Minimum depth of investigation for grounded-wire TEM due to self-transients

NASA Astrophysics Data System (ADS)

Zhou, Nannan; Xue, Guoqiang

2018-05-01

The grounded-wire transient electromagnetic method (TEM) has been widely used for near-surface metalliferous prospecting, oil and gas exploration, and hydrogeological surveying in the subsurface. However, it is commonly observed that such TEM signal is contaminated by the self-transient process occurred at the early stage of data acquisition. Correspondingly, there exists a minimum depth of investigation, above which the observed signal is not applicable for reliable data processing and interpretation. Therefore, for achieving a more comprehensive understanding of the TEM method, it is necessary to perform research on the self-transient process and moreover develop an approach for quantifying the minimum detection depth. In this paper, we first analyze the temporal procedure of the equivalent circuit of the TEM method and present a theoretical equation for estimating the self-induction voltage based on the inductor of the transmitting wire. Then, numerical modeling is applied for building the relationship between the minimum depth of investigation and various properties, including resistivity of the earth, offset, and source length. It is guide for the design of survey parameters when the grounded-wire TEM is applied to the shallow detection. Finally, it is verified through applications to a coal field in China.

Turbulence measurements in a swirling confined jet flowfield using a triple hot-wire probe

NASA Technical Reports Server (NTRS)

Janjua, S. I.; Mclaughlin, D. K.

1982-01-01

An axisymmetric swirling confined jet flowfield, similar to that encountered in gas turbine combustors was investigated using a triple hot-wire probe. The raw data from the three sensors were digitized using ADC's and stored on a Tektronix 4051 computer. The data were further reduced on the computer to obtain time-series for the three instantaneous velocity components in the flowfield. The time-mean velocities and the turbulence quantities were deduced. Qualification experiments were performed and where possible results compared with independent measurements. The major qualification experiments involved measurements performed in a non-swirling flow compared with conventional X-wire measurements. In the swirling flowfield, advantages of the triple wire technique over the previously used multi-position single hot-wire method are noted. The measurements obtained provide a data base with which the predictions of turbulence models in a recirculating swirling flowfield can be evaluated.

Fluid dynamics and convective heat transfer in impinging jets through implementation of a high resolution liquid crystal technique

NASA Technical Reports Server (NTRS)

Kim, K.; Wiedner, B.; Camci, C.

1993-01-01

A combined convective heat transfer and fluid dynamics investigation in a turbulent round jet impinging on a flat surface is presented. The experimental study uses a high resolution liquid crystal technique for the determination of the convective heat transfer coefficients on the impingement plate. The heat transfer experiments are performed using a transient heat transfer method. The mean flow and the character of turbulent flow in the free jet is presented through five hole probe and hot wire measurements, respectively. The flow field character of the region near the impingement plate plays an important role in the amount of convective heat transfer. Detailed surveys obtained from five hole probe and hot wire measurements are provided. An extensive validation of the liquid crystal based heat transfer method against a conventional technique is also presented. After a complete documentation of the mean and turbulent flow field, the convective heat transfer coefficient distributions on the impingement plate are presented. The near wall of the impingement plate and the free jet region is treated separately. The current heat transfer distributions are compared to other studies available from the literature. The present paper contains complete sets of information on the three dimensional mean flow, turbulent velocity fluctuations, and convective heat transfer to the plate. The experiments also prove that the present nonintrusive heat transfer method is highly effective in obtaining high resolution heat transfer maps with a heat transfer coefficient uncertainty of 5.7 percent.

A Hot-Wire Method Based Thermal Conductivity Measurement Apparatus for Teaching Purposes

ERIC Educational Resources Information Center

Alvarado, S.; Marin, E.; Juarez, A. G.; Calderon, A.; Ivanov, R.

2012-01-01

The implementation of an automated system based on the hot-wire technique is described for the measurement of the thermal conductivity of liquids using equipment easily available in modern physics laboratories at high schools and universities (basically a precision current source and a voltage meter, a data acquisition card, a personal computer…

A debugging method of the Quadrotor UAV based on infrared thermal imaging

NASA Astrophysics Data System (ADS)

Cui, Guangjie; Hao, Qian; Yang, Jianguo; Chen, Lizhi; Hu, Hongkang; Zhang, Lijun

2018-01-01

High-performance UAV has been popular and in great need in recent years. The paper introduces a new method in debugging Quadrotor UAVs. Based on the infrared thermal technology and heat transfer theory, a UAV is under debugging above a hot-wire grid which is composed of 14 heated nichrome wires. And the air flow propelled by the rotating rotors has an influence on the temperature distribution of the hot-wire grid. An infrared thermal imager below observes the distribution and gets thermal images of the hot-wire grid. With the assistance of mathematic model and some experiments, the paper discusses the relationship between thermal images and the speed of rotors. By means of getting debugged UAVs into test, the standard information and thermal images can be acquired. The paper demonstrates that comparing to the standard thermal images, a UAV being debugging in the same test can draw some critical data directly or after interpolation. The results are shown in the paper and the advantages are discussed.

Memory alloy heat engine and method of operation

DOEpatents

Johnson, Alfred Davis

1977-01-01

A heat engine and method of operation employing an alloy having a shape memory effect. A memory alloy element such as one or more wire loops are cyclically moved through a heat source, along a path toward a heat sink, through the heat sink and then along another path in counter-flow heat exchange relationship with the wire in the first path. The portion of the wire along the first path is caused to elongate to its trained length under minimum tension as it is cooled. The portion of the wire along the second path is caused to contract under maximum tension as it is heated. The resultant tension differential between the wires in the two paths is applied as a force through a distance to produce mechanical work. In one embodiment a first set of endless memory alloy wires are reeved in non-slip engagement between a pair of pulleys which are mounted for conjoint rotation within respective hot and cold reservoirs. Another set of endless memory alloy wires are reeved in non-slip engagement about another pair of pulleys which are mounted in the respective hot and cold reservoirs. The pulleys in the cold reservoir are of a larger diameter than those in the hot reservoir and the opposite reaches of the wires between the two sets of pulleys extend in closely spaced-apart relationship in counter-flow heat regenerator zones. The pulleys are turned to move the two sets of wires in opposite directions. The wires are stretched as they are cooled upon movement through the heat regenerator toward the cold reservoirs, and the wires contract as they are heated upon movement through the regenerator zones toward the hot reservoir. This contraction of wires exerts a larger torque on the greater diameter pulleys for turning the pulleys and supplying mechanical power. Means is provided for applying a variable tension to the wires. Phase change means is provided for controlling the angular phase of the pulleys of each set for purposes of start up procedure as well as for optimizing engine operation under varying conditions of load, speed and temperatures.

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber.

PubMed

Schiffres, Scott N; Malen, Jonathan A

2011-06-01

A novel 3ω thermal conductivity measurement technique called metal-coated 3ω is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3ω exceeds alternate 3ω based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases), using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques, including transient hot-wire, steady-state methods, and solid-wire 3ω are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3ω was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity. © 2011 American Institute of Physics

Acquisition of Turbulence Data Using the DST Group Constant-Temperature Hot-Wire Anemometer System

DTIC Science & Technology

2015-10-01

fluctuations in the low-speed wind tunnel at DST Group. The use of both single- wire and crossed- wire (2 wire ) probes is described. Areas covered include a...fluid-flow studies, including testing of models of aircraft, ships and submarines in wind and water tunnels. Hot- wire anemometers and associated hot...spectra of velocity fluctuations in the low-speed wind tunnel at DST Group. The use of both single- wire and crossed- wire (2 wires ) probes is

Basic study on hot-wire flow meter in forced flow of liquid hydrogen

NASA Astrophysics Data System (ADS)

Oura, Y.; Shirai, Y.; Shiotsu, M.; Murakami, K.; Tatsumoto, H.; Naruo, Y.; Nonaka, S.; Kobayashi, H.; Inatani, Y.; Narita, N.

2014-01-01

Liquid hydrogen (LH2) is a key issue in a carbon-free energy infrastructure at the energy storage and transportation stage. The typical features of LH2 are low viscosity, large latent heat and small density, compared with other general liquids. It is necessary to measure a mass flow of liquid hydrogen with a simple and compact method, especially in a two phase separate flow condition. We have proposed applying a hot-wire type flow meter, which is usually used a for gas flow meter, to LH2 flow due to the quite low viscosity and density. A test model of a compact LH2 hot-wire flow meter to measure local flow velocities near and around an inside perimeter of a horizontal tube by resistance thermometry was designed and made. The model flow meter consists of two thin heater wires made of manganin fixed in a 10 mm-diameter and 40 mm-length tube flow path made of GFRP. Each rigid heater wire was set twisted by 90 degrees from the inlet to the outlet along the inner wall. In other words, the wires were aslant with regard to the LH2 stream line. The heated wire was cooled by flowing LH2, and the flow velocity was obtained by means of the difference of the cooling characteristic in response to the flow velocity. In this report, we show results on the basic experiments with the model LH2 hot-wire flow meter. First, the heat transfer characteristics of the two heater wires for several LH2 flow velocities were measured. Second, the heating current was controlled to keep the wire temperature constant for various flow velocities. The relations between the flow velocity and the heating current were measured. The feasibility of the proposed model was confirmed.

Method and apparatus for fabricating a thin-film solar cell utilizing a hot wire chemical vapor deposition technique

DOEpatents

Wang, Qi; Iwaniczko, Eugene

2006-10-17

A thin-film solar cell is provided. The thin-film solar cell comprises an a-SiGe:H (1.6 eV) n-i-p solar cell having a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer by hot wire chemical vapor deposition. A method for fabricating a thin film solar cell is also provided. The method comprises depositing a n-i-p layer at a deposition rate of at least ten (10) .ANG./second for the a-SiGe:H intrinsic layer.

Calibration, Data Acquisition, and Post Analysis of Turbulent Fluid Flow in a Calibration Jet Using Hot-wire Anemometry

NASA Technical Reports Server (NTRS)

Moreno, Michelle

2004-01-01

The Turbine Branch concentrates on the following areas: Computational Fluid Dynamics (CFD), and implementing experimental procedures to obtain physical modeling data. Hot-wire Anemometry is a valuable tool for obtaining physical modeling data. Hot-wire Anemometry is likely to remain the principal research tool for most turbulent air/gas flow studies. The Hot-wire anemometer consists of a fine wire heated by electric current. When placed in a fluid stream, the hot-wire loses heat to the fluid by forced convection. In forced convection, energy transfer is due to molecular motion imposed by an extraneous force moving fluid parcels. When the hot-wire is in "equilibrium", the rate of heat input to the wire is equal to the rate of heat loss at the wire ends. The equality between heat input and heat loss is the basis for King s equation, which relates the electrical parameters of the hot-wire to the flow parameters of the fluid. Hot-wire anemometry is based on convective heat transfer from a heated wire element placed in a fluid flow. Any change in the fluid flow condition that affects the heat transfer from the heated element will be detected virtually instantaneously by a constant-temperature Hot-wire anemometry system. The system implemented for this research is the IFA 300. The system is a fully-integrated, thermal anemometer-based system that measures mean and fluctuating velocity components in air, water, and other fluids. It also measures turbulence and makes localized temperature measurements. A constant-temperature anemometer is a bridge and amplifier circuit that controls a tiny wire at constant temperature. As a fluid flow passes over the heated sensor, the amplifier senses the bridge off-balance and adjusts the voltage to the top of the bridge, keeping the bridge in balance. The voltage on top of the bridge can then be related to the velocity of the flow. The bridge voltage is sensitive to temperature as well as velocity and so the built-in thermocouple circuit can be attached to a thermocouple that can measure the fluid temperature. Additional information is included in the original extended abstract.

Production and reactions of silicon atoms in hot wire deposition of amorphous silicon

NASA Astrophysics Data System (ADS)

Zheng, Wengang; Gallagher, Alan

2003-10-01

Decomposing silane and hydrogen molecules on a hot tungsten filament is an alternative method of depositing hydrogenated microcrystal and amorphous Si for thin-film semmiconductor devices. This "hot-wire" method can have significant advantages, such as high film deposition rates. The deposition chemistry involves Si and H atoms released from the filament, followed by their reactions with the vapor and surfaces. To establish these deposition pathways, we measure radicals at the substrate with a home built, threshold ionization mass spectrometer. The design and operation of this mass spectrometer for radical detection, and the behavior of Si atom production and reactions, will be presented. This work is supported by the National Renewable Energy Laboratory, Golden, CO 80401

Hot-Film and Hot-Wire Anemometry for a Boundary Layer Active Flow Control Test

NASA Technical Reports Server (NTRS)

Lenahan, Keven C.; Schatzman, David M.; Wilson, Jacob Samuel

2013-01-01

Unsteady active flow control (AFC) has been used experimentally for many years to minimize bluff-body drag. This technology could significantly improve performance of rotorcraft by cleaning up flow separation. It is important, then, that new actuator technologies be studied for application to future vehicles. A boundary layer wind tunnel was constructed with a 1ft-x-3ft test section and unsteady measurement instrumentation to study how AFC manipulates the boundary layer to overcome adverse pressure gradients and flow separation. This unsteady flow control research requires unsteady measurement methods. In order to measure the boundary layer characteristics, both hot-wire and hot-film Constant Temperature Anemometry is used. A hot-wire probe is mounted in the flow to measure velocity while a hot-film array lays on the test surface to measure skin friction. Hot-film sensors are connected to an anemometer, a Wheatstone bridge circuit with an output that corresponds to the dynamic flow response. From this output, the time varying flow field, turbulence, and flow reversal can be characterized. Tuning the anemometers requires a fan test on the hot-film sensors to adjust each output. This is a delicate process as several variables drastically affect the data, including control resistance, signal input, trim, and gain settings.

Comparison of Analysis, Simulation, and Measurement of Wire-to-Wire Crosstalk. Part 2

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Yavoich, Brian James; Hodson, Shane M.; Godley, Franklin

2010-01-01

In this investigation, we compare crosstalk analysis, simulation, and measurement results for electrically short configurations. Methods include hand calculations, PSPICE simulations, Microstripes transient field solver, and empirical measurement. In total, four representative physical configurations are examined, including a single wire over a ground plane, a twisted pair over a ground plane, generator plus receptor wires inside a cylindrical conduit, and a single receptor wire inside a cylindrical conduit. Part 1 addresses the first two cases, and Part 2 addresses the final two. Agreement between the analysis methods and test data is shown to be very good.

Numerical analysis of transient fields near thin-wire antennas and scatterers

NASA Astrophysics Data System (ADS)

Landt, J. A.

1981-11-01

Under the premise that `accelerated charge radiates,' one would expect radiation on wire structures to occur from driving points, ends of wires, bends in wires, or locations of lumped loading. Here, this premise is investigated in a series of numerical experiments. The numerical procedure is based on a moment-method solution of a thin-wire time-domain electric-field integral equation. The fields in the vicinity of wire structures are calculated for short impulsive-type excitations, and are viewed in a series of time sequences or snapshots. For these excitations, the fields are spatially limited in the radial dimension, and expand in spheres centered about points of radiation. These centers of radiation coincide with the above list of possible source regions. Time retardation permits these observations to be made clearly in the time domain, similar to time-range gating. In addition to providing insight into transient radiation processes, these studies show that the direction of energy flow is not always defined by Poynting's vector near wire structures.

Calibration and Measurement in Turbulence Research by the Hot-Wire Method

NASA Technical Reports Server (NTRS)

Kovasznay, Kaszlo

1947-01-01

The problem of turbulence in aerodynamics is at present being attacked both theoretically and experimentally. In view of the fact however that purely theoretical considerations have not thus far led to satisfactory results the experimental treatment of the problem is of great importance. Among the different measuring procedures the hot wire methods are so far recognized as the most suitable for investigating the turbulence structure. The several disadvantages of these methods however, in particular those arising from the temperature lag of the wire can greatly impair the measurements and may easily render questionable the entire value of the experiment. The name turbulence is applied to that flow condition in which at any point of the stream the magnitude and direction of the velocity fluctuate arbitrarily about a well definable mean value. This fluctuation imparts a certain whirling characteristic to the flow.

Insulation effect on thermal stability of Coated Conductors wires in liquid nitrogen

NASA Astrophysics Data System (ADS)

Rubeli, Thomas; Dutoit, Bertrand; Martynova, Irina; Makarevich, Artem; Molodyk, Alexander; Samoilenkov, Sergey

2017-02-01

Superconducting wires are not perfectly homogeneous in term of critical current as well as stabilization. In resistive fault current limiter applications this could lead to hot spots if the fault current is only slightly above the nominal current of the device. Increasing stabilization by using thicker silver coating for example may prevent this problem but this method implies longer wire length to maintain the same impedance during a fault. Very efficient cooling in another way to prevent hot spots, this can be achieved in nucleate boiling regime. Optimal insulation can be used to prevent film boiling regime, staying in nucleate boiling regime in a much broader temperature range. In this work a novel technique is used to monitor in real time the temperature of the wire during the quench. Using this method several increasing insulation thicknesses are tested, measuring for each the heat exchange rate to the nitrogen bath. Exchange rate measurements are made in quasistatic regime and during the re-cooling of the wire. SuperOx wires provided with different insulation thicknesses exhibit an excellent stability, far above a bare wire. On the other side, for very thick insulations the stability gain is lost. Re-cooling speeds dependency on insulation thicknesses is measured too.

Controlled rolling process for dual phase steels and application to rod, wire, sheet and other shapes

DOEpatents

Thomas, G.; Ahn, J.H.; Kim, N.J.

1986-10-28

An improved, energy efficient, hot rolling method for direct production of cold formable dual-phase steel is provided. The steel is heated to completely austenitize it and then continuously hot rolled and cooled down into the ferrite-austenite two phase region to a temperature which is just below the effective Ar[sub 3] temperature. The hot rolled steel is then rapidly quenched to provide an alloy containing strong, tough lath martensite (fibers) in a ductile soft ferrite matrix. The method is particularly useful for providing rods in which form the alloy is capable of being drawn into high strength wire or the like in a cold drawing operation without any intermediate annealing or patenting, and has excellent strength, ductility and fatigue characteristics. 3 figs.

Controlled rolling process for dual phase steels and application to rod, wire, sheet and other shapes

DOEpatents

Thomas, Gareth; Ahn, Jae-Hwan; Kim, Nack-Joon

1986-01-01

An improved, energy efficient, hot rolling method for direct production of cold formable dual-phase steel is provided. The steel is heated to completely austenitize it and then continuously hot rolled and cooled down into the ferrite-austenite two phase region to a temperature which is just below the effective Ar.sub.3 temperature. The hot rolled steel is then rapidly quenched to provide an alloy containing strong, tough lath martensite (fibers) in a ductile soft ferrite matrix. The method is particularly useful for providing rods in which form the alloy is capable of being drawn into high strength wire or the like in a cold drawing operation without any intermediate annealing or patenting, and has excellent strength, ductility and fatigue characteristics.

Hot-wire anemometry in hypersonic helium flow

NASA Technical Reports Server (NTRS)

Wagner, R. D.; Weinstein, L. M.

1974-01-01

Hot-wire anemometry techniques are described that have been developed and used for hypersonic-helium-flow studies. The short run time available dictated certain innovations in applying conventional hot-wire techniques. Some examples are given to show the application of the techniques used. Modifications to conventional equipment are described, including probe modifications and probe heating controls.

Critical Review of Industrial Techniques for Thermal-Conductivity Measurements of Thermal Insulation Materials

NASA Astrophysics Data System (ADS)

Hammerschmidt, Ulf; Hameury, Jacques; Strnad, Radek; Turzó-Andras, Emese; Wu, Jiyu

2015-07-01

This paper presents a critical review of current industrial techniques and instruments to measure the thermal conductivity of thermal insulation materials, especially those insulations that can operate at temperatures above and up to . These materials generally are of a porous nature. The measuring instruments dealt with here are selected based on their maximum working temperature that should be higher than at least . These instruments are special types of the guarded hot-plate apparatus, the guarded heat-flow meter, the transient hot-wire and hot-plane instruments as well as the laser/xenon flash devices. All technical characteristics listed are quoted from the generally accessible information of the relevant manufacturers. The paper includes rankings of the instruments according to their standard retail price, the maximum sample size, and maximum working temperature, as well as the minimum in their measurement range.

Thermal characterization of microscale heat convection in rare-gas environment by a steady-state “hot wire” method

NASA Astrophysics Data System (ADS)

Gao, Jianshu; Xie, Danmei; Xiong, Yangheng; Yue, Yanan

2018-06-01

In this work, a steady-state “hot wire” method is developed to study thermal transport around a microwire in a rare-gas environment. The convection heat transfer coefficient (h) around a 25 µm platinum wire is determined to be from 14 W m‑2 K‑1 at 7 Pa to 629 W m‑2 K‑1 at atmospheric pressure. In the free-molecule regime, the Nusselt number is found to be inversely proportional to the Knudsen number, the slope of which is used to determine the slip length as 7.03 × 10‑4 m. In the transition regime, the slip length is found to be 20 times the wire diameter. Under a certain pressure, h decreases with increasing wire temperature, and this trend is more sensitive at high pressures.

Methods of Measurement of High Air Velocities by the Hot Wire Method

DTIC Science & Technology

1943-02-01

to that of the heating current, as indicated by the minus sign. The cathode bias of the linearizing stage 1» then adjusted to obtain readings that...and tungsten wire. ! MM Taobaloai lot* lo. tifx» 3.- Heating aunnt of a bot «in at ooutaat-railitaae* operation. ? a UM tMMlMl nta Fe. IN nca . 4

Effect of rotation on a rotating hot-wire sensor

NASA Technical Reports Server (NTRS)

Hah, C.; Lakshminarayana, B.

1978-01-01

An investigation was conducted to discern the effects of centrifugal and Coriolis forces on a rotating hot-wire. The probe was calibrated in a wind tunnel as well as in a rotating mode. The effect of rotation was found to be negligibly small. A small change in cold resistance (1.5%) was observed in the rotating wire. The rotation seems to have a negligible effect on the fluid mechanics, heat transfer and material characteristics of the wire. This is a significant conclusion in view of the potential application of the hot-wire probe in a rotating passage (such as turbomachinery).

The 2d-LCA as an alternative to x-wires

NASA Astrophysics Data System (ADS)

Puczylowski, Jaroslaw; Hölling, Michael; Peinke, Joachim

2015-11-01

The 2d-Laser Cantilever Anemometer (2d-LCA) is an innovative sensor for two-dimensional velocity measurements in fluids. It uses a micostructured cantilever made of silicon and SU-8 as a sensing element and is capable of performing mesurements with extremly high temporal resolutions up to 150kHz. The size of the cantilever defines its spatial resolution, which is in the order of 150 μm only. Another big feature is a large angular range of 180° in total. The 2d-LCA has been developed as an alternative measurement method to x-wires with the motivation to create a sensor that can operate in areas where the use of hot-wire anemometry is difficult. These areas include measurements in liquids and in near-wall or particle-laden flows. Unlike hot-wires, the resolution power of the 2d-LCA does not decrease with increasing flow velocity, making it particularly suitable for measurements in high speed flows. Comparative measurements with the 2d-LCA and hot-wires have been carried out in order to assess the performance of the new anemometer. The data of both measurement techniques were analyzed using the same stochastic methods including a spectral analysis as well as an inspection of increment statistics and structure functions. Furthermore, key parameters, such as mean values of both velocity components, angles of attack and the characteristic length scales were determined from both data sets. The analysis reveals a great agreement between both anemometers and thus confirms the new approach.

2d-LCA - an alternative to x-wires

NASA Astrophysics Data System (ADS)

Puczylowski, Jaroslaw; Hölling, Michael; Peinke, Joachim

2014-11-01

The 2d-Laser Cantilever Anemometer (2d-LCA) is an innovative sensor for two-dimensional velocity measurements in fluids. It uses a micostructured cantilever made of silicon and SU-8 as a sensing element and is capable of performing mesurements with extremly high temporal resolutions up to 150 kHz. The size of the cantilever defines its spatial resolution, which is in the order of 150 μm only. Another big feature is a large angular range of 180° in total. The 2d-LCA has been developed as an alternative measurement method to x-wires with the motivation to create a sensor that can operate in areas where the use of hot-wire anemometry is difficult. These areas include measurements in liquids and in near-wall or particle-laden flows. Unlike hot-wires, the resolution power of the 2d-LCA does not decrease with increasing flow velocity, making it particularly suitable for measurements in high speed flows. Comparative measurements with the 2d-LCA and hot-wires have been carried out in order to assess the performance of the new anemometer. The data of both measurement techniques were analyzed using the same stochastic methods including a spectral analysis as well as an inspection of increment statistics and structure functions. Furthermore, key parameters, such as mean values of both velocity components, angles of attack and the characteristic length scales were determined from both data sets. The analysis reveals a great agreement between both anemometers and thus confirms the new approach.

MgB2 wire diameter reduction by hot isostatic pressing—a route for enhanced critical current density

NASA Astrophysics Data System (ADS)

Morawski, A.; Cetner, T.; Gajda, D.; Zaleski, A. J.; Häßler, W.; Nenkov, K.; Rindfleisch, M. A.; Tomsic, M.; Przysłupski, P.

2018-07-01

The effect of wire diameter reduction on the critical current density of pristine MgB2 wire was studied. Wires were treated by a hot isostatic pressing method at 570 °C and at pressures of up to 1.1 GPa. It was found that the wire diameter reduction induces an increase of up to 70% in the mass density of the superconducting cores. This feature leads to increases in critical current, critical current density, and pinning force density. The magnitude and field dependence of the critical current density are related to both grain connectivity and structural defects, which act as effective pinning centers. High field transport properties were obtained without doping of the MgB2 phase. A critical current density jc of 3500 A mm‑2 was reached at 4 K, 6 T for the best sample, which was a five-fold increase compared to MgB2 samples synthesized at ambient pressure.

Real-time monitoring of laser hot-wire cladding of Inconel 625

NASA Astrophysics Data System (ADS)

Liu, Shuang; Liu, Wei; Harooni, Masoud; Ma, Junjie; Kovacevic, Radovan

2014-10-01

Laser hot-wire cladding (LHWC), characterized by resistance heating of the wire, largely increases the productivity and saves the laser energy. However, the main issue of applying this method is the occurrence of arcing which causes spatters and affects the stability of the process. In this study, an optical spectrometer was used for real-time monitoring of the LHWC process. The corresponding plasma intensity was analyzed under various operating conditions. The electron temperature of the plasma was calculated for elements of nickel and chromium that mainly comprised the plasma plume. There was a correlation between the electron temperature and the stability of the process. The characteristics of the resulted clad were also investigated by measuring the dilution, hardness and microstructure.

On the measurement of turbulent fluctuations in high-speed flows using hot wires and hot films

NASA Technical Reports Server (NTRS)

Acharya, M.

1978-01-01

A hot wire has a limited life in high speed wind-tunnel flows because it is typically subjected to large dynamic loads. As a consequence hot films and modified hot wires are frequently used for turbulence measurements in such flows. However, the fluctuation sensitivities of such probes are reduced because of various factors, leading to erroneous results. This paper describes the results of tests on some sensors in both subsonic and supersonic boundary-layer flows. A simple technique to determine dynamic calibration correction factors for the sensitivities is also presented.

Comparison of Analysis, Simulation, and Measurement of Wire-to-Wire Crosstalk. Part 1

NASA Technical Reports Server (NTRS)

Bradley, Arthur T.; Yavoich, Brian James; Hodson, Shame M.; Godley, Richard Franklin

2010-01-01

In this investigation, we compare crosstalk analysis, simulation, and measurement results for electrically short configurations. Methods include hand calculations, PSPICE simulations, Microstripes transient field solver, and empirical measurement. In total, four representative physical configurations are examined, including a single wire over a ground plane, a twisted pair over a ground plane, generator plus receptor wires inside a cylindrical conduit, and a single receptor wire inside a cylindrical conduit. Part 1 addresses the first two cases, and Part 2 addresses the final two. Agreement between the analysis, simulation, and test data is shown to be very good.

A review of various nozzle range of wire arc spray on FeCrBMnSi metal coating

NASA Astrophysics Data System (ADS)

Purwaningsih, Hariyati; Rochiem, Rochman; Suchaimi, Muhammad; Jatimurti, Wikan; Wibisono, Alvian Toto; Kurniawan, Budi Agung

2018-04-01

Low Temperature Hot Corrosion (LTHC) is type of hot corrosion which occurred on 700-800°C and usually on turbine blades. So, as a result the material of turbine blades is crack and degredation of rotation efficiency. Hot corrosion protection with the use of barrier that separate substrate and environment is one of using metal surface coating, wire arc spray method. This study has a purpose to analyze the effect of nozzle distance and gas pressure on FeCrBMnSi coating process using wire arc spray method on thermal resistance. The parameter of nozzle distance and gas pressure are used, resulted the best parameter on distance 400 mm and gas pressure 3 bar which has the bond strength of 12,58 MPa with porosity percentage of 5,93% and roughness values of 16,36 µm. While the examination of thermal cycle which by heating and cooling continuously, on the coating surface is formed oxide compound (Fe3O4) which cause formed crack propagation and delamination. Beside that hardness of coating surface is increase which caused by precipitate boride (Fe9B)0,2

Corona evaluation for 270 volt dc systems

NASA Astrophysics Data System (ADS)

Dunbar, William G.

When designing 270 V dc power system electronics and wiring systems, it is essential to evaluate such corona-initiation-prone parts with bare electrodes as terminations and leads, and to take into account spacings, gas pressures (as a function of maximum altitude), temperature, voltage transients, and insulation coating thickness. Both persistent and intermittent transients are important. Filters and transient suppressors are excellent methods for limiting overvoltage transients in order to prevent corona initiation within a module.

Hot-wire Laser Welding of Deep and Wide Gaps

NASA Astrophysics Data System (ADS)

Näsström, J.; Frostevarg, J.; Silver, T.

Heavy section Gas Metal Arc Welding (GMAW) usually requires special edge preparation and several passes. One alternative for increased performance is Laser Arc Hybrid Welding (LAHW). For very thick sheets however, imperfections like root drops or solidification cracks can occur. In this study, other techniques are also studied, including multi-pass filling of deep gaps with wire deposition. A laser is then used to melt the filler and base material. The hot- and cold wire laser welding processes are highly sensitive to wire-laser positioning, where controlled melting of the wire is essential. Apart from a comprehensive literature survey, preliminary experiments were also performed in order to find a novel method variant that can successfully fill deep and wide gaps. The method applied uses a defocused laser that generates the melt pool. A resistance heated wire is fed into the melt pool front in a leading position. This is similar to additive manufacturing techniques such as laser direct metal deposition with wire. A layer height of several millimeters can be achieved and rather low laser power can be chosen. The preliminary experiments were observed using high speed imaging and briefly evaluated by visual examination of the resulting beads. Using a defocused laser beam turned out to have two major advantages; 1. It adds heat to the melt pool in a manner that properly fuses the bottom and walls of the base material. 2. It counteracts difficulties due to an irregularly oscillating filler wire. These early results show that this can be a promising technique for joining thick steels with wide gaps.

Investigation on two abnormal phenomena about thermal conductivity enhancement of BN/EG nanofluids.

PubMed

Li, Yanjiao; Zhou, Jing'en; Luo, Zhifeng; Tung, Simon; Schneider, Eric; Wu, Jiangtao; Li, Xiaojing

2011-07-09

The thermal conductivity of boron nitride/ethylene glycol (BN/EG) nanofluids was investigated by transient hot-wire method and two abnormal phenomena was reported. One is the abnormal higher thermal conductivity enhancement for BN/EG nanofluids at very low-volume fraction of particles, and the other is the thermal conductivity enhancement of BN/EG nanofluids synthesized with large BN nanoparticles (140 nm) which is higher than that synthesized with small BN nanoparticles (70 nm). The chain-like loose aggregation of nanoparticles is responsible for the abnormal increment of thermal conductivity enhancement for the BN/EG nanofluids at very low particles volume fraction. And the difference in specific surface area and aspect ratio of BN nanoparticles may be the main reasons for the abnormal difference between thermal conductivity enhancements for BN/EG nanofluids prepared with 140- and 70-nm BN nanoparticles, respectively.

New technique of skin embedded wire double-sided laser beam welding

NASA Astrophysics Data System (ADS)

Han, Bing; Tao, Wang; Chen, Yanbin

2017-06-01

In the aircraft industry, double-sided laser beam welding is an approved method for producing skin-stringer T-joints on aircraft fuselage panels. As for the welding of new generation aluminum-lithium alloys, however, this technique is limited because of high hot cracking susceptibility and strengthening elements' uneven distributions within weld. In the present study, a new technique of skin embedded wire double-sided laser beam welding (LBW) has been developed to fabricate T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys using eutectic alloy AA4047 filler wire. Necessary dimension parameters of the novel groove were reasonably designed for achieving crack-free welds. Comparisons were made between the new technique welded T-joint and conventional T-joint mainly on microstructure, hot crack, elements distribution features and mechanical properties within weld. Excellent crack-free microstructure, uniform distribution of silicon and superior tensile properties within weld were found in the new skin embedded wire double-sided LBW T-joints.

Transient and Sharvin resistances of Luttinger liquids

NASA Astrophysics Data System (ADS)

Kloss, Thomas; Weston, Joseph; Waintal, Xavier

2018-04-01

Although the intrinsic conductance of an interacting one-dimensional system is renormalized by the electron-electron correlations, it has been known for some time that this renormalization is washed out by the presence of the (noninteracting) electrodes to which the wire is connected. Here, we study the transient conductance of such a wire: a finite voltage bias is suddenly applied across the wire and we measure the current before it has enough time to reach its stationary value. These calculations allow us to extract the Sharvin (contact) resistance of Luttinger and Fermi liquids. In particular, we find that a perfect junction between a Fermi liquid electrode and a Luttinger liquid electrode is characterized by a contact resistance that consists of half the quantum of conductance in series with half the intrinsic resistance of an infinite Luttinger liquid. These results were obtained using two different methods: a dynamical Hartree-Fock approach and a self-consistent Boltzmann approach. Although these methods are formally approximate, we find a perfect match with the exact results of Luttinger/Fermi liquid theory.

Two-dimensional fringe probing of transient liquid temperatures in a mini space.

PubMed

Xue, Zhenlan; Qiu, Huihe

2011-05-01

A 2D fringe probing transient temperature measurement technique based on photothermal deflection theory was developed. It utilizes material's refractive index dependence on temperature gradient to obtain temperature information from laser deflection. Instead of single beam, this method applies multiple laser beams to obtain 2D temperature information. The laser fringe was generated with a Mach-Zehnder interferometer. A transient heating experiment was conducted using an electric wire to demonstrate this technique. Temperature field around a heating wire and variation with time was obtained utilizing the scattering fringe patterns. This technique provides non-invasive 2D temperature measurements with spatial and temporal resolutions of 3.5 μm and 4 ms, respectively. It is possible to achieve temporal resolution to 500 μs utilizing the existing high speed camera.

Hot wire anemometer measurements in the unheated air flow tests of the SRB nozzle-to-case joint

NASA Technical Reports Server (NTRS)

Ramachandran, N.

1988-01-01

Hot-Wire Anemometer measurements made in the Solid Rocket Booster (SRB) nozzle-to-case joint are discussed. The study was undertaken to glean additional information on the circumferential flow induced in the SRB nozzle joint and the effect of this flow on the insulation bonding flaws. The tests were conducted on a full-scale, 2-D representation of a 65-in long segment of the SRB nozzle joint, with unheated air as the working fluid. Both the flight Mach number and Reynolds number were matched simultaneously and different pressure gradients imposed along the joint face were investigated. Hot-wire anemometers were used to obtain velocity data for different joint gaps and debond configurations. The procedure adopted for hot-wire calibration and use is outlined and the results from the tests summarized.

Constant temperature hot wire anemometry data reduction procedure

NASA Technical Reports Server (NTRS)

Klopfer, G. H.

1974-01-01

The theory and data reduction procedure for constant temperature hot wire anemometry are presented. The procedure is valid for all Mach and Prandtl numbers, but limited to Reynolds numbers based on wire diameter between 0.1 and 300. The fluids are limited to gases which approximate ideal gas behavior. Losses due to radiation, free convection and conduction are included.

Laser Hot Wire Process: A Novel Process for Near-Net Shape Fabrication for High-Throughput Applications

NASA Astrophysics Data System (ADS)

Kottman, Michael; Zhang, Shenjia; McGuffin-Cawley, James; Denney, Paul; Narayanan, Badri K.

2015-03-01

The laser hot wire process has gained considerable interest for additive manufacturing applications, leveraging its high deposition rate, low dilution, thermal stability, and general metallurgical control including the ability to introduce and preserve desired meta-stable phases. Recent advancements in closed-loop process control and laser technology have increased productivity, process stability, and control of deposit metallurgy. The laser hot wire process has shown success in several applications: repairing and rejuvenating casting dies, depositing a variety of alloys including abrasion wear-resistant overlays with solid and tubular wires, and producing low-dilution (<5%) nickel alloy overlays for corrosion applications. The feasibility of fabricating titanium buildups is being assessed for aerospace applications.

The Analysis of Turbulent Flow by Hot Wire Signals. Ph.D. Thesis - Physikalische Ingenieurvissenschaft der Technischen Univ., 1981

NASA Technical Reports Server (NTRS)

Bartenwerfer, M.

1982-01-01

When measuring velocities in turbulent gas flow, approximation signal analysis with hot wire anemometers having one and two wire probes are used. A numeric test of standard analyses shows the resulting systemmatic error increases quickly with increasing turbulent intensity. Since it also depends on the turbulence structure, it cannot be corrected. The use of such probes is thus restricted to low turbulence. By means of three wire probes (in two dimensional flows with X wire probes) in principle, instantaneous values of velocity can be determined, and an asymmetric arrangement of wires has a theoretical advantage.

Selected physical properties of various diesel blends

NASA Astrophysics Data System (ADS)

Hlaváčová, Zuzana; Božiková, Monika; Hlaváč, Peter; Regrut, Tomáš; Ardonová, Veronika

2018-01-01

The quality determination of biofuels requires identifying the chemical and physical parameters. The key physical parameters are rheological, thermal and electrical properties. In our study, we investigated samples of diesel blends with rape-seed methyl esters content in the range from 3 to 100%. In these, we measured basic thermophysical properties, including thermal conductivity and thermal diffusivity, using two different transient methods - the hot-wire method and the dynamic plane source. Every thermophysical parameter was measured 100 times using both methods for all samples. Dynamic viscosity was measured during the heating process under the temperature range 20-80°C. A digital rotational viscometer (Brookfield DV 2T) was used for dynamic viscosity detection. Electrical conductivity was measured using digital conductivity meter (Model 1152) in a temperature range from -5 to 30°C. The highest values of thermal parameters were reached in the diesel sample with the highest biofuel content. The dynamic viscosity of samples increased with higher concentration of bio-component rapeseed methyl esters. The electrical conductivity of blends also increased with rapeseed methyl esters content.

Controlling an indirect hot water heater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Capano, J.

The procedure for servicing a Dunkirk Empire indirect water heater is presented. In this particular case the serviceman found that a wire was loose on the aquastat on the tank. The serviceman checked the wire and the past and tightened the connection. This took care of the problem. A wiring diagram is presented for the home heating system and the hot water heater.

Coupling device with improved thermal interface

NASA Astrophysics Data System (ADS)

Milam, Malcolm Bruce

1992-04-01

The primary object of the present invention is to provide a simple, reliable, and lightweight coupling that will also have an efficient thermal interface. A further object of the invention is to provide a coupling that is capable of blind mating with little or no insertion forces. Another object of the invention is to provide a coupling that acts as a thermal regulator to maintain a constant temperature on one side of the coupling. Another object of the invention is to increase the available surface area of a coupling thus providing a larger area for the conduction of heat across the thermal interface. Another object of the invention is to provide a fluidic coupling that has no fluid passing across the interface, thus reducing the likelihood of leaks and contamination. The foregoing objects are achieved by utilizing, as in the prior art, a hot area (at an elevated temperature as compared to a cold area) with a need to remove excess heat from the hot area to a cold area. In this device, the thermal interface will occur not on a planar horizontal surface, but along a non-planar vertical surface, which will reduce the reaction forces and increase the thermal conductivity of the device. One non-planar surface is a surface on a cold pin extending from the cold area and the other non-planar surface is a surface on a hot pin extending from the hot area. The cold pin is fixed and does not move while the hot pin is a flexible member and its movement towards the cold pin will bring the two non-planar surfaces together forming the thermal interface. The actuating member for the device is a shape-memory actuation wire which is attached through an aperture to the hot pin and through another aperture to an actuation wire retainer. By properly programming the actuation wire, heat from the hot area will cause the actuation wire to bend the hot wire. Heat from the hot area will cause the actuation wire to bend the hot pin towards the cold pin forming the coupling and the desired thermal interface. The shape-memory actuation wire is made of a shape-memory-effect alloy such as Nitinol.

Damping insert materials for settling chambers of supersonic wind tunnels

NASA Astrophysics Data System (ADS)

Wu, Jie; Radespiel, Rolf

2017-03-01

This study describes the application of a novel damping insert material for reducing the flow fluctuations in a tandem nozzle supersonic wind tunnel. This new damping material is composed of multi-layer stainless steel wired meshes. The influences of the multi-layer mesh, such as the quantity of the mesh layer and the installed location in the settling chamber, to the freestream quality have been investigated. A Pitot probe instrumented with a Kulite pressure sensor and a hot-wire probe are employed to monitor the flow fluctuation in the test section of the wind tunnel. Thereafter, a combined modal analysis is applied for the disturbance qualification. Additionally, the transient Mach number in the test section is measured. The disturbance qualification indicates that the multi-layer mesh performs well in providing reduction of vorticity reduction and acoustic fluctuations. Comparable flow quality of the freestream was also obtained using a combination of flexible damping materials. However, the life-span of the new damping materials is much longer. The time transient of the Mach number measured in the test section indicates that the mean flow is rather constant over run time. Furthermore, the time-averaged pressure along the settling chamber is recorded and it shows the distribution of pressure drop by settling chamber inserts.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wereszczak, Andrew A.; Emily Cousineau, J.; Bennion, Kevin

The apparent thermal conductivity of packed copper wire test specimens was measured parallel and perpendicular to the axis of the wire using laser flash, transient plane source, and transmittance test methods. Approximately 50% wire packing efficiency was produced in the specimens using either 670- or 925-μm-diameter copper wires that both had an insulation coating thickness of 37 μm. The interstices were filled with a conventional varnish material and also contained some remnant porosity. The apparent thermal conductivity perpendicular to the wire axis was about 0.5–1 W/mK, whereas it was over 200 W/mK in the parallel direction. The Kanzaki model andmore » an finite element analysis (FEA) model were found to reasonably predict the apparent thermal conductivity perpendicular to the wires but thermal conductivity percolation from nonideal wire-packing may result in their underestimation of it.« less

Anisotropic Thermal Response of Packed Copper Wire

DOE PAGES

Wereszczak, Andrew A.; Emily Cousineau, J.; Bennion, Kevin; ...

2017-04-19

The apparent thermal conductivity of packed copper wire test specimens was measured parallel and perpendicular to the axis of the wire using laser flash, transient plane source, and transmittance test methods. Approximately 50% wire packing efficiency was produced in the specimens using either 670- or 925-μm-diameter copper wires that both had an insulation coating thickness of 37 μm. The interstices were filled with a conventional varnish material and also contained some remnant porosity. The apparent thermal conductivity perpendicular to the wire axis was about 0.5–1 W/mK, whereas it was over 200 W/mK in the parallel direction. The Kanzaki model andmore » an finite element analysis (FEA) model were found to reasonably predict the apparent thermal conductivity perpendicular to the wires but thermal conductivity percolation from nonideal wire-packing may result in their underestimation of it.« less

"Grinding" cavities in polyurethane foam

NASA Technical Reports Server (NTRS)

Brower, J. R.; Davey, R. E.; Dixon, W. F.; Robb, P. H.; Zebus, P. P.

1980-01-01

Grinding tool installed on conventional milling machine cuts precise cavities in foam blocks. Method is well suited for prototype or midsize production runs and can be adapted to computer control for mass production. Method saves time and materials compared to bonding or hot wire techniques.

A comparison of calibration techniques for hot-wires operated in subsonic compressible slip flows

NASA Technical Reports Server (NTRS)

Jones, Gregory S.; Stainback, P. C.; Nagabushana, K. A.

1992-01-01

This paper focuses on the correlation of constant temperature anemometer voltages to velocity, density, and total temperature in the transonic slip flow regime. Three different calibration schemes were evaluated. The ultimate use of these hot-wire calibrations is to obtain fluctuations in the flow variables. Without the appropriate mean flow sensitivities of the heated wire, the measurements of these fluctuations cannot be accurately determined.

A comparison of disturbance levels measured in hypersonic tunnels using a hot-wire anemometer and a pitot pressure probe.

NASA Technical Reports Server (NTRS)

Stainback, P. C.; Wagner, R. D.

1972-01-01

Disturbance levels were measured in the test section of a Mach 5 blowdown jet using a constant-current, hot-wire anemometer and a pressure transducer. The disturbance levels, measured by the two instruments and normalized by local mean values, agreed within about 30%, with the pitot data higher than the hot-wire data. The rms disturbance levels measured with the hot-wire anemometer and converted to pitot pressures using a quasi-steady flow analysis, were about two-thirds the levels measured with the pitot probe. The variation of the normalized rms disturbance levels with stagnation pressure indicated that transition occurred in the boundary layer on the nozzle wall and influenced the outputs of the instruments located at the exit of the nozzle when the total pressure was about 35 N/sq cm. Below this pressure the disturbance levels decreased markedly. At higher pressures the disturbances were predominantly aerodynamic noise generated by the turbulent boundary layer on the nozzle wall.

Heating in short-pulse laser-driven cone-capped wire targets

NASA Astrophysics Data System (ADS)

Mason, R. J.; Wei, M.; King, J.; Beg, F.; Stephens, R. B.

2007-11-01

The 2-D implicit hybrid simulation code e-PLAS has been used to study heating in cone-capped copper wire targets. The code e-PLAS tracks collisional particle-in-cell (PIC) electrons traversing background plasma of collisional Eulerian cold electron and ion fluids. It computes E- and B-fields by the Implicit Moment Method [1,2]. In recent experiments [3] at the Vulcan laser facility, sub- picosecond laser pulses at 1.06 μm, and 4.0 x 10^20 W/cm^2 intensity were focused into thin-walled (˜10 μm) cones attached to copper wires. The wire diameter was varied from 10-40 μm with a typical length of 1 mm. We characterize heating of the wires as a function of their diameters and length, and relate modifications of this heating to changes in the assumed laser-generated hot electron spectrum and directivity. As in recent nail experiments [4], the cones can serve as reservoirs for hot electrons, diverting them from passage down the wires. [1] R. J. Mason, and C. Cranfill, IEEE Trans. Plasma Sci. PS-14, 45 (1986). [2] R. J. Mason, J. Comp. Phys. 71, 429 (1987). [3] J. King et al., to be submitted to Phys. Rev. Lett.. [4] R. J. Mason, M. Wei, F. Beg, R. Stephens, and C. Snell, in Proc. of ICOPS07, Albuquerque, NM, June 17-22, 2007, Talk 7D4.

Real-time monitoring of the laser hot-wire welding process

NASA Astrophysics Data System (ADS)

Liu, Wei; Liu, Shuang; Ma, Junjie; Kovacevic, Radovan

2014-04-01

The laser hot-wire welding process was investigated in this work. The dynamics of the molten pool during welding was visualized by using a high-speed charge-coupled device (CCD) camera assisted by a green laser as an illumination source. It was found that the molten pool is formed by the irradiation of the laser beam on the filler wire. The effect of the hot-wire voltage on the stability of the welding process was monitored by using a spectrometer that captured the emission spectrum of the laser-induced plasma plume. The spectroscopic study showed that when the hot-wire voltage is above 9 V a great deal of spatters occur, resulting in the instability of the plasma plume and the welding process. The effect of spatters on the plasma plume was shown by the identified spectral lines of the element Mn I. The correlation between the Fe I electron temperature and the weld-bead shape was studied. It was noted that the electron temperature of the plasma plume can be used to real-time monitor the variation of the weld-bead features and the formation of the weld defects.

Improvements of fabrication processes and enhancement of critical current densities in (Ba,K)Fe2As2 HIP wires and tapes

NASA Astrophysics Data System (ADS)

Pyon, Sunseng; Suwa, Takahiro; Tamegai, Tsuyoshi; Takano, Katsutoshi; Kajitani, Hideki; Koizumi, Norikiyo; Awaji, Satoshi; Zhou, Nan; Shi, Zhixiang

2018-05-01

We fabricated (Ba,K)Fe2As2 superconducting wires and tapes using the powder-in-tube method and hot isostatic pressing (HIP). HIP wires and tapes showed a high value of transport critical current density (J c) exceeding 100 kAcm‑2 at T = 4.2 K and the self-field. Transport J c in the HIP wire reached 38 kAcm‑2 in a high magnetic field of 100 kOe. This value is almost twice larger than the previous highest value of J c among round wires using iron-based superconductors. Enhancement of J c in the wires and tapes was caused by improvement of the drawing process, which caused degradation of the core, formation of microcracks, weak links between grains, and random orientation of grains. Details of the effect of the improved fabrication processes on the J c are discussed.

Low temperature junction growth using hot-wire chemical vapor deposition

DOEpatents

Wang, Qi; Page, Matthew; Iwaniczko, Eugene; Wang, Tihu; Yan, Yanfa

2014-02-04

A system and a process for forming a semi-conductor device, and solar cells (10) formed thereby. The process includes preparing a substrate (12) for deposition of a junction layer (14); forming the junction layer (14) on the substrate (12) using hot wire chemical vapor deposition; and, finishing the semi-conductor device.

