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1

Comments on experimental results of energy confinement of tokamak plasmas  

SciTech Connect

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.

Chu, T.K.

1989-04-01

2

Experimental results from CERN on reaction mechanisms in high energy heavy ion collisions  

SciTech Connect

Three main experimental results from CERN concerning reaction mechanisms in high energy heavy ion collisions are discussed: (1) the striking validity of the single particle picture, (2) the nuclear stopping power and (3) the attained energy densities.

Sorensen, S.P. (Oak Ridge National Lab., TN (USA) Tennessee Univ., Knoxville, TN (USA). Dept. of Physics)

1990-01-01

3

Hybrid wind\\/microhydro power system associated with a supercapacitor energy storage device - experimental results  

Microsoft Academic Search

Association of wind power producing units, microhydro power plants and energy storage systems can ensure the stability of an islanded week power grid or can increase the penetration of these renewable energy sources into the large power networks. Experimental results presented in the paper demonstrate the effectiveness of this association. The microhydro power plant consists of a doubly-fed induction generator

Stefan Breban; Mehdi Nasser; Arnaud Vergnol; Benoît Robyns; Mircea M. Radulescu

2008-01-01

4

Modifications of the high-energy transport code (HETC) and comparisons with experimental results  

SciTech Connect

The High-Energy Transport Code HETC has been revised by incorporating a multi-chain fragmentation model to describe particle production from high-energy hadron-nucleus collisions. The revised code is briefly described and its validity is tested by comparing calculated results with experimental data from 29.4 GeV protons incident on an iron-air beam stop and with experimental data from 800 GeV protons incident on a large iron block. Some comparisons with calculated results obtained with other available transport codes; FLUKA82, CASIM, and MARS10 are also included. 18 refs., 3 figs.

Alsmiller, R.G. Jr.; Alsmiller, F.S.; Gabriel, T.A.; Hermann, O.W.

1987-01-01

5

Advanced energy-efficient house (HARBEMAN house) with solar thermal, photovoltaic, and sky radiation energies (experimental results)  

Microsoft Academic Search

An energy-independent residential house (‘HARBEMAN house’; Harmony BEtween Man And Nature), incorporating sky radiation cooling, solar thermal, and photovoltaic energies was built in Sendai, Japan during July, 1996. This paper reports monitored results of this house since September 1996 to date. The paper also presents simulation results for the HARBEMAN house and its results compared with the annual experimental data.

Takeo S. Saitoh; Tetsuji Fujino

2001-01-01

6

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

7

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

NASA Technical Reports Server (NTRS)

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.

Jacqmin, David

1995-01-01

8

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

NASA Technical Reports Server (NTRS)

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.

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

1975-01-01

9

Variable Entry Biased Paracentric Hemispherical Deflector: Experimental results on energy resolution for different entry positions  

NASA Astrophysics Data System (ADS)

A new hemispherical deflector analyzer (HDA) which is designed for electron energy analysis in atomic collisions has been constructed and tested. Using the crossed beam technique at the electron spectrometer, test measurements were performed for electron beam (200 eV) – Helium atoms interactions. These first experimental results show that the paracentric entries give almost twice as good resolution as that for the conventional entry. Supporting simulations of the entire lens+HDA spectrometer are found in relatively good agreement with experiment.

Dogan, Mevlut; Ulu, Melike; Gennerakis, Giannis; Zouros, Theo J. M.

2014-04-01

10

Experimental Results from the Thermal Energy Storage-1 (TES-1) Flight Experiment  

NASA Technical Reports Server (NTRS)

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).

Wald, Lawrence W.; Tolbert, Carol; Jacqmin, David

1995-01-01

11

Experimental results from the Thermal Energy Storage-1 (TES-1) flight experiment  

NASA Astrophysics Data System (ADS)

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).

Wald, Lawrence W.; Tolbert, Carol; Jacqmin, David

1995-09-01

12

Experimental Results from the Thermal Energy Storage-2 (TES-2) Flight Experiment  

NASA Technical Reports Server (NTRS)

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 Energy Storage Simulation (TESSIM) analytical computer code. An analysis of the TES-2 data was conducted by Cleveland State University Professor, Mounir Ibrahim. TESSIM validation was based on two types of results; temperature history of various points on the containment vessel and TES material distribution within the vessel upon return from flight. The TESSIM prediction showed close comparison with the flight data. Distribution of the TES material within the vessel was obtained by a tomography imaging process. The frozen TES material was concentrated toward the colder end of the canister. The TESSIM prediction indicated a similar pattern. With agreement between TESSIM and the flight data, a computerized representation was produced to show the movement and behavior of the void during the entire melting and freezing cycles.

Tolbert, Carol

2000-01-01

13

Experimental Results from RO-PRO: A Next Generation System for Low-Energy Desalination.  

PubMed

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/m(2). This is higher than previous river-to-sea PRO pilot systems (1.5 W/m(2)) and closer to the goal of 5 W/m(2) 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/m(2) 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/m(3). PMID:24798068

Achilli, Andrea; Prante, Jeri L; Hancock, Nathan T; Maxwell, Eric B; Childress, Amy E

2014-06-01

14

Theoretical predictions of experimental observables sensitive to the symmetry energy. Results of the SMF transport model  

NASA Astrophysics Data System (ADS)

In the framework of mean-field-based transport approaches, we discuss recent results concerning heavy-ion reactions between charge asymmetric systems, from low up to intermediate energies. We focus on isospin sensitive observables, aiming at extracting information on the density dependence of the isovector part of the nuclear effective interaction and of the nuclear symmetry energy. For reactions close to the Coulomb barrier, we explore the structure of collective dipole oscillations, rather sensitive to the low-density behavior of the symmetry energy. In the Fermi energy regime, we investigate the interplay between dissipation mechanisms, fragmentation and isospin effects. At intermediate energies, where regions with higher density and momentum are reached, we discuss collective flows and their sensitivity to the momentum dependence of the isovector interaction channel, which determines the splitting of neutron and proton effective masses. Finally, we also discuss the isospin effect on the possible phase transition from nucleonic matter to quark matter. Results are critically reviewed, also trying to establish a link, when possible, with the outcome of other transport models.

Colonna, Maria; Baran, Virgil; Di Toro, Massimo

2014-02-01

15

Frictional cooling: Experimental results  

NASA Astrophysics Data System (ADS)

The classical methods used in beam cooling are hard to be adapted for a beam of short-lived elementary particles. A novel method, the so-called frictional cooling - that is cooling a beam of low-energy charged particles by moderation in matter and acceleration in an electrostatic field - has been shown to be feasible. In our experiments performed in 1994/1995 a beam of short-lived particles was cooled for the first time ever. Utilizing frictional cooling on a beam of slow negative muons we observed increase in phase space density by about one order of magnitude.

Mühlbauer, M.; Daniel, H.; Hartmann, F. J.; Hauser, P.; Kottmann, F.; Petitjean, C.; Schott, W.; Taqqu, D.; Wojciechowski, P.

1999-06-01

16

PDX experimental results  

SciTech Connect

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.

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

1981-01-01

17

Relativistic klystron experimental results  

SciTech Connect

Relativistic klystrons are being developed as a power source for high-gradient accelerator applications which include compact accelerators, large linear electron-positron colliders, and FEL sources. We have attained 200 MW peak power at 11.4 GHz from a relativistic klystron, and 140 MV longitudinal gradient in a short 1.4-GHz accelerator section. We report here on the design of our first klystrons, the results of our experiments so far, and some of our plans for the near future. 4 refs., 1 fig., 1 tab.

Westenskow, G.A.

1988-10-27

18

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

National Technical Information Service (NTIS)

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 nev...

D. Jacqmin

1995-01-01

19

Experimental Determination of the Energy Released as a Result of Neutron Capture by Gadolinium  

Microsoft Academic Search

A method for performing direct measurements of the energy of the neutron-capture reaction on gadolinium is proposed and tested. Measurement of the absorbed dose is an important problem for gadolinium neutron-capture therapy.

S. A. Klykov; S. P. Kapchigashev; V. I. Potetnya; S. E. Ul'yanenko; E. S. Matusevich; Yu. A. Kurachenko

2001-01-01

20

The ionization energies of polychlorinated dibenzo- p-dioxins: new experimental results and theoretical studies  

Microsoft Academic Search

In this work we examine the effect of successive introductions of chlorine substituents on the ionization energy (IE) of dibenzo-p-dioxin. The ionization energies of dibenzo-p-dioxin (7.598 ± 0.002 eV) and 2-monochlorodibenzo-p-dioxin (7.707 ±0.002 eV) are obtained using the method of resonance-enhanced two-color two-photon ionization (REMPI) in a cold molecular jet combined with time-of-flight (TOF) mass spectrometry. They are compared with

R. Zimmermann; U. Boesl; D. Lenoir; A. Kettrup; Th. L. Grebner; H. J. Neusser

1995-01-01

21

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

National Technical Information Service (NTIS)

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...

L. W. Wald C. Tolbert D. Jacqmin

1995-01-01

22

Experimental Test Results of Energy Efficient Transport (EET) High-Lift Airfoil in Langley Low-Turbulence Pressure Tunnel  

NASA Technical Reports Server (NTRS)

This report describes the results of an experimental study conducted in the Langley Low-Turbulence Pressure Tunnel to determine the effects of Reynolds number and Mach number on the two-dimensional aerodynamic performance of the Langley Energy Efficient Transport (EET) High-Lift Airfoil. The high-lift airfoil was a supercritical-type airfoil with a thickness-to- chord ratio of 0.12 and was equipped with a leading-edge slat and a double-slotted trailing-edge flap. The leading-edge slat could be deflected -30 deg, -40 deg, -50 deg, and -60 deg, and the trailing-edge flaps could be deflected to 15 deg, 30 deg, 45 deg, and 60 deg. The gaps and overlaps for the slat and flaps were fixed at each deflection resulting in 16 different configurations. All 16 configurations were tested through a Reynolds number range of 2.5 to 18 million at a Mach number of 0.20. Selected configurations were also tested through a Mach number range of 0.10 to 0.35. The plotted and tabulated force, moment, and pressure data are available on the CD-ROM supplement L-18221.

Morgan, Harry L., Jr.

2002-01-01

23

Recent Experimental Results from MRX  

NASA Astrophysics Data System (ADS)

MRX (Magnetic Reconnection Experiment) is dedicated to studying the fundamental physics of magnetic reconnection. Here, we present results from a new operational mode, ``push mode''(M. Yamada et al., Phys. Plasmas 4), 1936 (1997). (private flux reconnected into common flux), in which counter-helicity (opposite B_T) and co-helicity (same B_T) reconnection can be studied. Results previously reported were predominantly from ``pull mode''^1 (common flux reconnected into private flux) and null-helicity (no B_T) experiments. Physics topics which can be addressed advantageously in the push mode include: (1) conversion of magnetic energy to plasma kinetic and thermal energy, (2) effects of boundary conditions on reconnection rate, and (3) helicity dissipation in the reconnection layer. Measurements of B are taken with arrays of small pickup coils. Plasma parameters n_e, T_e, T_i, and ion flow VD are taken with Langmuir probes and a retarding-field gridded energy analyzer (RGEA). These data are supplemented with multi-chord measurements of HeII (4686 Åline emission, on which Abel inversion will be performed. Results to date indicate that direct ion heating occurs during reconnection (T_i>Te and ?_eq,ei >> ?_rec) and near the reconnection layer and that ion current is a significant fraction of the total reconnection current sheet. Implications for all three physics topics above will be discussed.

Hsu, S.; Himura, H.; Carter, T.; Zaharia, S.; Ji, H.; Yamada, M.; Brown, M.

1998-11-01

24

P2G-4 Suppression of Acoustic Energy Leakage in FBARs with Al Bottom Electrode: FEM Simulation and Experimental Results  

Microsoft Academic Search

One of the most challenging issues in designing film bulk acoustic wave resonators (FBARs) is how to realize high-Q resonators. According to our experimental results, an acoustic leakage is the dominant loss factor at antiresonance frequency for FBARs with an aluminum bottom electrode. In this paper, we report simulation results obtained using the 2-dimensional finite element method (2D FEM), which

Ryoichi Ohara; Naoko Yanase; Takaaki Yasumoto; Minoru Kawase; Shingo Masuko; Tetsuya Ohno; K. Sano

2007-01-01

25

Thermal experimental results on the prototype for high power neutron converter for low energy proton/deuteron beams  

NASA Astrophysics Data System (ADS)

In the framework of the European program aimed at the developing of a second generation radioactive ion beam (RIB) facility, the Legnaro National Laboratories (LNL) propose in the next few years the construction of a specialized national facility for RIB originated by fission fragments produced by fast neutrons (SPES). Protons/deuterons of 40 MeV (150 kW) will produce about 10 14 neutrons per second in a converter with energy centered at around 14 MeV which will induce fission in a suitable fissile target, with the aim of 10 13 fissions per second at least. A rotating target includes the converter made of 13C-based material or natural carbon (for proton and deuteron beams, respectively), and cooled mainly by thermal radiation. This paper presents the design of the prototype, as well as the thermal experimental results with high-power electron beams. The prototype comprises the carbon-made neutron converter mounted on the rotating metal disk of 30 cm in diameter and designed to dissipate 50 kW of beam power at nominal operation condition. The test consists of the prototype converter irradiation with the high-power electron beam (beam size below 1 cm) of the ELV-6 accelerator. The prototype successfully remained under nominal conditions. In addition, the prototype was submitted to a beam power of 70 kW, which exceeds of 40% the design power, without any appreciable damage on the converter material. The results are in good agreement with the numerical simulations.

Alyakrinskiy, O.; Antoshin, A.; Avilov, M.; Bolkhovityanov, D.; Fadeev, S.; Golikov, V.; Gubin, K.; Lebedev, N.; Logatchev, P.; Popov, V.; Shiyankov, S.; Tecchio, L. B.

2007-08-01

26

Dielectric energy of orientation in dead and living cells of Schizosaccharomyces pombe. Fitting of experimental results to a theoretical model.  

PubMed Central

Using the experimental data obtained with killed cells of Schizosaccharomyces pombe (1), we have formulated a theoretical model that is able to predict cell orientation for microorganisms with ellipsoidal or cylindrical shapes as a function of the frequency of the electric field and of the conductivity of the external medium. In this model, comparison of the difference in potential energy for both orientations parallel-perpendicular with the thermal agitation energy allows one to interpret the intervals where these orientations occur. The model implies that the conductivity of the cytoplasm is slightly higher than that of the external medium. This assumption is easy to understand taking into account that not all the intracytoplasmic material is released to the exterior during cell death.

Asencor, F J; Santamaria, C; Iglesias, F J; Dominguez, A

1993-01-01

27

Majorana Thermosyphon Prototype Experimental Results  

SciTech Connect

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.

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

2010-12-17

28

Experimental study and computer simulations of the energy loss straggling of slow ions in thin foils: Results for H+ and D+ in C, Si, Cu, Ag and Bi  

NASA Astrophysics Data System (ADS)

We present an experimental and computer simulation study of the energy loss straggling of low energy (2-10 keV) proton and deuteron beams in C, Si, Cu, Ag and Bi. The measurements were done using the transmission technique with several self-supporting foils with thicknesses in the range of 13-25 nm. The computer simulations were based on a Monte Carlo code which provides a method to analyze in detail the influence of various effects, such as foil roughness and slowing down of the ions in the medium. The theoretical model for the stopping and straggling coefficients is based on the Density Functional Theory. The results of the simulations yield a good agreement with the experimental values for the total straggling, taking into account the target roughness which significantly increases the measured energy widths. Within the experimental uncertainties the results show a linear dependence of the energy loss straggling with the projectile velocity and no isotopic effects. The results clearly indicate that a quantitative analysis of the energy loss straggling in this energy range requires a careful evaluation of the foil roughness effect.

Celedón, C. E.; Cantero, E. D.; Lantschner, G. H.; Arista, N. R.

2013-11-01

29

Cleanroom energy benchmarking results  

SciTech Connect

A utility market transformation project studied energy use and identified energy efficiency opportunities in cleanroom HVAC design and operation for fourteen cleanrooms. This paper presents the results of this work and relevant observations. Cleanroom owners and operators know that cleanrooms are energy intensive but have little information to compare their cleanroom's performance over time, or to others. Direct comparison of energy performance by traditional means, such as watts/ft{sup 2}, is not a good indicator with the wide range of industrial processes and cleanliness levels occurring in cleanrooms. In this project, metrics allow direct comparison of the efficiency of HVAC systems and components. Energy and flow measurements were taken to determine actual HVAC system energy efficiency. The results confirm a wide variation in operating efficiency and they identify other non-energy operating problems. Improvement opportunities were identified at each of the benchmarked facilities. Analysis of the best performing systems and components is summarized, as are areas for additional investigation.

Tschudi, William; Xu, Tengfang

2001-09-01

30

Mach's Principle and Propulsion: Experimental Results  

Microsoft Academic Search

Mass fluctuations that arise from Mach effects when objects that can store internal energy are accelerated and their application to the production of propellantless thrusts are briefly reviewed. Follow-on experimental work to that reported at STAIF 2004, 2005, and 2006 is described. In particular, thrusts in ``flux capacitors'' made with high voltage disk capacitors wound with coils that produce a

James F. Woodward

2007-01-01

31

PAVAD B Design and Experimental Results Report.  

National Technical Information Service (NTIS)

The application and experimental results are presented for the Passive and Advanced Vibro-Acoustic Treatments Demonstration, Part B (PAVAD-B) conducted at the Laboratory for Structural Acoustics, Naval Research Laboratory (NRL) during the winter and sprin...

C. Herdic B. H. Houston R. D. Corsaro

2006-01-01

32

Results from an experimental railgun system: ERGS-1A  

Microsoft Academic Search

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

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

1983-01-01

33

Bioreactor landfills: experimental and field results  

Microsoft Academic Search

Bioreactor landfills allow a more active landfill management that recognizes the biological, chemical and physical processes involved in a landfill environment. This paper presents the results of an experimental study carried out to determine the effect of solid waste size, leachate recirculation and nutrient balance on the rate of municipal solid waste (MSW) biodegradation. Higher rates of MSW biodegradation eventually

Mostafa Warith

2002-01-01

34

Synthesis of H2 in dirty ice mantles by fast ion energy loss: New experimental results increase the relevance of this mechanism  

NASA Technical Reports Server (NTRS)

Recent experimental results support the importance of H2 production in molecular clouds by cosmic ray bombardment of the mantles of grains. The formation of molecules different from those originally present in the irradiated layer can be explained by the production of molecular fragments induced by the release of energy if the impinging fast particle. One way of considering the process is in terms of a transiently hot cylinder, initially about 50 A in diameter, that exists around the track of an individual fast ion. Since ice has a relatively low thermal conductivity, energy lost by the ion in the ice layers remains confined around the track for time long enough to be thermalized. The hot cylinder increases in diameter and decreases in temperature on a time scale of 10(exp -11) to 10(exp -10) sec. Molecular fragments that are formed in this high temperature region acquire enough mobility to recombine with different partners, forming new molecules. A Monte Carlo simulation of the interaction between cosmic rays and grain mantles, at various depths in the core of a spherical molecular cloud, was performed. The simulation was continued until 40,000 ions had hit each grain of the type and size chosen. During the performed experiments thin icy films made of H2O and CD4 mixed in the gas phase and deposited on a cold finger at 9 K were irradiated with 1.5 MeV helium beams. Among synthesized molecules were found H2, HD, and D2.

Pirranello, Valero; Brown, W. L.; Lanzerotti, L. J.; Averna, D. A.

1989-01-01

35

Microwave radiometry for humanitarian demining: experimental results  

NASA Astrophysics Data System (ADS)

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.

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

2002-08-01

36

Experimental SGEMP results using electron beam injection  

Microsoft Academic Search

This paper presents results from a SGEMP\\/IEMP phenomenological experiment designed to explore the behavior of an axially injected electron beam within a cylindrical test chamber. Data on two different injected beams characterized by mean electron energies of 40 and 60 keV and pulse durations of approximately 80 and 30 nsecs full width at half maximum (FWHM) respectively are presented. These

R. J. Fisher; J. S. Duval; W. F. Rich

1975-01-01

37

Experimental SGEMP Results Using Electron Beam Injection  

Microsoft Academic Search

This paper presents results from a SGEMP\\/IEMP phenomenological experiment designed to explore the behavior of an axially injected electron beam Within a cylindrical test chamber, Data on two different injected beams characterized by mean electron energies of 40 and 60 keV and pulse durations of approximately 80 and 30 nsecs full width at half maximum (FWHM) respectively are presented. These

Richard J. Fisher; Joseph S. Duval; W. Foster Rich

1975-01-01

38

Fuel-rich, catalytic reaction experimental results  

NASA Technical Reports Server (NTRS)

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.

Rollbuhler, R. James

1991-01-01

39

Propellantless propulsion: Recent experimental results exploiting transient mass modification  

Microsoft Academic Search

An assortment of papers have been published over the years setting forth theory suggesting inertia stems from the gravitational effects of the totality of matter in the universe (Mach's Principle). This has been supported by positive results of experimental attempts by Woodward to transiently modify the inertia of test masses. By rapidly oscillating the energy density of the test masses

Thomas L. Mahood

1999-01-01

40

Overview of the initial NSTX experimental results  

SciTech Connect

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 = 1:6{2.2 and triangularity = 0:2{0.4, were achieved in inner wall limited, and single null and double null diverted congurations. 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 , T , 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 T 18% at a plasma current of 1.1 MA.

Ono, M. [Princeton Plasma Physics Laboratory (PPPL); Peng, Yueng Kay Martin [ORNL

2000-01-01

41

Overview of the Initial NSTX Experimental Results  

SciTech Connect

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

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

2000-11-16

42

Overview of the Initial NSTX Experimental Results  

SciTech Connect

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 central density 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 operation 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 plasm current of 1.1 MA.

Ono, M. [Princeton Plasma Physics Laboratory (PPPL); Bell, M. [Princeton Plasma Physics Laboratory (PPPL); Bell, R. E. [Princeton Plasma Physics Laboratory (PPPL); Bigelow, Tim S [ORNL; Bitter, M. [Princeton Plasma Physics Laboratory (PPPL); Blanchard, W. [Princeton Plasma Physics Laboratory (PPPL); Darrow, D. [Princeton Plasma Physics Laboratory (PPPL); Fredrickson, E. [Princeton Plasma Physics Laboratory (PPPL); Gates, D. [Princeton Plasma Physics Laboratory (PPPL); Grisham, L. [Princeton Plasma Physics Laboratory (PPPL); Hosea, J. [Princeton Plasma Physics Laboratory (PPPL); Kaye, S. [Princeton Plasma Physics Laboratory (PPPL); Kaita, R. [Princeton Plasma Physics Laboratory (PPPL); Kubota, S. [University of California, Los Angeles; Kugel, H. [Princeton Plasma Physics Laboratory (PPPL); Johnson, D. [Princeton Plasma Physics Laboratory (PPPL); LeBlanc, B [Princeton Plasma Physics Laboratory (PPPL); Maingi, Rajesh [ORNL; Maqueda, R. [Los Alamos National Laboratory (LANL); Mazzucato, E. [Princeton Plasma Physics Laboratory (PPPL); Menard, J. [Princeton Plasma Physics Laboratory (PPPL); Mueller, D. [Princeton Plasma Physics Laboratory (PPPL); Nelson, Brad E [ORNL; Neumeyer, C. L. [Princeton Plasma Physics Laboratory (PPPL); Paoletti, F. [Columbia University; Paul, S. [Princeton Plasma Physics Laboratory (PPPL); Peng, Yueng Kay Martin [ORNL; Ramakrishnan, S. [Princeton Plasma Physics Laboratory (PPPL); Raman, R. [University of Washington, Seattle; Ryan, Philip Michael [ORNL; Sabbagh, S. A. [Columbia University; Skinner, C. [Princeton Plasma Physics Laboratory (PPPL); Stevenson, T. [Princeton Plasma Physics Laboratory (PPPL); Stutman, D. [Johns Hopkins University; Synakowski, E. J. [Princeton Plasma Physics Laboratory (PPPL); Swain, David W [ORNL; Taylor, G. [Princeton Plasma Physics Laboratory (PPPL); Von Halle, A. [Princeton Plasma Physics Laboratory (PPPL); Wilgen, John B [ORNL; Williams, M. [Princeton Plasma Physics Laboratory (PPPL); Wilson, J. R. [Princeton Plasma Physics Laboratory (PPPL); Ackers, R. [EURATOM / UKAEA, UK; Barry, Robert E [ORNL; Bers, A. [Massachusetts Institute of Technology (MIT); Bialek, J. [Columbia University; Bonoli, P. [Massachusetts Institute of Technology (MIT); Carter, Mark Dwain [ORNL; Chrzanowski, J. [Princeton Plasma Physics Laboratory (PPPL); Davis, W. [Princeton Plasma Physics Laboratory (PPPL); Doyle, E. J. [University of California, Los Angeles; Dudek, L. [Princeton Plasma Physics Laboratory (PPPL); Ellis, R. [Princeton Plasma Physics Laboratory (PPPL); Efthimion, P. C. [Princeton Plasma Physics Laboratory (PPPL); Ferron, J. R. [General Atomics; Fredd, E. [Princeton Plasma Physics Laboratory (PPPL); Finkenthal, M. [Johns Hopkins University; Gibney, T. [Princeton Plasma Physics Laboratory (PPPL); Goldston, R. [Princeton Plasma Physics Laboratory (PPPL); Hatcher, R. E. [Princeton Plasma Physics Laboratory (PPPL); Hawryluck, R. [Princeton Plasma Physics Laboratory (PPPL); Hayashiya, H. [Fusion Physics and Technology; Hill, K. [Princeton Plasma Physics Laboratory (PPPL); Jarboe, T. [University of Washington, Seattle; Jardin, S. C. [Princeton Plasma Physics Laboratory (PPPL); Ji, H. [Princeton Plasma Physics Laboratory (PPPL); Kalish, M. [Princeton Plasma Physics Laboratory (PPPL); Lao, L. L. [General Atomics; Lee, K. C. [University of California, Davis; Levinton, F. [Fusion Physics and Technology; Luhmann, N. C. [University of California, Davis; Lamarche, P. [Princeton Plasma Physics Laboratory (PPPL); McCormack, B. [Princeton Plasma Physics Laboratory (PPPL); Majeski, R. [Princeton Plasma Physics Laboratory (PPPL); Manickam, J. [Princeton Plasma Physics Laboratory (PPPL); Marsala, R. [Princeton Plasma Physics Laboratory (PPPL); Mau, T. K. [University of California, San Diego; Medley, S. [Princeton Plasma Physics Laboratory (PPPL); et al.

2001-01-01

43

A new method for the determination of the specific kinetic energy (SKE) released to pyroclastic particles at magmatic fragmentation: theory and first experimental results  

NASA Astrophysics Data System (ADS)

Brittle magmatic fragmentation plays a crucial role in explosive eruptions. It represents the starting point of hazardous explosive events that can affect large areas surrounding erupting volcanoes. Knowing the initial energy released during this fragmentation process is fundamental for the understanding of the subsequent dynamics of the eruptive gas-particle mixture and consequently for the forecasting of the erupting column's behavior. The specific kinetic energy (SKE) of the particles quantifies the initial velocity shortly after the fragmentation and is therefore a necessary variable to model the gas-particle conduit flow and eruptive column regime. In this paper, we present a new method for its determination based on fragmentation experiments and identification of the timings of energy release. The results obtained on compositions representative for basaltic and phonolitic melts show a direct dependence on magma material properties: poorly vesiculated basaltic melts from Stromboli show the highest SKE values ranging from 7.3 to 11.8 kJ/kg, while experiments with highly vesiculated samples from Stromboli and Vesuvius result in lower SKE values (3.1 to 3.8 kJ/kg). The described methodology presents a useful tool for quantitative estimation of the kinetic energy release of magmatic fragmentation processes, which can contribute to the improvement of hazard assessment.

Dürig, Tobias; Dioguardi, Fabio; Büttner, Ralf; Dellino, Pierfrancesco; Mele, Daniela; Zimanowski, Bernd

2012-05-01

44

Experimental results on single flux quantum logic  

Microsoft Academic Search

The authors have optimized the design and calculated the margins for a number of single flux quantum (SFQ) logic elements, including AND, OR, XOR, splitter, DC-to-SFQ converter, and SFQ-to-DC converter. These are the fundamental building blocks necessary to construct more complex logic functions such as the half adder and full adder. Experimental tests of the primary gates, the AND, OR,

S. P. Benz; C. J. Burroughs; C. A. Hamilton

1993-01-01

45

Model Comparisons with STELLA Experimental Results  

SciTech Connect

High-trapping efficiency and narrow energy spread in a staged laser acceleration system was demonstrated during the Staged Electron Laser Acceleration (STELLA) experiment. The experiment used inverse free electron lasers (IFEL) driven by the Brookhaven National Laboratory Accelerator Test Facility (ATF) CO2 laser. The First IFEL modulated the electron beam energy. A subsequent chicane created a train of {approx}3 fs-long microbunches separated by 10.6 {mu}m. These microbunches are trapped and accelerated in a second IFEL, where up to 80% trapping efficiencies and energy spreads down to 0.36% (1{sigma}) were measured. This paper presents additional model comparisons with the data, and discusses the strengths and limitations of the model.

Kimura, W.D.; Campbell, L.C.; Dilley, C.E.; Gottschalk, S.C.; Quimby, D.C. [STI Optronics, Inc., 2755 Northup Way, Bellevue, WA 98004 (United States); Babzien, M.; Ben-Zvi, I.; Gallardo, J.C.; Pogorelsky, I.V.; Skaritka, J.; Yakimenko, V. [Brookhaven National Laboratory, Upton, NY 11973 (United States); Cline, D.B.; Zhou, F. [University of California, Los Angeles, Los Angeles, CA 90095 (United States); Kusche, K.P. [STI Optronics, Inc., 2755 Northup Way, Bellevue, WA 98004 (United States); Brookhaven National Laboratory, Upton, NY 11973 (United States); Pantell, R.H. [Stanford University, Stanford, CA 94305 (United States); Steinhauer, L.C. [University of Washington, Redmond Plasma Physics Laboratory, Redmond, WA 98052 (United States)

2004-12-07

46

Testing Numerical Dynamo Models Against Experimental Results  

NASA Astrophysics Data System (ADS)

Significant progress has been achieved over the past few years in describing the geomagnetic field using computer models for dynamo action. Such models are so far limited to parameter regimes which are very remote from actual values relevant to the Earth core or any liquid metal (the magnetic Prandtl number is always over estimated by a factor at least 104). While existing models successfully reproduce many of the magnetic observations, it is difficult to assert their validity. The recent success of an experimental homogeneous unconstrained dynamo (VKS) provides a new way to investigate dynamo action in turbulent conducting flows, but it also offers a chance to test the validity of exisiting numerical models. We use a code originaly written for the Geodynamo (Parody) and apply it to the experimental configuration. The direct comparison of simulations and experiments is of great interest to test the predictive value of numerical simulations for dynamo action. These turbulent simulations allow us to approach issues which are very relevant for geophysical dynamos, especially the competition between different magnetic modes and the dynamics of reversals.

Gissinger, C. J.; Fauve, S.; Dormy, E.

2007-12-01

47

Experimental rotordynamic coefficient results for honeycomb seals  

NASA Technical Reports Server (NTRS)

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.

Elrod, David A.; Childs, Dara W.

1988-01-01

48

TRU Waste Certification: Experimental Data and Results.  

National Technical Information Service (NTIS)

As part of the TRU waste certification program at Mound, experiments were performed, and the results were used to verify certification of various TRU wastes with regard to specific WIPP (Waste Isolation Pilot Plant) criteria. Particle-size determinations ...

E. L. Lewis

1983-01-01

49

Adaptive structures - Test hardware and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1990-01-01

50

The Humanoid Robot LOLA-Experimental Results  

NASA Astrophysics Data System (ADS)

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.

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

2010-09-01

51

Experimental Results of the Coaxial Multipactor Experiment (CMX)  

SciTech Connect

A multipactor discharge is a resonant condition for electrons in an alternating electric field. This discharge can be disruptive to RF circuits, cavities, and resonators by detuning the circuit and/or by seeding an arc with a partially developed multipactor discharge. The Coaxial Multipactor Experiment (CMX) investigates this discharge with goals of measuring the electron distribution, current, and absorbed power from the non-uniform RF field in coaxial transmission lines. CMX has a unique experimental setup which can support a multipactor discharge in a short section of continuous transmission line. A retarding potential analyzer with secondary electron suppression measures the multipactor electron distribution. Results depict a narrow, relatively high-energy distribution of electrons which exhibits energy dependence on frequency and not pressure below 1 mtorr. Each distribution has an energetic tail which extends to the maximum RF cavity voltage. Monte Carlo simulations reproduce the measured distributions and show dependence on the initial electron energy and phase distributions.

Graves, Timothy P.; LaBombard, B.; Wukitch, S.J.; Hutchinson, I.H. [MIT-PSFC, Cambridge, MA 02139 (United States)

2005-09-26

52

Recent double beta decay experimental results  

SciTech Connect

Double beta decay experiments continue to contribute illuminating and constraining factors in the fields of nuclear and particle physics. Recently, there have been a number of half-life measurements realized for two-neutrino double beta decay candidates, often with data samples of high statistical significance. Searches for neutrinoless double beta decay and for new Majoron emitting decay modes have resulted in half-life limits only. For the zero-neutrino mode, these limits have pushed the Majorana neutrino mass to less than 1 eV. Currently, the generation of small source mass experiments is coming to an end. In the spirit of the {sup 76}Ge experiments, promising next generation research will need to study several kilograms of ultra-pure, isotopically-enriched double beta decay sources.

Sutton, C. Sean [Physics Department, Mount Holyoke College, South Hadley, Massachusetts 01075 (United States)

1997-05-20

53

ACCELERATORS: Experimental results of helicon sources  

NASA Astrophysics Data System (ADS)

Helicon plasma sources are known as efficient generators of uniform and high density plasma. A helicon plasma source was developed for the investigation of plasma stripping and plasma lenses at the Institute of Modern Physics, CAS. In this paper, the characteristics of helicon plasma have been studied by using a Langmuir four-probe and a high plasma density up to 3.9 × 1013/cm3 has been achieved with the Nagoya type III antenna. In the experiment, several important phenomena were found: (1) for a given magnetic induction intensity, the plasma density became greater with the increase of RF power; (2) helicon mode appeared at RF power between 300 W and 400 W; (3) the plasma density gradually tended to saturation as the RF power increased to the higher power; (4) a higher plasma density can be obtained by a good match between the RF power and the magnetic field distribution. The key issue is how to optimize the matching between the RF power and the magnetic field. Moreover, some tests on the extraction of ion beams were performed, and preliminary results are given. The problems which existed in the helicon ion source will be discussed and the increase in beam density will be expected by extraction system optimum.

Miao, Ting-Ting; Shang, Yong; Liu, Zhan-Wen; Zhao, Hong-Wei; Sun, Liang-Ting; Zhang, Xue-Zhen; Zhao, Huan-Yu; Wang, Hui; Ma, Bao-Hua; Li, Xi-Xia; Zhu, Yu-Hua; Feng, Yu-Cheng; Lijing-Yu

2009-10-01

54

Experimental results from the TFTR tokamak  

SciTech Connect

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.

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

55

Propellantless propulsion: Recent experimental results exploiting transient mass modification  

NASA Astrophysics Data System (ADS)

An assortment of papers have been published over the years setting forth theory suggesting inertia stems from the gravitational effects of the totality of matter in the universe (Mach's Principle). This has been supported by positive results of experimental attempts by Woodward to transiently modify the inertia of test masses. By rapidly oscillating the energy density of the test masses (i.e., charging and discharging high-energy capacitors), apparent transient mass shifts of up to +/-10% of the active dielectric material were consistently obtained. It became apparent that such an effect, when coupled with precisely timed external impulsive forces, could result in a net force, that is, propulsion without the expulsion of a reactive propellant, utilizing only electricity as ``fuel.'' Several generations of devices have been constructed and tested supporting this concept of propulsion.

Mahood, Thomas L.

1999-01-01

56

Experimental results on quantum chromo dynamics: what is next?  

NASA Astrophysics Data System (ADS)

This review gives a flavour of experimental quantum chromo dynamics (QCD) results obtained at the Large Hadron Collider (LHC) during the first run period in the years 2010-2012. The results cover selected aspects of soft low-pT phenomena, typically described by phenomenological models, as well as high-pT processes which can be studied theoretically with perturbative techniques. In general the phenomenological models required tuning to describe the data in the new energy region of 7-8 TeV, while perturbative QCD (pQCD) is found to work generally quite well for most of the phase space currently studied. The strong force will remain a main topic of research at colliders such as the LHC also in future, with the large data samples allowing for more detailed studies and in particular when the next energy level of 13-14 TeV will be reached.

De Roeck, Albert

2013-12-01

57

New experimental results on the antikaon nucleon interaction  

NASA Astrophysics Data System (ADS)

The antikaon interaction on nucleons and nuclei in the low-energy regime is a challenging research field in experiment and theory. Now new precise data are available from x-ray spectroscopy of simple hadronic atoms with strangeness like kaonic hydrogen and helium isotopes. A solid basis is given to extract precision data on the strong interaction observables. The precision measurement of the hadronic shift and width by SIDDHARTA at DAFNE/Frascati lead to the up-to-now most precise values. Therefore, SIDDHARTA is a key experiment for the understanding of low-energy QCD with strangeness. The SIDDHARTA experimental method, the final results and the implications as well as future opportunities will be presented.

