standard commercially available spreadsheet and database software.

  5. Toxicology of chemical mixtures: experimental approaches, underlying concepts, and some results.

    PubMed

    Yang, R S; Hong, H L; Boorman, G A

    1989-12-01

    The toxicology of chemical mixtures will be the toxicology of the 1990s and beyond. While this branch of toxicology most closely reflects the actual human exposure situation, there is yet no standard protocol or consensus methodology for investigating the toxicology of mixtures. Thus, in this emerging science, experimentation is required just to develop a broadly applicable evaluation system. Several examples are discussed to illustrate the different experimental designs and the concepts behind each. These include the health effects studies of Love Canal soil samples, the Lake Ontario Coho salmon, the water samples repurified from secondary sewage in the city of Denver Potable Water Reuse Demonstration Plant, and the National Toxicology Program (NTP) effort on a mixture of 25 frequently detected groundwater contaminants derived from hazardous waste disposal sites. In the last instance, an extensive research program has been ongoing for the last 2 years at the NTP, encompassing general toxicology, immunotoxicology, developmental and reproductive toxicology, biochemical toxicology, myelotoxicology, genetic toxicology, neurobehavioral toxicology, and hepato- and renal toxicology. PMID:2690403

  6. Toxicology of chemical mixtures: Experimental approaches, underlying concepts, and some results

    SciTech Connect

    Yang, R.S.; Long, H.L.; Boorman, G.A.

    1990-07-01

    The toxicology of chemical mixtures will be the toxicology of the 1990s and beyond. While this branch of toxicology most closely reflects the actual human exposure situation, as yet there is no standard protocol or consensus methodology for investigating the toxicology of mixtures. Thus, in this emerging science, experimentation is required just to develop a broadly applicable evaluation system. Several examples are discussed to illustrate the different experimental designs and the concepts behind each. These include the health effects studies of Love Canal soil samples, the Lake Ontario Coho salmon, the water samples repurified from secondary sewage in the city of Denver Potable Water Reuse Demonstration Plant, and the National Toxicology Program (NTP) effort on a mixture of 25 frequently detected groundwater contaminants derived from hazardous waste disposal sites. In the last instance, an extensive research program has been ongoing for the last two years at the NTP, encompassing general toxicology, immunotoxicology, developmental and reproductive toxicology, biochemical toxicology, myelotoxicology, genetic toxicology, neurobehavioral toxicology, and hepato- and renal toxicology.

  7. Energy Transfer with Hydrogen and Superconductivity - The Review of the First Experimental Results

    NASA Astrophysics Data System (ADS)

    Vysotsky, V. S.; Antyukhov, I. V.; Firsov, V. P.; Blagov, E. V.; Kostyuk, V. V.; Nosov, A. A.; Fetisov, S. S.; Zanegin, S. Yu.; Rachuk, V. S.; Katorgin, B. I.

    The transfer of massive amounts of both electrical and chemical power over long distances will present a major challenge for the global energy enterprise in future. Attraction of hydrogen is apparent as a chemical energy agent, possessing among the highest energy density content of various common fuels, whose combustive "waste" is simply water. The usage of "gratis" cold to cool a superconducting cable made of proper superconductor permits to deliver extra electrical power with the same line. This, rather old theoretical idea recently found its experimental realization. The team of Russian institutes and organizations with using Italian-produced MgB2 wire has made and successfully tested two hybrid energy transfer lines with liquid hydrogen as a chemical source of power and superconducting cable as a source of electricity. The first line has been tested in 2011. It has length ∼10 m, maximum liquid hydrogen flow ∼250 g/s and maximum current of MgB2 superconducting cable 2600 A @ 20K. This test was the first experimental proof of conception of the hybrid energy transfer line. The second line has been tested in October 2013. It has length ∼30 m. The new MgB2 cable has critical current at 21 K ∼3500 A and successfully passed high voltage DC test of 50 kV. New hydrogen cryostat has three sections with different types of thermal insulation in each section. The idea of hybrid energy transfer is formulated and details of first experiments are reviewed.