Thermal degradation products from PVC film in food-wrapping operations.

PubMed

Boettner, E A; Ball, G L

1980-07-01

Thermal degradation products of polyvinyl chloride (PVC) food-wrap films were studied under simulated supermarket conditons using a commercial wrapping machine with either a hot wire or a cool rod cutting device. A sampling hood was constructed around the wire/rod to confine and allow collection of thermal degradation products produced. Compounds analyzed and normal concentration ranges found included hydrogen chloride (1-10 micrograms per cut), plasticizer (1-50 micrograms per cut), benzene and toluene (each < 5-20 ng per cut), acrolein (25-150 ng per cut), and carbon monoxide (2-4 micrograms per cut) using the hot wire. Room air samples, collected during hot-wire cutting without the sampling hood, had < 0.25 ppm hydrogen chloride. Using the cool-rod cutting device hydrogen chloride, benzene, and toluene were not detected. Plasticizer was detected (25-86 micrograms per cut) using the cool rod.

Amplification of Reynolds number dependent processes by wave distortion. [acoustic instability of liquid propellant rocket engines

NASA Technical Reports Server (NTRS)

Ventrice, M. B.; Fang, J. C.; Purdy, K. R.

1975-01-01

A system using a hot-wire transducer as an analog of a liquid droplet of propellant was employed to investigate the ingredients of the acoustic instability of liquid-propellant rocket engines. It was assumed that the combustion process was vaporization-limited and that the combustion chamber was acoustically similar to a closed-closed right-circular cylinder. Before studying the hot-wire closed-loop system (the analog system), a microphone closed-loop system, which used the response of a microphone as the source of a linear feedback exciting signal, was investigated to establish the characteristics of self-sustenance of acoustic fields. Self-sustained acoustic fields were found to occur only at resonant frequencies of the chamber. In the hot-wire closed-loop system, the response of hot-wire anemometer was used as the source of the feedback exciting signal. The self-sustained acoustic fields which developed in the system were always found to be harmonically distorted and to have as their fundamental frquency a resonant frequency for which there also existed a second resonant frequency which was approximately twice the fundamental frequency.

Sulfur Content Precision Control Technology for CO2-Shielded Welding Wire Steel

NASA Astrophysics Data System (ADS)

Chaofa, Zhang; Huaqiang, Hao; Youbing, Xiang; Shanxi, Liu

As a kind of impurity and displaying with FeS and MnS form in steel, Sulfur can make the disadvantage effect on the performance of hot-working, welding and corrosion resistance. The high content sulfur in steel can cause the hot brittle phenomenon for the steel. For the welding steel, when the sulfur content is higher, the drawing performance of wire rod become worst and the yield of wire rod decrease. When the sulfur is lower, the automatic wire feeding performance for the gas shielded welding become worst and the weld seam is not smooth. According to the results of welding expert research, 0.010%≤ S≤ 0.020% in CO2-shielded welding wire steel is reasonable.

Wind Tunnel Measurements of Turbulent Boundary Layer over Hypothetical Urban Roughness Elements

NASA Astrophysics Data System (ADS)

Ho, Y. K.; Liu, C. H.

2012-04-01

Urban morphology affects the near-ground atmospheric boundary layer that in turn modifies the wind flows and pollutant dispersion over urban areas. A number of numerical models (large-eddy simulation, LES and k-ɛ turbulence models) have been developed to elucidate the transport processes in and above urban street canyons. To complement the modelling results, we initiated a wind tunnel study to examine the influence of idealized urban roughness on the flow characteristics and pollutant dispersion mechanism over 2D idealized street canyons placed in cross flows. Hot-wire anemometry (HWA) was employed in this study to measure the flows over 2D street canyons in the wind tunnel in our university. Particular focus in the beginning stage was on the fabrication of hot-wire probes, data acquisition system, and signal processing technique. Employing the commonly adopted hot-wire universal function, we investigated the relationship in between and developed a scaling factor which could generalize the output of our hot-wire probes to the standardized one as each hot-wire probes has its unique behaviour. Preliminary experiments were performed to measure the wind flows over street canyons of unity aspect ratio. Vertical profiles of the ensemble average velocity and fluctuations at three different segments over the street canyons were collected. The results were then compared with our LES that show a good argument with each other. Additional experiments are undertaken to collect more data in order to formulate the pollutant dispersion mechanism of street canyons and urban areas.

Volume reduction of hot cell plastic wastes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dykes, F W; Henscheid, J P; Lewis, L C

1989-09-19

The disposal of radioactively-contaminated solid wastes has become a national crisis. In such circumstances, it is imperative that this waste be reduced to minimum volume and be packaged to prevent pollution of the environment. The majority of the solid waste generated at the hot cell under consideration is plastic lab ware. Cutting this waste into small pieces with a hot wire technique reduced the volume 66%. Melting the waste, although more time consuming, reduced the volume 90%. The hot wire technique can also be used to cut up damaged master slave manipulator boots, greatly reducing their disposal volume.

Transport of high intensity laser-generated hot electrons in cone coupled wire targets

NASA Astrophysics Data System (ADS)

Beg, Farhat

2008-04-01

In this talk, we present results from a series of experiments where cone-wire targets were employed both to assess hot electron coupling efficiency, and to reveal the source temperature of the hot electrons. Experiments were performed on the petawatt laser at the Rutherford Appleton Laboratory. A 500J, 1ps laser (I ˜ 4 x 10^20 W/cm-2) was focused by an f/3 off-axis parabolic mirror into hollow aluminum cones joined at their tip to Cu wires of diameters from 10 to 40 μm. The three main diagnostics fielded were a copper Kalpha Bragg crystal imager, a single hit CCD camera spectrometer and a Highly Oriented Pyrolytic Graphite (HOPG) spectrometer. The resulting data were cross-calibrated to obtain the absolute Kalpha yield. Comparison of the axially diminishing absolute Cu Kα intensity with modeling shows that the penetration of the hot electrons is consistent with one dimensional ohmic potential limited transport (1/e length ˜ 100 μm). The laser coupling efficiency to electron energy within the wire is shown to be proportional to the cross sectional area of the wire, reaching 15% for 40 μm wires. We find that the hot electron temperature within the wire was <=750 keV, significantly lower than that predicted by the ponderomotive scaling. A comparison of the experimental results with 2D hybrid PIC simulations using e-PLAS code will be presented and relevance to Fast Ignition will be discussed at the meeting. *In collaboration with J.A. King, M.H. Key, K.U. Akli, R.R. Freeman, J. Green, S. P. Hatchett, D. Hey, P. Jaanimagi, J. Koch, K. L. Lancaster, T. Ma, A.J. MacKinnon, A. MacPhee, R. Mason, P.A. Norreys, P.K Patel, T. Phillips, R. Stephens, W. Theobald, R.P.J. Town, M. Wei, L. Van Woerkom, B. Zhang.

78 FR 46303 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-31

... above, this [EASA] AD requires the installation of fuses in the power supply wiring and/or return wiring... revealed that, under certain failure conditions, wiring in the main fuel tank could develop a short circuit that might cause a hot spot on the wiring conduit or puncture the wiring conduit wall. This proposed AD...

Metallic hot wire anemometer. [for high speed wind tunnel tests

NASA Technical Reports Server (NTRS)

Lemos, F. R. (Inventor)

1977-01-01

A hot wire anemometer is described which has a body formed of heat resistant metal such as an alloy high in nickel content which supports a probe wire disposed in a V groove in the body. The V groove contains a high temperature ceramic adhesive that partially encompasses the downstream side of the probe wire. Mechanical and electrical connection to the probe wire is achieved through conductive support rods that are constructed of the same high temperature metal, insulation between the body and the conductor rods being provided by a coating of an oxide of the same material which coating is formed in situ. The oxide coating insulates the conductor rods from the body, mechanically fixes the conductors within the body, and maintains its integrity at elevated temperatures.

Simulation of the Vibratory Condition of the Compressor Blade with a Pressed wire Material “MR” Damper Which Located Around the Root Attachment

NASA Astrophysics Data System (ADS)

Gvozdev, Alexander S.; Melentjev, Vladimir S.

2018-01-01

When you create a modern gas turbine engines urgent task is to improve the reliability by preventing fatigue damages of rotor blades. Such damage is largely determined by the level of vibration stresses. In this paper, using the finite element method and transient analysis of propose a method calculating the damping characteristics of the plates of the pressed wire material “MR” around the root attachment of the compressor blades of a gas turbine engine. Where taken into account contact interaction between the blades and the impeller disk.

Measurement of Thermal Properties of Rocks at Temperature up to 1,000°C with Transient Plane Source Techniques

NASA Astrophysics Data System (ADS)

Kim, S. K.; Lee, Y.

2017-12-01

A set of devices that can measure thermal properties of rocks over a temperature range from room temperature up to 1,000°C with transient plane source techniques (also known as a Hot Disk method) is introduced. It consists of a main control system (e.g., TPS 2500 S from Hot Disk), mica-insulated sensor, tubular furnace, N2 gas supplier, and pressure regulator. The TPS 2500 S is the core instrument designed for precise analysis of thermal transport properties including thermal conductivity, thermal diffusivity, and volumetric heat capacity. The mica-insulated sensor is composed of an insulated nickel double spiral, which is utilized for both transient heating and precise temperature reading; a mica insulator protects the sensor against mechanical and thermal damage at high temperatures. The tubular furnace can hold two rock core samples of 50-mm-diameter and 25-mm-height with increasing temperatures up to 1,000°C. N2 gas supplier and pressure regulator are used to keep the inside the furnace away from oxygen. Thermal properties of most rocks and minerals vary with increasing temperatures. Experimental measurements of thermal properties at high temperatures have been made mostly using laser flash, needle probe, and divided bar methods in the previous researches, and no previous measurements with the Hot Disk method have been reported yet. We report thermal conductivities, thermal diffusivities, and volumetric heat capacities determined by a transient plane heat source method for fused silica and mafic rock samples using the introduced transient plane source apparatus. The thermal properties of fused silica have been measured mainly over the temperature range from ambient temperature to 500°C. The results seem to agree moderately with the previously reported values by Birch and Clark (Am. J. Sci., 1940). We now check the possible causes of measurement errors in our measurements and prepare to measure thermal properties of the mafic rock samples at temperatures up to 1,000°C using the hot disk method.

Thermophysical Properties of Matter - The TPRC Data Series. Volume 3. Thermal Conductivity - Nonmetallic Liquids and Gases

DTIC Science & Technology

1970-01-01

design and experimentation. I. The Shock- Tube Method Smiley [546] introduced the use of shock waves...one of the greatest disadvantages of this technique. Both the unique adaptability of the shock tube method for high -temperature measurement of...Line-Source Flow Method H. The Hot-Wire Thermal Diffusion Column Method I. The Shock- Tube Method J. The Arc Method K. The Ultrasonic Method .

A wavelet-based intermittency detection technique from PIV investigations in transitional boundary layers

NASA Astrophysics Data System (ADS)

Simoni, Daniele; Lengani, Davide; Guida, Roberto

2016-09-01

The transition process of the boundary layer growing over a flat plate with pressure gradient simulating the suction side of a low-pressure turbine blade and elevated free-stream turbulence intensity level has been analyzed by means of PIV and hot-wire measurements. A detailed view of the instantaneous flow field in the wall-normal plane highlights the physics characterizing the complex process leading to the formation of large-scale coherent structures during breaking down of the ordered motion of the flow, thus generating randomized oscillations (i.e., turbulent spots). This analysis gives the basis for the development of a new procedure aimed at determining the intermittency function describing (statistically) the transition process. To this end, a wavelet-based method has been employed for the identification of the large-scale structures created during the transition process. Successively, a probability density function of these events has been defined so that an intermittency function is deduced. This latter strictly corresponds to the intermittency function of the transitional flow computed trough a classic procedure based on hot-wire data. The agreement between the two procedures in the intermittency shape and spot production rate proves the capability of the method in providing the statistical representation of the transition process. The main advantages of the procedure here proposed concern with its applicability to PIV data; it does not require a threshold level to discriminate first- and/or second-order time-derivative of hot-wire time traces (that makes the method not influenced by the operator); and it provides a clear evidence of the connection between the flow physics and the statistical representation of transition based on theory of turbulent spot propagation.

Transition and turbulence measurements in hypersonic flows

NASA Technical Reports Server (NTRS)

Owen, F. K.

1990-01-01

This paper reviews techniques for transitional- and turbulent-flow measurements and describes current research in support of turbulence modeling. Special attention is given to the potential of applying hot wire and laser velocimeter to measuring turbulent fluctuations in hypersonic flow fields. The results of recent experiments conducted in two hypersonic wind tunnels are presented and compared with previous hot-wire turbulence measurements.

Hot flush frequency and severity at baseline as predictors of time to transient and stable treatment success: pooled analysis of two CE/BZA studies.

PubMed

Pinkerton, JoAnn V; Bushmakin, Andrew G; Bobula, Joel; Lavenberg, Joanne; Komm, Barry S; Abraham, Lucy

2017-12-01

To evaluate the impact of baseline hot flush frequency and severity on time to symptom improvement during treatment with conjugated estrogens/bazedoxifene (CE/BZA). Data were pooled through week 12 from two randomized placebo-controlled trials (SMART-1 and SMART-2) of nonhysterectomized postmenopausal women with hot flushes treated with CE 0.45 mg/BZA 20 mg or CE 0.625 mg/BZA 20 mg. Time to transient and stable improvement (≥ 50% reduction in hot flush frequency/severity) was estimated using nonparametric models. Transient improvement in hot flush frequency occurred earlier in women treated with CE 0.45 mg/BZA 20 mg with less frequent versus more frequent baseline hot flushes per day: median time to transient improvement was 2, 7, and 11 days for women with < 3, 3 to < 8, and ≥ 8 hot flushes per day at baseline, respectively (P = 0.0009). Transient improvement in severity occurred earlier for women with less severe versus more severe baseline hot flushes: median time to transient improvement was 2, 6, and 16 days for women with mild, moderate, and severe hot flushes at baseline, respectively (P < 0.0001). Stable improvement typically occurred 2 to 3 days after the transient event and was less influenced by baseline status. A similar pattern was observed with CE 0.625 mg/BZA 20 mg treatment, though improvement occurred a few days earlier than with CE 0.45 mg/BZA 20 mg. Women with more frequent/severe hot flushes take longer to achieve transient improvements with CE/BZA and should be encouraged to continue treatment, as it may take longer than a few weeks to achieve significant improvement.

Improvisation of mechanical and electrical properties of Cu by reinforcing MWCNT using modified electro-co-deposition process

NASA Astrophysics Data System (ADS)

Belgamwar, Sachin U.; Sharma, N. N.

2018-04-01

Multi-walled Carbon nanotubes–copper (MWCNT/Cu) composite powders with variable MWCNT content were synthesized by modified electro-co-deposition method. The electro-co-deposited MWCNT/Cu powders were consolidated by conventional compaction and sintering process. The consolidated products were then hot rolled and cold drawn to fine wires. The MWCNT/Cu composite wire samples were characterized for electrical and mechanical properties. We have been able to achieve an increase of around 8% in electrical conductivity of the form wires repeatedly. It has been observed that there was gradual improvement in the properties with reinforcement of MWCNT in the copper matrix. The betterment of electrical property has been achieved with simultaneous improvement in mechanical properties of the wire. The yield strength of MWCNT/Cu composite wire was found to be four times and the tensile strength two times greater than that of pure copper. The improved properties are attributed to the proper distribution of MWCNTs in the copper matrix and excellent interfacial bonding between MWCNT and composite copper fabricated by the modified method.

A nonperturbing boundary-layer transition detection

NASA Astrophysics Data System (ADS)

Ohare, J. E.

1985-01-01

A laser interferometer technique is being applied to the characterization of boundary-layer conditions on models in supersonic and hypersonic wind tunnels in the von Karman Facility at Arnold Engineering Development Center (AEDC). The Boundary-Layer Transition Detector (BLTD), based on lateral interferometry, is applicable for determining the turbulence frequency spectrum of boundary layers in compressible flow. The turbulence, in terms of air density fluctuations, is detected by monitoring interferometric fringe phase shifts (in real time) formed by one beam which passes through the boundary layer and a reference beam which is outside the boundary layer. This technique is nonintrusive to the flow field unlike other commonly used methods such as pitot tube probing and hot-wire anemometry. Model boundary-layer data are presented at Mach 8 and compared with data recorded using other methods during boundary-layer transition from laminar to turbulent flow. Spectra from the BLTD reveal the presence of a high-frequency peak during transition, which is characteristic of spectra obtained with hot wires. The BLTD is described along with operational requirements and limitations.

A nonperturbing boundary-layer transition detector

NASA Astrophysics Data System (ADS)

Ohare, J. E.

1985-11-01

A laser interferometer technique is being applied to the characterization of boundary-layer conditions on models in supersonic and hypersonic wind tunnels. The boundary-layer transition detector (BLTD), based on lateral interferometry, is applicable for determining the turbulence frequency spectrum of boundary layers in compressible flow. The turbulence, in terms of air density fluctuations, is detected by monitoring interferometric fringe phase shifts (in real time) formed by one beam which passes through the boundary layer and a reference beam which is outside the boundary layer. This technique is nonintrusive to the flow field unlike other commonly used methods such as pitot tube probing and hot-wire anemometry. Data which depict boundary-layer transition from laminar to turbulent flow are presented to provide comparisons of the BLTD with other measurement methods. Spectra from the BLTD reveals the presence of a high-frequency peak during transition which is characteristic of spectra obtained with hot wires. The BLTD is described along with operational requirements and limitations.

A Nonperturbing Boundary-Layer Transition Detector

NASA Astrophysics Data System (ADS)

O'Hare, J. E.

1986-01-01

A laser interferometer technique is being applied to the characterization of boundary-layer conditions on models in supersonic and hypersonic wind tunnels in the von Kaman Facility at Arnold Engineering Development Center (AEDC). The Boundary-Layer Transition Detector (BLTD), based on lateral interferometry, is applicable for determining the turbulence frequency spectrum of boundary layers in compressible flow. The turbulence, in terms of air density fluctuations, is detected by monitoring interferometric fringe phase shifts (in real time) formed by one beam which passes through the boundary layer and a reference beam which is outside the boundary layer. This technique is nonintrusive to the flow field unlike other commonly used methods such as pitot tube probing and hot-wire anemometry. Model boundary-layer data are presented at Mach 8 and compared with data recorded using other methods during boundary-layer transition from laminar to turbulent flow. Spectra from the BLTD reveal the presence of a high-frequency peak during transition, which is characteristic of spectra obtained with hot wires. The BLTD is described along with operational requirements and limitations.

Infrared spectral marker bands characterizing a transient water wire inside a hydrophobic membrane protein.

PubMed

Wolf, Steffen; Freier, Erik; Cui, Qiang; Gerwert, Klaus

2014-12-14

Proton conduction along protein-bound "water wires" is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations. A non-hydrogen bonded ("dangling") O-H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.

78 FR 46298 - Airworthiness Directives; Fokker Services B.V. Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-31

... above, this [EASA] AD requires the installation of fuses in the Max Level sensor wiring and subsequently..., which revealed that under certain failure conditions of the maximum level (Max Level) sensor wiring, a short circuit may develop that causes a hot spot on the wiring conduit, or puncturing of the wiring...

Thermal conductivity measurement of fluids using the 3ω method

NASA Astrophysics Data System (ADS)

Lee, Seung-Min

2009-02-01

We have developed a procedure to measure the thermal conductivity of dielectric liquids and gases using a steady state ac hot wire method in which a thin metal wire is used as a heater and thermometer. The temperature response of the heater wire was measured in a four-probe geometry using an electronic circuit developed for the conventional 3ω method. The measurements have been performed in the frequency range from 1 mHz to 1 kHz. We devised a method to transform the raw data into well-known linear logarithmic frequency dependence plot. After the transformation, an optimal frequency region of the thermal conductivity data was clearly determined as has been done with the data from thin metal film heater. The method was tested with air, water, ethanol, mono-, and tetraethylene glycol. Volumetric heat capacity of the fluids was also calculated with uncertainty and the capability as a probe for metal-liquid thermal boundary conductance was discussed.

Hot wire in low Reynolds number flow

NASA Technical Reports Server (NTRS)

Kolb, M. A.; Covert, E. E.

1984-01-01

Progress reports were issued on the following experiments: (1) low Reynolds number flow phenomenon of periodic vortex shedding in the wake behind a cylinder as studied by applying the hot wire anemometer technique of flow measurement. The downstream diffusion of these shed vortices was of prime concern. An evaluation of the performance of the hot wire at low Reynolds number is also considered. (2) A brief examination of the back sections of the Wright Brothers wind tunnel circuits were conducted to establish whether or not gross flow deviations were present at corners, or turning vane regions. A calibration of the test sections was done. (3) The attractiveness of using rembedded grids for airfoil calculations modeled by the Euler equations was explored. These calculations were extended to C-type grids and then to Navier-Stokes calculations,

Measurement of heat transfer coefficient using termoanemometry methods

NASA Astrophysics Data System (ADS)

Dančová, P.; Sitek, P.; Vít, T.

2014-03-01

This work deals with a measurement of heat transfer from a heated flat plate on which a synthetic jet impacts perpendicularly. Measurement of a heat transfer coefficient (HTC) is carried out using the hot wire anemometry method with glue film probe Dantec 55M47. The paper brings also results of velocity profiles measurements and turbulence intensity calculations.

Wiring design for the control of electromagnetic interference (EMI)

NASA Technical Reports Server (NTRS)

Kopasakis, George

1995-01-01

Wiring design is only one important aspect of EMI control. Other important areas for EMI are: circuit design, filtering, grounding, bonding, shielding, lighting, electrostatic discharge (ESD), transient suppression, and electromagnetic pulse (EMP). Topics covered include: wire magnetic field emissions at low frequencies; wire radiated magnetic field emissions at frequencies; wire design guidelines for EMI control; wire design guidelines for EMI control; high frequency emissions from cables; and pulse frequency spectra.

The performance of cable braids and terminations to lightning induced transients

NASA Technical Reports Server (NTRS)

Crofts, David

1991-01-01

The latest specification detailing the test waveforms for indirect lightning transients as applied to aircraft wiring systems specify very high voltages and currents. Although considerable data exists for measuring cable screen leakage using such methods as surface transfer impedance and bulk cable injection, there is little data on the likely core transient level that is likely to be induced from these threats. In particular, the new Waveform 5 at very high current levels (10 kA) is reputed to cause severe cable damage. A range of representative cables were made with various screen termination techniques and screening levels. These were tested first to determine their relative screening performance and then they were subjected to lightning transient testing to all the specified waveforms. Core voltages were measured for each test. Tests were also performed on bundles with fewer wires to determine the failure criteria with Waveform 5 and these tests also include flat conductor cables. The test showed that correctly terminated cable bundles performed well in all the tests and would provide a high level of protection to the electronic systems. The use of overbraides, provided the individual screens are well terminated, appears to be unnecessary.

Basic aerodynamic research facility for comparative studies of flow diagnostic techniques

NASA Technical Reports Server (NTRS)

Jones, Gregory S.; Gartrell, Luther R.; Stainback, P. Calvin

1987-01-01

Current flow diagnostic research efforts are focusing on higher order flow field data bases, such as those generated by laser velocimetry (LV), hot-wire anemometry, and multi-hole pressure probes. Recent low-speed comparisons of results obtained with LV and hot wires have revealed strengths and weaknesses of each instrument. A seeding study will be initiated to determine particulate tracking ability.

The static response of a bowed inclined hot wire

NASA Technical Reports Server (NTRS)

Smits, A. J.

1984-01-01

The directional sensitivity of a bowed, inclined hot wire is investigated using a simple model for the convective heat transfer. The static response is analyzed for subsonic and supersonic flows. It is shown that the effects of both end conduction and wire bowing are greater in supersonic flow. Regardless of the Mach number, however, these two phenomena have distinctly different effects; end conduction appears to be responsible for reducing the nonlinearity of the response, whereas bowing increases the directional sensitivity. Comparison with the available data suggests that the analysis is useful for interpreting the experimental results.

Dynamic gas temperature measurement system, volume 1

NASA Technical Reports Server (NTRS)

Elmore, D. L.; Robinson, W. W.; Watkins, W. B.

1983-01-01

A gas temperature measurement system with compensated frequency response of 1 kHz and capability to operate in the exhaust of a gas turbine engine combustor was developed. A review of available technologies which could attain this objective was done. The most promising method was identified as a two wire thermocouple, with a compensation method based on the responses of the two different diameter thermocouples to the fluctuating gas temperature field. In a detailed design of the probe, transient conduction effects were identified as significant. A compensation scheme was derived to include the effects of gas convection and wire conduction. The two wire thermocouple concept was tested in a laboratory burner exhaust to temperatures of about 3000 F and in a gas turbine engine to combustor exhaust temperatures of about 2400 F. Uncompensated and compensated waveforms and compensation spectra are presented.

Design and implementation of a hot-wire probe for simultaneous velocity and vorticity vector measurements in boundary layers

NASA Astrophysics Data System (ADS)

Zimmerman, S.; Morrill-Winter, C.; Klewicki, J.

2017-10-01

A multi-sensor hot-wire probe for simultaneously measuring all three components of velocity and vorticity in boundary layers has been designed, fabricated and implemented in experiments up to large Reynolds numbers. The probe consists of eight hot-wires, compactly arranged in two pairs of orthogonal ×-wire arrays. The ×-wire sub-arrays are symmetrically configured such that the full velocity and vorticity vectors are resolved about a single central location. During its design phase, the capacity of this sensor to accurately measure each component of velocity and vorticity was first evaluated via a synthetic experiment in a set of well-resolved DNS fields. The synthetic experiments clarified probe geometry effects, allowed assessment of various processing schemes, and predicted the effects of finite wire length and wire separation on turbulence statistics. The probe was subsequently fabricated and employed in large Reynolds number experiments in the Flow Physics Facility wind tunnel at the University of New Hampshire. Comparisons of statistics from the actual probe with those from the simulated sensor exhibit very good agreement in trend, but with some differences in magnitude. These comparisons also reveal that the use of gradient information in processing the probe data can significantly improve the accuracy of the spanwise velocity measurement near the wall. To the authors' knowledge, the present are the largest Reynolds number laboratory-based measurements of all three vorticity components in boundary layers.

Transport current density at temperatures up to 25 K of Cu/Ag composite sheathed 122-type tapes and wires

NASA Astrophysics Data System (ADS)

Liu, Shifa; Lin, Kaili; Yao, Chao; Zhang, Xianping; Dong, Chiheng; Wang, Dongliang; Awaji, Satoshi; Kumakura, Hiroaki; Ma, Yanwei

2017-11-01

The fabrication of iron-based superconductors with high transport critical current density (J c) and low cost is a crucial determinant of whether they can be used for practical applications. In this paper, Cu/Ag composite sheathed Sr0.6K0.4Fe2As2 (Sr122) tapes and Ba0.6K0.4Fe2As2 (Ba122) round wires were fabricated via an ex situ powder-in-tube method and heat-treated by the hot pressing and hot isostatic pressing process respectively. In order to thoroughly reveal the application potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconductors, transport J c of tapes and wires in high fields at temperatures up to 25 K was measured. High transport J c of 4.4 × 104 A cm-2 at 4.2 K and 3.6 × 103 A cm-2 at 20 K in 10 T was achieved in Cu/Ag composite sheathed Sr122 tapes. Transport J c of Ba122 wires is 9.4 × 103 A cm-2 at 4.2 K and 1.9 × 103 A cm-2 at 20 K in 10 T. These results demonstrate the great potential of Cu/Ag composite sheathed ‘122’ iron pnictide superconducting tapes and wires for high-field applications at intermediate temperatures around 20 K, which can be easily obtained by using cryocoolers.

New tools for “hot-wiring” clathrin-mediated endocytosis with temporal and spatial precision

PubMed Central

2017-01-01

Clathrin-mediated endocytosis (CME) is the major route of receptor internalization at the plasma membrane. Analysis of constitutive CME is difficult because the initiation of endocytic events is unpredictable. When and where a clathrin-coated pit will form and what cargo it will contain are difficult to foresee. Here we describe a series of genetically encoded reporters that allow the initiation of CME on demand. A clathrin-binding protein fragment (“hook”) is inducibly attached to an “anchor” protein at the plasma membrane, which triggers the formation of new clathrin-coated vesicles. Our design incorporates temporal and spatial control by the use of chemical and optogenetic methods for inducing hook–anchor attachment. Moreover, the cargo is defined. Because several steps in vesicle creation are bypassed, we term it “hot-wiring.” We use hot-wired endocytosis to describe the functional interactions between clathrin and AP2. Two distinct sites on the β2 subunit, one on the hinge and the other on the appendage, are necessary and sufficient for functional clathrin engagement. PMID:28954824

Turbulence measurements in a complex plowfield using a crossed hot-wire. M.S. Thesis

NASA Technical Reports Server (NTRS)

Mckillop, B. E.

1983-01-01

Turbulence was quantified in complex axisymmetric, nonreacting, nonswirling flowfields using a crossed hot-wire anemometer. Mean velocity, turbulence intensities, turbulent viscosity, and Reynolds tree were measured in round free jet and confined jet flowfields. The confined jet, a model of an axisymmetric can combustor, had an expansion ratio D/d=2, an expansion angle of 90 deg, and an axial location increments of 0.5 diameters. The confined jet was studied with and without a contraction nozzle. Free jet measurements validated the experimental technique and data reduction. Results show good agreement with those of previous research. Measurements in the confined jet indicate that the cross hot-wire used cannot handle axial flow reversal and the experimental technique is inadequate for measuring time-mean radial velocity. Other quantities show a high level of comparability.

METHOD FOR MAKING FUEL ELEMENTS

DOEpatents

Kates, L.W.; Campbell, R.W.; Heartel, R.H.W.

1960-08-01

A method is given for making zirconium-clad uranium wire. A tube of zirconium is closed with a zirconium plug, after which a chilled uranium core is inserted in the tube to rest against the plug. Additional plugs and cores are inserted alternately as desired. The assembly is then sheathed with iron, hot worked to the desired size, and the iron sheath removed.

On the possibility to grow zinc oxide-based transparent conducting oxide films by hot-wire chemical vapor deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrutis, Adulfas, E-mail: adulfas.abrutis@chf.vu.lt; Silimavicus, Laimis; Kubilius, Virgaudas

Hot-wire chemical vapor deposition (HW-CVD) was applied to grow zinc oxide (ZnO)-based transparent conducting oxide (TCO) films. Indium (In)-doped ZnO films were deposited using a cold wall pulsed liquid injection CVD system with three nichrome wires installed at a distance of 2 cm from the substrate holder. The wires were heated by an AC current in the range of 0–10 A. Zn and In 2,2,6,6-tetramethyl-3,5-heptanedionates dissolved in 1,2-dimethoxyethane were used as precursors. The hot wires had a marked effect on the growth rates of ZnO, In-doped ZnO, and In{sub 2}O{sub 3} films; at a current of 6–10 A, growth rates weremore » increased by a factor of ≈10–20 compared with those of traditional CVD at the same substrate temperature (400 °C). In-doped ZnO films with thickness of ≈150 nm deposited on sapphire-R grown at a wire current of 9 A exhibited a resistivity of ≈2 × 10{sup −3} Ωcm and transparency of >90% in the visible spectral range. These initial results reveal the potential of HW-CVD for the growth of TCOs.« less

Note: Improving long-term stability of hot-wire anemometer sensors by means of annealing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lundström, H., E-mail: hans.lundstrom@hig.se

2015-08-15

Annealing procedures for hot-wire sensors of platinum and platinum-plated tungsten have been investigated experimentally. It was discovered that the two investigated sensor metals behave quite differently during the annealing process, but for both types annealing may improve long-term stability considerably. Measured drift of sensors both without and with prior annealing is presented. Suggestions for suitable annealing temperatures and times are given.

Measurement and Modeling of Dispersive Pulse Propagation in Drawn Wire Waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

Measurement and modeling of dispersive pulse propagation in draw wire waveguides

NASA Technical Reports Server (NTRS)

Madaras, Eric I.; Kohl, Thomas W.; Rogers, Wayne P.

1995-01-01

An analytical model of dispersive pulse propagation in semi-infinite cylinders due to transient axially symmetric end conditions has been experimentally investigated. Specifically, the dispersive propagation of the first axially symmetric longitudinal mode in thin wire waveguides, which have ends in butt contact with longitudinal piezoelectric ultrasonic transducers, is examined. The method allows for prediction of a propagated waveform given a measured source waveform, together with the material properties of the cylinder. Alternatively, the source waveform can be extracted from measurement of the propagated waveform. The material properties required for implementation of the pulse propagation model are determined using guided wave phase velocity measurements. Hard tempered aluminum 1100 and 304 stainless steel wires, with 127, 305, and 406 micron diam., were examined. In general, the drawn wires were found to behave as transversely isotropic media.

A calibration loop to test hot-wire response under supercritical conditions

NASA Astrophysics Data System (ADS)

Radulović, Ivana; Vukoslavčević, P. V.; Wallace, J. M.

2004-11-01

A calibration facility to test the response of hot-wires in CO2 flow under supercritical conditions has been designed and constructed. It is capable of inducing variable speeds at different temperatures and pressures in the ranges of 0.15 - 2 m/s, 15 - 70 deg. C and 1 - 100 bar. The facility is designed as a closed loop with a test section, pump, electrical heater, DC motor and different regulating and measuring devices. The test section is a small tunnel, with a diffuser, honeycomb, screens and a nozzle to provide a uniform flow with a low turbulence level. The speed variation is created by a sealed, magnetic driven gear pump, with a variable rpm DC motor. Using the electrical heater and regulating the amount of CO2 in the facility, the desired temperature and pressure can be reached. The dimensions of the instalation are minimized to reduce the heat, pump power required, and CO2 consumption and to optimize safety. Preliminary testing of a single hot-wire velocity sensor at constant pressure (80 bar) and variable speed and temperature will be briefly described. The hot-wire probes calibrated in this loop will be used to measure turbulence properties in supercritical CO2 in support of improved designs of nuclear reactors to be cooled by supercritical fluids.

Orbiter CCTV video signal noise analysis

NASA Technical Reports Server (NTRS)

Lawton, R. M.; Blanke, L. R.; Pannett, R. F.

1977-01-01

The amount of steady state and transient noise which will couple to orbiter CCTV video signal wiring is predicted. The primary emphasis is on the interim system, however, some predictions are made concerning the operational system wiring in the cabin area. Noise sources considered are RF fields from on board transmitters, precipitation static, induced lightning currents, and induced noise from adjacent wiring. The most significant source is noise coupled to video circuits from associated circuits in common connectors. Video signal crosstalk is the primary cause of steady state interference, and mechanically switched control functions cause the largest induced transients.

State of the metal core in nanosecond exploding wires and related phenomena

NASA Astrophysics Data System (ADS)

Sarkisov, G. S.; Sasorov, P. V.; Struve, K. W.; McDaniel, D. H.

2004-08-01

Experiments show that an expanding metal wire core that results from a nanosecond electrical explosion in vacuum consists primarily of three different states: solid, microdrop, and gas-plasma. The state of the wire core depends both on the amount of energy deposited before the voltage breakdown and on the heating conditions. For small amounts of deposited energy (on the order of solid-stage enthalpy), the wire core remains in a solid state or is partially disintegrated. For a high level of deposited energy (more than vaporization energy) the wire core is in a gas-plasma state. For an intermediate level of deposited energy (more than melting but less than vaporization), the wire disintegrates into hot liquid microdrops or clusters of submicron size. For a wire core in the cluster state, interferometry demonstrates weak (or even absent) phaseshift. Light emission shows a "firework effect"—the long late-time radiation related to the emission by the expanding cylinder of hot microparticles. For the wire core in a gas-plasma state, interferometry demonstrates a large phaseshift and a fast reduction in light emission due to adiabatic cooling of the expanding wire core. The simulation of this firework effect agrees well with experimental data, assuming submicron size and a temperature approaching boiling for the expanded microparticles cylinder.

Ice Particle Impact on Cloud Water Content Instrumentation

NASA Technical Reports Server (NTRS)

Emery, Edward F.; Miller, Dean R.; Plaskon, Stephen R.; Strapp, Walter; Lillie, Lyle

2004-01-01

Determining the total amount of water contained in an icing cloud necessitates the measurement of both the liquid droplets and ice particles. One commonly accepted method for measuring cloud water content utilizes a hot wire sensing element, which is maintained at a constant temperature. In this approach, the cloud water content is equated with the power required to keep the sense element at a constant temperature. This method inherently assumes that impinging cloud particles remain on the sensing element surface long enough to be evaporated. In the case of ice particles, this assumption requires that the particles do not bounce off the surface after impact. Recent tests aimed at characterizing ice particle impact on a thermally heated wing section, have raised questions about the validity of this assumption. Ice particles were observed to bounce off the heated wing section a very high percentage of the time. This result could have implications for Total Water Content sensors which are designed to capture ice particles, and thus do not account for bouncing or breakup of ice particles. Based on these results, a test was conducted to investigate ice particle impact on the sensing elements of the following hot-wire cloud water content probes: (1) Nevzorov Total Water Content (TWC)/Liquid Water Content (LWC) probe, (2) Science Engineering Associates TWC probe, and (3) Particle Measuring Systems King probe. Close-up video imaging was used to study ice particle impact on the sensing element of each probe. The measured water content from each probe was also determined for each cloud condition. This paper will present results from this investigation and attempt to evaluate the significance of ice particle impact on hot-wire cloud water content measurements.

A real time dynamic data acquisition and processing system for velocity, density, and total temperature fluctuation measurements

NASA Technical Reports Server (NTRS)

Clukey, Steven J.

1991-01-01

The real time Dynamic Data Acquisition and Processing System (DDAPS) is described which provides the capability for the simultaneous measurement of velocity, density, and total temperature fluctuations. The system of hardware and software is described in context of the wind tunnel environment. The DDAPS replaces both a recording mechanism and a separate data processing system. DDAPS receives input from hot wire anemometers. Amplifiers and filters condition the signals with computer controlled modules. The analog signals are simultaneously digitized and digitally recorded on disk. Automatic acquisition collects necessary calibration and environment data. Hot wire sensitivities are generated and applied to the hot wire data to compute fluctuations. The presentation of the raw and processed data is accomplished on demand. The interface to DDAPS is described along with the internal mechanisms of DDAPS. A summary of operations relevant to the use of the DDAPS is also provided.

Evaluation of emissions from simulated commercial meat wrapping operations using PVC wrap.

PubMed

Smith, T J; Cafarella, J J; Chelton, C; Crowley, S

1983-03-01

Meatwrapper's asthma is an elusive health problem with a suspected relationship to exposure to emissions from polyvinyl chloride (PVC) film cut with a hot wire. A study was conducted to determine how the type of wrap cutter (wire or rod) and its temperature affected the emissions from a simulated occupational wrapping process. The cutting temperatures covered the same range as was measured in Boston retail food stores. A commercial wrapping machine and samples of commercial PVC meat and produce wraps were used. Seventy five percent of the particulate from the hot wire was respirable, and the quantity of emissions was a strong function of the film tension and cutting technique. Particulate emissions did not increase steadily with increasing wire temperature, but plateaued or declined at high temperatures. Particulate emissions from the rod cutter were very low at low temperatures, but exceeded those of the wire at temperatures above 200 degrees C. The particulate was 100% dioctyl adipate (DOA, the plasticizer in the wrap) with wire temperatures below 200 degrees C, and was approximately 80% DOA for temperatures above this. Gaseous HCl was not detected in emissions from a hot wire operated below 150 degrees C, but HCl emissions increased rapidly to a plateau for temperatures above 200 degrees C. Approximately 20% of the HCl produced at temperatures above 200 degrees C was associated with the particulate, which appeared to act as a carrier and transport the HCl through water filled impingers. Field tests are needed to determine if particulate produced in the workplace may also behave as a carrier for HCl.

Development of instrumentation for measurements of two components of velocity with a single sensing element

NASA Astrophysics Data System (ADS)

Byers, C. P.; Fu, M. K.; Fan, Y.; Hultmark, M.

2018-02-01

A novel method of obtaining two orthogonal velocity components with high spatial and temporal resolution is investigated. Both components are obtained utilizing a single sensing nanoribbon by combining the two independent operating modes of classic hot wire anemometry and the newly discovered elastic filament velocimetry (EFV). In contrast to hot wire anemometry, EFV measures fluid velocity through correlating the fluid forcing with the internal strain of the wire. In order to utilize both modes of operation, a system that switches between the two operating modes is built and characterized, and the theoretically predicted sensing response time in water is compared to experimental results. The sensing system is capable of switching between the two modes of operation at a frequency of 100 kHz with minimal attenuation with an uncompensated repetition rate up to 3 kHz or up to 10 kHz utilizing modest signal compensation. While further characterization of the sensor performance in air is needed, this methodology enables a technique for obtaining well-resolved yet cost-efficient directional measurements of flow velocities which, for example, can be used for distributed measurements of velocity or measurements of turbulent stresses with excellent spatial resolution.

Experimental and numerical analysis of interfilament resistances in NbTi strands

NASA Astrophysics Data System (ADS)

Breschi, M.; Massimini, M.; Ribani, P. L.; Spina, T.; Corato, V.

2014-05-01

Superconducting strands are composite wires made of fine superconducting filaments embedded in a metallic matrix. The transverse resistivity among superconducting filaments affects the coupling losses during electromagnetic transients and the electro-thermal behavior of the wire in case of a quench. A direct measurement of the transverse interfilament resistance as a function of temperature in NbTi multi-filamentary wires was performed at the ENEA Frascati Superconductivity Division, Italy by means of a four-probe method. The complexity of these measurements is remarkable, due to the current distribution phenomena that occur among superconducting filaments during these tests. A two-dimensional finite element method model of the wire cross section and a three-dimensional electrical circuit model of the wire sample developed at the University of Bologna are applied here to derive qualitative and quantitative information about the transverse electrical resistance matrix. The experiment is aimed at verifying the qualitative behaviors and trends predicted by the numerical calculations, especially concerning the current redistribution length and consequent length effects of the sample under test. A fine tuning of the model parameters at the filament level allowed us to reproduce the experimental results and get quantitative information about the current distribution phenomena between filaments.

Jet Mixing Enhancement by Feedback Control

NASA Technical Reports Server (NTRS)

Glauser, Mark; Taylor, Jeffrey

1999-01-01

The objective of this work has been to produce methodologies for high speed jet noise reduction based on natural mechanisms and enhanced feedback control to affect frequencies and structures in a prescribed manner. In this effort the two-point hot wire measurements obtained in the Langley jet facility by Ukeiley were used in conjuction with linear stochastic estimation (LSE) to implement the LSE component of the complementary technique. This method combines the Proper Orthogonal Decomposition (POD) and LSE to provide an experimental low dimensional time dependent description of the flow field. From such a description it should be possible to identify short time high strain rate events in the jet which contribute to the noise. The main task completed for this effort is summarized: LSE experiments were performed at the downstream locations where the two point hot wire measurements have been obtained by Ukeiley. These experiments involved sampling simultaneously hot wire signals from a relatively course spatial grid in gamma and theta. From this simultaneous data, coupled with the two-point measurements of Ukeiley via the LSE components of the complementary technique, an experimental low dimensional description of the jet at 4, 5, 6, 7 and 8 diameters downstream was obtained for Mach numbers of 0.3 and 0.6. We first present an overview of the theory involved. We finish up with a statement of the work performed and finally provide charts from a 1999 APS talk which summarizes the results.

Generation and Transport of Hot Electrons in Cone-Wire Targets

NASA Astrophysics Data System (ADS)

Beg, Farhat

2009-11-01

We present results from a series of experiments where cone-wire targets in various configurations were employed both to assess hot electron coupling efficiency, and to reveal the source temperature of the hot electrons. Initial experiments were performed on the Vulcan petawatt laser at the Rutherford Appleton Laboratory and Titan laser at the Lawrence Livermore National Laboratory. Results with aluminum cones joined to Cu wires of diameters from 10 to 40 μm show that the laser coupling efficiency to electron energy within the wire is proportional to the cross sectional area of the wire. In addition, coupling into the wire was observed to decrease with the laser prepulse and cone-wall thickness. More recently, this study was extended, using the OMEGA EP laser. The resulting changes in coupling energy give indications of the scaling as we approach FI-relevant conditions. Requirements for FI scale fast ignition cone parameters: tip thickness, wall thickness, laser prepulse and laser pulse length, will be discussed. In collaboration with T. Yabuuchi, T. Ma, D. Higginson, H. Sawada, J. King, M.H. Key, K.U. Akli, Al Elsholz, D. Batani, H. Chen, R.R. Freeman, L. Gizzi, J. Green, S. Hatchett, D. Hey, P. Jaanimagi, J. Koch, K. L. Lancaster, D.Larson, A.J. MacKinnon, H. McLean, A. MacPhee, P.A. Norreys, P.K Patel, R. B. Stephens, W. Theobald, R. Town, M. Wei, S. Wilks, Roger Van Maren, B. Westover and L. VanWoerkom.

Development of an integrated BEM approach for hot fluid structure interaction

NASA Technical Reports Server (NTRS)

Dargush, G. F.; Banerjee, P. K.; Shi, Y.

1990-01-01

A comprehensive boundary element method is presented for transient thermoelastic analysis of hot section Earth-to-Orbit engine components. This time-domain formulation requires discretization of only the surface of the component, and thus provides an attractive alternative to finite element analysis for this class of problems. In addition, steep thermal gradients, which often occur near the surface, can be captured more readily since with a boundary element approach there are no shape functions to constrain the solution in the direction normal to the surface. For example, the circular disc analysis indicates the high level of accuracy that can be obtained. In fact, on the basis of reduced modeling effort and improved accuracy, it appears that the present boundary element method should be the preferred approach for general problems of transient thermoelasticity.

Velocity Measurement Systems for a Low-speed Wind Tunnel

DTIC Science & Technology

2015-04-29

Office P.O. Box 12211 Research Triangle Park, NC 27709-2211 wind tunnel PIV hot wire particle image velocimetry REPORT DOCUMENTATION PAGE 11. SPONSOR...Velocity Measurement Systems for a Low-speed Wind Tunnel Report Title Funds were provided by the ARO for the purchase of TSI hot- wire anemometer equipment...implemented. In the summer of 2011, the focus of the summer camp was on wind turbines , and for the last two summers, the STEM outreach camp has studied

The Study the Vibration Condition of the Blade of the Gas Turbine Engine with an All-metal Wire Rope Damper in the Area Mount of the Blade to the Disk

NASA Astrophysics Data System (ADS)

Melentjev, Vladimir S.; Gvozdev, Alexander S.

2018-01-01

Improving the reliability of modern turbine engines is actual task. This is achieved due to prevent a vibration damage of the operating blades. On the department of structure and design of aircraft engines have accumulated a lot of experimental data on the protection of the blades of the gas turbine engine from a vibration. In this paper we proposed a method for calculating the characteristics of wire rope dampers in the root attachment of blade of a gas turbine engine. The method is based on the use of the finite element method and transient analysis. Contact interaction (Lagrange-Euler method) between the compressor blade and the disc of the rotor has been taken into account. Contribution of contact interaction between details in damping of the system was measured. The proposed method provides a convenient way for the iterative selection of the required parameters the wire rope elastic-damping element. This element is able to provide the necessary protection from the vibration for the blade of a gas turbine engine.

Energy dissipation of composite multifilamentary superconductors for high-current ramp-field magnet applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gung, C.Y.

1993-01-01

Energy dissipation, which is also called AC loss, of a composite multifilamentary superconducting wire is one of the most fundamental concerns in building a stable superconducting magnet. Characterization and reduction of AC losses are especially important in designing a superconducting magnet for generating transient magnetic fields. The goal of this thesis is to improve the understanding of AC-loss properties of superconducting wires developed for high-current ramp-field magnet applications. The major tasks include: (1) building an advanced AC-loss measurement system, (2) measuring AC losses of superconducting wires under simulated pulse magnet operations, (3) developing an analytical model for explaining the newmore » AC-loss properties found in the experiment, and (4) developing a computational methodology for comparing AC losses of a superconducting wire with those of a cable for a superconducting pulse magnet. A new experimental system using an isothermal calorimetric method was designed and constructed to measure the absolute AC losses in a composite superconductor. This unique experimental setup is capable of measuring AC losses of a brittle Nb{sub 3}Sn wire carrying high AC current in-phase with a large-amplitude pulse magnetic field. Improvements of the accuracy and the efficiency of this method are discussed. Three different types of composite wire have been measured: a Nb{sub 3}Sn modified jelly-roll (MJR) internal-tin wire used in a prototype ohmic heating coil, a Nb{sub 3}Sn internal-tin wire developed for a fusion reactor ohmic heating coil, and a NbTi wire developed for the magnets in a particle accelerator. The cross sectional constructions of these wires represent typical commercial wires manufactured for pulse magnet applications.« less

Development of an integrated BEM approach for hot fluid structure interaction

NASA Technical Reports Server (NTRS)

Dargush, Gary F.; Banerjee, Prasanta K.; Dunn, Michael G.

1988-01-01

Significant progress was made toward the goal of developing a general purpose boundary element method for hot fluid-structure interaction. For the solid phase, a boundary-only formulation was developed and implemented for uncoupled transient thermoelasticity in two dimensions. The elimination of volume discretization not only drastically reduces required modeling effort, but also permits unconstrained variation of the through-the-thickness temperature distribution. Meanwhile, for the fluids, fundamental solutions were derived for transient incompressible and compressible flow in the absence of the convective terms. Boundary element formulations were developed and described. For the incompressible case, the necessary kernal functions, under transient and steady-state conditions, were derived and fully implemented into a general purpose, multi-region boundary element code. Several examples were examined to study the suitability and convergence characteristics of the various algorithms.