Marton, Johann

2012-03-01

58

Numerical simulation of electromagnetic coupling and comparison with experimental results  

Microsoft Academic Search

A comparison between simulations using transmission line modeling (TLM) and experimental results is presented, with particular regard to problems in electromagnetic compatibility (EMC). Procedures for improved measurements and simulations inside a screened-room environment are discussed. Excellent agreement with the experimental results is found for simulations made using a variable mesh TLM technique

Alistair P. Duffy; Phillip Naylor; Trevor M. Benson; Christos Christopoulos

1993-01-01

59

Experimental High Energy Neutrino Astrophysics  

SciTech Connect

Neutrinos are considered promising probes for high energy astrophysics. More than four decades after deep water Cerenkov technique was proposed to detect high energy neutrinos. Two detectors of this type are successfully taking data: BAIKAL and AMANDA. They have demonstrated the feasibility of the high energy neutrino detection and have set first constraints on TeV neutrino production astrophysical models. The quest for the construction of km3 size detectors have already started: in the South Pole, the IceCube neutrino telescope is under construction; the ANTARES, NEMO and NESTOR Collaborations are working towards the installation of a neutrino telescope in the Mediterranean Sea.

Distefano, Carla [Laboratori Nazionali del Sud, Catania (Italy)

2005-10-12

60

Mach’s Principle and Propulsion: Experimental Results  

Microsoft Academic Search

Mass fluctuations that arise from Mach effects when objects that can store internal energy are accelerated and their application to the production of propellantless thrusts are briefly reviewed. Follow-on experimental work to that reported at STAIF 2004, 2005, and 2006 is described. In particular, thrusts in “flux capacitors” made with high voltage disk capacitors wound with coils that produce a

James F. Woodward

2007-01-01

61

Dark matter or neutrino recoil? Interpretation of recent experimental results  

NASA Astrophysics Data System (ADS)

The elastic nuclear recoil signal, being under intense scrutiny by multiple underground experiments, can be interpreted either as coming from the interaction of nuclei with WIMP dark matter or from the scattering of new species of MeV-energy neutrinos. The most promising model for the latter case is a neutrino ?b that interacts with baryon number and with a flux sourced by the oscillations of regular solar B8 neutrinos. We reanalyze this model in light of the latest experimental results. In contrast to the light-DM interpretation of various tentative positive signals (anomalies) that is now seriously challenged by the negative results of the LUX experiment, the neutrino interpretation remains a viable explanation to most of the anomalies. Considering future prospects, we show that the superCDMS experiment alone, when equipped with Ge and Si detectors, will be able to detect ?b and discriminate the model from a light DM interpretation. In addition, we also provide the forecast for the new CRESST-II run that now operates with new detectors and diminished backgrounds.

Pospelov, Maxim; Pradler, Josef

2014-03-01

62

Experimental results on atomic oxygen corrosion of silver  

NASA Technical Reports Server (NTRS)

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.

Fromhold, Albert T.

1988-01-01

63

Strain Energy During Mechanical Milling: Part II. Experimental  

NASA Astrophysics Data System (ADS)

The strain energy stored in mechanically milled 5083 Al powders was investigated using two experimental approaches: thermal and microstructural analysis. The experimental results show that mechanically milled 5083 Al powders store strain energy on the order of a few tens of joules per gram. These experimental results are consistent with the calculated strain energy stored in mechanically milled powders. The experimentally measured strain energy stored in powders increases with an increase in attritor diameter, impeller's rotational frequency, and ball-to-powder mass ratio; however, it decreases with an increase in ball diameter. These trends were in good agreement with the calculated strain energy stored in powders as a function of the corresponding processing parameters.

Lin, Yaojun; Yao, Bo; Zhang, Zhihui; Li, Ying; Sohn, Yongho; Schoenung, Julie M.; Lavernia, Enrique J.

2012-11-01

64

Experimental Results for an Annular Aerospike with Differential Throttling  

NASA Technical Reports Server (NTRS)

Marshall Space Flight Center funded an internal study on Altitude Compensating Nozzles (ACN) for aerospike engines. The experimental hardware for the engine test is described in this viewgraph presentation, as well as the results of the experiment. The results include spike wall pressures, nozzle efficiency, and side force for four nozzle configurations.

Ruf, Joseph H.; McDaniels, David M.

2003-01-01

65

Thermomechanical investigation on divertor supports for fusion experimental reactor: hydraulic experimental results  

Microsoft Academic Search

The Japan Atomic Energy Research Institute has been conducting technology development aimed at the construction of a fusion experimental reactor to follow JT-60 in Japan. The divertor plate facing the plasma is one of the components of the reactor core assembly, since it has to be operated under severe heat and particle loads and high electromagnetic forces. Thus the divertor

T Arai; R Hino; Y Muto; M Nakahira; M Shibui; K Furuya; E Tada; M Seki

1995-01-01

66

TAUM-AVIATION: Its Technical Features and Some Experimental Results  

Microsoft Academic Search

Upon the completion of its highly successful TAUM-METEO machine translation system, the TAUM group undertook the construction of TAUM-AVIATION, an experimental system for English to French translation in the sublanguage of technical maintenance manuals. A detailed description of the resulting prototype is offered. In particular, the paper includes: a) some figures on the size of the system; b) a description

Pierre Isabelle; Laurent Bourbeau

1985-01-01

67

HOMOPOLAR LINEAR SYNCHRONOUS MOTOR: STEADY STATE ANALYSIS AND EXPERIMENTAL RESULTS  

Microsoft Academic Search

The main electrical and mechanical performances of a homopolar linear synchronous motor (HLSM) are calculated using classical theories which are usually applied to rotating synchronous machines. An experimental study on a low-power test motor permits the verification of theoretical results. It cranes to evidence that simple theories are applicable under certain conditions to such a motor of original conception. A

Y. BAUDON; A. EL ZAWAWI; M. IVANES

1981-01-01

68

Extracting Patterns from Guitar Accompaniment Data: Some Experimental Results  

Microsoft Academic Search

The analysis of expressive performance, an important research topic in Computer Music, is almost exclusively devoted to the study of western classi- cal piano music. Instruments like the acoustic guitar and styles like Bossa Nova and Samba have almost never been studied, despite their harmonic and rhyth- mic richness. This paper describes some experimental results obtained with the extraction of

Ernesto Trajano de Lima; Søren Tjagvad Madsen; M ´ arcio Dahia; Gerhard Widmer; Geber Ramalho

69

Underactuated dynamic positioning of a ship-experimental results  

Microsoft Academic Search

The paper considers the dynamic positioning problem for a ship having only two independent controls, namely surge force and yaw moment. A time-varying feedback control law including integral action is developed and proved to exponentially stabilize both the North and East positions and the orientation of the ship. Experimental results are presented were the controller is implemented on a model

Kristin Y. Pettersen; Thor I. Fossen

2000-01-01

70

Toward implantable glucometer: Design, modeling and experimental results.  

PubMed

We put forward an implantable glucometers using a biologically inspired sensor (BioS) method. In this method, engineered glucokinase (GLK) molecules are used as nanoscale glucometers. Herein, we describe two computational and experimental models of GLKs exposed to glucose molecules. The simulation results significantly show the detection of GLK binding to glucose. We thereafter reveal the applicability of this technique for continuous glucose monitoring by demonstrating and discussing the experimental results. Based on these results the glucose measurement with various glucose concentrations (0.5 mM, 1 mM and 2.5 mM) were precisely performed and repeated for more than 4 weeks. These results prove the advantage of proposed BioS method for continuous measurement of glucose. PMID:24111021

Ghafar-Zadeh, Ebrahim; Gholamzadeh, Bahareh; Awwad, Falah; Sawan, Mohamad

2013-01-01

71

Design and experimental results for the S809 airfoil  

SciTech Connect

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.

Somers, D.M. [Airfoils, Inc., State College, PA (United States)] [Airfoils, Inc., State College, PA (United States)

1997-01-01

72

Design and experimental results for the S805 airfoil  

SciTech Connect

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.

Somers, D.M. [Airfoils, Inc., State College, PA (United States)

1997-01-01

73

Initial experimental results using the noise correlation radar  

NASA Astrophysics Data System (ADS)

Experimental results from recent field testing with the noise correlation radar (NCR) are presented as a proof of concept. In order to understand the effectiveness of the NCR, a predetermined set of measures is established. We discuss the three experimental configurations used in evaluating the system's range resolution/error, robustness to interference, and secure radio frequency (RF) emission. We show that the advanced pulse compression noise (APCN) radar waveform has low range measurement error, is robust to interference, and is spectrally nondeterministic. In addition, we determine that an improvement in range resolution due to phase modulation is achieved as a function of the random code length rather than the compressed pulse length.

Govoni, Mark A.; Silvious, Jerry; Clark, John; Overman, Charles

2013-05-01

74

A Comparison of Experimental and Theoretical Results for Magnetic Bearings  

NASA Technical Reports Server (NTRS)

A comprehensive program was undertaken to experimentally characterize the static and dynamic characteristics of a heteropolar magnetic bearing and to develop nonlinear theoretical models capable of accurately predicting magnetic bearing performance. This paper presents the results for the static characteristics of the magnetic bearing and a comparison with the predictions from the analytical model. The results indicate that the nonlinear theoretical model can accurately predict the static characteristics of the magnetic bearing.

Hibbs, Robert I., Jr.; Scharrer, Joseph K.; Galvin, Bonnie A.; Galvin, Mark W.

2000-01-01

75

Experimental results of a continuous wave laser radar system  

NASA Technical Reports Server (NTRS)

A 1.06 micron CW laser radar system was used to establish the feasibility of remotely measuring sea surface wind magnitude and direction. Simultaneous correlation of collected laser data with the environment was established by using meteorological instruments. The experimental system and methods of analysis are summarized. Results of the experiments, including wind magnitude and direction correlation, are reported. Results are compared with theoretical predictions.

Petri, K. J.; Starry, R. F.

1975-01-01

76

Experimental results for a hypersonic nozzle/afterbody flow field  

NASA Technical Reports Server (NTRS)

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.

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

1995-01-01

77

Experimental Study of Energy Distribution in Double Photon Compton Scattering  

SciTech Connect

The energy distribution of gamma photons scattered in double photon Compton scattering is measured experimentally for 0.662-MeV incident gamma photons. The two simultaneously emitted gamma quanta are investigated using a slow-fast coincidence technique. The experimental data on energy distribution do not suffer from inherent energy resolution of the gamma detector and confirm the continuous nature of energy spectra for the emitted photons. The present results are in agreement with the current theory of this higher-order process.

Dewan, R.; Saddi, M.B.; Sandhu, B.S.; Singh, B.; Ghumman, B.S. [Punjabi University (India)

2002-06-15

78

On the interpretation of the results of the experimental test of the Askar'yan effect  

NASA Astrophysics Data System (ADS)

The effect of the environment on the results of measuring the radio radiation spectrum is considered in the experimental simulation of the cascade shower by a high-energy ?-ray beam in a dense medium. The calculation shows that the character of the measured energy spectrum depends on the location of the receiving antenna with respect to the shower axis.

Filonenko, A. D.

2009-06-01

79

Epitaxial growth of metals: Experimental results and Monte Carlo simulation  

NASA Astrophysics Data System (ADS)

Layer-by-layer growth of epitaxial systems has been studied with Monte Carlo (MC) simulations, and the results have been compared with those of thermal energy atom scattering (TEAS). This technique has proved to be purely kinematical and sensitive only to defects in the outermost layers, thus allowing for a direct comparison with MC results.

Ferrón, J.; Gallego, J. M.; Cebollada, A.; De Miguel, J. J.; Ferrer, S.

1989-04-01

80

Solar activity variations of ionosonde measurements, experimental and modeling results  

NASA Astrophysics Data System (ADS)

11-year time series of hourly electron density profiles N h obtained at midlatitude station Ebro 40 5N 0 5E have been used to obtain the typical N h profiles on a monthly basis Typical profiles are used to extract both the typical bottomside parameters TBP and the ionospheric variability as function of height IVH The experimental results of the daily seasonal and solar cycle variations of TBP are compared with the model results of predicted bottomside parameters by IRI-2001model International Reference Ionosphere The above comparisons shows significant disagrements and indicates a solar cycle bias of IRI-2001 model A local model simulating the daily seasonal and solar activity dependence of experimental TBP improves the IRI-2001 prediction by factor of two The experimental results of IVH reflects the contribution to the ionospheric variability from different sources at periods lower than 30 days These results show a distinct daily seasonal and altitude pattern of variability As expected the larger variability occurs during night-time there being much better expressed at the base of the F-region Typical values of percentage of variability at altitudes of the electron density maximum are 10-20 whereas they can be as large as 50 during night-time at the base of the F region The systematic daily seasonal and long-term variability are discussed in terms of potential modeling purposes The potential physical causes driving systematic behavior of variability are discussed also

Altadill, D.

81

Validation of Magnetic Flux Leakage Computational Results against Experimental Data  

NASA Astrophysics Data System (ADS)

Results of detailed experimental measurements of the leaked magnetic field for two different steel plates with a machined notch presented in a companion paper are compared against the numerical predictions using commercial software COMSOL. The accuracy of the results is discussed in detail, as well as the ingredients that allow obtaining satisfactory computational results. Some interesting conclusions that derive from the numerical computations are also presented. For instance, the influence of the notch length on the amplitude of the recorded signal, the need to have a precise measurement of the magnetic permeability up to magnetic fields much higher than the magnetic field in the bulk of the material, etc.

Etcheverry, J. I.; Sánchez, G. A.

2011-06-01

82

Flicker in erythrocytes. II. Results of experimental studies  

Microsoft Academic Search

The phenomenon of stochastic low-frequency oscillations of erythrocyte cell membrane, termed usually the flicker of erythrocytes,\\u000a is reviewed. The first part [Biol. Membrany (Rus.), 2009, vol. 26, no. 5, pp. 352–369] describes theoretical models of erythrocyte flickering and the registration techniques.\\u000a In the second part presented below the main experimental results are reviewed, the problem of identification of acting mechanisms

V. L. Kononenko

2009-01-01

83

High performance Doppler-inertial navigation-experimental results  

Microsoft Academic Search

This paper presents experimental results from a number of performance verification sea tests of the MARPOS(R) Doppler-inertial navigation system jointly implemented by Maridan A\\/S, Denmark, and the Technical University of Denmark for use onboard the MARIDAN series of AUVs. MARPOS(R) is a dead-reckoning based navigation system, the core of which is a state-of-the-art ring laser gyro (RLG) and a Doppler

Mikael Bliksted Larsen; Maridan AIS; Agem Alle

2000-01-01

84

Novel results on low energy neutrino physics  

NASA Astrophysics Data System (ADS)

Many progresses have been achieved in the study of low energy neutrinos from Sun and Earth. In the solar neutrinos the flux from 7Be has been measured with a total error <5% (introducing strong constraints also on the pp flux), while the day/night effect in that energy region has been determined at 1%. The 8B neutrinos have been detected with a threshold down to 3 MeV, while the solar neutrinos flux from pep reaction has been measured together with a stringent limit on CNO. These results give the experimental proof of the neutrino oscillation in vacuum and the validation of the MSW-LMA model in that region, while the day/night allows the isolation of the LMA solution by means of the solar neutrinos only, without the assumption of CPT symmetry. The evidence of the antineutrinos produced within the Earth by radioactive decays is now very robust, but more statistics is needed to clearly estimate the radiogenic contribution to the terrestrial caloric energy.

Bellini, Gianpaolo

2012-07-01

85

Mechanical properties of triaxially braided composites: Experimental and analytical results  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

86

Artificial buzzing lips and brass instruments: experimental results.  

PubMed

Experimental results of a special artificial trombone player are presented: A mechanical device is a substitute for the musician. Wind instruments, and particularly the brass, are self-sustained oscillators. The oscillations are induced by a mechanical oscillator (the lips of the player) acting as a valve which modulates the flow. Measured mechanical parameters of the artificial buzzing lips for different "embouchures of the player" are presented, and analyzed in connection with the played frequencies obtained for the same "embouchures." The results are obtained with two resonator systems (a mouthpiece alone and a trombone with its mouthpiece). PMID:9745745

Gilbert, J; Ponthus, S; Petiot, J F

1998-09-01

87

Experimental Results for Titan Aerobot Thermo-Mechanical Subsystem Development  

NASA Technical Reports Server (NTRS)

This paper presents experimental results on a set of 4 thermo-mechanical research tasks aimed at Titan and Venus aerobots: 1. A cryogenic balloon materials development program culminating in the fabrication and testing of a 4.6 m long blimp prototype at 93K. 2. A combined computational and experimental thermal analysis of the effect of radioisotope power system (RPS) waste heat on the behavior of a helium filled blimp hull. 3. Aerial deployment and inflation testing using a blimp 4. A proof of concept experiment with an aerobot-mounted steerable high gain antenna These tasks were supported with JPL internal R&D funds and executed by JPL engineers with substantial industry collaboration for Task #1, the cryogenic balloon materials

Pauken, Michael T.; Hall, Jeffery L.

2006-01-01

88

Design and experimental results for the S814 airfoil  

SciTech Connect

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.

Somers, D.M. [Airfoils, Inc., State College, PA (United States)

1997-01-01

89

Recent experimental results with uranium fragments at the FRS  

NASA Astrophysics Data System (ADS)

New experimental results were obtained with relativistic exotic nuclei produced via uranium projectile fragmentation and projectile fission at the in-flight separator FRS. 60 neutron-rich isotopes have been discovered in the element range from Nd to Ac and their production cross sections have been measured. In other experimental campaigns the fragments were separated in flight and injected into the storage-cooler ring ESR for accurate mass- and lifetime measurements. New mass values have been measured for 33 nuclides in the element range from Pt to U circulating in the ESR. The systematic error has been reduced to about 10 keV which was possible by a new evaluation method.

Geissel, H.

2012-10-01

90

Comparison the Results of Numerical Simulation And Experimental Results for Amirkabir Plasma Focus Facility  

NASA Astrophysics Data System (ADS)

In this paper the results of the numerical simulation for Amirkabir Mather-type Plasma Focus Facility (16 kV, 36?F and 115 nH) in several experiments with Argon as working gas at different working conditions (different discharge voltages and gas pressures) have been presented and compared with the experimental results. Two different models have been used for simulation: five-phase model of Lee and lumped parameter model of Gonzalez. It is seen that the results (optimum pressures and current signals) of the Lee model at different working conditions show better agreement than lumped parameter model with experimental values.

Goudarzi, Shervin; Amrollahi, R.; Niknam Sharak, M.

2014-06-01

91

ANOVA parameters influence in LCF experimental data and simulation results  

NASA Astrophysics Data System (ADS)

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 simulations have been used to assess specimens life by means of several damage models implemented in two dedicated softwares. One of them is commercial life estimation software and the second one has been developed by the present research group. The life estimations results obtained from the two softwares and from the damage models have been compared with experimental duration in different test conditions. A statistical analysis of life estimation results allowed evaluating the effectiveness of the procedure.

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

2010-06-01

92

Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis  

NASA Astrophysics Data System (ADS)

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.

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

2010-06-01

93

Experimental Measurement of Low Energy Neutrino Interactions  

SciTech Connect

Neutrino interactions in the few to few tens of MeV range are of importance for several physics topics, including solar, supernova and reactor neutrinos, as well as future proposed oscillation and Standard Model test experiments. Although interaction cross-sections for some simple targets are well understood, very little experimental data exist for interactions with nuclei. This talk will discuss the motivation for measuring low energy neutrino interactions, the state of knowledge, and possible future strategies.

Scholberg, Kate [Duke University, Durham, NC, 27708 (United States)

2011-11-23

94

Single And Double Pulse Irradiation And Comparison With Experimental Results  

SciTech Connect

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.

Fornarini, L.; Fantoni, R.; Colao, F. [ENEA, FIM-FISLAS, Via E. Fermi 45, I-00044, Frascati (Italy); Santagata, A. [CNR-IMIP Unita Operativa di Potenza, Zona Industriale-85050 Tito Scalo (Italy); Teghil, R. [Universita degli Studi della Basilicata, Dip. Chimica, Via N. Sauro 85, 85100 Potenza (Italy)

2009-09-27

95

Experimental determination of stress variation threshold resulted in earthquake triggering  

NASA Astrophysics Data System (ADS)

There are many field observations of earthquake triggering by static and dynamic stress variations caused by impact of distant strong earthquakes, underground chemical and nuclear explosions, solar-lunar earth tides, strong variations of atmospheric pressure etc., as well as by electric current injection into the Earth crust. It is supposed that the external impacts on the earthquake source result in exceeding the threshold stress and earthquake triggering. Nevertheless, the mechanisms of the earthquake triggering phenomena is not clear, and the problem of determination of stress variation threshold resulted in initiation of seismic events is very important. At present, based on analysis of field observations of dynamic triggering of earthquakes (by wave train from distant strong earthquakes) performed for various regions, including the USA, Japan, China, Greece, etc. it is considered that the triggering threshold of stress variations is about of 500 kPa. An experimental study at the spring-slider system was carried out for detailed study of behavior of fault area under near-to-failure state and experimental triggering impacts, as well as for determination of the threshold variation of normal stress in the fault gauge resulted in earthquake (slip) triggering. The spring-slider system provides a spring loading rate of 0.001 to 0.02 mm/s. The travelling block of dimensions 250x120x65 mm is connected with electromechanical drive via the spring with 9.5 N/mm spring constant. The normal stress of the travelling block is up to 30 kPa. For determination of the triggering threshold of normal stress variations the electromagnetic system was activated by control system at the level of 0.98-0.99 critical (fault failure) shear stress, which provided reducing the normal stress (by 0.001% to 0.1%) in the form of rectangular pulses of 0.5 to 5.0 s duration generated in time interval of 20 to 40 s. The level of stress variation impact resulted in the slip of travelling block (with stable time delay after the pulse initiation) is considered as the threshold for the present experimental "stick-slip" system. The measured triggering threshold of normal stress variations in the fault simulator is 0.05% to 0.10%. An implication of obtained threshold values for various earthquake mechanisms is discussed.

Novikova, Elena; Novikov, Victor; Okunev, Vladimir; Klyuchkin, Vadim

2014-05-01

96

Model-assisted placement of subresolution assist features: experimental results  

NASA Astrophysics Data System (ADS)

Lithography models calibrated from experimental data have been used to determine the optimum insertion strategy of sub-resolution assist features in a 130 nm process. This work presents results for 3 different illumination types: Standard, QUASAR, and Annular. The calibrated models are used to classify every edge in the design based on its optical properties (in this case image-log-slope). This classification is used to determine the likelihood of an edge to print on target with the maximum image-log-slope. In other words, the method classifies design edges not in geometrically equivalent classes, but according to equivalent optical responses. After all the edges are classified, a rule table is generated for every process. This table describes the width and separation of the assist features based on a global cost function for each illumination type. The tables are later used to insert the assist features of various widths and separations using pre-defined priority strategies. After the bars have been inserted, OPC is applied to the main structures in the presence of the newly added assist features. Critical areas are tagged for increased fragmentation allowing certain areas to receive the maximum amount of correction and compensate for any proximity effects due to the sub-resolution assist features. The model-assisted solution is compared against a traditional rule-based solution, which was also derived experimentally. Both scenarios have model based OPC correction applied using simulation and experimental data. By comparing both cases it is possible to assess the advantages and disadvantages of both methods.

Brist, Travis E.; Torres, Juan A.

2003-07-01

97

Interpretation of PISCES -- A RF antenna system experimental results  

SciTech Connect

The paper describes experimental data from rf coupling experiments using one to four coil antenna arrays that encircle a linear magnetized plasma column. Experimental results using single turn coil that produce symmetric (i.e. m = 0), dipole (m = 1), and radial rf magnetic fields for coupling to ion waves are compared. By operating without a Faraday shield, it was observed for the first time that the plasma resistive load seen by these different antenna types tends to increase with the number of turns to at least the second power. A four-turn m = 0 coil experienced a record 3--5 {Omega} loading, corresponding to over 90% power coupling to the plasma. A four-turn m = 1 coil experienced up to 1--1.5 {Omega} loading, also higher than previous observations. First time observations using a two coil array of m = 0 coil are also reported. As predicted, the loading decreases with increasing phase between coil from 0{degree} to 180{degree}. Experiments using four coil arrays were difficult to optimize and interpret primarily due to complexity of the manual tuning. To facilitate this optimization in the future, a proposed feedback control system that automatically matches load variations between 0.2 and 10 {Omega} is described.

Rothweil, D.A.; Phelps, D.A. [General Atomics, San Diego, CA (United States); Doerner, R. [Univ. of California, San Diego, CA (United States)

1995-10-01

98

Aeolian Simulations: A Comparison of Numerical and Experimental Results  

NASA Astrophysics Data System (ADS)

Aeolian processes are a major geomorphic agent on solid planetary bodies with atmospheres (Earth, Mars, Venus, and Titan). This paper describes preliminary efforts to model aeolian saltation using computational fluid dynamics (CFD) and to compare the results with those obtained in wind tunnel testing conducted in the Planetary Aeolian Laboratory at NASA Ames Research Center at ambient pressure. The end goal of the project is to develop an experimentally validated CFD approach for modeling aeolian sediment transport on Titan and other planetary bodies. The MARSWIT open-circuit tunnel in this work was specifically designed for atmospheric boundary layer studies. It is a variable-speed, continuous flow tunnel with a test section 1.0 m by 1.2 m in size; the tunnel is able to operate at pressures from 10 millibar to one atmosphere. Flow trips near the tunnel inlet ensure a fully developed, turbulent boundary layer in the test section. Wind speed and axial velocity profiles can be measured with a traversing pitot tube. In this study, sieved walnut shell particles (Greeley et al. 1976) with a density of ~1.1 g/cm3 were used to correlate the low gravity conditions and low sediment density on a body of interest to that of Earth. This sediment was placed in the tunnel, and the freestream airspeed raised to 5.4 m/s. A Phantom v12 camera imaged the resulting particle motion at 1000 frames per second, which was analyzed with ImageJ open-source software (Fig. 1). Airflow in the tunnel was modeled with FLUENT, a commercial CFD program. The turbulent scheme used in FLUENT to obtain closed-form solutions to the Navier-Stokes equations was a 1st Order, k-epsilon model. These methods produced computational velocity profiles that agree with experimental data to within 5-10%. Once modeling of the flow field had been achieved, a Euler-Lagrangian scheme was employed, treating the particles as spheres and tracking each particle at its center. The particles are assumed to interact with wall boundaries via perfectly elastic collisions. Calculated particle trajectories agree closely with experimental results (Fig. 2).

Mathews, O.; Burr, D. M.; Bridges, N. T.; Lyne, J. E.; Marshall, J. R.; Greeley, R.; White, B. R.; Hills, J.; Smith, K.; Prissel, T. C.; Aliaga-Caro, J. F.

2010-12-01

99

Experimental feature in the primary-proton flux at energies above 10 TeV according to the results of searches for primary particles in nuclear emulsions exposed in the stratosphere (RUNJOB Experiment)  

SciTech Connect

In the RUNJOB experiment, a long-term exposure of x-ray emulsion chambers in the stratosphere from 1995 to 1999 with the aim of studying the composition and spectra of primary cosmic particles in the energy range 10-1000 TeV per nucleon revealed about 50% proton tracks. The remaining events of the proton group did not feature any candidate for a track of a singly charged particle within the search region determined from measurements of the coordinates of background nuclei going close to the sought track. Methodological factors that could explain this experimental observation are considered. A possible physical reason associated with the presence of a neutral component in the flux of primary protons in the energy region above 10 TeV is also analyzed.

Zayarnaya, I. S. [Russian Academy of Sciences, Lebedev Institute of Physics (Russian Federation)

2008-02-15

100

Registration of multimodal brain images: some experimental results  

NASA Astrophysics Data System (ADS)

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.

Chen, Hua-mei; Varshney, Pramod K.

2002-03-01

101

Beta decay and the origins of biological chirality - Experimental results  

NASA Technical Reports Server (NTRS)

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

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

1982-01-01

102

Integrated radar-camera security system: experimental results  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

103

Recent Experimental Results in the HL-2A Tokamak  

NASA Astrophysics Data System (ADS)

As the first divertor tokamak in China, HL-2A device has been successfully operated and stably sustained in the single-null divertor configuration under good feedback control of plasma current and position. Up to now, the following operation parameters have been achieved: Ip = 400 kA, Bt = 2.6 T and discharge duration Td = 2980ms. An excellent repeatability of discharge has been achieved and about 90% Greenwald density limit has been reached. The HL-2A SN divertor configuration can be simulated by the SWEQU code and identified by CCD imaging system and CF code. The experimental results proved that the divertor configuration and siliconization could strongly decrease the plasma radiation and impurity emission and reduce the recycling effectively. Density limit disruption has been analyzed and some interesting phenomena, such as asymmetric cold pulse perturbation and snake-like perturbation, have been observed during Molecular Beam Injection.

Li, W.; Yang, Q. W.; Ding, X. T.; Yan, L. W.; Shi, Z. B.; Dong, Y. B.; Yao, L. H.; Hong, W. Y.; Xuan, W. M.; Liu, D. Q.; Chen, L. Y.; Song, X. M.; Zhang, J. H.; Cao, Z.; Cui, Z. Y.; Pan, Y. D.; Duan, X. R.; Liu, Yi; Feng, B. B.; Zhou, Y.; Huang, Y.; Liu, Yong

2006-12-01

104

Guided waves in elastic plates with Gaussian section variation: experimental and numerical results.  

PubMed

Experimental and numerical results are presented on the behavior of guided waves in elastic plates in plane strain that include a Gaussian variation of their section, located between two areas of constant thickness. The area of varying section is wide compared to the used wavelengths, which allows wave propagation inside this area. The experimental results show that an incident Lamb wave is indeed converted into an adiabatic wave inside the varying section domain. A trapped wave in the Gaussian domain is also observed, depending on the incident mode and on the Gaussian maximum height. Outside the varying section domain, conversion into different Lamb waves is observed. This conversion phenomenon is experimentally quantified by the measurement of the Lamb wave normal displacement and of its carried energy. A numerical study, based on the Finite Elements Method is performed, and successfully compared to the experimental results. PMID:17659314

Marical, P; El-Kettani, M Ech-Cherif; Predoi, M V

2007-12-01

105

Experimental results from an Imarad 8×8 pixellated CZT detector  

Microsoft Academic Search

This paper reports experimental results obtained from an 8×8 pixellated CZT detector provided by Imarad Imaging Systems. Three arbitrarily selected pixels were independently tested using ? rays of different energies. The signals from an anode pixel and the cathode were read out simultaneously. From the observations of the pulse waveforms from both the anode pixel and the cathode, the electron-injection

W. Li; Z. He; G. F. Knoll; D. K. Wehe; J. E. Berry

2001-01-01

106

Experimental Results for Titan Aerobot Thermo-Mechanical Subsystem Development  

NASA Technical Reports Server (NTRS)

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.

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

107

Experimental results for Titan aerobot thermo-mechanical subsystem development  

NASA Astrophysics Data System (ADS)

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 subsequent 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

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

108

[Experimental and theoretical high energy physics program  

SciTech Connect

Experimental and theoretical high-energy physics research at Purdue is summarized in a number of reports. Subjects treated include the following: the CLEO experiment for the study of heavy flavor physics; gas microstrip detectors; particle astrophysics; affine Kac{endash}Moody algebra; nonperturbative mass bounds on scalar and fermion systems due to triviality and vacuum stability constraints; resonance neutrino oscillations; e{sup +}e{sup {minus}} collisions at CERN; {bar p}{endash}p collisions at FNAL; accelerator physics at Fermilab; development work for the SDC detector at SSC; TOPAZ; D-zero physics; physics beyond the standard model; and the Collider Detector at Fermilab. (RWR)

Finley, J.; Gaidos, J.A.; Loeffler, F.J.; McIlwain, R.L.; Miller, D.H.; Palfrey, T.R.; Shibata, E.I.; Shipsey, I.P.

1993-04-01

109

Insulator-based dielectrophoresis of microorganisms: theoretical and experimental results.  

PubMed

Dielectrophoresis (DEP) is the motion of particles due to polarization effects in nonuniform electric fields. DEP has great potential for handling cells and is a non-destructive phenomenon. It has been utilized for different cell analysis, from viability assessments to concentration enrichment and separation. Insulator-based DEP (iDEP) provides an attractive alternative to conventional electrode-based systems; in iDEP, insulating structures are used to generate nonuniform electric fields, resulting in simpler and more robust devices. Despite the rapid development of iDEP microdevices for applications with cells, the fundamentals behind the dielectrophoretic behavior of cells has not been fully elucidated. Understanding the theory behind iDEP is necessary to continue the progress in this field. This work presents the manipulation and separation of bacterial and yeast cells with iDEP. A computational model in COMSOL Multiphysics was employed to predict the effect of direct current-iDEP on cells suspended in a microchannel containing an array of insulating structures. The model allowed predicting particle behavior, pathlines and the regions where dielectrophoretic immobilization should occur. Experimental work was performed at the same operating conditions employed with the model and results were compared, obtaining good agreement. This is the first report on the mathematical modeling of the dielectrophoretic response of yeast and bacterial cells in a DC-iDEP microdevice. PMID:21853448

Moncada-Hernandez, Hector; Baylon-Cardiel, Javier L; Pérez-González, Victor H; Lapizco-Encinas, Blanca H

2011-09-01

110

RHIC PC CNI POLARIMETER: EXPERIMENTAL SETUP AND PHYSICS RESULTS.  

SciTech Connect

Acceleration of polarized proton beams and experiments with them at RHIC require fast and reliable measurements of the polarization. The polarimeter presented here uses very high figure of merit of the elastic pC scattering at very low momenta transfer since the cross section is large. Small (a few percent) analyzing power of the reaction makes it necessary to collect about 10{sup 7} events per measurement. A deadtimeless DAQ system for the polarimeter is discussed in this paper. It is based on the waveform digitizer modules with ''on-board''' event analysis, resulting in typical polarization measurement times of several tens of seconds. During winter 2001/2002 RHIC polarized run several dedicated data runs were taken by the polarimeter to extract the form of the analyzing power dependence as a function of the momentum transferred at beam energies 24 and 100 GeV. This dependence is extremely important for the theoretical understanding of the CNI process including the contribution of the spin-flip hadronic amplitude. The new data may become an input to some theoretical models predicting the energy dependence of the analyzing power.

Alekseev, I G; Bunce, G; Cadman, R; Deshpande, A; Dhawan, S; Fields, D E; Huang, H; Hughes, V; Igo, G; Imai, K; Jinnouchi, O; Kanavets, V P; Kiryluk, J; Kurita, K; Li, Z; Lozowski, W; Mackay, W W; Makdisi, Y; Rescia, S; Roser, T; Saito, N; Spinka, H; Surrow, B; Svririda, D N; Tojo, J; Underwood, D

2002-09-09

111

Experimental Results of Integrated Refrigeration and Storage System Testing  

NASA Astrophysics Data System (ADS)

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 closed cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for control of the temperature and pressure of the fluid, and enables advanced operations such as zero boil off storage and zero loss transfer. If required, this also can serve as a propellant densification system or liquefier. However, the behavior of the fluid in this type of system is different than typical cryogenic storage systems, 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 thermofluid 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.

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

2010-04-01

112

Experimental Results of Integrated Refrigeration and Storage System Testing  

NASA Technical Reports Server (NTRS)

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

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

2009-01-01

113

Experimental Results in DIS, SIDIS and DES from Jefferson Lab  

NASA Astrophysics Data System (ADS)

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.

Kuhn, Sebastian E.

2011-07-01

114

Experimental results of the European HELINOISE aeroacoustic rotor test  

NASA Astrophysics Data System (ADS)

In a cooperative research program between eight European partners, a 40% geometrically and dynamically scaled and highly instrumented model of the ECD (formerly MBB) BO 105 helicopter main rotor was tested in the open-jet anechoic test section of the German-Dutch Wind Tunnel (DNW) in the Netherlands. The primary objectives of this experimental study were to: (1) to improve the physical unsderstanding of the impulsive rotor noise sources by correlating blade pressure and acoustic character- istics, and (2) to provide an extensive airload and acoustic database for code validation purposes. Consequently, a compressive set of simultaneous acoustic and aerodynamic blade surface pressure data as well as blade dynamic and performance data were measured for the standard rotor with rectangular blade tips. In addition, initial quantitative information of the blade-vortex miss distance during blade-vortex interaction (BVI) was obtained. This paper describes the model and summarizes the aeroacoustic key results. The blade pressure chracteristics are examined to identify with the corresponding characteristics of the radiated sound pressure fields provide improved insight into the physics of the impulsive noise mechanisms. For descent flight, the strong change of BVI noise directivity and level with descent condition is illustrated, and the importance of the blade-vortex miss distance shown.

Splettstoesser, W. R.; Niesl, G.; Cenedese, F.; Nitti, F.; Papanikas, D. G.

1995-04-01

115

ICPP: Experimental Results from the Advanced Stellarator W7-AS  

NASA Astrophysics Data System (ADS)

As W7-AS resumes operation after almost a one year shutdown, it is opportune to review experimental results obtained until now. The most important goal as an advanced or partly optimized stellarator was to check some elements of the optimization scheme developed for the largely optimized W7-X presently being built in Greifswald in northern Germany. This optimization stratagem, which covers almost all aspects important for a fusion reactor, was implemented on W7-AS in only one key area - the reduction of Pfirsch-Schlueter currents, which is observable in the concurrent reduction of the Shafranov shift. The reduced Shafranov shift is important in high beta discharges where average beta values of 2Reduced Pfirsch-Schlueter currents also improve the neoclassical transport, which can be very large at high temperatures in 3D magnetic field configurations. It could be demonstrated that the 3D DKES code, taking into account trapped particle effects, can describe the experimental observations very well in cases where neoclassical transport dominates. Thus, predictions for W7-X, where neoclassical transport must be strongly diminished, should be reliable. Another aim of W7-X is to keep all pressure driven currents as small as possible in order not to perturb the optimized magnetic field configuration. In contrast, W7-AS also allows operation with large toroidal currents. The bootstrap current is large or tokamak-like and can be further enhanced by means of the ohmic heating transformer. Therefore, the stability behavior for finite toroidal currents in the presence of external poloidal fields has been a subject of investigation. Resumption of operation in the summer of 2000 is accompanied by two major modifications. The (previously counter) tangential neutral beam injector box has been shifted to a co-position, leading to an augmented heating efficiency at low magnetic fields and at high densities. Thus, higher beta values should be accessible, offering another chance to test high beta stability predictions. Secondly, all limiters have been replaced by divertor modules, with the aim to perform extensive tests of the island divertor concept foreseen for W7-X.