  8. Adaptive wave field synthesis for active sound field reproduction: experimental results.

    PubMed

    Gauthier, Philippe-Aubert; Berry, Alain

    2008-04-01

    Sound field reproduction has applications in music reproduction, spatial audio, sound environment reproduction, and experimental acoustics. Sound field reproduction can be used to artificially reproduce the spatial character of natural hearing. The objective is then to reproduce a sound field in a real reproduction environment. Wave field synthesis (WFS) is a known open-loop technology which assumes that the reproduction environment is anechoic. The room response thus reduces the quality of the physical sound field reproduction by WFS. In recent research papers, adaptive wave field synthesis (AWFS) was defined as a potential solution to compensate for these quality reductions from which WFS objective performance suffers. In this paper, AWFS is experimentally investigated as an active sound field reproduction system with a limited number of reproduction error sensors to compensate for the response of the listening environment. Two digital signal processing algorithms for AWFS are used for comparison purposes, one of which is based on independent radiation mode control. AWFS performed propagating sound field reproduction better than WFS in three tested reproduction spaces (hemianechoic chamber, standard laboratory space, and reverberation chamber). PMID:18397007

  9. Transmission and phase balancing of alternating phase-shifting masks (5x): theoretical and experimental results

    NASA Astrophysics Data System (ADS)

    Griesinger, Uwe A.; Pforr, Rainer; Knobloch, Juergen; Friedrich, Christoph M.

    1999-12-01

    Dual trench alternating phase shifting masks with an optimized value of the so-called shallow trench depth represents an interesting approach to overcome aerial image imbalances. In order to get a better understanding of the possibilities and limits of this approach, especially for 5X reduction, theoretical and experimental investigations were accomplished. In this paper experimental data obtained from 5X dual trench type alternating PSMs, using DUV-lithography are introduced and compared with 3D-mask simulations. The masks were fabricated with different etch depths and contain parts of typical DRAM patterns. Besides the transmission balancing also the phase balancing has an important influence on the effective process window of an alternating PSM. The effective phase error can be measured with an AIMS-system (MSM100). The comparison with simulated data allows the determination of the phase error. In a second step the influence of different balancing methods on phase and transmission were investigated with the TEMPEST mask simulator for unpolarized light. The optimization of the balancing with respect to the CD-bias, undercut and etch depth will be shown and a first approach of a sensitivity analysis will be presented.

  10. Fuel performance under normal PWR conditions: A review of relevant experimental results and models

    NASA Astrophysics Data System (ADS)

    Charles, M.; Lemaignan, C.

    1992-06-01

    Experiments conducted at Grenoble (CEA/DRN) over the past 20 years in the field of nuclear fuel behaviour are reviewed. Of particular concern is the need to achieve a comprehensive understanding of and subsequently overcome the limitations associated with high burnup and load-following conditions (pellet-cladding interaction (PCI), fission gas release (FGR), water-side corrosion). A general view is given of the organization of research work as well as some experimental details (irradiation, postirradiation examination — PIE). Based on various experimental programmes (Cyrano, Medicis, Anemone, Furet, Tango, Contact, Cansar, Hatac, Flog, Decor), the main contributions of the thermomechanical behaviour of a PWR fuel rod are described: thermal conductivity, in-pile densification, swelling, fission gas release in steady state and moderate transient conditions, gap thermal conductance, formation of primary and secondary ridges under PCI conditions. Specific programmes (Gdgrif, Thermox, Grimox) are devoted to the behaviour of particular fuels (gadolinia-bearing fuel, MOX fuel). Moreover, microstructure-based studies have been undertaken on fission gas release (fine analysis of the bubble population inside irradiated fuel samples), and on cladding behaviour (PCI related studies on stress-corrosion cracking (SCO, irradiation effects on zircaloy microstructure).