Hot filament-dissociation of (CH3)3SiH and (CH3)4Si, probed by vacuum ultra violet laser time of flight mass spectroscopy.

PubMed

Sharma, Ramesh C; Koshi, Mitsuo

2006-11-01

The decomposition of trimethylsilane and tetramethylsilane has been investigated for the first time, using hot wire (catalytic) at various temperatures. Trimethylsilane is catalytic-dissociated in these species SiH(2), CH(3)SiH, CH(3), CH(2)Si. Time of flight mass spectroscopy signal of these species are linearly increasing with increasing catalytic-temperature. Time of flight mass spectroscopy (TOFMS) signals of (CH(3))(3)SiH and photodissociated into (CH(3))(2)SiH are decreasing with increasing hot filament temperature. TOFMS signal of (CH(3))(4)Si is decreasing with increasing hot wire temperature, but (CH(3))(3)Si signal is almost constant with increasing the temperature. We calculated activation energies of dissociated species of the parental molecules for fundamental information of reaction kinetics for the first time. Catalytic-dissociation of trimethylsilane, and tetramethylsilane single source time of flight coupled single photon VUV (118 nm) photoionization collisionless radicals at temperature range of tungsten filament 800-2360 K. The study is focused to understand the fundamental information on reaction kinetics of these molecules at hot wire temperature, and processes of catalytic-chemical vapour deposition (Cat-CVD) technique which could be implemented in amorphous and crystalline SiC semiconductors thin films.

Lightning induced currents in aircraft wiring using low level injection techniques

NASA Technical Reports Server (NTRS)

Stevens, E. G.; Jordan, D. T.

1991-01-01

Various techniques were studied to predict the transient current induced into aircraft wiring bundles as a result of an aircraft lightning strike. A series of aircraft measurements were carried out together with a theoretical analysis using computer modeling. These tests were applied to various aircraft and also to specially constructed cylinders installed within coaxial return conductor systems. Low level swept frequency CW (carrier waves), low level transient and high level transient injection tests were applied to the aircraft and cylinders. Measurements were made to determine the transfer function between the aircraft drive current and the resulting skin currents and currents induced on the internal wiring. The full threat lightning induced transient currents were extrapolated from the low level data using Fourier transform techniques. The aircraft and cylinders used were constructed from both metallic and CFC (carbon fiber composite) materials. The results show the pulse stretching phenomenon which occurs for CFC materials due to the diffusion of the lightning current through carbon fiber materials. Transmission Line Matrix modeling techniques were used to compare theoretical and measured currents.

Time to transient and stable reductions in hot flush frequency in postmenopausal women using conjugated estrogens/bazedoxifene.

PubMed

Pinkerton, JoAnn V; Bushmakin, Andrew G; Abraham, Lucy; Komm, Barry S; Bobula, Joel

2017-09-01

This post hoc analysis estimates time to transient and stable reductions in hot flush frequency in postmenopausal women using conjugated estrogens/bazedoxifene. In the 12-week Selective estrogens, Menopause, And Response to Therapy (SMART)-2 trial of conjugated estrogens/bazedoxifene 0.45 mg/20 mg and 0.625 mg/20 mg, women with at least seven moderate/severe hot flushes per day or 50 per week at screening recorded frequency of moderate/severe hot flushes in diaries. Nonparametric models and SAS Proc Lifetest were used to estimate median times to various degrees of transient reductions (first day with improvement) and stable reductions (first day with improvement maintained through study's end) in hot flush frequency. Treatment produced transient hot flush reductions of 40% to 100% and stable reductions of 30% to 100% significantly faster than placebo. Median time to a transient 50% reduction was 8 days for conjugated estrogens/bazedoxifene 0.45 mg/20 mg, 9.5 for 0.625 mg/20 mg, and 10 for placebo; median time to a stable 50% reduction was 9, 10, and 38 days. Median time to a transient 90% reduction was 32 and 22.5 days for 0.45 mg/20 mg and 0.625 mg/20 mg, and median time to a stable 90% reduction was 83 and 29 days, respectively; median times to transient/stable 90% reductions were not reached during the 12-week study in the placebo group. Although not all women using conjugated estrogens/bazedoxifene achieve permanent elimination of hot flushes, the frequency is likely to be substantially reduced during the first week to month. Women can expect approximately 50% reduction in hot flush frequency after about 8 to 10 days, and sustained improvement with continued treatment.

Crossed hot-wire data acquisition and reduction system

NASA Technical Reports Server (NTRS)

Westphal, R. V.; Mehta, R. D.

1984-01-01

The report describes a system for rapid computerized calibration acquisition, and processing of data from a crossed hot-wire anemometer is described. Advantages of the system are its speed, minimal use of analog electronics, and improved accuracy of the resulting data. Two components of mean velocity and turbulence statistics up to third order are provided by the data reduction. Details of the hardware, calibration procedures, response equations, software, and sample results from measurements in a turbulent plane mixing layer are presented.

Understanding and Prevention of Transient Voltages and Dielectric Breakdown in High Voltage Battery Systems

DTIC Science & Technology

2017-07-31

as it is one faced every day as power systems engineers try to integrate batteries, solar panels, and wind turbines onto the already existing...Amendment-OOO l.ashx. [Accessed 10 Dec 2013] (7) "Copper Wire Resistance and Inductance Calculator", Ampbooks.com, 20 I 7. [Online]. Available: https...ampbooks.com/home/amplifier-calcu lators/ wire -inductance/. [Accessed: 21- May- 2017). (8) "What is Transient Voltage? - E lectronic Products

Measurement of the Arithmetic Mean Velocity of a Pulsating Flow of High Velocity by the Hot-Wire Method

DTIC Science & Technology

1946-04-01

electric Ympulse’fs iransaitteh and ati$ lified by the-amplifier stages. A variationyof the potential between * grid’and,:cathod.e of the. chrrent...ethods:in Engineering. McGraw-hill Book Co. Inc., 1940, p. 327, "&.: ,. , . 7: -. .’,.:+.- .(: .- ..I‘ 5. Shea, ’Transmission Networks and rave Filters

Experimental thermal conductivity, thermal diffusivity, and specific heat values for mixtures of nitrogen, oxygen, and argon

NASA Technical Reports Server (NTRS)

Perkins, R. A.; Cieszkiewicz, M. T.

1991-01-01

Experimental measurements of thermal conductivity and thermal diffusivity obtained with a transient hot-wire apparatus are reported for three mixtures of nitrogen, oxygen, and argon. Values of the specific heat, Cp, are calculated from these measured values and the density calculated with an equation of state. The measurements were made at temperatures between 65 and 303 K with pressures between 0.1 and 70 MPa. The data cover the vapor, liquid, and supercritical gas phases for the three mixtures. The total reported points are 1066 for the air mixture (78.11 percent nitrogen, 20.97 percent oxygen, and 0.92 percent argon), 1058 for the 50 percent nitrogen, 50 percent oxygen mixture, and 864 for the 25 percent nitrogen, 75 oxygen mixture. Empirical thermal conductivity correlations are provided for the three mixtures.

Development of subminiature multi-sensor hot-wire probes

NASA Technical Reports Server (NTRS)

Westphal, Russell V.; Ligrani, Phillip M.; Lemos, Fred R.

1988-01-01

Limitations on the spatial resolution of multisensor hot wire probes have precluded accurate measurements of Reynolds stresses very near solid surfaces in wind tunnels and in many practical aerodynamic flows. The fabrication, calibration and qualification testing of very small single horizontal and X-array hot-wire probes which are intended to be used near solid boundaries in turbulent flows where length scales are particularly small, is described. Details of the sensor fabrication procedure are reported, along with information needed to successfully operate the probes. As compared with conventional probes, manufacture of the subminiature probes is more complex, requiring special equipment and careful handling. The subminiature probes tested were more fragile and shorter lived than conventional probes; they obeyed the same calibration laws but with slightly larger experimental uncertainty. In spite of these disadvantages, measurements of mean statistical quantities and spectra demonstrate the ability of the subminiature sensors to provide the measurements in the near wall region of turbulent boundary layers that are more accurate than conventional sized probes.

Flow visualization and flow field measurements of a 1/12 scale tilt rotor aircraft in hover

NASA Technical Reports Server (NTRS)

Coffen, Charles D.; George, Albert R.; Hardinge, Hal; Stevenson, Ryan

1991-01-01

The results are given of flow visualization studies and inflow velocity field measurements performed on a 1/12 scale model of the XV-15 tilt rotor aircraft in the hover mode. The complex recirculating flow due to the rotor-wake-body interactions characteristic of tilt rotors was studied visually using neutrally buoyant soap bubbles and quantitatively using hot wire anemometry. Still and video photography were used to record the flow patterns. Analysis of the photos and video provided information on the physical dimensions of the recirculating fountain flow and on details of the flow including the relative unsteadiness and turbulence characteristics of the flow. Recirculating flows were also observed along the length of the fuselage. Hot wire anemometry results indicate that the wing under the rotor acts to obstruct the inflow causing a deficit in the inflow velocities over the inboard region of the model. Hot wire anemometry also shows that the turbulence intensities in the inflow are much higher in the recirculating fountain reingestion zone.

Current distribution in conducting nanowire networks

NASA Astrophysics Data System (ADS)

Kumar, Ankush; Vidhyadhiraja, N. S.; Kulkarni, Giridhar U.

2017-07-01

Conducting nanowire networks find diverse applications in solar cells, touch-screens, transparent heaters, sensors, and various related transparent conducting electrode (TCE) devices. The performances of these devices depend on effective resistance, transmittance, and local current distribution in these networks. Although, there have been rigorous studies addressing resistance and transmittance in TCE, not much attention is paid on studying the distribution of current. Present work addresses this compelling issue of understanding current distribution in TCE networks using analytical as well as Monte-Carlo approaches. We quantified the current carrying backbone region against isolated and dangling regions as a function of wire density (ranging from percolation threshold to many multiples of threshold) and compared the wired connectivity with those obtained from template-based methods. Further, the current distribution in the obtained backbone is studied using Kirchhoff's law, which reveals that a significant fraction of the backbone (which is believed to be an active current component) may not be active for end-to-end current transport due to the formation of intervening circular loops. The study shows that conducting wire based networks possess hot spots (extremely high current carrying regions) which can be potential sources of failure. The fraction of these hot spots is found to decrease with increase in wire density, while they are completely absent in template based networks. Thus, the present work discusses unexplored issues related to current distribution in conducting networks, which are necessary to choose the optimum network for best TCE applications.

Effect of rolling on the high temperature tensile and stress-rupture properties of tungsten fiber-superalloy composites

NASA Technical Reports Server (NTRS)

Petrasek, D. W.

1974-01-01

An investigation was conducted to determine the effects of mechanical working on the 1093 C (2000 F) tensile and stress-rupture strength of tungsten alloy/superalloy composites. Hot pressed composites containing either conventional tungsten lamp filament wire or tungsten-1% ThO2 wire and a nickel base alloy matrix were hot rolled at 1093 C (2000 F). The hot pressed and rolled composite specimens were then tested in tension and stress-rupture at 1093 C (2000 F). Rolling decreased the degree of fiber-matrix reaction as a function of time of exposure at 1093 C (2000 F). The stress-rupture properties of the rolled composites were superior to hot pressed composites containing equivalent diameter fibers. Rolling did not appreciably affect the 1093 C (2000 F) ultimate tensile strength of the composites.

Wind tunnel measurements of three-dimensional wakes of buildings. [for aircraft safety applications

NASA Technical Reports Server (NTRS)

Logan, E., Jr.; Lin, S. H.

1982-01-01

Measurements relevant to the effect of buildings on the low level atmospheric boundary layer are presented. A wind tunnel experiment was undertaken to determine the nature of the flow downstream from a gap between two transversely aligned, equal sized models of rectangular cross section. These building models were immersed in an equilibrium turbulent boundary layer which was developed on a smooth floor in a zero longitudinal pressure gradient. Measurements with an inclined (45 degree) hot-wire were made at key positions downstream of models arranged with a large, small, and no gap between them. Hot-wire theory is presented which enables computation of the three mean velocity components, U, V and W, as well as Reynolds stresses. These measurements permit understanding of the character of the wake downstream of laterally spaced buildings. Surface streamline patterns obtained by the oil film method were used to delineate the separation region to the rear of the buildings for a variety of spacings.

Experiments on the instabilities in swirling and non-swirling free jets

NASA Astrophysics Data System (ADS)

Panda, Jayanta

1990-08-01

Instabilities present in a free swirling jet in Reynolds number range from 20,000 to 60,000 and swirl number of 0.45 were studied using smoke visualization and hot wire measurements. A nonswirling jet of Reynolds number 60,000 produced from the same facility was also studied for validation of the experimental procedures and direct comparison with the swirling jet. Time-mean velocity components and turbulence intensity were surveyed using a single hot wire (nonswirling jet) and a V wire (swirling jet) probe. To enhance the understanding of these instabilities, axisymmetric and helical waves were excited in the Strouhal number range 0.75 to 1.5 (swirling jet) and 0.9 to 3.75 (nonswirling jet) by acoustic excitation.

Scalable Nernst thermoelectric power using a coiled galfenol wire

NASA Astrophysics Data System (ADS)

Yang, Zihao; Codecido, Emilio A.; Marquez, Jason; Zheng, Yuanhua; Heremans, Joseph P.; Myers, Roberto C.

2017-09-01

The Nernst thermopower usually is considered far too weak in most metals for waste heat recovery. However, its transverse orientation gives it an advantage over the Seebeck effect on non-flat surfaces. Here, we experimentally demonstrate the scalable generation of a Nernst voltage in an air-cooled metal wire coiled around a hot cylinder. In this geometry, a radial temperature gradient generates an azimuthal electric field in the coil. A Galfenol (Fe0.85Ga0.15) wire is wrapped around a cartridge heater, and the voltage drop across the wire is measured as a function of axial magnetic field. As expected, the Nernst voltage scales linearly with the length of the wire. Based on heat conduction and fluid dynamic equations, finite-element method is used to calculate the temperature gradient across the Galfenol wire and determine the Nernst coefficient. A giant Nernst coefficient of -2.6 μV/KT at room temperature is estimated, in agreement with measurements on bulk Galfenol. We expect that the giant Nernst effect in Galfenol arises from its magnetostriction, presumably through enhanced magnon-phonon coupling. Our results demonstrate the feasibility of a transverse thermoelectric generator capable of scalable output power from non-flat heat sources.

An Investigation of Transonic Resonance in a Mach 2.2 Round Convergent-Divergent Nozzle

NASA Technical Reports Server (NTRS)

Dippold, Vance F., III; Zaman, Khairul B. M. Q.

2015-01-01

Hot-wire and acoustic measurements were taken for a round convergent nozzle and a round convergent-divergent (C-D) nozzle at a jet Mach number of 0.61. The C-D nozzle had a design Mach number of 2.2. Compared to the convergent nozzle jet flow, the Mach 2.2 nozzle jet flow produced excess broadband noise (EBBN). It also produced a transonic resonance tone at 1200 Herz. Computational simulations were performed for both nozzle flows. A steady Reynolds-Averaged Navier-Stokes simulation was performed for the convergent nozzle jet flow. For the Mach 2.2 nozzle flow, a steady RANS simulation, an unsteady RANS (URANS) simulation, and an unsteady Detached Eddy Simulation (DES) were performed. The RANS simulation of the convergent nozzle showed good agreement with the hot-wire velocity and turbulence measurements, though the decay of the potential core was over-predicted. The RANS simulation of the Mach 2.2 nozzle showed poor agreement with the experimental data, and more closely resembled an ideally-expanded jet. The URANS simulation also showed qualitative agreement with the hot-wire data, but predicted a transonic resonance at 1145 Herz. The DES showed good agreement with the hot-wire velocity and turbulence data. The DES also produced a transonic tone at 1135 Herz. The DES solution showed that the destabilization of the shock-induced separation region inside the nozzle produced increased levels of turbulence intensity. This is likely the source of the EBBN.

Evaluation of tensile strength and surface topography of orthodontic wires after infection control procedures: An in vitro study

PubMed Central

Brindha, M.; Kumaran, N. Kurunji; Rajasigamani, K.

2014-01-01

Aim: The aim of this study is to evaluate, the influence of four types of sterilization/disinfection procedures (autoclave, hot air oven, glutaraldehyde, and ultraviolet [UV] light) on the tensile strength and surface topography of three orthodontic wires (stainless steel (SS), titanium - molybdenum alloy [TMA], and cobalt chromium (CoCr)). Materials and Methods: Sample comprised of three types of 8 inches straight length segments of orthodontic wires. They were divided into three groups according to wire composition comprising of 50 samples each. Totally 50 samples of each group were then equally divided into five subgroups according to sterilization method. After sterilization and disinfection of the experimental group, surface topography was examined with scanning electron microscope (SEM) and tensile strength was tested using universal testing machine. Result: The results of this study show that the mean ultimate tensile strength (UTS) of SS wire after four sterilization procedures were similar to the control group (1845.815 ± 142.29 MPa). The mean UTS of TMA wire increases after four sterilization procedures when compared with the control group (874.107 ± 275.939 MPa). The mean UTS of CoCr wire remains same after UV light disinfection, but increases after other three sterilization procedures when compared with the control group (1449.759 ± 156.586 MPa). SEM photographs of the present study shows gross increase in pitting roughness of the surface topography of all the three types of wires after four types of sterilization. Conclusion: Orthodontists who want to offer maximum safety for their patients can sterilize orthodontic wires before placement, as it does not deteriorate the tensile strength and surface roughness of the alloys. PMID:25210383

Method and apparatus for forming high-critical-temperature superconducting layers on flat and/or elongated substrates

DOEpatents

Ciszek, Theodore F.

1994-01-01

An elongated, flexible superconductive wire or strip is fabricated by pulling it through and out of a melt of metal oxide material at a rate conducive to forming a crystalline coating of superconductive metal oxide material on an elongated, flexible substrate wire or strip. A coating of crystalline superconductive material, such as Bi.sub.2 Sr.sub.2 CaCu.sub.2 O.sub.8, is annealed to effect conductive contact between adjacent crystalline structures in the coating material, which is then cooled to room temperature. The container for the melt can accommodate continuous passage of the substrate through the melt. Also, a second pass-through container can be used to simultaneously anneal and overcoat the superconductive coating with a hot metallic material, such as silver or silver alloy. A hollow, elongated tube casting method of forming an elongated, flexible superconductive wire includes drawing the melt by differential pressure into a heated tubular substrate.

Method and apparatus for forming high-critical-temperature superconducting layers on flat and/or elongated substrates

DOEpatents

Ciszek, T.F.

1994-04-19

An elongated, flexible superconductive wire or strip is fabricated by pulling it through and out of a melt of metal oxide material at a rate conducive to forming a crystalline coating of superconductive metal oxide material on an elongated, flexible substrate wire or strip. A coating of crystalline superconductive material, such as Bi[sub 2]Sr[sub 2]CaCu[sub 2]O[sub 8], is annealed to effect conductive contact between adjacent crystalline structures in the coating material, which is then cooled to room temperature. The container for the melt can accommodate continuous passage of the substrate through the melt. Also, a second pass-through container can be used to simultaneously anneal and overcoat the superconductive coating with a hot metallic material, such as silver or silver alloy. A hollow, elongated tube casting method of forming an elongated, flexible superconductive wire includes drawing the melt by differential pressure into a heated tubular substrate. 8 figures.

Experimental comparison and validation of hot-ball method with guarded hot plate method on polyurethane foams

NASA Astrophysics Data System (ADS)

Hudec, Ján; Glorieux, Christ; Dieška, Peter; Kubičár, Ľudovít

2016-07-01

The Hot-ball method is an innovative transient method for measuring thermophysical properties. The principle is based on heating of a small ball, incorporated in measured medium, by constant heating power and simultaneous measuring of the ball's temperature response since the heating was initiated. The shape of the temperature response depends on thermophysical properties of the medium, where the sensor is placed. This method is patented by Institute of Physics, SAS, where the method and sensors based on this method are being developed. At the beginning of the development of sensors for this method we were oriented on monitoring applications, where relative precision is much more important than accuracy. Meanwhile, the quality of sensors was improved good enough to be used for a new application - absolute measuring of thermophysical parameters of low thermally conductive materials. This paper describes experimental verification and validation of measurement by hot-ball method. Thanks to cooperation with Laboratory of Soft Matter and Biophysics of Catholic University of Leuven in Belgium, established Guarded Hot Plate method was used as a reference. Details about measuring setups, description of the experiments and results of the comparison are presented.

Rotating hot-wire investigation of the vortex responsible for blade-vortex interaction noise

NASA Technical Reports Server (NTRS)

Fontana, Richard Remo

1988-01-01

This distribution of the circumferential velocity of the vortex responsible for blade-vortex interaction noise was measured using a rotating hot-wire rake synchronously meshed with a model helicopter rotor at the blade passage frequency. Simultaneous far-field acoustic data and blade differential pressure measurements were obtained. Results show that the shape of the measured far-field acoustic blade-vortex interaction signature depends on the blade-vortex interaction geometry. The experimental results are compared with the Widnall-Wolf model for blade-vortex interaction noise.

Conversion from solvent rinsable fluxes to aqueous rinsable fluxes for hot oil solder leveling

NASA Astrophysics Data System (ADS)

1992-03-01

A water rinsable flux was evaluated for hot oil solder leveling of printed wiring boards. The previously used rosin-activated flux required a solvent containing a chlorinated hydrocarbon for removing the flux residues after soldering. The water rinsable flux requires hot water or a solution of hot detergent for removing flux residues after smoldering. The water rinsable flux produced an acceptable soldered surface. Flux residues were removed by either hot water (120 F) or a solution of hot detergent (120 F).

Current redistribution and generation of kinetic energy in the stagnated Z pinch.

PubMed

Ivanov, V V; Anderson, A A; Papp, D; Astanovitskiy, A L; Talbot, B R; Chittenden, J P; Niasse, N

2013-07-01

The structure of magnetic fields was investigated in stagnated wire-array Z pinches using a Faraday rotation diagnostic at the wavelength of 266 nm. The distribution of current in the pinch and trailing material was reconstructed. A significant part of current can switch from the main pinch to the trailing plasma preheated by x-ray radiation of the pinch. Secondary implosions of trailing plasma generate kinetic energy and provide enhanced heating and radiation of plasma at stagnation. Hot spots in wire-array Z pinches also provide enhanced radiation of the Z pinch. A collapse of a single hot spot radiates 1%-3% of x-ray energy of the Z pinch with a total contribution of hot spots of 10%-30%.

New devices for flow measurements: Hot film and burial wire sensors, infrared imagery, liquid crystal, and piezo-electric model

NASA Technical Reports Server (NTRS)

Mcree, Griffith J., Jr.; Roberts, A. Sidney, Jr.

1991-01-01

An experimental program aimed at identifying areas in low speed aerodynamic research where infrared imaging systems can make significant contributions is discussed. Implementing a new technique, a long electrically heated wire was placed across a laminar flow. By measuring the temperature distribution along the wire with the IR imaging camera, the flow behavior was identified.

Investigation of Axial Electric Field Measurements with Grounded-Wire TEM Surveys

NASA Astrophysics Data System (ADS)

Zhou, Nan-nan; Xue, Guo-qiang; Li, Hai; Hou, Dong-yang

2018-01-01

The grounded-wire transient electromagnetic (TEM) surveying is often performed along the equatorial direction with its observation lines paralleling to the transmitting wire with a certain transmitter-receiver distance. However, such method takes into account only the equatorial component of the electromagnetic field, and a little effort has been made on incorporating the other major component along the transmitting wire, here denoted as axial field. To obtain a comprehensive understanding of its fundamental characteristics and guide the designing of the corresponding observation system for reliable anomaly detection, this study for the first time investigates the axial electric field from three crucial aspects, including its decay curve, plane distribution, and anomaly sensitivity, through both synthetic modeling and real application to one major coal field in China. The results demonstrate a higher sensitivity to both high- and low-resistivity anomalies by the electric field in axial direction and confirm its great potentials for robust anomaly detection in the subsurface.

FireWire: Hot New Multimedia Interface or Flash in the Pan?

ERIC Educational Resources Information Center

Learn, Larry L., Ed.

1995-01-01

Examines potential solutions to the problem of personal computer cabling and configuration and serial port performance, namely "FireWire" (P1394) and "Universal Serial Bus" (USB). Discusses interface design, technical capabilities, user friendliness, compatibility, costs, and future perspectives. (AEF)

Alternative methods for C.R.A pipeline welding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belloni, A.

1996-12-01

The application of the GTAW process for C.R.A. (Corrosion Resistant Alloy) linepipe welding is a well known practice, nevertheless the high construction costs associated to the use of this process particularly for root pass welding (low welding speed) necessitate consideration of an updated version of the GMAW process (higher welding speed) for the same application. The present paper describes the progress obtained in using alternative welding methods to GTAW Cold wire such as: GTAW hot wire and GMAW to increase the welding speed and consequently reduce the overall project cost. The authors feel that this approach is essential to increasemore » the pipelaying productivity of a C.R.A. linepipe materials, at present still too far from that of the Carbon steel one.« less

A Thermal Analysis of a Hot-Wire Probe for Icing Applications

NASA Technical Reports Server (NTRS)

Struk, Peter M.; Rigby, David L.; Venkataraman, Krishna

2014-01-01

This paper presents a steady-state thermal model of a hot-wire instrument applicable to atmospheric measurement of water content in clouds. In this application, the power required to maintain the wire at a given temperature is used to deduce the water content of the cloud. The model considers electrical resistive heating, axial conduction, convection to the flow, radiation to the surroundings, as well as energy loss due to the heating, melting, and evaporation of impinging liquid and or ice. All of these parameters can be varied axially along the wire. The model further introduces a parameter called the evaporation potential which locally gauges the maximum fraction of incoming water that evaporates. The primary outputs of the model are the steady-state power required to maintain a spatially-average constant temperature as well as the variation of that temperature and other parameters along the wire. The model is used to understand the sensitivity of the hot-wire performance to various flow and boundary conditions including a detailed comparison of dry air and wet (i.e. cloud-on) conditions. The steady-state power values are compared to experimental results from a Science Engineering Associates (SEA) Multi-Element probe, a commonly used water-content measurement instrument. The model results show good agreement with experiment for both dry and cloud-on conditions with liquid water content. For ice, the experimental measurements under read the actual water content due to incomplete evaporation and splashing. Model results, which account for incomplete evaporation, are still higher than experimental results where the discrepancy is attributed to splashing mass-loss which is not accounted in the model.

Scavenging high-voltage copper wire, a hazardous petty larceny.

PubMed

Himel, H N; Ahn, L C; Jones, K C; Edlich, R F

1992-01-01

With the current emphasis on recycling and the establishment of markets for sale of used copper wire, scavenging of copper wire from old buildings and equipment has become common. Although scavenging without permission constitutes theft, a more significant risk to the perpetrator is the potential for electrical burn injury in attempting to remove "hot" wire. A severe high-voltage electrical burn injury sustained while attempting to scavenge wire from an old house is reported. The circumstances surrounding the injury, the clinical management of the case, and the long-term consequences to the patient are presented and discussed.

Verification and Validation of a Coordinate Transformation Method in Axisymmetric Transient Magnetics.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ashcraft, C. Chace; Niederhaus, John Henry; Robinson, Allen C.

We present a verification and validation analysis of a coordinate-transformation-based numerical solution method for the two-dimensional axisymmetric magnetic diffusion equation, implemented in the finite-element simulation code ALEGRA. The transformation, suggested by Melissen and Simkin, yields an equation set perfectly suited for linear finite elements and for problems with large jumps in material conductivity near the axis. The verification analysis examines transient magnetic diffusion in a rod or wire in a very low conductivity background by first deriving an approximate analytic solution using perturbation theory. This approach for generating a reference solution is shown to be not fully satisfactory. A specializedmore » approach for manufacturing an exact solution is then used to demonstrate second-order convergence under spatial refinement and tem- poral refinement. For this new implementation, a significant improvement relative to previously available formulations is observed. Benefits in accuracy for computed current density and Joule heating are also demonstrated. The validation analysis examines the circuit-driven explosion of a copper wire using resistive magnetohydrodynamics modeling, in comparison to experimental tests. The new implementation matches the accuracy of the existing formulation, with both formulations capturing the experimental burst time and action to within approximately 2%.« less

Pyrotechnic Smoke Compositions Containing Boron Carbide

DTIC Science & Technology

2012-06-10

resulting smoke. The inhalation of zinc fumes is known to cause “metal fume fever” and the smoke also contains various chlorinated organic compounds...matches were used to ignite the slurried items. Bare pellets were ignited with electrically heated nickel- chromium wire (hot wire). Small HC smoke

Injection deep level transient spectroscopy: An improved method for measuring capture rates of hot carriers in semiconductors

DOE PAGES

Fleming, R. M.; Seager, C. H.; Lang, D. V.; ...

2015-07-02

In this study, an improved method for measuring the cross sections for carrier trapping at defects in semiconductors is described. This method, a variation of deep level transient spectroscopy(DLTS) used with bipolar transistors, is applied to hot carrier trapping at vacancy-oxygen, carbon-oxygen, and three charge states of divacancy centers (V 2) in n- and p-type silicon. Unlike standard DLTS, we fill traps by injecting carriers into the depletion region of a bipolar transistor diode using a pulse of forward bias current applied to the adjacent diode. We show that this technique is capable of accurately measuring a wide range ofmore » capture cross sections at varying electric fields due to the control of the carrier density it provides. Because this technique can be applied to a variety of carrier energy distributions, it should be valuable in modeling the effect of radiation-induced generation-recombination currents in bipolar devices.« less

Fan broadband interaction noise modeling using a low-order method

NASA Astrophysics Data System (ADS)

Grace, S. M.

2015-06-01

A low-order method for simulating broadband interaction noise downstream of the fan stage in a turbofan engine is explored in this paper. The particular noise source of interest is due to the interaction of the fan rotor wake with the fan exit guide vanes (FEGVs). The vanes are modeled as flat plates and the method utilizes strip theory relying on unsteady aerodynamic cascade theory at each strip. This paper shows predictions for 6 of the 9 cases from NASA's Source Diagnostic Test (SDT) and all 4 cases from the 2014 Fan Broadband Workshop Fundamental Case 2 (FC2). The turbulence in the rotor wake is taken from hot-wire data for the low speed SDT cases and the FC2 cases. Additionally, four different computational simulations of the rotor wake flow for all of the SDT rotor speeds have been used to determine the rotor wake turbulence parameters. Comparisons between predictions based on the different inputs highlight the possibility of a potential effect present in the hot-wire data for the SDT as well as the importance of accurately describing the turbulence length scale when using this model. The method produces accurate predictions of the spectral shape for all of the cases. It also predicts reasonably well all of the trends that can be considered based on the included cases such as vane geometry, vane count, turbulence level, and rotor speed.

Deposition of thermal and hot-wire chemical vapor deposition copper thin films on patterned substrates.

PubMed

Papadimitropoulos, G; Davazoglou, D

2011-09-01

In this work we study the hot-wire chemical vapor deposition (HWCVD) of copper films on blanket and patterned substrates at high filament temperatures. A vertical chemical vapor deposition reactor was used in which the chemical reactions were assisted by a tungsten filament heated at 650 degrees C. Hexafluoroacetylacetonate Cu(I) trimethylvinylsilane (CupraSelect) vapors were used, directly injected into the reactor with the aid of a liquid injection system using N2 as carrier gas. Copper thin films grown also by thermal and hot-wire CVD. The substrates used were oxidized silicon wafers on which trenches with dimensions of the order of 500 nm were formed and subsequently covered with LPCVD W. HWCVD copper thin films grown at filament temperature of 650 degrees C showed higher growth rates compared to the thermally ones. They also exhibited higher resistivities than thermal and HWCVD films grown at lower filament temperatures. Thermally grown Cu films have very uniform deposition leading to full coverage of the patterned substrates while the HWCVD films exhibited a tendency to vertical growth, thereby creating gaps and incomplete step coverage.

Measurements of multi-scalar mixing in a turbulent coaxial jet

NASA Astrophysics Data System (ADS)

Hewes, Alais; Mydlarski, Laurent

2017-11-01

There are relatively few studies of turbulent multi-scalar mixing, despite the occurrence of this phenomenon in common processes (e.g. chemically reacting flows, oceanic mixing). In the present work, we simultaneously measure the evolution of two passive scalars (temperature and helium concentration) and velocity in a coaxial jet. Such a flow is particularly relevant, as coaxial jets are regularly employed in applications of turbulent non-premixed combustion, which relies on multi-scalar mixing. The coaxial jet used in the current experiment is based on the work of Cai et al. (J. Fluid Mech., 2011), and consists of a vertically oriented central jet of helium and air, surrounded by an annular flow of (unheated) pure air, emanating into a slow co-flow of (pure) heated air. The simultaneous two-scalar and velocity measurements are made using a 3-wire hot-wire anemometry probe. The first two wires of this probe form an interference (or Way-Libby) probe, and measure velocity and concentration. The third wire, a hot-wire operating at a low overheat ratio, measures temperature. The 3-wire probe is used to obtain concurrent velocity, concentration, and temperature statistics to characterize the mixing process by way of single and multivariable/joint statistics. Supported by the Natural Sciences and Engineering Research Council of Canada (Grant 217184).

[Osteosynthesis by tension band wiring of displaced fractures of the olecranon].

PubMed

Doursounian, L; Prevot, O; Touzard, R C

1994-01-01

Fifty-two displaced olecranon fractures in adults were treated over a 5-year period. Minimum follow-up was 6 months. Forty-eight fractures were operated and 38 were treated by tension band wiring technique. This technique, applied for all types of fractures, gave good functional results in 33 cases (87%) and fair functional results in 5 cases. Complications include 1 pseudarthrosis, 2 loss of reduction, 2 transient tourniquet palsy and 13 skin problems due to wire protrusion. Tension band wiring is a simple safe and effective technique for displaced olecranon fractures but often requires K-wire removal.

Temperature measuring device

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lauf, R.J.; Bible, D.W.; Sohns, C.W.

1999-10-19

Systems and methods are described for a wireless instrumented silicon wafer that can measure temperatures at various points and transmit those temperature readings to an external receiver. The device has particular utility in the processing of semiconductor wafers, where it can be used to map thermal uniformity on hot plates, cold plates, spin bowl chucks, etc. without the inconvenience of wires or the inevitable thermal perturbations attendant with them.

Temperature measuring device

DOEpatents

Lauf, Robert J.; Bible, Don W.; Sohns, Carl W.

1999-01-01

Systems and methods are described for a wireless instrumented silicon wafer that can measure temperatures at various points and transmit those temperature readings to an external receiver. The device has particular utility in the processing of semiconductor wafers, where it can be used to map thermal uniformity on hot plates, cold plates, spin bowl chucks, etc. without the inconvenience of wires or the inevitable thermal perturbations attendant with them.

An investigation of nonsimultaneous laser-induced fluorescence

NASA Technical Reports Server (NTRS)

Fletcher, D. G.

1993-01-01

An alternative to simultaneous, two-line laser-induced fluorescence for thermodynamic property measurement is presented. This spectroscopic approach is similar to multiple-overheat hot-wire anemometry and is based on laser excitation of different fluorescence transitions for separate, sequential wind tunnel runs. Both fluctuating and mean thermodynamic property measurements seem to be achievable with this method without exciting the transitions during the same laser pulse.

Transient hot-film sensor response in a shock tube

NASA Technical Reports Server (NTRS)

Roberts, A. S., Jr.; Ortgies, K. R.; Gartenberg, E.

1989-01-01

Shock tube experiments were performed to determine the response of a hot-film sensor, mounted flush on the side wall of a shock tube, to unsteady flow behind a normal shock wave. The present experiments attempt to isolate the response of the anemometer due only to the change in convective heat transfer at the hot-film surface. The experiments, performed at low supersonic shock speeds in air, are described along with the data acquisition procedure. The change in convective heat transfer is deduced from the data and the results are compared with those from transient boundary layer theory and another set of experimental results. Finally, a transient local heat transfer coefficient is formulated for use as the forcing function in a hot-film sensor instrument model simulation.

The flying hot wire and related instrumentation

NASA Technical Reports Server (NTRS)

Coles, D.; Cantnell, B.; Wadcock, A.

1978-01-01

A flying hot-wire technique is proposed for studies of separated turbulent flow in wind tunnels. The technique avoids the problem of signal rectification in regions of high turbulence level by moving the probe rapidly through the flow on the end of a rotating arm. New problems which arise include control of effects of torque variation on rotor speed, avoidance of interference from the wake of the moving arms, and synchronization of data acquisition with rotation. Solutions for these problems are described. The self-calibrating feature of the technique is illustrated by a sample X-array calibration.

Improved Apparatus for the Measurement of Fluctuations of Air Speed in Turbulent Flow

NASA Technical Reports Server (NTRS)

Mock, W C , Jr; Dryden, H L

1934-01-01

This report describes recent improvements in the design of the equipment associated with the hot-wire anemometer for the measurement of fluctuating air speeds in turbulent air flow, and presents the results of some experimental investigations dealing with the response of the hot wire to speed fluctuations of various frequencies. Attempts at measuring the frequency of the fluctuations encountered in the Bureau of Standards' 54-inch wind tunnel are also reported. In addition, the difficulties encountered in the use of such apparatus and the precautions found helpful in avoiding them are discussed.

Two-Flux and Green's Function Method for Transient Radiative Transfer in a Semi-Transparent Layer

NASA Technical Reports Server (NTRS)

Siegel, Robert

1995-01-01

A method using a Green's function is developed for computing transient temperatures in a semitransparent layer by using the two-flux method coupled with the transient energy equation. Each boundary of the layer is exposed to a hot or cold radiative environment, and is heated or cooled by convection. The layer refractive index is larger than one, and the effect of internal reflections is included with the boundaries assumed diffuse. The analysis accounts for internal emission, absorption, heat conduction, and isotropic scattering. Spectrally dependent radiative properties are included, and transient results are given to illustrate two-band spectral behavior with optically thin and thick bands. Transient results using the present Green's function method are verified for a gray layer by comparison with a finite difference solution of the exact radiative transfer equations; excellent agreement is obtained. The present method requires only moderate computing times and incorporates isotropic scattering without additional complexity. Typical temperature distributions are given to illustrate application of the method by examining the effect of strong radiative heating on one side of a layer with convective cooling on the other side, and the interaction of strong convective heating with radiative cooling from the layer interior.

Interaction of an Artificially Thickened Boundary Layer with a Vertically Mounted Pitching Airfoil

NASA Astrophysics Data System (ADS)

Hohman, Tristen; Smits, Alexander; Martinelli, Luigi

2011-11-01

Wind energy represents a large portion of the growing market in alternative energy technologies and the current landscape has been dominated by the more prevalent horizontal axis wind turbine. However, there are several advantages to the vertical axis wind turbine (VAWT) or Darrieus type design and yet there is much to be understood about how the atmospheric boundary layer (ABL) affects their performance. In this study the ABL was simulated in a wind tunnel through the use of elliptical shaped vortex generators, a castellated wall, and floor roughness elements as described in the method of Counihan (1967) and then verified its validity by hot wire measurement of the mean velocity profile as well as the turbulence intensity. The motion of an blade element around a vertical axis is approximated through the use of a pitching airfoil. The wake of the airfoil is investigated through hot wire anemometry in both uniform flow and in the simulated boundary layer both at Re = 1 . 37 ×105 based on the chord of the airfoil. Sponsored by Hopewell Wind Power (Hong Kong) Limited.

A momentum source model for wire-wrapped rod bundles—Concept, validation, and application

DOE PAGES

Hu, Rui; Fanning, Thomas H.

2013-06-19

Large uncertainties still exist in the treatment of wire-spacers and drag models for momentum transfer in current lumped parameter models. Here, to improve the hydraulic modeling of wire-wrap spacers in a rod bundle, a three-dimensional momentum source model (MSM) has been developed to model the anisotropic flow without the need to resolve the geometric details of the wire-wraps. The MSM is examined for 7-pin and 37-pin bundles steady-state simulations using the commercial CFD code STAR-CCM+. The calculated steady-state inter-subchannel cross flow velocities match very well in comparisons between bare bundles with the MSM applied and the wire-wrapped bundles with explicitmore » geometry. The validity of the model is further verified by mesh and parameter sensitivity studies. Furthermore, the MSM is applied to a 61-pin EBR-II experimental subassembly for both steady state and PLOF transient simulations. Reasonably accurate predictions of temperature, pressure, and fluid flow velocities have been achieved using the MSM for both steady-state and transient conditions. Significant computing resources are saved with the MSM since it can be used on a much coarser computational mesh.« less

Shape memory alloy heat engines and energy harvesting systems

DOEpatents

Browne, Alan L; Johnson, Nancy L; Shaw, John Andrew; Churchill, Christopher Burton; Keefe, Andrew C; McKnight, Geoffrey P; Alexander, Paul W; Herrera, Guillermo A; Yates, James Ryan; Brown, Jeffrey W

2014-09-30

A heat engine includes a first rotatable pulley and a second rotatable pulley spaced from the first rotatable pulley. A shape memory alloy (SMA) element is disposed about respective portions of the pulleys at an SMA pulley ratio. The SMA element includes a first wire, a second wire, and a matrix joining the first wire and the second wire. The first wire and the second wire are in contact with the pulleys, but the matrix is not in contact with the pulleys. A timing cable is disposed about respective portions of the pulleys at a timing pulley ratio, which is different than the SMA pulley ratio. The SMA element converts a thermal energy gradient between the hot region and the cold region into mechanical energy.

Fragmentation of Thin Wires under High Voltage Pulses and Bipolar Fusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Papageorgiou, C. D.; Raptis, T. E.

2010-01-21

In this article we present an alternative explanation of the phenomenon of wire fragmentation under high transient currents based on classical electromagnetism. We also explain how this phenomenon can be utilized as a primitive example of low energy-high power disruptive phenomena that can affect even nuclear matter.

Explosive component acceptance tester using laser interferometer technology

NASA Technical Reports Server (NTRS)

Wickstrom, Richard D.; Tarbell, William W.

1993-01-01

Acceptance testing of explosive components requires a reliable and simple to use testing method that can discern less than optimal performance. For hot-wire detonators, traditional techniques use dent blocks or photographic diagnostic methods. More complicated approaches are avoided because of their inherent problems with setup and maintenance. A recently developed tester is based on using a laser interferometer to measure the velocity of flying plates accelerated by explosively actuated detonators. Unlike ordinary interferometers that monitor displacement of the test article, this device measures velocity directly and is commonly used with non-spectral surfaces. Most often referred to as the VISAR technique (Velocity Interferometer System for Any Reflecting Surface), it has become the most widely-accepted choice for accurate measurement of velocity in the range greater than 1 mm/micro-s. Traditional VISAR devices require extensive setup and adjustment and therefore are unacceptable in a production-testing environment. This paper describes a new VISAR approach which requires virtually no adjustments, yet provides data with accuracy comparable to the more complicated systems. The device, termed the Fixed-Cavity VISAR, is currently being developed to serve as a product verification tool for hot-wire detonators and slappers. An extensive data acquisition and analysis computer code was also created to automate the manipulation of raw data into final results.

A Survey of Measurements and Measuring Techniques in Rapidly Distorted Compressible Turbulent Boundary Layers

DTIC Science & Technology

1989-05-01

between the two vertically separated wires closer to the wall. This indicates that the structure becomes less coherent closer to the wall sgain explaining...bibliography prepared by Freymuth (1978), and the application of hot- wire anemometry to subsonic flows has been systematicallv researched since that time...the wire and through the prongs modifies the frequency response of the sensor . Steps in the amplitude Bode diagram can occur, similar to those arising

Channel Wall Nozzle Hot-fire Tests

NASA Image and Video Library

2018-03-16

A subscale channel wall nozzle is hot-fire tested in November 2017 at NASA's Marshall Space Flight Center. The nozzle was fabricated using three separate, state-of-the-art, advanced manufacturing technologies including a new process called Laser Wire Direct Closeout that was co-developed and advanced at Marshall.

Instrument for Aircraft-Icing and Cloud-Physics Measurements

NASA Technical Reports Server (NTRS)

Lilie, Lyle; Bouley, Dan; Sivo, Chris

2006-01-01

The figure shows a compact, rugged, simple sensor head that is part of an instrumentation system for making measurements to characterize the severity of aircraft-icing conditions and/or to perform research on cloud physics. The quantities that are calculated from measurement data acquired by this system and that are used to quantify the severity of icing conditions include sizes of cloud water drops, cloud liquid water content (LWC), cloud ice water content (IWC), and cloud total water content (TWC). The sensor head is mounted on the outside of an aircraft, positioned and oriented to intercept the ambient airflow. The sensor head consists of an open housing that is heated in a controlled manner to keep it free of ice and that contains four hot-wire elements. The hot-wire sensing elements have different shapes and sizes and, therefore, exhibit different measurement efficiencies with respect to droplet size and water phase (liquid, frozen, or mixed). Three of the hot-wire sensing elements are oriented across the airflow so as to intercept incoming cloud water. For each of these elements, the LWC or TWC affects the power required to maintain a constant temperature in the presence of cloud water.

Wavelet-like bases for thin-wire integral equations in electromagnetics

NASA Astrophysics Data System (ADS)

Francomano, E.; Tortorici, A.; Toscano, E.; Ala, G.; Viola, F.

2005-03-01

In this paper, wavelets are used in solving, by the method of moments, a modified version of the thin-wire electric field integral equation, in frequency domain. The time domain electromagnetic quantities, are obtained by using the inverse discrete fast Fourier transform. The retarded scalar electric and vector magnetic potentials are employed in order to obtain the integral formulation. The discretized model generated by applying the direct method of moments via point-matching procedure, results in a linear system with a dense matrix which have to be solved for each frequency of the Fourier spectrum of the time domain impressed source. Therefore, orthogonal wavelet-like basis transform is used to sparsify the moment matrix. In particular, dyadic and M-band wavelet transforms have been adopted, so generating different sparse matrix structures. This leads to an efficient solution in solving the resulting sparse matrix equation. Moreover, a wavelet preconditioner is used to accelerate the convergence rate of the iterative solver employed. These numerical features are used in analyzing the transient behavior of a lightning protection system. In particular, the transient performance of the earth termination system of a lightning protection system or of the earth electrode of an electric power substation, during its operation is focused. The numerical results, obtained by running a complex structure, are discussed and the features of the used method are underlined.

Convective response of a wall-mounted hot-film sensor in a shock tube

NASA Technical Reports Server (NTRS)

Roberts, A. Sidney, Jr.; Ortgies, Kelly R.; Gartenberg, Ehud; Carraway, Debra L.

1991-01-01

Shock tube experiments were performed in order to determine the response of a single hot-film element of a sensor array to transiently induced flow behind weak normal shock waves. The experiments attempt to isolate the response due only to the change in convective heat transfer at the hot-film surface mounted on the wall of the shock tube. The experiments are described, the results being correlated with transient boundary layer theory and compared with an independent set of experimental results. One of the findings indicates that the change in the air properties (temperature and pressure) precedes the air mass transport, causing an ambiguity in the sensor response to the development of the velocity boundary layer. Also, a transient, local heat transfer coefficient is formulated to be used as a forcing function in an hot-film instrument model and simulation which remains under investigation.

Asbestos and Inconel combined to form hot-gas seal

NASA Technical Reports Server (NTRS)

Wooster, C. W., Jr.

1968-01-01

Hot-gas seal prevents warpage tendencies in large flange joints exposed to high temperatures, such as those present in large space vehicle engine exhausts. Two Inconel wire mesh cores are held in place by an asbestos cloth cover that acts as a spacer to form the seal.

Effects of finite hot-wire spatial resolution on turbulence statistics and velocity spectra in a round turbulent free jet

NASA Astrophysics Data System (ADS)

Sadeghi, Hamed; Lavoie, Philippe; Pollard, Andrew

2018-03-01

The effect of finite hot-wire spatial resolution on turbulence statistics and velocity spectra in a round turbulent free jet is investigated. To quantify spatial resolution effects, measurements were taken using a nano-scale thermal anemometry probe (NSTAP) and compared to results from conventional hot-wires with sensing lengths of l=0.5 and 1 mm. The NSTAP has a sensing length significantly smaller than the Kolmogorov length scale η for the present experimental conditions, whereas the sensing lengths for the conventional probes are larger than η. The spatial resolution is found to have a significant impact on the dissipation both on and off the jet centreline with the NSTAP results exceeding those obtained from the conventional probes. The resolution effects along the jet centreline are adequately predicted using a Wyngaard-type spectral technique (Wyngaard in J Sci Instr 1(2):1105-1108,1968), but additional attenuation on the measured turbulence quantities are observed off the centreline. The magnitude of this attenuation is a function of both the ratio of wire length to Kolmogorov length scale and the magnitude of the shear. The effect of spatial resolution is noted to have an impact on the power-law decay parameters for the turbulent kinetic energy that is computed. The effect of spatial filtering on the streamwise dissipation energy spectra is also considered. Empirical functions are proposed to estimate the effect of finite resolution, which take into account the mean shear.

Measurement of Thermal Conductivity of Porcine Liver in the Temperature Range of Cryotherapy and Hyperthermia (250~315k) by A Thermal Sensor Made of A Micron-Scale Enameled Copper Wire.