Jaenicke, Rolf

2000-10-01

116

[Repair mechanisms of the lung--experimental and clinical results].  

PubMed

The effect of dose and time and of the RBE on the pulmonary reaction to radiation has been studied by means of trials with young pigs. 70 animals received a fractionated (five and 15 fractions) telecobalt irradiation of the right lung over total treatment periods T of five, 23, and 35 days. The influence of dose and time on the pulmonary reaction to radiation is defined at the ED50 level (effective dose, after which 50% of animals will suffer from radiopathy) by a proportionality of D approximately N0.32 X T0.05. An alpha/beta value of 3.7 Gy is calculated according to the LQ model. An RBE value of 4.0 to 4.1 was determined in 38 animals treated over five and 35 days with the 6.2 MeV neutrons of the cyclotron Rossendorf. The experimentations on animals allow to classify the lung reaction as late effect. The clinical results found in literature show that this classification is also valid for human lung reaction to fractionated radiotherapy. So it is not possible to achieve a considerable increase of the pulmonary tolerance dose by increasing the total treatment period. The best sparing of the respiratory organ is obtained by an application of small single doses which allows to profit from the large repair capacity of pulmonary tissue. These results, as well as our considerations regarding the latent time between therapy and lung reaction, and some trials on laboratory rodents allow to speak of a radiogenic pneumopathy with the proprieties of a late reaction characterized by a pneumonitis appearing previously and changing into pulmonary fibrosis. PMID:3603364

Herrmann, T; Voigtmann, L; Knorr, A; Lorenz, J

1987-06-01

117

Stemming Temperature Changes During Emplacement: Experimental Results and Analysis.  

National Technical Information Service (NTIS)

The process of stemming a deep hole with magnetite, which was initially hotter or cooler than the ambient downhole temperature, was investigated experimentally. The specific objective of the experiment was to determine the temperature changes that occur a...

W. Stein W. J. Comfort

1989-01-01

118

Equatorial spread-F - A review of recent experimental results  

Microsoft Academic Search

A review is presented of a number of experimental verifications of the Rayleigh-Taylor instability as related to the generation of the topside equatorial spread-F, and a synthesis of the observations is made with parallel theoretical developments. Experimental verification of a number of hypotheses is given, and it is shown that: (1) radar plumes are co-located with the topside depletions in

M. C. Kelley; J. P. McClure

1981-01-01

119

Experimental setup for high energy photoemission using synchrotron radiation  

NASA Astrophysics Data System (ADS)

The instrument VOLPE (volume photoemission from solids) is an experimental setup dedicated to high energy photoemission (PE) experiments. The instrument is equipped with an electrostatic hemispherical spectrometer especially designed to analyze high energy electrons (up to 10 keV) with high resolving power. In order to attain an energy resolution of a few tens of millielectron volts, we designed and constructed a dedicated input lens system, high stability power supplies, and a low dark-count detector and readout electronics. The system has been tested and is now operational on the ID16 beamline at European Synchrotron Radiation Facility, where an optical layout has been developed to perform high energy, high resolution PE experiments. First results show an overall energy resolution (electron + photon) of 71+/-7 meV at 5934 eV. The effective attenuation length of the photoelectrons is estimated to be 5+/-0.5 nm at a kinetic energy of 5 keV.

Torelli, P.; Sacchi, M.; Cautero, G.; Cautero, M.; Krastanov, B.; Lacovig, P.; Pittana, P.; Sergo, R.; Tommasini, R.; Fondacaro, A.; Offi, F.; Paolicelli, G.; Stefani, G.; Grioni, M.; Verbeni, R.; Monaco, G.; Panaccione, G.

2005-02-01

120

Bolus-tracking arterial spin labelling: theoretical and experimental results.  

PubMed

Arterial spin labelling (ASL) is a magnetic resonance imaging (MRI) technique that can be used to provide a quantitative assessment of cerebral perfusion. Despite the development of a number of theoretical models to facilitate quantitative ASL, some key challenges still remain. The purpose of this study is to develop a novel quantitative ASL method based on a macroscopic model that reduces the number of variables required to describe the physiological processes involved. To this end, a novel Fokker-Planck equation consisting of stochastically varying macroscopic variables was derived from a general Langevin equation. ASL data from the rat brain was acquired using a bolus-tracking ASL protocol where a bolus of labelled spins flowing from an inversion plane in the neck into an imaging plane in the brain can be observed. Bolus durations of 1.5 s, 2.0 s and 3.0 s were used and the solution to the Fokker-Planck equation for the boundary conditions of bolus-tracking ASL was fitted to the experimental data using a least-squares fit. The mean transit time (MTT) and capillary transit time (CTT) were calculated from the first and second moments of the resultant curve respectively and the arterial transit time (ATT) was calculated by subtracting the CTT from the MTT. The average MTT, CTT and ATT values were 1.75 +/- 0.22 s, 1.43 +/- 0.12 s and 0.32 +/- 0.04 s respectively. In conclusion, a new ASL protocol has been developed by combining the theoretical model with ASL experiments. The technique has the unique ability to provide solutions for varying bolus volumes and the generality of the new model is demonstrated by the derivation of additional solutions for the continuous and pulsed ASL (CASL and PASL) techniques. PMID:19182324

Kelly, M E; Blau, C W; Kerskens, C M

2009-03-01

121

Amplified energy harvester from footsteps: design, modeling, and experimental analysis  

NASA Astrophysics Data System (ADS)

This paper presents the design, modeling and experimental analysis of an amplified footstep energy harvester. With the unique design of amplified piezoelectric stack harvester the kinetic energy generated by footsteps can be effectively captured and converted into usable DC power that could potentially be used to power many electric devices, such as smart phones, sensors, monitoring cameras, etc. This doormat-like energy harvester can be used in crowded places such as train stations, malls, concerts, airport escalator/elevator/stairs entrances, or anywhere large group of people walk. The harvested energy provides an alternative renewable green power to replace power requirement from grids, which run on highly polluting and global-warming-inducing fossil fuels. In this paper, two modeling approaches are compared to calculate power output. The first method is derived from the single degree of freedom (SDOF) constitutive equations, and then a correction factor is applied onto the resulting electromechanically coupled equations of motion. The second approach is to derive the coupled equations of motion with Hamilton's principle and the constitutive equations, and then formulate it with the finite element method (FEM). Experimental testing results are presented to validate modeling approaches. Simulation results from both approaches agree very well with experimental results where percentage errors are 2.09% for FEM and 4.31% for SDOF.

Wang, Ya; Chen, Wusi; Guzman, Plinio; Zuo, Lei

2014-04-01

122

Vortex Threshold: Experimental Results at Martian Atmospheric Pressures  

NASA Astrophysics Data System (ADS)

Many examples of Martian dust devils and tracks left by their passage have been identified in Viking and Mars Orbital Camera images and inferred from lander data (Viking and Mars Pathfinder). Recent surveys suggest that dust devils may be common phenomena on Mars and, unlike Earth, could contribute significantly to the global dust budget. Previous studies have noted the apparent paradox that Martian airborne dust is abundant and only a few microns in diameter yet experiments at Mars pressures suggest current Martian ambient wind speeds are insufficient to lift such fine particles from the surface; speeds of the order of 10s or even 100s of m/s are required. Local wind speeds within terrestrial dust devils are typically much greater than ambient wind speeds, but we have no in-situ measurements of the velocity structure of Mars dust devils and so cannot directly quantify their ability to entrain material. However, by using laboratory simulations we can directly measure the ability of a vortex to lift material of known size and density under a variety of atmospheric pressures. We have constructed a vortex generator consisting of a large vertical cylinder containing a rotor comprising four vertical blades and capable of speeds up to 4500 RPM. Beneath the cylinder is a 2.4 by 2.4 m tabletop which can be covered in particles for threshold tests or instrumented with pressure transducers to measure the pressure structure of the vortex. The distance between the cylinder and the tabletop and the height of the blades within the cylinder can be varied to generate a wide range of geometries and intensities of vortices. Recently, the apparatus has been operated at the NASA-Ames Research Center Mars Surface Wind Tunnel facility to simulate Martian atmospheric conditions. We have measured vortex `saltation' threshold using many types of particles ranging in density from walnut shells (1.1 kg/m-3) to steel grit (7.6 kg/m-3) with particle sizes from 2 to 2000 microns and using atmospheric pressures ranging from 10 mbar (representing current Mars atmospheric conditions) to ambient. As expected, vortex threshold was more difficult to achieve with lower pressure conditions. Only the `optimum' particles (those with low densities and particle sizes ranging from 70 to 350 micron) reached full `saltation' at 10 mbar pressure before the apparatus speed limit was reached. Our results suggest that vortex threshold is directly analogous to boundary layer shear threshold for sand-sized particles at pressure from 65 mbar to ambient. We have used this result to equate vortex and boundary layer results in the sand-sized particle regime and hence to compare vortex threshold data with boundary layer results for smaller particles and lower pressures. We used empirical boundary layer expressions for threshold (corrected for particle size and particle Reynold's number). In all cases, vortex action appears more efficient than boundary layer winds at lifting small dust-sized particles and at lifting all particles at very low pressure. We conclude that Martian dust devils are more efficient mechanisms for particle entrainment than boundary layer winds, not merely because they have enhanced local wind speeds but also through another intrinsic mechanism. We suggest that a lift force caused by the passage of the low-pressure core of the dust devil over the particles would have such an effect and present examples of experimental `pressure-well' measurements at low pressures to support this.

Balme, M.; Greeley, R.; Phoreman, J.; Iversen, J.; Mickelson, B.; Beardmore, G.; Metzger, S.

2002-12-01

123

Experimental results on frost as a first wall shielding concept for inertial confinement fusion  

SciTech Connect

An experimental effort was undertaken at the Energy Technology Engineering Center in support of the design of the Laboratory Microfusion Facility (LMF) by Lawrence Livermore National Laboratory. The purpose of the experiments was to determine the ability of a frost-covered wall to act as a first wall in the LMF for the absorption of x-rays and debris. Certain aspects of the frost shielding concept were verified including growth rate, thermal conductivity, crush strength, ability to absorb shock waves and withstand vibration, and integrity after growth. The experimental results indicate that frost would function as a suitable first wall for the LMF. 87 figs.

Neely, H.H.; Hoffman, N.J.; Murray, K.A.

1990-03-01

124

Report on Results Achieved with Seas Experimental Mill.  

National Technical Information Service (NTIS)

The SEAS experimental windmill was built in order to attempt operation of a three-phase alternating current generator with a wind turbine as drive power in conjuction with existing ac installations. Testing in natural wind was carried out on the wing shap...

J. Juul

1974-01-01

125

[Computed tomography of patellar chondropathy. Experimental and clinical results].  

PubMed

Experimental studies of patellae at autopsy and clinical CT-arthrographic examinations of 36 patients show that CT provides good demonstration of the retropatellar cartilage and its lesions. The value of the method compared with conventional radiographic examinations, arthroscopy and surgery is discussed. PMID:6421696

Lingg, G; Hering, L

1983-12-01

126

New experimental results on the gyro-TWT with a helically grooved waveguide  

Microsoft Academic Search

Experimental results are presented for a frequency-broadband efficient gyrotron traveling wave tube based on a novel microwave system in the form of a waveguide with a helical corrugation of its inner surface. The gyro-TWT utilizes a low-relativistic axis-encircling electron beam with an energy up to 80 keV, current up to 10 A and pulse duration up to 10 ?s, which

V. L. Bratman; G. G. Denisov; V. N. Manuilov; G. I. Kalynova; M. M. Ofitserov; S. V. Samsonov; A. B. Volkov

2002-01-01

127

Active vibration and structural acoustic control of shape memory alloy hybrid composites - Experimental results  

Microsoft Academic Search

A development-status evaluation is presented for active control techniques employing shape-memory alloy hybrid composites. Attention is given to experimental results for: (1) active dynamic tuning via 'active strain-energy tuning' (ASET); (2) active control of sound radiation from a clamped-baffled beam; and (3) transient vibration control of a cantilevered beam. ASET is shown to be a viable method for the modification

Craig A. Rogers

1990-01-01

128

Overweighing Recent Observations: Experimental Results and Economic Implications  

Microsoft Academic Search

We conduct an experimental study in which subjects choose between alternative risky investments. Just as in the “hot hands”\\u000a belief in basketball, we find that even when subjects are explicitly told that the rates of return are drawn randomly and\\u000a independently over time from a given distribution, they still assign a relatively large decision weight to the most recent\\u000a observations

Haim Levy; Moshe Levy

129

Experimental Results for an Annular Aerospike with Differential Throttling  

NASA Technical Reports Server (NTRS)

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.

Ruf, Joseph H.; McDaniels, David M.

2005-01-01

130

CP Violation in B Meson Decays: Experimental Results  

SciTech Connect

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.

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

2005-08-30

131

Polycapillary optics: comparison of computational modeling and experimental results  

NASA Astrophysics Data System (ADS)

Polycapillary optics consist of hundreds of thousands of tiny hollow tubes that utilize total external reflection to redirect x-rays incident at grazing angles. These optics have been developed for various applications, from beam filtering to x-ray collimating or focusing. A fully three-dimensional Monte-Carlo-based ray-tracing simulation of polycapillary optics has been developed to model a variety of optics geometries. Good agreement to experimental data was found with a small number of fitting parameters.

Schmitz, R.; MacDonald, C. A.

2011-09-01

132

Laser ablation of a turbid medium: Modeling and experimental results  

SciTech Connect

Q-switched Nd:YAG laser ablation of a turbid medium (paint) is studied. The optical properties (absorption coefficient, scattering coefficient, and its anisotropy) of a paint are determined with a multiple scattering model (three-flux model), and from measurements of reflection-transmission of light through thin layers. The energy deposition profiles are calculated at wavelengths of 532 nm and 1.064 {mu}m. They are different from those described by a Lambert-Beer law. In particular, the energy deposition of the laser beam is not maximum on the surface but at some depth inside the medium. The ablated rate was measured for the two wavelengths and compared with the energy deposition profile predicted by the model. This allows us to understand the evolution of the ablated depth with the wavelength: the more the scattering coefficient is higher, the more the ablated depth and the threshold fluence of ablation decrease.

Brygo, F.; Semerok, A.; Weulersse, J.-M.; Thro, P.-Y.; Oltra, R. [Commissariat a l'Energie Atomique, DEN/DANS/DPC/SCP/LILM, Batiment 467, 91191 Gifs/Yvette (France); LRRS-UMR 5613 CNRS, Universite de Bourgogne 21078 Dijon (France)

2006-08-01

133

Supersonic combusting flow - A comparison of numerical and experimental results  

NASA Technical Reports Server (NTRS)

The flow field of an unconfined coaxial supersonic burner (SSB) was obtained numerically, using a CFD code. The explicit MacCormack algorithm, with point implicit treatment of chemistry source terms, was employed in the CFD code. Combustion of hydrogen and air was simulated by a two-step finite-rate combustion model whereas turbulence was accounted for by a Prandtl mixing length scheme. Boundary conditions and some important features of the numerical scheme were discussed. The qualitative features of the numerical solution were compared with those obtained by regular as well as schlieren photographs. General agreements of the CFD solution and the experimental photographs were observed.

Chitsomboon, T.; Rogers, R. C.; Northam, G. B.; Jarrett, O., Jr.; Antcliff, R. R.

1988-01-01

134

Optimal active vibration absorber - Design and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

135

Optimal active vibration absorber: Design and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

136

Experimental Studies of Ion Beam Neutralization: Preliminary Results  

NASA Astrophysics Data System (ADS)

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.

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

2011-05-01

137

Curcumin improves early functional results after experimental spinal cord injury  

Microsoft Academic Search

Background  Curcumin is a polyphenol extracted from the rhizome of Curcuma longa and well known as a multifunctional drug with anti-oxidative, anticancerous, and anti-inflammatory activities. The aim of\\u000a the study was to evaluate and compare the effects of the use of the curcumin and the methylprednisolone sodium succinate (MPSS)\\u000a functionally, biochemically, and pathologically after experimental spinal cord injury (SCI).\\u000a \\u000a \\u000a \\u000a \\u000a Method  Forty rats

Berker Cemil; Kivanc Topuz; Mehmet Nusret Demircan; Gokhan Kurt; Kagan Tun; Murat Kutlay; Osman Ipcioglu; Zafer Kucukodaci

2010-01-01

138

Experimental results and modeling of a dynamic hohlraum on SATURN.  

National Technical Information Service (NTIS)

Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--13...

M. S. Derzon G. O. Allshouse C. Deeney R. J. Leeper T. J. Nash

1998-01-01

139

Experimental Results of Integrated Refrigeration and Storage System Testing  

Microsoft Academic Search

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 closed cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for control of the temperature and pressure of the fluid, and enables advanced

W. U. Notardonato; W. L. Johnson; J. Oliveira; K. Jumper

2010-01-01

140

EXPERIMENTAL RESULTS OF INTEGRATED REFRIGERATION AND STORAGE SYSTEM TESTING  

Microsoft Academic Search

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 closed cycle Brayton refrigerator to remove energy from the stored cryogenic propellant. This allows for control of the temperature and pressure of the fluid, and enables advanced

W. U. Notardonato; W. L. Johnson; J. Oliveira; K. Jumper

2010-01-01

141

Hydrogen Yield Results from Experimental Arc Pyrolysis of Methane  

Microsoft Academic Search

Although hydrogen is an attractive fuel for a hypersonic airbreathing vehicle in terms of reaction rate, flame temperature, and energy content per unit mass, the substantial tank volume required to store hydrogen imposes a drag penalty to performance that tends to offset these advantages. An alternative approach is to carry a hydrocarbon fuel a nd convert it on -board into

C. M. Roseberry; D. R. Wilson; F. K. Lu

142

Medical waste to energy: experimental study  

PubMed Central

SUMMARY Objective. Although waste is traditionally assessed as a pollutant which needs to be reduced or lessened, its management is certainly necessary. Nowadays, biological fuel cells, through the direct conversion of organic matter to electricity using biocatalysts, represent a technology able to produce sustainable energy by means of waste treatment. This study aims to propose a mean to generate energy from blood and saliva, that are common risk-infectious medical waste. Materials and methods. Material employed (purchased by Sigma-Aldrich) were: Glucose oxidase (GOx), Nafion perfluorinated resin solution at 5% in a mixture of lower aliphatic alcohols and water, Polyethylene oxide. Stock solutions of D (+) glucose were prepared in a 0.1 M phosphate buffer solution and stored at 4 °C for at least 24 h before use. Carbon cloth electrode ELAT HT 140 E-W with a platinum loading of 5 gm-2 was purchased by E-Tek. Electrospun Nafion fibers were obtained as follows. Scanning electron microscopy was used to characterize the electrode morphologies. Results. In order to develop an effective immobilization strategy of GOx on the electrode surface, Nafion fibers (a fully fluorinated ion conducting polymer used as a membrane material in enzymatic fuel cells - EFC) were selected as immobilizing polymer matrix. In this work, exploiting the nafion fibers capability of being able to cathalize Gox activity, we have tried to produce an enzymatic fuel cell which could produce energy from the blood and the saliva within medical-dental waste. Conclusions. Medical waste refers to all those materials produced by the interaction among doctor and patient, such as blood and saliva. During our research we will try to complete an EFC prototype able to produce energy from blood and saliva inside the risk-infectious medical waste in order to contribute to the energy requirements of a consulting room.

ARCURI, C.; LUCIANI, F.; PIVA, P.; BARTULI, F.N.; OTTRIA, L.; MECHERI, B.; LICOCCIA, S.

2013-01-01

143

Surface electromagnetic waves in Fibonacci superlattices: Theoretical and experimental results  

NASA Astrophysics Data System (ADS)

We study theoretically and experimentally the existence and behavior of the localized surface modes in one-dimensional (1D) quasiperiodic photonic band gap structures. These structures are made of segments and loops arranged according to a Fibonacci sequence. The experiments are carried out by using coaxial cables in the frequency region of a few tens of MHz. We consider 1D periodic structures (superlattice) where each cell is a well-defined Fibonacci generation. In these structures, we generalize a theoretical rule on the surface modes, namely when one considers two semi-infinite superlattices obtained by the cleavage of an infinite superlattice, it exists exactly one surface mode in each gap. This mode is localized on the surface either of one or the other semi-infinite superlattice. We discuss the existence of various types of surface modes and their spatial localization. The experimental observation of these modes is carried out by measuring the transmission through a guide along which a finite superlattice (i.e., constituted of a finite number of quasiperiodic cells) is grafted vertically. The surface modes appear as maxima of the transmission spectrum. These experiments are in good agreement with the theoretical model based on the formalism of the Green function.

El Hassouani, Y.; Aynaou, H.; El Boudouti, E. H.; Djafari-Rouhani, B.; Akjouj, A.; Velasco, V. R.

2006-07-01

144

Exergy model of a vortex tube system with experimental results  

Microsoft Academic Search

A thermodynamic model has been used to investigate vortex tube energy separation. An equation has been derived for the rate of entropy generation. This equation is used to model the irreversibility term. A Gouy-Stodola type relation is used for the total irreversibility. The exergy-destruction rate and flow availability are estimated. A vortex-tube laboratory unit has been constructed to verify the

M. H. Saidi; M. R. Allaf Yazdi

1999-01-01

145

A first glance at the initial ATF experimental results  

SciTech Connect

In the initial phase of ATF operation, the plasma minor radius and the edge rotational transform were reduced by field errors. This caused an effective change of the magnetic configuration: it improved the stability properties but worsened the equilibrium properties. The threshold for the second stability regime was lowered to ..beta../sub 0/ /approximately/ 1.5%. Experimental profile data are compatible with operation in the second stability regime, and the achieved beta values, ..beta../sub 0/ /approximately/ 3%, are well beyond the theoretically calculated threshold. Magnetic fluctuation measurements showed the effects of beta self-stabilization. They are in reasonable agreement with the predictions of the theory and support the evidence that ATF has already operated in the second stability regime. 24 refs., 20 figs., 1 tab.

Carreras, B.A.; Dominguez, N.; Leboeuf, J.N.; Lynch, V.E.; Charlton, L.A.

1989-05-01

146

CSI Flight Computer System and experimental test results  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

147

Experimental test results of a generalized parameter fuel control  

NASA Technical Reports Server (NTRS)

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.

Batterton, P. G.; Gold, H.

1973-01-01

148

Experimental results and modeling of a dynamic hohlraum on SATURN  

SciTech Connect

Experiments were performed at SATURN, a high current z-pinch, to explore the feasibility of creating a hohlraum by imploding a tungsten wire array onto a low-density foam. Emission measurements in the 200--280 eV energy band were consistent with a 110--135 eV Planckian before the target shock heated, or stagnated, on-axis. Peak pinch radiation temperatures of nominally 160 eV were obtained. Measured early time x-ray emission histories and temperature estimates agree well with modeled performance in the 200--280 eV band using a 2D radiation magneto-hydrodynamics code. However, significant differences are observed in comparisons of the x-ray images and 2D simulations.

Derzon, M.S.; Allshouse, G.O.; Deeney, C.; Leeper, R.J.; Nash, T.J. [Sandia National Labs., Albuquerque, NM (United States); Matuska, W.; Peterson, D.L. [Los Alamos National Lab., NM (United States); MacFarlane, J.J. [Univ. of Wisconsin, Madison, WI (United States); Ryutov, D.D. [Lawrence Livermore National Lab., CA (United States)

1998-06-01

149

Experimental results of USSR nuclear explosion decoupling measurements  

SciTech Connect

This report was presented at the 14th annual PL/DARPA Seismic Research Symposium on September 16, 1992. In it, we describe a decoupling experiment undertaken by the former Soviet Union at Azghir, north of the Caspian Sea. The properties of the cavity are given, including a rough description of the geology (salt-dome overlain by 275 m radius sphere, 987 m deep), velocities, densities, etc. These shots had larger yields than the Salmon-Sterling decoupling experiments undertaken by the U.S. in the mid-sixties. Like the U.S. experiment, this Soviet experiment did not achieve full decoupling. The energy decoupling factor (computed from statistical relationships between the yield and amplitude-distance curves rather than spectra) increased to a maximum of 30 as distance increase. Based on our observations and theoretical limits to decoupling, we conclude that a fully decoupled 1 kt explosion could be observed at a distance of 2,500 km.

Adushkin, V.V.; Kitov, I.O.; Sultanov, D.D.

1992-09-01

150

Experimental Results for Steel Sphere Penetration in Gelatine.  

National Technical Information Service (NTIS)

The retardation of steel spheres when fired into gelatine is investigated. The results are compared to model prediction, which are possible to calculate analytically. The purpose of the work is eventually to use the model, or rather the penetration depths...

A. Collin G. Wijk

2000-01-01

151

[Endoscopic aortofemoral bypass reconstruction: experimental and clinical results].  

PubMed

According to the present experiences, the new videoendoscopic vascular instrument systems have fulfilled the basic requirements for performing videoendoscopic aortoiliac surgery. The animal studies (n = 25) showed clearly, that the piglet is a reproducible and favourable model to acquire the basic surgical techniques for videoendoscopic aortoiliac surgery, since its retroperitoneal anatomy is similar to that of humans. The transabdominal-retroperitoneal approach on human cadavers (n = 6) was soon abandoned, since particularly in obese cases it caused burdensome sliding of the intestine into the operative field adjacent to the renal vessels. The intensive investigations on human cadavers (n = 20) has meanwhile allowed us to constantly expose the aorta above the inferior mesenteric artery up to the left renal vessels without the need to sacrifice the inferior mesenteric artery (total operating time: 3-4.5 hours, aortic reconstruction averagely 42 minutes). The prolonged operating time during the extraperitoneal approach, especially in case of accidental tearing of the retroperitoneum has led us to evaluate the transabdominal paracolic approach (n = 6). This procedure with right-sided positioning of the patient offers a broad operating area and retains the intestine in the right side of the abdomen throughout, thus reducing the operating time in our initial 6 cases to a mean of 2.9 hours (range: 2.5-3.5 hours). As to our limited clinical experience and in accordance to other surgical groups the video assisted aortoiliac surgery (n = 12) by performing a small abdominal incision for the aortic anastomosis under direct vision seems to be an alternative procedure to the total videoendoscopic aortoiliac surgery (n = 7). Further experimental research, consistent development and refinement of videoendoscopic vascular instruments and prospective evaluation of the different videoendoscopic approaches to the aortoiliac vessels are necessary to evaluate the use of the videoendoscopic surgical technique, to clarify its advantages and to probably generalize the procedure in the near future. PMID:11253537

Said, S

2001-02-01

152

Effects of imperfect dynamic clamp: computational and experimental results.  

PubMed

In the dynamic clamp technique, a typically nonlinear feedback system delivers electrical current to an excitable cell that represents the actions of "virtual" ion channels (e.g., channels that are gated by local membrane potential or by electrical activity in neighboring biological or virtual neurons). Since the conception of this technique, there have been a number of different implementations of dynamic clamp systems, each with differing levels of flexibility and performance. Embedded hardware-based systems typically offer feedback that is very fast and precisely timed, but these systems are often expensive and sometimes inflexible. PC-based systems, on the other hand, allow the user to write software that defines an arbitrarily complex feedback system, but real-time performance in PC-based systems can be deteriorated by imperfect real-time performance. Here, we systematically evaluate the performance requirements for artificial dynamic clamp knock-in of transient sodium and delayed rectifier potassium conductances. Specifically, we examine the effects of controller time step duration, differential equation integration method, jitter (variability in time step), and latency (the time lag from reading inputs to updating outputs). Each of these control system flaws is artificially introduced in both simulated and real dynamic clamp experiments. We demonstrate that each of these errors affect dynamic clamp accuracy in a way that depends on the time constants and stiffness of the differential equations being solved. In simulations, time steps above 0.2ms lead to catastrophic alteration of spike shape, but the frequency-current relationship is much more robust. Latency (the part of the time step that occurs between measuring membrane potential and injecting re-calculated membrane current) is a crucial factor as well. Experimental data are substantially more sensitive to inaccuracies than simulated data. PMID:18076999

Bettencourt, Jonathan C; Lillis, Kyle P; Stupin, Laura R; White, John A

2008-04-30

153

Experimental Results of Ultra-Cold Neutron Production in Solid Oxygen  

NASA Astrophysics Data System (ADS)

The results of an experimental investigation of Ultra-cold neutron (UCN) production from magnetic solid oxygen are presented. Using neutrons from flight path 12 at Lujan Center, LANSCE, we study the production of UCN from the cold neutron beam at LANSCE FP12 as a function of temperature, source volume, incident neutron energy, and applied magnetic field up to 5.5 T. Results suggest UCN production from magnetic interactions with the neutron is a dominant mode of production, and that UCN from solid oxygen is comparable to that from deuterium.

Lavelle, Christopher; Liu, Chen-Yu; Shin, Yunchang; Salvat, Dan; McChesney, Patrick; Manus, Greg; Ribeill, Guilhem; Young, Albert; Morris, Chris; Makela, Mark; Saunders, Andy

2009-05-01

154

Acoustic analysis in Mudejar-Gothic churches: Experimental results  

Microsoft Academic Search

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.

Miguel Galindo; Teófilo Zamarreño; Sara Girón

2005-01-01

155

Experimental results of the APERTIF phased array feed  

Microsoft Academic Search

APERTIF (APERture Tile In Focus) is a Phased Array Feed (PAF) system that is being developed for the Westerbork Synthesis Radio Telescope (WSRT) to increase its survey speed with a factor 20. This paper presents an overview of APERTIF and measurement results that demonstrate the unique capabilities of PAFs in practice: Wide field of view (scan range), low system temperature,

W. A. van Cappellen; L. Bakker; T. A. Oosterloo

2011-01-01

156

Sheet Hydroforming Process Numerical Model Improvement Through Experimental Results Analysis  

Microsoft Academic Search

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

Papadia Gabriele; Del Prete Antonio; Anglani Alfredo

2010-01-01

157

Arago (1810): the first experimental result against the ether  

NASA Astrophysics Data System (ADS)

Ninety five years before special relativity was born, Arago attempted to detect the absolute motion of the Earth by measuring the deflection of starlight passing through a prism fixed to the Earth. The null result of this experiment gave rise to Fresnel's hypothesis of an ether partly dragged by a moving substance. In the context of Einstein's relativity, the sole frame which is privileged in Arago's experiment is the proper frame of the prism, and the null result only says that Snell's law is valid in that frame. We revisit the history of this premature first evidence against the ether theory and calculate Fresnel's dragging coefficient by applying Huygens' construction in the frame of the prism. We expose the dissimilar treatment received by the ray and the wavefront as an unavoidable consequence of the classical notions of space and time.

Ferraro, Rafael; Sforza, Daniel M.

2005-01-01

158

Experimental results on microwave pulse compression using helically corrugated waveguide  

Microsoft Academic Search

The paper presents new results on the development of a method to generate ultrahigh-power short-microwave pulses by using a known principle of compression (reduction in pulse duration accompanying with increase in pulse amplitude) of a frequency-swept wave packet propagating through a dispersive medium. An oversized circular waveguide with helical-corrugations of its inner surface ensures an eigenwave with strongly frequency dependent

M. McStravick; S. V. Samsonov; K. Ronald; S. V. Mishakin; W. He; G. G. Denisov; C. G. Whyte; V. L. Bratman; A. W. Cross; A. R. Young; P. Macinnes; C. W. Robertson; A. D. R. Phelps

2010-01-01

159

Delaminations in composite plates under transverse static loads - Experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1992-01-01

160

Transurethral microwave heating without urethral cooling: theory and experimental results  

NASA Astrophysics Data System (ADS)

Transurethral microwave hyperthermia is emerging as an important treatment modality in the management of patients with benign prostatic hyperplasia. The existing transurethral applicators are easy to operate and some have been designed to be disposable. Heating patterns measured in the laboratory and clinically are similar. There is a predictable temperature distribution clinically useful in the immediate periurethral prostate. Results of preclinical studies have been presented.

Petrovich, Zbigniew; Astrahan, Melvin; Baert, Luc

1991-07-01

161

Experimental results of a propeller/wing interaction study  

NASA Technical Reports Server (NTRS)

Steady state measurements have been performed on a propellar and a wing in a tractor configuration, to investigate the consequences of mutual interference on overall performance. For certain geometries wing lift is found to be enhanced, and wing drag to be decreased. The unsteady nature of the propeller-wing aerodynamic interaction has been studied using flow visualization. Results obtained indicate that the tip vortex is severed at the wing leading edge, the severed tip vortex filaments shear in a spanwise direction relative to one another, and these displaced filaments deform to reconnect at the trailing edge.

Johnson, Robert T.; Sullivan, John P.; Witkowski, David P.

1991-01-01

162

Delaminations in composite plates under transverse impact loads - Experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

163

Experimental Results of Guided Wave Travel Time Tomography  

NASA Astrophysics Data System (ADS)

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.

Volker, Arno; Bloom, Joost

2011-06-01

164

Mars ionosphere: A review of experimental results and modeling studies  

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

165

Experimental results of breakdown in "Dena" plasma focus device  

NASA Astrophysics Data System (ADS)

In spite of the intense research activities on Plasma Focus devices, the physics of the initial breakdown and surface discharge phase has not been realized completely. In this paper we have analyzed the surface discharge and initial breakdown phase in Filippov-type Plasma Focus Facility "Dena" (90 kJ, 25 kV) on the base of the current and current derivative measured signals by using Argon, Neon and Krypton as working gases at different discharge voltages and gas pressures, and the effects of working conditions (atomic weight, discharge voltage and gas pressure) on the breakdown and surface discharge phase have expressed. Also, on the base of these results, we have investigated about the relation of this phase with final pinch phase.

Goudarzi, Shervin; Hoseinian, S. M.; Raeisdana, A.

2014-06-01

166

Experimental results on aerofoil manipulators at high subsonic speeds  

NASA Astrophysics Data System (ADS)

An extensive series of measurements of the boundary layer development and drag downstream of aerofoil manipulators have been made in the high speed tunnels at Cambridge. This work forms part of a combined study with the University of Poitiers into the possible drag reducing properties of manipulators and was supported by Airbus Industrie. Overall the test results showed that the reduction in turbulent skin-friction downstream of the device did not compensate for the drag of the device itself in any of the cases studied, thus no overall drag saving was possible although in certain cases the overall drag penaly was small. This finding suggests that such devices may have a use in regions where a local reduction in skin-friction (and hence possible heat transfer) is needed and a low level of loss can be accepted. However, the actual drag reduction obtained was found to be extremely sensitive to changes in the aerofoil shape and incidence.

Squire, L. C.; Savill, A. M.

1996-08-01

167

Microgravity Fluid Separation Physics: Experimental and Analytical Results  

NASA Technical Reports Server (NTRS)

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.

Shoemaker, J. Michael; Schrage, Dean S.

1997-01-01

168

Dust Devils: Experimental Results for Vortex Sediment Flux  

NASA Astrophysics Data System (ADS)

Laboratory experiments using the Arizona State University Vortex Generator ("dust devil machine") yield new results in simulating the amount of sand and dust (flux) raised by dust devils. Flux experiments involved measuring mass loss from a test bed as a function of time for known vortex parameters yielding a calculated value for the flux. Sediment fluxes of dust (2 ? m in diameter), silica sands (5 sizes ranging in diameter from 90 to 500 ? m), and walnut shells (2 sizes ranging in diameter from 590 to 1700 ? m) are compared to the Reynold's number, u{? r{? }/? } (4000-18,000), and a dimensionless lifting parameter, ? P/(? pgDp), (0.001-1.0), in which u{? } and r{? } are the vortex tangential velocity and core radius, ? is the kinematic viscosity of the air, ? P is the pressure drop across the vortex, ? p and Dp are the particle density and diameter, and g is gravitational acceleration. Results show that in general, flux increases with Reynold's number and with lifting parameter. Lower-density walnut shells show a higher flux than silica sands and dust suggesting that on Mars (where g is lower) the flux would be greater in comparison to Earth. Lower-density walnut shell particles are used to simulate the lower g of Mars. Future work involves further expansion of the experiment matrix with other materials of varying sizes and densities. Use of the Mars Surface Wind Tunnel facility at NASA Ames Research Center will also allow this study to be simulated at Mars atmospheric pressures.

Neakrase, L. D.; Greeley, R.; Iversen, J. D.; Balme, M. L.; Foley, D. J.; Eddlemon, E. E.