  11. Emissivity modeling of metals during the growth of oxide film and comparison of the model with experimental results.

    PubMed

    Iuchi, Tohru; Furukawa, Tohru; Wada, Shigenobu

    2003-05-01

    Emissivity modeling of metals has been developed to elucidate behavior during the growth of oxide film, and the modeling results have been compared with experimental results. To express emissivities, pseudo-optical constants of a bare metal and of an oxide film obtained by an elipsometer are substituted into the model equations. Emissivity behavior during the growth of an oxide film upon the surface of a specimen is shown in terms of spectral, directional, and polarized characteristics, and it coincides with the experimental results, both quantitatively and qualitatively. The modeling is simple and provides useful guidance for the development of emissivity-compensated radiation thermometry. PMID:12737463

  12. Grading More Accurately

    ERIC Educational Resources Information Center

    Rom, Mark Carl

    2011-01-01

    Grades matter. College grading systems, however, are often ad hoc and prone to mistakes. This essay focuses on one factor that contributes to high-quality grading systems: grading accuracy (or "efficiency"). I proceed in several steps. First, I discuss the elements of "efficient" (i.e., accurate) grading. Next, I present analytical results…

  13. Accurate evaluation of homogenous and nonhomogeneous gas emissivities

    NASA Technical Reports Server (NTRS)

    Tiwari, S. N.; Lee, K. P.

    1984-01-01

    Spectral transmittance and total band adsorptance of selected infrared bands of carbon dioxide and water vapor are calculated by using the line-by-line and quasi-random band models and these are compared with available experimental results to establish the validity of the quasi-random band model. Various wide-band model correlations are employed to calculate the total band absorptance and total emissivity of these two gases under homogeneous and nonhomogeneous conditions. These results are compared with available experimental results under identical conditions. From these comparisons, it is found that the quasi-random band model can provide quite accurate results and is quite suitable for most atmospheric applications.

  14. [Experimental results of intra-osseous pressure in various surgical procedures of the long bones].

    PubMed

    Heim, D

    1995-04-01

    The generation of intramedullary pressure in medullary nailing and total hip and knee replacement is now well-known. This pressure increase is generally recognized as an important factor in local and systemic bone marrow embolization. In various clinical and experimental studies methods for reducing the intramedullary pressure build-up have been tested. In prosthetic joint replacement a distal venting hole, a large insertion hole and a modified technique for cement insertion have been shown to be valuable methods for pressure reduction. In intramedullary nailing, a distal venting hole, an unreamed nailing technique using solid nails and slow nailing did not alter the pressure increase effectively. Measures such as redimensioning the flexible drive, possibly in combination with special reamer heads, reduction of the insertion force or use of irrigation suction drainage during reaming of the medullary canal represent potential ways preventing this undesirable side effect in this popular internal fixation technique. PMID:7753534

  15. Validation data for photochemical mechanisms: experimental results. Interim report, April 1986-December 1987

    SciTech Connect

    Sexton, K.G.; Arnold, J.R.; Jeffries, H.E.; Kale, T.L.; Kamens, R.M.

    1988-11-01

    The smog-chamber facility of the University of North Carolina (UNC) was used to provide experimental data for the EPA and atmospheric model developers for testing and validating kinetic mechanisms of photochemical smog formation. In the study, 71 dual experiments were performed using NOx and various hydrocarbons and hydrocarbon mixtures. Experiments were also conducted to better understand and characterize (1) the chamber when operated dynamically to simulate continuous emissions and dilution, and (2) the solar radiation inside the smog chamber. The chamber experiments described in the report were added to the existing UNC data base for model testing, bringing the total number of dual experiments in the data base to 417. The data base is available on an ANSI-formatted magnetic tape.

  16. Experimental results in eddy current nondestructive testing based on superconductive and conventional electromagnetic probes

    SciTech Connect

    Valentino, M.; Ruosi, A.; Pepe, G.; Mollo, V.; D`Alto, R.; Peluso, G.