PubMed

Jiang, Z D; Zhao, G; Lu, G R

　　BACKGROUND: Cryotherapy and hyperthermia are effective treatments for several diseases, especially for liver cancers. Thermal conductivity is a significant thermal property for the prediction and guidance of surgical procedure. However, the thermal conductivities of organs and tissues, especially over the temperature range of both cryotherapy and hyperthermia are scarce. To provide comprehensive thermal conductivity of liver for both cryotherapy and hyperthermia. A hot probe made of stain steel needle and micron-sized copper wire is used for measurement. To verify data processing, both the least square method and the Monte Carlo inversion method are used to determine the hot probe constants, respectively, with reference materials of water and 29.9 % Ca 2 Cl aqueous solution. Then the thermal conductivities of Hanks solution and pork liver bathed in Hanks solution are measured. The effective length for two methods is nearly the same, but the heat capacity of probe calibrated by the Monte Carlo inversion is temperature dependent. Fairly comprehensive thermal conductivity of porcine liver measured with these two methods in the target temperature range is verified to be similar. We provide an integrated thermal conductivity of liver for cryotherapy and hyperthermia in two methods, and make more accurate predictions possible for surgery. The least square method and the Monte Carlo inversion method have their advantages and disadvantages. The least square method is available for measurement of liquids that not prone to convection or solids in a wide temperature range, while the Monte Carlo inversion method is available for accurate and rapid measurement.

A Method for the Instantaneous Determination of the Velocity and Direction of the Wind

NASA Technical Reports Server (NTRS)

Huguenard, E; Magnan, A; Planiol, A

1924-01-01

The laboratory instruments, which we often constructed with makeshift means, gave encouraging results and showed that they could satisfactorily meet the required conditions. By limiting ourselves to the employment of hot wires of 0.05 mm (0.002 in.) diameter, we obtained instruments which faithfully followed all the wind fluctuations of over 0.1 second and even much more rapid variations without any very great error.

Turbulence Characteristics of Swirling Flowfields. Ph.D. Thesis

NASA Technical Reports Server (NTRS)

Jackson, T. W.

1983-01-01

Combustor design phenomena; recirculating flows research; single-wire, six-orientation, eddy dissipation rate, and turbulence modeling measurement; directional sensitivity (DS); calibration equipment, confined jet facility, and hot-wire instrumentation; effects of swirl, strong contraction nozzle, and expansion ratio; and turbulence parameters; uncertain; and DS in laminar jets; turbulent nonswirling jets, and turbulent swirling jets are discussed.

Method of Generating Transient Equivalent Sink and Test Target Temperatures for Swift BAT

NASA Technical Reports Server (NTRS)

Choi, Michael K.

2004-01-01

The NASA Swift mission has a 600-km altitude and a 22 degrees maximum inclination. The sun angle varies from 45 degrees to 180 degrees in normal operation. As a result, environmental heat fluxes absorbed by the Burst Alert Telescope (BAT) radiator and loop heat pipe (LHP) compensation chambers (CCs) vary transiently. Therefore the equivalent sink temperatures for the radiator and CCs varies transiently. In thermal performance verification testing in vacuum, the radiator and CCs radiated heat to sink targets. This paper presents an analytical technique for generating orbit transient equivalent sink temperatures and a technique for generating transient sink target temperatures for the radiator and LHP CCs. Using these techniques, transient target temperatures for the radiator and LHP CCs were generated for three thermal environmental cases: worst hot case, worst cold case, and cooldown and warmup between worst hot case in sunlight and worst cold case in the eclipse, and three different heat transport values: 128 W, 255 W, and 382 W. The 128 W case assumed that the two LHPs transport 255 W equally to the radiator. The 255 W case assumed that one LHP fails so that the remaining LHP transports all the waste heat from the detector array to the radiator. The 382 W case assumed that one LHP fails so that the remaining LHP transports all the waste heat from the detector array to the radiator, and has a 50% design margin. All these transient target temperatures were successfully implemented in the engineering test unit (ETU) LHP and flight LHP thermal performance verification tests in vacuum.

Evaluation of tensile strength and surface topography of orthodontic wires after infection control procedures: An in vitro study.

PubMed

Brindha, M; Kumaran, N Kurunji; Rajasigamani, K

2014-07-01

The aim of this study is to evaluate, the influence of four types of sterilization/disinfection procedures (autoclave, hot air oven, glutaraldehyde, and ultraviolet [UV] light) on the tensile strength and surface topography of three orthodontic wires (stainless steel (SS), titanium - molybdenum alloy [TMA], and cobalt chromium (CoCr)). Sample comprised of three types of 8 inches straight length segments of orthodontic wires. They were divided into three groups according to wire composition comprising of 50 samples each. Totally 50 samples of each group were then equally divided into five subgroups according to sterilization method. After sterilization and disinfection of the experimental group, surface topography was examined with scanning electron microscope (SEM) and tensile strength was tested using universal testing machine. The results of this study show that the mean ultimate tensile strength (UTS) of SS wire after four sterilization procedures were similar to the control group (1845.815 ± 142.29 MPa). The mean UTS of TMA wire increases after four sterilization procedures when compared with the control group (874.107 ± 275.939 MPa). The mean UTS of CoCr wire remains same after UV light disinfection, but increases after other three sterilization procedures when compared with the control group (1449.759 ± 156.586 MPa). SEM photographs of the present study shows gross increase in pitting roughness of the surface topography of all the three types of wires after four types of sterilization. Orthodontists who want to offer maximum safety for their patients can sterilize orthodontic wires before placement, as it does not deteriorate the tensile strength and surface roughness of the alloys.

Present status of PIT round wires of 122-type iron-based superconductors

NASA Astrophysics Data System (ADS)

Tamegai, T.; Suwa, T.; Pyon, S.; Kajitani, H.; Takano, K.; Koizumi, N.; Awaji, S.; Watanabe, K.

2017-12-01

Outstanding characteristics with high T c and H c2 and small anisotropy in iron-based superconductors (IBSs) have triggered the development of superconducting wires and tapes using these novel superconductors. In this short article, developments and present status of round wires of 122-type IBSs are reviewed. By introducing hot-isostatic pressing (HIP) technique, J c in round wires of 122-type IBSs has been improved significantly. Further improvements have been realized by refining the fabrication process of the core material and introducing partial texturing of the wire core. The largest transport J c for round wires at 4.2 K at self-field and 100 kOe are 2.0x105 A/cm2 and 3.8x104 A/cm2, respectively. We also compare the J c characteristics of wires and tapes processed by HIP.

Modelling transient temperature distribution for injecting hot water through a well to an aquifer thermal energy storage system

NASA Astrophysics Data System (ADS)

Yang, Shaw-Yang; Yeh, Hund-Der; Li, Kuang-Yi

2010-10-01

Heat storage systems are usually used to store waste heat and solar energy. In this study, a mathematical model is developed to predict both the steady-state and transient temperature distributions of an aquifer thermal energy storage (ATES) system after hot water is injected through a well into a confined aquifer. The ATES has a confined aquifer bounded by aquicludes with different thermomechanical properties and geothermal gradients along the depth. Consider that the heat is transferred by conduction and forced convection within the aquifer and by conduction within the aquicludes. The dimensionless semi-analytical solutions of temperature distributions of the ATES system are developed using Laplace and Fourier transforms and their corresponding time-domain results are evaluated numerically by the modified Crump method. The steady-state solution is obtained from the transient solution through the final-value theorem. The effect of the heat transfer coefficient on aquiclude temperature distribution is appreciable only near the outer boundaries of the aquicludes. The present solutions are useful for estimating the temperature distribution of heat injection and the aquifer thermal capacity of ATES systems.

Walks of bubbles on a hot wire in a liquid bath

NASA Astrophysics Data System (ADS)

Duchesne, A.; Caps, H.

2017-05-01

When a horizontal resistive wire is heated up to the boiling point in a subcooled liquid bath, some vapor bubbles nucleate on its surface. The traditional nucleate boiling theory predicts that bubbles generated from active nucleate sites grow up and depart from the heating surface due to buoyancy and inertia. However, we observed here a different behavior: the bubbles slide along the heated wire. In this situation, unexpected regimes are observed; from the simple sliding motion to bubble clustering. We noticed that bubbles could rapidly change their moving direction and may also interact. Finally, we propose an interpretation for both the attraction between the bubbles and the wire and for the motion of the bubbles on the wire in terms of Marangoni effects.

Landing Gear Components Noise Study - PIV and Hot-Wire Measurements

NASA Technical Reports Server (NTRS)

Hutcheson, Florence V.; Burley, Casey L.; Stead, Daniel J.; Becker, Lawrence E.; Price, Jennifer L.

2010-01-01

PIV and hot-wire measurements of the wake flow from rods and bars are presented. The test models include rods of different diameters and cross sections and a rod juxtaposed to a plate. The latter is representative of the latch door that is attached to an aircraft landing gear when the gear is deployed, while the single and multiple rod configurations tested are representative of some of the various struts and cables configuration present on an aircraft landing gear. The test set up is described and the flow measurements are presented. The effect of model surface treatment and freestream turbulence on the spanwise coherence of the vortex shedding is studied for several rod and bar configurations.

Analysis of acoustic and entropy disturbances in a hypersonic wind tunnel

NASA Astrophysics Data System (ADS)

Schilden, Thomas; Schröder, Wolfgang; Ali, Syed Raza Christopher; Schreyer, Anne-Marie; Wu, Jie; Radespiel, Rolf

2016-05-01

The tunnel noise in a Mach 5.9 Ludwieg tube is determined by two methods, a newly developed cone-probe-DNS method and a reliable hot-wire-Pitot-probe method. The new method combines pressure and heat flux measurements using a cone probe and direct numerical simulation (DNS). The modal analysis is based on transfer functions obtained by the DNS to link the measured quantities to the tunnel noise. The measurements are performed for several unit-Reynolds numbers in the range of 5 ṡ 106 ≤ Re/m ≤ 16 ṡ 106 and probe positions to identify the sensitivities of tunnel noise. The DNS solutions show similar response mechanisms of the cone probe to incident acoustic and entropy waves which leads to high condition numbers of the transfer matrix such that a unique relationship between response and source mechanism can be only determined by neglecting the contribution of the non-acoustic modes to the pressure and heat flux fluctuations. The results of the cone-probe-DNS method are compared to a modal analysis based on the hot-wire-Pitot-probe method which provides reliable results in the frequency range less than 50 kHz. In this low frequency range the findings of the two different mode analyses agree well. At higher frequencies, the newly developed cone-probe-DNS method is still valid. The tunnel noise is dominated by the acoustic mode, since the entropy mode is lower by one order of magnitude and the vorticity mode can be neglected. The acoustic mode is approximately 0.5% at 30 kHz and the cone-probe-DNS data illustrate the acoustic mode to decrease and to asymptotically approach 0.2%.

Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient.

PubMed

Hindasageri, V; Vedula, R P; Prabhu, S V

2013-02-01

Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

Thermocouple error correction for measuring the flame temperature with determination of emissivity and heat transfer coefficient

NASA Astrophysics Data System (ADS)

Hindasageri, V.; Vedula, R. P.; Prabhu, S. V.

2013-02-01

Temperature measurement by thermocouples is prone to errors due to conduction and radiation losses and therefore has to be corrected for precise measurement. The temperature dependent emissivity of the thermocouple wires is measured by the use of thermal infrared camera. The measured emissivities are found to be 20%-40% lower than the theoretical values predicted from theory of electromagnetism. A transient technique is employed for finding the heat transfer coefficients for the lead wire and the bead of the thermocouple. This method does not require the data of thermal properties and velocity of the burnt gases. The heat transfer coefficients obtained from the present method have an average deviation of 20% from the available heat transfer correlations in literature for non-reacting convective flow over cylinders and spheres. The parametric study of thermocouple error using the numerical code confirmed the existence of a minimum wire length beyond which the conduction loss is a constant minimal. Temperature of premixed methane-air flames stabilised on 16 mm diameter tube burner is measured by three B-type thermocouples of wire diameters: 0.15 mm, 0.30 mm, and 0.60 mm. The measurements are made at three distances from the burner tip (thermocouple tip to burner tip/burner diameter = 2, 4, and 6) at an equivalence ratio of 1 for the tube Reynolds number varying from 1000 to 2200. These measured flame temperatures are corrected by the present numerical procedure, the multi-element method, and the extrapolation method. The flame temperatures estimated by the two-element method and extrapolation method deviate from numerical results within 2.5% and 4%, respectively.

Industrial hygiene evaluation of thermal degradation products from PVC film in meat-wrapping operations.

PubMed

Cook, W A

1980-07-01

An industrial hygiene evaluation is presented concerning experimental data included in the preceding paper on thermal degradation products from hot-wire and "cool"-rod cutting of PVC film but, in this paper, limited to film used in meat-wrapping operations. Room air concentrations of less than 0.2 ppm HCl and less than 0.05 ppm benzene can be maintained by a number of factors, including minimal dilution ventilation. Estimates of room air concentrations of degradation products are presented using average values of amounts produced per cut. The relation of these concentrations to TLV's is given, together with methods of suggesting TLV's for substances not listed by ACGIH or OSHA. Room air concentrations for the 12 degradation products for which TLV's are assigned, based on average values per cut, were no greater than 0.3% of accepted limits. Room air concentrations of DOA are not determinable from available data but present information does not indicate that exposure to DOA causes airway hyperreactivity. The cool rod, rather than the hot wire, is recommended as good industrial hygiene practice, producing no apparent PVC degradation products, even though similar amounts of DOA are volatilized.

Structural, optical, opto-thermal and thermal properties of ZnS-PVA nanofluids synthesized through a radiolytic approach.

PubMed

Kharazmi, Alireza; Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra

2015-01-01

This work describes a fast, clean and low-cost approach to synthesize ZnS-PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV-visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated.

Double-sided laser beam welded T-joints for aluminum-lithium alloy aircraft fuselage panels: Effects of filler elements on microstructure and mechanical properties

NASA Astrophysics Data System (ADS)

Han, Bing; Tao, Wang; Chen, Yanbin; Li, Hao

2017-08-01

In the current work, T-joints consisting of 2.0 mm thick 2060-T8/2099-T83 aluminum-lithium alloys for aircraft fuselage panels have been fabricated by double-sided fiber laser beam welding with different filler wires. A new type wire CW3 (Al-6.2Cu-5.4Si) was studied and compared with conventional wire AA4047 (Al-12Si) mainly on microstructure and mechanical properties. It was found that the main combined function of Al-6.2%Cu-5.4%Si in CW3 resulted in considerable improvements especially on intergranular strength, hot cracking susceptibility and hoop tensile properties. Typical non-dendritic equiaxed zone (EQZ) was observed along welds' fusion boundary. Hot cracks and fractures during the load were always located within the EQZ, however, this typical zone could be restrained by CW3, effectively. Furthermore, changing of the main intergranular precipitated phase within the EQZ from T phase by AA4047 to T2 phase by CW3 also resulted in developments on microscopic intergranular reinforcement and macroscopic hoop tensile properties. In addition, bridging caused by richer substructure dendrites within CW3 weld's columnar zone resulted in much lower hot cracking susceptibility of the whole weld than AA4047.

Proceedings of the Workshop on the Chemical Suppression of Rocket Afterburning and of Gun Muzzle Flash

DTIC Science & Technology

1987-03-01

We report here the first results of this gun simulator used in the study of muzzle flash. The test setup used is shown in Figure 18. Pressure ports...experiments. For the first tests , the exploding wires mentioned above ignited the gas mixture. Later, "soft" ignition by means of a single tungsten...wire, placed axially in the chamber, was also tested . The voltage pulse applied across this hot wire is shown in Figure 19. This "soft" ignition

Prediction of Spin-Polarization Effects in Quantum Wire Transport

NASA Astrophysics Data System (ADS)

Fasol, Gerhard; Sakaki, Hiroyuki

1994-01-01

We predict a new effect for transport in quantum wires: spontaneous spin polarization. Most work on transport in mesoscopic devices has assumed a model of non interacting, spin-free electrons. We introduce spin, electron pair scattering and microscopic crystal properties into the design of mesoscopic devices. The new spin polarization effect results from the fact that in a single mode quantum wire, electron and hole bands still have two spin subbands. In general, these two spin subbands are expected to be split even in zero magnetic field. At sufficiently low temperatures the electron pair scattering rates for one spin subband ( e.g., the spin-down) can be much larger than for the other spin subband. This effect can be used for an active spin polarizer device: hot electrons in one subband ( e.g., `spin up') pass with weak pair scattering, while electrons in the opposite subband ( e.g., `spin down'), have high probability of scattering into the `spin-up' subband, resulting in spin polarization of a hot electron beam.

Time domain analysis of thin-wire antennas over lossy ground using the reflection-coefficient approximation

NASA Astrophysics Data System (ADS)

FernáNdez Pantoja, M.; Yarovoy, A. G.; Rubio Bretones, A.; GonzáLez GarcíA, S.

2009-12-01

This paper presents a procedure to extend the methods of moments in time domain for the transient analysis of thin-wire antennas to include those cases where the antennas are located over a lossy half-space. This extended technique is based on the reflection coefficient (RC) approach, which approximates the fields incident on the ground interface as plane waves and calculates the time domain RC using the inverse Fourier transform of Fresnel equations. The implementation presented in this paper uses general expressions for the RC which extend its range of applicability to lossy grounds, and is proven to be accurate and fast for antennas located not too near to the ground. The resulting general purpose procedure, able to treat arbitrarily oriented thin-wire antennas, is appropriate for all kind of half-spaces, including lossy cases, and it has turned out to be as computationally fast solving the problem of an arbitrary ground as dealing with a perfect electric conductor ground plane. Results show a numerical validation of the method for different half-spaces, paying special attention to the influence of the antenna to ground distance in the accuracy of the results.

Fabrication of an Aluminum Based Hot Electron Mixer for Terahertz Applications

NASA Technical Reports Server (NTRS)

Echternach, P. M.; LeDuc, H. G.; Skalare, A.; McGrath, W. R.

2000-01-01

Aluminum based diffusion cooled hot electron bolometers (HEB) mixers, predicted to have better noise, bandwidth and to require less LO power than Nb based diffusion cooled HEBs, have been fabricated. Preliminary DC tests were performed. The bolometer elements consisted of short (0.1 to 0.3 micron), narrow (0.08 to 0. 15 micron) and thin (11 nm) aluminum wires connected to large contact pads consisting of a novel trilayer Al/Ti/Au. The patterns were defined by electron beam lithography and the metal deposition involved a double angle process, the Aluminum wires being deposited straight on and the pads being deposited at a 45 degree angle without breaking vacuum. The Al/Ti/Au trilayer was developed to provide a way of making contact between the aluminum wire and the gold antenna. The Titanium layer acts as a diffusion barrier to avoid damage of the Aluminum contact and bolometer wire and to lower the transition temperature of the pads to below that of the bolometer wire. The Au layer avoids the formation of an oxide on the Ti layer and provides good electrical contact to the IF/antenna structure. The resistance of the bolometers as a function of temperature was measured. It is clear that below the transition temperature of the wire (1.8K) but above the transition temperature of the contact pads (0.6K), the proximity effect drives most of the bolometer wire normal, causing a very broad transition. This effect should not affect the performance of the bolometers since they will be operated at a temperature below the TC of the pads. This is evident from the IV characteristics measured at 0.3K. RF characterization tests will begin shortly.

Software For Three-Dimensional Stress And Thermal Analyses

NASA Technical Reports Server (NTRS)

Banerjee, P. K.; Wilson, R. B.; Hopkins, D. A.

1994-01-01

BEST3D is advanced engineering software system for three-dimensional thermal and stress analyses, particularly of components of hot sections of gas-turbine engines. Utilizes boundary element method, offering, in many situations, more accuracy, efficiency, and ease of use than finite element method. Performs engineering analyses of following types: elastic, heat transfer, plastic, forced vibration, free vibration, and transient elastodynamic. Written in FORTRAN 77.

Turbulence Measurements on a Flap-Edge Model

NASA Technical Reports Server (NTRS)

Moriarty, Patrick; Bradshaw, Peter; Cantwell, Brian; Ross, James

1998-01-01

Turbulence measurements have been made on a flap-edge and leading-edge slat model using hot-wire anemometry, and, later, particle image velocimetry. The properties of hot-wire anemometry were studied using facilities at NASA Ames Research Center. Hot-film probes were used because of their durability, but cross-films were limited by non-linear end effects. As a warm-up exercise, hot-film probes were used to measure velocities in the farfield wake of a cylinder with an airfoil in the near-field wake. The airfoil reduced the drag coefficient of the system by 10%. A single-wire hot-film probe was used to measure velocity profiles over the top of a NACA 63(sub 2)-215 Mod. B wing with a Fowler flap and leading,-edge slat. Results showed the size of slat wake was dependent upon the slat deflection angle. Velocity increased through the slat gap with increased deflection. The acoustically modified slat decreased the chance of separation. Measurements were taken at the flap edge with a single hot-film. Trends in the data indicate velocity and turbulence levels increase at the flap edge. The acoustically modified flap modifies the mean flow near the flap edge. Correlations were made between the hot-film signal and the unsteady pressure transducers on the wing which were published in a NASA CDTM. The principles of Particle Image Velocimetry (PIV) were studied at Florida State University. Spectral PIV was used to measure the spectra of a subsonic jet. Measured frequencies were close to the predicted frequency of jet shedding. Spectral PIV will be used to measure the spectra of the slat flow in the second 7 x lO-ft. wind tunnel test. PIV has an advantage that it can measure velocity and spectra of the entire flowfield instantaneously. However, problems arise when trying, to store this massive amount of PIV data. Support for this research has continued through a NASA Graduate Student Program Fellowship which will end in June 1999. The thesis should be completed by this time.

Experimental study of the transient hydrogen jet - Using a fast response probe

NASA Astrophysics Data System (ADS)

Tanabe, H.; Ohnishi, M.; Sato, G. T.; Fujimoto, H.

Mixing processes of a transient hydrogen jet, such as those of a hydrogen-injection internal combustion engine, are studied by means of a concentration probe having a response time of less than 200 microsec. Hydrogen was injected into quiescent air by means of (1) a single-shot device, in order to study the air interactions of the jet with schlieren photography and smoke wire methods, and (2) a hydrogen diesel engine injection nozzle to determine jet shape with high speed schlieren photography. The concentration probe's response time was found to be adequate for the very short injection period, and it was determined that air-hydrogen mixing in the case of high jet momentum is governed by eddy diffusion.

Hot tube method for the measuring of thermophysical properties of materials

NASA Astrophysics Data System (ADS)

Dieška, Peter; Boháč, Vlastimil; Vretenár, Viliam

2017-07-01

The measurement of thermal properties of materials that do not keep the form is problematic, because usually, the basic condition of the most models predicts constant dimensions. The plastic materials like clay or loam in natural condition always contain some water and thus are viscous and squeeze out of specimen holder when clamped even at weak force produced by specimen holder. Thus, the specimen dimensions are changing in during the measurement when it is not placed in a solid container. Even at this arrangement the shrinkage of material at the measurements causes the lowering the specimen thickness when using two probe method like pulse transient technique. This effect problem could be lowered or neglected at single probe techniques like the planar hot disk or this newly derived hot tube method. Hot tube method is derived for the probe made as the rectangular plane bended around the solid cylinder or tube made of thermally low conducting material. The probe generates the heat and the rate of temperature rise in it is driven by heat transfer ability of the measured surrounding material. Such a probe should be used in laboratory as well as in the field conditions.

FIRE_MS_UKMO_C130

Atmospheric Science Data Center

2015-11-25

... Hot-Wire MCRW Refractometer Platinum Resistance Pressure Transducer RT-4 Pyranometer Pyrgeometer Radiometer Wind ... Parameters:  Dew/Frost Point Temperature Liquid Water Content Humidity Temperature Pressure Irradiance ...

Addressing Machining Issues for the Intermetallic Compound 60-NITINOL

NASA Technical Reports Server (NTRS)

Stanford, Malcolm K.; Wozniak, Walter A.; McCue, Terry R.

2012-01-01

60-NITINOL (60 wt.% Ni - 40 wt.% Ti) is being studied as a material for advanced aerospace components. Frequent wire breakage during electrical-discharge machining of this material was investigated. The studied material was fabricated from hot isostatically pressed 60-NITINOL powder obtained through a commercial source. Bulk chemical analysis of the material showed that the composition was nominal but had relatively high levels of certain impurities, including Al and O. It was later determined that Al2O3 particles had contaminated the material during the hot isostatic pressing procedure and that these particles were the most likely cause of the wire breakage. The results of this investigation highlight the importance of material cleanliness to its further implementation.

Development of Turbulence-Measuring Equipment

NASA Technical Reports Server (NTRS)

Kovasznay, Leslie S G

1954-01-01

Hot wire turbulence-measuring equipment has been developed to meet the more stringent requirements involved in the measurement of fluctuations in flow parameters at supersonic velocities. The higher mean speed necessitates the resolution of higher frequency components than at low speed, and the relatively low turbulence level present at supersonic speed makes necessary an improved noise level for the equipment. The equipment covers the frequency range from 2 to about 70,000 cycles per second. Constant-current operation is employed. Compensation for hot-wire lag is adjusted manually using square-wave testing to indicate proper setting. These and other features make the equipment adaptable to all-purpose turbulence work with improved utility and accuracy over that of older types of equipment. Sample measurements are given to demonstrate the performance.

FIRE_AX_UW_C131A

Atmospheric Science Data Center

2015-11-25

... Hot-Wire Hygrometer RMS Pressure Var Platinum Resistance Pyranometer Radiometer Reverse Flow Spatial ... Parameters:  Condensation Nuclei Dew/Frost Point Temperature Droplet Concentration Humidity Irradiance Liquid Water ...

A Study of Supersonic Compression-Corner Interactions using Hybrid LES/RANS Models

DTIC Science & Technology

2014-01-20

Mach 2.5 shock / boundary layer interaction in a wind tunnel (experiments conducted at Cambridge University [15]) as a means of assessing methods... wind tunnel . The shock impinges upon the bottom surface of the wind tunnel , creating a region of shock -separated flow. The structure of the SBLI... waves into a shock wave (Figure 19, X = 0.1016 and X = 0.1278 stations) are also not well-predicted. The hot-wire measurements may not be as

Visualization of interaction of Mach waves with a bow shock

NASA Astrophysics Data System (ADS)

Pavlov, Al.; Golubev, M.; Kosinov, A.; Pavlov, A.

2017-10-01

The work presents results of investigation of couple weak waves with a bow shock at Mach number M = 2. The waves produced by a small 2D roughness installed on the nozzle inset or side wall of working section. Hot-wire measurements revealed profile of the waves to be similar to N-wave. The visualization was done by means of schlieren technique and interferential AVT SA method. The inclination angle change of the Mach waves at free-stream section and bow shock section was found.

Avionics electromagnetic interference immunity and environment

NASA Technical Reports Server (NTRS)

Clarke, C. A.

1986-01-01

Aircraft electromagnetic spectrum and radio frequency (RF) field strengths are charted, profiling the higher levels of electromagnetic voltages encountered by the commercial aircraft wiring. Selected military, urban, and rural electromagnetic field levels are plotted and provide a comparison of radiation amplitudes. Low frequency magnetic fields and electric fields from 400 H(Z) power systems are charted versus frequency and wire separation to indicate induced voltages on adjacent or neighboring circuits. Induced EMI levels and attenuation characteristics of electric, magnetic, RF fields, and transients are plotted and graphed for common types of wire circuits. The significance of wire circuit returns and shielding is emphasized to highlight the techniques that help block the paths of electromagnetic interference and maintain avionic interface signal quality.

Test methods and response surface models for hot, humid air decontamination of materials contaminated with dirty spores of Bacillus anthracis ∆Sterne and Bacillus thuringiensis Al Hakam.

PubMed

Buhr, T L; Young, A A; Barnette, H K; Minter, Z A; Kennihan, N L; Johnson, C A; Bohmke, M D; DePaola, M; Cora-Laó, M; Page, M A

2015-11-01

To develop test methods and evaluate survival of Bacillus anthracis ∆Sterne or Bacillus thuringiensis Al Hakam on materials contaminated with dirty spore preparations after exposure to hot, humid air using response surface modelling. Spores (>7 log10 ) were mixed with humic acid + spent sporulation medium (organic debris) or kaolin (dirt debris). Spore samples were then dried on five different test materials (wiring insulation, aircraft performance coating, anti-skid, polypropylene, and nylon). Inoculated materials were tested with 19 test combinations of temperature (55, 65, 75°C), relative humidity (70, 80, 90%) and time (1, 2, 3 days). The slowest spore inactivation kinetics was on nylon webbing and/or after addition of organic debris. Hot, humid air effectively decontaminates materials contaminated with dirty Bacillus spore preparations; debris and material interactions create complex decontamination kinetic patterns; and B. thuringiensis Al Hakam is a realistic surrogate for B. anthracis. Response surface models of hot, humid air decontamination were developed which may be used to select decontamination parameters for contamination scenarios including aircraft. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Long-range distributed optical fiber hot-wire anemometer based on chirped-pulse ΦOTDR.

PubMed

Garcia-Ruiz, Andres; Dominguez-Lopez, Alejandro; Pastor-Graells, Juan; Martins, Hugo F; Martin-Lopez, Sonia; Gonzalez-Herraez, Miguel

2018-01-08

We demonstrate a technique allowing to develop a fully distributed optical fiber hot-wire anemometer capable of reaching a wind speed uncertainty of ≈ ±0.15m/s (±0.54km/h) at only 60 mW/m of dissipated power in the sensing fiber, and within only four minutes of measurement time. This corresponds to similar uncertainty values than previous papers on distributed optical fiber anemometry but requires two orders of magnitude smaller dissipated power and covers at least one order of magnitude longer distance. This breakthrough is possible thanks to the extreme temperature sensitivity and single-shot performance of chirped-pulse phase-sensitive optical time domain reflectometry (ΦOTDR), together with the availability of metal-coated fibers. To achieve these results, a modulated current is fed through the metal coating of the fiber, causing a modulated temperature variation of the fiber core due to Joule effect. The amplitude of this temperature modulation is strongly dependent on the wind speed at which the fiber is subject. Continuous monitoring of the temperature modulation along the fiber allows to determine the wind speed with singular low power injection requirements. Moreover, this procedure makes the system immune to temperature drifts of the fiber, potentially allowing for a simple field deployment. Being a much less power-hungry scheme, this method also allows for monitoring over much longer distances, in the orders of 10s of km. We expect that this system can have application in dynamic line rating and lateral wind monitoring in railway catenary wires.

Extended Operation of Stirling Convertors at NASA Glenn Research Center

NASA Technical Reports Server (NTRS)

Oriti, Salvatore

2011-01-01

Glenn Research Center (GRC) is supporting life and reliability database for free-piston Stirilng conversion via extended convertor operation Ongoing convertor operation: 18 convertors (4 TDCs from Infinia, 14 ASCs from Sunpower). 350,000 total convertor hours of operation. 218,000 on Infinia units and 132,000 on Sunpower units. Demonstrating steady convertor performance requires precise maintenance of operating conditions. Sources of disruption : Investigative tests: Varying operating frequency, hot-end temp, cold-end temp. Hot end control method: Constant heat input mode requires more user-adjustment than constant temperature mode. Long-term transients in hot end insulation were observed. Support facility: Open-bath circulator fluid concentration drifting. Nuisance shutdowns (instrumentation failure, EMI, power outages). Ambient temperature fluctuations due to room HVAC.

Transient Heat Transfer in a Semitransparent Radiating Layer with Boundary Convection and Surface Reflections

NASA Technical Reports Server (NTRS)

Siegel, Robert

1996-01-01

Surface convection and refractive index are examined during transient radiative heating or cooling of a grey semitransparent layer with internal absorption, emission and conduction. Each side of the layer is exposed to hot or cold radiative surroundings, while each boundary is heated or cooled by convection. Emission within the layer and internal reflections depend on the layer refractive index. The reflected energy and heat conduction distribute energy across the layer and partially equalize the transient temperature distributions. Solutions are given to demonstrate the effect of radiative heating for layers with various optical thicknesses, the behavior of the layer heated by radiation on one side and convectively cooled on the other, and a layer heated by convection while being cooled by radiation. The numerical method is an implicit finite difference procedure with non-uniform space and time increments. The basic method developed in earlier work is expanded to include external convection and incident radiation.

Measurements of fluctuating gas temperatures using compensated fine wire thermocouples

NASA Astrophysics Data System (ADS)

Nina, M. N. R.; Pita, G. P.

1985-09-01

Thermocouples with three different wire diameters (15, 40 and 50 microns) were used in association with an analog compensation circuit connected to a data acquisition system. Measurements of the time constant were performed using two different heating techniques; Joule effect and external heating by laser beam. The thermocouples were used to quantify the fluctuating temperature field in a hot air jet and in a premixed propane flame. In the reacting case the catalytic effect was evaluated by comparing coated and uncoated wires. Conclusions were also obtained regarding frequency spectra, temperature probability distribution function and time constant.

Investigation of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1985-01-01

Activities undertaken during the entire course of research are summarized. Studies were concerned with experimental and theoretical research on 2-D axisymmetric geometries under low speed nonreacting, turbulent, swirling flow conditions typical of gas turbine and ramjet combustion chambers. They included recirculation zone characterization, time-mean and turbulence simulation in swirling recirculating flow, sudden and gradual expansion flowfields, and furher complexities and parameter influences. The study included the investigation of: a complete range of swirl strengths; swirler performance; downstream contraction nozzle sizes and locations; expansion ratios; and inlet side-wall angles. Their individual and combined effects on the test section flowfield were observed, measured and characterized. Experimental methods included flow visualization (with smoke and neutrally-buoyant helium-filled soap bubbles), five-hole pitot probe time-mean velocity field measurements, and single-, double-, and triple-wire hot-wire anemometry measurements of time-mean velocities, normal and shear Reynolds sresses. Computational methods included development of the STARPIC code from the primitive-variable TEACH computer code, and its use in flowfield prediction and turbulence model development.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Ching-Fong; Pokharel, Reeju; Brand, Michael J.

Here, we developed a copper/tungsten (Cu/W) composite for mesoscale Materials Science applications using the novel High-Energy Diffraction Microscopy (HEDM) technique. Argon-atomized copper powder was selected as the starting raw powder and screened to remove the extremely large particle fraction. Tungsten particles were collected by milling and screening the -325 mesh tungsten powder between 500 and 635 mesh sieves. Hot pressing of screened Cu powder was performed at 900 °C in Ar/4 %H 2 atmosphere. XRD and ICP results show that the hot-pressed Cu sample consists of about 5 vol% Cu 2O, which is caused by the presence of oxygen onmore » the surface of the starting Cu powder. Hot pressing the copper powder in a pure hydrogen atmosphere was successful in removing most of the surface oxygen. Our process was also implemented for hot pressing the Cu/W composite. The density of the Cu/W composites hot pressed at 950 °C in pure hydrogen was about 94 % of the theoretical density (TD). The hot-pressed Cu/W composites were further hot isostatic pressed at 1050 °C in argon atmosphere, which results in 99.6 % of the TD with the designed Cu grain size and W particle distribution. Tensile specimens with D-notch were machined using the wire EDM method. Furthermore, the processing and consolidation of these materials will be discussed in detail. The HEDM images are also showed and discussed.« less

Microstructure and mechanical properties of hot wire laser clad layers for repairing precipitation hardening martensitic stainless steel

NASA Astrophysics Data System (ADS)

Wen, Peng; Cai, Zhipeng; Feng, Zhenhua; Wang, Gang

2015-12-01

Precipitation hardening martensitic stainless steel (PH-MSS) is widely used as load-bearing parts because of its excellent overall properties. It is economical and flexible to repair the failure parts instead of changing new ones. However, it is difficult to keep properties of repaired part as good as those of the substrate. With preheating wire by resistance heat, hot wire laser cladding owns both merits of low heat input and high deposition efficiency, thus is regarded as an advantaged repairing technology for damaged parts of high value. Multi-pass layers were cladded on the surface of FV520B by hot wire laser cladding. The microstructure and mechanical properties were compared and analyzed for the substrate and the clad layer. For the as-cladded layer, microstructure was found non-uniform and divided into quenched and tempered regions. Tensile strength was almost equivalent to that of the substrate, while ductility and impact toughness deteriorated much. With using laser scanning layer by layer during laser cladding, microstructure of the clad layers was tempered to fine martensite uniformly. The ductility and toughness of the clad layer were improved to be equivalent to those of the substrate, while the tensile strength was a little lower than that of the substrate. By adding TiC nanoparticles as well as laser scanning, the precipitation strengthening effect was improved and the structure was refined in the clad layer. The strength, ductility and toughness were all improved further. Finally, high quality clad layers were obtained with equivalent or even superior mechanical properties to the substrate, offering a valuable technique to repair PH-MSS.

A high speed data acquisition and analysis system for transonic velocity, density, and total temperature fluctuations

NASA Technical Reports Server (NTRS)

Clukey, Steven J.

1988-01-01

The high speed Dynamic Data Acquisition System (DDAS) is described which provides the capability for the simultaneous measurement of velocity, density, and total temperature fluctuations. The system of hardware and software is described in context of the wind tunnel environment. The DDAS replaces both a recording mechanism and a separate data processing system. The data acquisition and data reduction process has been combined within DDAS. DDAS receives input from hot wires and anemometers, amplifies and filters the signals with computer controlled modules, and converts the analog signals to digital with real-time simultaneous digitization followed by digital recording on disk or tape. Automatic acquisition (either from a computer link to an existing wind tunnel acquisition system, or from data acquisition facilities within DDAS) collects necessary calibration and environment data. The generation of hot wire sensitivities is done in DDAS, as is the application of sensitivities to the hot wire data to generate turbulence quantities. The presentation of the raw and processed data, in terms of root mean square values of velocity, density and temperature, and the processing of the spectral data is accomplished on demand in near-real-time- with DDAS. A comprehensive description of the interface to the DDAS and of the internal mechanisms will be prosented. A summary of operations relevant to the use of the DDAS will be provided.

FIRE_CI2_CITATN_1HZ

Atmospheric Science Data Center

2015-11-25

... Flow Angle Sensors Hot-Wire Icing Rate Detector Pressure Transducer Reverse Flow Temperature Probes Spatial ... Condensation Nuclei Dew/Frost Point Temperature Liquid Water Content Nitrogen Dioxide Ozone Pressure Supercooled ...

Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots

PubMed Central

Busch, Martin HJ; Vollmann, Wolfgang; Grönemeyer, Dietrich HW

2006-01-01

Background Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example). The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach ¼ of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to. Methods First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging investigations. The finite volume analysis calculates the time developing temperature maps for the model of a broken linear metallic wire embedded in tissue. Half of the total hot spot power loss is assumed to diffuse into both wire parts at the location of a defect. The energy is distributed from there by heat conduction. Additionally the effect of blood perfusion and blood flow is respected in some simulations because the simultaneous appearance of all worst case conditions, especially the absence of blood perfusion and blood flow near the hot spot, is very unlikely for vessel implants. Results The analytical solution as worst case scenario as well as the finite volume analysis for near worst case situations show not negligible volumes with critical temperature increases for part of the modeled hot spot situations. MR investigations with a high rf-pulse density lasting below a minute can establish volumes of several cubic millimeters with temperature increases high enough to start cell destruction. Longer exposure times can involve volumes larger than 100 mm3. Even temperature increases in the range of thermal ablation are reached for substantial volumes. MR sequence exposure time and hot spot power loss are the primary factors influencing the volume with critical temperature increases. Wire radius, wire material as well as the physiological parameters blood perfusion and blood flow inside larger vessels reduce the volume with critical temperature increases, but do not exclude a volume with critical tissue heating for resonators with a large product of resonator volume and quality factor. Conclusion The worst case scenario assumes thermal equilibrium for a hot spot embedded in homogeneous tissue without any cooling due to blood perfusion or flow. The finite volume analysis can calculate the results for near and not close to worst case conditions. For both cases a substantial volume can reach a critical temperature increase in a short time. The analytical solution, as absolute worst case, points out that resonators with a small product of inductance volume and quality factor (Q Vind < 2 cm3) are definitely save. Stents for coronary vessels or resonators used as tracking devices for interventional procedures therefore have no risk of high temperature increases. The finite volume analysis shows for sure that also conditions not close to the worst case reach physiologically critical temperature increases for implants with a large product of inductance volume and quality factor (Q Vind > 10 cm3). Such resonators exclude patients from exactly the MRI investigation these devices are made for. PMID:16729878

Method for rapid, controllable growth and thickness, of epitaxial silicon films

DOEpatents

Wang, Qi [Littleton, CO; Stradins, Paul [Golden, CO; Teplin, Charles [Boulder, CO; Branz, Howard M [Boulder, CO

2009-10-13

A method of producing epitaxial silicon films on a c-Si wafer substrate using hot wire chemical vapor deposition by controlling the rate of silicon deposition in a temperature range that spans the transition from a monohydride to a hydrogen free silicon surface in a vacuum, to obtain phase-pure epitaxial silicon film of increased thickness is disclosed. The method includes placing a c-Si substrate in a HWCVD reactor chamber. The method also includes supplying a gas containing silicon at a sufficient rate into the reaction chamber to interact with the substrate to deposit a layer containing silicon thereon at a predefined growth rate to obtain phase-pure epitaxial silicon film of increased thickness.

The Effect of Annealing on the Elastic Modulus of Orthodontic Wires

NASA Astrophysics Data System (ADS)

Higginbottom, Kyle

Introduction: Nickel Titanium orthodontic wires are currently used in orthodontic treatment due to their heat activated properties and their delivery of constant force. The objective of this study was to determine the effect of annealing on the elastic modulus of Nickel Titanium, Stainless Steel and Beta-titanium (TMA) wires. Different points along the wire were tested in order to determine how far from the annealed ends the elastic modulus of the wires was affected. Methods: Eighty (80) orthodontic wires consisting of 4 equal groups (SS/TMA/Classic NitinolRTM/Super Elastic NitinolRTM) were used as the specimens for this study. All wires were measured and marked at 5mm measurements, and cut into 33.00mm sections. The wires were heated with a butane torch until the first 13.00mm of the wires were red hot. Load deflection tests using an InstronRTM universal testing machine were run at 5mm distances from the end of the wire that had been annealed. The change in elastic modulus was then determined. Results: There was a significant difference (F = 533.001, p = 0.0005) in the change in elastic modulus for the four distances. There was also a significant difference (F = 57.571, p = 0.0005) in the change in elastic modulus for the four wire types. There was a significant interaction (F = 19.601, p = 0.005) between wire type and distance, however this interaction negated the differences between the wires. Conclusion: 1) There are significant differences in the changes in elastic modulus between the areas of the wires within the annealed section and those areas 5mm and 10mm away from the annealed section. The change in elastic modulus within the annealed section was significantly greater at 8 mm than it was at 13mm, and this was significantly greater than 18mm and 23mm (5mm and 10mm beyond the annealed section). However, there was no statistical difference in the change in elastic modulus between 5mm and 10mm away from the annealed section (18mm and 23mm respectively). 2) Regardless of the wire type, no clinically important effects were seen 5mm and 10mm beyond the annealed portion.

Development of an instantaneous local fuel-concentration measurement probe: an engine application

NASA Astrophysics Data System (ADS)

Guibert, P.; Boutar, Z.; Lemoyne, L.

2003-11-01

This work presents a new tool which can deliver instantaneous local measurements of fuel concentration in an engine cylinder with a high temporal resolution, particularly during compression strokes. Fuel concentration is represented by means of equivalence fuel-air ratio, i.e. the real engine mass ratio of fuel to air divided by the same ratio in ideal stoichiometry conditions. Controlling the mixture configuration for any strategy in a spark ignition engine and for auto-ignition combustion has a dominant effect on the subsequent processes of ignition, flame propagation and auto-ignition combustion progression, pollutant formation under lean or even stoichiometric operating conditions. It is extremely difficult, under a transient operation, to control the equivalence air/fuel ratio precisely at a required value and at the right time. This requires the development of a highly accurate equivalence air/fuel ratio control system and a tool to measure using crank angle (CA) resolution. Although non-intrusive laser techniques have considerable advantages, they are most of the time inappropriate due to their optical inaccessibility or the complex experimental set-up involved. Therefore, as a response to the demand for a relatively simple fuel-concentration measurement system a probe is presented that replaces a spark plug and allows the engine to run completely normally. The probe is based on hot-wire like apparatus, but involves catalytic oxidation at the wire surface. The development, characteristics and calibration of the probe are presented followed by applications to in-cylinder engine measurements.

Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading.

PubMed

Barth, C; Seeber, B; Rack, A; Calzolaio, C; Zhai, Y; Matera, D; Senatore, C

2018-04-26

Understanding the critical current performance variation of Nb 3 Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation between the void morphology and the electro-mechanical limits measured on different Bronze route Nb 3 Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires' void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Finally, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation upon mechanical loading.

Femtosecond transient absorption dynamics of close-packed gold nanocrystal monolayer arrays*1

NASA Astrophysics Data System (ADS)

Eah, Sang-Kee; Jaeger, Heinrich M.; Scherer, Norbert F.; Lin, Xiao-Min; Wiederrecht, Gary P.

2004-03-01

Femtosecond transient absorption spectroscopy is used to investigate hot electron dynamics of close-packed 6 nm gold nanocrystal monolayers. Morphology changes of the monolayer caused by the laser pump pulse are monitored by transmission electron microscopy. At low pump power, the monolayer maintains its structural integrity. Hot electrons induced by the pump pulse decay through electron-phonon (e-ph) coupling inside the nanocrystals with a decay constant that is similar to the value for bulk films. At high pump power, irreversible particle aggregation and sintering occur in the nanocrystal monolayer, which cause damping and peak shifting of the transient bleach signal.

Occipitocervical fusions in children. Retrospective analysis and technical considerations.

PubMed

Rodgers, W B; Coran, D L; Emans, J B; Hresko, M T; Hall, J E

1999-07-01

This report presents a retrospective analysis of the authors' experience with occipitocervical fusions in children and adolescents during the last 2 decades. A description of an operative technique devised by the senior author (JEH), and a comparison of the results using this and other methods of fusion are given. Twenty-three patients underwent occipitocervical fusion. Fifteen of the patients were operated on using the authors' technique. To achieve stable fixation of the distal cervical vertebra a threaded Kirschner wire was passed transversely through the spinous process; occipital fixation was achieved by the traditional method of wiring corticocancellous bone graft to the skull through burr holes. The occipital wires then were wrapped around the Kirschner wire and the graft was cradled in the resulting nest. Halo immobilization was used in 10 patients for an average of 12.5 weeks (range, 6-24 weeks). Twenty-two patients achieved successful fusion at an average followup of 5.8 years (range, 1-14.33 years). Several complications, including transient quadriplegia in one patient, pseudarthrosis in two (one of which persists), hardware fixation failure in one, unintended distal extension of the fusion, pneumonia, wound infection, halo pin infection, skin breakdown under the halo vest, hydrocephalus, cerebrospinal fluid leak, and traumatic fusion fracture were encountered. Results using the technique described herein are comparable with or better than the results reported in the previous literature, and the results of the patients in this series in whom the technique was not used.

FIRE_AX_UKMO_C130

Atmospheric Science Data Center

2015-11-25

... FSSP Gust Probe Hot-Wire Hygrometer Platinum Resistance PMS 2D-C Probe PRT-4 Pyranometer Pyrgeometer ... Parameters:  Barometric Altitude Cloud Top Temperature Deiced Temperature Dew/Frost Point Temperature Droplet ...

Across-shift changes in the pulmonary function of meat-wrappers and other workers in the retail food industry.

PubMed

Eisen, E A; Wegman, D H; Smith, T J

1985-02-01

Pulmonary function was measured before, during, and after the end of the workshift in 83 workers in the retail food industry. All acute changes in forced expiratory volume in 1 s were standardized for lung size before the magnitude of the changes were compared between the workers exposed and unexposed to the use of hot wires for cutting plastic film. No association was found between acute drop in pulmonary function and either direct or indirect exposure in the absence of a history of asthma or allergy to inhaled materials. The borderline significance of an interaction term between exposure and asthma/allergy in a regression analysis suggests that workers with a history of asthma or atopy may have an acute response to hot-wire wrapping emissions.

An experimental investigation of bending wave instability modes in a generic four-vortex wake

DOE Office of Scientific and Technical Information (OSTI.GOV)

Babie, Brian M.; Nelson, Robert C.

2010-07-15

An experimental study of a planar wake consisting of four vortices that simulate the trailing vortex wakes generated by transport airplanes in either takeoff or landing configurations is presented. The objective of this study was to examine naturally occurring wake instabilities. Specifically, the focus of the study was centered on bending wave instabilities of which the Crow instability represents a particular case. A unique method of generating a four-vortex wake was developed for this study. The four-vortex wake generating device permitted direct variation of the spacing between vortices as well as control over the vortex circulation strength. Two quantitative flowmore » visualization experiments were instrumental in identifying wake configurations that were conducive to the rapid growth of bending wave modes and in the identification of the long-wavelength mode. Detailed experiments were also conducted to examine the flow structure in the near-field or roll-up region using a four sensor, hot-wire probe that could measure all three velocity components in the wake simultaneously. The results of both the flow visualization and hot-wire experiments indicate that the long-wavelength mode and the first short-wavelength mode likely dominate the far-field wake physics and may potentially be utilized in a wake control strategy.« less

Turbulence measurements in hypersonic boundary layers using constant-temperature anemometry and Reynolds stress measurements in hypersonic boundary layers

NASA Technical Reports Server (NTRS)

Spina, Eric F.