2004-12-01

169

Overview of experimental results on the HL-2A tokamak  

NASA Astrophysics Data System (ADS)

The physics experiments on the HL-2A tokamak have been focused on confinement improvement, particle and thermal transport, zonal flow and turbulence, filament characteristics, energetic particle induced modes and plasma fuelling efficiency since 2008. ELMy H-mode discharges are achieved in a lower density regime using a combination of NBI heating with ECRH. The power threshold is found to increase with a decrease in density, almost independent of the launching order of the ECRH and NBI heating power. The pedestal density profiles in the H-mode discharges are measured. The particle outward convection is observed during the pump-out transient phase with ECRH. The negative density perturbation (pump-out) is observed to propagate much faster than the positive one caused by out-gassing. The core electron thermal transport reduction triggered by far off-axis ECRH switch-off is investigated. The coexistence of low frequency zonal flow (LFZF) and geodesic acoustic mode (GAM) is observed. The dependence of the intensities of LFZFs and GAMs on the safety factor and ECRH power is identified. The 3D spatial structures of plasma filaments are measured in the boundary plasma and large-scale structures along a magnetic field line analysed for the first time. The beta-induced Alfvén eigenmodes (BAEs), excited by large magnetic islands (m-BAE) and by energetic electrons (e-BAE), are observed. The results for the study of fuelling efficiency and penetration characteristics of supersonic molecular beam injection (SMBI) are described.

Yan, L. W.; Duan, X. R.; Ding, X. T.; Dong, J. Q.; Yang, Q. W.; Liu, Yi; Zou, X. L.; Liu, D. Q.; Xuan, W. M.; Chen, L. Y.; Rao, J.; Song, X. M.; Huang, Y.; Mao, W. C.; Wang, Q. M.; Li, Q.; Cao, Z.; Li, B.; Cao, J. Y.; Lei, G. J.; Zhang, J. H.; Li, X. D.; Chen, W.; Cheng, J.; Cui, C. H.; Cui, Z. Y.; Deng, Z. C.; Dong, Y. B.; Feng, B. B.; Gao, Q. D.; Han, X. Y.; Hong, W. Y.; Huang, M.; Ji, X. Q.; Kang, Z. H.; Kong, D. F.; Lan, T.; Li, G. S.; Li, H. J.; Li, Qing; Li, W.; Li, Y. G.; Liu, A. D.; Liu, Z. T.; Luo, C. W.; Mao, X. H.; Pan, Y. D.; Peng, J. F.; Shi, Z. B.; Song, S. D.; Song, X. Y.; Sun, H. J.; Wang, A. K.; Wang, M. X.; Wang, Y. Q.; Xiao, W. W.; Xie, Y. F.; Yao, L. H.; Yao, L. Y.; Yu, D. L.; Yuan, B. S.; Zhao, K. J.; Zhong, G. W.; Zhou, J.; Zhou, Y.; Yan, J. C.; Yu, C. X.; Pan, C. H.; Liu, Yong; HL-2A Team

2011-09-01

170

The experimental results and analysis of a borehole radar prototype  

NASA Astrophysics Data System (ADS)

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.

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

2012-04-01

171

Impact ejecta dynamics in an atmosphere - Experimental results and extrapolations  

NASA Technical Reports Server (NTRS)

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.

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

1982-01-01

172

Results of NASA's Energy Efficient Engine Program  

SciTech Connect

The major activity undertaken in the NASA Energy Efficient Engine Program has been completed. This paper reports on the progress made toward achieving the program goal of developing advanced technology to significantly reduce fuel consumption and operating costs of future subsonic transport-type propulsion systems. An additional goal was that the advanced concepts be compatible with future environmental regulations. Along with the results obtained, a brief overview of the design details of both the General Electric and Pratt and Whitney energy efficient engines and the overall program scope are presented. Overall, this program has been highly successful; the technology developed during its course is, and will continue to be, effectively employed in both current and future advance transport aircraft engine designs. 9 references.

Ciepluch, C.C.; Davis, D.Y.; Gray, D.E.

1987-12-01

173

EXPERIMENTAL RESULTS OF THE NEPHELINE PHASE III STUDY  

SciTech Connect

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 that those glasses that were found to contain nepheline after the centerline canister cooled (ccc) heat treatment generally had normalized release values that were greater than their quenched counterparts on a statistically significant basis. The current nepheline discriminator as implemented at the DWPF was shown to continue to work well in predicting nepheline prone glass compositions. A main objective of this study was to identify any compositional regions where conservatism in the current nepheline discriminator was preventing access to those regions that would otherwise be acceptable for DWPF processing by the PCCS models. Four glasses (based on the measured compositions) were identified through this study that met those criteria. However, a review of the individual compositions of these glasses revealed no clear trends that might indicate a driver for suppression of nepheline. Another objective of this study was to evaluate an alternative nepheline discriminator model developed using theory of crystallization in mineral and glass melts. Unfortunately this new model, in its current state, was unsuccessful in predicting nepheline crystallization in the glass compositions selected for this study. It is recommended that the data collected in this study be incorporated into the new model for further refinement.

Fox, K.; Edwards, T.

2009-11-09

174

New experimental sublimation energy measurements for some relevant astrophysical ices  

NASA Astrophysics Data System (ADS)

Context. The knowledge of the sublimation energy of ices allows us to better understand the dynamics between surfaces and atmospheres of different environments of astrophysical interest where ices are present. Aims: This work is intended to provide sublimation energy values for a set of pure ices (CO, CH4, CO2, N2, and NH3) using a new experimental procedure. The results were compared to some values obtained by other authors under different conditions and/or methods, to check the reliability of this new method. Methods: We used the frequency variation obtained from a quartz crystal microbalance to calculate the sublimation energy from the Polany-Wigner equation for the first time. Results: The results obtained are relevant since there are few previous values of sublimation energy reported on these molecules in these conditions of pressure and temperature, which are representative of astrophysical regions. These values are needed in models used to interpret dynamics of icy surfaces. In general, our results compare well to other ones obtained by different methods and complement those previously available.

Luna, R.; Satorre, M. Á.; Santonja, C.; Domingo, M.

2014-06-01

175

Alfven Wave Generation by a Rotating Magnetic Field Source: Theory, Modeling and Experimental Results  

NASA Astrophysics Data System (ADS)

Recent experiments conducted in the Large Plasma Device (LAPD) located at UCLA demonstrated efficient excitation of whistler and shear Alfven waves by a Rotating Magnetic Field (RMF) source. We present analytical theory, computational modeling and experimental results of the shear Alfven wave excitation by RMF source created by a phased orthogonal two-loop antenna in a plasma. An analytical theory and simulations using a three-dimensional cold two-fluid model of Alfven wave excitation were developed and compared with experiments. These comparisons show good agreement on linear shear Alfven wave properties, namely, spatio-temporal wave structure, dispersion relation, and the dependence of wave magnitude on the wave frequency. From the simulations it was found that the energy of the Alfven wave generated by the rotating magnetic field source is distributed among the kinetic energies of ions and electrons and the electromagnetic energy of the wave. The wave magnetic field power calculated from the experimental data and using a fluid model agrees within 1 percent. The RMF source is thus very efficient in generating shear Alfven waves. Work supported by ONR MURI grant.

Shao, X.; Karavaev, A. V.; Gumerov, N.; Sharma, A. S.; Papadopoulos, K.; Gekelman, W. N.; Wang, Y.; Vincena, S. T.; Pribyl, P.

2010-12-01

176

Alfven Wave Generation by a Rotating Magnetic Field Source: Theory, Modeling and Experimental Results  

NASA Astrophysics Data System (ADS)

Recent experiments conducted in the Large Plasma Device (LAPD) located at UCLA demonstrated efficient excitation of whistler and shear Alfven waves by a Rotating Magnetic Field (RMF) source. We present analytical theory, computational modeling and experimental results of the shear Alfven wave excitation by RMF source created by a phased orthogonal two-loop antenna in a plasma. An analytical theory and simulations using a three-dimensional cold two-fluid model of Alfven wave excitation were developed and compared with experiments. These comparisons show good agreement on linear shear Alfven wave properties, namely, spatio-temporal wave structure, dispersion relation, and the dependence of wave magnitude on the wave frequency. From the simulations it was found that the energy of the Alfven wave generated by the rotating magnetic field source is distributed among the kinetic energies of ions and electrons and the electromagnetic energy of the wave. The wave magnetic field power calculated from the experimental data and using a fluid model agrees within ˜1 percent. The RMF source is thus very efficient in generating shear Alfven waves. Work supported by ONR MURI grant.

Sharma, A. S.; Karavaev, A. V.; Gumerov, N.; Shao, X.; Papadopoulos, K.; Gekelman, W.; Wang, Y.; Vincena, S.; Pribyl, P.

2010-11-01

177

First experimental results of the BNL inverse free electron laser accelerator  

SciTech Connect

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.

Steenbergen, A. van; Gallardo, J.; Babzien, M.; Skaritka, J.; Wang, X.J. [Brookhaven National Lab., Upton, NY (United States); Sandweiss, J. [Yale Univ., New Haven, CT (United States). Physics Dept.; Fang, J.M. [Columbia Univ., New York, NY (United States). Dept. of Applied Physics; Qiu, X. [State Univ. of New York, Stony Brook, NY (United States). Physics Dept.

1996-10-01

178

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

NASA Astrophysics Data System (ADS)

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.

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

2005-04-01

179

The mapping of electronic energy distributions using experimental electron density.  

PubMed

It is demonstrated that the approximate kinetic energy density calculated using the second-order gradient expansion with parameters of the multipole model fitted to experimental structure factors reproduces the main features of this quantity in a molecular or crystal position space. The use of the local virial theorem provides an appropriate derivation of approximate potential energy density and electronic energy density from the experimental (model) electron density and its derivatives. Consideration of these functions is not restricted by the critical points in the electron density and provides a comprehensive characterization of bonding in molecules and crystals. PMID:12149553

Tsirelson, Vladimir G

2002-08-01

180

Deuteron induced reactions on Ho and La: Experimental excitation functions and comparison with code results  

NASA Astrophysics Data System (ADS)

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.

Hermanne, A.; Adam-Rebeles, R.; Tarkanyi, F.; Takacs, S.; Csikai, J.; Takacs, M. P.; Ignatyuk, A.

2013-09-01

181

An Experimental Study on Thermal Energy Storage Based Reverse Cycle Defrosting Method Using Subcooling Energy of Refrigerant for Air Source Heat Pump: Characteristics of Thermal Energy Storage Operation  

Microsoft Academic Search

the introduction introduction of the the system of thermal energy storage torage (TES) based reverse cycle defrosting method using sub-cooling energy of refrigerant for air Source heat eat p pump (ASHP) is given firstly. And And then the the characteristic of TES TES using sub-cooling energy of refrigerant in in heating is experimentally researched. The results results show that that

Dong Jiankai; Qu Minglu; Jiang Yiqiang; Yao Yang; Deng Shiming; Wang Honglei

2011-01-01

182

Comparison between Theoretical Calculation and Experimental Results of Excitation Functions for Production of Relevant Biomedical Radionuclides  

NASA Astrophysics Data System (ADS)

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.

Menapace, E.; Birattari, C.; Bonardi, M. L.; Groppi, F.; Morzenti, S.; Zona, C.

2005-05-01

183

A comparison of PIC simulation and experimental results in a capacitive RF discharge  

SciTech Connect

Simulation results for PDP1, a 1d3v bounded particle-in-cell code, are compared to recently published experimental results over a pressure range of 10-100 mTorr and 100-1000 V applied RF voltage in a symmetric, parallel plate, argon discharge. The authors show that where similar results are obtained, the simulation allows insight into plasma parameters which are not experimentally accessible, such as details of the electron power sources and losses.

Mirrashidi, P.; Wood, B.P.; Vahedi, V. [Univ. of California, Berkeley, CA (United States)] [and others

1992-12-01

184

Ply drop-off effects in CFRP\\/honeycomb sandwich panels—experimental results  

Microsoft Academic Search

The results of a combined experimental and theoretical investigation of local bending effects induced by ply drop-off in CFRP\\/honeycomb sandwich panels are presented. The objective of the investigation was to validate a simple model for engineering analysis of sandwich panels with tapered face laminates presented in a previous paper. The experimental investigation was conducted by using electronic speckle pattern interferometry

O. T. Thomson; W. Rits; D. C. G. Eaton; O. Dupont; P. Queekers

1996-01-01

185

Simulation and Experimental Results of a 0.15µm Independent Double Gated CMOS Transistor  

Microsoft Academic Search

Independent double gated transistors give better control of the channel and dynamic tradeoff between power and performance. An independent double gated (IDG) FlexFET transistor is simulated using the Silvaco Atlas tool and the results are then compared with the data obtained from experimental devices manufactured by American Semiconductor Inc. (ASI). A reasonable correlation between the simulations and the experimental devices

V. Vasireddy; S. Parke

2010-01-01

186

Initial Diagnostics and First Experimental Results of the Pulsed High Density (PHD) FRC Experiment*  

NASA Astrophysics Data System (ADS)

The source region for the Pulsed High Density Experiment (PHDX) has been constructed, and Field-Reversed Configuration (FRC) plasmas are being produced. The several diagnostic systems include and axial array of 20 pairs of magnetic probes and flux loops, and a 64 channel array optical measurement system for visible bremstrahlung tomography. The tomographic system will be capable of reconstructing the plasma shape and mode structure, and will incorporate information from end-on imaging for improved resolution. This array consists of collimator, optical fiber, optical filter (?=520 nm, FWHM= 1 to 10 nm), and Photomultiplier Tube (PMT). The tomographic system and magnetic loop array will be used to investigate the equilibrium and tilt stability of FRCs at high s/E (>3) where s is the ion collisionless skin depth and E is the plasma elongation. The separatrix radius (rs) of FRC plasma is determined by the excluded flux measurement, and it is found that rs=0.04-0.05 m (rs/rw=0.16-0.2) just after the RMF current drive start-up. The time sequence of separatrix shape relatively agrees with the result of that estimated from the line-integrated radiation intensity at different axial positions. We will present the result of both simulation and experimental results from measured FRC plasmas as well as future plans. *Research funded by the DOE Office of Fusion Energy Sciences

Gota, Hiroshi

2005-10-01

187

Experimental investigation on spectral-energy efficiency of femtosecond laser ablation of metals  

SciTech Connect

Results of investigation on spectral-energy thresholds, rates, and mass flow rates of laser ablation of structural materials (Cu, Ti, Zr, Nb, Mo) of high-energy photonics are presented. The data were obtained by means of an experimental diagnostic module developed for study of multifactor interaction processes between UV-near IR femtosecond laser pulse radiation and condensed media in vacuum.

Loktionov, E. Yu., E-mail: stcpe@bmstu.ru [Bauman Moscow State Technical University (Russian Federation); Ovchinnikov, A. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation); Protasov, Yu. Yu. [Bauman Moscow State Technical University (Russian Federation); Sitnikov, D. S. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

2011-12-15

188

Summary of the experimental results of the loss-of-coolant accident tests: LOFT  

Microsoft Academic Search

Key results relating to emergency core cooling (ECC) behavior during the LOFT nonnuclear tests are discussed. LOFT test results are compared with results from counterpart experiments performed in the Semiscale facility to evaluate the scaling. Experimental results are also compared with pretest analytical model predictions made with the RELAP\\/MOD5 computer code to evaluate the capability of the analytical model. System

1978-01-01

189

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

NASA Astrophysics Data System (ADS)

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.

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

190

NN Implies pi D and NN Implies NN pi ; a Review of Experimental Results.  

National Technical Information Service (NTIS)

As a result of recent precision measurements, detailed experimental characteristics of the pp implies d pi reaction are now beginning to emerge. Most experiments have involved measurements of either the (unpolarized) differential cross section or the pola...

G. Jones

1981-01-01

191

Experimental Results for Temporally Overlapping Pulses from Quantel EverGreen 200 Laser  

NASA Technical Reports Server (NTRS)

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.

Watkins, A. Neal

2013-01-01

192

Comparative study between computational and experimental results for binary rarefied gas flows through long microchannels  

Microsoft Academic Search

A comparative study between computational and experimental results for pressure-driven binary gas flows through long microchannels\\u000a is performed. The theoretical formulation is based on the McCormack kinetic model and the computational results are valid\\u000a in the whole range of the Knudsen number. Diffusion effects are taken into consideration. The experimental work is based on\\u000a the Constant Volume Method, and the

Lajos Szalmas; Jeerasak Pitakarnnop; Sandrine Geoffroy; Stephane Colin; Dimitris Valougeorgis

2010-01-01

193

Hyperfine-structure studies of Zr ii: Experimental and relativistic configuration-interaction results  

NASA Astrophysics Data System (ADS)

We report an experimental and theoretical study of the hyperfine structure (hfs) in various metastable levels in 91Zr ii. Hyperfine structures in 11 levels arising from the 4d3 and 4d25s configurations were measured using the laser-rf double-resonance method in a collinear laser-ion-beam geometry. The hfs A and B constants were measured to a precision of 4 and 11 kHz, respectively. Less precise values for hfs constants for nine upper levels in the 4d25p configuration were derived from optical spectra. Theoretically, the A and B constants for the metastable levels having J=0.5 and 1.5 were calculated using a relativistic configuration-interaction (RCI) approach. The final many-body wave function produced energy gaps between the five J=0.5 levels which differ from experiment by an average of 0.050 eV, whereas the corresponding value for the ten J=1.5 levels is 0.087 eV. For the two J=0.5 levels measured and calculated, the average error in A is 31.8%. For the three J=1.5 levels, the situation is better, with the average error in A being 9.2%. For comparison, the average errors in A using independent-particle Dirac-Fock (DF) wave functions were 88% and 136% for J=0.5 and 1.5, respectively. In all cases, the many-body (RCI) result represents a vast improvement from the DF result for the A values. The value for the electric-quadrupole moment of 91Zr obtained from a comparison of the experimental B values and theoretical matrix elements is 0.257(0.013) b. In addition, the calculations confirm a previous report that the level at 17 614.00 cm-1 reported in Moore's Atomic Energy Levels, Vol. II (U.S. Government Printing Office, Washington, D.C., 1971) is spurious.

Young, L.; Kurtz, C. A.; Beck, Donald R.; Datta, Debasis

1993-07-01

194

I camini solari dell'edificio bioclimatico dell'ENEA di Ispra: Primi risultati sperimentali. (ENEA Ispra (Italy) bioclimatic building solar chimneys. First experimental results).  

National Technical Information Service (NTIS)

This paper reports and comments on the experimental results obtained in a research program survey aimed at providing a design and performance technical data base characterizing the solar chimneys of the ENEA (Italian Commission for Alternative Energy Sour...

S. Fumagalli G. Contadini G. Leonardi E. Ferrari E. Costa

1989-01-01

195

Comparison of experimental coupled helicopter rotor/body stability results with a simple analytical model  

NASA Technical Reports Server (NTRS)

The results of an analytical study aimed at predicting the aeromechanical stability of a helicopter in ground resonance, with the inclusion of aerodynamic forces are presented. The theoretical results are found to be in good agreement with the experimental results, available in literature, indicating that the coupled rotor/fuselage system can be represented by a reasonably simple mathematical model.

Friedmann, P. P.; Venkatesan, C.

1988-01-01

196

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

NASA Technical Reports Server (NTRS)

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.

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

1994-01-01

197

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

NASA Technical Reports Server (NTRS)

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.

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

1993-01-01

198

The first experimental results from x-ray imaging crystal spectrometer for KSTAR  

SciTech Connect

The x-ray imaging crystal spectrometer (XICS) for the Korea Superconducting Tokamak Advanced Research has been first applied for the experimental campaign in 2009. The XICS was designed to provide measurements of the profiles of the ion and electron temperatures from the heliumlike argon (Ar XVII) spectra. The basic functions of the XICS are properly working although some satellites lines are not well matched with the expected theoretical values. The initial experimental results from the XICS are briefly described.

Lee, S. G.; Bak, J. G. [National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Nam, U. W. [Korea Astronomy and Space Science Institute, Daejeon 305-348 (Korea, Republic of); Moon, M. K. [Korea Atomic Energy Research Institute, Daejeon 305-353 (Korea, Republic of); Shi, Y. [Institute of Plasma Physics, Chinese Academy of Science, Hefei 230031 (China); Bitter, M.; Hill, K. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-10-15

199

Analysis of the experimental results of the superluminescent fiber laser sources designed for fiber optic sensors  

NASA Astrophysics Data System (ADS)

We present a simple analysis and comparison between the theoretical and experimental results, in an erbium-doped optical fiber operating in the superluminescent regime. Experimental results for different pumping power levels and fiber length shows, that the theoretical results given for the numerical model could render useful information for predicting parameters such as total output power. These types of sources could have direct application in wavelength multiplexed arrangements of fiber sensors, fiber gyroscopes or in general, in any sensors in which a broad wavelength and stable light source is required.

Pinzón-Escobar, E. F.; Sandoval-Romero, G. E.

2012-09-01

200

Experimental Results with the KVH C-100 Fluxgate Compass in Mobile Robots  

Microsoft Academic Search

This paper presents a discussion on the use of ele c- tronic compasses in mobile robots. Different error sources are considered, and solutions are proposed to correct these errors. Experimental results show the effec- tiveness of some of the error reduction measures. The results also show what performance can be expected from a well-calibrated compass system. The overall most important

Lauro Ojeda; Johann Borenstein

2000-01-01

201

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

Microsoft Academic Search

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

Oleksandr Sinitsyn; Gregory Nusinovich; Thomas Jr. Antonsen

2010-01-01

202

Result-driven strategies for protein identification and quantitation--a way to optimize experimental design and derive reliable results.  

PubMed

Uni- or multidimensional microcapillary liquid chromatography (microLC) matrix-assisted laser desorption/ionization (MALDI) tandem mass spectrometry (MS/MS) approaches have gained significant attention for quantifying and identifying proteins in complex biological samples. The off-line coupling of microLC with MS quantitation and MS/MS identification methods makes new result-dependent workflows possible. A relational database is used to store the results from multiple high performance liquid chromatography runs, including information about MALDI plate positions, and both peptide and protein quantitations, and identifications. Unlike electrospray methodology, where all the decisions about which peptide to fragment, must be made during peptide fractionations, in the MALDI experiments the samples are effectively "frozen in time". Therefore, additional MS and MS/MS spectra can be acquired, to promote more accurate quantitation or additional identifications until reliable results are derived that meet experimental design criteria. In the case of what can be designated the expression-dependent workflow, quantitation can be detached from identification and only peak pairs with biological relevant expression changes can be selected for further MS/MS analyses. Alternatively, additional MS/MS data can be acquired to confirm tentative peptide mass fingerprint hits in what is designated a search result-dependent workflow. In the MS data-dependent workflow, the goal is to collect as many meaningful spectra as possible by judiciously adjusting the acquisition parameters based on characteristics of the parent masses. This level of sophistication requires the development of innovative algorithms for these three result-dependent workflows that make MS and MS/MS analysis more efficient and also add confidence to experimental results. PMID:14760720

Graber, Armin; Juhasz, Peter S; Khainovski, Nikita; Parker, Kenneth C; Patterson, Dale H; Martin, Stephen A

2004-02-01

203

Experimental and computational analysis on guide vane losses of impulse turbine for wave energy conversion  

Microsoft Academic Search

This paper deals with the detailed flow analysis of impulse turbine with experimental and computed results for wave energy power conversion. Initially, several turbulence models have been used in two-dimensional (2-D) computational fluid dynamic (CFD) analysis to find a suitable model for this kind of slow speed unconventional turbine. Experiments have been conducted to validate the CFD results and also

A. Thakker; T. S. Dhanasekaran

2005-01-01

204

Broadband permeability measurement method for ferrites at any magnetization state: Experimental results  

NASA Astrophysics Data System (ADS)

This paper describes the experimental results obtained by a broadband permeability measurement method based on the full-wave electromagnetic (EM) analysis of a non-reciprocal transmission line. The method offers a new experimental tool for measuring the broadband dynamic behavior of ferrites whatever their magnetization state. The methodology and experimental setup are presented with the aim of extracting both the permittivity and the two components (diagonal ? and off-diagonal ?) of the permeability tensor. Experimental data on commercial ferrites set in different magnetization states are presented and discussed. Furthermore, this method opens perspectives for the determination of other useful magnetic parameters such as resonance linewidth ?H. This quantity can be then measured at different frequencies, where conventional resonant methods give a value at a fixed frequency.

Chevalier, A.; Cortes, J.; Lezaca, J.; Queffelec, P.

2013-11-01

205

Interaction of imidazolinone herbicides with soil humic acids. Experimental results and molecular modeling.  

PubMed

Adsorption and desorption isotherms of the herbicides imazapyr, imazethapyr and imazaquin on a soil humic acid have been performed at pH 2.8 and 4.0 (below and above the pKa of the herbicides). At both pH, adsorption increased according to the lipophilic character of the molecules (imazapyr < imazethapyr < imazaquin). The extent of adsorption was higher at pH 2.8 than at pH 4.0 because of the partial ionization of the carboxylic groups of both herbicides and humic acids at increasing pH. Desorption of imazapyr and imazethapyr was nearly complete at pH 4 and higher than 60% at pH 2.8 while desorption of imazaquin was 45 and 8% at pH 4 and 2.8, respectively. No differences between adsorption isotherms at 10 degrees C and 25 degrees C were observed a pH 4.0 indicating that adsorption involved very weak bonds while at pH 2.8, adsorption was higher at 10 degrees C than at 25 degrees C indicating an exothermic process. The isosteric enthalpy of adsorption of each herbicide was low (about -1 kJoule mole(-1)) suggesting that low energetic bonds were involved. Adsorption on different humic acids has indicated that for each herbicide, the extent of adsorption expressed as Kd was correlated with the amount of carboxylic and aromatic groups of humic acids suggesting that hydrogen bonding and/or charge-transfer complexes formation could take place. Molecular modeling and geometry optimization of humic acid and soil organic matter (SOM) herbicide complexes were also performed. The results obtained with this theoretical approach gave a consistent chemical interpretation of the experimental results. To the best of our knowledge this is the first report to contribute to a better understanding of site-specific bonding of herbicides in SOM complexes by nanochemical modeling and distinct energy descriptors. PMID:11409493

Nègre, M; Schulten, H R; Gennari, M; Vindrola, D

2001-03-01

206

Armature reaction effects on a high temperature superconducting field winding of an synchronous machine: experimental results  

NASA Astrophysics Data System (ADS)

This paper presents experimental results from the Superwind laboratory setup. Particular focus in the paper has been placed on describing and quantifying the influence of armature reaction on performance of the HTS filed winding. Presented experimental results have confirmed the HTS field winding sensitivity to both armature reaction intensity and angular position with respect to the HTS coils. Furthermore, the characterization of the HTS field winding has been correlated to the electromagnetic torque of the machine where the maximal Ic reduction of 21% has been observed for the maximum torque.

Mijatovic, Nenad; Jensen, Bogi Bech

2014-05-01

207

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

NASA Astrophysics Data System (ADS)

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.

Coppersmith, Susan N.

2013-03-01

208

An Experimental and Theoretical High Energy Physics Program  

SciTech Connect

The Purdue High Energy Physics Group conducts research in experimental and theoretical elementary particle physics and experimental high energy astrophysics. Our goals, which we share with high energy physics colleagues around the world, are to understand at the most fundamental level the nature of matter, energy, space and time, and in order to explain the birth, evolution and fate of the Universe. The experiments in which we are currently involved are: CDF, CLEO-c, CMS, LSST, and VERITAS. We have been instrumental in establishing two major in-house facilities: The Purdue Particle Physics Microstructure Detector Facility (P3MD) in 1995 and the CMS Tier-2 center in 2005. The research efforts of the theory group span phenomenological and theoretical aspects of the Standard Model as well as many of its possible extensions. Recent work includes phenomenological consequences of supersymmetric models, string theory and applications of gauge/gravity duality, the cosmological implications of massive gravitons, and the physics of extra dimensions.

Shipsey, Ian

2012-07-31

209

Application of an Unstructured Grid Navier-Stokes Solver to a Generic Helicopter Boby: Comparison of Unstructured Grid Results with Structured Grid Results and Experimental Results  

NASA Technical Reports Server (NTRS)

An unstructured-grid Navier-Stokes solver was used to predict the surface pressure distribution, the off-body flow field, the surface flow pattern, and integrated lift and drag coefficients on the ROBIN configuration (a generic helicopter) without a rotor at four angles of attack. The results are compared to those predicted by two structured- grid Navier-Stokes solvers and to experimental surface pressure distributions. The surface pressure distributions from the unstructured-grid Navier-Stokes solver are in good agreement with the results from the structured-grid Navier-Stokes solvers. Agreement with the experimental pressure coefficients is good over the forward portion of the body. However, agreement is poor on the lower portion of the mid-section of the body. Comparison of the predicted surface flow patterns showed similar regions of separated flow. Predicted lift and drag coefficients were in fair agreement with each other.

Mineck, Raymond E.

1999-01-01

210

Experimental results on adaptive output feedback control using a laboratory model helicopter  

Microsoft Academic Search

Experimental results are presented that illustrate a recently developed method for adaptive output feedback control. The method permits adaptation to both parametric uncertainty and unmodeled dynamics, and incorporates a novel approach that permits adaptation under known actuator characteristics including actuator dynamics and saturation. Only knowledge of the relative degree of the controlled system within the bandwidth of the control design

Ali T. Kutay; Anthony J. Calise; Moshe Idan; Naira Hovakimyan

2005-01-01

211

Photon detection with cooled avalanche photodiodes: Theory and preliminary experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1985-01-01

212

Experimental and theoretical results of stress relaxations in a model of earthquake dynamics  

Microsoft Academic Search

We report on experimental and theoretical results on the dynamical behavior of propagating solitary relaxations in a model system for earthquake-like dynamics. In the experiments, a continuous elastic medium is sheared at very slow rate in between two coaxial cylinders. Solitary propagating relaxations travel at speeds that are proportional to the driving speed, though ~ 103 times faster, and inversely

J. Galeano; P. Español; M. A. Rubio

2000-01-01

213

Experimental Results of a Small Water-Augmented Air-Jet.  

National Technical Information Service (NTIS)

Experimental results from a small static water-augmented air-jet (46 gas horsepower maximum) are presented and correlated with theory. The data consists of thrust measurements as a function of mass-flow ratio for three spray station configurations and two...

A. E. Ford R. K. Muench

1969-01-01

214

Supplement to the Report on the Results Achieved with Seas' Experimental Mill.  

National Technical Information Service (NTIS)

Results achieved with an experimental windmill are elaborated on: greatest efficiency of the mill was obtained at a wingtip velocity of 38 m/x; effects caused by wind pressure should not exceed 800 kg/sq cm in any part of the wing or tower, and effects ca...

J. Juul

1974-01-01

215

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

ERIC Educational Resources Information Center

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.)

Gates, Joshua

2009-01-01

216

Teetered, Tip-Controlled Rotor: Preliminary Test Results from MOD-0 100-KW Experimental Wind Turbine.  

National Technical Information Service (NTIS)

A series of tests is currently being conducted using the DOE/NASA 100 kW Experimental Wind Turbine with a two-bladed, teetered rotor with 30% span tip control. Preliminary evaluation test results indicate that the teetered rotor significantly decreases lo...

J. C. Glasgow D. R. Miller

1980-01-01

217

Experimental results from FLEXnav: an expert rule-based dead-reckoning system for Mars rovers  

Microsoft Academic Search

This paper presents a proprioceptive position estimation system (PPE) with inertial measurement unit (IMU) uses fuzzy logic operations in conjunction with the expert rules for finer gradation called fuzzy logic expert navigation (FLEXnav) PPE system. The detailed experimental results obtained with our FLEXnav system integrated with our Mars rover clone Fluffy and operating in a Mars-like environment. The paper also

Lauro Ojeda; Giulio Reina; Johann Borenstein

2004-01-01

218

[Late results of different methods of surgical treatment of experimental retropatellar cartilage defects].  

PubMed

The result of the experimental studies encouraged us to treat our patients with chondro-malacia patellae not only by superficially rasping the damaged cartilage, but also by drilling several holes down to the subchondral layer. This allows a type of tissue repair by connective tissue. In addition we prefer a section of the retinacula and an anteposition of the patella ligament. PMID:659234

Kinzl, L; von Mathei, F; Burri, C

1978-05-01

219

Results of experimental investigations of the mechanical characteristics of a sandy soil under static loadings  

Microsoft Academic Search

The article gives the results of experimental investigations of the compressibility of a sandy soil of different moisture content under static loads with an intensity up to ~ 1 = 400-600 kg\\/cm 2. The method is discussed and the cormtruction of a pickup for the measurement of such stresses is described. It is shown that the trajectories of the loading

Yu. M. Glukhov; Yu. V. Kulinich; G. V. Rykov

1978-01-01

220

Fuel cell system integration into a heavy-duty hybrid vehicle: preliminary experimental results  

Microsoft Academic Search

This paper is the second paper dealing with the evaluation of different power sources and hybridization strategies in a heavy-duty vehicle. It focuses on the physical integration of a fuel cell system (FCS) into the vehicle as well as the preliminary experimental results obtained with the FCS coupled to batteries. The vehicle considered here is a mobile research platform (ECCE)

J. Mulot; F. Harel; S. Begot; D. Hissel; I. Rodel; S. Boblet; M. Amiet

2010-01-01

221

Comparison of Computational and Experimental Aerodynamics: Results for a WMU Solar Car Model  

Microsoft Academic Search

Three-dimensional numerical simulations using FLUENT [1] were performed to model the airflow over the Sunseeker, an award-winning solar car that was designed and built at Western Michigan University. Converged numerical solutions on three different grids are reported and compared with the available experimental data, which include the lift and the drag coefficients. Also reported are the results obtained by using

Yang Yang; William W. Liou

2011-01-01

222

IEEE 802.11 b performance evaluation: convergence of theoretical, simulation and experimental results  

Microsoft Academic Search

The work presents the analysis of the evaluation of the maximum goodput achievable in a IEEE 802.11 b basic set service (BSS) performed by means of theoretical, simulative and experimental approaches. With respect to previous works on this topic, the presented study focuses on the comparison of the results obtained using the different approaches, highlighting their convergence in the simple

R. G. Oarroppo; Stefano Giordano; S. Lucetti

2004-01-01

223

TRANSCRITICAL CO2 MOBILE HEAT PUMP AND A\\/C SYSTEM EXPERIMENTAL AND MODEL RESULTS  

Microsoft Academic Search

This article presents the results of the experimental runs of a prototype of R744 (CO2) refrigeration system operating in a both air conditioning and heat pump mode when heat rejection is done in supercritical region. The prototype system is sized for a compact car. Data presented are in the limited range of operation. Further optimization and extension of operating range

C. W. Bullard; J. M. Yin; P. S. Hrnjak

224

Comparison of simulated structural deformation with experimental results after Wingspan stenting.  

PubMed

Objectives: Biomechanical stress distribution correlates with the biological responses after stenting. Computational analyses have contributed to the optimization of stent geometry. In particular, structural analysis based on pre-operative angiography can be used to predict the stent-artery interaction before endovascular treatments. However, the simulated results need to be validated. In this report, we compared the simulated arterial structure with post-operative images after an intracranial Wingspan stent. Methods: A Wingspan stent was deployed at a slightly curved ascending pharyngeal artery (APA) in the swine. Using a finite element method (FEM), the configuration after stenting was simulated and quantitatively compared with post-procedural 3D angiography. Results: The finite element analysis demonstrated arterial straightening after stenting. The simulated images were similar to the experimental results with respect to the curvature index of the center line and the cross-sectional areas. Conclusion: We assessed the simulated structural deformation after Wingspan stenting, by comparison with experimental results. PMID:24620967

Fujimoto, Motoaki; Shobayashi, Yasuhiro; Tateshima, Satoshi; Sudo, Ryo; Tanishita, Kazuo; Viñuela, Fernando

2014-08-01

225

Review on optical constants of Titan aerosols: Experimental results and modeling/observational data  

NASA Astrophysics Data System (ADS)

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 available. Therefore it would be very useful to get more laboratory data and especially from Tran et al (2013), Mahjoub et al. (2012) and Imanaka et al. (2012) samples in these spectral regions since their refractive indexes match observational and theoretical data in other spectral ranges. This presentation will critically summarize these recent results and present detailled constraints on the optical constants Titan's aerosols. In addition, specific lacks of data will be highlighted as well as some possible investigations to be carried out to fill these gaps. References: Cable, M. L., et al., 2012. Titan Tholins: Simulating Titan Organic Chemistry in the Cassini-Huygens Era. Chemical Reviews. 112, 1882-1909. Imanaka, H., et al., 2012. Optical constants of Titan tholins at mid-infrared wavelengths (2.5-25 µm) and the possible chemical nature of Titan's haze particles. Icarus. 218, 247-261. Khare, B. N., et al., 1984. Optical-Constants of Organic Tholins Produced in a Simulated Titanian Atmosphere - from Soft-X-Ray to Microwave-Frequencies. Icarus. 60, 127-137. Kim, S. J., Courtin, R., 2013. Spectral characteristics of the Titanian haze at 1?5 micron from Cassini/VIMS solar occultation data. Astronomy & Astrophysics. 557, L6. Mahjoub, A., et al., 2012. Influence of methane concentration on the optical indices of Titan's aerosols analogues. Icarus. 221, 670-677. Raulin, F., et al., 2012. Prebiotic-like chemistry on Titan. Chemical Society Reviews. 41, 5380-5393. Sagan, C., Khare, B. N., 1979. Tholins - Organic-Chemistry of Inter-Stellar Grains and Gas. Nature. 277, 102-107. Tran, B. N., et al., 2003. Simulation of Titan haze formation using a photochemical flow reactor - The optical constants of the polymer. Icarus. 165, 379-390. Acknowledgements: We acknowledge support from the French Space Agency (CNES) and the European Space Agency (ESA).

Brassé, Coralie; Muñoz, Olga; Coll, Patrice; Raulin, François

2014-05-01

226

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

SciTech Connect

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.