    1999-04-20

    This paper deals with the electromagnetic nondestructive testing performed by SQUID magnetometry on stratified aluminum alloy plates as those commonly encountered in the aircraft industry. The anomalous magnetic fields generated by flaws wit h known electromagnetic characteristics have been modeled by a three-dimensional specific code based on a finite element formulation. The numerical solution has correctly predicted the shape of the complicated magnetic field response due to the defect. Once accuracy and reliability of experimental data taken by superconductive probe have been tested, a benchmark-like problem has been faced. Measurements performed by conventional probes like fluxgate and inductive coil have been compared with the ones taken by innovative device based on superconductive materials.

  17. The experimental results of a self tuning adaptive controller using online frequency identification. [for Galileo spacecraft

    NASA Technical Reports Server (NTRS)

    Chiang, W.-W.; Cannon, R. H., Jr.

    1985-01-01

    A fourth-order laboratory dynamic system featuring very low structural damping and a noncolocated actuator-sensor pair has been used to test a novel real-time adaptive controller, implemented in a minicomputer, which consists of a state estimator, a set of state feedback gains, and a frequency-locked loop for real-time parameter identification. The adaptation algorithm employed can correct controller error and stabilize the system for more than 50 percent variation in the plant's natural frequency, compared with a 10 percent stability margin in frequency variation for a fixed gain controller having the same performance as the nominal plant condition. The very rapid convergence achievable by this adaptive system is demonstrated experimentally, and proven with simple, root-locus methods.

  18. Corrosion by liquid lead and lead-bismuth: experimental results review and analysis

    SciTech Connect

    Zhang, Jinsuo

    2008-01-01

    Liquid metal technologies for liquid lead and lead-bismuth alloy are under wide investigation and development for advanced nuclear energy systems and waste transmutation systems. Material corrosion is one of the main issues studied a lot recently in the development of the liquid metal technology. This study reviews corrosion by liquid lead and lead bismuth, including the corrosion mechanisms, corrosion inhibitor and the formation of the protective oxide layer. The available experimental data are analyzed by using a corrosion model in which the oxidation and scale removal are coupled. Based on the model, long-term behaviors of steels in liquid lead and lead-bismuth are predictable. This report provides information for the selection of structural materials for typical nuclear reactor coolant systems when selecting liquid lead or lead bismuth as heat transfer media.

  19. Investigation of superelastic electron scattering by laser-excited Ba - Experimental procedures and results

    NASA Technical Reports Server (NTRS)

    Register, D. F.; Trajmar, S.; Fineman, M. A.; Poe, R. T.; Csanak, G.; Jensen, S. W.

    1983-01-01

    Differential (in angle) electron scattering experiments on laser-excited Ba-138 1P were carried out at 30- and 100-eV impact energies. The laser light was linearly polarized and located in the scattering plane. The superelastic scattering signal was measured as a function of polarization direction of the laser light with respect to the scattering plane. It was found at low electron scattering angles that the superelastic scattering signal was asymmetric to reflection of the polarization vector with respect to the scattering plane. This is in contradiction with theoretical predictions. An attempt was made to pinpoint the reason for this observation, and a detailed investigation of the influence of experimental conditions on the superelastic scattering was undertaken. No explanation for the asymmetry has as yet been found.

  20. Beta decay and the origin of biologial chirality - New experimental results

    NASA Technical Reports Server (NTRS)

    Van House, J.; Rich, A.; Zitzewitz, P. W.

    1984-01-01

    The hypothetical connection developed by Vester and Ulbricht (1959), between the handedness of beta particles in radioactive decay and the (L) sign of biologial chirality is investigated in a radiolysis experiment. The experiment measured the predicted asymmetry in the formation triplet or 'ortho-' positronium (oPs) in amino acid enantiomers by low energy positrons under conditions of helicity reversal. The positrons were focused on amino acid powder samples. By measuring the time between positron arrival and emission of gamma rays, long-lived oPs were separated from other species. It is found that the asymmetry in leucine (0.8 x 10 to the -4th) is consistent with the theoretical prediction of 10 to the -6th. Neither the experimental limits nor the theoretical estimates are found to rule out a mechanism like that described by Vester and Ulbricht as the cause of the sign of the observed chiral polarization.