1995-01-01

The primary objective in the two research investigations performed under NASA Langley sponsorship (Turbulence measurements in hypersonic boundary layers using constant temperature anemometry and Reynolds stress measurements in hypersonic boundary layers) has been to increase the understanding of the physics of hypersonic turbulent boundary layers. The study began with an extension of constant-temperature thermal anemometry techniques to a Mach 11 helium flow, including careful examinations of hot-wire construction techniques, system response, and system calibration. This was followed by the application of these techniques to the exploration of a Mach 11 helium turbulent boundary layer (To approximately 290 K). The data that was acquired over the course of more than two years consists of instantaneous streamwise mass flux measurements at a frequency response of about 500 kHz. The data are of exceptional quality in both the time and frequency domain and possess a high degree of repeatability. The data analysis that has been performed to date has added significantly to the body of knowledge on hypersonic turbulence, and the data reduction is continuing. An attempt was then made to extend these thermal anemometry techniques to higher enthalpy flows, starting with a Mach 6 air flow with a stagnation temperature just above that needed to prevent liquefaction (To approximately 475 F). Conventional hot-wire anemometry proved to be inadequate for the selected high-temperature, high dynamic pressure flow, with frequent wire breakage and poor system frequency response. The use of hot-film anemometry has since been investigated for these higher-enthalpy, severe environment flows. The difficulty with using hot-film probes for dynamic (turbulence) measurements is associated with construction limitations and conduction of heat into the film substrate. Work continues under a NASA GSRP grant on the development of a hot film probe that overcomes these shortcomings for hypersonic flows. Each of the research tasks performed during the NASA Langley research grants is discussed separately below.

An experimental study of the vortex wake at Mach number of 3

NASA Astrophysics Data System (ADS)

Shmakov, A. S.; Shevchenko, A. M.

2017-10-01

The results of experimental study of the flow in the wing wake at Mach number of 3 are presented. These experiments extends the data obtained in the same experimental setup at Mach numbers of 2.5 and 4 [1]. Experiments were carried out in supersonic wind tunnel T-325 of ITAM SB RAS. Rectangular half-wing with sharp edges with a chord length of 30 mm and semispan of 95 mm was used to generate vortex wake. Experimental data were obtained in two cross sections located 1.5 and 6 chord length downstream of the trailing edge at wing angle of attack of 10 degrees. Constant temperature hot-wire anemometer was used to measure disturbances in supersonic flow. Hot-wire aemometer was made of a tungsten wire with a diameter of 10 µm and length of 1.5 mm. Shlieren flow visualization were performed. As a result, the position and size of the vortex core in the wake of a rectangular wing were determined. For the first time mass flow distribution and its pulsations in the supersonic longitudinal vortex was measured at Mach number of 3.

LENR BEC Clusters on and below Wires through Cavitation and Related Techniques

NASA Astrophysics Data System (ADS)

Stringham, Roger; Stringham, Julie

2011-03-01

During the last two years I have been working on BEC cluster densities deposited just under the surface of wires, using cavitation, and other techniques. If I get the concentration high enough before the clusters dissipate, in addition to cold fusion related excess heat (and other effects, including helium-4 formation) I anticipate that it may be possible to initiate transient forms of superconductivity at room temperature.

Reusable Hot-Wire Cable Cutter

NASA Technical Reports Server (NTRS)

Pauken, Michael T.; Steinkraus, Joel M.

2010-01-01

During the early development stage of balloon deployment systems for missions, nichrome wire cable cutters were often used in place of pyro-actuated cutters. Typically, a nichrome wire is wrapped around a bundle of polymer cables with a low melting point and connected to a relay-actuated electric circuit. The heat from the nichrome reduces the strength of the cable bundle, which quickly breaks under a mechanical load and can thus be used as a release mechanism for a deployment system. However, the use of hand-made heated nichrome wire for cutters is not very reliable. Often, the wrapped nichrome wire does not cut through the cable because it either pulls away from its power source or does not stay in contact with the cable being cut. Because nichrome is not readily soldered to copper wire, unreliable mechanical crimps are often made to connect the nichrome to an electric circuit. A self-contained device that is reusable and reliable was developed to sever cables for device release or deployment. The nichrome wire in this new device is housed within an enclosure to prevent it from being damaged by handling. The electric power leads are internally connected within the unit to the nichrome wire using a screw terminal connection. A bayonet plug, a quick and secure method of connecting the cutter to the power source, is used to connect the cutter to the power leads similar to those used in pyro-cutter devices. A small ceramic tube [0.25-in. wide 0.5-in. long (.6.4-mm wide 13-mm long)] houses a spiraled nichrome wire that is heated when a cable release action is required. The wire is formed into a spiral coil by wrapping it around a mandrel. It is then laid inside the ceramic tube so that it fits closely to the inner surface of the tube. The ceramic tube provides some thermal and electrical insulation so that most of the heat generated by the wire is directed toward the cable bundle in the center of the spiral. The ceramic tube is cemented into an aluminum block, which holds it in position. The leads of the nichrome wire are attached to screw terminals that connect them to power leads. A bayonet plug mounted at the bottom of the rectangular block connects the power leads to a relay circuit. A thin aluminum shell encloses the entire structure, leaving access points to attach to the bayonet plug and to feed a cable into the cylinder. The access holes for the deployment cable are a smaller diameter than the nichrome coil to prevent the cable from coming in direct contact with the nichrome when loaded. It uses the same general method of severing a cable with a heated wire as was used previously, but implements it in such a way that it is more reliable and less prone to failure. It creates a mechanism to create repeatability that was nonexistent in the previous method.

Frequency and time domain three-dimensional inversion of electromagnetic data for a grounded-wire source

NASA Astrophysics Data System (ADS)

Sasaki, Yutaka; Yi, Myeong-Jong; Choi, Jihyang; Son, Jeong-Sul

2015-01-01

We present frequency- and time-domain three-dimensional (3-D) inversion approaches that can be applied to transient electromagnetic (TEM) data from a grounded-wire source using a PC. In the direct time-domain approach, the forward solution and sensitivity were obtained in the frequency domain using a finite-difference technique, and the frequency response was then Fourier-transformed using a digital filter technique. In the frequency-domain approach, TEM data were Fourier-transformed using a smooth-spectrum inversion method, and the recovered frequency response was then inverted. The synthetic examples show that for the time derivative of magnetic field, frequency-domain inversion of TEM data performs almost as well as time-domain inversion, with a significant reduction in computational time. In our synthetic studies, we also compared the resolution capabilities of the ground and airborne TEM and controlled-source audio-frequency magnetotelluric (CSAMT) data resulting from a common grounded wire. An airborne TEM survey at 200-m elevation achieved a resolution for buried conductors almost comparable to that of the ground TEM method. It is also shown that the inversion of CSAMT data was able to detect a 3-D resistivity structure better than the TEM inversion, suggesting an advantage of electric-field measurements over magnetic-field-only measurements.

Hot Films on Ceramic Substrates for Measuring Skin Friction

NASA Technical Reports Server (NTRS)

Noffz, Greg; Leiser, Daniel; Bartlett, Jim; Lavine, Adrienne

2003-01-01

Hot-film sensors, consisting of a metallic film on an electrically nonconductive substrate, have been used to measure skin friction as far back as 1931. A hot film is maintained at an elevated temperature relative to the local flow by passing an electrical current through it. The power required to maintain the specified temperature depends on the rate at which heat is transferred to the flow. The heat transfer rate correlates to the velocity gradient at the surface, and hence, with skin friction. The hot-film skin friction measurement method is most thoroughly developed for steady-state conditions, but additional issues arise under transient conditions. Fabricating hot-film substrates using low-thermal-conductivity ceramics can offer advantages over traditional quartz or polyester-film substrates. First, a low conductivity substrate increases the fraction of heat convected away by the fluid, thus increasing sensitivity to changes in flow conditions. Furthermore, the two-part, composite nature of the substrate allows the installation of thermocouple junctions just below the hot film, which can provide an estimate of the conduction heat loss.

Fire Signatures of Materials Used in Spacecraft Construction

NASA Technical Reports Server (NTRS)

Taylor, Christina

2003-01-01

The focus of my work this summer was fire safety, specifically determining fire signatures from the combustion of materials commonly found in the construction of spacecraft. This project was undertaken with the aim of addressing concerns for health and safety onboard spacecraft. Under certain conditions, burning electronics produce surprisingly large amounts of acrid smoke, release fine airborne particles and expel condensable aerosols. Similarly, some wire insulation and packing material evolves smoke when in contact with a hot surface. In the limited, enclosed space available on spacecraft, these combustion products may pose a nuisance at the very least - at worst, a hazard to health or equipment. There is also a concern for fire safety in early detection on spacecraft. Our goal for the summer was to determine the most effective methods to test the materials, develop a protocol for sampling, and generate samples for analysis. We restricted our testing to electronic components, packaging and insulation materials, and wire insulation materials.

System for phase-contrast x-ray radiography using X pinch radiation and a method thereof

DOEpatents

Chandler, Katherine; Chelkovenko, Tatiana; Hammer, David; Pikuz, Sergei; Sinars, Daniel; Song, Byungmoo

2007-11-06

A radiograph system with an anode plate, a cathode plate, and a power source coupled to said anode plate and the cathode plate. At least two wires coupled between the anode plate and the cathode plate provide a configuration to form an X-pinch having a photon source size of less than five microns at energies above 2.5 keV. Material at the configuration forming the X-pinch vaporizes upon application of a suitable current to the wires forming a dense hot plasma and emitting a single x-ray pulse with sufficient photons having energies in the range of from about 2.5 keV to about 20 keV to provide a phase contrast image of an object in the path of the photons. Multiple simultaneous images may be formed of a plurality of objects. Suitable filters and x-ray detectors are provided.

Heat transfer from cylinders in subsonic slip flows

NASA Technical Reports Server (NTRS)

Nagabushana, K. A.; Stainback, P. C.

1992-01-01

The heat transfer in heated wires was measured using a constant temperature anemometer over a Mach number range from 0.05 to 0.4 and pressures from 0.5 to 8.0 atmospheres. The total temperature ranged from 80 to 120 F and the wire diameters were 0.00015, 0.00032, and 0.00050 inch. The heat transfer data is presented in the form of a corrected Nusselt number. Based on suggested criteria, much of the data was obtained in the slip flow regime. Therefore, the data is compared with data having comparable flow conditions. The possible application of the heat transfer data to hot wire anemometry is discussed. To this end, the sensitivity of the wires to velocity, density, and total temperature is computed and compared using two different types of correlations.

FIRE_CI1_KINGAIR

Atmospheric Science Data Center

2016-01-27

... Probe Hot-Wire Hygrometer Photometer Platinium Resistance PMS 2D-C Probe PMS 2D-P Probe PRT-5 Pyranometer ... Ice Irradiance Liquid Water Content Mixing Ratio Temperature Wind Direction Wind Speed Order Data:  ...

FIRE_CI2_KINGAIR

Atmospheric Science Data Center

2015-11-25

... Probe Hot-Wire Hygrometer Photometer Platinum Resistance PMS 2D-C Probe PMS 2D-P Probe PRT-5 Pyranometer ... Ice Irradiance Liquid Water Content Mixing Ratio Temperature Wind Direction Wind Speed Order Data:  ...

40 CFR 420.124 - New source performance standards (NSPS).

Code of Federal Regulations, 2010 CFR

2010-07-01

... GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating Subcategory § 420.124...) Wire products and fasteners. Subpart L Pollutant or pollutant property New source performance standards...

40 CFR 420.124 - New source performance standards (NSPS).

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating Subcategory § 420.124...) Wire products and fasteners. Subpart L Pollutant or pollutant property New source performance standards...

40 CFR 420.126 - Pretreatment standards for new sources (PSNS).

Code of Federal Regulations, 2010 CFR

2010-07-01

...) EFFLUENT GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating... rinse step. (2) [Reserved] (b) Galvanizing and other coatings—(1) Wire products and fasteners. Subpart L...

n-Type diamond and method for producing same

DOEpatents

Anderson, Richard J.

2002-01-01

A new n-type semiconducting diamond is disclosed, which is doped with n-type dopant atoms. Such diamond is advantageously formed by chemical vapor deposition from a source gas mixture comprising a carbon source compound for the diamond, and a volatile hot wire filament for the n-type impurity species, so that the n-type impurity atoms are doped in the diamond during its formation. A corresponding chemical vapor deposition method of forming the n-type semiconducting diamond is disclosed. The n-type semiconducting diamond of the invention may be usefully employed in the formation of diamond-based transistor devices comprising pn diamond junctions, and in other microelectronic device applications.

Transverse vorticity measurements using an array of four hot-wire probes

NASA Technical Reports Server (NTRS)

Foss, J. F.; Klewickc, C. L.; Disimile, P. J.

1986-01-01

A comprehensive description of the technique used to obtain a time series of the quasi-instantaneous transverse vorticity from a four wire array of probes is presented. The algorithmic structure which supports the technique is described in detail and demonstration data, from a large plane shear layer, are presented to provide a specific utilization of the technique. Sensitivity calculations are provided which allow one contribution to the inherent uncertainty of the technique to be evaluated.

40 CFR 420.125 - Pretreatment standards for existing sources (PSES).

Code of Federal Regulations, 2010 CFR

2010-07-01

... (CONTINUED) EFFLUENT GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating... wastewaters from the chromate rinse step. (2) [Reserved] (b) Galvanizing and other coatings—(1) Wire products...

Safety for Older Consumers: Home Safety Checklist

MedlinePlus

... 3 Keep ashtrays, smoking materi- als, candles, hot plates and other potential fire sources away from curtains, ... A ll electrical outlets and switches have cover plates installed so no wiring is exposed. U nused ...

Investigation of Point Doppler Velocimetry (PDV) for Transition Detection in Boundary Layers

NASA Technical Reports Server (NTRS)

Kuhlman, John M.

1999-01-01

A two component Point Doppler Velocimetry (PDV) system has been developed and tested. Improvements were made to an earlier PDV system, in terms of experimental techniques, as well as the data acquisition and reduction software. Measurements of the streamwise and spanwise mean and fluctuating velocities for flows from a rectangular channel and over an NACA 0012 airfoil were made, and the data were compared against hot wire data. The closest to the airfoil surface that PDV measurements could be made was on the order of 0.005 m(0.2", z/c = 0.0169). When the PDV and hot wire data were compared, the time traces for each appeared similar. The mean velocities agreed to within plus or minus 2 m/sec, while the RMS velocities agreed to plus or minus 0.4 m/sec. While the PDV time autocorrelations agreed with those of the hot wire data, the PDV power spectral densities were noisier above 750 Hz. A major source of error in these experiments was determined to be the drifting of the iodine cell stem temperatures. While the stem temperatures were controlled to within plus or minus 0.1 C, this could lead to a frequency shift of as much as 6 MHz, which translates into an error of 1.6 m/sec for the back scatter channel, and up to 6.9 m/sec for the forward scatter channel. These error estimates are consistent with the observed error magnitudes.

Processing and consolidation of copper/tungsten

DOE PAGES

Chen, Ching-Fong; Pokharel, Reeju; Brand, Michael J.; ...

2016-09-27

Here, we developed a copper/tungsten (Cu/W) composite for mesoscale Materials Science applications using the novel High-Energy Diffraction Microscopy (HEDM) technique. Argon-atomized copper powder was selected as the starting raw powder and screened to remove the extremely large particle fraction. Tungsten particles were collected by milling and screening the -325 mesh tungsten powder between 500 and 635 mesh sieves. Hot pressing of screened Cu powder was performed at 900 °C in Ar/4 %H 2 atmosphere. XRD and ICP results show that the hot-pressed Cu sample consists of about 5 vol% Cu 2O, which is caused by the presence of oxygen onmore » the surface of the starting Cu powder. Hot pressing the copper powder in a pure hydrogen atmosphere was successful in removing most of the surface oxygen. Our process was also implemented for hot pressing the Cu/W composite. The density of the Cu/W composites hot pressed at 950 °C in pure hydrogen was about 94 % of the theoretical density (TD). The hot-pressed Cu/W composites were further hot isostatic pressed at 1050 °C in argon atmosphere, which results in 99.6 % of the TD with the designed Cu grain size and W particle distribution. Tensile specimens with D-notch were machined using the wire EDM method. Furthermore, the processing and consolidation of these materials will be discussed in detail. The HEDM images are also showed and discussed.« less

Structural, optical, opto-thermal and thermal properties of ZnS–PVA nanofluids synthesized through a radiolytic approach

PubMed Central

Faraji, Nastaran; Mat Hussin, Roslina; Saion, Elias; Yunus, W Mahmood Mat; Behzad, Kasra

2015-01-01

Summary This work describes a fast, clean and low-cost approach to synthesize ZnS–PVA nanofluids consisting of ZnS nanoparticles homogeneously distributed in a PVA solution. The ZnS nanoparticles were formed by the electrostatic force between zinc and sulfur ions induced by gamma irradiation at a dose range from 10 to 50 kGy. Several experimental characterizations were conducted to investigate the physical and chemical properties of the samples. Fourier transform infrared spectroscopy (FTIR) was used to determine the chemical structure and bonding conditions of the final products, transmission electron microscopy (TEM) for determining the shape morphology and average particle size, powder X-ray diffraction (XRD) for confirming the formation and crystalline structure of ZnS nanoparticles, UV–visible spectroscopy for measuring the electronic absorption characteristics, transient hot wire (THW) and photoacoustic measurements for measuring the thermal conductivity and thermal effusivity of the samples, from which, for the first time, the values of specific heat and thermal diffusivity of the samples were then calculated. PMID:25821695

Comparison of the effects of measured and computed thermophysical properties of nanofluids on heat transfer performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duangthongsuk, Weerapun; Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Laboratory; Wongwises, Somchai

2010-07-15

This article reports a comparison of the differences between using measured and computed thermophysical properties to describe the heat transfer performance of TiO{sub 2}-water nanofluids. In this study, TiO{sub 2} nanoparticles with average diameters of 21 nm and a particle volume fraction of 0.2-1 vol.% are used. The thermal conductivity and viscosity of nanofluids were measured by using transient hot-wire apparatus and a Bohlin rotational rheometer, respectively. The well-known correlations for calculating the thermal conductivity and viscosity of nanofluids were used for describing the Nusselt number of nanofluids and compared with the results from the measured data. The results showmore » that use of the models of thermophysical properties for calculating the Nusselt number of nanofluids gave similar results to use of the measured data. Where there is a lack of measured data on thermophysical properties, the most appropriate models for computing the thermal conductivity and viscosity of the nanofluids are the models of Yu and Choi and Wang et al., respectively. (author)« less

Method of measuring the dc electric field and other tokamak parameters

DOEpatents

Fisch, Nathaniel J.; Kirtz, Arnold H.

1992-01-01

A method including externally imposing an impulsive momentum-space flux to perturb hot tokamak electrons thereby producing a transient synchrotron radiation signal, in frequency-time space, and the inference, using very fast algorithms, of plasma parameters including the effective ion charge state Z.sub.eff, the direction of the magnetic field, and the position and width in velocity space of the impulsive momentum-space flux, and, in particular, the dc toroidal electric field.

Significant Transient Mobility of Platinum Clusters via a Hot Precursor State on the Alumina Surface.

PubMed

Beniya, Atsushi; Hirata, Hirohito; Watanabe, Yoshihide

2016-11-17

Relaxation dynamics of hot metal clusters on oxide surfaces play a crucial role in a variety of physical and chemical processes. However, their transient mobility has not been investigated as much as other systems such as atoms and molecules on metal surfaces due to experimental difficulties. To study the role of the transient mobility of clusters on the oxide surface, we investigated the initial adsorption process of size-selected Pt clusters on a thin Al 2 O 3 film. Soft-landing the size-selected clusters while suppressing the thermal migration resulted in the transient migration controlling the initial adsorption states as an isolated and aggregated cluster, as revealed using scanning tunneling microscopy. We demonstrate that transient migration significantly contributes to the initial cluster adsorption process; the cross section for aggregation is seven times larger than the expected value from geometrical considerations, indicating that metal clusters are highly mobile during a energy dissipation process on the oxide surface.

Mechanical properties and aesthetics of FRP orthodontic wire fabricated by hot drawing.

PubMed

Imai, T; Watari, F; Yamagata, S; Kobayashi, M; Nagayama, K; Toyoizumi, Y; Nakamura, S

1998-12-01

The FRP wires 0.5 mm in diameter with a multiple fiber structure were fabricated by drawing the fiber polymer complex at 250 degrees C for an esthetic, transparent orthodontic wire. Biocompatible CaO-P2O5-SiO2-Al2O3 (CPSA) glass fibers of 8-20 microm in diameter were oriented unidirectionally in the longitudinal direction in PMMA matrix. The mechanical properties were investigated by 3-point flexural test. The FRP wire showed sufficient strength and a very good elastic recovery after deformation. Young's modulus and the flexural load at deflection 1 mm were nearly independent of the fiber diameter and linearly increased with the fiber fraction. The dependence on fiber fraction obeys well the rule of mixture. This FRP wire could cover the range of strength corresponding to the conventional metal orthodontic wires from Ni-Ti used in the initial stage of orthodontic treatments to Co-Cr used in the final stage by changing the volume ratio of glass fibers with the same external diameter. The estheticity in external appearance was excellent. Thus the new FRP wire can satisfy both mechanical properties necessary for an orthodontic wire and enough estheticity, which was not possible for the conventional metal wire.

Fast wire per wire X-ray data acquisition system for time-resolved small angle scattering experiments

NASA Astrophysics Data System (ADS)

Epstein, A.; Briquet-Laugier, F.; Sheldon, S.; Boulin, C.

2000-04-01

Most of the X-ray multi-wire gas detectors used at the EMBL Hamburg outstation for time-resolved studies of biological samples are readout, using the delay line method. The main disadvantage of such readout systems is their event rate limitation introduced by the delay line and the required time to digital conversion step. They also lack the possibility to deal with multiple events. To overcome these limitations, a new approach for the complete readout system was introduced. The new linear detection system is based on the wire per wire approach where each individual wire is associated to preamplifier/discriminator/counter electronics channel. High-density, front-end electronics were designed around a fast current sensitive preamplifier. An eight-channel board was designed to include the preamplifiers-discriminators and the differential ECL drivers output stages. The detector front-end consists of 25 boards directly mounted inside the detector assembly. To achieve a time framing resolution as short as 10 /spl mu/s, very fast histogramming is required. The only way to implement this for a high number of channels (200 in our case) is by using a distributed system. The digital part of the system consists of a crate controller, up to 16 acquisition boards (capable of handling fast histogramming for up to 32-channels each) and an optical-link board (based on the Cypress "Hot-Link" chip set). Both the crate controller and the acquisition boards are based on a standard RISC microcontroller (IDT R3081) plug-in board. At present, a dedicated CAMAC module which we developed is used to interface the digital front-end acquisition crate to the host via the optical link.

High speed transition prediction

NASA Technical Reports Server (NTRS)

Gasperas, Gediminis

1992-01-01

The main objective of this work period was to develop, acquire and apply state-of-the-art tools for the prediction of transition at high speeds at NASA Ames. Although various stability codes as well as basic state codes were acquired, the development of a new Parabolized Stability Equation (PSE) code was minimal. The time that was initially allocated for development was used on other tasks, in particular for the Leading Edge Suction problem, in acquiring proficiency in various graphics tools, and in applying these tools to evaluate various Navier-Stokes and Euler solutions. The second objective of this work period was to attend the Transition and Turbulence Workshop at NASA Langley in July and August, 1991. A report on the Workshop follows. From July 8, 1991 to August 2, 1991, the author participated in the Transition and Turbulence Workshop at NASA Langley. For purposes of interest here, analysis can be said to consist of solving simplified governing equations by various analytical methods, such as asymptotic methods, or by use of very meager computer resources. From the composition of the various groups at the Workshop, it can be seen that analytical methods are generally more popular in Great Britain than they are in the U.S., possibly due to historical factors and the lack of computer resources. Experimenters at the Workshop were mostly concerned with subsonic flows, and a number of demonstrations were provided, among which were a hot-wire experiment to probe the boundary layer on a rotating disc, a hot-wire rake to map a free shear layer behind a cylinder, and the use of heating strips on a flat plate to control instability waves and consequent transition. A highpoint of the demonstrations was the opportunity to observe the rather noisy 'quiet' supersonic pilot tunnel in operation.

40 CFR 1065.225 - Intake-air flow meter.

Code of Federal Regulations, 2012 CFR

2012-07-01

... concentrations, if the same signal is used in a chemical-balance calculation to determine work from brake... tube, or a hot-wire anemometer. Note that your overall system for measuring intake-air flow must meet...

Transient corona effects on a wire over the ground

NASA Technical Reports Server (NTRS)

Chen, K. C.

1980-01-01

The nuclear EMP effect on VLF/trailing wire antennas is investigated in relation to new features of corona effects. Previous experimental results on transmission lines with corona under E 80 kV/cm recorded in the nanosecond time frame are analyzed. A nonlinear macroscopic model which describes a transmission line with corona is discussed. The model not only accounts for overall waveform, but also describes the sharp changes in the waveform associated with the corona onset.

Charge carrier trapping and acoustic phonon modes in single CdTe nanowires.

PubMed

Lo, Shun Shang; Major, Todd A; Petchsang, Nattasamon; Huang, Libai; Kuno, Masaru K; Hartland, Gregory V

2012-06-26

Semiconductor nanostructures produced by wet chemical synthesis are extremely heterogeneous, which makes single particle techniques a useful way to interrogate their properties. In this paper the ultrafast dynamics of single CdTe nanowires are studied by transient absorption microscopy. The wires have lengths of several micrometers and lateral dimensions on the order of 30 nm. The transient absorption traces show very fast decays, which are assigned to charge carrier trapping into surface defects. The time constants vary for different wires due to differences in the energetics and/or density of surface trap sites. Measurements performed at the band edge compared to the near-IR give slightly different time constants, implying that the dynamics for electron and hole trapping are different. The rate of charge carrier trapping was observed to slow down at high carrier densities, which was attributed to trap-state filling. Modulations due to the fundamental and first overtone of the acoustic breathing mode were also observed in the transient absorption traces. The quality factors for these modes were similar to those measured for metal nanostructures, and indicate a complex interaction with the environment.

Morphological, compositional, and geometrical transients of V-groove quantum wires formed during metalorganic vapor-phase epitaxy

NASA Astrophysics Data System (ADS)

Dimastrodonato, Valeria; Pelucchi, Emanuele; Zestanakis, Panagiotis A.; Vvedensky, Dimitri D.

2013-07-01

We present a theoretical model of the formation of self-limited (Al)GaAs quantum wires within V-grooves on GaAs(001) substrates during metalorganic vapor-phase epitaxy. We identify the facet-dependent rates of the kinetic processes responsible for the formation of the self-limiting profile, which is accompanied by Ga segregation along the axis perpendicular to the bottom of the original template, and analyze their interplay with the facet geometry in the transient regime. A reduced model is adopted for the evolution of the patterned profile, as determined by the angle between the different crystallographic planes as a function of the growth conditions. Our results provide a comprehensive phenomenological understanding of the self-ordering mechanism on patterned surfaces which can be harnessed for designing the quantum optical properties of low-dimensional systems.

Evaluation of electrical conductivity of Cu and Al through sub microsecond underwater electrical wire explosion

NASA Astrophysics Data System (ADS)

Sheftman, D.; Shafer, D.; Efimov, S.; Krasik, Ya. E.

2012-03-01

Sub-microsecond timescale underwater electrical wire explosions using Cu and Al materials have been conducted. Current and voltage waveforms and time-resolved streak images of the discharge channel, coupled to 1D magneto-hydrodynamic simulations, have been used to determine the electrical conductivity of the metals for the range of conditions between hot liquid metal and strongly coupled non-ideal plasma, in the temperature range of 10-60 KK. The results of these studies showed that the conductivity values obtained are typically lower than those corresponding to modern theoretical electrical conductivity models and provide a transition between the conductivity values obtained in microsecond time scale explosions and those obtained in nanosecond time scale wire explosions. In addition, the measured wire expansion shows good agreement with equation of state tables.

Study of the structure of turbulent shear flows at supersonic speeds and high Reynolds number

NASA Technical Reports Server (NTRS)

Smits, A. J.; Bogdonoff, S. M.

1984-01-01

A major effort to improve the accuracies of turbulence measurement techniques is described including the development and testing of constant temperature hot-wire anemometers which automatically compensate for frequency responses. Calibration and data acquisition techniques for normal and inclined wires operated in the constant temperature mode, flow geometries, and physical models to explain the observed behavior of flows are discussed, as well as cooperation with computational groups in the calculation of compression corner flows.

Experimental investigation of turbulent flow through a circular-to-rectangular transition duct. Ph.D. Thesis - Washington Univ.

NASA Technical Reports Server (NTRS)

Davis, David O.

1991-01-01

Steady, incompressible, turbulent, swirl-free flow through a circular-to-rectangular transition duck was studied experimentally. The cross-sectional area remains the same at the exit as at the inlet, but varies through the transition section to a maximum value approximately 15 percent above the inlet value. The cross-sectional geometry everywhere along the duct is defined by the equation of a superellipse. Mean and turbulence data were accumulated utilizing pressure and hot-wire instrumentation at five stations along the test section. Data are presented for operating bulk Reynolds numbers of 88,000 and 390,000. Measured quantities include total and static pressure, the three components of the mean velocity vector, and the six components of the Reynolds stress tensor. In addition to the transition duct measurements, a hot-wire technique which relies on the sequential use of single rotatable normal and slant-wire probes was proposed. The technique is applicable for measurement of the total mean velocity vector and the complete Reynolds stress tensor when the primary flow is arbitrarily skewed relative to a plane which lies normal to the probe axis of rotation.

Transport of energy by ultraintense laser-generated electrons in nail-wire targets

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ma, T.; Lawrence Livermore National Laboratory, Livermore, California 94550; Key, M. H.

2009-11-15

Nail-wire targets (20 {mu}m diameter copper wires with 80 {mu}m hemispherical head) were used to investigate energy transport by relativistic fast electrons generated in intense laser-plasma interactions. The targets were irradiated using the 300 J, 1 ps, and 2x10{sup 20} W{center_dot}cm{sup -2} Vulcan laser at the Rutherford Appleton Laboratory. A spherically bent crystal imager, a highly ordered pyrolytic graphite spectrometer, and single photon counting charge-coupled device gave absolute Cu K{alpha} measurements. Results show a concentration of energy deposition in the head and an approximately exponential fall-off along the wire with about 60 {mu}m 1/e decay length due to resistive inhibition.more » The coupling efficiency to the wire was 3.3{+-}1.7% with an average hot electron temperature of 620{+-}125 keV. Extreme ultraviolet images (68 and 256 eV) indicate additional heating of a thin surface layer of the wire. Modeling using the hybrid E-PLAS code has been compared with the experimental data, showing evidence of resistive heating, magnetic trapping, and surface transport.« less

Methods of measurement for semiconductor materials, process control, and devices

NASA Technical Reports Server (NTRS)

Bullis, W. M. (Editor)

1971-01-01

The development of methods of measurement for semiconductor materials, process control, and devices is discussed. The following subjects are also presented: (1) demonstration of the high sensitivity of the infrared response technique by the identification of gold in a germanium diode, (2) verification that transient thermal response is significantly more sensitive to the presence of voids in die attachment than steady-state thermal resistance, and (3) development of equipment for determining susceptibility of transistors to hot spot formation by the current-gain technique.

Determination of the initial exothermic reaction of shredded tyres with wire content.

PubMed

Sellasie, Kassahun G; Moo-Young, Horace K; Lloyd, Thomas

2004-10-01

This paper presents the cause of exothermic reactions in shredded tyre with exposed wire content in shredded tyre piles. Data indicate that the oxidation of exposed steel wires is the exothermic reaction in shredded tyre embankments. This would lead to spontaneous combustion. Reaction of the steel with the sulphur or the carbon black appears not to be the source of the exothermic. Laboratory tests have been conducted to determine the heat transfer properties of the materials that compose tyres (i.e., tyre rubber and wires) by using a hot-plate apparatus. In addition, one-dimensional heat conduction experiments were conducted to compare the flow of heat through the materials while varying the physical and environmental conditions. The physical conditions were the size of tyre shred, water content, and wire contents. An exothermic reaction occurred when exposed wire was present but not when it was absent. A one-dimensional heat transfer equation was developed, and parametric studies were conducted to verify the laboratory model. Exothermic reaction was found to increase linearly with temperature, size and shape of the shredded tyres, density, amount of wire in shredded tyres, and water content.

A new tubular hot-wire CVD for diamond coating

NASA Astrophysics Data System (ADS)

Motahari, Hamid; Bellah, Samad Moemen; Malekfar, Rasoul

2017-06-01

A new tubular hot-wire chemical vapor deposition (HWCVD) system using a tubular quartz vacuum chamber has been fabricated. The filaments in this system can heat the substrate and act as a gas activator and thermally activator for gas species at the same time. The nano- and microcrystalline diamond coatings on the surface of steel AISI 316 substrates have been grown. To assess the results, SEM and FESEM images and Raman spectroscopy investigations have been applied. The results reveal that micro- and nanocrystalline diamond structures have been formed in the coatings, but the disordered diamond and some non-diamond phases, such as graphitic carbons, are also present in the coating layers. The analytical measurements show the growth of diamond films with well-faceted crystals in (111) direction. However, intrinsic stress, secondary nucleation, and poor adhesion are the main issues of future research for this new designed HWCVD.

"Hot-wire" microfluidic flowmeter based on a microfiber coupler.

PubMed

Yan, Shao-Cheng; Liu, Zeng-Yong; Li, Cheng; Ge, Shi-Jun; Xu, Fei; Lu, Yan-Qing

2016-12-15

Using an optical microfiber coupler (MC), we present a microfluidic platform for strong direct or indirect light-liquid interaction by wrapping a MC around a functionalized capillary. The light propagating in the MC and the liquid flowing in the capillary can be combined and divorced smoothly, keeping a long-distance interaction without the conflict of input and output coupling. Using this approach, we experimentally demonstrate a "hot-wire" microfluidic flowmeter based on a gold-integrated helical MC device. The microfluid inside the glass channel takes away the heat, then cools the MC and shifts the resonant wavelength. Due to the long-distance interaction and high temperature sensitivity, the proposed microfluidic flowmeter shows an ultrahigh flow rate sensitivity of 2.183 nm/(μl/s) at a flow rate of 1 μl/s. The minimum detectable change of the flow rate is around 9 nl/s at 1 μl/s.

Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel

PubMed Central

Toribio, Jesús; González, Beatriz; Matos, Juan-Carlos

2015-01-01

In this paper, a fracto-metallographic analysis was performed on the cracked specimens of cold drawn pearlitic steel subjected to fatigue tests. Fatigue cracks are transcollonial and exhibit a preference for fracturing pearlitic lamellae, with non-uniform crack opening displacement values, micro-discontinuities, branchings, bifurcations and frequent local deflections that create microstructural roughness. At the micro-level, the cold drawn pearlitic steel exhibits higher micro-roughness than the hot rolled bar (this is a consequence of the manufacturing process by cold drawing), so that the actual fractured surface in the cold drawn wire is greater than that in the hot rolled bar, due to the fact that the crack deflection events are more frequent and with higher angle in the former (the heavily drawn prestressing steel wire). These findings show the relevant role on the manufacturing process by cold drawing in the fatigue crack propagation in pearlitic steel. PMID:28793647

Different approaches to modeling the LANSCE H{sup −} ion source filament performance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Draganic, I. N., E-mail: draganic@lanl.gov; O’Hara, J. F.; Rybarcyk, L. J.

2016-02-15

An overview of different approaches to modeling of hot tungsten filament performance in the Los Alamos Neutron Science Center (LANSCE) H{sup −} surface converter ion source is presented. The most critical components in this negative ion source are two specially shaped wire filaments heated up to the working temperature range of 2600 K–2700 K during normal beam production. In order to prevent catastrophic filament failures (creation of hot spots, wire breaking, excessive filament deflection towards source body, etc.) and to improve understanding of the material erosion processes, we have simulated the filament performance using three different models: a semi-empirical model,more » a thermal finite-element analysis model, and an analytical model. Results of all three models were compared with data taken during LANSCE beam production. The models were used to support the recent successful transition from the beam pulse repetition rate of 60 Hz–120 Hz.« less

Analysis of Fatigue Crack Paths in Cold Drawn Pearlitic Steel.

PubMed

Toribio, Jesús; González, Beatriz; Matos, Juan-Carlos

2015-11-04

In this paper, a fracto-metallographic analysis was performed on the cracked specimens of cold drawn pearlitic steel subjected to fatigue tests. Fatigue cracks are transcollonial and exhibit a preference for fracturing pearlitic lamellae, with non-uniform crack opening displacement values, micro-discontinuities, branchings, bifurcations and frequent local deflections that create microstructural roughness. At the micro-level, the cold drawn pearlitic steel exhibits higher micro-roughness than the hot rolled bar (this is a consequence of the manufacturing process by cold drawing), so that the actual fractured surface in the cold drawn wire is greater than that in the hot rolled bar, due to the fact that the crack deflection events are more frequent and with higher angle in the former (the heavily drawn prestressing steel wire). These findings show the relevant role on the manufacturing process by cold drawing in the fatigue crack propagation in pearlitic steel.

Different approaches to modeling the LANSCE H- ion source filament performance

NASA Astrophysics Data System (ADS)

Draganic, I. N.; O'Hara, J. F.; Rybarcyk, L. J.

2016-02-01

An overview of different approaches to modeling of hot tungsten filament performance in the Los Alamos Neutron Science Center (LANSCE) H- surface converter ion source is presented. The most critical components in this negative ion source are two specially shaped wire filaments heated up to the working temperature range of 2600 K-2700 K during normal beam production. In order to prevent catastrophic filament failures (creation of hot spots, wire breaking, excessive filament deflection towards source body, etc.) and to improve understanding of the material erosion processes, we have simulated the filament performance using three different models: a semi-empirical model, a thermal finite-element analysis model, and an analytical model. Results of all three models were compared with data taken during LANSCE beam production. The models were used to support the recent successful transition from the beam pulse repetition rate of 60 Hz-120 Hz.

Highly Sensitive Hot-Wire Anemometry Based on Macro-Sized Double-Walled Carbon Nanotube Strands.

PubMed

Wang, Dingqu; Xiong, Wei; Zhou, Zhaoying; Zhu, Rong; Yang, Xing; Li, Weihua; Jiang, Yueyuan; Zhang, Yajun

2017-08-01

This paper presents a highly sensitive flow-rate sensor with carbon nanotubes (CNTs) as sensing elements. The sensor uses micro-size centimeters long double-walled CNT (DWCNT) strands as hot-wires to sense fluid velocity. In the theoretical analysis, the sensitivity of the sensor is demonstrated to be positively related to the ratio of its surface. We assemble the flow sensor by suspending the DWCNT strand directly on two tungsten prongs and dripping a small amount of silver glue onto each contact between the DWCNT and the prongs. The DWCNT exhibits a positive TCR of 1980 ppm/K. The self-heating effect on the DWCNT was observed while constant current was applied between the two prongs. This sensor can evidently respond to flow rate, and requires only several milliwatts to operate. We have, thus far, demonstrated that the CNT-based flow sensor has better sensitivity than the Pt-coated DWCNT sensor.

Properties of Nanocrystalline Cubic Silicon Carbide Thin Films Prepared by Hot-Wire Chemical Vapor Deposition Using SiH4/CH4/H2 at Various Substrate Temperatures

NASA Astrophysics Data System (ADS)

Tabata, Akimori; Komura, Yusuke; Hoshide, Yoshiki; Narita, Tomoki; Kondo, Akihiro

2008-01-01

Silicon carbide (SiC) thin films were prepared by hot-wire chemical vapor deposition from SiH4/CH4/H2 gases, and the influence of substrate temperature, Ts (104 < Ts < 434 °C), on the properties of the SiC thin films was investigated. X-ray diffraction patterns and Raman scattering spectra revealed that nanocrystalline cubic SiC (nc-3C-SiC) films grew at Ts above 187 °C, while completely amorphous films grew at Ts = 104 °C. Fourier transform infrared absorption spectra revealed that the crystallinity of the nc-3C-SiC was improved with increasing Ts up to 282 °C and remained almost unchanged with a further increase in Ts from 282 to 434 °C. The spin density was reduced monotonically with increasing Ts.

Annealing effects on capacitance-voltage characteristics of a-Si/SiN(x) multilayer prepared using hot-wire chemical vapour deposition.

PubMed

Panchal, A K; Rai, D K; Solanki, C S

2011-04-01

Post-deposition annealing of a-Si/SiN(x) multilayer films at different temperature shows varying shift in high frequency (1 MHz) capacitance-voltage (HFCV) characteristics. Various a-Si/SiN(x) multilayer films were deposited using hot wire chemical vapor deposition (HWCVD) and annealed in the temperature range of 800 to 900 degrees C to precipitate Si quantum dots (Si-QD) in a-Si layers. HFCV measurements of the as-deposited and annealed films in metal-insulator-semiconductor (MIS) structures show hysterisis in C-V curves. The hysteresis in the as-deposited films and annealed films is attributed to charge trapping in Si-dangling bonds in a-Si layer and in Si-QD respectively. The charge trapping density in Si-QD increases with temperature while the interface defects density (D(it)) remains constant.

Terahertz generation from laser-driven ultrafast current propagation along a wire target

NASA Astrophysics Data System (ADS)

Zhuo, H. B.; Zhang, S. J.; Li, X. H.; Zhou, H. Y.; Li, X. Z.; Zou, D. B.; Yu, M. Y.; Wu, H. C.; Sheng, Z. M.; Zhou, C. T.

2017-01-01

Generation of intense coherent THz radiation by obliquely incidenting an intense laser pulse on a wire target is studied using particle-in-cell simulation. The laser-accelerated fast electrons are confined and guided along the surface of the wire, which then acts like a current-carrying line antenna and under appropriate conditions can emit electromagnetic radiation in the THz regime. For a driving laser intensity ˜3 ×1018W /cm2 and pulse duration ˜10 fs, a transient current above 10 KA is produced on the wire surface. The emission-cone angle of the resulting ˜0.15 mJ (˜58 GV/m peak electric field) THz radiation is ˜30∘ . The conversion efficiency of laser-to-THz energy is ˜0.75 % . A simple analytical model that well reproduces the simulated result is presented.

Enhancement of Combustion and Flame Stabilization Using Transient Non-Equilibrium Plasma

DTIC Science & Technology

2007-03-31

cathode spot D = diameter of MGA device D= diffusivity of i’h species d = diameter of arc dcoected= diametrically corrected diameter of arc d.rwwd... cathode and anode, stabilization (4) respectively (Fig. 1). A wire was attached to the cathode , which was separated from the outer anode by 2 mm at the...smallest gap (point (1) in Fig. 1). The wire spiraled progressively closer to the cathode , where it was attached at the largest gap between the two

The wire-mesh sensor as a two-phase flow meter

NASA Astrophysics Data System (ADS)

Shaban, H.; Tavoularis, S.

2015-01-01

A novel gas and liquid flow rate measurement method is proposed for use in vertical upward and downward gas-liquid pipe flows. This method is based on the analysis of the time history of area-averaged void fraction that is measured using a conductivity wire-mesh sensor (WMS). WMS measurements were collected in vertical upward and downward air-water flows in a pipe with an internal diameter of 32.5 mm at nearly atmospheric pressure. The relative frequencies and the power spectral density of area-averaged void fraction were calculated and used as representative properties. Independent features, extracted from these properties using Principal Component Analysis and Independent Component Analysis, were used as inputs to artificial neural networks, which were trained to give the gas and liquid flow rates as outputs. The present method was shown to be accurate for all four encountered flow regimes and for a wide range of flow conditions. Besides providing accurate predictions for steady flows, the method was also tested successfully in three flows with transient liquid flow rates. The method was augmented by the use of the cross-correlation function of area-averaged void fraction determined from the output of a dual WMS unit as an additional representative property, which was found to improve the accuracy of flow rate prediction.

Numerical and experimental investigation of a beveled trailing-edge flow field and noise emission

NASA Astrophysics Data System (ADS)

van der Velden, W. C. P.; Pröbsting, S.; van Zuijlen, A. H.; de Jong, A. T.; Guan, Y.; Morris, S. C.

2016-12-01

Efficient tools and methodology for the prediction of trailing-edge noise experience substantial interest within the wind turbine industry. In recent years, the Lattice Boltzmann Method has received increased attention for providing such an efficient alternative for the numerical solution of complex flow problems. Based on the fully explicit, transient, compressible solution of the Lattice Boltzmann Equation in combination with a Ffowcs-Williams and Hawking aeroacoustic analogy, an estimation of the acoustic radiation in the far field is obtained. To validate this methodology for the prediction of trailing-edge noise, the flow around a flat plate with an asymmetric 25° beveled trailing edge and obtuse corner in a low Mach number flow is analyzed. Flow field dynamics are compared to data obtained experimentally from Particle Image Velocimetry and Hot Wire Anemometry, and compare favorably in terms of mean velocity field and turbulent fluctuations. Moreover, the characteristics of the unsteady surface pressure, which are closely related to the acoustic emission, show good agreement between simulation and experiment. Finally, the prediction of the radiated sound is compared to the results obtained from acoustic phased array measurements in combination with a beamforming methodology. Vortex shedding results in a strong narrowband component centered at a constant Strouhal number in the acoustic spectrum. At higher frequency, a good agreement between simulation and experiment for the broadband noise component is obtained and a typical cardioid-like directivity is recovered.

Electrically excited hot-electron dominated fluorescent emitters using individual Ga-doped ZnO microwires via metal quasiparticle film decoration.

PubMed

Liu, Yang; Jiang, Mingming; Zhang, Zhenzhong; Li, Binghui; Zhao, Haifeng; Shan, Chongxin; Shen, Dezhen

2018-03-28

The generation of hot electrons from metal nanostructures through plasmon decay provided a direct interfacial charge transfer mechanism, which no longer suffers from the barrier height restrictions observed for metal/semiconductor interfaces. Metal plasmon-mediated energy conversion with higher efficiency has been proposed as a promising alternative to construct novel optoelectronic devices, such as photodetectors, photovoltaic and photocatalytic devices, etc. However, the realization of the electrically-driven generation of hot electrons, and the application in light-emitting devices remain big challenges. Here, hybrid architectures comprising individual Ga-doped ZnO (ZnO:Ga) microwires via metal quasiparticle film decoration were fabricated. The hottest spots could be formed towards the center of the wires, and the quasiparticle films were converted into physically isolated nanoparticles by applying a bias onto the wires. Thus, the hot electrons became spatially localized towards the hottest regions, leading to a release of energy in the form of emitting photons. By adjusting the sputtering times and appropriate alloys, such as Au and Ag, wavelength-tunable emissions could be achieved. To exploit the EL emission characteristics, metal plasmons could be used as active elements to mediate the generation of hot electrons from metal nanostructures, which are located in the light-emitting regions, followed by injection into ZnO:Ga microwire-channels; thus, the production of plasmon decay-induced hot-electrons could function as an efficient approach to dominate emission wavelengths. Therefore, by introducing metal nanostructure decoration, individual ZnO:Ga microwires can be used to construct wavelength-tunable fluorescent emitters. The hybrid architectures of metal-ZnO micro/nanostructures offer a fantastic candidate to broaden the potential applications of semiconducting optoelectronic devices, such as photovoltaic devices, photodetectors, optoelectronic sensors, etc.

Research on burnout fault of moulded case circuit breaker based on finite element simulation

NASA Astrophysics Data System (ADS)

Xue, Yang; Chang, Shuai; Zhang, Penghe; Xu, Yinghui; Peng, Chuning; Shi, Erwei

2017-09-01

In the failure event of molded case circuit breaker, overheating of the molded case near the wiring terminal has a very important proportion. The burnout fault has become an important factor restricting the development of molded case circuit breaker. This paper uses the finite element simulation software to establish the model of molded case circuit breaker by coupling multi-physics field. This model can simulate the operation and study the law of the temperature distribution. The simulation results show that the temperature near the wiring terminal, especially the incoming side of the live wire, of the molded case circuit breaker is much higher than that of the other areas. The steady-state and transient simulation results show that the temperature at the wiring terminals is abnormally increased by increasing the contact resistance of the wiring terminals. This is consistent with the frequent occurrence of burnout of the molded case in this area. Therefore, this paper holds that the burnout failure of the molded case circuit breaker is mainly caused by the abnormal increase of the contact resistance of the wiring terminal.

Fiber-optic anemometer based on single-walled carbon nanotube coated tilted fiber Bragg grating.

PubMed

Zhang, Yang; Wang, Fang; Liu, Zigeng; Duan, Zhihui; Cui, Wenli; Han, Jie; Gu, Yiying; Wu, Zhenlin; Jing, Zhenguo; Sun, Changsen; Peng, Wei

2017-10-02

In this work, a novel and simple optical fiber hot-wire anemometer based on single-walled carbon nanotubes (SWCNTs) coated tilted fiber Bragg grating (TFBG) is proposed and demonstrated. For the hot-wire wind speed sensor design, TFBG is an ideal in-fiber sensing structure due to its unique features. It is utilized as both light coupling and temperature sensing element without using any geometry-modified or uncommon fiber, which simplifies the sensor structure. To further enhance the thermal conversion capability, SWCNTs are coated on the surface of the TFBG instead of traditional metallic materials, which have excellent thermal characteristics. When a laser light is pumped into the sensor, the pump light propagating in the core will be easily coupled into cladding of the fiber via the TFBG and strongly absorbed by the SWCNTs thin film. This absorption acts like a hot-wire raising the local temperature of the fiber, which is accurately detected by the TFBG resonance shift. In the experiments, the sensor's performances were investigated and controlled by adjusting the inherent angle of the TFBG, the thickness of SWCNTs film, and the input power of the pump laser. It was demonstrated that the developed anemometer exhibited significant light absorption efficiency up to 93%, and the maximum temperature of the local area on the fiber was heated up to 146.1°C under the relatively low pump power of 97.76 mW. The sensitivity of -0.3667 nm/(m/s) at wind speed of 1.0 m/s was measured with the selected 12° TFBG and 1.6 μm film.