Cherne, Frank J [Los Alamos National Laboratory; Jensen, Brian J [Los Alamos National Laboratory; Rigg, Paulo A [Los Alamos National Laboratory; Elkin, Vyacheslav M [VNIITF

2009-01-01

227

Phase Partitioning of Common Alcohols With BTEX Compounds in Water: Comparison Between Modeling and Experimental Results  

NASA Astrophysics Data System (ADS)

This study compares the modeling and experimental results on the equilibrium phase partitioning behavior of three common alcohols (ethanol, isopropanol, and methanol) in a two-phase system consisting of water and a BTEX compound. A previously developed computer program is used to generate ternary phase diagrams for each alcohol-water-NAPL mixture combination, where the required activity coefficients are estimated using the UNIFAC model. A set of laboratory experiments is conducted to determine the maximum single-phase water content for every alcohol-water-NAPL mixture combination considered in this study, where the initial volume composition is 85 percent alcohol and 15 percent NAPL. Comparison of experimental results against UNIFAC- derived modeling results shows good agreement for mixtures containing ethanol and methanol, but relatively poor agreement for mixtures containing isopropanol.

Lee, K. Y.

2007-12-01

228

Modeling the Fracturing of Rock by Fluid Injection - Comparison of Numerical and Experimental Results  

NASA Astrophysics Data System (ADS)

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 observations, including fracture evolution, excellent agreement of the entire load-unload stress strain behavior, and applicable to both drained and un-drained conditions. Bibliography: M.A. Biot. General Theory of Three- Dimensional Consolidation. Journal of Applied Physics, 12:155 - 164, February 1941. P.A. Vermeer and R. de Borst. Non- associated Plasticity For Soils, Concrete and Rock. Heron, 29(37), 1984. S. Stanchits, S. Mayr, S. Shapiro and G. Dresen. Fracturing of Porous Rock Induced by Fluid Injection. Tectonophysics, (503):129-145, 2011.

Heinze, Thomas; Galvan, Boris; Miller, Stephen

2013-04-01

229

Experimental and simulated XPS depth profiles of low-energy high dose nitrogen implanted into aluminium  

Microsoft Academic Search

In the paper the XPS measurements of aluminium samples implanted with low energy, high dose nitrogen ions are presented. The experimental results are compared with those obtained from a Monte-Carlo computer simulation. The influence of collisions atomic mixing and ion-bombardment-induced segregation on the distortion of the measured depth profile of implanted ions is discussed.

JL Sullivan; Z Wronski; SO Saied; J Sielanko

1995-01-01

230

Experimental investigation of the collapse modes and energy absorption characteristics of composite tubes  

Microsoft Academic Search

This paper describes the results of an experimental investigation of tubes made of different composite materials. They are structural components used in the aerospace and automotive industries, which are able to absorb large amounts of impact energy while collapsing progressively in a controlled manner. Because of the complex fracture mechanisms, several different collapse modes are obtained. From the tests, it

Chiara Bisagni

2009-01-01

231

Automated modular high energy evaluation system for experimental thyristor devices.  

PubMed

A high energy, modular, completely automated test bed with integrated data acquisition and characterization systems was successfully designed in order to perform both safe operating area as well as very high volume reliability testing on experimental silicon carbide Super Gate Turn Off (SGTO) thyristors. Although the system follows a modular design philosophy, with each functional block acting as a peripheral to a main control module and can be adapted to arbitrary power and pulse width levels, for the specific SGTO devices initially evaluated it was configured to have the device discharge variable current levels of up to 6 kA into a 0.5 ? resistive load with a relatively square pulse fixed at 100 ?s full width at half maximum delivering energy levels up to 1.8 kJ to the load. PMID:24182164

Lacouture, Shelby; Lawson, Kevin; Bayne, Stephen; Giesselmann, Michael; Scozzie, Charles J; O'Brien, Heather; Ogunniyi, Aderinto A

2013-10-01

232

Experimental studies of systematic multiple-energy operation at HIMAC synchrotron  

NASA Astrophysics Data System (ADS)

Multiple-energy synchrotron operation providing carbon-ion beams with various energies has been used for scanned particle therapy at NIRS. An energy range from 430 to 56 MeV/u and about 200 steps within this range are required to vary the Bragg peak position for effective treatment. The treatment also demands the slow extraction of beam with highly reliable properties, such as spill, position and size, for all energies. We propose an approach to generating multiple-energy operation meeting these requirements within a short time. In this approach, the device settings at most energy steps are determined without manual adjustments by using systematic parameter tuning depending on the beam energy. Experimental verification was carried out at the HIMAC synchrotron, and its results proved that this approach can greatly reduce the adjustment period.

Mizushima, K.; Katagiri, K.; Iwata, Y.; Furukawa, T.; Fujimoto, T.; Sato, S.; Hara, Y.; Shirai, T.; Noda, K.

2014-07-01

233

Experimental Results for Slow-speed Timing Characterization of High-speed Pipelined Datapaths  

Microsoft Academic Search

This article presents experimental results for a clock-timing methodology that allows timing characterization and testing\\u000a of high-speed pipelined datapaths using slow-speed testers. The technique uses a clock-timing circuit to control the data\\u000a flow in the pipeline in the test mode. Test results show that the design provides an average timing resolution of 52.9 ps\\u000a in 0.18 ?m CMOS technology. Results also demonstrate

Muhammad Nummer; Manoj Sachdev

2011-01-01

234

Au L? x-rays induced by photons from 241Am: Comparison of experimental results and the predictions of PENELOPE.  

PubMed

The results of experiments performed, measuring the L? x-rays emitted by Au due to excitation by photons of various energies from an (241)Am sample at forward-scattered angles in the range 0° to 65°, are compared to the predictions of the Monte Carlo code, PENELOPE. The experimental data are in good agreement with the predictions of the program. A comparison of the angular distributions of the probability densities (as predicted by the program) related to the Au L? and L? x-rays suggests that PENELOPE does not simulate the phenomena described by Flügge et al. (1972). PMID:21890370

Gonzales, D; Requena, S; Williams, S

2012-01-01

235

A Liquid Xenon Positron Emission Tomograph for small animal imaging: First experimental results of a prototype cell  

NASA Astrophysics Data System (ADS)

A detector using Liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Its specific design aims at taking full advantage of the LXe scintillation properties. This paper reports on energy, time and spatial resolution capabilities of the first LXe prototype module equipped with a Position Sensitive Photo Multiplier Tube (PSPMT) operating in the VUV range (178 nm) and at 165 K. The experimental results show that such an LXe PET configuration might be a promising solution insensitive to any parallax effect.

Gallin-Martel, M.-L.; Gallin-Martel, L.; Grondin, Y.; Rossetto, O.; Collot, J.; Grondin, D.; Jan, S.; Martin, Ph.; Mayet, F.; Petit, P.; Vezzu, F.

2009-02-01

236

Experimental results of the variable speed, direct drive multipole synchronous wind turbine TWT1650  

NASA Astrophysics Data System (ADS)

This article presents details of the new variable speed multipole large wind turbine TWT1650 designed by the M. Torres group and summarizes some experimental results of the control system. After several years of multidisciplinary research the first prototype TWT1650 began to work at Cabanillas Wind Farm (Spain) in August 2001. Since then a large number of operational data have been collected and used to improve the behaviour of the machine. The design and controller tuning have been accomplished using advanced QFT (quantitative feedback theory) robust control strategies and have been optimized based on analysis of that information. This article introduces the main advantages of the multipole system and shows and evaluates some of the most representative experimental results under extreme wind conditions. Copyright

Torres, Eduardo; Garcia-Sanz, Mario

2004-04-01

237

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

NASA Technical Reports Server (NTRS)

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.

Smith-Taylor, Rudeen; Tanner, Sharon E.

1993-01-01

238

REFLECTIONS ON MY CONTRIBUTIONS TO PARTICLE PHYSICS AND RECENT EXPERIMENTAL RESULTS FROM RHIC.  

SciTech Connect

My talk today will be composed of two parts. The first part will consist of a summary of some of my experimental contributions over the years. It will not be exhaustive but will highlight the findings that had relevance to the progress of our understanding of particle physics as it has evolved over the years. This section will be divided into three periods: Early, Intermediate and Late, with an in depth discussion of a few of the more significant results. The second part will consist of a discussion of the recently completed Relativistic Heavy Ion Collider (RHIC) machine at Brookhaven National Laboratory (BNL). This will encompass the parameters of the accelerator and some of the interesting and exciting early experimental results emanating from this machine.

SAMIOS,N.P.

2002-01-18

239

Electromagnetic Inverse-Scattering Reconstructions by an Inexact Newton Method: Numerical and Experimental Results  

NASA Astrophysics Data System (ADS)

This paper deals with the inverse scattering problem for electromagnetic imaging. In particular, a reconstruction procedure based on the inexact Newton method is reviewed. A new formulation, developed in the Lp functional Banach space, is also considered. Numerical and experimental results recently obtained by using the above mentioned reconstruction methods are discussed with specific reference to nondestructive evaluation of dielectric materials such as plastic and wood.

Pastorino, Matteo

2012-09-01

240

Closed Loop Two-Phase Thermosyphon of Small Dimensions: a Review of the Experimental Results  

Microsoft Academic Search

A bibliographical review on the heat and mass transfer in gravity assisted Closed Loop Two Phase Thermosyphons (CLTPT) with\\u000a channels having a hydraulic diameter of the order of some millimetres and input power below 1 kW is proposed. The available\\u000a experimental works in the literature are critically analysed in order to highlight the main results and the correlation between\\u000a mass flow

Alessandro Franco; Sauro Filippeschi

241

Experimental results with a natural gas cogeneration system using a polymer exchange membrane fuel cell  

Microsoft Academic Search

This paper reports experimental results of an investigation of five identical CHP (combined heat and power) units using PEMFC (proton exchange membrane fuel cell) and running on natural gas. The natural gas is reformed locally to produce hydrogen. The net electric power is 4.5kWe and the installations are designed for low temperature heat recovery (6kW at 60°C). The performances of

Mihai Radulescu; Olivier Lottin; Michel Feidt; Christophe Lombard; David Le Noc; Stéphane Le Doze

2006-01-01

242

ISS-b experimental results on global distributions of ionospheric parameters and thunderstorm activity  

Microsoft Academic Search

Experimental results from the Ionosphere Sounding Satellite-b (ISS-b) are presented, with emphasis on the global distribution of such ionospheric parameters as (1) critical frequency (foF2); (2) the probability of occurrence of spread echoes; (3) nighttime electron temperature and ionic constituents of the ambient plasma; and (4) thunderstorms detected by means of radio technique. Detailed maps are presented for all four

N. Matuura; M. Kotaki; S. Miyazaki; E. Sagawa; I. Iwamoto

1981-01-01

243

Natural gas electric generator powered by polymer exchange membrane fuel cell: Numerical model and experimental results  

Microsoft Academic Search

The reduction of pollutant emissions is an important advantage of fuel cells in small stationary power systems, particularly in combined heat and power generation (CHP). In fact, fuel cells are one of the future practical solutions for micro-CHP systems (5–10kW) in the domestic environment. This paper reports numerical and experimental results of 5kWe CHP H-Power units running on natural gas.

M. Radulescu; V. Ayel; O. Lottin; M. Feidt; B. Antoine; C. Moyne; D. Le Noc; S. Le Doze

2008-01-01

244

Predictions of Necking with Analytical Criteria and Comparisons with Experimental Results  

Microsoft Academic Search

Two analytical approaches are detailed for the determination of Forming Limit Diagrams (F.L.D.) and compared with experimental results. The first one is the ``Enhanced Modified Maximum Force Criterion EMMFC'' and the second one is the ``Through-Thickness Shear Instability Criterion TTSIC''. The criteria are both written in an intrinsic analytical form and are applicable to linear and non-linear strain paths as

Michel Brunet; Patrice Clerc

2007-01-01

245

All-digital 1-bit RSFQ Autocorrelator for Radioastronomy Applications: Design and Experimental Results  

Microsoft Academic Search

We present the design of a Rapid SingleFlux-Quantum all-digital one-bit autocorrelator forsubmillimeter spectrometry applications, featuring4 GHz input signal bandwidth, double oversamplingquantizer, and 16 Mbps-per-channel output rate. Thecorrelator consists of a digital delay line with multiplicationand an array of accumulators with parallelread-out. We report experimental results for a 3-stagedelay line (294 Josephson junctions) and a 4 \\\\Theta 4 arrayof accumulators (288

Alexander V. Rylyakov; Stas V. Polonsky

1997-01-01

246

WLAN\\/WDS Performance using Directive Antennas in Highly Mobile Scenarios: Experimental Results  

Microsoft Academic Search

This paper presents experimental results from a series of IEEE 802.11g studies to investigate the performance of vehicular to roadside wireless communications. In particular, two high-gain omni-directional antennas were used at the roadside access point, while high-gain omni-directional and directional antennas were compared for use on the vehicle. By employing high-gain antennas at both ends of the wireless link, the

George Zaggoulos; Andrew Nix

2008-01-01

247

Kinematic Viscosities for Ether + Alkane Mixtures: Experimental Results and UNIFAC-VISCO Parameters  

NASA Astrophysics Data System (ADS)

Kinematic viscosities for the binary mixtures of diisopropylether, dibutylether or methyl ter-butyl ether with 3-methylpentane, hexane or heptane have been measured at 283.15 K, 298.15 K, and 313.15 K. The experimental values have been correlated by the McAllister equation. Using these results, new UNIFAC-VISCO parameters, Oether-CH2 and Oether-CH3, have been calculated.

Bandrés, I.; Lahuerta, C.; Villares, A.; Martín, S.; Lafuente, Carlos

2008-04-01

248

Experimental demonstration of thermoacoustic energy conversion in a resonator.  

PubMed

Using thermoacoustic energy conversions, both amplification and damping of acoustic intensity are demonstrated. A differentially heated regenerator is installed near the velocity node of the resonator and thereby a high specific acoustic impedance and a traveling wave phase are obtained. It is shown that the gain of acoustic intensity resulting from the traveling wave energy conversion reaches 1.7 in a positive temperature gradient and 0.3 in a negative gradient. When the regenerator is replaced with a stack, it is found that the gain reaches 2.3, exceeding the temperature ratio (=1.9) of both ends of the stack. This is brought about by the addition of standing wave energy conversion. The present results would contribute to the development of new acoustic devices using thermoacoustic energy conversion. PMID:15244723

Biwa, Tetsushi; Tashiro, Yusuke; Mizutani, Uichiro; Kozuka, Motoki; Yazaki, Taichi

2004-06-01

249

Experimental studies of pion-nucleus interactions at intermediate energies  

SciTech Connect

This report summarizes the work on experimental research in intermediate energy nuclear physics carried out at New Mexico State University in 1991 under a great from the US Department of Energy. Most of these studies have involved investigations of various pion-nucleus interactions. The work has been carried out both with the LAMPF accelerator at the Los Alamos National Laboratory and with the cyclotron at the Paul Scherrer Institute (PSI) near Zurich, Switzerland. Part of the experimental work involves measurements of new data on double-charge-exchange scattering, using facilities at LAMPF which we helped modify, and on pion absorption, using a new detector system at PSI that covers nearly the full solid-angle region which we helped construct. Other work involved preparation for future experiments using polarized nuclear targets and a new high-resolution spectrometer system for detecting {pi}{sup 0} mesons. We also presented several proposals for works to be done in future years, involving studies related to pi-mesonic atoms, fundamental pion-nucleon interactions, studies of the difference between charged and neutral pion interactions with the nucleon, studies of the isospin structure of pion-nucleus interactions, and pion scattering from polarized {sup 3}He targets. This work is aimed at improving our understanding of the pion-nucleon interaction, of the pion-nucleus interaction mechanism, and of nuclear structure.

Not Available

1991-12-31

250

Experimental and husbandry procedures as potential modifiers of the results of phenotyping tests  

PubMed Central

To maximize the sensitivity of detecting affects of genetic variants in mice, variables have been minimized through the use of inbred mouse lines, by eliminating infectious organisms and controlling environmental variables. However, the impact of standard animal husbandry and experimental procedures on the validity of experimental data is under appreciated. In this study we monitored the impact of these procedures by using parameters that reflect stress and physiological responses to it. Short-term measures included telemetered heart rate and systolic arterial pressure, core body temperature and blood glucose, while longer-term parameters were assessed such as body weight. Male and female C57BL6/NTac mice were subjected to a range of stressors with different perceived severities ranging from repeated blood glucose and core temperature measurement procedures, intra-peritoneal injection and overnight fasting to cage transport and cage changing. Our studies reveal that common husbandry and experimental procedures significantly influence mouse physiology and behaviour. Systolic arterial pressure, heart rate, locomotor activity, core temperature and blood glucose were elevated in response to a range of experimental procedures. Differences between sexes were evident, female mice displayed more sustained cardiovascular responses and locomotor activity than male mice. These results have important implications for the design and implementation of multiple component experiments where the lasting effects of stress from previous tests may modify the outcomes of subsequent ones.

Gerdin, Anna-Karin; Igosheva, Natalia; Roberson, Laura-Anne; Ismail, Ozama; Karp, Natasha; Sanderson, Mark; Cambridge, Emma; Shannon, Carl; Sunter, David; Ramirez-Solis, Ramiro; Bussell, James; White, Jacqueline K.

2012-01-01

251

Percutaneous vascular stent: experimental studies and preliminary clinical results in peripheral arterial diseases.  

PubMed

A new pattern of metallic intravascular stent has been experimentally and clinically tested. When the stent is percutaneously placed through a six french introducer, it is held against the vessel wall by its natural elastic properties. In 28 animals, 47 stents of different sizes (from 3 to 5 mm of luminal diameter and from 1.5 to 5 cm of length) have been implanted in the femoro-popliteal (16), the coronary (20), the carotid (3) and the renal arteries (5) and in 3 femoral veins. Angiographic and histological results have shown the stent's low thrombogenicity when it is well fit to the vessel's caliber. Moreover, they have shown its incorporation to the vessel wall by intimalisation as early as the third week after its implantation. The collateral vessels which covered by the stent remain permeable. At the end of this experimentation, 10 implants have been achieved in 8 patients (4 recurrences of iliac stenosis and 6 femoral stenosis). The angiographic results show the perfect tolerance of the organism at 6 months. This good tolerance is revealed by a thin intraluminal border which does not change the artery's diameter. This confirms the experimental results. The permeability is good except for two patients who had an obliteration after one month (one iliac and one femoral obliteration). PMID:2963080

Rousseau, H; Joffre, J; Puel, J; Imbert, C; Puech, J L; Duboucher, C; Wallsten, H

1987-01-01

252

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

253

Experimental limit on low energy antiprotons in the cosmic radiation  

NASA Technical Reports Server (NTRS)

Results are reported from the Low Energy Antiproton Experiment (LEAP), a balloon-borne instrument which was flown in August, 1987. No evidence of antiproton fluxes is found in the kinetic energy range of 120 MeV to 360 MeV, at the top of the atmosphere. The 90-percent is found confidence upper limit on the antiproton/proton ratio in this energy range is 3.5 x 10 to the -5th. In particular, this new experiment places an upper limit on the flux almost an order of magnitude below the reported flux of Buffington et al. (1981).

Streitmatter, R. E.; Stochaj, S. J.; Ormes, J. F.; Golden, R. L.; Stephens, S. A.

1989-01-01

254

Experimental reconstruction of excitation energies of primary hot isotopes in heavy ion collisions near the Fermi energy  

NASA Astrophysics Data System (ADS)

The excitation energies of the primary hot isotopes in multifragmentation events are experimentally reconstructed in the reaction system 64Zn + 112Sn at 40 MeV/nucleon. A kinematical focusing method is employed to evaluate the multiplicities of the evaporated light particles associated with isotopically identified fragments with 3?Z?14. Angular distributions of the velocity spectra of light charged particles and neutrons associated with trigger isotopes are examined. A moving source fit is used to separate the kinematically correlated particles, evaporated from the parents of the detected isotopes, from the uncorrelated particles originating from other sources. The latter are evaluated experimentally relative to those in coincidence with the Li isotopes. A parameter, k, is used to adjust the yield of the uncorrelated particles for different trigger isotopes. For each experimentally detected isotope, the multiplicities, apparent temperatures, and k values for n, p, d, t, and ? particles are extracted. Using the extracted values, the excitation energies of the primary hot isotopes are reconstructed employing a Monte Carlo method. The extracted excitation energies are in the range of 1 to 4 MeV/nucleon but show a significant decreasing trend as a function of A for a given Z of the isotopes. The results are compared with those of antisymmetrized molecular dynamics (AMD) and statistical multifragmentation model (SMM) simulations. While some of the experimental characteristics are predicted partially by each model, neither simulation reproduces the overall characteristics of the experimental results.

Rodrigues, M. R. D.; Lin, W.; Liu, X.; Huang, M.; Zhang, S.; Chen, Z.; Wang, J.; Wada, R.; Kowalski, S.; Keutgen, T.; Hagel, K.; Barbui, M.; Bottosso, C.; Bonasera, A.; Natowitz, J. B.; Materna, T.; Qin, L.; Sahu, P. K.; Schmidt, K. J.

2013-09-01

255

Experimental investigation of energy balance in plasma arc cutting process  

NASA Astrophysics Data System (ADS)

The present paper describes the power balance of the arc cutting process provided by a plasma torch with steam working medium. The work was concentrated on definition of different power terms including power input as well as effective power utilization and losses as a function of plasma gas flow rate. The work was mostly experimental. The results have shown around 20% of total available power is utilized for material cutting and removing for the studied conditions.

Kavka, T.; Tossen, S.; Maslani, A.; Konrad, M.; Pauser, H.; Stehrer, T.

2014-05-01

256

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

NASA Technical Reports Server (NTRS)

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.

Gladden, Herbert J.; Yeh, Fredrick C.

1993-01-01

257

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

NASA Astrophysics Data System (ADS)

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.

Sinitsyn, Oleksandr; Nusinovich, Gregory; Antonsen, Thomas

2010-11-01

258

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

NASA Astrophysics Data System (ADS)

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.

Gladden, Herbert J.; Yeh, Fredrick C.

1993-04-01

259

Position control of a single-link mechanism activated by shape memory alloy springs: experimental results  

NASA Astrophysics Data System (ADS)

This research involves the application of methods to actively control the vibration of a plate-like structure with discontinuous boundary conditions. The research is motivated by the need to control vibrations on rack shelves in use on the International Space Station (ISS). Vibration of the rack shelves can adversely affect experiments being performed on those shelves. In this work, control of a rack shelf similar to those in use on the ISS is examined. Piezoelectric actuators bonded to the shelf structure are proposed as a method for controlling rack shelf vibrations. A two-dimensional asymmetric piezoelectric actuator model is first developed. The Ritz expansion method is then employed to derive the equations of motion for the combined piezoelectric actuators and rack shelf system with discontinuous boundary conditions. Model parameters from the analytical solution are used in conjunction with experimentally obtained parameters to develop a control model for the active structure. The control model is then used, together with a linear quadratic approach, to develop two different control strategies: collocated output feedback control and modal control. Results from an experimental evaluation of the two control approaches are presented. Based on the experimental results, the two control strategies are shown to be effective in controlling the first several modes of the rack shelf system at frequencies below 800 Hz. Portions of this work were presented in 'Active Control of International Space Station Experiment Rack Shelf Simulator Vibrations', Proceedings of 2004 ASME International Mechanical Engineering Congress, Anaheim, California, November 2004 (IMECE2004-60853).

Wang, Jingdou; Shepard, W. Steve, Jr.; Williams, Keith A.; Gattis, Christy B.

2006-02-01

260

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

NASA Technical Reports Server (NTRS)

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.

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

2001-01-01

261

Comparison of numerical and experimental results of the flow in the U9 Kaplan turbine model  

NASA Astrophysics Data System (ADS)

The present work compares simulations made using the OpenFOAM CFD code with experimental measurements of the flow in the U9 Kaplan turbine model. Comparisons of the velocity profiles in the spiral casing and in the draft tube are presented. The U9 Kaplan turbine prototype located in Porjus and its model, located in Älvkarleby, Sweden, have curved inlet pipes that lead the flow to the spiral casing. Nowadays, this curved pipe and its effect on the flow in the turbine is not taken into account when numerical simulations are performed at design stage. To study the impact of the inlet pipe curvature on the flow in the turbine, and to get a better overview of the flow of the whole system, measurements were made on the 1:3.1 model of the U9 turbine. Previously published measurements were taken at the inlet of the spiral casing and just before the guide vanes, using the laser Doppler anemometry (LDA) technique. In the draft tube, a number of velocity profiles were measured using the LDA techniques. The present work extends the experimental investigation with a horizontal section at the inlet of the draft tube. The experimental results are used to specify the inlet boundary condition for the numerical simulations in the draft tube, and to validate the computational results in both the spiral casing and the draft tube. The numerical simulations were realized using the standard k-e model and a block-structured hexahedral wall function mesh.

Petit, O.; Mulu, B.; Nilsson, H.; Cervantes, M.

2010-08-01

262

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

SciTech Connect

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.

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

2001-08-01

263

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

NASA Astrophysics Data System (ADS)

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.

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

2008-06-01

264

Comparison between maximum radial expansion of ultrasound contrast agents and experimental postexcitation signal results.  

PubMed

Experimental postexcitation signal data of collapsing Definity microbubbles are compared with the Marmottant theoretical model for large amplitude oscillations of ultrasound contrast agents (UCAs). After taking into account the insonifying pulse characteristics and size distribution of the population of UCAs, a good comparison between simulated results and previously measured experimental data is obtained by determining a threshold maximum radial expansion (Rmax) to indicate the onset of postexcitation. This threshold Rmax is found to range from 3.4 to 8.0 times the initial bubble radius, R0, depending on insonification frequency. These values are well above the typical free bubble inertial cavitation threshold commonly chosen at 2R0. The close agreement between the experiment and models suggests that lipid-shelled UCAs behave as unshelled bubbles during most of a large amplitude cavitation cycle, as proposed in the Marmottant equation. PMID:21302993

King, Daniel A; O'Brien, William D

2011-01-01

265

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

NASA Astrophysics Data System (ADS)

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.

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

2014-07-01

266

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

267

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

NASA Astrophysics Data System (ADS)

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.

Olivier, P.; Tiffon, J.

1984-09-01

268

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

NASA Technical Reports Server (NTRS)

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

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

2012-01-01

269

Use of dynamic theory to describe experimental results from volume holography  

NASA Technical Reports Server (NTRS)

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.

Magnusson, R.; Gaylord, T. K.

1976-01-01

270

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

NASA Technical Reports Server (NTRS)

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.

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

2006-01-01

271

Comparison between maximum radial expansion of ultrasound contrast agents and experimental postexcitation signal results  

PubMed Central

Experimental postexcitation signal data of collapsing Definity microbubbles are compared with the Marmottant theoretical model for large amplitude oscillations of ultrasound contrast agents (UCAs). After taking into account the insonifying pulse characteristics and size distribution of the population of UCAs, a good comparison between simulated results and previously measured experimental data is obtained by determining a threshold maximum radial expansion (Rmax) to indicate the onset of postexcitation. This threshold Rmax is found to range from 3.4 to 8.0 times the initial bubble radius, R0, depending on insonification frequency. These values are well above the typical free bubble inertial cavitation threshold commonly chosen at 2R0. The close agreement between the experiment and models suggests that lipid-shelled UCAs behave as unshelled bubbles during most of a large amplitude cavitation cycle, as proposed in the Marmottant equation.

King, Daniel A.; O'Brien, William D.

2011-01-01

272

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

NASA Technical Reports Server (NTRS)

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.

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

2005-01-01

273

Solar Mechanical Energy Storage Program Overview and Systems Analysis Results.  

National Technical Information Service (NTIS)

The current status of the Solar Mechanical Energy Storage Program is described, along with the remaining activities before Lawrence Livermore Laboratory assumes program responsibility in October 1979. Contractor results are presented in other papers; prel...

B. C. Caskey

1979-01-01

274

LONG-TERM RESULTS OF LOWER ENERGY TRANSURETHRAL MICROWAVE THERMOTHERAPY  

Microsoft Academic Search

PurposeWe evaluate long-term results of lower energy transurethral microwave thermotherapy (Prostasoft 2.0*) and identify pretreatment characteristics that predict a favorable outcome.*Technomed Medical Systems, Lyon, France.

G. B. J. M. KEIJZERS; E. A. E. FRANCISCA; F. C. H. D'ANCONA; L. A. L. M. KIEMENEY; F. M. J. DEBRUYNE; J. J. M. C. H. de la ROSETTE

1998-01-01

275

Experimental results from a DC photocathode electron gun for an IR FEL  

SciTech Connect

A 350 keV DC photocathode gun capable of delivering the high-brightness CW electron beam necessary for Jefferson Lab`s infrared free-electron laser is described. The gun is to be used with a superconducting radiofrequency linac operating at 1.497 GHz and is mode-locked to the 40th subharmonic of the fundamental using a Nd:YLF drive laser. The gun provides 20--25 ps bunches at up to 135 pC/bunch. Experimental measurements of transverse and longitudinal beam properties are presented. Transverse emittance is measured using a slit-wire scanner emittance meter, and energy spread is measured using the slit and a spectrometer magnet. Longitudinal emittance is measured using a combination of sampling aperture, kicker cavity, slit and spectrometer. Measurements for bunch charges of 135 pC are described and compared with simulations.

Kehne, D.; Engwall, D.; Legg, R.; Shinn, M.

1997-10-01

276

Real-time measurements of D/log-E curves in holographic emulsions: experimental results  

NASA Astrophysics Data System (ADS)

The response curve D-Log E is the most important method to characterize photographic emulsions. In this work we present the experimental study using a real time technique that can be applied to the improvement of the holographic properties of emulsions. We have exposured an Agfa Gevaert 8E56HD emulsion with an Argon laser tuned at 514 nm. After it, we measured the transmittance curve when the emulsion was into the developer bath function of time at 20 degrees Celsius. This method gives us the possibility of study the dynamics of different developers as a function of the storage energy. It also provides a way to optimize the composition of developers function of the chemical composition, temperature and other secondary factors as superaditivity and non-linear processes.

Fimia, Antonio; Blaya-Escarre, Salvador; Carretero-Lopez, Luis; Madrigal, Roque F.; Mallavia, Ricardo M.

1999-03-01

277

Corrosion by liquid lead and lead-bismuth: experimental results review and analysis  

SciTech Connect

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.

Zhang, Jinsuo [Los Alamos National Laboratory

2008-01-01

278

Nonconstant diffusion coefficients: short description of modeling and comparison to experimental results  

NASA Astrophysics Data System (ADS)

Chemical changes within a resist material (for example, resulting from the exposure and subsequent chemical reactions during post exposure bake) will in general, result in a change in diffusivity of components within that material. In the case of positive chemically amplified resists, the diffusivity of the photo-generated acid changes as a function of the extent of polymer deprotection. The deprotection reaction leads to the generation of small reaction product molecules, some of which are volatile. The liberation of these reaction products causes an increase in the free volume and changes in the chemical behavior in the exposed area. These changes, primarily the increase in free volume, results in an increase in the diffusivity of the acid. Low exposure areas have lower acid diffusivity, leading to a lower efficiency of reaction. This results in a contrast enhancement of the latent image due to the concentration dependent diffusivity of the acid. In this paper, a concentration dependent diffusivity expression is incorporated into a lithography simulator to explore these effects on lithographic performance. Using the assumption of free volume, suitable expressions for the diffusivity are examined and compared to experimentally measured values. The experimental work consists of XP-9402 positive acting, chemically amplified resist that was imaged using different thermal doses.

Petersen, John S.; Mack, Chris A.; Sturtevant, John L.; Byers, Jeffrey D.; Miller, Daniel A.

1995-06-01

279

Experimental study on a simulated primary-pipe rupture accident of HTGR. Experimental results of air ingress behavior.  

National Technical Information Service (NTIS)

In order to investigate the air ingress process following a primary coolant pipe of the HTGR ruptures, we constructed an experimental apparatus simulating the reactor and the primary cooling system. A test model consists of a reactor core simulator, a top...

T. Takeda S. Takenaka M. Hishida K. Emori T. Agake

1993-01-01

280

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

NASA Technical Reports Server (NTRS)

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.

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

2011-01-01

281

Blind deconvolution applied to acoustical systems identification with supporting experimental results.  

PubMed

Many acoustical applications require the analysis of a signal that is corrupted by an unknown filtering function. Examples arise in the areas of noise or vibration control, room acoustics, structural vibration analysis, and speech processing. Here, the observed signal can be modeled as the convolution of the desired signal with an unknown system impulse response. Blind deconvolution refers to the process of learning the inverse of this unknown impulse response and applying it to the observed signal to remove the filtering effects. Unlike classical deconvolution, which requires prior knowledge of the impulse response, blind deconvolution requires only reasonable prior estimates of the input signal's statistics. The significant contribution of this work lies in experimental verification of a blind deconvolution algorithm in the context of acoustical system identification. Previous experimental work concerning blind deconvolution in acoustics has been minimal, as previous literature concerning blind deconvolution uses computer simulated data. This paper examines experiments involving three classical acoustic systems: driven pipe, driven pipe with open side branch, and driven pipe with Helmholtz resonator side branch. Experimental results confirm that the deconvolution algorithm learns these systems' inverse impulse responses, and that application of these learned inverses removes the effects of the filters. PMID:14587599

Roan, Michael J; Gramann, Mark R; Erling, Josh G; Sibul, Leon H

2003-10-01

282

Blind deconvolution applied to acoustical systems identification with supporting experimental results  

NASA Astrophysics Data System (ADS)

Many acoustical applications require the analysis of a signal that is corrupted by an unknown filtering function. Examples arise in the areas of noise or vibration control, room acoustics, structural vibration analysis, and speech processing. Here, the observed signal can be modeled as the convolution of the desired signal with an unknown system impulse response. Blind deconvolution refers to the process of learning the inverse of this unknown impulse response and applying it to the observed signal to remove the filtering effects. Unlike classical deconvolution, which requires prior knowledge of the impulse response, blind deconvolution requires only reasonable prior estimates of the input signal's statistics. The significant contribution of this work lies in experimental verification of a blind deconvolution algorithm in the context of acoustical system identification. Previous experimental work concerning blind deconvolution in acoustics has been minimal, as previous literature concerning blind deconvolution uses computer simulated data. This paper examines experiments involving three classical acoustic systems: driven pipe, driven pipe with open side branch, and driven pipe with Helmholtz resonator side branch. Experimental results confirm that the deconvolution algorithm learns these systems' inverse impulse responses, and that application of these learned inverses removes the effects of the filters.

Roan, Michael J.; Gramann, Mark R.; Erling, Josh G.; Sibul, Leon H.

2003-10-01

283

LNG fires: a review of experimental results, models and hazard prediction challenges.  

PubMed

A number of experimental investigations of LNG fires (of sizes 35 m diameter and smaller) were undertaken, world wide, during the 1970s and 1980s to study their physical and radiative characteristics. This paper reviews the published data from several of these tests including from the largest test to date, the 35 m, Montoir tests. Also reviewed in this paper is the state of the art in modeling LNG pool and vapor fires, including thermal radiation hazard modeling. The review is limited to considering the integral and semi-empirical models (solid flame and point source); CFD models are not reviewed. Several aspects of modeling LNG fires are reviewed including, the physical characteristics, such as the (visible) fire size and shape, tilt and drag in windy conditions, smoke production, radiant thermal output, etc., and the consideration of experimental data in the models. Comparisons of model results with experimental data are indicated and current deficiencies in modeling are discussed. The requirements in the US and European regulations related to LNG fire hazard assessment are reviewed, in brief, in the light of model inaccuracies, criteria for hazards to people and structures, and the effects of mitigating circumstances. The paper identifies: (i) critical parameters for which there exist no data, (ii) uncertainties and unknowns in modeling and (iii) deficiencies and gaps in current regulatory recipes for predicting hazards. PMID:17156916

Raj, Phani K

2007-02-20

284

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

PubMed

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. PMID:23831004

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

2013-11-01

285

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

PubMed

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

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

2013-12-28

286

Future directions in high energy electron-positron experimentation  

SciTech Connect

In this report, the possibilities of studying particle physics at the TeV scale with high energy electron-positron linear colliders are discussed. A status report on the SLC and the MARK II program is given to provide some insights on the feasibility of experiments at linear colliders. The technical issues in going from SLC to the development of TeV colliders are briefly discussed. Some of the elements of the e/sup +/e/sup -/ experimental environment which differentiate it from that in hadron colliders and give examples of processes particularly well suited to attack by e/sup +/e/sup -/ annihilation are summarized. Finally, some concluding remarks are given. 8 refs., 10 figs., 2 tabs.

Trilling, G.H.

1988-09-01

287

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

NASA Astrophysics Data System (ADS)

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 ? = 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.

Kaya, Ahmet; Ayd?n, Orhan; Dincer, Ibrahim

2010-05-01

288

Failure properties of two porous sandstones: experimental results and the applicability of a theoretical prediction  

NASA Astrophysics Data System (ADS)

True triaxial experiments have been performed in Coconino (n = 17%) and Bentheim (n = 24%) sandstones using two distinct loading paths. Tests using a novel loading path maintain a constant deviatoric stress state N (= -?2(?2 - ?oct)/?oct, Rudnicki and Rice, 1975), by keeping ?3 constant and raising ?1 and ?2 simultaneously at a predetermined ratio of (?2 - ?3)/(?1 - ?3) until failure occurs. Experiments were conducted for an array of seven ?3 magnitudes between 0 and 150 MPa, and five stress ratios (between 0 and 1), i.e., five N magnitudes between +1 (axisymmetric compression) and -1 (axisymmetric extension). Test data for Coconino show that for each constant N the octahedral shear stress at failure, ?oct,f, rises as the mean stress, ?oct,f increases, albeit at a decreasing rate; in Bentheim sandstone, ?oct,f not only rises at a decreasing rate with increasing ?oct,f, but reaches a peak and forms a ';cap', beyond which it continuously drops with a rise in ?oct,f. In both rocks, for a constant ?oct,f, ?oct,f typically increases as N varies from +1 (?2 = ?3) to -1 (?2 = ?1). Tests using the common loading path, maintain constant both ?2 and ?3, while raising ?1 monotonically to failure (?1,peak). In these tests, ?1,peak first rises with an increase in the constant ?2 beyond ?2 = ?3. The rate of increase slows down for higher ?2, until a top magnitude is reached, beyond which ?1,peak drops continuously as ?2 is raised from test to test, and approaches its initial magnitude when ?2 = ?1. Under the assumption that ?2 effect on failure in the common loading path tests is caused by changes in both ?oct and N, we fitted the novel test data with the three-invariant failure representation F (?oct, ?oct, N) = 0 (proposed by Rudnicki, 2008), and used this expression to predict ?1,peak = f (?2, ?3) for each constant ?3 series. We then compared the experimental results with the theoretical predictions. The failure prediction in both sandstones generally replicates the strengthening effect of ?2 observed experimentally. In Coconino, predicted ?1,peak underestimates somewhat experimental magnitudes at the two extremes of ?2 (?2 = ?3 and ?2 = ?1). In Bentheim, the trend for the theoretical failure point is to slightly over-predict experimental results. Generally, the predicted ?1,peak in both sandstones yields a reasonable fit to experimental data.

Ma, X.; Rudnicki, J. W.; Haimson, B. C.

2013-12-01

289

Silicon Carbide Epitaxy in a Vertical CVD Reactor: Experimental Results and Numerical Process Simulation  

NASA Astrophysics Data System (ADS)

In this paper an overview is given on the epitaxial growth of SiC in a vertical CVD reactor. Results concerning impurity incorporation and ways to achieve background doping levels as low as 1014 cm - 3 are discussed. Precise control of the C/Si ratio in the gas phase, which is easily achieved in the described reactor, and the use of reduced pressure, lead to good control of dopant incorporation over more than three orders of magnitude, and smooth surface morphology at growth rates higher than 5 m/h. Doping variations <+/-12% across 35 mm wafers can routinely be obtained. The quality of the epilayers is proven by electrical brakdown fields as high as 2×106 V/cm at NA - ND = 5×10 - 15 cm - 3 achieved in both pn and Schottky diodes and an electron mobility higher than 700 cm2/Vs at 300 K (4H-SiC) estimated from the on-resistance of these test devices. Another important experimental boundary condition, the influence of the gas composition at the end of the epitaxial growth process on the surface properties of the epitaxial layer, is described. It will be shown that surfaces nearly resistant against oxidation can be generated in a hydrogen free atmosphere. As a second main topic of this paper, results of an elaborate numerical process simulation will be described including both fluid mechanical and chemical behavior. The influence of the main process parameters like total flow, chamber pressure, and rotation speed on the stability of the flow was investigated. The results achieved are compared with experimental observations showing excellent agreement. The experimental observation of an irradiant layer in the gas phase in front of the wafer under typical process conditions is explained with the help of the numerical model. The usefulness of this specific feature for the optimization of process conditions is discussed.

Rupp, R.; Makarov, Yu. N.; Behner, H.; Wiedenhofer, A.

1997-07-01

290

Shock waves in rapid flows of dense granular materials: theoretical predictions and experimental results.  

PubMed

Strong shocks in rapid dense granular flows are studied theoretically and analyzed in detail to compare with benchmark experimental data. The experimental data includes particle image velocimetry measurements of dry granular flow following its continuous release from a silo. The rapidly moving material down the chute impinges on an obstruction wall erected perpendicular at the end of a long and steep channel. Impact leads to a sudden change in the flow regime from a fast moving supercritical thin layer to a stagnant thick heap with variable thickness. This flow configuration is particularly interesting because it is analogous to some hydraulic and aerodynamic situations. We present results about the depth and the velocity evolution and their comparisons with theoretical predictions associated with frictional granular flow equations incorporating anisotropic pressure conditions. These flow equations are integrated by implementing high-resolution nonoscillatory central differencing total variation diminishing schemes. The dynamical and geometrical effects of the flow will be discussed in detail. These include geometry evolution and depositions at supercritical and subcritical flows, the impact velocity, shock speed, its position and evolution, choice of numerical limiters, and the influence of friction angles on the dynamics and depositions. An excellent agreement between theoretical predictions and experimental observations will be demonstrated. These results can be applied to estimate impact pressures exerted by avalanches on defense structures or infrastructure along the channel and in the run-out zones, and to study the complex flow dynamics around the obstacles and in depositions when the mass comes suddenly to a standstill. Importantly, these results can form a basis for calibration of numerical simulations when strong shocks occur in granular flows. PMID:18999419

Pudasaini, Shiva P; Kröner, Christian

2008-10-01

291

Experimental and Analytical Studies on Pyroelectric Waste Heat Energy Conversion  

NASA Astrophysics Data System (ADS)

This study is concerned with direct conversion of thermal energy into electrical energy by subjecting pyroelectric materials to the Olsen cycle. The Olsen cycle consists of two isoelectric field and two isothermal process on the electric displacement versus electric field diagram. The energy and power generation capabilities of copolymer poly(vinylidene fluoridetrifluorethylene) [P(VDF-TrFE)] films and lead lanthanum zirconate titanate (PLZT) ceramics were evaluated by executing the Olsen cycle via so-called "stamping experiments" and "dipping experiments". The stamping experiments consisted of alternatively pressing a pyroelectric material in thermal contact with hot and cold aluminum blocks under specified electric fields. It was performed to assess the pyroelectric energy conversion performance using heat conduction. The largest energy density generated in the stamping experiments was 155 J/L/cycle with 60/40 P(VDF-TrFE) thin film at 0.066 Hz between 25 and 110°C and electric fields cycled between 20 and 35 MV/m. This energy density exceeded the 130 J/L/cycle achieved by our previous prototypical device using oscillatory laminar convective heat transfer. However, the performance was limited by poor thermal contact between the aluminum blocks and pyroelectric material and also by excessive leakage current inherent to P(VDF-TrFE) at high temperatures and/or large electric fields. On the other hand, dipping experiments consisted of successively immersing a pyroelectric material into isothermal hot and cold thermal reservoirs at different temperatures while simultaneously cycling the electric fields. It was performed on relaxor ferroelectric x/65/35 PLZT ceramics with x between 5 and 10 mol.%. The operating temperature, applied electric field, sample thickness, cycle frequency, and electrode material were systematically varied to explore their respective effects on the energy and power densities produced. A maximum energy density of 1014 J/L/cycle was obtained with a 190?m thick 7/65/35 PLZT sample at 0.0256 Hz at temperatures between 30 and 200°C and electric field from 0.2 to 7.0 MV/m. To the best of our knowledge, this energy density is the largest achieved among pyroelectric single crystals, ceramics, and polymers using the Olsen cycle. Meanwhile, a maximum power density of 55.3 ± 8.0 W/L obtained with a 190?m thick 9.5/65/35 PLZT sample at 0.125 Hz. Additionally, the temperature-dependent dielectric behavior of PLZT ceramics were characterized. The polarization transition temperature of lanthanum-doped x /65/35 PLZT ceramics decreased from 240 to 10°C for increasing lanthanum dopant concentration x from 5 to 10 mol.%. This establishes that the different compositions should be operated at different temperatures for maximum pyroelectric energy conversion. Finally, a physical thermo-electrical model for estimating the energy harvested by ferroelectric relaxors was further validated against experimental data for a wide range of electric fields and temperatures.

Lee, Felix

292

Experimental results of a new system using microwaves for vision correction  

NASA Astrophysics Data System (ADS)

Technology is in development to correct vision without the use of lasers or cutting of the eye. Many current technologies used to reshape the cornea are invasive, in that either RF needles are placed into the cornea or a flap is cut and then a laser used to ablate the cornea in the optical zone. Keraflex, a therapeutic microwave treatment, is a noninvasive, non-incisional refractive surgery procedure capable of treating myopia (nearsightedness). The goal is to create a predictable refractive change in the optical zone, while preserving the epithelium and deeper structures of the eye. A further goal is to avoid incisions and damage to the epithelium which both require a post-treatment healing period. Experimental work with fresh porcine eyes examined the following variables: duration of the RF pulse, RF power level, coolant amount and timing, electrode spacing, applanation force against the eye, initial eye temperature, and age of eye. We measured curvature changes of the eye with topography, Scheimpflug, Wavefront aberrometry or other means to characterize diopter change as an important endpoint. Other assessment includes evaluation of a fine white ring seen in the cornea following treatment. Dose studies have been done to correlate the treated region with energy delivered. The timing and dosing of energy and cooling were investigated to achieve the target diopter change in vision.

Ryan, Thomas P.; Pertaub, Radha; Meyers, Steven R.; Dresher, Russell P.; Scharf, Ronald

2009-02-01

293

Universe Clinopyroxene barometer -recalibrations on the results of the orthopyroxene thermobarometry and experimental results and applications to the clinopyroxene geotherms  

NASA Astrophysics Data System (ADS)

The internal exchange of Jd-Di components on clinopyroxene allow to calibrate the universal clinopyroxene thermobarometer (Ashchepkov, 2001; 2002; 2003) based on experimental data for different systems including peridotitic, eclogitic and igneous which are represented by the augite cumulates as well as salites from the basic granulates from low crust. The equation to the peridotitic system was calibrated on the results of the othopyroxene thermobarometry (Brey. Kohler,1990- McGregor,1974). Modifications allow receiving the better agreement with the orthopyroxene estimates and results of polymineral thermobarometry (Brey, Kohler, 1990) as well as the clinopyroxene thermobarometry (Nimis, Taylor, 2000). The following equation allows working with the peridotite of the mantle lithosphere beneath cratons (30-80) kbar. P(Ash2009)=0.32 (1-0.2*Na/Al+0.012*Fe/Na)*Kd^(3/4)*ToK/(1+Fe)-35*ln(1273/ToK)*(Al+Ti+2.5Na+1.5Fe3+)+(0.9-CaO)*10+Na20/Al2O3*ToK /200 with the second iteration P=(0.0000002* P4 +0.000002+P^3-0.0027*P^2+1.2241*P) Checking of the HP experiments (Brey et al 2008, Walter, 1998; Falloon, Green, 1989; Dasgupta et al., 2007 etc.) it show the precision close to those of the best barometers (McGregor, 1974) ~5-7 but much more wider compositional range including metasomatic associations and The equation for the Al - rich assemblages allow to obtain the pressure estimates fro the megacrystalls and Al - rich peridotitic clinopyroxenes from the mantle xenoliths carried by alkaline basalts: P(Ash2009)=0.035*Kd*ToK(1+2.44Fe)-50.2 ln(1273/ToK) (Al+Ti+Na) Together with the clinopyroxene thermometer (Nimis, Taylor, 2000) it produces the TP estimates very close to those obtained with (Brey, Kohler, 1990) and values of experiments for the melting of basalts. The meagacrystalls show the polybaric origin and their range of estimated pressure corresponds well to determined for mantle peridotites and pyroxenites. The clinopyroxene geotherms for S. Africa (Boyd, Nixon, 1974), Siberia (Boyd et al., 1997) and North America (Kopylova et al., 1998) are reproducing the TP estimates b set the values for all mantle associations simultaneously. Such geotherms show the complex nature and wide ranges for TP gradients and variations of temperatures at the same level for the large pipes. This I results of the joining subduction, conductive and advective TP of several melts portions passed through the mantle columns. The vast heating and metasomatic modifications were manly produced by the The eclogite geotherms for the kimberlites reveal two branches - LT close to subduction and HT close to the TP path pf protokimberlites determined by megacrystalline assemblages. The TP values for the typical subduction eclogites (Dora Maira, East China, Tibet) reveal the range of pressures from 11 to 45 kbars and varying gradients mostly close to LT subduction type. The exact values are highly dependent on the thermometer used. The Krough, 1988 and slightly modified (Nimis, Taylor , 2000) give comparable results. Grant RBRF 05-05-64718.

Ashchepkov, I. V.

2009-04-01

294

Electrochemical impedance spectroscopy study of nickel-iron deposition. 1: Experimental results  

SciTech Connect

Results of an electrochemical impedance spectroscopy study of nickel-iron codeposition are presented. Impedance spectra are influenced in a complicated manner by the applied current density, rotation speed, and concentration of ferrous ions. Spectra are particularly sensitive to current density and ferrous-ion concentration. As a basis for comparison, an experimental and theoretical study of nickel deposition from an iron-free bath is presented. It is found that it is the inductive loop of the impedance spectra that changes most dramatically in the presence of ferrous ions.

Baker, B.C.; West, A.C. [Columbia Univ., New York, NY (United States). Dept. of Chemical Engineering, Materials Science, and Mining Engineering

1997-01-01

295

Experimental code verification results for reflector antenna distortion compensation by array feeds  

NASA Technical Reports Server (NTRS)

Electronic compensation of reflector surface distortion using array feed with individual amplitude and phase control of the array elements is becoming increasingly attractive because of the recent advances in monolithic microwave integrated circuit (MMIC) technology. An algorithm has been developed previously using the concept of focal plane conjugate field matching in the receive mode and a computer code has been generated that predicts the proper excitation coefficients for the elements of the reflector feed array to compensate the effects of reflector surface distortion. This paper presents the results of an experimental study to verify the above compensation algorithm and in general to demonstrate the effectiveness of the array feed compensation technique.

Zaman, A. J.; Rahmat-Samii, Y.; Woo, K.

1992-01-01

296

Nucleate pool boiling in subcooled liquid under microgravity: Results of TEXUS experimental investigations  

NASA Astrophysics Data System (ADS)

Experiments on subcooled nucleate pool boiling in microgravity were carried out to separate gravity driven effects on heat transfer within the boiling process. A ballistic trajectory by sounding rocket flight (TEXUS 5 and 10) achieved a gravity level of a/g = 0.0001 for 360 sec. For determination of geometrical effects on heat transport two different experimental configurations (platinum wire and flat plate) were employed. Boiling curves and bubble dynamics recorded by cinematography lead to gravity independent modelling of the boiling phenomena. The results ensure the applicability and high efficiency of nucleate pool boiling for heat exchangers in space laboratories.

Zell, M.; Straub, J.; Weinzierl, A.

1984-12-01

297

Voltammetry and coulometry with immersed thin layer electrodes. Part 2: Practical considerations and experimental results  

NASA Astrophysics Data System (ADS)

We have shown that geometrical considerations in the design of immersed thin layer electrochemical cells are important in the satisfactory performance of voltammetric experiments in solutions of high specific resistivity. In this paper, practical cell design and experimental results for a variety of systems are considered. In summary, we feel that reasonable care in the design of thin layer cells leads to the quantitative use of voltammetry and coulometry in systems with high specific resistivities. In the end, the effort is not much more than that required for conventional cyclic voltammetry, whereas the advantages of analysis using thin layer techniques are greater than those in conventional voltammetry.

Hinman, A. S.; Pons, S.; Cassidy, J.

1984-11-01

298

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

NASA Technical Reports Server (NTRS)

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.

Dewey, J. S.; Devasia, Santosh

1996-01-01

299

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

300

Sound scattering by the seafloor: Results of recent theoretical and experimental research  

NASA Astrophysics Data System (ADS)

The state of theoretical and experimental research in sound scattering by the seafloor is considered. Current geoacoustic models are discussed. In general, these models make it possible to consider bottom sediments as an arbitrary stratified medium having statistically irregular interfaces and random volume heterogeneities, both continuous and/or discrete. The outlook for further development and practical use of the model are analyzed with emphasis on advancing techniques for acoustic sensing of marine sediments. Results of comparisons with data of the latest large-scale experiments on sound scattering by a shallow-water seafloor are given.

Ivakin, A. N.

2012-03-01

301

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

NASA Technical Reports Server (NTRS)

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.

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

1983-01-01

302

Transient thermography as a through skin imaging technique for aircraft assembly: modelling and experimental results  

NASA Astrophysics Data System (ADS)

Transient-pulsed thermography was used as a through skin imaging technique with the intention of locating anchoring points beneath the outer skins of aircraft structures. A representative test structure, comprising a thin skin positioned over a thick strut fixture, was investigated experimentally and analysed using finite difference thermal modelling software. Both carbon fibre reinforced plastic (CFRP) and aluminium structures were investigated. The ability of the technique to detect a subsurface fixing and to provide information about its location was analysed. Results indicate a precision of better than 0.5 mm to be achievable.

Avdelidis, N. P.; Almond, D. P.

2004-03-01

303

Experimental results in nonlinear compensation of a one degree-of-freedom magnetic suspension  

NASA Technical Reports Server (NTRS)

Nonlinear control techniques are of increasing interest in magnetic bearing applications. A one-degree-of-freedom magnetic suspension system has been constructed to serve as a test system for nonlinear control. The objective of this effort is to build an accurate model for the nonlinear suspension dynamics and to show the advantages of compensating for these nonlinearities by using a nonlinear controller. The results obtained with a nonlinear controller are experimentally demonstrated as superior to those obtained with a linear controller. Specifically, a controller which contains a force-control block yields transient responses which are largely independent of the operating point air gap.

Trumper, David L.; Sanders, James C.; Nguyen, Tiep H.; Queen, Michael A.

1992-01-01

304

Experimental results of radio observations at the Yakutsk EAS in 2009-2011  

NASA Astrophysics Data System (ADS)

Results of radio emission measurements at 30-34 MHz from extensive air shower particles with primary energy above 1017 eV are presented. The data recorded at the Yakutsk EAS for the period 2009 - 2011 years with energies above 1017 eV, zenith angles less than 60 degree, the axes of which were within a large EAS. The shape of the spatial distribution has a different slope, depending on the distance to the shower axis. At large distances R > 500 m from the shower radio emission is small and almost constant up to a distance of 800 m. The primary energy of EAS and the amplitude of the peak radio pulse are correlated.

Knurenko, S. P.; Kozlov, V. I.; Petrov, Z. E.; Pravdin, M. I.

2013-02-01

305

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

PubMed

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??Pa 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

Fricke, Moritz B; Rolfes, Raimund

2013-11-01

306

A perspective on thermal annealing of reactor pressure vessel materials from the viewpoint of experimental results  

SciTech Connect

It is believed that in the next decade or so, several nuclear reactor pressure vessels (RPVs) may exceed the reference temperature limits set by the pressurized thermal shock screening criteria. One of the options to mitigate the effects of irradiation on RPVs is to thermally anneal them to restore the toughness properties that have been degraded by neutron irradiation. This paper summarizes recent experimental results from work performed at the Oak Ridge National Laboratory to study the annealing response, or ``recovery`` of several irradiated RPV steels. The fracture toughness is one of the important properties used in the evaluation of the integrity of RPVs. Optimally, the fracture toughness is measured directly by fracture toughness specimens, such as compact tension or precracked Charpy specimens, but is often inferred from the results of Charpy V-notch impact specimens. The experimental results are compared to the predictions of models for embrittlement recovery which have been developed by Eason et al. Some of the issues in annealing that still need to be resolved are discussed.

Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

1996-04-01

307

Design oriented simulation for plasma arc cutting consumables and experimental validation of results  

NASA Astrophysics Data System (ADS)

Electrode and nozzle erosion mechanisms in plasma arc cutting processes of mild steel have been studied while designing a prototype mono-gas plasma torch, operating in the range 25-160 A. The correlation between the distribution of different quantities inside the plasma chamber and the erosion mechanisms of the hafnium emitter surface and of the nozzle inner surfaces have been investigated by means of a 2D ANSYS FLUENT-based numerical model, with the final aim of optimizing the overall performances of the prototype. Modelling and numerical simulation have allowed better understanding of the physical phenomena evidenced by experimental results and have suggested successful design solutions for consumables (in particular nozzle, electrode and primary gas diffusers). The correlation between the results of experimental tests and numerical simulations has proven useful in overcoming the critical aspects initially pointed out, significantly improving the expected lifetime of consumables. Results have been analyzed with respect to plasma behaviour, and conclusions have been drawn, concerning the powerfulness of numerical simulation as a tool for designing plasma cutting torches.

Colombo, V.; Concetti, A.; Ghedini, E.; Dallavalle, S.

2011-06-01

308

Experimental limit on the cosmic diffuse ultrahigh energy neutrino flux.  

PubMed

We report results from 120 h of live time with the Goldstone lunar ultrahigh energy neutrino experiment (GLUE). The experiment searches for < or = 10 ns microwave pulses from the lunar regolith, appearing in coincidence at two large radio telescopes separated by 22 km and linked by optical fiber. Such pulses would arise from subsurface electromagnetic cascades induced by interactions of > or = 100 EeV (1 EeV = 10(18) eV neutrinos in the lunar regolith. No candidates are yet seen, and the implied limits constrain several current models for ultrahigh energy neutrino fluxes. PMID:15323748

Gorham, P W; Hebert, C L; Liewer, K M; Naudet, C J; Saltzberg, D; Williams, D

2004-07-23

309

Soil clean up by venting: comparison between modelling and experimental VOC removal results.  

PubMed

Many investigations into specific or accidental pollution relate to hydrocarbons of oil origin: fuels (gasoline or gas oil), fuel oil and lubricants. Pollution by petroleum products is a source of volatile organic compounds in soil. Therefore, laboratory column venting experiments were completed in order to investigate the removal of a pure compound (toluene) and a mixture of two (toluene and n-heptane) and five (toluene, n-heptane, ethylbenzene, m-xylene and p-xylene) compounds. The choice of the compounds, as well as their proportion in the mixture was made on the basis of the real fuel composition. The objective of this study is a comparison between the experimental volatile organic compounds removal results and the predicted values of a simple classical analytical mathematical model that enables the modelling of the venting process. The proposed model for the contaminants transport describes the removal of organic compounds from soil, the contaminants being distributed among four phases: vapour, nonaqueous liquid phase, aqueous and "solid" phase; local phases equilibrium and ideal behaviour of all four phases were found to be accurate enough to describe the interphase mass transfer. The testing of the mathematical model accuracy has been done by using the following performance criteria: dynamic absolute error, average error, model accuracy and correlation coefficient. The reasonable agreement between the predicted and the experimental results as well as the values of the performance criteria prove that the mathematical model is suitable to describe the removal of volatile organic compounds pollutants by venting in the range of experimental conditions used in the pilot plant. PMID:17970522

Brusturean, G A; Todinca, T; Perju, D; Carré, J; Bourgois, J

2007-10-01

310

Spacecraft Power Beaming Using High-Energy Lasers, Experimental Validation  

SciTech Connect

The lifetime of many spacecrafts are often limited by degradation of their electrical power subsystem, e.g. radiation-damaged solar arrays or failed batteries. Being able to beam power from terrestrial sites using high energy lasers, could alleviate this limitation, extending the lifetime of billions of dollars of satellite assets, as well as providing additional energy for electric propulsion that can be used for stationkeeping and orbital changes. In addition, extensive research at the Naval Postgraduate School (NPS) has shown the potential for annealing damaged solar cells using lasers. This paper describes that research and a proposed experiment to demonstrate the relevant concepts of high energy laser power beaming to an NPS-built and operated satellite. Preliminary results of ground experiment of laser illuminations of some of the solar panels of one of the spacecrafts are also presented.

Michael, Sherif [Naval Postgraduate School ECE Dep./Space Systems Academic Group, Monterey, CA 93943 (United States)

2008-04-28

311

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

PubMed Central

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.

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

2011-01-01

312

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

NASA Technical Reports Server (NTRS)

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.

Rollbuhler, Jim

1991-01-01

313

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

NASA Astrophysics Data System (ADS)

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.

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

2014-06-01

314

Gas-dynamic trap: an overview of the concept and experimental results  

NASA Astrophysics Data System (ADS)

A gas dynamic trap (GDT) is a version of a magnetic mirror whose characteristic features are a long mirror-to-mirror distance, which exceeds the effective mean free path of ion scattering into a loss cone, a large mirror ratio (R ˜ 100) and axial symmetry. Under these conditions, the plasma confined in a GDT is isotropic and Maxwellian. The rate at which it is lost out of the ends is governed by a set of simple gas-dynamic equations, hence the name of the device. Plasma magnetohydrodynamic stability is achieved through a plasma outflow through the end mirrors into regions, where the magnetic-field lines' curvature is favorable for this stability. A high flux volumetric neutron source based on a GDT is proposed, which benefits from the high ? achievable in magnetic mirrors. Axial symmetry also makes the GDT neutron source more maintainable and reliable, and technically simpler. This review discusses the results of a conceptual design of the GDT-based neutron source for fusion materials development and fission-fusion hybrids. The main physics issues related to plasma confinement and heating in a GDT are addressed by the experiments performed with the GDT device in Novosibirsk. The review concludes by updating the experimental results obtained, a discussion about the limiting factors in the current experiments and a brief description of the design of a future experimental device for more comprehensive modeling of the GDT-based neutron source.

Ivanov, A. A.; Prikhodko, V. V.

2013-06-01

315

Experimental measurement of gas diffusivity in bitumen: Results for carbon dioxide  

SciTech Connect

A new technique is developed to measure the diffusivity of gas in bitumen as a function of composition. Results are presented for a carbon dioxide-bitumen system, which is of considerable industrial relevance. The technique employs transient pressure data obtained from a nonintrusive pressure decay experiment at constant temperature and volume. The underlying theory is presented along with a computational algorithm to calculate diffusivity. Using experimental pressure decay data in the range 25--90 C at 4 MPa, the diffusivity of carbon dioxide in bitumen is calculated. The results are compared with the limited data available in the literature. The approach is straightforward and can be easily applied to other nonvolatile liquid systems.

Upreti, S.R.; Mehrotra, A.K.

2000-04-01

316

Experimental Results for a Flapped Natural-Laminar-Flow Airfoil with High Lift/Drag Ratio  

NASA Technical Reports Server (NTRS)

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.

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

1984-01-01

317

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

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

318

Computational Fluid Dynamics Prediction of Grid Spacer Thermal-Hydraulic Performance with Comparison to Experimental Results  

SciTech Connect

The thermal-hydraulic performance of a nuclear reactor fuel assembly grid spacer is predicted using computational fluid dynamics. The modeled flow domain exploits the periodicity of the spacer and is separated into a bare bundle and grid region to maintain a manageable model size. An iterative process is used to couple the segregated flow domains to arrive at a converged solution. The grid spacer is a 7 x 7 mixing vane grid representative of an actual pressurized water reactor grid. Pressure drop and rod wall temperature predictions for steady-state operation are computed. The results show excellent agreement with experimental data. The agreement in these results demonstrates the usefulness of the method presented as a design tool for nuclear fuel manufacturers and as a prediction tool for off-design operating conditions such as simulated accident scenarios.

Campbell, Robert L.; Cimbala, John M.; Hochreiter, Lawrence E. [Pennsylvania State University (United States)

2005-01-15

319

An iterative CFD and mechanical brush seal model and comparison with experimental results  

SciTech Connect

The position of the bristles within a brush seal is dictated by the pressure distribution within the seal, which is itself influenced by the position of the bristle matrix. In order to predict mass flows, pressure capabilities, bristle displacements, stresses, and contact loads at the rotor interface, a technique for iterating between a CFD and a mechanical model has been developed. The iterative technique is used to model the behavior of seals with an initial build clearance, where the application of pressure causes a change in the position of the bristle matrix. Frictional effects between neighboring bristles and at the backing ring influence the behavior of the bristles and these are accounted for within the mechanical part of the model. Results are presented and discussed for seals of both initial build clearance and interference. The mathematical predictions for flow, contact loads at the rotor interface, and the nature of the bristles displacements are compared with experimental results.

Chen, L.H.; Wood, P.E.; Jones, T.V.; Chew, J.W.

1999-10-01

320

Experimental and calculational results from the Spent Fuel Test-Climax  

SciTech Connect

The Spent Fuel Test-Climax (SFT-C) is being conducted under the technical direction of the Lawrence Livermore National Laboratory for the US Department of Energy. The SFT-C is located 420 m below surface in the Climax placed in test storage in April and May 1980. At the same time, 6 electrical elevated-temperature phase of the test. Data related to heat transfer, thermomechanical response, radiation dose, and radiation damage have been collected and are presented here, as appropriate, with calculational results. In general, measured and calculated results compare well.

Patrick, W.C.; Ramspott, L.D.; Ballou, L.B.

1982-10-14

321

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

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…

Little, Priscilla M. D.; Harris, Erin

322

Experimental and Analytical Evaluation of a Composite Honeycomb Deployable Energy Absorber  

NASA Technical Reports Server (NTRS)

In 2006, the NASA Subsonic Rotary Wing Aeronautics Program sponsored the experimental and analytical evaluation of an externally deployable composite honeycomb structure that is designed to attenuate impact energy during helicopter crashes. The concept, which is designated the Deployable Energy Absorber (DEA), utilizes an expandable Kevlar honeycomb structure to dissipate kinetic energy through crushing. The DEA incorporates a unique flexible hinge design that allows the honeycomb to be packaged and stowed flat until needed for deployment. A variety of deployment options such as linear, radial, and/or hybrid methods can be used. Experimental evaluation of the DEA utilized a building block approach that included material characterization testing of its constituent, Kevlar -129 fabric/epoxy, and flexural testing of single hexagonal cells. In addition, the energy attenuation capabilities of the DEA were demonstrated through multi-cell component dynamic crush tests, and vertical drop tests of a composite fuselage section, retrofitted with DEA blocks, onto concrete, water, and soft soil. During each stage of the DEA evaluation process, finite element models of the test articles were developed and simulations were performed using the explicit, nonlinear transient dynamic finite element code, LS-DYNA. This report documents the results of the experimental evaluation that was conducted to assess the energy absorption capabilities of the DEA.

Jackson, Karen E.; Kellas, Sotiris; Horta, Lucas G.; Annett, Martin S.; Polanco, Michael A.; Littell, Justin D.; Fasanella, Edwin L.

2011-01-01

323

Experimental Limit on the Cosmic Diffuse Ultrahigh Energy Neutrino Flux  

Microsoft Academic Search

We report results from 120 hours of livetime with the Goldstone Lunar\\u000aUltra-high energy neutrino Experiment (GLUE). The experiment searches for <10\\u000ans microwave pulses from the lunar regolith, appearing in coincidence at two\\u000alarge radio telescopes separated by 22 km and linked by optical fiber. Such\\u000apulses would arise from subsurface electromagnetic cascades induced by\\u000ainteractions of >= 100

P. W. Gorham; C. L. Hebert; K. M. Liewer; C. J. Naudet; D. Saltzberg; D. Williams

2004-01-01

324

Drying in porous media with gravity-stabilized fronts: experimental results.  

PubMed

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

Yiotis, A G; Salin, D; Tajer, E S; Yortsos, Y C

2012-08-01

325

Drying in porous media with gravity-stabilized fronts: Experimental results  

NASA Astrophysics Data System (ADS)

In a recent paper [Yiotis , Phys. Rev. EPLEEE81539-375510.1103/PhysRevE.85.046308 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 Caf, Bond Bo, and Sherwood Sh numbers.

Yiotis, A. G.; Salin, D.; Tajer, E. S.; Yortsos, Y. C.

2012-08-01

326

D- sup 3 He fusion in the joint European torus tokamak; Recent experimental results  

SciTech Connect

This paper discusses a new series of D-{sup 3}He fusion yield experiments performed in the Joint European Torus (JET) using ion cyclotron resonance heating (ICRH) to generate a high-energy {sup 3}He tail reacting with a background deuterium plasma. Using recently installed antennas with beryllium screens, radio-frequency power reaching 15 MW can be coupled to the plasma at the fundamental cyclotron resonance of {sup 3}He near the magnetic axis. Best results are obtained with 3.5-MA discharges in the double-null configuration with high recycling on the outboard limiters to stay in L mode and to control the plasma density and purity. A record fusion power level of P{sub fus} = 140 kW is obtained, corresponding to a reaction rate of 4.6 {times} 10{sup 16} reaction/s. The amplification factor Q = P{sub fus}/P{sub ICRH} reaches a maximum of 1.25% at P{sub ICRH} = 10 MW. The previous best results were P{sub fus} = 100 kW and Q = 1%. Time-resolved measurements show a correlation between fusion power and energy stored in the fast {sup 3}He ions in agreement with calculations based on classical slowing down of the {sup 3}He ions driven by ICRH to an average energy in the mega-electron-volt range.

Jacquinot, J.; Sadler, G.J. (JET Joint Undertaking, Abingdon (United Kingdom))

1992-07-01

327

Noninvasive surface measurement of corrosion impedance of reinforcing bar in concrete - part 1: experimental results  

SciTech Connect

The corrosion state of a reinforcing steel bar in concrete can be characterized by the electrical impedance of the interface between the steel bar and the concrete. The experimental part of this study, has shown that changes in the interfacial impedance that are diagnostic of the rate and extent of the corrosion can be measured indirectly with an array of current and voltage electrodes on the concrete surface. The measured impedance, however depends on the electrical resistivity of the concrete, and the depth and diameter of the steel reinforcing bar as well as the interfacial properties. To relate the measured impedance directly to the interfacial properties, a closed-form solution to the governing Poisson's equation was developed and programmed for the potentials from arbitrary, current sources in the vicinity of the reinforcing bar. The solution uses an impedance boundary, condition for the complex impedance at the steel-concrete interface. The response of an arbitrary corrosion state can be simulated in this model by embedding the appropriate complex, frequency-dependent impedance at the interface and computing the voltage/current response that would be measured for an arbitrary placement of electrodes on the concrete surface. To simulate the experimental findings, this paper presents the modeling results by various interfacial impedances but constant concrete resistivity and constant geometry of the steel reinforcing bar This simulation confirms that important parameters of the interfacial impedance controlling corrosion kinetics such as polarization resistance and double layer capacitance are clearly, observed in the measured surface data. [References: 10

Zhang, Jieying; Monteiro, Paulo J.M.; Morrison, H. Frank

2000-11-01

328

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

NASA Astrophysics Data System (ADS)

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.

Gao, Bin

2014-05-01

329

Frequency-dependent seismic attenuation in shales: experimental results and theoretical analysis  

NASA Astrophysics Data System (ADS)

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.

Delle Piane, Claudio; Sarout, Joel; Madonna, Claudio; Saenger, Erik H.; Dewhurst, David N.; Raven, Mark

2014-07-01

330

Experimental results of flooding experiments in an inclined tube with liquid nitrogen and its vapor  

NASA Astrophysics Data System (ADS)

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%.

Chen, Jianye; Xu, Lu; Xiong, Wei; Qiu, Limin; Zhang, Xiaobin

2014-07-01

331

Frequency-dependent seismic attenuation in shales: experimental results and theoretical analysis  

NASA Astrophysics Data System (ADS)

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.

Delle Piane, Claudio; Sarout, Joel; Madonna, Claudio; Saenger, Erik H.; Dewhurst, David N.; Raven, Mark

2014-05-01

332

Preliminary results of the LLNL airborne experimental test-bed SAR system  

SciTech Connect

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.

Miller, M.G.; Mullenhoff, C.J.; Kiefer, R.D.; Brase, J.M.; Wieting, M.G.; Berry, G.L.; Jones, H.E.

1996-01-16

333

EASE (Experimental Assembly of Structures in EVA) overview of selected results  

NASA Technical Reports Server (NTRS)

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.

Akin, David L.

1987-01-01

334

Retained gas sampler extractor mixing and mass transfer rate study: Experimental and simulation results.  

National Technical Information Service (NTIS)

Research staff at Pacific Northwest National Laboratory conducted experimental testing and computer simulations of the impeller-stirred Retained Gas Sampler (RGS) gas extractor system. This work was performed to verify experimentally the effectiveness of ...

K. P. Recknagle J. M. Bates A. Shekarriz

1997-01-01

335

Results of Experiments on Convective Precipitation Enhancement in the Camaguey Experimental Area, Cuba.  

NASA Astrophysics Data System (ADS)

Experiments on randomized seeding of individual convective clouds and cloud clusters were conducted in the Camaguey experimental area, Cuba, from 1985 through 1990 in order to elucidate whether cold-cloud dynamic seeding can be used to augment convective rainfall. An information measuring system was set up, and primary tools included three instrumented aircraft (AN-26, AN-12 CYCLONE, IL-14), MRL-5 and ARS-3 radars, a system for radiosounding, two special rain gauge networks, and surface weather stations.A total of 232 randomized experiments were carried out during this experimentation period, and 117 individual clouds and 115 cloud clusters were studied during 136 `go' days. Pyrotechnic flares containing silver iodide were ejected in a selected cloud when the seeder aircraft was flying through its top. The seeding effects were monitored by the MRL-5 radar, which was equipped with an automated system for digital processing of data.A total of 46 convective clouds, 29 seeded and 17 nonseeded, were studied during an exploratory experiment in 1985. Analyses of the radar properties of seeded and nonseeded clouds have indicated that the response of convective clouds to AgI seeding is dependent on their type, and the treatment within the range of cloud tops from 6 to 8 km—that is, at top temperatures between 10° and 20°C, is found to increase their maximum height by 13% and the lifetime by 30%, and to enhance rainfall.A confirmatory phase of the experiment in the Camaguey experimental area was conducted during 1986 90. A total of 46 individual convective clouds, 24 seeded and 22 nonseeded, were identified, and their properties were determined using three-dimensional radar data. The results have shown that the AgI seeding of growing clouds with top temperatures over the range from 10° to 20°C increases their lifetime by 24%, maximum height by 9%, area by 64%, and rain volume by 120%, as compared to unseeded clouds. The lifetime, area, and rainfall results are significant at better than the 10% level using the Mann Whitney test.A total of 82 cluster cells, 42 seeded and 40 nonseeded, were studied. An analysis of stratified data has shown that as in the case of individual clouds, the greatest positive effect was achieved when treating the cells with top temperatures between 10° and 20°C. The seeding increased the lifetime by 21%, maximum cell height by 17%, maximum cell area by 28%, and rain volume by 65% at better than the 5% level.The results of cold-cloud dynamic seeding in Cuba are very consistent with those obtained in Florida, West Texas, and Thailand.