Molten thermoplastic dripping behavior induced by flame spread over wire insulation under overload currents.

PubMed

He, Hao; Zhang, Qixing; Tu, Ran; Zhao, Luyao; Liu, Jia; Zhang, Yongming

2016-12-15

The dripping behavior of the molten thermoplastic insulation of copper wire, induced by flame spread under overload currents, was investigated for a better understanding of energized electrical wire fires. Three types of sample wire, with the same polyethylene insulation thickness and different core diameters, were used in this study. First, overload current effects on the transient one-dimensional wire temperature profile were predicted using simplified theoretical analysis; the heating process and equilibrium temperature were obtained. Second, experiments on the melting characteristics were conducted in a laboratory environment, including drop formation and frequency, falling speed, and combustion on the steel base. Third, a relationship between molten mass loss and volume variation was proposed to evaluate the dripping time and frequency. A strong current was a prerequisite for the wire dripping behavior and the averaged dripping frequency was found to be proportional to the square of the current based on the theoretical and experimental results. Finally, the influence of dripping behavior on the flame propagation along the energized electrical wire was discussed. The flame width, bright flame height and flame spreading velocity presented different behaviors. Copyright © 2016 Elsevier B.V. All rights reserved.

Influence of the intramedullary nail preparation method on nail's mechanical properties and degradation rate.

PubMed

Morawska-Chochół, Anna; Chłopek, Jan; Szaraniec, Barbara; Domalik-Pyzik, Patrycja; Balacha, Ewa; Boguń, Maciej; Kucharski, Rafael

2015-06-01

When it comes to the treatment of long bone fractures, scientists are still investigating new materials for intramedullary nails and different manufacturing methods. Some of the most promising materials used in the field are resorbable polymers and their composites, especially since there is a wide range of potential manufacturing and processing methods. The aim of this work was to select the best manufacturing method and technological parameters to obtain multiphase, and multifunctional, biodegradable intramedullary nails. All composites were based on a poly(l-lactide) matrix. Either magnesium alloy wires or carbon and alginate fibres were introduced in order to reinforce the nails. The polylactide matrix was also modified with tricalcium phosphate and gentamicin sulfate. The composite nails were manufactured using three different methods: forming from solution, injection moulding and hot pressing. The effect of each method of manufacturing on mechanical properties and degradation rate of the nails was evaluated. The study showed that injection moulding provides higher uniformity and homogeneity of the particle-modified polylactide matrix, whereas hot pressing favours applying higher volume fractions of fibres and their better impregnation with the polymer matrix. Thus, it was concluded that the fabrication method should be individually selected dependently on the nail's desired phase composition. Copyright © 2015 Elsevier B.V. All rights reserved.

A semiconductor bridge ignited hot gas piston ejector

NASA Technical Reports Server (NTRS)

Grubelich, M. C.; Bickes, Robert W., Jr.

1993-01-01

The topics are presented in viewgraph form and include the following: semiconductor bridge technology (SCB); SCB philosophy; technology transfer; simplified sketch of SCB; SCB processing; SCB design; SCB test assembly; 5 mJ SCB burst based on a polaroid photograph; micro-convective heat transfer hypothesis; SCB fire set; comparison of SCB and hot-wire actuators; satellite firing sets; logic fire set; SCB smart component; SCB smart firing set; semiconductor design considerations; and the adjustable actuator system.

The performance of hafnium and gadolinium self powered neutron detectors in the TREAT reactor

NASA Astrophysics Data System (ADS)

Imel, G. R.; Hart, P. R.

1996-05-01

The use of gadolinium and hafnium self powered neutron detectors in a transient reactor is described in this paper. The detectors were calibrated to the fission rate of U-235 using calibrated fission chambers; the calibration factors were tested in two reactors in steady state and found to be consistent. Calibration of the detectors in transient reactor conditions was done by using uranium wires that were analyzed by radiochemistry techniques to determine total fissions during the transient. This was correlated to the time-integrated current of the detectors during the transient. A temperature correction factor was derived to account for self-shielding effects in the hafnium and gadolinium detectors. The dynamic response of the detectors under transient conditions was studied, and found to be excellent.

Radioactive hot cell access hole decontamination machine

DOEpatents

Simpson, William E.

1982-01-01

Radioactive hot cell access hole decontamination machine. A mobile housing has an opening large enough to encircle the access hole and has a shielding door, with a door opening and closing mechanism, for uncovering and covering the opening. The housing contains a shaft which has an apparatus for rotating the shaft and a device for independently translating the shaft from the housing through the opening and access hole into the hot cell chamber. A properly sized cylindrical pig containing wire brushes and cloth or other disks, with an arrangement for releasably attaching it to the end of the shaft, circumferentially cleans the access hole wall of radioactive contamination and thereafter detaches from the shaft to fall into the hot cell chamber.

40 CFR 53.62 - Test procedure: Full wind tunnel test.

Code of Federal Regulations, 2014 CFR

2014-07-01

... accuracy of 5 percent or better (e.g., hot-wire anemometry). For the wind speeds specified in table F-2 of... candidate sampler as a function of aerodynamic particle diameter (Dae) on semi-logarithmic graph paper where...

40 CFR 53.62 - Test procedure: Full wind tunnel test.

Code of Federal Regulations, 2012 CFR

2012-07-01

... accuracy of 5 percent or better (e.g., hot-wire anemometry). For the wind speeds specified in table F-2 of... candidate sampler as a function of aerodynamic particle diameter (Dae) on semi-logarithmic graph paper where...

40 CFR 53.62 - Test procedure: Full wind tunnel test.

Code of Federal Regulations, 2011 CFR

2011-07-01

... accuracy of 5 percent or better (e.g., hot-wire anemometry). For the wind speeds specified in table F-2 of... candidate sampler as a function of aerodynamic particle diameter (Dae) on semi-logarithmic graph paper where...

40 CFR 53.62 - Test procedure: Full wind tunnel test.

Code of Federal Regulations, 2013 CFR

2013-07-01

... accuracy of 5 percent or better (e.g., hot-wire anemometry). For the wind speeds specified in table F-2 of... candidate sampler as a function of aerodynamic particle diameter (Dae) on semi-logarithmic graph paper where...

Feasibility Study for Casting of High Temperature Refractory Superalloy Composites

NASA Technical Reports Server (NTRS)

Lee, Jonathan A.

1998-01-01

Abstract This study investigated the feasibility of using conventional casting technique to fabricate refractory wires reinforced superalloy composites. These composites were being developed for advanced rocket engine turbine blades and other high temperature applications operating up to 2000 F. Several types of refractory metal wires such as W- Th, W-Re, Mo-Hf-C and W-HF-C reinforced waspaloy were experimentally cast and heat treated at 2000 F up to 48 hrs. Scanning electron microscope analysis was conducted in regions adjacent to the wire-matrix interface to determine the reaction zone and chemical compatibility resulting from material interdiffusion. It was concluded that fabrication using conventional casting may be feasible because the wire-matrix reaction zone thickness was comparable to similar composites produced by arc-sprayed monotape with hot isostatic pressing technique, Moreover, it was also found that the chemical compatibility could be improved significantly through a slight modification of the superalloy matrix compositions.

Tungsten dust remobilization under steady-state and transient plasma conditions

DOE PAGES

Ratynskaia, S.; Tolias, P.; De Angeli, M.; ...

2016-11-22

Remobilization is one of the most prominent unresolved fusion dust-relevant issues, strongly related to the lifetime of dust in plasma-wetted regions, the survivability of dust on hot plasma-facing surfaces and the formation of dust accumulation sites. A systematic cross-machine study has been initiated to investigate the remobilization of tungsten micron-size dust from tungsten surfaces implementing a newly developed technique based on controlled pre-adhesion by gas dynamics methods. It has been utilized in a number of devices and has provided new insights on remobilization under steady-state and transient conditions. In conclusion, the experiments are interpreted with contact mechanics theory and heatmore » conduction models.« less

Compartment A123 crews WC (head) looking aft; to forward; note ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

Compartment A-123 crews WC (head) looking aft; to forward; note wire lockers for transient stowage of clothing while showering. (026) - USS Olympia, Penn's Landing, 211 South Columbus Boulevard, Philadelphia, Philadelphia County, PA

Band structure dynamics in indium wires

NASA Astrophysics Data System (ADS)

Chávez-Cervantes, M.; Krause, R.; Aeschlimann, S.; Gierz, I.

2018-05-01

One-dimensional indium wires grown on Si(111) substrates, which are metallic at high temperatures, become insulating below ˜100 K due to the formation of a charge density wave (CDW). The physics of this transition is not conventional and involves a multiband Peierls instability with strong interband coupling. This CDW ground state is readily destroyed with femtosecond laser pulses resulting in a light-induced insulator-to-metal phase transition. The current understanding of this transition remains incomplete, requiring measurements of the transient electronic structure to complement previous investigations of the lattice dynamics. Time- and angle-resolved photoemission spectroscopy with extreme ultraviolet radiation is applied to this end. We find that the transition from the insulating to the metallic band structure occurs within ˜660 fs, which is a fraction of the amplitude mode period. The long lifetime of the transient state (>100 ps) is attributed to trapping in a metastable state in accordance with previous work.

The three-dimensional compressible flow in a radial inflow turbine scroll

NASA Technical Reports Server (NTRS)

Hamed, A.; Tabakoff, W.; Malak, M.

1984-01-01

This work presents the results of an analytical study and an experimental investigation of the three-dimensional flow in a turbine scroll. The finite element method is used in the iterative numerical solution of the locally linearized governing equations for the three-dimensional velocity potential field. The results of the numerical computations are compared with the experimental measurements in the scroll cross sections, which were obtained using laser Doppler velocimetry and hot wire techniques. The results of the computations show a variation in the flow conditions around the rotor periphery which was found to depend on the scroll geometry.

Transient Thermal Response of Lightweight Cementitious Composites Made with Polyurethane Foam Waste

NASA Astrophysics Data System (ADS)

Kismi, M.; Poullain, P.; Mounanga, P.

2012-07-01

The development of low-cost lightweight aggregate (LWA) mortars and concretes presents many advantages, especially in terms of lightness and thermal insulation performances of structures. Low-cost LWA mainly comes from the recovery of vegetal or plastic wastes. This article focuses on the characterization of the thermal conductivity of innovative lightweight cementitious composites made with fine particles of rigid polyurethane (PU) foam waste. Five mortars were prepared with various mass substitution rates of cement with PU-foam particles. Their thermal conductivity was measured with two transient methods: the heating-film method and the hot-disk method. The incorporation of PU-foam particles causes a reduction of up to 18 % of the mortar density, accompanied by a significant improvement of the thermal insulating performance. The effect of segregation on the thermal properties of LWA mortars due to the differences of density among the cementitious matrix, sand, and LWA has also been quantified. The application of the hot-disk method reveals a gradient of thermal conductivity along the thickness of the specimens, which could be explained by a non-uniform repartition of fine PU-foam particles and mineral aggregates within the mortars. The results show a spatial variation of the thermal conductivity of the LWA mortars, ranging from 9 % to 19 %. However, this variation remains close to or even lower than that observed on a normal weight aggregate mortar. Finally, a self-consistent approach is proposed to estimate the thermal conductivity of PU-foam cement-based composites.

Long lifetimes of ultrahot particles in interacting Fermi systems

NASA Astrophysics Data System (ADS)

Bard, M.; Protopopov, I. V.; Mirlin, A. D.

2018-05-01

The energy dependence of the relaxation rate of hot electrons due to interaction with the Fermi sea is studied. We consider 2D and 3D systems, quasi-1D quantum wires with multiple transverse bands, as well as single-channel 1D wires. Our analysis includes both spinful and spin-polarized setups, with short-range and Coulomb interactions. We show that, quite generally, the relaxation rate is a nonmonotonic function of the electron energy and decays as a power law at high energies. In other words, ultrahot electrons regain their coherence with increasing energy. Such a behavior was observed in a recent experiment on multiband quantum wires, J. Reiner et al., Phys. Rev. X 7, 021016 (2017)., 10.1103/PhysRevX.7.021016

New continuous recording procedure of holographic information on transient phenomena

NASA Astrophysics Data System (ADS)

Nagayama, Kunihito; Nishihara, H. Keith; Murakami, Terutoshi

1992-09-01

A new method for continuous recording of holographic information, 'streak holography,' is proposed. This kind of record can be useful for velocity and acceleration measurement as well as for observing a moving object whose trajectory cannot be predicted in advance. A very high speed camera system has been designed and constructed for streak holography. A ring-shaped 100-mm-diam film has been cut out from the high-resolution sheet film and mounted on a thin duralmin disk, which has been driven to rotate directly by an air-turbine spindle. Attainable streak velocity is 0.3 mm/microsecond(s) . A direct film drive mechanism makes it possible to use a relay lens system of extremely small f number. The feasibility of the camera system has been demonstrated by observing several transient events, such as the forced oscillation of a wire and the free fall of small glass particles, using an argon-ion laser as a light source.

Terahertz generation from laser-driven ultrafast current propagation along a wire target.

PubMed

Zhuo, H B; Zhang, S J; Li, X H; Zhou, H Y; Li, X Z; Zou, D B; Yu, M Y; Wu, H C; Sheng, Z M; Zhou, C T

2017-01-01

Generation of intense coherent THz radiation by obliquely incidenting an intense laser pulse on a wire target is studied using particle-in-cell simulation. The laser-accelerated fast electrons are confined and guided along the surface of the wire, which then acts like a current-carrying line antenna and under appropriate conditions can emit electromagnetic radiation in the THz regime. For a driving laser intensity ∼3×10^{18}W/cm^{2} and pulse duration ∼10 fs, a transient current above 10 KA is produced on the wire surface. The emission-cone angle of the resulting ∼0.15 mJ (∼58 GV/m peak electric field) THz radiation is ∼30^{∘}. The conversion efficiency of laser-to-THz energy is ∼0.75%. A simple analytical model that well reproduces the simulated result is presented.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wolf, Steffen; Gerwert, Klaus, E-mail: gerwert@bph.rub.de; Department of Biophysics, Chinese Academy of Sciences, Max-Planck-Gesellschaft Partner Institute for Computational Biology, 320 Yue Yang Road, 200031 Shanghai

Proton conduction along protein-bound “water wires” is an essential feature in membrane proteins. Here, we analyze in detail a transient water wire, which conducts protons via a hydrophobic barrier within a membrane protein to create a proton gradient. It is formed only for a millisecond out of three water molecules distributed at inactive positions in a polar environment in the ground state. The movement into a hydrophobic environment causes characteristic shifts of the water bands reflecting their different chemical properties. These band shifts are identified by time-resolved Fourier Transform Infrared difference spectroscopy and analyzed by biomolecular Quantum Mechanical/Molecular Mechanical simulations.more » A non-hydrogen bonded (“dangling”) O–H stretching vibration band and a broad continuum absorbance caused by a combined vibration along the water wire are identified as characteristic marker bands of such water wires in a hydrophobic environment. The results provide a basic understanding of water wires in hydrophobic environments.« less

Fabrication and evaluation of low fiber content alumina fiber/aluminum composites

NASA Technical Reports Server (NTRS)

Hack, J. E.; Strempek, G. C.

1980-01-01

The mechanical fabrication of low volume percent fiber, polycrystalline alumina fiber reinforced aluminum composites was accomplished. Wire preform material was prepared by liquid-metal infiltration of alumina fiber bundles. The wires were subsequently encapsulated with aluminum foil and fabricated into bulk composite material by hot-drawing. Extensive mechanical, thermal and chemical testing was conducted on preform and bulk material to develop a process and material data base. In addition, a preliminary investigation of mechanical forming of bulk alumina fiber reinforced aluminum composite material was conducted.

Supply-demand mismatch transients in susceptible peri-infarct hot zones explain the origins of spreading injury depolarizations.

PubMed

von Bornstädt, Daniel; Houben, Thijs; Seidel, Jessica L; Zheng, Yi; Dilekoz, Ergin; Qin, Tao; Sandow, Nora; Kura, Sreekanth; Eikermann-Haerter, Katharina; Endres, Matthias; Boas, David A; Moskowitz, Michael A; Lo, Eng H; Dreier, Jens P; Woitzik, Johannes; Sakadžić, Sava; Ayata, Cenk

2015-03-04

Peri-infarct depolarizations (PIDs) are seemingly spontaneous spreading depression-like waves that negatively impact tissue outcome in both experimental and human stroke. Factors triggering PIDs are unknown. Here, we show that somatosensory activation of peri-infarct cortex triggers PIDs when the activated cortex is within a critical range of ischemia. We show that the mechanism involves increased oxygen utilization within the activated cortex, worsening the supply-demand mismatch. We support the concept by clinical data showing that mismatch predisposes stroke patients to PIDs as well. Conversely, transient worsening of mismatch by episodic hypoxemia or hypotension also reproducibly triggers PIDs. Therefore, PIDs are triggered upon supply-demand mismatch transients in metastable peri-infarct hot zones due to increased demand or reduced supply. Based on the data, we propose that minimizing sensory stimulation and hypoxic or hypotensive transients in stroke and brain injury would reduce PID incidence and their adverse impact on outcome. Copyright © 2015 Elsevier Inc. All rights reserved.

Supply-demand mismatch transients in susceptible peri-infarct hot zones explain the origin of spreading injury depolarizations

PubMed Central

von Bornstädt, Daniel; Houben, Thijs; Seidel, Jessica; Zheng, Yi; Dilekoz, Ergin; Qin, Tao; Sandow, Nora; Kura, Sreekanth; Eikermann-Haerter, Katharina; Endres, Matthias; Boas, David A.; Moskowitz, Michael A.; Lo, Eng H.; Dreier, Jens P.; Woitzik, Johannes; Sakadžić, Sava; Ayata, Cenk

2015-01-01

SUMMARY Peri-infarct depolarizations (PIDs) are seemingly spontaneous spreading depression-like waves that negatively impact tissue outcome in both experimental and human stroke. Factors triggering PIDs are unknown. Here, we show that somatosensory activation of peri-infarct cortex triggers PIDs when the activated cortex is within a critical range of ischemia. We show that the mechanism involves increased oxygen utilization within the activated cortex, worsening the supply-demand mismatch. We support the concept by clinical data showing that mismatch predisposes to PIDs in human stroke as well. Conversely, transient worsening of mismatch by episodic hypoxemia or hypotension also reproducibly triggers PIDs. Therefore, PIDs are triggered upon supply-demand mismatch transients in metastable peri-infarct hot zones due to increased demand or reduced supply. Based on the data, we propose that minimizing sensory stimulation and hypoxic or hypotensive transients in stroke and brain injury would reduce PID incidence and their adverse impact on outcome. PMID:25741731

Theory and performance of plated thermocouples.

NASA Technical Reports Server (NTRS)

Pesko, R. N.; Ash, R. L.; Cupschalk, S. G.; Germain, E. F.

1972-01-01

A theory has been developed to describe the performance of thermocouples which have been formed by electroplating portions of one thermoelectric material with another. The electroplated leg of the thermocouple was modeled as a collection of infinitesimally small homogeneous thermocouples connected in series. Experiments were performed using several combinations of Constantan wire sizes and copper plating thicknesses. A transient method was used to develop the thermoelectric calibrations, and the theory was found to be in quite good agreement with the experiments. In addition, data gathered in a Soviet experiment were also found to be in close agreement with the theory.

Experimental Study of Boundary Layer Behavior in a Simulated Low Pressure Turbine. Degree awarded by the University of Toledo, May 1998

NASA Technical Reports Server (NTRS)

Shyne, Rickey J.

1998-01-01

A detailed investigation of the flow physics occurring on the suction side of a simulated Low Pressure Turbine (LPT) blade was performed. A contoured upper wall was designed to simulate the pressure distribution of an actual LPT blade onto a flat plate. The experiments were carried out at Reynolds numbers of 100,000 and 250,000 with three levels of freestream turbulence. Freestream turbulence levels ranging from 0.8% to 3% was used in this experiment. Smoke-wire flow visualization data was used to confirm that the boundary layer was separated and formed a bubble. Hot-wires (single and x-wire) and surface mounted hot-film gases and static pressure taps were used to map the flowfield. The transition process over the separated flow region is observed to be similar to a laminar free shear layer flow with the formation of a large coherent eddy structure. For each condition, the locations defining the separation bubble were determined by careful examination of pressure and mean velocity profile data. Transition onset location and length determined from intermittency profiles decrease as freestream turbulence levels increase. Additionally, the length and height of the laminar separation bubbles were observed to be inversely proportional to the levels of freestream turbulence.

Effect of Free Stream Turbulence on Flow Past a Circular Cylinder at Low Reynolds Numbers

NASA Astrophysics Data System (ADS)

Kumar, Vinoth; Singh, Mrityunjay; Thangadurai, Murugan; Chatterjee, P. K.

2018-01-01

Circular cylinders experiencing different upstream flow conditions have been studied for low Reynolds numbers using hot-wire anemometry and smoke flow visualizations. The upstream condition of the cylinder in the test section is varied using a wire mesh placed at the entrance of the test section. The Reynolds number is varied by varying the diameter of the cylinder and the mean velocity in the test section. Smooth cylinders of diameter varying from 1.25 to 25 mm are used in the present study. A multi-channel hot-wire anemometry is used for measuring the fluctuating velocities in the test section and the wake behind the cylinder. The sectional views of the wake behind the cylinder are obtained using a 4 MP CCD camera, 200 mJ pulsed laser and a fog generator. The flow quality in the test section is examined using higher order turbulence statistics. The effect of free stream turbulence levels and their frequencies on wake structures and the shedding frequencies of circular cylinders are studied in detail. It has been observed that the alteration in wake structure and the shedding frequency depend strongly on the frequencies and the amplitudes of upstream disturbances besides the diameter of the circular cylinder.

Longitudinal magnet forces?

NASA Astrophysics Data System (ADS)

Graneau, P.

1984-03-01

The Ampere electrodynamics of metallic conductors and experiments supporting it predict that the interaction of a current-carrying wire with its own magnetic field should produce longitudinal mechanical forces in the conductor, existing in addition to the transverse Lorentz forces. The longitudinal forces should stretch the conductor and have been referred to as Ampere tension. In 1964 it was discovered that a current pulse would break a straight copper wire into many fragments without visible melting. A metallurgical examination of the pieces confirmed that the metal parted in the solid state. The same observation has now been made with aluminum wires. In the latest experiments the wire was bent into a semicircle and arc-connected to a capacitor discharge circuit. The arc connections ruled out rupture by Lorentz hoop tension and indicated the longitudinal forces may also arise in circular magnet windings. Explanations of wire fragmentation by thermal shock, longitudinal stress waves, Lorentz pinch-off, bending stresses, and material defects have been considered and found unconvincing. Computed Ampere tensions would be sufficient to fracture hot wires. The Ampere tension would double the hoop tension normally expected in dipole magnets. This should be borne in mind in the design of large dipole magnets contemplated for MHD power generators and railgun accelerators.

Appraisal of an Array TEM Method in Detecting a Mined-Out Area Beneath a Conductive Layer

NASA Astrophysics Data System (ADS)

Li, Hai; Xue, Guo-qiang; Zhou, Nan-nan; Chen, Wei-ying

2015-10-01

The transient electromagnetic method has been extensively used for the detection of mined-out area in China for the past few years. In the cases that the mined-out area is overlain by a conductive layer, the detection of the target layer is difficult with a traditional loop source TEM method. In order to detect the target layer in this condition, this paper presents a newly developed array TEM method, which uses a grounded wire source. The underground current density distribution and the responses of the grounded wire source TEM configuration are modeled to demonstrate that the target layer is detectable in this condition. The 1D OCCAM inversion routine is applied to the synthetic single station data and common middle point gather. The result reveals that the electric source TEM method is capable of recovering the resistive target layer beneath the conductive overburden. By contrast, the conductive target layer cannot be recovered unless the distance between the target layer and the conductive overburden is large. Compared with inversion result of the single station data, the inversion of common middle point gather can better recover the resistivity of the target layer. Finally, a case study illustrates that the array TEM method is successfully applied in recovering a water-filled mined-out area beneath a conductive overburden.

Laser Brazing with Beam Scanning: Experimental and Simulative Analysis

NASA Astrophysics Data System (ADS)

Heitmanek, M.; Dobler, M.; Graudenz, M.; Perret, W.; Göbel, G.; Schmidt, M.; Beyer, E.

Laser beam brazing with copper based filler wire is a widely established technology for joining zinc-coated steel plates in the body-shop. Successful applications are the divided tailgate or the zero-gap joint, which represents the joint between the side panel and the roof-top of the body-in-white. These joints are in direct view to the customer, and therefore have to fulfil highest optical quality requirements. For this reason a stable and efficient laser brazing process is essential. In this paper the current results on quality improvement due to one dimensional laser beam deflections in feed direction are presented. Additionally to the experimental results a transient three-dimensional simulation model for the laser beam brazing process is taken into account. With this model the influence of scanning parameters on filler wire temperature and melt pool characteristics is analyzed. The theoretical predictions are in good accordance with the experimental results. They show that the beam scanning approach is a very promising method to increase process stability and seam quality.

Computer animation of modal and transient vibrations

NASA Technical Reports Server (NTRS)

Lipman, Robert R.

1987-01-01

An interactive computer graphics processor is described that is capable of generating input to animate modal and transient vibrations of finite element models on an interactive graphics system. The results from NASTRAN can be postprocessed such that a three dimensional wire-frame picture, in perspective, of the finite element mesh is drawn on the graphics display. Modal vibrations of any mode shape or transient motions over any range of steps can be animated. The finite element mesh can be color-coded by any component of displacement. Viewing parameters and the rate of vibration of the finite element model can be interactively updated while the structure is vibrating.

Transient Torque Technique for Viscosity and Electrical Conductivity Determination of Semiconducting Liquids

NASA Technical Reports Server (NTRS)

Li, C.; Scripa, R. N.; Ban, H.; Lin, B.; Su, C.-H.; Lehoczky, S. L.; Feth, S.; Zhu, S.; Curreri, Peter A. (Technical Monitor)

2002-01-01

A novel apparatus based on transient torque technique is constructed in MSFC/NASA. The apparatus uses a 125um diameter quartz fiber as torsion wire. A high sensitive angular detector is implemented to measure the deflection angle of the crucible containing the liquid. A rotating magnetic field (RMF) is used to induce a rotating flow of a conducting or semiconducting melts. By measuring the magnitude and transient behavior of the induced deflection angle, the electrical conductivity and viscosity of the melt can be measured simultaneously. High purity elements namely Hg, Ga, Zn and Te are tested at room temperature and high temperature up to 900 C.

In-flight comparisons of boundary-layer and wake measurement probes for incompressible flow

NASA Technical Reports Server (NTRS)

Mertaugh, L. J., Jr.

1972-01-01

The results are presented of in-flight comparisons of a number of boundary-layer and wake measurement probes suitable for low-speed flight-test investigations. The tested boundary-layer probes included a traversing total-pressure probe and a hot-film probe mounted on an internally-mounted drive mechanism, a curved and a straight boundary-layer rake, and a traversing hot-film probe with an externally-mounted drive mechanism. The wake measuring devices included a traversing, self-aligning probe, a wake rake, and an integrating wake rate. The boundary-layer data are compared with a common reference velocity profile and comments given regarding the accuracy of the static-pressure and total-pressure measurements. Discussions on the various calibration presentations used with hot-wire and hot-film sensors and various aspects of improving the accuracy of hot-film sensor results are given in the appendix of this report.

Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading

DOE PAGES

Barth, Christian; Seeber, B.; Rack, A.; ...

2018-04-26

Understanding the critical current performance variation of Nb 3Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation betweenmore » the void morphology and the electro-mechanical limits measured on different Bronze route Nb 3Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires’ void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Lastly, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation upon mechanical loading.« less

Quantitative correlation between the void morphology of niobium-tin wires and their irreversible critical current degradation upon mechanical loading

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barth, Christian; Seeber, B.; Rack, A.

Understanding the critical current performance variation of Nb 3Sn superconducting wires under mechanical loading is a crucial issue for the design of next generation accelerator and fusion magnets. In these applications, the mechanical properties of the conductors may become a limiting factor due to the strong electro-magnetic forces resulting from the combination of large magnets and intense magnetic fields. In particular, the presence of voids in the superconducting filament structure, which are formed during the fabrication and the reaction heat treatment, determines localized stress concentrations and possibly the formation of cracks. In this work, we demonstrate a quantitative correlation betweenmore » the void morphology and the electro-mechanical limits measured on different Bronze route Nb 3Sn wires. Hot Isostatic Pressing (HIP) prior to the reaction heat treatment is utilized to partially eliminate the voids. The wires’ void distributions - with and without HIP treatment - are detected and statistically analyzed using high energy X-ray micro tomography. The stress concentration due to the shape and distribution of the voids as well as their impact on the electro-mechanical properties are determined through finite element method modeling. Lastly, the results are quantitatively correlated with the experimentally determined limits of the irreversible critical current degradation upon mechanical loading.« less

Modified DHTT Equipment for Crystallization Studies of Mold Slags

NASA Astrophysics Data System (ADS)

Kölbl, Nathalie; Harmuth, Harald; Marschall, Irmtraud

2018-04-01

The double hot thermocouple technique (DHTT) enables simulations of the temperature gradient at near-service conditions during continuous casting of steel. With the equipment applied so far, a rectangular slag film of even thickness often cannot be achieved. Further, the minimum temperature frequently lies within the slag film. Modified equipment can avoid these disadvantages via the following design features. The entire furnace chamber is heated to the selected temperature of the cold wire, and the minimum temperature is not located within the slag film. Furthermore, the shape of the heating wire is improved, which enables mounting of a thin, rectangular slag film between four platinum wires. This modification allows for investigations on transparent and translucent slags. So far, the results from DHTT investigations were represented via snapshots of the samples at certain experimental times. Therefore, appropriate methods for the graphical representation of the results were suggested: the maximum crystallinity, the time related to certain crystallinities with a dependence on the position within the slag film, and the crystal growth rate. The CaO-MgO-Al2O3-SiO2 slag investigated with this equipment was mineralogically examined additionally, and based on thermodynamic calculations, the allocation of temperatures to certain positions within the crystallized slag film was possible.

Development of LaRC (TM): IA thermoplastic polyimide coated aerospace wiring

NASA Technical Reports Server (NTRS)

Keating, Jack

1995-01-01

NASA Langley has invented LaRC(exp TM) IA and IAX which are thermoplastic polyimides with good melting, thermal and chemical resistance properties. It was the objective of this contract to prepare and extrude LaRC (exp TM) polyimide onto aircraft wire and evaluate the polymers performance in this critical application. Based on rheology and chemical resistance studies at Imitec, LaRC (exp TM) IAX melts readily in an extruder, facilitating the manufacture of thin wall coatings. The polyimide does not corode the extruder, develop gel particles nor advance in viscosity. The insulated wire was tested according to MiL-W-22759E test specifications. The resulting wire coated with LaRC (exp TM) IAX displayed exceptional properties: surface resistance, non blocking, non burning, hot fluid resistance, impulse dielectric, insulation resistance, low temperature flexibility, thermal aging, wire weight, dimensions, negligible high temperature shrinkage and stripability. The light weight and other properties merit its application in satellites, missiles and aircraft applications. The extruded IAX results in a polyimide aircraft insulation without seams, outstanding moisture resistance, continuous lengths and abrasion resistance.

Analysis of unmitigated large break loss of coolant accidents using MELCOR code

NASA Astrophysics Data System (ADS)

Pescarini, M.; Mascari, F.; Mostacci, D.; De Rosa, F.; Lombardo, C.; Giannetti, F.

2017-11-01

In the framework of severe accident research activity developed by ENEA, a MELCOR nodalization of a generic Pressurized Water Reactor of 900 MWe has been developed. The aim of this paper is to present the analysis of MELCOR code calculations concerning two independent unmitigated large break loss of coolant accident transients, occurring in the cited type of reactor. In particular, the analysis and comparison between the transients initiated by an unmitigated double-ended cold leg rupture and an unmitigated double-ended hot leg rupture in the loop 1 of the primary cooling system is presented herein. This activity has been performed focusing specifically on the in-vessel phenomenology that characterizes this kind of accidents. The analysis of the thermal-hydraulic transient phenomena and the core degradation phenomena is therefore here presented. The analysis of the calculated data shows the capability of the code to reproduce the phenomena typical of these transients and permits their phenomenological study. A first sequence of main events is here presented and shows that the cold leg break transient results faster than the hot leg break transient because of the position of the break. Further analyses are in progress to quantitatively assess the results of the code nodalization for accident management strategy definition and fission product source term evaluation.

Study of a Novel Method for the Thermolysis of Solutes in Aqueous Solution Using a Low Temperature Bubble Column Evaporator.

PubMed

Shahid, Muhammad; Xue, Xinkai; Fan, Chao; Ninham, Barry W; Pashley, Richard M

2015-06-25

An enhanced thermal decomposition of chemical compounds in aqueous solution has been achieved at reduced solution temperatures. The technique exploits hitherto unrecognized properties of a bubble column evaporator (BCE). It offers better heat transfer efficiency than conventional heat transfer equipment. This is obtained via a continuous flow of hot, dry air bubbles of optimal (1-3 mm) size. Optimal bubble size is maintained by using the bubble coalescence inhibition property of some salts. This novel method is illustrated by a study of thermal decomposition of ammonium bicarbonate (NH4HCO3) and potassium persulfate (K2S2O8) in aqueous solutions. The decomposition occurs at significantly lower temperatures than those needed in bulk solution. The process appears to work via the continuous production of hot (e.g., 150 °C) dry air bubbles, which do not heat the solution significantly but produce a transient hot surface layer around each rising bubble. This causes the thermal decomposition of the solute. The decomposition occurs due to the effective collision of the solute with the surface of the hot bubbles. The new process could, for example, be applied to the regeneration of the ammonium bicarbonate draw solution used in forward osmosis.

Low power consumption mini rotary actuator with SMA wires

NASA Astrophysics Data System (ADS)

Manfredi, Luigi; Huan, Yu; Cuschieri, Alfred

2017-11-01

Shape memory alloys (SMAs) are smart materials widely used as actuators for their high power to weight ratio despite their well-known low energy efficiency and limited mechanical bandwidth. For robotic applications, SMAs exhibit limitations due to high power consumption and limited stroke, varying from 4% to 7% of the total length. Hysteresis, during the contraction and extension cycle, requires a complex control algorithm. On the positive side, the small size and low weight are eminently suited for the design of mini actuators for robotic platforms. This paper describes the design and construction of a light weight and low power consuming mini rotary actuator with on-board contact-less position and force sensors. The design is specifically intended to reduce (i) energy consumption, (ii) dimensions of the sensory system, and (iii) provide a simple control without any need for SMA characterisation. The torque produced is controlled by on-board force sensors. Experiments were performed to investigate the energy consumption and performance (step and sinusoidal angle profiles with a frequency varying from 0.5 to 10 Hz and maximal amplitude of {15}\\circ ). We describe a transient capacitor effect related to the SMA wires during the sinusoidal profile when the active SMA wire is powered and the antagonist one switched-off, resulting in a transient current time varying from 300 to 400 ms.

RAPID COMMUNICATION Time-resolved measurements with a vortex flowmeter in a pulsating turbulent flow using wavelet analysis

NASA Astrophysics Data System (ADS)

Laurantzon, F.; Örlü, R.; Segalini, A.; Alfredsson, P. H.

2010-12-01

Vortex flowmeters are commonly employed in technical applications and are obtainable in a variety of commercially available types. However their robustness and accuracy can easily be impaired by environmental conditions, such as inflow disturbances and/or pulsating conditions. Various post-processing techniques of the vortex signal have been used, but all of these methods are so far targeted on obtaining an improved estimate of the time-averaged bulk velocity. Here, on the other hand, we propose, based on wavelet analysis, a straightforward way to utilize the signal from a vortex shedder to extract the time-resolved and thereby the phase-averaged velocity under pulsatile flow conditions. The method was verified with hot-wire and laser Doppler velocimetry measurements.

Correlation of analytical and experimental hot structure vibration results

NASA Technical Reports Server (NTRS)

Kehoe, Michael W.; Deaton, Vivian C.

1993-01-01

High surface temperatures and temperature gradients can affect the vibratory characteristics and stability of aircraft structures. Aircraft designers are relying more on finite-element model analysis methods to ensure sufficient vehicle structural dynamic stability throughout the desired flight envelope. Analysis codes that predict these thermal effects must be correlated and verified with experimental data. Experimental modal data for aluminum, titanium, and fiberglass plates heated at uniform, nonuniform, and transient heating conditions are presented. The data show the effect of heat on each plate's modal characteristics, a comparison of predicted and measured plate vibration frequencies, the measured modal damping, and the effect of modeling material property changes and thermal stresses on the accuracy of the analytical results at nonuniform and transient heating conditions.

40 CFR 420.127 - Effluent limitations representing the degree of effluent reduction attainable by the application...

Code of Federal Regulations, 2011 CFR

2011-07-01

... GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating Subcategory § 420.127...) (1) 1 Within the range of 6.0 to 9.0. (2) [Reserved] (b) Galvanizing and other coatings—(1) Wire...

40 CFR 420.127 - Effluent limitations representing the degree of effluent reduction attainable by the application...

Code of Federal Regulations, 2010 CFR

2010-07-01

... GUIDELINES AND STANDARDS IRON AND STEEL MANUFACTURING POINT SOURCE CATEGORY Hot Coating Subcategory § 420.127...) (1) 1 Within the range of 6.0 to 9.0. (2) [Reserved] (b) Galvanizing and other coatings—(1) Wire...

Cannabinoid hyperemesis syndrome: potential mechanisms for the benefit of capsaicin and hot water hydrotherapy in treatment.

PubMed

Richards, John R; Lapoint, Jeff M; Burillo-Putze, Guillermo

2018-01-01

Cannabinoid hyperemesis syndrome is a clinical disorder that has become more prevalent with increasing use of cannabis and synthetic cannabinoids, and which is difficult to treat. Standard antiemetics commonly fail to alleviate the severe nausea and vomiting characteristic of the syndrome. Curiously, cannabinoid hyperemesis syndrome patients often report dramatic relief of symptoms with hot showers and baths, and topical capsaicin. In this review, we detail the pharmacokinetics and pharmacodynamics of capsaicin and explore possible mechanisms for its beneficial effect, including activation of transient receptor potential vanilloid 1 and neurohumoral regulation. Putative mechanisms responsible for the benefit of hot water hydrotherapy are also investigated. An extensive search of PubMed, OpenGrey, and Google Scholar from inception to April 2017 was performed to identify known and theoretical thermoregulatory mechanisms associated with the endocannabinoid system. The searches resulted in 2417 articles. These articles were screened for relevant mechanisms behind capsaicin and heat activation having potential antiemetic effects. References from the selected articles were also hand-searched. A total of 137 articles were considered relevant and included. Capsaicin: Topical capsaicin is primarily used for treatment of neuropathic pain, but it has also been used successfully in some 20 cases of cannabinoid hyperemesis syndrome. The pharmacokinetics and pharmacodynamics of capsaicin as a transient receptor potential vanilloid 1 agonist may explain this effect. Topical capsaicin has a longer half-life than oral administration, thus its potential duration of benefit is longer. Capsaicin and transient receptor potential vanilloid 1: Topical capsaicin binds and activates the transient receptor potential vanilloid 1 receptor, triggering influx of calcium and sodium, as well as release of inflammatory neuropeptides leading to transient burning, stinging, and itching. This elicits a novel type of desensitization analgesia. Transient receptor potential vanilloid 1 receptors also respond to noxious stimuli, such as heat (>43 °C), acids (pH <6), pain, change in osmolarity, and endovanilloids. The action of topical capsaicin may mimic the effect of heat-activation of transient receptor potential vanilloid 1. Endocannabinoid system and transient receptor potential vanilloid 1: Cannabinoid hyperemesis syndrome may result from a derangement in the endocannabinoid system secondary to chronic exogenous stimulation. The relief of cannabinoid hyperemesis syndrome symptoms from heat and use of transient receptor potential vanilloid 1 agonists suggests a complex interrelation between the endocannabinoid system and transient receptor potential vanilloid 1. Temperature regulation: Hot water hydrotherapy is a mainstay of self-treatment for cannabinoid hyperemesis syndrome patients. This may be explained by heat-induced transient receptor potential vanilloid 1 activation. "Sensocrine" antiemetic effects: Transient receptor potential vanilloid 1 activation by heat or capsaicin results in modulation of tachykinins, somatostatin, pituitary adenylate-cyclase activating polypeptide, and calcitonin gene-related peptide as well as histaminergic, cholinergic, and serotonergic transmission. These downstream effects represent further possible explanations for transient receptor potential vanilloid 1-associated antiemesis. These complex interactions between the endocannabinoid systems and transient receptor potential vanilloid 1, in the setting of cannabinoid receptor desensitization, may yield important clues into the pathophysiology and treatment of cannabinoid hyperemesis syndrome. This knowledge can provide clinicians caring for these patients with additional treatment options that may reduce length of stay, avoid unnecessary imaging and laboratory testing, and decrease the use of potentially harmful medications such as opioids.

Analysis of an existing experiment on the interaction of acoustic waves with a laminar boundary layer

NASA Technical Reports Server (NTRS)

Schopper, M. R.

1982-01-01

The hot-wire anemometer amplitude data contained in the 1977 report of P. J. Shapiro entitled, ""The Influence of Sound Upon Laminar Boundary'' were reevaluated. Because the low-Reynolds number boundary layer disturbance data were misinterpreted, an effort was made to improve the corresponding disturbance growth rate curves. The data are modeled as the sum of upstream and downstream propagating acoustic waves and a wave representing the Tollmien-Schlichting (TS) wave. The amplitude and phase velocity of the latter wave were then adjusted so that the total signal reasonably matched the amplitude and phase angle hot-wire data along the plate laminar boundary layer. The revised rates show growth occurring further upstream than Shapiro found. It appears that the premature growth is due to the adverse pressure gradient created by the shape of the plate. Basic elements of sound propagation in ducts and the experimental and theoretical acoustic-stability literature are reviewed.

Influence of low energy argon plasma treatment on the moisture barrier performance of hot wire-CVD grown SiNx multilayers

NASA Astrophysics Data System (ADS)

Majee, Subimal; Fátima Cerqueira, Maria; Tondelier, Denis; Geffroy, Bernard; Bonnassieux, Yvan; Alpuim, Pedro; Bourée, Jean Eric

2014-01-01

The reliability and stability are key issues for the commercial utilization of organic photovoltaic devices based on flexible polymer substrates. To increase the shelf-lifetime of these devices, transparent moisture barriers of silicon nitride (SiNx) films are deposited at low temperature by hot wire CVD (HW-CVD) process. Instead of the conventional route based on organic/inorganic hybrid structures, this work defines a new route consisting in depositing multilayer stacks of SiNx thin films, each single layer being treated by argon plasma. The plasma treatment allows creating smoother surface and surface atom rearrangement. We define a critical thickness of the single layer film and focus our attention on the effect of increasing the number of SiNx single-layers on the barrier properties. A water vapor transmission rate (WVTR) of 2 × 10-4 g/(m2·day) is reported for SiNx multilayer stack and a physical interpretation of the plasma treatment effect is given.

Automatic hot wire GTA welding of pipe offers speed and increased deposition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sykes, I.; Digiacomo, J.

1995-07-01

Heavy-wall pipe welding for the power and petrochemical industry must meet code requirements. Contractors strive to meet these requirements in the most productive way possible. The challenge put to orbital welding equipment manufacturers is to produce pipe welding equipment that cost-effectively produces code-quality welds. Orbital welding equipment using the GTA process has long produced outstanding quality results but has lacked the deposition rate to compete cost effectively with other manual and semiautomatic processes such as SMAW, FCAW and GMAW. In recent years, significant progress has been made with the use of narrow-groove weld joint designs to reduce weld joint volumemore » and improve welding times. Astro Arc Polysoude, an orbital welding equipment manufacturer based in Sun Valley, Calif., and Nantes, France, has combined the hot wire GTAW process with orbital welding equipment using a narrow-groove weld joint design. Field test results show this process and procedure is a good alternative for many heavy-wall-pipe welding applications.« less

Description of signature scales in a floating wind turbine model wake subjected to varying turbulence intensity

NASA Astrophysics Data System (ADS)

Kadum, Hawwa; Rockel, Stanislav; Holling, Michael; Peinke, Joachim; Cal, Raul Bayon

2017-11-01

The wake behind a floating model horizontal axis wind turbine during pitch motion is investigated and compared to a fixed wind turbine wake. An experiment is conducted in an acoustic wind tunnel where hot-wire data are acquired at five downstream locations. At each downstream location, a rake of 16 hot-wires was used with placement of the probes increasing radially in the vertical, horizontal, and diagonally at 45 deg. In addition, the effect of turbulence intensity on the floating wake is examined by subjecting the wind turbine to different inflow conditions controlled through three settings in the wind tunnel grid, a passive and two active protocols, thus varying in intensity. The wakes are inspected by statistics of the point measurements, where the various length/time scales are considered. The wake characteristics for a floating wind turbine are compared to a fixed turbine, and uncovering its features; relevant as the demand for exploiting deep waters in wind energy is increasing.

A high-performance constant-temperature hot-wire anemometer

NASA Technical Reports Server (NTRS)

Watmuff, Jonathan H.

1994-01-01

A high-performance constant-temperature hot-wire anemometer has been designed based on a system theory analysis that can be extended to arbitrary order. A motivating factor behind the design was to achieve the highest possible frequency response while ensuring overall system stability. Based on these considerations, the design of the circuit and the selection of components is discussed in depth. Basic operating instructions are included in an operator's guide. The analysis is used to identify operating modes, observed in all anemometers, that are misleading in the sense that the operator can be deceived by interpreting an erroneous frequency response. Unlike other anemometers, this instrument provides front panel access to all the circuit parameters which affect system stability and frequency response. Instructions are given on how to identify and avoid these rather subtle and undesirable operating modes by appropriate adjustment of the controls. Details, such as fabrication drawings and a parts list, are provided to enable others to construct the instrument.

An investigation of rotor noise generation by aerodynamic disturbance. [aeroacoustic transfer functions

NASA Technical Reports Server (NTRS)

Whitfield, C. E.

1977-01-01

An open rotor was considered as a process for converting an unsteady velocity inflow into sound radiation. With the aid of crude assumptions, aero-acoustic transfer functions were defined theoretically for both discrete frequency and broad band noise. A study of the validity of these transfer functions yielded results which show good agreement at discrete frequencies though slightly less good for broad band noise. Agreement in both cases holds over three or more decades of the relevant parameters. A rotating hot wire anemometry system consisting of a single hot wire probe mounted in the nose cone of the rotor was used to quantify fluctuations in the airflow onto a single rotor blade for the transfer function results. Further theoretical analysis revealed that the sound field can be expressed in terms of blade-to-blade correlations in the airflow, and results from two probes rotating simultaneously were modelled mathematically and inserted in the theory. Preliminary results snow encouraging agreement with experimental data.

Mean velocities and Reynolds stresses upstream of a simulated wing-fuselage juncture

NASA Technical Reports Server (NTRS)

Mcmahon, H.; Hubbartt, J.; Kubendran, L. R.

1983-01-01

Values of three mean velocity components and six turbulence stresses measured in a turbulent shear layer upstream of a simulated wing-fuselage juncture and immediately downstream of the start of the juncture are presented nd discussed. Two single-sensor hot-wire probes were used in the measurements. The separated region just upstream of the wing contains an area of reversed flow near the fuselage surface where the turbulence level is high. Outside of this area the flow skews as it passes around the body, and in this skewed region the magnitude and distribution of the turbulent normal and shear stresses within the shear layer are modified slightly by the skewing and deceleration of the flow. A short distance downstream of the wing leading edge the secondary flow vortext is tightly rolled up and redistributes both mean flow and turbulence in the juncture. The data acquisition technique employed here allows a hot wire to be used in a reversed flow region to indicate flow direction.

An investigation of the open-loop amplification of Reynolds number dependent processes by wave distortion

NASA Technical Reports Server (NTRS)

Purdy, K. R.; Ventrice, M. B.; Fang, J.

1972-01-01

Analytical and experimental studies were initiated to determine if the response of a constant temperature hot wire anemometer to acoustic oscillations could serve as an analog to the response of the drop vaporization burning rate process to acoustic oscillations, and, perhaps, also as an analog to any Reynolds number dependent process. The motivation behind this study was a recent analytical study which showed that distorted acoustic oscillations could amplify the open-loop response of vaporization limited combustion. This type of amplification may be the cause of unstable combustion in liquid propellant rocket engines. The analytical results obtained for the constant temperature anemometer are similar in nature to those previously obtained for vaporization limited combustion and indicate that the response is dependent on the amount and type of distortion as well as other factors, such as sound pressure level, Mach number and hot wire temperature. Preliminary results indicate qualitative agreement between theory and experiment.

Simultaneous Heat and Mass Transfer Model for Convective Drying of Building Material

NASA Astrophysics Data System (ADS)

Upadhyay, Ashwani; Chandramohan, V. P.

2018-04-01

A mathematical model of simultaneous heat and moisture transfer is developed for convective drying of building material. A rectangular brick is considered for sample object. Finite-difference method with semi-implicit scheme is used for solving the transient governing heat and mass transfer equation. Convective boundary condition is used, as the product is exposed in hot air. The heat and mass transfer equations are coupled through diffusion coefficient which is assumed as the function of temperature of the product. Set of algebraic equations are generated through space and time discretization. The discretized algebraic equations are solved by Gauss-Siedel method via iteration. Grid and time independent studies are performed for finding the optimum number of nodal points and time steps respectively. A MATLAB computer code is developed to solve the heat and mass transfer equations simultaneously. Transient heat and mass transfer simulations are performed to find the temperature and moisture distribution inside the brick.