Koloskov, Boris; Zimin, Boris; Beliaev, Vitaly; Seregin, Yury; Chernikov, Albert; Petrov, Victor; Valdés, Mario; Martínez, Daniel; Pérez, Carlos A.; Puente, Guillermo

1996-09-01

336

Numerical Predictions and Experimental Results of Air Flow in a Smooth Quarter-Scale Nacelle  

SciTech Connect

Fires in aircraft engine nacelles must be rapidly suppressed to avoid loss of life and property. The design of new and retrofit suppression systems has become significantly more challenging due to the ban on production of Halon 1301 for environmental concerns. Since fire dynamics and the transport of suppressants within the nacelle are both largely determined by the available air flow, efforts to define systems using less effective suppressants greatly benefit from characterization of nacelle air flow fields. A combined experimental and computational study of nacelle air flow therefore has been initiated. Calculations have been performed using both CFD-ACE (a Computational Fluid Dynamics (CFD) model with a body-fitted coordinate grid) and WLCAN (a CFD-based fire field model with a Cartesian ''brick'' shaped grid). The flow conditions examined in this study correspond to the same Reynolds number as test data from the full-scale nacelle simulator at the 46 Test Wing. Pre-test simulations of a quarter-scale test fixture were performed using CFD-ACE and WLCAN prior to fabrication. Based on these pre-test simulations, a quarter-scale test fixture was designed and fabricated for the purpose of obtaining spatially-resolved measurements of velocity and turbulence intensity in a smooth nacelle. Post-test calculations have been performed for the conditions of the experiment and compared with experimental results obtained from the quarter-scale test fixture. In addition, several different simulations were performed to assess the sensitivity of the predictions to the grid size, to the turbulence models, and to the use of wall functions. In general, the velocity predictions show very good agreement with the data in the center of the channel but deviate near the walls. The turbulence intensity results tend to amplify the differences in velocity, although most of the trends are in agreement. In addition, there were some differences between WLCAN and CFD-ACE results in the angled wall regions due to the Cartesian grid structure used by the WLCAN code. Also, the experimental data tended t o show poorer resolution near the walls of the transition ducts. The increased uncertainty in the data highlights some of the challenges in getting data near the walls due to the low signal to noise ratio. Overall, this effort provided a benchmark case for both the WLCAN and CFD-ACE codes for the application of interest.

BLACK, AMALIA R.; SUO-ANTTILA, JILL M.; GRITZO, LOUIS A.; DISIMILE, PETER J.; TUCKER, JAMES R.

2002-06-01

337

Theoretical versus experimental results for the rotordynamic coefficients of eccentric, smooth, gas annular seal annular gas seals  

NASA Technical Reports Server (NTRS)

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.

Childs, Dara W.; Alexander, Chis

1994-01-01

338

Experimental results and first 22Na source image reconstruction by two prototype modules in coincidence of a liquid xenon positron emission tomograph for small animal imaging  

NASA Astrophysics Data System (ADS)

A detector with a very specific design using liquid Xenon (LXe) in the scintillation mode is studied for Positron Emission Tomography (PET) of small animals. Two prototype modules equipped with Position Sensitive Photo Multiplier Tubes (PSPMTs) operating in the VUV range (178 nm) and at 165 K were built and studied in coincidence. This paper reports on energy, time and spatial resolution capabilities of this experimental test bench. Furthermore, these experimental results were used to perform the first image reconstruction of a 22Na source placed in the experimental setup.

Gallin-Martel, M.-L.; Grondin, Y.; Gac, N.; Carcagno, Y.; Gallin-Martel, L.; Grondin, D.; Marton, M.; Muraz, J.-F.; Rossetto, O.; Vezzu, F.

2012-08-01

339

Experimental Study of Airfoil Trailing Edge Noise: Instrumentation, Methodology and Initial Results. M.S. Thesis  

NASA Technical Reports Server (NTRS)

The mechanisms of aerodynamic noise generation at the trailing edge of an airfoil is investigated. Instrumentation was designed, a miniature semiconductor strain-gauge pressure transducer and associated electronic amplifier circuitry were designed and tested and digital signal analysis techniques applied to gain insight into the relationship between the dynamic pressure close to the trailing edge and the sound in the acoustic far-field. Attempts are made to verify some trailing-edge noise generation characteristics as theoretically predicted by several contemporary acousticians. It is found that the noise detected in the far-field is comprised of the sum of many uncorrelated emissions radiating from the vicinity of the trailing edge. These emissions appear to be the result of acoustic energy radiation which has been converted by the trailing-edge noise mechanism from the dynamic fluid energy of independent streamwise 'strips' of the turbulent boundary layer flow.

Manley, M. B.

1980-01-01

340

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

SciTech Connect

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.

Nestler, B. [Institute of Applied Research, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133 Karlsruhe (Germany)]. E-mail: britta.nestler@fh-karlsruhe.de; Danilov, D. [Institute of Applied Research, Karlsruhe University of Applied Sciences, Moltkestrasse 30, 76133 Karlsruhe (Germany)]. E-mail: denis.danilov@fh-karlsruhe.de; Galenko, P. [Institute of Space Simulation, German Aerospace Center, 51170 Cologne (Germany)]. E-mail: peter.galenko@dlr.de

2005-07-20

341

Preliminary experimental results on studying possibility of variable mass liner (VML) formation  

SciTech Connect

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).

NONE

1995-12-31

342

Fracture mode analysis and related surface deformation during dyke intrusion: Results from 2D experimental modelling  

NASA Astrophysics Data System (ADS)

Surface deformation analysis in volcanic edifices in response to shallow magma intrusion is crucial for assessing volcanic hazards. In this paper, we discuss the effect of dyke propagation mode on surface deformation through 2D laboratory models. Our experimental setup consists of a Hele-Shaw cell, in which a model magma is injected into a cohesive model crust. Using an optical image correlation technique (Particle Imaging Velocimetry), we measured the surface deformation, the displacements and the strain field induced by magma emplacement within the country rock. We identify two types of intrusion morphologies (Types A and B), which exhibit two evolutional stages. During the first stage, both types resulted in a vertical dyke at depth; its propagation was controlled by both shear deformation and tensile opening. The model surface lifted up to form a smooth symmetrical dome, resulting in tensile cracks. During the second stage, Types A and B experiments differ when the dyke reaches a critical depth. In Type A, the intrusion gradually rotates, forming an inclined sheet dipping between 45° and 65°. This rotation results in asymmetrical surface uplift and shear failure upon the tip of the dyke. In Type B, the dyke tip interacts with tensile cracks formed during the first stage. This fracture controls the subsequent propagation of the dyke toward the surface. In both types of experiments, intrusions result in surface uplift, which can be accommodated by reverse faults. Our study suggests that dykes propagate as viscous indenters, rather than linear elastic fracturing.

Abdelmalak, M. M.; Mourgues, R.; Galland, O.; Bureau, D.

2012-12-01

343

Physical model and experimental results of cathode erosion related to power supply ripple  

NASA Technical Reports Server (NTRS)

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.

Harris, W. J.; O'Hair, E. A.; Hatfield, L. L.; Kristiansen, M.

1992-01-01

344

Topical drug delivery from thin applications: theoretical predictions and experimental results.  

PubMed

Stainless-steel templates of various thicknesses (75, 200, 800, and 1600 microns) were used to apply propylene glycol/water gels containing methyl or propyl p-aminobenzoates to silicone rubber membranes, and drug delivery was studied with the use of the Bronaugh diffusion cell under conditions in which the drug was initially in thermodynamic equilibrium with respect to the application and membrane. Theoretical diffusion profiles were generated with the use of a model which assumes that diffusional gradients exist within the application. To use the model equation, previously derived for the initial condition in which the drug is in thermodynamic equilibrium with respect to the application and membrane, drug diffusivity in both the application and the membrane and the drug's membrane/vehicle partition coefficient were independently determined. In general, agreement between experimental and theoretical results was within 25%. PMID:2281035

Addicks, W; Weiner, N; Flynn, G; Curl, R; Topp, E

1990-10-01

345

Reaction of Green River oil shale with radical-forming reagents: summary of experimental results  

SciTech Connect

A rich Green River Formation oil shale and derived materials have been subjected to solvent swelling and to radical-forming reagents. Some of the reacted shales from these experiments have been studied using Carbon-13 Nuclear Magnetic Resonance (/sup 13/C-NMR) Spectroscopy. Data from swelling experiments indicate the existence of a three-dimensional organic matrix. The reaction of shale organic matter with radical-forming reagents occurs under certain conditions, but does not result in large increases of bitumen yield. NMR studies indicate that some carbon-heteroatom bonds in the shale may be preferentially attacked by radical-forming species. One reagent, (2,2 azo-bis(2-methyl-propiononitrile)) (AIBN), may suppress coke formation when heated with shales. The attack by radicals on chemical bonds at kerogen-mineral interfaces could not be confirmed by the experimental data from this preliminary study. 6 refs., 6 figs., 4 tabs.

Branthaver, J.F.

1986-05-01

346

A scattering and absorption identity for metamaterials: Experimental results and comparison with theory  

NASA Astrophysics Data System (ADS)

A dispersion relation for the combined effect of scattering and absorption of electromagnetic waves is presented for a large class of linear and passive material models. By invoking the optical theorem, the result states that the extinction cross section integrated over all frequencies is equal to the static limit of the extinction volume. The present paper focuses on an attempt to experimentally verify this sum rule by measuring the monostatic radar cross section of a fabricated sample of metamaterial. In particular, the paper utilizes the idea that, for a specific class of targets, the scattered fields in the forward and backward directions are identical. It is concluded that the theoretical findings are in good agreement with measurements performed in the frequency range [3.2,19.5] GHz.

Sohl, C.; Larsson, C.; Gustafsson, M.; Kristensson, G.

2008-03-01

347

Verification test results of the experimental model coil for power system stabilization  

NASA Astrophysics Data System (ADS)

The authors are engaged in technological endeavors to create a coil at a drastically reduced cost with the aim of making it practical for SMES for power system stabilization. With focus on its novel conductor material and uniquely shaped coil, which were exclusively developed with the target of reducing the cost of the coil, an experimental model coil was devised. It is characterized by a single solenoid coil made of aluminum stabilized NbTi CIC. Experiments such as a rated 9.6 kA current-carrying test and current interrupting test were conducted to examine the performance of the model coil. The test results proved that the SMES model coil would perform as initially designed.

Terazono, K.; Hatabe, Y.; Kimura, H.; Hayashi, H.; Taniguchi, S.; Arika, M.; Semba, T.; Asano, K.; Ishii, T.; Ikeda, R.; Koso, S.; Tsuji, T.; Abe, H.; Tatsuta, Y.; Osaki, H.

2004-10-01

348

Prestress effects on the eigenfrequencies of the soundboards: experimental results on a simplified string instrument.  

PubMed

This paper presents an experimental study of the effects of prestresses on the vibration behavior of string instruments. These prestresses are created by gluing ribs (crowning) and tensioning string (downbearing). The effects of these prestresses were previously studied numerically for a piano soundboard by Mamou-Mani et al. [J. Acoust. Soc. Am. 123, 2401-2406 (2008)] and analytically for simplified models by Mamou-Mani et al. [Acta Acust. Unit. Acust. 95, 915-926 (2009)]. In the present study, a specified test bench is designed, including a simplified soundboard (a rectangular plate), a bridge, and a single string. The plate is subjected to in-plane and transverse loads. Vibrational eigenmodes are identified using nearfield acoustical holography (NAH) measurement. The evolution of eigenfrequencies with these specific prestresses is studied. The results show the effectiveness of NAH for this purpose and a very good qualitative concordance with previous numerical and analytical calculus. PMID:22280709

Mamou-Mani, Adrien; Le Moyne, Sylvie; Ollivier, François; Besnainou, Charles; Frelat, Joël

2012-01-01

349

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

SciTech Connect

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.

Pham, VT.; Silva, L.; Digonnet, H.; Combeaud, C.; Billon, N.; Coupez, T. [Centre for Material Forming (CEMEF), MINES ParisTech, Rue Claude Daunesse, Sophia Antipolis cedex (France)

2011-05-04

350

NACA 0012 benchmark model experimental flutter results with unsteady pressure distributions  

NASA Technical Reports Server (NTRS)

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 the program is to acquire measured dynamic instability and corresponding pressure data that will be useful for developing and evaluating aeroelastic type CFD 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.

Rivera, Jose A., Jr.; Dansberry, Bryan E.; Bennett, Robert M.; Durham, Michael H.; Silva, Walter A.

1992-01-01

351

NACA0012 benchmark model experimental flutter results with unsteady pressure distributions  

NASA Technical Reports Server (NTRS)

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.

Rivera, Jose A., Jr.; Dansberry, Bryan E.; Bennett, Robert M.; Durham, Michael H.; Silva, Walter A.

1992-01-01

352

Simulation and experimental results of optical and thermal modeling of gold nanoshells.  

PubMed

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±1.4nm are fabricated using co-precipitation method and subsequently covered by a thin layer of gold to obtain 15.8±3.5nm 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 11.98emu/g after coating with gold. The performance of the proposed optical-thermal modeling technique is verified by simulation and experimental results. PMID:25063109

Ghazanfari, Lida; Khosroshahi, Mohammad E

2014-09-01

353

Downstream evolution of turbulence from heated screens: Experimental and analytical results  

SciTech Connect

This report discusses recent efforts to characterize the flow and density nonuniformities downstream of heated screens placed in a uniform flow. The Heated Screen Test Facility (HSTF) at Sandia National Laboratories and the Lockheed Palo Alto Flow Channel (LPAFC) were used to perform experiments over wide ranges of upstream velocities and heating rates. Screens of various mesh configurations were examined, including multiple screens sequentially positioned in the flow direction. Diagnostics in these experiments included pressure manometry, hot-wire anemometry, interferometry, Hartmann wavefront slope sensing, and photorefractive schlieren photography. A model was developed to describe the downstream evolution of the flow and density nonuniformities. Equations for the spatial variation of the mean flow quantities and the fluctuation magnitudes were derived by incorporating empirical correlations into the equations of motion. Numerical solutions of these equations are in fair agreement with previous and current experimental results.

O'Hern, T.J.; Shagam, R.N.; Neal, D.R.; Suo-Anttila, A.J.; Torczynski, J.R.

1993-02-01

354

Active vibration absorber for CSI evolutionary model: Design and experimental results  

NASA Technical Reports Server (NTRS)

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.

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

1991-01-01

355

Noise characteristics of upper surface blown configurations. Experimental program and results  

NASA Technical Reports Server (NTRS)

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.

Brown, W. H.; Searle, N.; Blakney, D. F.; Pennock, A. P.; Gibson, J. S.

1977-01-01

356

Flapping counter torque (FCT) in animal flight: Experimental results and mathematical models  

NASA Astrophysics Data System (ADS)

From our previous studies on a range of insects from fruit flies to cockatoos during fast yaw turning maneuvers (body saccades), we found that body rotation causes a substantial aerodynamic counter torque, termed as flapping counter-torque (FCT), which acts in the opposite direction of turning. In this study, we show that FCT exists in all roll, pitch and yaw axes and are linearly dependent on the flapping frequency and rotational velocity, respectively. We measured the FCTs systematically (by varying wing beat frequency and body turning velocity) on a pair of dynamically scaled robotic model wings. Furthermore, we developed mathematical FCT models based on quasi-steady analysis for roll, pitch and yaw axes. The results show that the experimental data matches the prediction of the analytical models. FCT induced passive damping accounts for a large part of the deceleration in saccade of animal flight, and implies passive rotational stability of the angular velocity dynamics in flapping flight.

Cheng, Bo; Deng, Xinyan

2009-11-01

357

Continuous laser beam steering with micro-optical arrays: experimental results  

NASA Astrophysics Data System (ADS)

High resolution inertialess beam steering systems are required for numerous applications, including laser radar, multitarget designation or active imaging. We present a 1.55?m operating continuous laser beam steering system based on the cascading of an electro-optic PMN-PT ceramic optical phased array (OPA) and of two piezoactuated microlenses arrays (MLA). The function of the single devices and the principle and the operation of the combination of both are explained. Then we describe the experimental setup which was realized and outline the test results. The MLA large angle scanner consists of two MLAs, one of which can be moved with respect to the other by piezodrivers. This setup acts as a blazed grating and thus results in a discrete beam steering. Each steering position corresponds to a multiple of 2pi phase shift between adjacent beamlets. In order to get a continuous steering, we combined the MLA scanner with an electro-optic ceramic OPA. The OPA generates the piston distribution that compensates the phase difference between adjacent beamlets of the MLAs and reconstructs a continuous wavefront. The PMN-PT OPA consists in 64 phase modulators with 210µm period and a 0.5 fill factor. The maximum required voltage corresponding to the 2? phase shift is 150 Volts at 1.55µm. The OPA is imaged on the 105?m period MLAs with a 0.5-magnification telescope. The two MLAs are in a Keplerian telescope with field lenses arrangement. The steering performances of the MLAs alone are +/-12° scan angle with 28 discrete positions. Using the combined architecture, we were able to resolve 64 angular directions between each of these 28 positions. We thus experimentally obtained a continuous steering at 1.55?m over +/-12° with an angular resolution of 0.24mrad, i.e. 1800 resolved directions, with only 64+1 control voltages.

Bourderionnet, J.; Rungenhagen, M.; Dolfi, D.; Tholl, H. D.

2008-10-01

358

Using leg muscles as shock absorbers: theoretical predictions and experimental results of drop landing performance.  

PubMed

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

Minetti, A E; Ardigò, L P; Susta, D; Cotelli, F

1998-12-01

359

Experimental Results and Predictive Calculations for Pinhole Collimators Used in Small Animal Nuclear Imaging*  

NASA Astrophysics Data System (ADS)

Biological ligands tagged with ^125 I have been used in studies including comparisons between normal and diabetic mice in vivo. In order to enhance the image of the mouse pancreas we have tested a number of pinhole collimators coupled to two types of position sensitive photomultiplier tube. Various shapes of pinhole have been tested. Results will be described and discussed. *Supported in part by The Department of Energy, The National Science Foundation, The American Diabetes Association, The Howard Hughes Foundation, The Virginia Commonwealth Health Research Board and the Thomas F. and Kate Miller Jeffress Memorial Trust.

Ng, Luke; Welsh, Robert E.; Bradley, Eric L.; Saha, Margaret S.; Kross, Brian; Majewski, Stan; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Wojcik, Randolph

2001-04-01

360

Energy levels and quantum states of [Leu]enkephalin conformations based on theoretical and experimental investigations  

NASA Astrophysics Data System (ADS)

This paper describes a theoretical and experimental study of [Leu]enkephalin conformations with respect to the quantum states of the atomic structure of the peptide. Results from vibrational absorption measurements and quantum calculations are used to outline a quantum picture and to assign vibrational modes to the different conformations. The energy landscape of the conformations is reported as a function of a Hamming distance in Ramachandran space. Molecular dynamics simulations reveal a pronounced stability of the so-called single-bend low-energy conformation, which supports the derived quantum picture of this peptide.

Abdali, Salim; Jensen, Morten Ø.; Bohr, Henrik

2003-05-01

361

Shuttle Damage/Repair from the Perspective of Hypersonic Boundary Layer Transition - Experimental Results  

NASA Technical Reports Server (NTRS)

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 state of the boundary layer (laminar, transitional, or turbulent). Test parametrics include angles-of-attack of 30 deg and 40 deg, sideslip angle of 0 deg, freestream Reynolds numbers from 0.02x106 to 7.3x106 per foot, edge-to-wall temperature ratio from 0.4 to 0.8, and normal shock density ratios of approximately 5.3, 6.0, and 12 in Mach 6 air, Mach 10 air, and Mach 6 CF4, respectively. Testing to simulate the effects of ablation from a proposed tile repair concept indicated that transition was not a concern. The experimental protuberance and cavity databases highlighted in this report were used to formulate boundary layer transition correlations that were an integral part of an analytical process to disposition observed Orbiter TPS damage during STS- 114.

Horvath, Thomas J.; Berry, Scott A.; Merski, N. Ronald; Berger, Karen T.; Buck, Gregory M.; Liechty, Derek S.; Schneider, Steven P.

2006-01-01

362

An experimental investigation of multi-element airfoil ice accretion and resulting performance degradation  

NASA Technical Reports Server (NTRS)

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.

Potapczuk, Mark G.; Berkowitz, Brian M.

1989-01-01

363

An experimental investigation of multi-element airfoil ice accretion and resulting performance degradation  

NASA Technical Reports Server (NTRS)

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 for 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 past-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 measurements 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.

Potapczuk, Mark G.; Berkowitz, Brian M.

1989-01-01

364

Comparison Between Numerical and Experimental Results on Mechanical Stirrer and Bubbling in a Cylindrical Tank - 13047  

SciTech Connect

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)

Lima da Silva, M.; Sauvage, E.; Brun, P. [CEA-Marcoule, BP 17171, 30207 Bagnols sur Ceze (France)] [CEA-Marcoule, BP 17171, 30207 Bagnols sur Ceze (France); Gagnoud, A.; Fautrelle, Y. [SIMaP, Grenoble INP, UJF, CNRS, BP 75, 38402 Saint Martin D'Heres (France)] [SIMaP, Grenoble INP, UJF, CNRS, BP 75, 38402 Saint Martin D'Heres (France); Riva, R. [CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble (France)] [CEA-Grenoble, 17 rue des Martyrs, 38054 Grenoble (France)

2013-07-01

365

PROSPERO: online prediction of crystallographic success from experimental results and sequence.  

PubMed

The growth of diffracting crystals from purified proteins is often a major bottleneck in determining structures of biological and medical interest. The PROSPERO web server, http://skuld.bmsc.washington.edu/prospero, is intended both to provide a means of organizing the potentially large numbers of experimental characterizations measured from such proteins, and to provide useful guidance for structural biologists who have succeeded in purifying their target protein but have reached an impasse in the difficult and poorly understood process of turning purified protein into well diffracting crystals. These researchers need to decide which of many possible rescue options are worth pursuing, given finite resources. This choice is even more crucial when attempting to solve high-priority but relatively difficult structures of eukaryotic proteins. The site currently uses the HyGX1 predictor, which was trained and validated on protein samples from pathogenic protozoa (eukaryotes) using results from six types of experiment. PROSPERO allows users to store, analyze and display multiple results for each sample, to group samples into projects, and to share results and predictions with collaborators. PMID:22675232

Zucker, Frank H; Kim, Hae Young; Merritt, Ethan A

2012-06-01

366

Damping as a result of piezoelectric energy harvesting  

NASA Astrophysics Data System (ADS)

Systems that harvest or scavenge energy from their environments are of considerable interest for use in remote power supplies. A class of such systems exploits the motion or deformation associated with vibration, converting the mechanical energy to electrical, and storing it for later use; some of these systems use piezoelectric materials for the direct conversion of strain energy to electrical energy. The removal of mechanical energy from a vibrating structure necessarily results in damping. This research addresses the damping associated with a piezoelectric energy harvesting system that consists of a full-bridge rectifier, a filter capacitor, a switching DC-DC step-down converter, and a battery. Under conditions of harmonic forcing, the effective modal loss factor depends on: (1) the electromechanical coupling coefficient of the piezoelectric system; and (2) the ratio of the rectifier output voltage during operation to its maximum open-circuit value. When the DC-DC converter is maximizing power flow to the battery, this voltage ratio is very nearly 1/2, and the loss factor depends only on the coupling coefficient. Experiments on a base-driven piezoelectric cantilever, having a system coupling coefficient of 26%, yielded an effective loss factor for the fundamental vibration mode of 2.2%, in excellent agreement with theory.

Lesieutre, G. A.; Ottman, G. K.; Hofmann, H. F.

2004-01-01

367

Flow and thermodynamic characteristics of energy separation in a double-circuit vortex tube — An experimental investigation  

Microsoft Academic Search

Experimental investigations were made into the vortex energy separation effect of gas flux in tubes known as the Ranque effect. Technical applications of the results are considered. Unlike traditional energy separation tubes, so-called double-circuit vortex tubes were chosen that allowed the creation of a refrigeration device with high thermodynamic efficiency. Different thermodynamic and gas dynamical aspects of the processes taking

Sh. A. Piralishvili; V. M. Polyaev

1996-01-01

368

An experimental-finite element analysis on the kinetic energy absorption capacity of polyvinyl alcohol sponge.  

PubMed

Polyvinyl alcohol (PVA) sponge is in widespread use for biomedical and tissue engineering applications owing to its biocompatibility, availability, relative cheapness, and excellent mechanical properties. This study reports a novel concept of design in energy absorbing materials which consist in the use of PVA sponge as an alternative reinforcement material to enhance the energy loss of impact loads. An experimental study is carried out to measure the mechanical properties of the PVA sponge under uniaxial loading. The kinetic energy absorption capacity of the PVA sponge is computed by a hexahedral finite element (FE) model of the steel ball and bullet through the LS-DYNA code under impact load at three different thicknesses (5, 10, 15mm). The results show that a higher sponge thickness invokes a higher energy loss of the steel ball and bullet. The highest energy loss of the steel ball and bullet is observed for the thickest sponge with 160 and 35J, respectively. The most common type of traumatic brain injury in which the head subject to impact load causes the brain to move within the skull and consequently brain hemorrhaging. These results suggest the application of the PVA sponge as a great kinetic energy absorber material compared to commonly used expanded polystyrene foams (EPS) to absorb most of the impact energy and reduces the transmitted load. The results might have implications not only for understanding of the mechanical properties of PVA sponge but also for use as an alternative reinforcement material in helmet and packaging material design. PMID:24863223

Karimi, Alireza; Navidbakhsh, Mahdi; Razaghi, Reza

2014-06-01

369

Phase-space analysis and experimental results for secondary focusing at X-ray beamlines  

SciTech Connect

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.

Huang, Rong; Meron, Mati; Kujala, Naresh; Barrea, Raul A. (IIT); (UC); (HWMRI)

2011-11-17

370

Beryllium metal I. experimental results on acute oral toxicity, local skin and eye effects, and genotoxicity.  

PubMed

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 toxic properties. PMID:21196457

Strupp, Christian

2011-01-01

371

Beryllium Metal I. Experimental Results on Acute Oral Toxicity, Local Skin and Eye Effects, and Genotoxicity  

PubMed Central

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 toxic properties.

Strupp, Christian

2011-01-01

372

Experimental validation of a novel compact focusing scheme for future energy-frontier linear lepton colliders.  

PubMed

A novel scheme for the focusing of high-energy leptons in future linear colliders was proposed in 2001 [P. Raimondi and A. Seryi, Phys. Rev. Lett. 86, 3779 (2001)]. This scheme has many advantageous properties over previously studied focusing schemes, including being significantly shorter for a given energy and having a significantly better energy bandwidth. Experimental results from the ATF2 accelerator at KEK are presented that validate the operating principle of such a scheme by demonstrating the demagnification of a 1.3 GeV electron beam down to below 65 nm in height using an energy-scaled version of the compact focusing optics designed for the ILC collider. PMID:24484144

White, G R; Ainsworth, R; Akagi, T; Alabau-Gonzalvo, J; Angal-Kalinin, D; Araki, S; Aryshev, A; Bai, S; Bambade, P; Bett, D R; Blair, G; Blanch, C; Blanco, O; Blaskovic-Kraljevic, N; Bolzon, B; Boogert, S; Burrows, P N; Christian, G; Corner, L; Davis, M R; Faus-Golfe, A; Fukuda, M; Gao, J; García-Morales, H; Geffroy, N; Hayano, H; Heo, A Y; Hildreth, M; Honda, Y; Huang, J Y; Hwang, W H; Iwashita, Y; Jang, S; Jeremie, A; Kamiya, Y; Karataev, P; Kim, E S; Kim, H S; Kim, S H; Kim, Y I; Komamiya, S; Kubo, K; Kume, T; Kuroda, S; Lam, B; Lekomtsev, K; Liu, S; Lyapin, A; Marin, E; Masuzawa, M; McCormick, D; Naito, T; Nelson, J; Nevay, L J; Okugi, T; Omori, T; Oroku, M; Park, H; Park, Y J; Perry, C; Pfingstner, J; Phinney, N; Rawankar, A; Renier, Y; Resta-López, J; Ross, M; Sanuki, T; Schulte, D; Seryi, A; Shevelev, M; Shimizu, H; Snuverink, J; Spencer, C; Suehara, T; Sugahara, R; Takahashi, T; Tanaka, R; Tauchi, T; Terunuma, N; Tomás, R; Urakawa, J; Wang, D; Warden, M; Wendt, M; Wolski, A; Woodley, M; Yamaguchi, Y; Yamanaka, T; Yan, J; Yokoya, K; Zimmermann, F

2014-01-24

373

Experimental demonstration of energy-chirp compensation by a tunable dielectric-based structure.  

PubMed

A tunable energy-chirp compensator was used to remove a correlated energy chirp from the 60-MeV beam at the Brookhaven National Laboratory Accelerator Test Facility. The compensator operates through the interaction of the wakefield of the electron bunch with itself and consists of a planar structure comprised of two alumina bars with copper-plated backs separated by an adjustable beam aperture. By changing the gap size, the correlated energy chirp of the electron bunch was completely removed. Calculations show that this device, properly scaled to account for the electron bunch charge and length, can be used to remove residual correlated energy spread at the end of the linacs used for free-electron lasers. The experimental results are shown to be in good agreement with numerical simulations. Application of this technique can significantly simplify linac design and improve free-electron lasers performance. PMID:24702378

Antipov, S; Baturin, S; Jing, C; Fedurin, M; Kanareykin, A; Swinson, C; Schoessow, P; Gai, W; Zholents, A

2014-03-21

374

Experimental and theoretical high energy physics research. [UCLA  

SciTech Connect

Progress in the various components of the UCLA High-Energy Physics Research program is summarized, including some representative figures and lists of resulting presentations and published papers. Principal efforts were directed at the following: (I) UCLA hadronization model, PEP4/9 e{sup +}e{sup {minus}} analysis, {bar P} decay; (II) ICARUS and astroparticle physics (physics goals, technical progress on electronics, data acquisition, and detector performance, long baseline neutrino beam from CERN to the Gran Sasso and ICARUS, future ICARUS program, and WIMP experiment with xenon), B physics with hadron beams and colliders, high-energy collider physics, and the {phi} factory project; (III) theoretical high-energy physics; (IV) H dibaryon search, search for K{sub L}{sup 0} {yields} {pi}{sup 0}{gamma}{gamma} and {pi}{sup 0}{nu}{bar {nu}}, and detector design and construction for the FNAL-KTeV project; (V) UCLA participation in the experiment CDF at Fermilab; and (VI) VLPC/scintillating fiber R D.

Not Available

1992-01-01

375

General model with experimental validation of electrical resonant frequency tuning of electromagnetic vibration energy harvesters  

NASA Astrophysics Data System (ADS)

This paper presents a general model and its experimental validation for electrically tunable electromagnetic energy harvesters. Electrical tuning relies on the adjustment of the electrical load so that the maximum output power of the energy harvester occurs at a frequency which is different from the mechanical resonant frequency of the energy harvester. Theoretical analysis shows that for this approach to be feasible the electromagnetic vibration energy harvester’s coupling factor must be maximized so that its resonant frequency can be tuned with the minimum decrease of output power. Two different-sized electromagnetic energy harvesters were built and tested to validate the model. Experimentally, the micro-scale energy harvester has a coupling factor of 0.0035 and an untuned resonant frequency of 70.05 Hz. When excited at 30 mg, it was tuned by 0.23 Hz by changing its capacitive load from 0 to 4000 nF its effective tuning range is 0.15 Hz for a capacitive load variation from 0 to 1500 nF. The macro-scale energy harvester has a coupling factor of 552.25 and an untuned resonant frequency of 95.1 Hz and 95.5 Hz when excited at 10 mg and 25 mg, respectively. When excited at 10 mg, it was tuned by 3.8 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of 3.5 Hz for a capacitive load variation from 0 to 1200 nF. When excited at 25 mg, its resonant frequency was tuned by 4.2 Hz by changing its capacitive load from 0 to 1400 nF it has an effective tuning range of about 5 Hz. Experimental results were found to agree with the theoretical analysis to within 10%.

Zhu, Dibin; Roberts, Stephen; Mouille, Thomas; Tudor, Michael J.; Beeby, Stephen P.

2012-10-01

376

Performances and first experimental results of BACH, the beamline for dichroism and scattering experiments at ELETTRA  

NASA Astrophysics Data System (ADS)

BACH, the new soft x-ray beamline for polarization dependent experiments at the Italian synchrotron radiation facility ELETTRA, has been commissioned, characterized and opened to external users. Based on two APPLE II undulators, it covers an energy range between 35 eV and 1600 eV with the control of the light polarization. The monochromator works either in high resolution or high flux mode. Resolving powers of 16000 at 50 eV, 12000 at 90 eV, more than 12000 at 400 eV, 15000 at 534 eV and 6600 at 867 eV have been achieved with the three high resolution gratings. The resolving powers of the high flux grating, which covers the 290 - 1600 eV range, have been measured reaching 7000 at 400 eV and 2200 at 867 eV. The fluxes, in the high resolution mode, range between 4.1011 photons/s at 125 eV and 2.1010 photons/s at about 1100 eV. Using the high flux grating with the best resolution achievable 1.7.1011 photons/s impinge on the sample at 900 eV. Two branches are installed after the monochromator allowing the set-up of two different experimental stations. One of them, besides several facilities for surface preparation and analysis, hosts a compact inelastic soft x-ray spectrometer (ComIXS) dedicated to x-ray emission experiments exploiting the small spot (10 ?m in the vertical direction) on the sample. The other branch hosts a liquid helium cryostat equipped with a superconducting coil to perform absorption and transmission experiments with temperatures down to 2 K and magnetic field up to +/-7 T.

Zangrando, M.; Zacchigna, M.; Bondino, F.; Finazzi, M.; Pardini, T.; Platè, M.; Rochow, R.; Cocco, D.; Parmigiani, F.

2004-05-01

377

Oxygen diffusion in basalt and andesite melts: experimental results and discussion of chemical versus tracer diffusion  

NASA Astrophysics Data System (ADS)

Chemical diffusion coefficients for oxygen in melts of Columbia River basalt (Ice Harbor Dam flow) and Mt. Hood andesite have been determined at 1 atm. The diffusion model is that of sorption or desorption of oxygen into a sphere of uniform initial concentration from a constant and semi-infinite atmosphere. The experimental design utilizes a thermogravimetric balance to monitor the rate of weight change arising from the response of the sample redox state to an imposed fO2. Oxygen diffusion coefficients are approximately an order-ofmagnitude greater for basaltic melt than for andesitic melt. At 1260° C, the oxygen diffusion coefficients are: D=1.65×10-6cm2/s and D=1.43×10-7cm2/s for the basalt and andesite melts, respectively. The high oxygen diffusivity in basaltic melt correlates with a high ratio of nonbridging oxygen/tetrahedrally coordinated cations, low melt viscosity, and high contents of network-modifying cations. The dependence of the oxygen diffusion coefficient on temperature is: D=36.4exp(-51,600±3200/ RT)cm2/s for the basalt and D=52.5exp(-60,060±4900/ RT)cm2/s for the andesite ( R in cal/deg-mol; T in Kelvin). Diffusion coefficients are independent of the direction of oxygen diffusion (equilibrium can be approached from extremely oxidizing or reducing conditions) and thus, melt redox state. Characteristic diffusion distances for oxygen at 1260° C vary from 10-2 to 102 m over the time interval of 1 to 106 years. A compensation diagram shows two distinct trends for oxygen chemical diffusion and oxygen tracer diffusion. These different linear relationships are interpreted as supporting distinct oxygen transport mechanisms. Because oxygen chemical diffusivities are generally greater than tracer diffusivities and their Arrhenius activation energies are less, transport mechanisms involving either molecular oxygen or vacancy diffusion are favored.

Wendlandt, Richard F.

1991-10-01

378

Performances and first experimental results of BACH, the beamline for dichroism and scattering experiments at ELETTRA  

SciTech Connect

BACH, the new soft x-ray beamline for polarization dependent experiments at the Italian synchrotron radiation facility ELETTRA, has been commissioned, characterized and opened to external users. Based on two APPLE II undulators, it covers an energy range between 35 eV and 1600 eV with the control of the light polarization. The monochromator works either in high resolution or high flux mode. Resolving powers of 16000 at 50 eV, 12000 at 90 eV, more than 12000 at 400 eV, 15000 at 534 eV and 6600 at 867 eV have been achieved with the three high resolution gratings. The resolving powers of the high flux grating, which covers the 290 - 1600 eV range, have been measured reaching 7000 at 400 eV and 2200 at 867 eV. The fluxes, in the high resolution mode, range between 4{center_dot}1011 photons/s at 125 eV and 2{center_dot}1010 photons/s at about 1100 eV. Using the high flux grating with the best resolution achievable 1.7{center_dot}1011 photons/s impinge on the sample at 900 eV. Two branches are installed after the monochromator allowing the set-up of two different experimental stations. One of them, besides several facilities for surface preparation and analysis, hosts a compact inelastic soft x-ray spectrometer (ComIXS) dedicated to x-ray emission experiments exploiting the small spot (10 {mu}m in the vertical direction) on the sample. The other branch hosts a liquid helium cryostat equipped with a superconducting coil to perform absorption and transmission experiments with temperatures down to 2 K and magnetic field up to {+-}7 T.

Zangrando, M.; Zacchigna, M.; Bondino, F. [Laboratorio TASC-INFM, S.S. 14 Km 163.5 in Area Science Park, 34012 Trieste (Italy); Finazzi, M. [INFM - Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milan (Italy); Pardini, T. [Applied Physics department - Stanford University, 316 Via Pueblo Mall, Stanford, CA 94305 (United States); Plate, M. [Dipartimento di Fisica 'A. Volta', Universita di Pavia, Via Bassi 6, 27100 Pavia (Italy); Rochow, R.; Cocco, D. [Sincrotrone Trieste ScpA, S.S. 14 Km 163.5 in Area Science Park, 34012 Trieste (Italy); Parmigiani, F. [Laboratorio TASC-INFM, S.S. 14 Km 163.5 in Area Science Park, 34012 Trieste (Italy); Dipartimento di Matematica e Fisica, Universita Cattolica del Sacro Cuore, Via Musei 41, 25121 Brescia (Italy)

2004-05-12

379

Secondary emission from dust grains with a surface layer: comparison between experimental and model results  

NASA Astrophysics Data System (ADS)

The motion, coalescence, and other processes in dust clouds are determined by the dust charge. Since dust grains in the space are bombarded by energetic electrons, the secondary emission is an important process contributing to their charge. It is generally expected that the secondary emission yield is related to surface properties of the bombarded body. However, it is well known that secondary emission from small bodies is determined not only by their composition but an effect of dimension can be very important when the penetration depth of primary electrons is comparable with the grain size. It implies that the secondary emission yield can be influenced by the substrate material if the surface layer is thin enough. We have developed a simple Monte Carlo model of secondary emission that was successfully applied on the dust stimulants from glass and melamine formaldehyde (MF) resin and matched very well experimental results. In order to check the influence of surface layers, we have modified the model for spheres covered by a layer with different material properties. The results of model simulations are compared with measurements on MF spheres covered by a nickel layer.

Richterová, I.; Pavl?, J.; N?me?ek, Z.; Šafránková, J.; Žilavý, P.

2006-01-01

380

Not so simple: a quasi-experimental study of how researchers adjudicate genetic research results  

PubMed Central

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.

Hayeems, Robin Zoe; Miller, Fiona Alice; Li, Li; Bytautas, Jessica Peace

2011-01-01

381

Secondary emission from dust grains: Comparison of experimental and model results  

NASA Astrophysics Data System (ADS)

The motion, coalescence, and other processes in dust clouds are determined by the dust charge. Since dust grains in the space are bombarded by energetic electrons, the secondary emission is an important process contributing to their charge. It is generally expected that the secondary emission yield is related to surface properties of the bombarded body. However, it is well known that secondary emission from small bodies is determined not only by their composition but an effect of dimension can be very important when the penetration depth of primary electrons is comparable with the grain size. It implies that the secondary emission yield can be influenced by the substrate material if the surface layer is thin enough. We have developed a simple Monte Carlo model of secondary emission that was successfully applied on the dust simulants from glass and melanine formaldehyd (MF) resin and matched very well experimental results. In order to check the influence of surface layers, we have modified the model for spheres covered by a layer with different material properties. The results of model simulations are compared with measurements on MF spheres covered by different metals.

Richterova, I.; Pavlu, J.; Nemecek, Z.; Safrankova, J.; Zilavy, P.

382

Using the Viking biology experimental results to obtain chemical information about Martian regolith  

NASA Technical Reports Server (NTRS)

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.

Plumb, Robert C.

1992-01-01

383

A comparison of the theoretical and experimental results for keV electron scattering from argon  

NASA Astrophysics Data System (ADS)

Experiments studying the scattering of keV electrons from noble gas atoms have been performed in the past, as the first Born approximation (FBA) was thought to be valid under these conditions, and hence it was expected that these experiments could be modelled relatively straightforwardly by theory. Somewhat surprisingly these experiments have so far attracted only very limited theoretical interest and the ability of modern scattering theory to describe them has not been firmly established. In our earlier study of the cross section for the resonant transitions, we established that the FBA was sufficient to describe the results for small scattering angles, but it did not account for the observed intensity at larger angles. Here we extend this comparison for the case of argon to monopole, quadrupole and octopole transitions below the continuum. The experimental results show differential cross sections spanning many orders of magnitude for these transitions. The relativistic distorted wave theory developed here describes these experiments for many transitions and a large range of scattering angles reasonably well.

Vos, M.; McEachran, R. P.; Zhu, Lin-Fan

2014-03-01

384

Experimental energy resolution of a paracentric hemispherical deflector analyzer for different entry positions and bias.  

PubMed

A specially designed hemispherical deflector analyzer (HDA) with 5-element input lens having a movable entry position R0 suitable for electron energy analysis in atomic collisions was constructed and tested. The energy resolution of the HDA was experimentally determined for three different entry positions R0 = 84, 100, 112 mm as a function of the nominal entry potential V(R0) under pre-retardation conditions. The resolution for the (conventional) entry at the mean radius R0 = 100 mm was found to be a factor of 1.6-2 times worse than the resolution for the two (paracentric) positions R0 = 84 and 112 mm at particular values of V(R0). These results provide the first experimental verification and a proof of principle of the utility of such a paracentric HDA, while demonstrating its advantages over the conventional HDA: greater dispersion with reduced angular aberrations resulting in better energy resolution without the use of any additional fringing field correction electrodes. Supporting simulations of the entire lens plus HDA spectrometer are also provided and mostly found to be within 20%-30% of experimental values. The paracentric HDA is expected to provide a lower cost and?or more compact alternative to the conventional HDA particularly useful in modern applications utilizing a position sensitive detector. PMID:23635179

Dogan, M; Ulu, M; Gennarakis, G G; Zouros, T J M

2013-04-01

385

COMPARISON OF EXPERIMENTAL RESULTS TO CFD MODELS FOR BLENDING IN A TANK USING DUAL OPPOSING JETS  

SciTech Connect

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.

Leishear, R.

2011-08-07

386

Experimental and numerical study of cellulose-based electro-active paper energy harvester  

NASA Astrophysics Data System (ADS)

In this present study experimental and finite element analysis of cellulose based electro-active paper energy harvester is presented. Electro-active paper coated with metal electrode is a smart form of cellulose and exhibit piezoelectric effect. Specimens were prepared by depositing electrodes on both sides of the cellulose film. A 50 mm x 50 mm cellulose film coated with aluminum electrodes was bonded on 100 mm x 50 mm x 1 mm aluminum host structure. The voltage output to input acceleration frequency response across a load resistor of 1 M? is recorded by conventional energy harvesting experimental setup at the fundamental vibration mode of the EAPap cantilever beam. A coupled piezoelectric-circuit finite element model is developed in which load resistor is directly connected to energy scavenging device. Voltage output FRF is measured for the cases, without proof mass, and by adding a 2 grams proof mass near the tip of the cantilever. The experimental voltage FRF value is 7.6 V/g at 75.1 Hz and is improved to 13.8 V/g at 62.2 Hz when a stainless steel proof mass of 2 grams is added. The presented CPC-FEM model results agree reasonably well with the experimental results. Despite the fact that the electro-mechanical coupling coefficient of electro-active paper is lower than other available piezoelectric materials, it is biocompatible, cheap and naturally occurring polymeric material. It is also very flexible and posses similar piezoelectric characteristics such a PVDF which inspire to use EAPap in energy harvesting applications.

Abas, Zafar; Kim, Heung Soo; Zhai, Lindong; Kim, Jaehwan

2014-04-01

387

Numerical simulation of the amplification of picosecond laser pulses in tapered semiconductor amplifiers and comparison with experimental results  

NASA Astrophysics Data System (ADS)

We apply a traveling wave model to the simulation of the amplification of laser pulses generated by Q-switched or mode-locked distributed-Bragg reflector lasers. The power amplifier monolithically integrates a ridge-waveguide section acting as pre-amplifier and a flared gain-region amplifier. The diffraction limited and spectral-narrow band pulses injected in to the pre-amplifier have durations between 10 ps and 100 ps and a peak power of typical 1 W. After the amplifier, the pulses reach a peak power of several tens of Watts preserving the spatial, spectral and temporal properties of the input pulse. We report results obtained by a numerical solution of the traveling-wave equations and compare them with experimental investigations. The peak powers obtained experimentally are in good agreement with the theoretical predictions. The performance of the power amplifier is evaluated by considering the dependence of the pulse energy as a function of different device and material parameters.

Tronciu, V. Z.; Schwertfeger, S.; Radziunas, M.; Klehr, A.; Bandelow, U.; Wenzel, H.

2012-06-01

388

New experimental and simulated results on nuclear media effects in meson photoproduction off nuclei  

NASA Astrophysics Data System (ADS)

New experimental approach to study meson photoproduction in nuclei is discussed. It is based on the measurement of the recoil nucleon as a tagger for identification of the initial step of reaction. Propagation of mesons and nucleons within a nucleus is described by the Intra-Nuclear Cascade (INC) model. Simulations and preliminary experimental data for the deuteron target obtained at GRAAL are presented.

Ignatov, A.; Bartalini, O.; Bellini, V.; Bocquet, J. P.; Calvat, P.; Capogni, M.; Casano, M.; Castoldi, M.; D'Angelo, A.; Didelez, J.-P.; Di Salvo, R.; Fantini, A.; Gervino, G.; Ghio, F.; Girolami, B.; Giusa, A.; Guidal, M.; Hourany, E.; Kouznetsov, V.; Kunne, R.; Lapik, A.; Levi Sandri, P.; Lleres, A.; Moricciani, D.; Mushkarenkov, A.; Nedorezov, V.; Nicoletti, L.; Perrin, C.; Rebreyend, D.; Renard, F.; Rudnev, N.; Russew, T.; Russo, G.; Schaerf, C.; Sperduto, M.-L.; Sutera, M.-C.; Turinge, A.

2008-07-01

389

Experimental results and modeling techniques for substrate noise in mixed-signal integrated circuits  

Microsoft Academic Search

An experimental technique is described for observing the effects of switching transients in digital MOS circuits that perturb analog circuits integrated on the same die by means of coupling through the substrate. Various approaches to reducing substrate crosstalk (the use of physical separation of analog and digital circuits, guard rings, and a low-inductance substrate bias) are evaluated experimentally for a

David K. Su; Marc J. Loinaz; Shoichi Masui; Bruce A. Wooley

1993-01-01

390

Modal characterization of the ASCIE segmented optics testbed: New algorithms and experimental results  

NASA Technical Reports Server (NTRS)

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.

Carrier, Alain C.; Aubrun, Jean-Noel

1993-01-01

391

EXPERIMENTAL RESULTS ON TRAPPING A GUN PLASMA IN TORMAC P-l  

SciTech Connect

A start-up scheme for producing a plasma in the biscusp field configuration of TORMAC which involves the radial injection and trapping of a toroidal gun plasma is described. The peloidal field of the external cusp coils acts as a barrier to the outward travel of the plasma ring. Interferometry and magnetic probe measurements observed the stopping of the expanding plasma ring which has a velocity of 17 cm/{micro}sec. Once stopped, the fields are arranged to hold the plasma in a magnetic well. Interferometry measurements observed a well defined outer boundary remaining stationary during the 20 {micro}sec of the measurement. The inner boundary was also in evidence as shown particularly by the particle flux distribution emanating from the cusp region. The indications are that a sheath exists having a width of 1 to 1.5 ion gyro radii in the poloidial field. Measurements of Thomson and interferometry give a T{sub e} of 15eV, a 15 {micro}sec density decay time, and a 5 {micro}sec energy decay time. These results show that this injection and trapping method is successful, and thus a higher gun plasma energy combined with a flux conserving barrier may lead to higher temperatures for testing containment in TORMAC.

Pincosy, P.A.; Myers, B.R.; Levine, M.A.; Feinberg, B.; Niland, R.A.; Soroka, L.

1981-07-01

392

EXPERIMENTAL RESULTS ON TRAPPING A GUN PLASMA IN A TOROIDAL MAGNETIC CUSP EXPERIMENT  

SciTech Connect

A start-up method for producing a plasma in the bi-cusp field configuration of a toroidal magnetic cusp (TORMAC) is described. The method uses the radial injection and trapping of a toroidal gun plasma. Measurements of an injected plasma with a velocity of 17 {micro}sec{sup -1} and 4.5 x 10{sup 18} particles is presented. The plasma was observed to be stopped and trapped in an equilibrium position. A well-defined outer boundary remained stationary for 20 {micro}sec. Particle flux distribution emanating from the cusp field lines defined a sheath having a width of 1-1.5 ion gyroradii in the poloidial field. This translates to a narrow outer boundary and a broad inner boundary based on the gradient of the poloidial field at the two radial positions. Measurements of Thomson scattering and interferometry give a T{sub e} of 15eV, a 15 {micro}sec density decay time, and a 5 {micro}sec energy decay time. These results show that this injection and trapping method is successful, and thus a higher gun plasma energy combined with a flux conserving barrier may lead to higher temperatures for testing containment in TORMAC.

Pincosy, P.A.; Myers, B.R.; Levine, M.A.; Feinberg, B.; Niland, R.A.; Soroka, L.

1983-11-01

393

Infrared plus vacuum ultraviolet spectroscopy of neutral and ionic methanol monomers and clusters: new experimental results.  

PubMed

We present new observations of the infrared (IR) spectrum of neutral methanol and neutral and protonated methanol clusters employing IR plus vacuum ultraviolet (vuv) spectroscopic techniques. The tunable IR light covers the energy ranges of 2500-4500 cm(-1) and 5000-7500 cm(-1). The CH and OH fundamental stretch modes, the OH overtone mode, and combination bands are identified in the vibrational spectrum of supersonic expansion cooled methanol (2500-7500 cm(-1)). Cluster size selected IR plus vuv nonresonant infrared ion-dip infrared spectra of neutral methanol clusters, (CH(3)OH)(n) (n=2,[ellipsis (horizontal)],8), demonstrate that the methanol dimer has free and bonded OH stretch features, while clusters larger than the dimer display only hydrogen bonded OH stretch features. CH stretch mode spectra do not change with cluster size. These results suggest that all clusters larger than the dimer have a cyclic structure with OH groups involved in hydrogen bonding. CH groups are apparently not part of this cyclic binding network. Studies of protonated methanol cluster ions (CH(3)OH)(n)H(+) n=1,[ellipsis (horizontal)],7 are performed by size selected vuv plus IR photodissociation spectroscopy in the OH and CH stretch regions. Energies of the free and hydrogen bonded OH stretches exhibit blueshifts with increasing n, and these two modes converge to approximately 3670 and 3400 cm(-1) at cluster size n=7, respectively. PMID:17059254

Hu, Y J; Fu, H B; Bernstein, E R

2006-10-21

394

Storage-and-release flux rope eruptions in the laboratory: initial results and experimental plans  

NASA Astrophysics Data System (ADS)

Solar eruptive events such as coronal mass ejections (CMEs) are thought to be driven by a sudden release of magnetic energy stored in the corona. In many cases, the pre-eruptive configuration is a non-potential magnetic structure that can be modeled as a line-tied magnetic flux rope. In spite of ever-improving observational capabilities, directly studying the evolution of coronal flux ropes remains a significant challenge. Thus, in order to further explore the mechanisms that drive solar eruptions, we must find novel ways to simulate the relevant physical system. To this end, we have constructed a new laboratory experiment to study storage-and-release flux rope eruptions. This experiment contains a carefully designed set of ``sub-photospheric" coils that produces an active-region-like potential field configuration that remains static throughout the discharge. An arched magnetic flux rope plasma is formed within this potential field configuration by driving electric current through two line-tied footpoints (copper electrodes). Over the course of the discharge, the plasma current is quasi-statically increased (to tens of kiloamperes over many Alfvén times) in order to slowly build up magnetic energy in the system. As the flux rope gains energy, it will expand away from the electrodes to a point where it is expected to undergo a dynamic eruption due to the onset of a loss-of-equilibrium [Forbes & Isenberg, Astrophys. J. 373, 294 (1991)] or the torus instability [Kliem & Török, Phys. Rev. Lett. 96, 255002 (2006)]. In these experiments, the structure of the background potential field configuration (i.e., the field decay index) can be varied to study its effect on the observed flux rope eruptions. Initial results from these experiment are presented, including images from a fast visible light camera and direct measurements from internal magnetic diagnostics. This research is supported by DoE Contract Number DE-AC02-09CH11466 and by the Center for Magnetic Self-Organization (CMSO).; Specially designed magnetic field coils (orange and blue) are used to produce an active-region-like potential field configuration within the vacuum vessel (gray). An arched magnetic flux rope plasma is formed by driving electric current along low-lying potential field lines (blue/green). As magnetic energy builds up in the flux rope, it will expand outward and possibly undergo a storage-and-release eruption.

Myers, C. E.; Yamada, M.; Ji, H.; Yoo, J.; Jara-Almonte, J.; Lawrence, E. E.

2012-12-01

395

Experimental results for H2 formation from H- and H and implications for first star formation.  

PubMed

During the epoch of first star formation, molecular hydrogen (H2) generated via associative detachment (AD) of H- and H is believed to have been the main coolant of primordial gas for temperatures below 10(4) kelvin. The uncertainty in the cross section for this reaction has limited our understanding of protogalaxy formation during this epoch and of the characteristic masses and cooling times for the first stars. We report precise energy-resolved measurements of the AD reaction, made with the use of a specially constructed merged-beams apparatus. Our results agreed well with the most recent theoretically calculated cross section, which we then used in cosmological simulations to demonstrate how the reduced AD uncertainty improves constraints of the predicted masses for Population III stars. PMID:20595610

Kreckel, H; Bruhns, H; Cízek, M; Glover, S C O; Miller, K A; Urbain, X; Savin, D W

2010-07-01

396

MHD activity in the ISX-B tokamak: experimental results and theoretical interpretation  

SciTech Connect

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.

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

397

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

PubMed Central

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).

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

2012-01-01

398

First Experimental Results with a New Type of Stent: The Double-Coil Device  

SciTech Connect

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.

Strecker, Ernst-Peter [Diakonissenkrankenhaus Karlsruhe, Diakonissenstrasse 28, D-76199 Karlsruhe, Department of Diagnostic Imaging, Interventional Radiology and Nuclear Medicine (Germany)], E-mail: radiologie@diak-ka.de; Song, Ho-Young; Kang, Sung-Gwon [Asan Medical Center, University of Ulsan College of Medicine, Seoul, Department of Diagnostic Radiology (Korea, Republic of); Hou Dongming [Diakonissenkrankenhaus Karlsruhe, Diakonissenstrasse 28, D-76199 Karlsruhe, Department of Diagnostic Imaging, Interventional Radiology and Nuclear Medicine (Germany); Schumacher, M. [University Clinics Freiburg, Freiburg, Institute of Neuroradiology (Germany)

2003-06-15

399

A new mechanical device for circular compression anastomosis. Preliminary results of animal and clinical experimentation.  

PubMed Central

The authors report the preliminary results obtained in animal and clinical experimentation of a new mechanical device for circular anastomosis which they have developed. It is a gun that places an apparatus consisting of three polypropylene rings that, through the compression among them of the severed edges of the bowel, realize a sutureless anastomosis and are spontaneously evacuated. Fifty-eight colonic anastomoses were performed in dogs with this device; 23 stapled colonic anastomoses were also executed concurrently. Forty-four animals underwent a relaparotomy to remove the colonic specimen containing the anastomoses. Bursting pressure and the histologic features of the anastomoses were evaluated at different time intervals after operation. A good healing of all compression anastomoses was observed, thereby allowing them to initiate the experience in humans. Thirteen anastomoses (6 colorectal extraperitoneal, 1 colorectal intraperitoneal, 5 colocolonic, 1 ileorectal) were performed at the 1st Surgical Department, Milan University. One subclinical leakage (7.7%) spontaneously healed in a few days. No stenoses were observed. Images Fig. 1. Fig. 2., Fig. 4., Fig. 6. Fig. 3., Fig. 5., Fig. 7. Fig. 8. Fig. 9.

Rosati, R; Rebuffat, C; Pezzuoli, G

1988-01-01

400

Soil fumigation with chloropicrin in Italy: experimental results on melon, eggplant and tomato.  

PubMed

Starting in 1999, seven experimental trials were carried out in Italy in order to evaluate the efficacy of chloropicrin (CP) (Tripicrin, a.i. 99% by wt) as alternative to methyl bromide for soil disinfestation. CP applied by shank injection at 30-40 g/m2 provided a satisfactory and consistent control of Fusarium wilt on melon and Verticillium wilt on eggplant, particularly in sandy soils. On melon against Fusarium wilt and on tomato against F. radicis lycopersici and Fusarium and Verticillium wilts CP at 40 or 60 g/m2 applied by drip irrigation at the concentration of 400 to 700 microliters/l or 850 microliters/l provided the best results. CP applied at 80 g/m2 with 60 mm of water (corresponding to 850 microliters/l) did not increase the efficacy of the soil fumigation treatment and, on tomato, was phytotoxic, causing sudden collapse of plants immediately after the transplant. The comparison of chloropicrin drip application under polyethylene, widely used in the past for methyl bromide soil fumigation, or under virtually gas impermeable film (VIF), to reduce atmosphere emissions, showed an increase of CP efficacy under VIF only reducing the dosages below 40 or 30 g/m2. PMID:12701420

Gullino, M Lodovica; Minuto, Andrea; Garibaldi, Angelo

2002-01-01

401

Bioimaging and biospectra analysis by means of independent component analysis: experimental results  

NASA Astrophysics Data System (ADS)

Analysis of bioimaging and biospectra data has received increasingly attention in recent years. Here we will present two experimental results based on independent component analysis (ICA): differentiation of superparamagnetic iron oxide (SPIO) nanoparticles used as contrast agents in magnetic resonance imaging (MRI), and differentiation of mixed chemical analytes by surface-enhanced Raman scattering (SERS). The SPIO nanoparticles have been applied extensively as contrast agent in MRI for tracking of stem cells, targeted detection of cancer, due to its biocompatible and biodegradable features. For differentiation of SPIO from the background signal (e.g. interface between air and tissues), the signal voids from multiple sources makes the task very difficult. To solve this problem, we assume that the number of sensors corresponds to the number of acquisitions with different combinations of MR parameters, i.e., longitudinal and transverse relaxation times. For detection of chemical and biological analytes, the SERS approach has drawn more interest because of its high sensitivity. SERS spectra of mixed analytes were acquired at different locations of a silver nanorod array substrate. Due to the nonuniform diffusion and adsorption of the analytes, these spectra have been successfully used to identify the characteristic SERS spectrum of individual analytes. In both the MRI and SERS data, signal source separation (SPIO or mixed chemical analytes from background signal) was performed on a pixel by pixel basis. The ICA was performed by a spatial analysis using the fast ICA method.

Zhao, Qun; Langley, Jason; Lee, Joonsang; Abell, Justin; Zhao, Yiping

2011-05-01

402

Vibrational reduction in integral-damped composite fan blades: experimental results  

NASA Astrophysics Data System (ADS)

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.

Kosmatka, John B.; Mehmed, Oral

1998-06-01

403

Tubulin dipole moment, dielectric constant and quantum behavior: computer simulations, experimental results and suggestions.  

PubMed

We used computer simulation to calculate the electric dipole moments of the alpha- and beta-tubulin monomers and dimer and found those to be |p(alpha)| = 552D, |p(beta)| = 1193D and |p(alphabeta)| = 1740D, respectively. Independent surface plasmon resonance (SPR) and refractometry measurements of the high-frequency dielectric constant and polarizability strongly corroborated our previous SPR-derived results, giving Deltan/Deltac approximately 1.800 x 10(-3)ml/mg. The refractive index of tubulin was measured to be n(tub) approximately 2.90 and the high-frequency tubulin dielectric constant k(tub) approximately 8.41, while the high-frequency polarizability was found to be alpha(tub) approximately 2.1 x 10(-33)C m(2)/V. Methods for the experimental determination of the low-frequency p are explored, as well as ways to test the often conjectured quantum coherence and entanglement properties of tubulin. Biobits, bioqubits and other applications to bioelectronics are discussed. PMID:15527947

Mershin, A; Kolomenski, A A; Schuessler, H A; Nanopoulos, D V

2004-11-01

404

Experimental results of gain fluctuations and noise in microwave low-noise cryogenic amplifiers  

NASA Astrophysics Data System (ADS)

Applications like radio astronomy and space communications require ultimate sensitivity and make use of very particular receivers with state-of-the-art devices. Usually the receivers are cooled at cryogenic temperatures to reduce the noise even further. Noise temperatures of only a few times the quantum limit can be obtained in these conditions. During the past decade, Indium Phosphide HEMTs have demonstrated the best noise performance at cryogenic temperatures in the microwave frequency range of all active semiconductor devices, together with extremely low power consumption. For certain applications noise is not the only factor affecting the sensitivity. For example, gain fluctuations may play a dominant role in wide band radiometers. Unfortunately some of the factors that have contributed to improve the noise temperature have degraded the gain fluctuations. The operation at cryogenic temperatures also increases the fluctuations. This paper describes the experimental results obtained at the Centro Astronomico de Yebes (CAY) in the development of wide band cryogenic amplifiers. Special attention is paid to the influence of the bias point in noise and gain fluctuations. InP HEMTs from different foundries were tested. The amplifiers developed will be used in the Herschel ESA mission radiometers and the Atacama Large Millimeter Array (ALMA) receivers.

Gallego, Juan D.; López-Fernández, Isaac; Diez, Carmen; Barcia, Alberto

2004-05-01

405

A 2D optomechanical focused laser spot scanner: analysis and experimental results for microstereolithography  

NASA Astrophysics Data System (ADS)

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.

Gandhi, P. S.; Deshmukh, S.

2010-01-01

406

Unsteady pressures on a NACA 64A010 airfoil - Experimental and theoretical results  

NASA Technical Reports Server (NTRS)

Transonic testing of an NACA 64A010 airfoil at the Ohio State University Aero-Astro Research Laboratory is described, and results of fixed angle of attack and pitch oscillation experiments are discussed. The operating range was Mach 0.20 to 1.07 with available total pressures of 140,000 N/m2 to 620,000 N/m2. The airfoil model was mounted on roller bearings installed in the solid sidewalls of the tunnel test section. The equipment included transducers to measure unsteady pressures, and static pressure taps obtaining steady-state data. The data gathered at Mach 0.8 gave an indication of the influence of the natural shock instability and shock-induced flow separation on the unsteady pressures, with the location of the peak disturbance level shifting forward in the comparison of 0 to 2 deg pitch angle data. The oscillating airfoil data is examined in terms of harmonic content and the in-phase and out-of-phase components. It is concluded that the experimental data has good qualitative comparison with methods accounting for shock interaction.

Davis, J. A.; Petrie, S. L.

1979-01-01

407

UVA experimental and high energy physics. Final grant report  

SciTech Connect

The period 1992--1997 was a mixture of frustrations and of accomplishments for the UVa HEP group. The experimental HEP group began this period with the completion of a truncated run of Experiment E771 at Fermilab in 1992. This experiment was designed to measure the cross section for beauty production in 800 GeV/c pN interactions. It succeeded in this goal as well as in obtaining one of the best limits on FCNC in charm decays by setting an upper limit on D{sup 0} {r_arrow} {mu}{sup +}{mu}{sup {minus}}. In addition, they were able to measure {Psi}, {Psi}, {chi}{sub 1},{chi}{sub 2} and upsilon production. Three UVa PhD theses have resulted from this experiment (as well as 12 other PhD's at other institutions). At the same time, the UVa experimental group was vigorously pursuing the goal of studying CP violation in B production. This took the form of a proposal to the SSC for a super fixed target facility, the SFT, which would focus on studies of B mesons. B. Cox was the spokesman of this experiment that had over thirty institutions. This proposal EOI-14 had a good reception by the SSC PAC. A R and D activity to prove the technique of crystal channeling was undertaken to prove the accelerator aspects of this proposal. This activity, known as E853 or CEX at Fermilab, resulted in proof of the crystal channeling technique as viable for the extraction of 20 TeV beam at the SSC. In addition to this activity, the UVa group investigated many other aspects of B physics at the SSC. They were among the leaders of the 1993 Snowmass meeting on B Physics at Hadronic Accelerators. The UVa HEP group worked vigorously on developing the ideas for B physics at the SSC, as evidenced by the many different studies listed in the publication list given, up to the very day the SSC was terminated by an act of Congress.

Cox, B.

1999-10-07

408

Experimental Study of High-Energy Processing of Protoplanetary Materials  

NASA Astrophysics Data System (ADS)

The metal-silicate fractionation in celestial bodies effectively separates siderophile 182W from lithophile 182Hf into the core and mantle, respectively, making the Hf-W chronometer ideal for dating core-formation in differentiated planetary bodies. It is generally believed that there was equilibration of the Hf-W system during primary metal-silicate fractionation of small, initially chondritic, parent bodies. However, the accretion of larger objects like Moon and terrestrial planets generally involves giant impacts, with both the target and projectile probably being differentiated. Then, use of the Hf-W system assumes metal-silicate re-equilibration at high T and P while metal droplets rain through the magma ocean of a growing planet. Currently no experimental data at such conditions exist. Here we report the first results of experiments aimed at studying partitioning of Fe and Ni (proxy for W) between metal and silicate melt formed at high P and T by laser shocks of powered mixtures of pure Fe metal and Ni-bearing ALM-2 dunite. The initial targets with variable metal/dunite ratios were lightly pressed into 6.3 mm pellets (1-3 mm thick) and subjected to single laser pulses (~120-600 J, ~1 nsec). The details of experiments are described in the accompanying abstract by Remo et al. Some shots produced ~ 1 mm round craters in partially preserved targets which have been studied by optical microscopy, SEM and EPMA. The craters have rather rough surfaces and blackened appearance. The SEM images show thin (1-3 microns) films or pockets (3-8 microns) of silicate melt with or without tiny metal blebs which weld together angular grains of olivine and metal. The olivine contains no Al2O3 and ~0.4 wt% NiO; the metal is pure Fe. The melt, besides being lighter in the BSE images, shows distinct compositional differences (higher Al2O3 and FeO, lower MgO and SiO2) from olivine. The NiO content in metal-free melt films and pockets is similar to that in the host olivine. Metal in the metal-bearing melt pockets typically contains 0.2-0.7 wt% Ni and 0.6-1.5 wt% Si, while the NiO content in the silicate melt is close or below the EPMA detection limit of ~0.05 wt%. Thus, our results provide clear evidence for rapid extraction of Ni from silicate melt into metal on a timescale of microseconds. Chemical analyses and further experimental details will be reported at the meeting.

Petaev, M. I.; Jacobsen, S. B.; Remo, J. L.; Adams, R. G.; Sasselov, D. D.

2006-12-01

409

Acoustic propagation in the Hudson River Estuary: Analysis of experimental measurements and numerical modeling results  

NASA Astrophysics Data System (ADS)

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 Harbor observation and prediction system (NYHOPS) which provides 48-hour forecasts of salinity and temperature profiles. Initial results indicate that the NYHOPS forecast of sound speed profiles used in conjunction with the acoustic propagation model is able to make realistic forecasts of TL in the Hudson River Estuary.

Radhakrishnan, Sreeram

410

Sediment sorption coefficient measurements for four phthalate esters: Experimental results and model theory  

SciTech Connect

Sediment partition coefficients were measured for four commercial phthalate esters: dihexyl phthalate (DHP), di(2-ethylhexyl) phthalate (DEHP), diisodecyl phthalate (DIDP), and ditridecyl phthalate (DTDP). The experimental procedure was based on the US Environmental Protection Agency (EPA) test Guideline 796.2750, ``Sediment and Soil Adsorption Isotherm.`` Three sediments were used: EPA 8 (0.15% organic carbon), EPA 18 (0.66% organic carbon), and EPA 21 (1.88% organic carbon). The Freundlich equation was used to calculate organic carbon-normalized sediment/water partition coefficients (K{sub oc}), which averaged 5.26 {times} 10{sup 4} {+-} 4.54 {degree} 10{sup 3}; 4.82 {times} 10{sup 5} {+-} 3.52 {times} 10{sup 5}; 2.86 {times} 10{sup 5} {+-} 2.74 {times} 10{sup 5}; and 1.82 {times} 10{sup 6} {+-} 1.05 {times} 10{sup 6} for DHP, DEHP, DIDP, and DTDP, respectively. In general, these K{sub oc} values did not correlate well to either sediment or chemical properties. This lack of correlation suggested that the measured K{sub oc} values are suppressed, potentially as a function of experimental conditions. On the basis of these data, it was decided to investigate the dependence of K{sub oc} on sediment solids concentration and dissolved organic carbon. Analysis of these and earlier reported partition coefficient data indicated that measured K{sub oc} values for phthalate esters obtained in shake-flask experiments exhibited an inverse dependence on solids concentration. These results were consistent with partitioning models that are discussed. Depending on compound hydrophobicity, the particle-corrected K{sub oc} values were from one to three orders of magnitude higher than the measured K{sub oc} values. Therefore, if partition coefficient values obtained by using Test Guideline 796.2750 or similar shake-flask procedures are not corrected for solids effect, the estimates of the sediment pore-water concentration of the chemical is likely to be overestimated.

Williams, M.D.; Adams, W.J. [ABC Laboratories, Columbia, MO (United States); Parkerton, T.F.; Biddinger, G.R. [Exxon Biomedical Sciences, East Millstone, NJ (United States); Robillard, K.A. [Eastman Kodak Co., Rochester, NY (United States)

1995-09-01

411

Initial Experimental Results of a Laboratory Mini-Magnetosphere for Astronaut Protection  

NASA Astrophysics Data System (ADS)

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

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

412

Experimental and theoretical results on electron emission from helium by the impact of bare Li3+ ions  

NASA Astrophysics Data System (ADS)

We investigate experimentally and theoretically the ionization of helium atoms by the impact of bare Li3 + projectiles at intermediate and high incident energies. We report on measured absolute values of doubly differential cross-sections, as a function of the emitted electron energies and angles, at collision energies of 200 and 440 keV u-1. Different physical aspects of the reaction are interpreted theoretically by comparison of the data with quantum-mechanical continuum distorted wave and continuum distorted wave-eikonal initial state calculations as well as classical trajectory Monte Carlo simulations. There is an overall good agreement of the calculations with the experimental data, which improves considerably for higher collision energies.

Monti, J. M.; Fregenal, D.; Suárez, S.; Fainstein, P. D.; Rivarola, R. D.; Bernardi, G.; Fiol, J.

2012-07-01

413

Cabauw experimental results from the Project for Intercomparison of Land-Surface Parameterization Schemes  

USGS Publications Warehouse

In the Project for Intercomparison of Land-Surface Parameterization Schemes phase 2a experiment, meteorological data for the year 1987 from Cabauw, the Netherlands, were used as inputs to 23 land-surface flux schemes designed for use in climate and weather models. Schemes were evaluated by comparing their outputs with long-term measurements of surface sensible heat fluxes into the atmosphere and the ground, and of upward longwave radiation and total net radiative fluxes, and also comparing them with latent heat fluxes derived from a surface energy balance. Tuning of schemes by use of the observed flux data was not permitted. On an annual basis, the predicted surface radiative temperature exhibits a range of 2 K across schemes, consistent with the range of about 10 W m-2 in predicted surface net radiation. Most modeled values of monthly net radiation differ from the observations by less than the estimated maximum monthly observational error (±10 W m-2). However, modeled radiative surface temperature appears to have a systematic positive bias in most schemes; this might be explained by an error in assumed emissivity and by models' neglect of canopy thermal heterogeneity. Annual means of sensible and latent heat fluxes, into which net radiation is partitioned, have ranges across schemes of 30 W m-2 and 25 W m-2, respectively. Annual totals of evapotranspiration and runoff, into which the precipitation is partitioned, both have ranges of 315 mm. These ranges in annual heat and water fluxes were approximately halved upon exclusion of the three schemes that have no stomatal resistance under non-water-stressed conditions. Many schemes tend to underestimate latent heat flux and overestimate sensible heat flux in summer, with a reverse tendency in winter. For six schemes, root-mean-square deviations of predictions from monthly observations are less than the estimated upper bounds on observation errors (5 W m-2 for sensible heat flux and 10 W m-2 for latent heat flux). Actual runoff at the site is believed to be dominated by vertical drainage to groundwater, but several schemes produced significant amounts of runoff as overland flow or interflow. There is a range across schemes of 184 mm (40% of total pore volume) in the simulated annual mean root-zone soil moisture. Unfortunately, no measurements of soil moisture were available for model evaluation. A theoretical analysis suggested that differences in boundary conditions used in various schemes are not sufficient to explain the large variance in soil moisture. However, many of the extreme values of soil moisture could be explained in terms of the particulars of experimental setup or excessive evapotranspiration.

Chen, T. H.; Henderson-Sellers, A.; Milly, P. C. D.; Pitman, A. J.; Beljaars, A. C. M.; Polcher, J.; Abramopoulos, F.; Boone, A.; Chang, S.; Chen, F.; Dai, Y.; Desborough, C. E.; Dickinson, R. E.; Dumenil, L.; Ek, M.; Garratt, J. R.; Gedney, N.; Gusev, Y. M.; Kim, J.; Koster, R.; Kowalczyk, E. A.; Laval, K.; Lean, J.; Lettenmaier, D.; Liang, X.; Mahfouf, J. -F.; Mengelkamp, H. -T.; Mitchell, K.; Nasonova, O. N.; Noilhan, J.; Robock, A.; Rosenzweig, C.; Schaake, J.; Schlosser, C. A.; Schulz, J. -P.; Shao, Y.; Shmakin, A. B.; Verseghy, D. L.; Wetzel, P.; Wood, E. F.; Xue, Y.; Yang, Z. -L.; Zeng, Q.

1997-01-01