Use of predissociation to enhance the atomic hydrogen ion fraction in ion sources

DOEpatents

Kim, Jinchoon

1979-01-01

A duopigatron ion source is modified by replacing the normal oxide-coated wire filament cathode of the ion source with a hot tungsten oven through which hydrogen gas is fed into the arc chamber. The hydrogen gas is predissociated in the hot oven prior to the arc discharge, and the recombination rate is minimized by hot walls inside of the arc chamber. With the use of the above modifications, the atomic H.sub.1.sup.+ ion fraction output can be increased from the normal 50% to greater than 70% with a corresponding decrease in the H.sub.2.sup.+ and H.sub.3.sup.+ molecular ion fraction outputs from the ion source.

Wire bonding quality monitoring via refining process of electrical signal from ultrasonic generator

NASA Astrophysics Data System (ADS)

Feng, Wuwei; Meng, Qingfeng; Xie, Youbo; Fan, Hong

2011-04-01

In this paper, a technique for on-line quality detection of ultrasonic wire bonding is developed. The electrical signals from the ultrasonic generator supply, namely, voltage and current, are picked up by a measuring circuit and transformed into digital signals by a data acquisition system. A new feature extraction method is presented to characterize the transient property of the electrical signals and further evaluate the bond quality. The method includes three steps. First, the captured voltage and current are filtered by digital bandpass filter banks to obtain the corresponding subband signals such as fundamental signal, second harmonic, and third harmonic. Second, each subband envelope is obtained using the Hilbert transform for further feature extraction. Third, the subband envelopes are, respectively, separated into three phases, namely, envelope rising, stable, and damping phases, to extract the tiny waveform changes. The different waveform features are extracted from each phase of these subband envelopes. The principal components analysis (PCA) method is used for the feature selection in order to remove the relevant information and reduce the dimension of original feature variables. Using the selected features as inputs, an artificial neural network (ANN) is constructed to identify the complex bond fault pattern. By analyzing experimental data with the proposed feature extraction method and neural network, the results demonstrate the advantages of the proposed feature extraction method and the constructed artificial neural network in detecting and identifying bond quality.

Energy Deposition and Condition of the Metal Core in Exploding Wire Experiments

NASA Astrophysics Data System (ADS)

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W.; McDaniel, D. H.; Waisman, E. M.; Sasorov, P. V.

2002-11-01

Measurements of the Joule energy deposition into exploding wire and its relation with condition of the expanding wire core are presented. Wires of nine different metals with diameters of 10-30 microns, have been exploded by fast 150A/ns and slow 20A/ns pulses, in vacuum and in air. It has been shown by interferometry and light emission that expanding wire core has different conditions. The substances with small atomization enthalpy (Ag, Al, Cu, Au) demonstrate full vaporization of the wire core. The refractory metals (Ti, Pt, Mo, W) demonstrates that core consists from vapor and small and hot microparticles. In this case we observe "firework effect" when large radiation from the wire exceed the energy deposition time in a three order of magnitude. For non-refractory metals radiation dropping fast in 100 ns time scale due to effective adiabatic cooling. It is possible if main part of the metal core was vaporized. The interferometrical investigation of the refraction coefficient of expanding metal core is proof this conclusion. It has been shown that energy deposition before surface breakdown dependent strongly from current rate, surface coatings, environment, wire diameter and radial electric field. The regime of wire explosion in vacuum without shunting plasma shell has been realized for fast exploding mode. In this case we observe anomaly high energy deposition in to the wire core exceeding regular value in almost 20 times. The experimental results for Al wire have been compared with ALEGRA 2D MHD simulations. *Sandia is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL8500.

Quick-disconnect harness system for helmet-mounted displays

NASA Astrophysics Data System (ADS)

Bapu, P. T.; Aulds, M. J.; Fuchs, Steven P.; McCormick, David M.

1992-10-01

We have designed a pilot's harness-mounted, high voltage quick-disconnect connectors with 62 pins, to transmit voltages up to 13.5 kV and video signals with 70 MHz bandwidth, for a binocular helmet-mounted display system. It connects and disconnects with power off, and disconnects 'hot' without pilot intervention and without producing external sparks or exposing hot embers to the explosive cockpit environment. We have implemented a procedure in which the high voltage pins disconnect inside a hermetically-sealed unit before the physical separation of the connector. The 'hot' separation triggers a crowbar circuit in the high voltage power supplies for additional protection. Conductor locations and shields are designed to reduce capacitance in the circuit and avoid crosstalk among adjacent circuits. The quick- disconnect connector and wiring harness are human-engineered to ensure pilot safety and mobility. The connector backshell is equipped with two hybrid video amplifiers to improve the clarity of the video signals. Shielded wires and coaxial cables are molded as a multi-layered ribbon for maximum flexibility between the pilot's harness and helmet. Stiff cabling is provided between the quick-disconnect connector and the aircraft console to control behavior during seat ejection. The components of the system have been successfully tested for safety, performance, ergonomic considerations, and reliability.

The MHOST finite element program: 3-D inelastic analysis methods for hot section components. Volume 1: Theoretical manual

NASA Technical Reports Server (NTRS)

Nakazawa, Shohei

1991-01-01

Formulations and algorithms implemented in the MHOST finite element program are discussed. The code uses a novel concept of the mixed iterative solution technique for the efficient 3-D computations of turbine engine hot section components. The general framework of variational formulation and solution algorithms are discussed which were derived from the mixed three field Hu-Washizu principle. This formulation enables the use of nodal interpolation for coordinates, displacements, strains, and stresses. Algorithmic description of the mixed iterative method includes variations for the quasi static, transient dynamic and buckling analyses. The global-local analysis procedure referred to as the subelement refinement is developed in the framework of the mixed iterative solution, of which the detail is presented. The numerically integrated isoparametric elements implemented in the framework is discussed. Methods to filter certain parts of strain and project the element discontinuous quantities to the nodes are developed for a family of linear elements. Integration algorithms are described for linear and nonlinear equations included in MHOST program.

Finite volume analysis of temperature effects induced by active MRI implants: 2. Defects on active MRI implants causing hot spots.

PubMed

Busch, Martin H J; Vollmann, Wolfgang; Grönemeyer, Dietrich H W

2006-05-26

Active magnetic resonance imaging implants, for example stents, stent grafts or vena cava filters, are constructed as wireless inductively coupled transmit and receive coils. They are built as a resonator tuned to the Larmor frequency of a magnetic resonance system. The resonator can be added to or incorporated within the implant. This technology can counteract the shielding caused by eddy currents inside the metallic implant structure. This may allow getting diagnostic information of the implant lumen (in stent stenosis or thrombosis for example). The electro magnetic rf-pulses during magnetic resonance imaging induce a current in the circuit path of the resonator. A by material fatigue provoked partial rupture of the circuit path or a broken wire with touching surfaces can set up a relatively high resistance on a very short distance, which may behave as a point-like power source, a hot spot, inside the body part the resonator is implanted to. This local power loss inside a small volume can reach (1/4) of the total power loss of the intact resonating circuit, which itself is proportional to the product of the resonator volume and the quality factor and depends as well from the orientation of the resonator with respect to the main magnetic field and the imaging sequence the resonator is exposed to. First an analytical solution of a hot spot for thermal equilibrium is described. This analytical solution with a definite hot spot power loss represents the worst case scenario for thermal equilibrium inside a homogeneous medium without cooling effects. Starting with this worst case assumptions additional conditions are considered in a numerical simulation, which are more realistic and may make the results less critical. The analytical solution as well as the numerical simulations use the experimental experience of the maximum hot spot power loss of implanted resonators with a definite volume during magnetic resonance imaging investigations. The finite volume analysis calculates the time developing temperature maps for the model of a broken linear metallic wire embedded in tissue. Half of the total hot spot power loss is assumed to diffuse into both wire parts at the location of a defect. The energy is distributed from there by heat conduction. Additionally the effect of blood perfusion and blood flow is respected in some simulations because the simultaneous appearance of all worst case conditions, especially the absence of blood perfusion and blood flow near the hot spot, is very unlikely for vessel implants. The analytical solution as worst case scenario as well as the finite volume analysis for near worst case situations show not negligible volumes with critical temperature increases for part of the modeled hot spot situations. MR investigations with a high rf-pulse density lasting below a minute can establish volumes of several cubic millimeters with temperature increases high enough to start cell destruction. Longer exposure times can involve volumes larger than 100 mm3. Even temperature increases in the range of thermal ablation are reached for substantial volumes. MR sequence exposure time and hot spot power loss are the primary factors influencing the volume with critical temperature increases. Wire radius, wire material as well as the physiological parameters blood perfusion and blood flow inside larger vessels reduce the volume with critical temperature increases, but do not exclude a volume with critical tissue heating for resonators with a large product of resonator volume and quality factor. The worst case scenario assumes thermal equilibrium for a hot spot embedded in homogeneous tissue without any cooling due to blood perfusion or flow. The finite volume analysis can calculate the results for near and not close to worst case conditions. For both cases a substantial volume can reach a critical temperature increase in a short time. The analytical solution, as absolute worst case, points out that resonators with a small product of inductance volume and quality factor (Q V(ind) < 2 cm3) are definitely save. Stents for coronary vessels or resonators used as tracking devices for interventional procedures therefore have no risk of high temperature increases. The finite volume analysis shows for sure that also conditions not close to the worst case reach physiologically critical temperature increases for implants with a large product of inductance volume and quality factor (Q V(ind) > 10 cm3). Such resonators exclude patients from exactly the MRI investigation these devices are made for.

A thermodynamic framework for understanding temperature sensing by transient receptor potential (TRP) channels

PubMed Central

Clapham, David E.; Miller, Christopher

2011-01-01

The exceptionally high temperature sensitivity of certain transient receptor potential (TRP) family ion channels is the molecular basis of hot and cold sensation in sensory neurons. The laws of thermodynamics dictate that opening of these specialized TRP channels must involve an unusually large conformational standard-state enthalpy, ΔHo: positive ΔHo for heat-activated and negative ΔHo for cold-activated TRPs. However, the molecular source of such high-enthalpy changes has eluded neurobiologists and biophysicists. Here we offer a general, unifying mechanism for both hot and cold activation that recalls long-appreciated principles of protein folding. We suggest that TRP channel gating is accompanied by large changes in molar heat capacity, ΔCP. This postulate, along with the laws of thermodynamics and independent of mechanistic detail, leads to the conclusion that hot- and cold-sensing TRPs operate by identical conformational changes. PMID:22109551

A thermodynamic framework for understanding temperature sensing by transient receptor potential (TRP) channels.

PubMed

Clapham, David E; Miller, Christopher

2011-12-06

The exceptionally high temperature sensitivity of certain transient receptor potential (TRP) family ion channels is the molecular basis of hot and cold sensation in sensory neurons. The laws of thermodynamics dictate that opening of these specialized TRP channels must involve an unusually large conformational standard-state enthalpy, ΔH(o): positive ΔH(o) for heat-activated and negative ΔH(o) for cold-activated TRPs. However, the molecular source of such high-enthalpy changes has eluded neurobiologists and biophysicists. Here we offer a general, unifying mechanism for both hot and cold activation that recalls long-appreciated principles of protein folding. We suggest that TRP channel gating is accompanied by large changes in molar heat capacity, ΔC(P). This postulate, along with the laws of thermodynamics and independent of mechanistic detail, leads to the conclusion that hot- and cold-sensing TRPs operate by identical conformational changes.

Near wakes of advanced turbopropellers

NASA Technical Reports Server (NTRS)

Hanson, D. B.; Patrick, W. P.

1989-01-01

The flow in the wake of a model single rotation Prop-Fan rotor operating in a wind tunnel was traversed with a hot-wire anemometer system designed to determine the 3 periodic velocity components. Special data acquisition and data reduction methods were required to deal with the high data frequency, narrow wakes, and large fluctuating air angles in the tip vortex region. The model tip helical Mach number was 1.17, simulating the cruise condition. Although the flow field is complex, flow features such as viscous velocity defects, vortex sheets, tip vortices, and propagating acoustic pulses are clearly identified with the aid of a simple analytical wake theory.

A Method of Estimating Low Turbulence Levels in Near Real Time Using Laser Anemometry

NASA Technical Reports Server (NTRS)

Goldman, Louis J.; Seasholtz, Richard G.

2004-01-01

Laser anemometry was used to make two independent measurements of the flow velocity by capturing individual Doppler signals with high-speed digitizing boards. The two independent measurements were cross-correlated to reduce the contribution of photo detector shot noise on the frequency determination and subsequently on the turbulence estimate. In addition, criteria were developed to eliminate "bad" Doppler bursts from the data set, which then allowed reasonable low turbulence estimates to be made. The laser anemometer measurements were obtained at the inlet of an annular cascade and at the exit of a flow calibration nozzle and were compared with hot-wire data.

Multiwire conductor having increased interwire resistance and good mechanical stability and method for making same

DOEpatents

Luhman, Thomas; Klamut, Carl

1984-02-14

An improved multiwire conductor of the type which is mechanically stabilized by a solder filler. A solder filled conductor is heated to a temperature sufficient to make the solder brittle, but below the melting point of the solder. While still hot, the conductor is flexed, causing the solder to separate from the wires comprising the conductor, thereby increasing the interwire resistance. In one embodiment the conductor may be heated to a temperature above the eutectic temperature of the solder so that a controlled amount of solder is removed. The subject invention is particularly suited for use with braided, ribbon-type, solder filled superconductors.

Multiwire conductor having increased interwire resistance and good mechanical stability and method for making same

DOEpatents

Luhman, T.; Klamut, C.

1982-03-15

An improved multiwire conductor of the type which is mechanically stabilized by a solder filler. A solder filled conductor is heated to a temperature sufficient to make the solder brittle, but below the melting point of the solder. While still hot, the conductor is flexed, causing the solder to separate from the wires comprising the conductor, thereby increasing the interwire resistance. In one embodiment the conductor may be heated to a temperature above the eutectic temperature of the solder so that a controlled amount of solder is removed. The subject invention is particularly suited for use with braided, ribbon-type, solder filled superconductors.

Summary of the CTS Transient Event Counter data after one year of operation. [Communication Technology Satellite

NASA Technical Reports Server (NTRS)

Stevens, N. J.; Klinect, V. W.; Gore, J. V.

1977-01-01

The environmental charging of satellite surfaces during geomagnetic substorms is the apparent cause of a significant number of anomalous events occurring on geosynchronous satellites since the early 1970's. Electromagnetic pulses produced in connection with the differential charging of insulators can couple into the spacecraft harness and cause electronic switching anomalies. An investigation conducted to determine the response of the spacecraft surfaces to substorm particle fluxes makes use of a harness transient detector. The harness transient detector, called the Transient Event Counter (TEC) was built and integrated into the Canadian-American Communications Technology Satellite (CTS). A description of the TEC and its operational characteristics is given and the obtained data are discussed. The data show that the satellite surfaces appear to be charged to the point that discharges occur and that the discharge-induced transients couple into the wire harnesses.

Ultrasonic Non Linearity Characterization of the Stainless Steel Wire Reinforced Aluminium Composite

NASA Astrophysics Data System (ADS)

Kim, C. S.; Park, T. S.; Park, I. K.; Hyun, C. Y.

2009-03-01

The effectiveness of the ultrasonic nonlinearity measurement for nearly closed cracks was demonstrated for hot pressing and extrusion of stainless steel 304 short wire reinforced aluminum composite. Aluminum based composites show considerable potential in the aerospace industry and the automotive industry due to their high specific strength and low thermal expansion coefficient. The ultrasonic nonlinearity (β/β0) increased with the volume fraction of SSF and aging heat treatment because of the generation of microvoids resulted from localized SSF and matrix precipitation. This study demonstrates the potential for characterization of reinforced composite materials fabricated by the powder metallurgy technique.

Effect of Wall Temperature on Roughness Induced Attachment-Line Transition

NASA Technical Reports Server (NTRS)

Dietz, Anthony; Coleman, Colin; Laub, Jim; Poll, D. I. A.; Nixon, David (Technical Monitor)

1999-01-01

An experiment on a cooled swept cylinder in a low-disturbance Mach 1.6 wind tunnel is described. The flow attachment line is disturbed by trip wires of varying size and the laminar/turbulent state of the downstream boundary layer is determined with a hot wire. The results demonstrate that although cooling the wall increases the stability of the boundary layer, it promotes roughness induced transition. Analysis of the data suggests that the attachment- line Reynolds number can account for the effect of wall cooling if the viscosity is evaluated at a particular reference temperature.

Turbulence measurements in axisymmetric jets of air and helium. I - Air jet. II - Helium jet

NASA Technical Reports Server (NTRS)

Panchapakesan, N. R.; Lumley, J. L.

1993-01-01

Results are presented of measurements on turbulent round jets of air and of helium of the same nozzle momentum efflux, using, for the air jets, x-wire hot-wire probes mounted on a moving shuttle and, for He jets, a composite probe consisting of an interference probe of the Way-Libby type and an x-probe. Current models for scalar triple moments were evaluated. It was found that the performance of the model termed the Full model, which includes all terms except advection, was very good for both the air and the He jets.

Air Force Academy Aeronautics Digest.

DTIC Science & Technology

1985-04-01

7964, 1964. 10. Dudzinski, J.T. and L.N. Krause , Flow Direction Measurement with Fixed-Position Probes, NASA TMX-1904, 1969. 11. Beecham, L.J. and...Bob Hatfield in instrumenting the hot-wire airfoil model and refurbishing the pitching mechanism, Mr Russ Me inzer and Mr. Wolfgang Bank of the

Hot spots of Io

NASA Technical Reports Server (NTRS)

Pearl, J. C.; Sinton, W. M.

1982-01-01

The size and temperature, morphology and distribution, variability, possible absorption features, and processes of hot spots on Io are discussed, and an estimate of the global heat flux is made. Size and temperature information is deconvolved to obtain equivalent radius and temperature of hot spots, and simultaneously obtained Voyager thermal and imaging data is used to match hot sources with specific geologic features. In addition to their thermal output, it is possible that hot spots are also characterized by production of various gases and particulate materials; the spectral signature of SO2 has been seen. Origins for relatively stable, low temperature sources, transient high temperature sources, and relatively stable, high-tmperature sources are discussed.

Progress in American Superconductor's HTS wire and optimization for fault current limiting systems

NASA Astrophysics Data System (ADS)

Malozemoff, Alexis P.

2016-11-01

American Superconductor has developed composite coated conductor tape-shaped wires using high temperature superconductor (HTS) on a flexible substrate with laminated metal stabilizer. Such wires enable many applications, each requiring specific optimization. For example, coils for HTS rotating machinery require increased current density J at 25-50 K. A collaboration with Argonne, Brookhaven and Los Alamos National Laboratories and several universities has increased J using an optimized combination of precipitates and ion irradiation defects in the HTS. Major commercial opportunities also exist to enhance electric power grid resiliency by linking substations with distribution-voltage HTS power cables [10]. Such links provide alternative power sources if one substation's transmission-voltage power is compromised. But they must also limit fault currents which would otherwise be increased by such distribution-level links. This can be done in an HTS cable, exploiting the superconductor-to-resistive transition when current exceeds the wires' critical J. A key insight is that such transitions are usually nonuniform; so the wire must be designed to prevent localized hot spots from damaging the wire or even generating gas bubbles in the cable causing dielectric breakdown. Analysis shows that local heating can be minimized by increasing the composite tape's total thickness, decreasing its total resistance in the normal state and decreasing its critical J. This conflicts with other desirable wire characteristics. Optimization of these conflicting requirements is discussed.

An Approach to the Lightning Overvoltage Protection of Medium Voltage Lines in Severe Lightning Areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Omidiora, M. A.; Lehtonen, M.

2008-05-08

This paper deals with the effect of shield wires on lightning overvoltage reduction and the energy relief of MOV (Metal Oxide Varistor) arresters from direct strokes to distribution lines. The subject of discussion is the enhancement of lightning protection in Finnish distribution networks where lightning is most severe. The true index of lightning severity in these areas is based on the ground flash densities and return stroke data collected from the Finnish meteorological institute. The presented test case is the IEEE 34-node test feeder injected with multiple lightning strokes and simulated with the Alternative Transients Program/Electromagnetic Transients program (ATP/EMTP). Themore » response of the distribution line to lightning strokes was modeled with three different cases: no protection, protection with surge arresters and protection with a combination of shield wire and arresters. Simulations were made to compare the resulting overvoltages on the line for all the analyzed cases.« less

A Galinstan-Filled Capillary Probe for Thermal Conductivity Measurements and Its Application to Molten Eutectic {KNO}_3-{NaNO}_3-{NO}_2 (HTS) up to 700 K

NASA Astrophysics Data System (ADS)

Le Brun, Niccolò; Markides, Christos N.

2015-11-01

The successful measurement of the thermal conductivity of molten salts is a challenging undertaking due to the electrically conducting and possibly also aggressive nature of the materials, as well as the elevated temperatures at which these data are required. For accurate and reproducible measurements, it is important to develop a suitable experimental apparatus and methodology. In this study, we explore a modified version of the transient hot-wire method, which employs a molten-metal-filled capillary in order to circumvent some of the issues encountered in previous studies. Specifically, by using a novel flexible U-shaped quartz-capillary, filled with a eutectic mixture of gallium, indium and tin, commercially known as Galinstan, we proceed to measure the thermal conductivity of molten eutectic {KNO}_3-{NaNO}_3-{NaNO}_2. The new probe is demonstrated as being able to measure the thermal conductivity of this molten salt, which is found to range from 0.48 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} at 500 K to 0.47 {W}{\\cdot }{m}^{-1}{\\cdot }{K}^{-1} at close to 700 K, with an overall expanded uncertainty (95 % confidence) of 3.1 %. The quartz is found to retain its electrically insulating properties and no current leakage is detected in the sample over the investigated temperature range. The thermal conductivity data reported in the present study are also used to elucidate a partial disagreement found in the literature for this material.

Experimental and Statistical Analysis of MgO Nanofluids for Thermal Enhancement in a Novel Flat Plate Heat Pipes

NASA Astrophysics Data System (ADS)

Pandiaraj, P.; Gnanavelbabu, A.; Saravanan, P.

Metallic fluids like CuO, Al2O3, ZnO, SiO2 and TiO2 nanofluids were widely used for the development of working fluids in flat plate heat pipes except magnesium oxide (MgO). So, we initiate our idea to use MgO nanofluids in flat plate heat pipe as a working fluid material. MgO nanopowders were synthesized by wet chemical method. Solid state characterizations of synthesized nanopowders were carried out by Ultraviolet Spectroscopy (UV), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) techniques. Synthesized nanopowders were prepared as nanofluids by adding water and as well as water/ethylene glycol as a binary mixture. Thermal conductivity measurements of prepared nanofluids were studied using transient hot-wire apparatus. Response surface methodology based on the Box-Behnken design was implemented to investigate the influence of temperature (30-60∘C), particle fraction (1.5-4.5 vol.%), and solution pH (4-12) of nanofluids as the independent variables. A total of 17 experiments were accomplished for the construction of second-order polynomial equations for target output. All the influential factors, their mutual effects and their quadratic terms were statistically validated by analysis of variance (ANOVA). The optimum stability and thermal conductivity of MgO nanofluids with various temperature, volume fraction and solution pH were predicted and compared with experimental results. The results revealed that increase in particle fraction and pH of MgO nanofluids at certain points would increase thermal conductivity and become stable at nominal temperature.

Thermal conductivity of the cryoprotective cocktail DP6 in cryogenic temperatures, in the presence and absence of synthetic ice modulators

PubMed Central

Ehrlich, Lili E.; Malen, Jonathan A.; Rabin, Yoed

2016-01-01

The thermal conductivity of the cryoprotective agent (CPA) cocktail DP6 in combination with synthetic ice modulators (SIMs) is measured in this study, using a transient hot-wire method. DP6 is a mixture of 3M dimethyl sulfoxide (DMSO) and 3M propylene glycol, which received significant attention in the cryobiology community in recent years. Tested SIMs include 6% 1,3Cyclohexanediol, 6% 2,3Butanediol, and 12% PEG400 (percentage by volume). This study integrates the scanning cryomacroscope for visual verification of crystallization and vitrification events. It is demonstrated that the thermal conductivity of the vitrifying CPA cocktail decreases monotonically with the decreasing temperature down to −180°C. By contrast, the thermal conductivity of the crystalline material increases with decreasing temperature in the same temperature range. Results of this study demonstrate that the thermal conductivity may vary by three fold between the amorphous and crystalline phases of DP6 below the glass transition temperature of DP6 (Tg = −119°C). The selected SIMs demonstrate the ability to inhibit crystallization in DP6, even at subcritical cooling rates. An additional ice suppression capability is observed by the Euro-Collins as a vehicle solution, disproportionate to its volume ratio in the cocktail. The implication of the observed thermal conductivity differences between the amorphous and crystalline phases of the same cocktail on cryopreservation simulations is significant in some cases and must be taken into account in thermal analyses of cryopreservation protocols. PMID:27471057

Thermal conductivity of the cryoprotective cocktail DP6 in cryogenic temperatures, in the presence and absence of synthetic ice modulators.

PubMed

Ehrlich, Lili E; Malen, Jonathan A; Rabin, Yoed

2016-10-01

The thermal conductivity of the cryoprotective agent (CPA) cocktail DP6 in combination with synthetic ice modulators (SIMs) is measured in this study, using a transient hot-wire method. DP6 is a mixture of 3 M dimethyl sulfoxide (DMSO) and 3 M propylene glycol, which received significant attention in the cryobiology community in recent years. Tested SIMs include 6% 1,3Cyclohexanediol, 6% 2,3Butanediol, and 12% PEG400 (percentage by volume). This study integrates the scanning cryomacroscope for visual verification of crystallization and vitrification events. It is demonstrated that the thermal conductivity of the vitrifying CPA cocktail decreases monotonically with the decreasing temperature down to -180 °C. By contrast, the thermal conductivity of the crystalline material increases with decreasing temperature in the same temperature range. Results of this study demonstrate that the thermal conductivity may vary by three fold between the amorphous and crystalline phases of DP6 below the glass transition temperature of DP6 (Tg = -119 °C). The selected SIMs demonstrate the ability to inhibit crystallization in DP6, even at subcritical cooling rates. An additional ice suppression capability is observed by the Euro-Collins as a vehicle solution, disproportionate to its volume ratio in the cocktail. The implication of the observed thermal conductivity differences between the amorphous and crystalline phases of the same cocktail on cryopreservation simulations is significant in some cases and must be taken into account in thermal analyses of cryopreservation protocols. Copyright © 2016. Published by Elsevier Inc.

Testing experience with unheated stain-gage balances in the NTF. [National Transonic Facility

NASA Technical Reports Server (NTRS)

Jacobs, Peter F.; Ferris, Alice T.

1986-01-01

A series of cryogenic (cryo) cycles was conducted in the cryo chamber at the National Transonic Facility (NTF) in order to identify the cause of apparent strain shifts in axial force with temperature for the Pathfinder I model and to minimize their effects. The results of the investigation indicated that the major cause of axial force end point shifts and thermal hysteresis loops was the thickness of the Teflon insulation on the instrumentation wires crossing the balance. By reducing the thickness of the insulation and the total number and size of the wires, apparent strain values were achieved for the model with instrumentation wires which were nearly identical to those for the model without wires. Because of the special design features used, the balance output was very accurate and repeatable over the entire NTF temperature range, even with balance thermal gradients as large as 64 F and transient conditions as large as 3 F/minute.

Validation of a Computational Model for the SLS Core Stage Oxygen Tank Diffuser Concept and the Low Profile Diffuser - An Advanced Development Design for the SLS

NASA Technical Reports Server (NTRS)

Brodnick, Jacob; Richardson, Brian; Ramachandran, Narayanan

2015-01-01

The Low Profile Diffuser (LPD) project originated as an award from the Marshall Space Flight Center (MSFC) Advanced Development (ADO) office to the Main Propulsion Systems Branch (ER22). The task was created to develop and test an LPD concept that could produce comparable performance to a larger, traditionally designed, ullage gas diffuser while occupying a smaller volume envelope. Historically, ullage gas diffusers have been large, bulky devices that occupy a significant portion of the propellant tank, decreasing the tank volume available for propellant. Ullage pressurization of spacecraft propellant tanks is required to prevent boil-off of cryogenic propellants and to provide a positive pressure for propellant extraction. To achieve this, ullage gas diffusers must slow hot, high-pressure gas entering a propellant tank from supersonic speeds to only a few meters per second. Decreasing the incoming gas velocity is typically accomplished through expansion to larger areas within the diffuser which has traditionally led to large diffuser lengths. The Fluid Dynamics Branch (ER42) developed and applied advanced Computational Fluid Dynamics (CFD) analysis methods in order to mature the LPD design from and initial concept to an optimized test prototype and to provide extremely accurate pre-test predictions of diffuser performance. Additionally, the diffuser concept for the Core Stage of the Space Launch System (SLS) was analyzed in a short amount of time to guide test data collection efforts of the qualification of the device. CFD analysis of the SLS diffuser design provided new insights into the functioning of the device and was qualitatively validated against hot wire anemometry of the exterior flow field. Rigorous data analysis of the measurements was performed on static and dynamic pressure data, data from two microphones, accelerometers and hot wire anemometry with automated traverse. Feasibility of the LPD concept and validation of the computational model were demonstrated by the test data.

Development of a Novel Method for the Exploration of the Thermal Response of Superfluid Helium Cooled Superconducting Cables to Pulse Heat Loads

NASA Astrophysics Data System (ADS)

Winkler, T.; Koettig, T.; van Weelderen, R.; Bremer, J.; ter Brake, H. J. M.

Management of transient heat deposition in superconducting magnets and its extraction from the aforementioned is becoming increasingly important to bring high energy particle accelerator performance to higher beam energies and intensities. Precise knowledge of transient heat deposition phenomena in the magnet cables will permit to push the operation of these magnets as close as possible to their current sharing limit, without unduly provoking magnet quenches. With the prospect of operating the Large Hadron Collider at CERN at higher beam energies and intensities an investigation into the response to transient heat loads of LHC magnets, operating in pressurized superfluid helium, is being performed. The more frequently used approach mimics the cable geometry by resistive wires and uses Joule-heating to deposit energy. Instead, to approximate as closely as possible the real magnet conditions, a novel method for depositing heat in cable stacks made out of superconducting magnet-cables has been developed. The goal is to measure the temperature difference as a function of time between the cable stack and the superfluid helium bath depending on heat load and heat pulse length. The heat generation in the superconducting cable and precise measurement of small temperature differences are major challenges. The functional principle and experimental set-up are presented together with proof of principle measurements.

An experimental study of the noise generating mechanisms in supersonic jets

NASA Technical Reports Server (NTRS)

Mclaughlin, D. K.

1979-01-01

Flow fluctuation measurements with normal and X-wire hot-wire probes and acoustic measurements with a traversing condenser microphone were carried out in small air jets in the Mach number range from M = 0.9 to 2.5. One of the most successful studies involved a moderate Reynolds number M = 2.1 jet. The large scale turbulence properties in the jet, and the noise radiation were characterized. A parallel study involved similar measurements on a low Reynolds number M = 0.9 jet. These measurements show that there are important differences in the noise generation process of the M = 0.9 jet in comparison with low supersonic Mach number (M = 1.4) jets. Problems encounted while performing X-wire measurements in low Reynolds number jets of M = 2.1 and 2.5, and in installing a vacuum pump are discussed.

Flow Dynamics In Eccentrically Rotating Flasks Used For Dispersant Effectiveness Testing

EPA Science Inventory

The evaluation of dispersant effectiveness used for oil spills is commonly done using tests conducted in laboratory flasks. We used a Hot Wire Anemometer (HWA) to characterize mixing dynamics in the Swirling Flask (SF) and the Baffled Flask (BF), the latter is being considered b...

EVALUATION OF MIXING ENERGY IN LABORATORY FLASKS USED FOR DISPERSANT EFFECTIVENESS TESTING

EPA Science Inventory

The evaluation of dispersant effectiveness used for oil spills is commonly done using tests conducted in laboratory flasks. The success of a test relies on replication of the conditions at sea. We used a hot wire anemometer to characterize the turbulence characteristics in the s...

The rise and fall of a human recombination hot spot.

PubMed

Jeffreys, Alec J; Neumann, Rita

2009-05-01

Human meiotic crossovers mainly cluster into narrow hot spots that profoundly influence patterns of haplotype diversity and that may also affect genome instability and sequence evolution. Hot spots also seem to be ephemeral, but processes of hot-spot activation and their subsequent evolutionary dynamics remain unknown. We now analyze the life cycle of a recombination hot spot. Sperm typing revealed a polymorphic hot spot that was activated in cis by a single base change, providing evidence for a primary sequence determinant necessary, though not sufficient, to activate recombination. This activating mutation occurred roughly 70,000 y ago and has persisted to the present, most likely fortuitously through genetic drift despite its systematic elimination by biased gene conversion. Nonetheless, this self-destructive conversion will eventually lead to hot-spot extinction. These findings define a subclass of highly transient hot spots and highlight the importance of understanding hot-spot turnover and how it influences haplotype diversity.

Solar hot water system installed at Day's Inn Motel, Savannah, Georgia

NASA Technical Reports Server (NTRS)

1980-01-01

The Solar System was designed to provide 50 percent of the total Domestic Hot Water (DHW) demand. Liquid Flat Plate Collectors (900 square feet) are used for the collector subsystem. The collector subsystem is closed loop, using 50 percent Ethylene Glycol solution antifreeze for freeze protection. The 1,000 gallon fiber glass storage tank contains two heat exchangers. One of the heat exchangers heats the storage tank with the collector solar energy. The other heat exchanger preheats the cold supply water as it passes through on the way to the Domestic Hot Water (DHW) tank heaters. Electrical energy supplements the solar energy for the DHW. The Collector Mounting System utilizes guy wires to structurally tie the collector array to the building.

Early Fault Diagnosis of Bearings Using an Improved Spectral Kurtosis by Maximum Correlated Kurtosis Deconvolution

PubMed Central

Jia, Feng; Lei, Yaguo; Shan, Hongkai; Lin, Jing

2015-01-01

The early fault characteristics of rolling element bearings carried by vibration signals are quite weak because the signals are generally masked by heavy background noise. To extract the weak fault characteristics of bearings from the signals, an improved spectral kurtosis (SK) method is proposed based on maximum correlated kurtosis deconvolution (MCKD). The proposed method combines the ability of MCKD in indicating the periodic fault transients and the ability of SK in locating these transients in the frequency domain. A simulation signal overwhelmed by heavy noise is used to demonstrate the effectiveness of the proposed method. The results show that MCKD is beneficial to clarify the periodic impulse components of the bearing signals, and the method is able to detect the resonant frequency band of the signal and extract its fault characteristic frequency. Through analyzing actual vibration signals collected from wind turbines and hot strip rolling mills, we confirm that by using the proposed method, it is possible to extract fault characteristics and diagnose early faults of rolling element bearings. Based on the comparisons with the SK method, it is verified that the proposed method is more suitable to diagnose early faults of rolling element bearings. PMID:26610501

Thermal conductivity of catalyst layer of polymer electrolyte membrane fuel cells: Part 1 - Experimental study

NASA Astrophysics Data System (ADS)

Ahadi, Mohammad; Tam, Mickey; Saha, Madhu S.; Stumper, Jürgen; Bahrami, Majid

2017-06-01

In this work, a new methodology is proposed for measuring the through-plane thermal conductivity of catalyst layers (CLs) in polymer electrolyte membrane fuel cells. The proposed methodology is based on deconvolution of bulk thermal conductivity of a CL from measurements of two thicknesses of the CL, where the CLs are sandwiched in a stack made of two catalyst-coated substrates. Effects of hot-pressing, compression, measurement method, and substrate on the through-plane thermal conductivity of the CL are studied. For this purpose, different thicknesses of catalyst are coated on ethylene tetrafluoroethylene (ETFE) and aluminum (Al) substrates by a conventional Mayer bar coater and measured by scanning electron microscopy (SEM). The through-plane thermal conductivity of the CLs is measured by the well-known guarded heat flow (GHF) method as well as a recently developed transient plane source (TPS) method for thin films which modifies the original TPS thin film method. Measurements show that none of the studied factors has any effect on the through-plane thermal conductivity of the CL. GHF measurements of a non-hot-pressed CL on Al yield thermal conductivity of 0.214 ± 0.005 Wṡm-1ṡK-1, and TPS measurements of a hot-pressed CL on ETFE yield thermal conductivity of 0.218 ± 0.005 Wṡm-1ṡK-1.

Magnon-drag thermopile.

PubMed

Costache, Marius V; Bridoux, German; Neumann, Ingmar; Valenzuela, Sergio O

2011-12-18

Thermoelectric effects in spintronics are gathering increasing attention as a means of managing heat in nanoscale structures and of controlling spin information by using heat flow. Thermal magnons (spin-wave quanta) are expected to play a major role; however, little is known about the underlying physical mechanisms involved. The reason is the lack of information about magnon interactions and of reliable methods to obtain it, in particular for electrical conductors because of the intricate influence of electrons. Here, we demonstrate a conceptually new device that enables us to gather information on magnon-electron scattering and magnon-drag effects. The device resembles a thermopile formed by a large number of pairs of ferromagnetic wires placed between a hot and a cold source and connected thermally in parallel and electrically in series. By controlling the relative orientation of the magnetization in pairs of wires, the magnon drag can be studied independently of the electron and phonon-drag thermoelectric effects. Measurements as a function of temperature reveal the effect on magnon drag following a variation of magnon and phonon populations. This information is crucial to understand the physics of electron-magnon interactions, magnon dynamics and thermal spin transport.

Measurement of Thermal Conductivities of Two Cryoprotective Agent Solutions for Vitreous Cryopreservation of Organs at the Temperature Range of 77 K-300 K Using a Thermal Sensor Made of Microscale Enamel Copper Wire.

PubMed

Li, Yufang; Zhao, Gang; Hossain, S M Chapal; Panhwar, Fazil; Sun, Wenyu; Kong, Fei; Zang, Chuanbao; Jiang, Zhendong

2017-06-01

Biobanking of organs by cryopreservation is an enabling technology for organ transplantation. Compared with the conventional slow freezing method, vitreous cryopreservation has been regarded to be a more promising approach for long-term storage of organs. The major challenges to vitrification are devitrification and recrystallization during the warming process, and high concentrations of cryoprotective agents (CPAs) induced metabolic and osmotic injuries. For a theoretical model based optimization of vitrification, thermal properties of CPA solutions are indispensable. In this study, the thermal conductivities of M22 and vitrification solution containing ethylene glycol and dimethyl sulfoxide (two commonly used vitrification solutions) were measured using a self-made microscaled hot probe with enameled copper wire at the temperature range of 77 K-300 K. The data obtained by this study will further enrich knowledge of the thermal properties for CPA solutions at low temperatures, as is of primary importance for optimization of vitrification.

Cross-Beam Laser Joining of AA 6111 to Galvanized Steel in a Coach Peel Configuration

NASA Astrophysics Data System (ADS)

Yang, Guang; Mohammadpour, Masoud; Yazdian, Nima; Ma, Junjie; Carlson, Blair; Wang, Hui-Ping; Kovacevic, Radovan

2017-06-01

Cross-beam laser joining of aluminum alloy 6111 to hot-dip galvanized steel in the coach-peel configuration was investigated with the addition of AA 4047 filler wire. The filler material was not only brazed onto the galvanized steel but also partially fusion-welded with the aluminum panel. Through adjusting the laser power to 3.4 kW, a desirable wetting and spreading of filler wire on both panel surfaces could be achieved, and the thickness of intermetallic layer in the middle section of the interface between the weld bead and steel was less than 2 μm. To better understand the solid/liquid interfacial reaction at the brazing interface, two rotary Gaussian heat source models were introduced to simulate the temperature distribution in the molten pool by using the finite element method. Joint properties were examined in terms of microstructure and mechanical properties. During the tensile test, the fracture of coupons took place at the aluminum side rather than along the interface between the intermetallic layer and steel panel. No failure occurred during the three-point bending test.

Wakes of lifting and non-lifting bodies: 1. Instabilities & turbulence in the wake of a delta wing. 2. Control of three-dimensional phase dynamics in the wake of a cylinder

NASA Astrophysics Data System (ADS)

Miller, Gregory Dennis

1997-06-01

In the first part of this work, we study the instabilities and turbulent structures in the wake of a delta wing, using extensive flow visualization, hot wire anemometry, and DPIV. We employ a novel free-flight technique in water, coupled with an image processing technique, to study the evolution of the long-wavelength instability of the primary vortex pair. Although secondary vortical structures have received little attention to date, we find that the 'braid wake' vorticity between the vortex pair imposes small lengthscale turbulence around the principal vortices, as well as influence the development of a 'curtain' of vorticity left far above the descending vortex pair. We study the long-wavelength instability of the trailing vortex pair by measuring growth rate and wavelength of the instability directly, and we also measure all of the critical parameters of the vortices (i.e. vortex core radius, vorticity distribution, axial velocity distribution, spacing and circulation), which provide what appears to be the first complete comparison to the theory describing the instability. We find excellent agreement between measured and theoretical growth rates and wavelengths. In the second part of the work, we have devised a method to control the spanwise end conditions and patterns in the wake of a cylinder using 'end suction', which is both continuously-variable and admits transient control. Classical steady-state patterns, such as parallel or oblique shedding, or the 'chevron' patterns, are simply induced. The wake, at a given Reynolds number (Re), is receptive to a continuous range of oblique shedding angles (θ), rather than to discrete angles, and there is excellent agreement with the 'cos θ' formula for oblique-shedding frequencies. We show that the laminar shedding regime exists up to Re of 194, and that the immense disparity among reported critical Re for wake transition (Re = 140-190) can be explained in terms of spanwise end contamination. Our transient experiments have resulted in the discovery of new phenomena such as 'phase shocks' and 'phase expansions', which have excellent agreement with predictions from a Ginzburg- Landau wake model (collaboration with Peter Monkewitz, Lausanne).

A fundamental study of suction for Laminar Flow Control (LFC)

NASA Astrophysics Data System (ADS)

Watmuff, Jonathan H.

1992-10-01

This report covers the period forming the first year of the project. The aim is to experimentally investigate the effects of suction as a technique for Laminar Flow Control. Experiments are to be performed which require substantial modifications to be made to the experimental facility. Considerable effort has been spent developing new high performance constant temperature hot-wire anemometers for general purpose use in the Fluid Mechanics Laboratory. Twenty instruments have been delivered. An important feature of the facility is that it is totally automated under computer control. Unprecedently large quantities of data can be acquired and the results examined using the visualization tools developed specifically for studying the results of numerical simulations on graphics works stations. The experiment must be run for periods of up to a month at a time since the data is collected on a point-by-point basis. Several techniques were implemented to reduce the experimental run-time by a significant factor. Extra probes have been constructed and modifications have been made to the traverse hardware and to the real-time experimental code to enable multiple probes to be used. This will reduce the experimental run-time by the appropriate factor. Hot-wire calibration drift has been a frustrating problem owing to the large range of ambient temperatures experienced in the laboratory. The solution has been to repeat the calibrations at frequent intervals. However the calibration process has consumed up to 40 percent of the run-time. A new method of correcting the drift is very nearly finalized and when implemented it will also lead to a significant reduction in the experimental run-time.

A fundamental study of suction for Laminar Flow Control (LFC)

NASA Technical Reports Server (NTRS)

Watmuff, Jonathan H.

1992-01-01

This report covers the period forming the first year of the project. The aim is to experimentally investigate the effects of suction as a technique for Laminar Flow Control. Experiments are to be performed which require substantial modifications to be made to the experimental facility. Considerable effort has been spent developing new high performance constant temperature hot-wire anemometers for general purpose use in the Fluid Mechanics Laboratory. Twenty instruments have been delivered. An important feature of the facility is that it is totally automated under computer control. Unprecedently large quantities of data can be acquired and the results examined using the visualization tools developed specifically for studying the results of numerical simulations on graphics works stations. The experiment must be run for periods of up to a month at a time since the data is collected on a point-by-point basis. Several techniques were implemented to reduce the experimental run-time by a significant factor. Extra probes have been constructed and modifications have been made to the traverse hardware and to the real-time experimental code to enable multiple probes to be used. This will reduce the experimental run-time by the appropriate factor. Hot-wire calibration drift has been a frustrating problem owing to the large range of ambient temperatures experienced in the laboratory. The solution has been to repeat the calibrations at frequent intervals. However the calibration process has consumed up to 40 percent of the run-time. A new method of correcting the drift is very nearly finalized and when implemented it will also lead to a significant reduction in the experimental run-time.

Airflow Measurement of the Car HVAC Unit Using Hot-wire Anemometry

NASA Astrophysics Data System (ADS)

Fojtlín, Miloš; Planka, Michal; Fišer, Jan; Pokorný, Jan; Jícha, Miroslav

2016-03-01

Thermal environment in a vehicular cabin significantly influence drivers' fatigue and passengers' thermal comfort. This environment is traditionally managed by HVAC cabin system that distributes air and modifies its properties. In order to simulate cabin thermal behaviour, amount of the air led through car vents must be determined. The aim of this study was to develop methodology to measure airflow from the vents, and consequently calculate corresponding air distribution coefficients. Three climatic cases were selected to match European winter, summer, and spring / fall conditions. Experiments were conducted on a test vehicle in a climatic chamber. The car HVAC system was set to automatic control mode, and the measurements were executed after the system stabilisation—each case was independently measured three times. To be able to evaluate precision of the method, the airflow was determined at the system inlet (HVAC suction) and outlet (each vent), and the total airflow values were compared. The airflow was calculated by determining a mean value of the air velocity multiplied by an area of inlet / outlet cross-section. Hot-wire anemometry was involved to measure the air velocity. Regarding the summer case, total airflow entering the cabin was around 57 l s-1 with 60 % of the air entering the cabin through dashboard vents; no air was supplied to the feet compartment. The remaining cases had the same total airflow of around 42 l s-1, and the air distribution was focused mainly on feet and windows. The inlet and outlet airflow values show a good match with a maximum mass differential of 8.3 %.

Demonstration of radiation pulse shaping with nested-tungsten-wire-array pinches for high-yield inertial confinement fusion.

PubMed

Cuneo, M E; Vesey, R A; Sinars, D B; Chittenden, J P; Waisman, E M; Lemke, R W; Lebedev, S V; Bliss, D E; Stygar, W A; Porter, J L; Schroen, D G; Mazarakis, M G; Chandler, G A; Mehlhorn, T A

2005-10-28

Nested wire-array pinches are shown to generate soft x-ray radiation pulse shapes required for three-shock isentropic compression and hot-spot ignition of high-yield inertial confinement fusion capsules. We demonstrate a reproducible and tunable foot pulse (first shock) produced by interaction of the outer and inner arrays. A first-step pulse (second shock) is produced by inner array collision with a central CH2 foam target. Stagnation of the inner array at the axis produces the third shock. Capsules optimized for several of these shapes produce 290-900 MJ fusion yields in 1D simulations.

Measurements of the turbulent transport of heat and momentum in convexly curved boundary layers - Effects of curvature, recovery and free-stream turbulence

NASA Technical Reports Server (NTRS)

Kim, J.; Simon, T. W.

1987-01-01

The effects of streamwise convex curvature, recovery, and freestream turbulence intensity on the turbulent transport of heat and momentum in a mature boundary layer are studied using a specially designed three-wire hot-wire probe. Increased freestream turbulence is found to increase the profiles throughout the boundary layer on the flat developing wall. Curvature effects were found to dominate turbulence intensity effects for the present cases considered. For the higher TI (turbulence intensity) case, negative values of the turbulent Prandtl number are found in the outer half of the boundary layer, indicating a breakdown in Reynolds analogy.

Turbulence stress measurements in a nonadiabatic hypersonic boundary layer

NASA Technical Reports Server (NTRS)

Mikulla, V.; Horstman, C. C.

1975-01-01

Turbulent shear stress and direct turbulent total heat-flux measurements have been made across a nonadiabatic, zero pressure gradient, hypersonic boundary layer by using specially designed hot-wire probes free of strain-gauging and wire oscillation. Heat-flux measurements were in reasonably good agreement with values obtained by integrating the energy equation using measured profiles of velocity and temperature. The shear-stress values deduced from the measurements, by assuming zero correlation of velocity and pressure fluctuations, were lower than the values obtained by integrating the momentum equation. Statistical properties of the cross-correlations are similar to corresponding incompressible measurements at approximately the same momentum-thickness Reynolds number.

Deformability of Oxide Inclusions in Tire Cord Steels

NASA Astrophysics Data System (ADS)

Zhang, Lifeng; Guo, Changbo; Yang, Wen; Ren, Ying; Ling, Haitao

2018-04-01

The deformation of oxide inclusions in tire cord steels during hot rolling was analyzed, and the factors influencing their deformability at high and low temperatures were evaluated and discussed. The aspect ratio of oxide inclusions decreased with the increasing reduction ratio of the steel during hot rolling owing to the fracture of the inclusions. The aspect ratio obtained after the first hot-rolling process was used to characterize the high-temperature deformability of the inclusions. The deformation first increased and then decreased with the increasing (MgO + Al2O3)/(SiO2 + MnO) ratio of the inclusions. It also increased with the decreasing melting temperatures of the inclusions. Young's modulus was used to evaluate the low-temperature deformability of the inclusions. An empirical formula was fitted to calculate the Young's moduli of the oxides using the mean atomic volume. The moduli values of the inclusions causing wire fracture were significantly greater than the average. To reduce fracture in tire cord steel wires during cold drawing, it is proposed that inclusions be controlled to those with high SiO2 content and extremely low Al2O3 content. This proposal is based on the hypothesis that the deformabilities of oxides during cold drawing are inversely proportional to their Young's moduli. The future study thus proposed includes an experimental confirmation for the abovementioned predictions.

SUPRACONDYLAR FRACTURE OF THE HUMERUS IN CHILDREN: FIXATION WITH TWO CROSSED KIRSCHNER WIRES

PubMed Central

Carvalho, Roni Azevedo; Filho, Nelson Franco; Neto, Antonio Batalha Castello; Reis, Giulyano Dias; Dias, Marcos Pereira

2015-01-01

Objective: To analyze and present the surgical results from unstable supracondylar fractures of the humerus in children, treated by means of reduction and percutaneous fixation using two crossed Kirschner wires. Methods: A cross-sectional study was conducted on 20 children, taking into consideration sex, age at the time of the fracture, age at the time of the assessment, side affected, type and mechanism of trauma, postoperative complications and radiographic and clinic variables. Results: Ten fractures were observed in the left arm and ten in the right arm. The age at the time of the fracture ranged from 2 to 13 years (mean: 5.9 ± 2.48 years). Three fractures were classified as type II and 17 as type III. The length of follow-up ranged from four months to three years. Baumann's angle ranged from 69 to 100 (mean: 78.3) and cubitus varus was observed in four patients (values ranging from 84 to 100). According to the modified Flynn's criteria, 20 cases presented satisfactory outcomes: 17 excellent (85%), two good (10%) and one regular (5%). Two patients presented limited range of motion, two had paresthesia in the cubital region and one had transient neuropraxia of the ulnar nerve for six weeks. Conclusion: Percutaneous fixation with two crossed Kirschner wires leads to good results when carried out under direct viewing and with isolation of the ulnar nerve. PMID:27047887

Transient fields produced by a cylindrical electron beam flowing through a plasma

NASA Astrophysics Data System (ADS)

Firpo, Marie-Christine

2012-10-01

Fast ignition schemes (FIS) for inertial confinement fusion should involve in their final stage the interaction of an ignition beam composed of MeV electrons laser generated at the critical density surface with a dense plasma target. In this study, the out-of-equilibrium situation in which an initially sharp-edged cylindrical electron beam, that could e.g. model electrons flowing within a wire [1], is injected into a plasma is considered. A detailed computation of the subsequently produced magnetic field is presented [2]. The control parameter of the problem is shown to be the ratio of the beam radius to the electron skin depth. Two alternative ways to address analytically the problem are considered: one uses the usual Laplace transform approach, the other one involves Riemann's method in which causality conditions manifest through some integrals of triple products of Bessel functions.[4pt] [1] J.S. Green et al., Surface heating of wire plasmas using laser-irradiated cone geometries, Nature Physics 3, 853--856 (2007).[0pt] [2] M.-C. Firpo, http://hal.archives-ouvertes.fr/hal-00695629, to be published (2012).

Handbook of Supersonic Aerodynamics. Section 20. Wind Tunnel Instrumentation and Operation

DTIC Science & Technology

1961-01-01

colored Wratten gelatin filters are mounted in a suitable holder with the sides of the strips parallel and close enough to prevent light from passing...Knoblork, F. D., "A Hot-Wire Anemometer Developed for Full-Scale 0 Airship Measurements," The Daniel Guggenheim Airship Inst., pp. 58-61, 1935. 619

40 CFR 1065.245 - Sample flow meter for batch sampling.

Code of Federal Regulations, 2010 CFR

2010-07-01

... rates or total flow sampled into a batch sampling system over a test interval. You may use the... rates or total raw exhaust flow over a test interval. (b) Component requirements. We recommend that you... averaging Pitot tube, or a hot-wire anemometer. Note that your overall system for measuring sample flow must...

Air pollution from aircraft. [jet exhaust - aircraft fuels/combustion efficiency

NASA Technical Reports Server (NTRS)

Heywood, J. B.; Chigier, N. A.

1975-01-01

A model which predicts nitric oxide and carbon monoxide emissions from a swirl can modular combustor is discussed. A detailed analysis of the turbulent fuel-air mixing process in the swirl can module wake region is reviewed. Hot wire anemometry was employed, and gas sampling analysis of fuel combustion emissions were performed.

A possible reinterpretation of the Princeton superpipe data

NASA Astrophysics Data System (ADS)

Perry, A. E.; Hafez, S.; Chong, M. S.

2001-07-01

In experiments recently performed at Melbourne, Pitot-tube mean velocity profiles in a boundary layer disagreed with those obtained with hot wires. The standard MacMillan (1956) correction for the probe displacement effect and a correction for turbulence intensity were both required for obtaining agreement between the two sets of mean velocity data. We were thus motivated to reanalyse the Princeton superpipe data using the same two corrections. The result is a plausible conclusion that the superpipe is rough at the higher Reynolds numbers and its data follow the Colebrook (1939) formula for commercial pipes rather well. It also appears that the logarithmic law of the wall is valid, with a Kármán constant close to that found recently by Österlund (1999) from boundary layer measurements with a hot wire. The smooth regime in the pipe gave almost the same additive constant for the log-law as Österlund's. A comparison between the superpipe data and the pipe data of Perry, Henbest & Chong (1997) suggests that the conventional velocity defect law may be valid down to lower Reynolds numbers than concluded by Zagarola & Smits (1998).

A flying hot wire study of the turbulent near wake of a circular cylinder at Reynolds number of 140,000. Ph.D. Thesis. Progress Report

NASA Technical Reports Server (NTRS)

Cantwell, B. J.

1975-01-01

The phenomenology was studied of the processes of vortex formation and transport in the near wake, at a Reynolds number sufficiently high to insure a fully turbulent wake, but low enough to insure a laminar separation. The apparatus developed for measuring this flow consisted of X-array hot wire probes mounted on the ends of a pair of whirling arms. A computer controlled data acquisition system was slaved to the position of the rotating arm and managed, monitored, edited, and recorded the vast profusion of data which is continuously poured out by the device. Results are presented which show the instantaneous velocity, intermittency, vorticity, and stress fields as a function of phase for the first six diameters of the near wake. The stresses in the near wake emerge as a concatenation of peaks and valleys, some the result of strong induced motions in the outer flow which cause free stream fluid to move rapidly inward toward the center of the wake, others the result of the random motions of the background turbulence.

Three dimensional mean velocity and turbulence characteristics in the annulus wall region of an axial flow compressor rotor passage

NASA Technical Reports Server (NTRS)

Davino, R.; Lakshminarayana, B.

1982-01-01

The experiment was performed using the rotating hot-wire technique within the rotor blade passage and the stationary hot-wire technique for the exitflow of the rotor blade passage. The measurements reveal the effect of rotation and subsequent flow interactions upon the rotor blade flowfield and wake development in the annulus-wall region. The flow near the rotor blade tips is found to be highly complex due to the interaction of the annulus-wall boundary layer, the blade boundary layers, the tip leakage flow, and the secondary flow. Within the blade passage, this interaction results in an appreciable radial inward flow as well as a defect in the mainstream velocity near the mid-passage. Turbulence levels within this region are very high. This indicates a considerable extent of flow mixing due to the viscous flow interactions. The size and strength of this loss core is found to grow with axial distance from the blade trailing edge. The nature of the rotor blade exit-flow was dominated by the wake development.

Respiratory effects of work in retail food stores. III. Pulmonary function findings.

PubMed

Wegman, D H; Eisen, E A; Smith, T J; Greaves, I A; Fine, L J

1987-06-01

Findings are reported from a prospective morbidity study which examined the effects on pulmonary function associated with the particulate and gaseous air contaminants to which retail food store workers are exposed. A total of 685 supermarket employees (including meat wrappers, meat cutters and store clerks) performed standard ventilatory function tests [forced expiratory volume in 1 s (FEV1.0) and forced vital capacity (FVC)] during a base-line survey. Those available four years later (305) were resurveyed in a similar manner. A suggestive chronic effect on pulmonary function was shown in those with high cumulative exposures and allergic history. Among those workers who had continuous exposure to air contaminants in settings with "hot-wire" plastic wrap film cutters the annual rates of change in FEV1.0 and FVC were twice as great as the changes found among comparable workers who were not exposed to fumes from wrapping film. Those who switched from the "hot-wire" to the "cool-rod" cutters during the course of the follow-up had intermediate rates of change in lung function.

Numerical and Experimental Study of Wake Redirection Techniques in a Boundary Layer Wind Tunnel

NASA Astrophysics Data System (ADS)

Wang, J.; Foley, S.; Nanos, E. M.; Yu, T.; Campagnolo, F.; Bottasso, C. L.; Zanotti, A.; Croce, A.

2017-05-01

The aim of the present paper is to validate a wind farm LES framework in the context of two distinct wake redirection techniques: yaw misalignment and individual cyclic pitch control. A test campaign was conducted using scaled wind turbine models in a boundary layer wind tunnel, where both particle image velocimetry and hot-wire thermo anemometers were used to obtain high quality measurements of the downstream flow. A LiDAR system was also employed to determine the non-uniformity of the inflow velocity field. A high-fidelity large-eddy simulation lifting-line model was used to simulate the aerodynamic behavior of the system, including the geometry of the wind turbine nacelle and tower. A tuning-free Lagrangian scale-dependent dynamic approach was adopted to improve the sub-grid scale modeling. Comparisons with experimental measurements are used to systematically validate the simulations. The LES results are in good agreement with the PIV and hot-wire data in terms of time-averaged wake profiles, turbulence intensity and Reynolds shear stresses. Discrepancies are also highlighted, to guide future improvements.

The spectrum of wind speed fluctuations encountered by a rotating blade of a wind energy conversion system

NASA Astrophysics Data System (ADS)

Connell, J. R.

1982-01-01

The results of anemometer, hot-wire anemometer, and laser anemometer array and crosswind sampling of wind speed and turbulence in an area swept by intermediate-to-large wind turbine blades are presented, with comparisons made with a theoretical model for the wind fluctuations. A rotating frame of reference was simulated by timing the anemometric readings at different points of the actuator disk area to coincide with the moment a turbine blade would pass through the point. The hot-wire sensors were mounted on an actual rotating boom, while the laser scanned the wind velocity field in a vertical crosswind circle. The midfrequency region of the turbulence spectrum was found to be depleted, with energy shifted to the high end of the spectrum, with an additional peak at the rotation frequency of the rotor. A model is developed, assuming homogeneous, isotropic turbulence, to reproduce the observed spectra and verify and extend scaling relations using turbine and atmospheric length and time scales. The model is regarded as useful for selecting wind turbine hub heights and rotor rotation rates.

An experimental investigation of turbulent boundary layers along curved surfaces

NASA Technical Reports Server (NTRS)

So, R. M. C.; Mellor, G. L.

1972-01-01

A curved wall tunnel was designed, and an equilibrium turbulent boundary layer was set up on the straight section preceding the curved test section. Turbulent boundary layer flows with uniform and adverse pressure distributions along convex and concave walls were investigated. Hot-wire measurements along the convex surface indicated that turbulent mixing between fluid layers was very much reduced. However, the law of the wall held and the skin friction, thus determined, correlated well with other measurements. Hot-wire measurements along the concave test wall revealed a system of longitudinal vortices inside the boundary layer and confirmed that concave curvature enhances mixing. A self-consistent set of turbulent boundary layer equations for flows along curved surfaces was derived together with a modified eddy viscosity. Solution of these equations together with the modified eddy viscosity gave results that correlated well with the present data on flows along the convex surface with arbitrary pressure distribution. However, it could only be used to predict the mean characteristics of the flow along concave walls because of the existence of the system of longitudinal vortices inside the boundary layer.

Exciton shelves for charge and energy transport in third-generation quantum-dot devices

NASA Astrophysics Data System (ADS)

Goodman, Samuel; Singh, Vivek; Noh, Hyunwoo; Casamada, Josep; Chatterjee, Anushree; Cha, Jennifer; Nagpal, Prashant

2014-03-01

Quantum dots are semiconductor nanocrystallites with size-dependent quantum-confined energy levels. While they have been intensively investigated to utilize hot-carriers for photovoltaic applications, to bridge the mismatch between incident solar photons and finite bandgap of semiconductor photocells, efficient charge or exciton transport in quantum-dot films has proven challenging. Here we show development of new coupled conjugated molecular wires with ``exciton shelves'', or different energy levels, matched with the multiple energy levels of quantum dots. Using single nanoparticle and ensemble device measurements we show successful extraction and transport of both bandedge and high-energy charge carriers, and energy transport of excitons. We demonstrate using measurements of electronic density of states, that careful matching of energy states of quantum-dot with molecular wires is important, and any mismatch can generate midgap states leading to charge recombination and reduced efficiency. Therefore, these exciton-shelves and quantum dots can lead to development of next-generation photovoltaic and photodetection devices using simultaneous transport of bandedge and hot-carriers or energy transport of excitons in these nanostructured solution-processed films.

Target surface area effects on hot electron dynamics from high intensity laser–plasma interactions

DOE PAGES

Zulick, C.; Raymond, A.; McKelvey, A.; ...

2016-06-15

Reduced surface area targets were studied using an ultra-high intensity femtosecond laser in order to determine the effect of electron sheath field confinement on electron dynamics. X-ray emission due to energetic electrons was imaged using a K α imaging crystal. Electrons were observed to travel along the surface of wire targets, and were slowed mainly by the induced fields. Targets with reduced surface areas were correlated with increased hot electron densities and proton energies. Furthermore, Hybrid Vlasov–Fokker–Planck simulations demonstrated increased electric sheath field strength in reduced surface area targets.

Demonstration of Scalable Nernst Voltage in a Coiled Galfenol Wire

NASA Astrophysics Data System (ADS)

Codecido, Emilio; Yang, Zihao; Marquez, Jason; Zheng, Yuanhua; Heremans, Joseph; Myers, Roberto

Transverse thermopower by the Nernst effect is usually considered far too weak an effect for waste heat recovery and power generation. We propose that magnetostriction provides a pathway to enhance the Nernst effect because it increases phonon and magnon coupling. Here, we measure the Nernst coefficient in the magnetostrictive alloy, Galfenol (Fe0.85Ga0.15) and observe an extraordinarily large Nernst coefficient at room temperature of 4 μV/KT. Next we demonstrate a new geometry for efficient and low cost power generation by wrapping Galfenol wire around a hot cylinder. This coil geometry results in a radial temperature gradient direction. With a magnetic field applied in the axial direction, a uniform Nernst electric field is produced along the azimuthal direction at every point along the coil. As a result of this geometry, the Nernst voltage is shown to increase linearly with wire length, proving the concept of scalable Nernst thermal power generation.

Gas-Phase Synthesis of Gold- and Silica-Coated Nanoparticles

NASA Astrophysics Data System (ADS)

Boies, Adam Meyer

2011-12-01

Composite nanoparticles consisting of separate core-shell materials are of interest for a variety of biomedical and industrial applications. By combining different materials at the nanoscale, particles can exhibit enhanced or multi-functional behavior such as plasmon resonance combined with superparamagnetism. Gas-phase nanoparticle synthesis processes are promising because they can continuously produce particles with high mass-yield rates. In this dissertation, new methods are investigated for producing gas-phase coatings of nanoparticles in an "assembly-line" fashion. Separate processes are developed to create coatings from silica and gold that can be used with a variety of core-particle chemistries. A photoinduced chemical vapor deposition (photo-CVD) method is used to produce silica coatings from tetraethyl orthosilicate (TEOS) on the surface of nanoparticles (diameter ˜5--70 nm). Tandem differential mobility analysis (TDMA) of the process demonstrates that particle coatings can be produced with controllable thicknesses (˜1--10 nm) by varying system parameters such as precursor flow rate. Electron microscopy and infrared spectroscopy confirm that the photo-CVD films uniformly coat the particles and that the coatings are silica. In order to describe the coating process a chemical mechanism is proposed that includes gas-phase, surface and photochemical reactions. A chemical kinetics model of the mechanism indicates that photo-CVD coating proceeds primarily through the photodecomposition of TEOS which removes ethyl groups, thus creating activated TEOS species. The activated TEOS then adsorbs onto the surface of the particle where a series of subsequent reactions remove the remaining ethyl groups to produce a silica film with an open site for further attachment. The model results show good agreement with the experimentally measured coating trends, where increased TEOS flow increases coating thickness and increased nitrogen flow decreases coating thickness. Gold decoration of nanoparticles is accomplished by evaporation of solid gold in the presence of an aerosol flow. A hot-wire generation method is developed where gold particles are produced from a composite gold-platinum wire. Investigations of the hot-wire generator show that it can produce particles with a range of sizes and that more uniform, non-agglomerated particles are produced when using smaller diameter tubes where gas velocities across the wire are higher and recirculation zones are diminished. When gold is evaporated in the presence of silica nanoparticles, the silica aerosol is decorated by gold through either homogeneous gold nucleation and subsequent scavenging by the silica nanoparticles, or by heterogeneous nucleation on the silica surface in which the gold "balls up" due to the high surface tension of gold on silica. In both cases the resulting particles exhibit a plasmon absorbance resonance typical of gold nanoparticles (lambda˜550 nm). Finally, the silica coating and gold decoration processes are combined with a thermal plasma technique for synthesizing iron-oxide to produce tri-layer nanoparticles.

System and method for evaluating a wire conductor

DOEpatents

Panozzo, Edward; Parish, Harold

2013-10-22

A method of evaluating an electrically conductive wire segment having an insulated intermediate portion and non-insulated ends includes passing the insulated portion of the wire segment through an electrically conductive brush. According to the method, an electrical potential is established on the brush by a power source. The method also includes determining a value of electrical current that is conducted through the wire segment by the brush when the potential is established on the brush. The method additionally includes comparing the value of electrical current conducted through the wire segment with a predetermined current value to thereby evaluate the wire segment. A system for evaluating an electrically conductive wire segment is also disclosed.

Thermal-hydraulic behaviors of vapor-liquid interface due to arrival of a pressure wave

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inoue, Akira; Fujii, Yoshifumi; Matsuzaki, Mitsuo

In the vapor explosion, a pressure wave (shock wave) plays a fundamental role for triggering, propagation and enhancement of the explosion. Energy of the explosion is related to the magnitude of heat transfer rate from hot liquid to cold volatile one. This is related to an increasing rate of interface area and to an amount of transient heat flux between the liquids. In this study, the characteristics of transient heat transfer and behaviors of vapor film both on the platinum tube and on the hot melt tin drop, under same boundary conditions have been investigated. It is considered that theremore » exists a fundamental mechanism of the explosion in the initial expansion process of the hot liquid drop immediately after arrival of pressure wave. The growth rate of the vapor film is much faster on the hot liquid than that on the solid surface. Two kinds of roughness were observed, one due to the Taylor instability, by rapid growth of the explosion bubble, and another, nucleation sites were observed at the vapor-liquid interface. Based on detailed observation of early stage interface behaviors after arrival of a pressure wave, the thermal fragmentation mechanism is proposed.« less

Sliding bubbles on a hot horizontal wire in a subcooled bath

NASA Astrophysics Data System (ADS)

Duchesne, Alexis; Dubois, Charles; Caps, Hervé

2015-11-01

When a wire is heated up to the boiling point in a liquid bath some bubbles will nucleate on the wire surface. Traditional nucleate boiling theory predicts that bubbles generate from active nucleate site, grow up and depart from the heating surface due to buoyancy and inertia. However, an alternative scenario is presented in the literature for a subcooled bath: bubbles slide along the horizontal wire before departing. New experiments were performed by using a constantan wire and different liquids, varying the injected power. Silicone oil, water and even liquid nitrogen were tested in order to vary wetting conditions, liquid viscosities and surface tensions. We explored the influence of the wire diameter and of the subcooled bath temperature. We observed, of course, sliding motion, but also a wide range of behaviors from bubbles clustering to film boiling. We noticed that bubbles could change moving sense, especially when encountering with another bubble. The bubble speed is carefully measured and can reach more than 100 mm/s for a millimetric bubble. We investigated the dependence of the speed on the different parameters and found that this speed is, for a given configuration, quite independent of the injected power. We understand these phenomena in terms of Marangoni effects. This project has been financially supported by ARC SuperCool contract of the University of Liège.

Analysis of hybrid electric/thermofluidic inputs for wet shape memory alloy actuators

NASA Astrophysics Data System (ADS)

Flemming, Leslie; Mascaro, Stephen

2013-01-01

A wet shape memory alloy (SMA) actuator is characterized by an SMA wire embedded within a compliant fluid-filled tube. Heating and cooling of the SMA wire produces a linear contraction and extension of the wire. Thermal energy can be transferred to and from the wire using combinations of resistive heating and free/forced convection. This paper analyzes the speed and efficiency of a simulated wet SMA actuator using a variety of control strategies involving different combinations of electrical and thermofluidic inputs. A computational fluid dynamics (CFD) model is used in conjunction with a temperature-strain model of the SMA wire to simulate the thermal response of the wire and compute strains, contraction/extension times and efficiency. The simulations produce cycle rates of up to 5 Hz for electrical heating and fluidic cooling, and up to 2 Hz for fluidic heating and cooling. The simulated results demonstrate efficiencies up to 0.5% for electric heating and up to 0.2% for fluidic heating. Using both electric and fluidic inputs concurrently improves the speed and efficiency of the actuator and allows for the actuator to remain contracted without continually delivering energy to the actuator, because of the thermal capacitance of the hot fluid. The characterized speeds and efficiencies are key requirements for implementing broader research efforts involving the intelligent control of electric and thermofluidic networks to optimize the speed and efficiency of wet actuator arrays.

Femtosecond tracking of carrier relaxation in germanium with extreme ultraviolet transient reflectivity

NASA Astrophysics Data System (ADS)

Kaplan, Christopher J.; Kraus, Peter M.; Ross, Andrew D.; Zürch, Michael; Cushing, Scott K.; Jager, Marieke F.; Chang, Hung-Tzu; Gullikson, Eric M.; Neumark, Daniel M.; Leone, Stephen R.

2018-05-01

Extreme ultraviolet (XUV) transient reflectivity around the germanium M4 ,5 edge (3 d core-level to valence transition) at 30 eV is advanced to obtain the transient dielectric function of crystalline germanium [100] on femtosecond to picosecond time scales following photoexcitation by broadband visible-to-infrared (VIS/NIR) pulses. By fitting the transient dielectric function, carrier-phonon induced relaxations are extracted for the excited carrier distribution. The measurements reveal a hot electron relaxation rate of 3.2 ±0.2 ps attributed to the X -L intervalley scattering and a hot hole relaxation rate of 600 ±300 fs ascribed to intravalley scattering within the heavy hole (HH) band, both in good agreement with previous work. An overall energy shift of the XUV dielectric function is assigned to a thermally induced band gap shrinkage by formation of acoustic phonons, which is observed to be on a timescale of 4-5 ps, in agreement with previously measured optical phonon lifetimes. The results reveal that the transient reflectivity signal at an angle of 66∘ with respect to the surface normal is dominated by changes to the real part of the dielectric function, due to the near critical angle of incidence of the experiment (66∘-70∘) for the range of XUV energies used. This work provides a methodology for interpreting XUV transient reflectivity near core-level transitions, and it demonstrates the power of the XUV spectral region for measuring ultrafast excitation dynamics in solids.

Flight experience with a fail-operational digital fly-by-wire control system

NASA Technical Reports Server (NTRS)

Brown, S. R.; Szalai, K. J.

1977-01-01

The NASA Dryden Flight Research Center is flight testing a triply redundant digital fly-by-wire (DFBW) control system installed in an F-8 aircraft. The full-time, full-authority system performs three-axis flight control computations, including stability and command augmentation, autopilot functions, failure detection and isolation, and self-test functions. Advanced control law experiments include an active flap mode for ride smoothing and maneuver drag reduction. This paper discusses research being conducted on computer synchronization, fault detection, fault isolation, and recovery from transient faults. The F-8 DFBW system has demonstrated immunity from nuisance fault declarations while quickly identifying truly faulty components.

The Relation between Hot Flashes and Ambulatory Blood Pressure: The Hilo Women’s Health Study

PubMed Central

Brown, Daniel E.; Sievert, Lynnette L.; Morrison, Lynn A.; Rahberg, Nichole; Reza, Angela

2011-01-01

Objectives Hot flashes (HFs) have been associated with elevated blood pressure, but studies have not examined the relationship between objectively measured HFs and blood pressure during normal daily activities. The objectives of this study are to examine ambulatory blood pressure (BP) differences between women who report HFs and those who do not, and to observe whether an objectively measured HF is associated with transient changes in BP. Methods A sample of 202 women in Hilo, Hawaii aged 45–55 years were asked to fill out a questionnaire that included demographic information and an inventory of symptoms. The women underwent simultaneous 24-hour monitoring of ambulatory BP and HFs, while keeping a diary that included mood and HF reports. Results No significant difference was present in mean BP between women who reported having a HF during the past 2 weeks and those who did not. When measurements controlled for negative mood reports and posture, there was a highly significant elevation in Z scores of systolic BP when a measured, objective HF occurred within 10 minutes preceding a BP reading, and a significant elevation of Z scores of diastolic BP when a subjectively reported HF occurred within 10 minutes after a BP reading. Conclusions These results suggest that objectively measured HFs precede transient elevations of systolic BP, but it is unclear if there is a causal relationship. These results also suggest that women experience subjective HFs within 10 minutes after a transient increase in diastolic BP. Again, the causal relationship is not understood. PMID:21183716

Preliminary report on the CTS transient event counter performance through the 1976 spring eclipse season

NASA Technical Reports Server (NTRS)

Stevens, N. J.; Levell, R. R.; Klinect, V. W.

1976-01-01

The transient event counter (TEC), senses and counts transients having a voltage rise of greater than five volts in three separate wire harnesses: the attitude control harness, the solar array instrumentation harness and the solar array power harness. The operational characteristics of TEC are defined and the preliminary results obtained through the first 90 days of operation including the spring 1976 eclipse season are presented. The results show that the Communications Technology Satellite was charged to the point where discharges occurred. The discharge induced transients did not cause any anomalous events in spacecraft operation. The data indicate that discharges can occur at any time during the day without preference to any local time quadrant. The number of discharges occurring in the one second sample interval are greater than anticipated. The compilation and review of the data is continuing.

Chemical fabrication of heterometallic nanogaps for molecular transport junctions.

PubMed

Chen, Xiaodong; Yeganeh, Sina; Qin, Lidong; Li, Shuzhou; Xue, Can; Braunschweig, Adam B; Schatz, George C; Ratner, Mark A; Mirkin, Chad A

2009-12-01

We report a simple and reproducible method for fabricating heterometallic nanogaps, which are made of two different metal nanorods separated by a nanometer-sized gap. The method is based upon on-wire lithography, which is a chemically enabled technique used to synthesize a wide variety of nanowire-based structures (e.g., nanogaps and disk arrays). This method can be used to fabricate pairs of metallic electrodes, which exhibit distinct work functions and are separated by gaps as small as 2 nm. Furthermore, we demonstrate that a symmetric thiol-terminated molecule can be assembled into such heterometallic nanogaps to form molecular transport junctions (MTJs) that exhibit molecular diode behavior. Theoretical calculations demonstrate that the coupling strength between gold and sulfur (Au-S) is 2.5 times stronger than that of Pt-S. In addition, the structures form Raman hot spots in the gap, allowing the spectroscopic characterization of the molecules that make up the MTJs.

Characterization of a Laser-Generated Perturbation in High-Speed Flow for Receptivity Studies

NASA Technical Reports Server (NTRS)

Chou, Amanda; Schneider, Steven P.; Kegerise, Michael A.

2014-01-01

A better understanding of receptivity can contribute to the development of an amplitude-based method of transition prediction. This type of prediction model would incorporate more physics than the semi-empirical methods, which are widely used. The experimental study of receptivity requires a characterization of the external disturbances and a study of their effect on the boundary layer instabilities. Characterization measurements for a laser-generated perturbation were made in two different wind tunnels. These measurements were made with hot-wire probes, optical techniques, and pressure transducer probes. Existing methods all have their limitations, so better measurements will require the development of new instrumentation. Nevertheless, the freestream laser-generated perturbation has been shown to be about 6 mm in diameter at a static density of about 0.045 kg/cubic m. The amplitude of the perturbation is large, which may be unsuitable for the study of linear growth.

Pressure Flammability Thresholds in Oxygen of Selected Aerospace Materials

NASA Technical Reports Server (NTRS)

Hirsch, David; Williams, Jim; Harper, Susana; Beeson, Harold; Ruff, Gary; Pedley, Mike

2010-01-01

The experimental approach consisted of concentrating the testing in the flammability transition zone following the Bruceton Up-and-Down Method. For attribute data, the method has been shown to be very repeatable and most efficient. Other methods for characterization of critical levels (Karberand Probit) were also considered. The data yielded the upward limiting pressure index (ULPI), the pressure level where approx.50% of materials self-extinguish in a given environment.Parametric flammability thresholds other than oxygen concentration can be determined with the methodology proposed for evaluating the MOC when extinguishment occurs. In this case, a pressure threshold in 99.8% oxygen was determined with the methodology and found to be 0.4 to 0.9 psia for typical spacecraft materials. Correlation of flammability thresholds obtained with chemical, hot wire, and other ignition sources will be conducted to provide recommendations for using alternate ignition sources to evaluate flammability of aerospace materials.

Dual wire welding torch and method

DOEpatents

Diez, Fernando Martinez; Stump, Kevin S.; Ludewig, Howard W.; Kilty, Alan L.; Robinson, Matthew M.; Egland, Keith M.

2009-04-28

A welding torch includes a nozzle with a first welding wire guide configured to orient a first welding wire in a first welding wire orientation, and a second welding wire guide configured to orient a second welding wire in a second welding wire orientation that is non-coplanar and divergent with respect to the first welding wire orientation. A method of welding includes moving a welding torch with respect to a workpiece joint to be welded. During moving the welding torch, a first welding wire is fed through a first welding wire guide defining a first welding wire orientation and a second welding wire is fed through a second welding wire guide defining a second welding wire orientation that is divergent and non-coplanar with respect to the first welding wire orientation.

Specification and testing for power by wire aircraft

NASA Technical Reports Server (NTRS)

Hansen, Irving G.; Kenney, Barbara H.

1993-01-01

A power by wire aircraft is one in which all active functions other than propulsion are implemented electrically. Other nomenclature are 'all electric airplane,' or 'more electric airplane.' What is involved is the task of developing and certifying electrical equipment to replace existing hydraulics and pneumatics. When such functions, however, are primary flight controls which are implemented electrically, new requirements are imposed that were not anticipated by existing power system designs. Standards of particular impact are the requirements of ultra-high reliability, high peak transient bi-directional power flow, and immunity to electromagnetic interference and lightning. Not only must the electromagnetic immunity of the total system be verifiable, but box level tests and meaningful system models must be established to allow system evaluation. This paper discusses some of the problems, the system modifications involved, and early results in establishing wiring harness and interface susceptibility requirements.

Ultrafast Surface-Enhanced Raman Probing of the Role of Hot Electrons in Plasmon-Driven Chemistry.

PubMed

Brandt, Nathaniel C; Keller, Emily L; Frontiera, Renee R

2016-08-18

Hot electrons generated through plasmonic excitations in metal nanostructures show great promise for efficiently driving chemical reactions with light. However, the lifetime, yield, and mechanism of action of plasmon-generated hot electrons involved in a given photocatalytic process are not well understood. Here, we develop ultrafast surface-enhanced Raman scattering (SERS) as a direct probe of plasmon-molecule interactions in the plasmon-catalyzed dimerization of 4-nitrobenzenethiol to p,p'-dimercaptoazobenzene. Ultrafast SERS probing of these molecular reporters in plasmonic hot spots reveals transient Fano resonances, which we attribute to near-field coupling of Stokes-shifted photons to hot electron-driven metal photoluminescence. Surprisingly, we find that hot spots that yield more photoluminescence are much more likely to drive the reaction, which indirectly proves that plasmon-generated hot electrons induce the photochemistry. These ultrafast SERS results provide insight into the relative reactivity of different plasmonic hot spot environments and quantify the ultrafast lifetime of hot electrons involved in plasmon-driven chemistry.

Methods for describing the electromagnetic properties of silver and gold nanoparticles.

PubMed

Zhao, Jing; Pinchuk, Anatoliy O; McMahon, Jeffrey M; Li, Shuzhou; Ausman, Logan K; Atkinson, Ariel L; Schatz, George C

2008-12-01

This Account provides an overview of the methods that are currently being used to study the electromagnetics of silver and gold nanoparticles, with an emphasis on the determination of extinction and surface-enhanced Raman scattering (SERS) spectra. These methods have proven to be immensely useful in recent years for interpreting a wide range of nanoscience experiments and providing the capability to describe optical properties of particles up to several hundred nanometers in dimension, including arbitrary particle structures and complex dielectric environments (adsorbed layers of molecules, nearby metal films, and other particles). While some of the methods date back to Mie's celebrated work a century ago, others are still at the forefront of algorithm development in computational electromagnetics. This Account gives a qualitative description of the physical and mathematical basis behind the most commonly used methods, including both analytical and numerical methods, as well as representative results of applications that are relevant to current experiments. The analytical methods that we discuss are either derived from Mie theory for spheres or from the quasistatic (Gans) model as applied to spheres and spheroids. In this discussion, we describe the use of Mie theory to determine electromagnetic contributions to SERS enhancements that include for retarded dipole emission effects, and the use of the quasistatic approximation for spheroidal particles interacting with dye adsorbate layers. The numerical methods include the discrete dipole approximation (DDA), the finite difference time domain (FDTD) method, and the finite element method (FEM) based on Whitney forms. We discuss applications such as using DDA to describe the interaction of two gold disks to define electromagnetic hot spots, FDTD for light interacting with metal wires that go from particle-like plasmonic response to the film-like transmission as wire dimension is varied, and FEM studies of electromagnetic fields near cubic particles.

Numerical analysis on temperature field in single-wire flux-aided backing-submerged arc welding

NASA Astrophysics Data System (ADS)

Pu, Juan; Wu, Ming Fang; Pan, Haichao

2017-07-01

Single-wire flux-aided backing-submerged arc welding (FAB-SAW) technology has been widely used to weld thick steel plate due to its easy assembly and high heat input. The microstructure and property of welded joint are closely related to the thermal field of FAB-SAW process. In this research, the feature of thermal field for single-wire FAB-SAW was investigated. Based on the heat transfer mechanism, a three-dimensional transient model for thermal field was developed based on the influence of steel thickness, groove angle and ceramic backing. The temperature profile in single-wire FAB-SAW of D36 steel under different welding conditions was simulated by ANSYS. The characteristic of thermal field was analyzed and the influences of groove angle on temperature field for different plate thicknesses were discussed. The calculated geometries and dimensions of weld cross-section under different conditions show a good agreement with the experimental results. This newly built model can describe the thermal field accurately, which would be helpful to understanding the thermophysical mechanism of FAB-SAW and optimizing the welding process.

On the Analysis Methods for the Time Domain and Frequency Domain Response of a Buried Objects*

NASA Astrophysics Data System (ADS)

Poljak, Dragan; Šesnić, Silvestar; Cvetković, Mario

2014-05-01

There has been a continuous interest in the analysis of ground-penetrating radar systems and related applications in civil engineering [1]. Consequently, a deeper insight of scattering phenomena occurring in a lossy half-space, as well as the development of sophisticated numerical methods based on Finite Difference Time Domain (FDTD) method, Finite Element Method (FEM), Boundary Element Method (BEM), Method of Moments (MoM) and various hybrid methods, is required, e.g. [2], [3]. The present paper deals with certain techniques for time and frequency domain analysis, respectively, of buried conducting and dielectric objects. Time domain analysis is related to the assessment of a transient response of a horizontal straight thin wire buried in a lossy half-space using a rigorous antenna theory (AT) approach. The AT approach is based on the space-time integral equation of the Pocklington type (time domain electric field integral equation for thin wires). The influence of the earth-air interface is taken into account via the simplified reflection coefficient arising from the Modified Image Theory (MIT). The obtained results for the transient current induced along the electrode due to the transmitted plane wave excitation are compared to the numerical results calculated via an approximate transmission line (TL) approach and the AT approach based on the space-frequency variant of the Pocklington integro-differential approach, respectively. It is worth noting that the space-frequency Pocklington equation is numerically solved via the Galerkin-Bubnov variant of the Indirect Boundary Element Method (GB-IBEM) and the corresponding transient response is obtained by the aid of inverse fast Fourier transform (IFFT). The results calculated by means of different approaches agree satisfactorily. Frequency domain analysis is related to the assessment of frequency domain response of dielectric sphere using the full wave model based on the set of coupled electric field integral equations for surfaces. The numerical solution is carried out by means of the improved variant of the Method of Moments (MoM) providing numerically stable and an efficient procedure for the extraction of singularities arising in integral expressions. The proposed analysis method is compared to the results obtained by using some commercial software packages. A satisfactory agreement has been achieved. Both approaches discussed throughout this work and demonstrated on canonical geometries could be also useful for benchmark purpose. References [1] L. Pajewski et al., Applications of Ground Penetrating Radar in Civil Engineering - COST Action TU1208, 2013. [2] U. Oguz, L. Gurel, Frequency Responses of Ground-Penetrating Radars Operating Over Highly Lossy Grounds, IEEE Trans. Geosci. and Remote sensing, Vol. 40, No 6, 2002. [3] D.Poljak, Advanced Modeling in Computational electromagnetic Compatibility, John Wiley and Sons, New York 2007. *This work benefited from networking activities carried out within the EU funded COST Action TU1208 "Civil Engineering Applications of Ground Penetrating Radar."

24 CFR 3280.808 - Wiring methods and materials.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 24 Housing and Urban Development 5 2011-04-01 2011-04-01 false Wiring methods and materials. 3280... § 3280.808 Wiring methods and materials. (a) Except as specifically permitted by this part, the wiring methods and materials specified in the National Electrical Code, NFPA No. 70-2005, must be used in...

Alternatives Analysis for the Resumption of Transient Testing Program

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee Nelson

2013-11-01

An alternatives analysis was performed for resumption of transient testing. The analysis considered eleven alternatives – including both US international facilities. A screening process was used to identify two viable alternatives from the original eleven. In addition, the alternatives analysis includes a no action alternative as required by the National Environmental Policy Act (NEPA). The alternatives considered in this analysis included: 1. Restart the Transient Reactor Test Facility (TREAT) 2. Modify the Annular Core Research Reactor (ACRR) which includes construction of a new hot cell and installation of a new hodoscope. 3. No Action

Numerical calculation of primary slot leakage inductance of a Single-sided HTS linear induction motor used for linear metro

NASA Astrophysics Data System (ADS)

Li, Dong; Wen, Yinghong; Li, Weili; Fang, Jin; Cao, Junci; Zhang, Xiaochen; Lv, Gang

2017-03-01

In the paper, the numerical method calculating asymmetric primary slot leakage inductances of Single-sided High-Temperature Superconducting (HTS) Linear Induction Motor (HTS LIM) is presented. The mathematical and geometric models of three-dimensional nonlinear transient electromagnetic field are established and the boundary conditions are also given. The established model is solved by time-stepping Finite Element Method (FEM). Then, the three-phase asymmetric primary slot leakage inductances under different operation conditions are calculated by using the obtained electromagnetic field distribution. The influences of the special effects such as longitudinal end effects, transversal edge effects, etc. on the primary slot leakage inductance are investigated. The presented numerical method is validated by experiments carried out on a 3.5 kW prototype with copper wires which has the same structures with the HTS LIM.

Method and apparatus for monitoring two-phase flow. [PWR

DOEpatents

Sheppard, J.D.; Tong, L.S.

1975-12-19

A method and apparatus for monitoring two-phase flow is provided that is particularly related to the monitoring of transient two-phase (liquid-vapor) flow rates such as may occur during a pressurized water reactor core blow-down. The present invention essentially comprises the use of flanged wire screens or similar devices, such as perforated plates, to produce certain desirable effects in the flow regime for monitoring purposes. One desirable effect is a measurable and reproducible pressure drop across the screen. The pressure drop can be characterized for various known flow rates and then used to monitor nonhomogeneous flow regimes. Another useful effect of the use of screens or plates in nonhomogeneous flow is that such apparatus tends to create a uniformly dispersed flow regime in the immediate downstream vicinity. This is a desirable effect because it usually increases the accuracy of flow rate measurements determined by conventional methods.

Two-phase flow pattern measurements with a wire mesh sensor in a direct steam generating solar thermal collector

NASA Astrophysics Data System (ADS)

Berger, Michael; Mokhtar, Marwan; Zahler, Christian; Willert, Daniel; Neuhäuser, Anton; Schleicher, Eckhard

2017-06-01

At Industrial Solar's test facility in Freiburg (Germany), two phase flow patterns have been measured by using a wire mesh sensor from Helmholtz Zentrum Dresden-Rossendorf (HZDR). Main purpose of the measurements was to compare observed two-phase flow patterns with expected flow patterns from models. The two-phase flow pattern is important for the design of direct steam generating solar collectors. Vibrations should be avoided in the peripheral piping, and local dry-outs or large circumferential temperature gradients should be prevented in the absorber tubes. Therefore, the choice of design for operation conditions like mass flow and steam quality are an important step in the engineering process of such a project. Results of a measurement with the wire mesh sensor are the flow pattern and the plug or slug frequency at the given operating conditions. Under the assumption of the collector power, which can be assumed from previous measurements at the same collector and adaption with sun position and incidence angle modifier, also the slip can be evaluated for a wire mesh sensor measurement. Measurements have been performed at different mass flows and pressure levels. Transient behavior has been tested for flashing, change of mass flow, and sudden changes of irradiation (cloud simulation). This paper describes the measurements and the method of evaluation. Results are shown as extruded profiles in top view and in side view. Measurement and model are compared. The tests have been performed at low steam quality, because of the limits of the test facility. Conclusions and implications for possible future measurements at larger collectors are also presented in this paper.

Anisotropic electrical conduction and reduction in dangling-bond density for polycrystalline Si films prepared by catalytic chemical vapor deposition

NASA Astrophysics Data System (ADS)

Niikura, Chisato; Masuda, Atsushi; Matsumura, Hideki

1999-07-01

Polycrystalline Si (poly-Si) films with high crystalline fraction and low dangling-bond density were prepared by catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD. Directional anisotropy in electrical conduction, probably due to structural anisotropy, was observed for Cat-CVD poly-Si films. A novel method to separately characterize both crystalline and amorphous phases in poly-Si films using anisotropic electrical conduction was proposed. On the basis of results obtained by the proposed method and electron spin resonance measurements, reduction in dangling-bond density for Cat-CVD poly-Si films was achieved using the condition to make the quality of the included amorphous phase high. The properties of Cat-CVD poly-Si films are found to be promising in solar-cell applications.

Formation of Bi2Sr2CaCu2O x /Ag multifilamentary metallic precursor powder-in-tube wires

NASA Astrophysics Data System (ADS)

Zhang, Yun; Koch, Carl C.; Schwartz, Justin

2016-12-01

Previously, a metallic precursor (MP) approach to synthesizing Bi2Sr2CaCu2O x (Bi2212), with a homogeneous mixture of Bi, Sr, Ca, Cu and Ag was produced by mechanical alloying. Here, Bi2212/Ag round multifilamentary wire is manufactured using a metallic precursor powder-in-tube (MPIT) process. The MP powders were packed into a pure Ag tube in an Ar atmosphere and then sealed. After deformation, multifilamentary round wires and rolled tapes were heat treated in flowing oxygen through three stages: oxidation, conversion and partial-melt processing (PMP). Processing-microstructure-property relationships on 20-50 mm long multifilamentary round wires and rolled tapes were studied extensively. It is shown that conventional wire deformation processes, optimized for oxide-powder-in-tube wires, are not effective for deforming MPIT wires, and that as with prior studies of MPIT Bi2Sr2Ca2Cu3O y conductors, hot extrusion is required for obtaining a multifilamentary structure with fine filaments. As a result, the Bi2212 MPIT wires reported here have low engineering critical current density. Nonetheless, by focusing on sections of wires that remain intact after deformation, it is also shown that the first heat treatment stage, the oxidation stage, plays a crucial role in chemical homogeneity, phase transformation, and microstructural evolution and three reaction pathways for MP oxidation are presented. Furthermore, it is found the Bi2212 grain alignment within an MPIT filament is significantly different from that found in OPIT filaments after PMP, indicating the formation of highly dense filaments containing Bi2212 fine grains and Ag particles before PMP aids the formation of large, c-axis textured Bi2212 filaments during PMP. These results show that, with improved wire deformation, high critical current density may be obtained via a MPIT process.

Quench degradation limit of multifilamentary AgBi 2Sr 2CaCu 2O x round wires

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Liyang; Li, Pei; Shen, Tengming

Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi 2Sr 2CaCu 2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index ofmore » the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A/mm 2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less

Quench degradation limit of multifilamentary AgBi 2Sr 2CaCu 2O x round wires

DOE PAGES

Ye, Liyang; Li, Pei; Shen, Tengming; ...

2016-02-02

Understanding safe operating limits of composite superconducting wires is important for the design of superconducting magnets. Here we report measurements of quench-induced critical current density Jc degradation in commercial Ag/Bi 2Sr 2CaCu 2O x (Bi-2212) round wires using heater-induced quenches at 4.2 K in self magnetic field that reveal a general degradation behavior. J c degradation strongly depends on the local hot spot temperature T max, and is nearly independent of operating current, the temperature gradient along the conductor dT max/dx, and the temperature rising rate dT max/dt. Both J c and n value (where n is an index ofmore » the sharpness of the superconductor-to-normal transition) exhibit small but irreversible degradation when T max exceeds 400-450 K, and large degradation occurs when Tmax exceeds 550 K. This behavior was consistently found for a series of Bi-2212 wires with widely variable wire architectures and porosity levels in the Bi-2212 filaments, including a wire processed using a standard partial melt processing and in which Bi-2212 filaments are porous, an overpressure processed wire in which Bi-2212 filaments are nearly porosity-free and that has a J c(4.2 K, self field) exceeding 8000 A/mm 2, and a wire that has nearly no filament to filament bridges after reaction. Microstructural observations of degraded wires reveal cracks in the Bi-2212 filaments perpendicular to the wire axis, indicating that the quench-induced I c degradation is primarily driven by strain. These results further suggest that the quench degradation temperature limit depends on the strain state of Bi-2212 filaments and this dependence shall be carefully considered when engineering a high-field Bi-2212 magnet.« less

Preliminary Results from an Integrated Airborne EM and Aeromagnetic Survey in Yellowstone National Park

NASA Astrophysics Data System (ADS)

Dickey, K.; Holbrook, W. S.; Finn, C.; Auken, E.; Carr, B.; Sims, K. W. W.; Bedrosian, P.; Lowenstern, J. B.; Hurwitz, S.; Pedersen, J. B. B.

2017-12-01

Yellowstone National Park hosts over 10,000 thermal features (e.g. geysers, fumaroles, mud pots, and hot springs), yet little is known about the circulation depth of meteoric water feeding these features, nor the lithological and structural bounds on the pathways that guide deep, hot fluids to the surface. Previous near-surface geophysical studies have been effective in imaging shallow hydrothermal pathways in some areas of the park, but these methods are difficult to conduct over the large areas needed to characterize entire hydrothermal systems. Transient electromagnetic (TEM) soundings and 2D direct current (DC) resistivity profiles show that hydrothermal fluids at active sites have a higher electrical conductivity than the surrounding hydrothermally inactive areas. For that reason, airborne TEM is an effective method to characterize large areas and identify hydrothermally active and inactive zones using electrical conductivity. Aeromagnetic data have been useful in mapping faults that localize hot springs, making the integration of aeromagnetic and EM data effective for structurally characterizing fluid pathways. Here we present the preliminary results from an airborne transient electromagnetic (TEM) and magnetic survey acquired jointly by the U.S. Geological Survey (USGS) and the University of Wyoming (UW) in November 2016. We integrate the EM and magnetic data for the purpose of edge detection of rhyolite flow boundaries as well as source depth of hydrothermal features. The maximum horizontal gradient technique applied on magnetic data is a useful tool that used to estimate source depth as well as indicate faults and fractures. The integration of EM with magnetics allows us to distinguish hydrothermally altered fault systems that guide fluids in the subsurface. We have used preliminary 2D inversions of EM from Aarhus Workbench to delineate rhyolite flow edges in the upper 300-600 meters and cross-checked those boundaries with the aeromagnetic map.

In-Flight Validation of a Pilot Rating Scale for Evaluating Failure Transients in Electronic Flight Control Systems

NASA Technical Reports Server (NTRS)

Kalinowski, Kevin F.; Tucker, George E.; Moralez, Ernesto, III

2006-01-01

Engineering development and qualification of a Research Flight Control System (RFCS) for the Rotorcraft Aircrew Systems Concepts Airborne Laboratory (RASCAL) JUH-60A has motivated the development of a pilot rating scale for evaluating failure transients in fly-by-wire flight control systems. The RASCAL RFCS includes a highly-reliable, dual-channel Servo Control Unit (SCU) to command and monitor the performance of the fly-by-wire actuators and protect against the effects of erroneous commands from the flexible, but single-thread Flight Control Computer. During the design phase of the RFCS, two piloted simulations were conducted on the Ames Research Center Vertical Motion Simulator (VMS) to help define the required performance characteristics of the safety monitoring algorithms in the SCU. Simulated failures, including hard-over and slow-over commands, were injected into the command path, and the aircraft response and safety monitor performance were evaluated. A subjective Failure/Recovery Rating (F/RR) scale was developed as a means of quantifying the effects of the injected failures on the aircraft state and the degree of pilot effort required to safely recover the aircraft. A brief evaluation of the rating scale was also conducted on the Army/NASA CH-47B variable stability helicopter to confirm that the rating scale was likely to be equally applicable to in-flight evaluations. Following the initial research flight qualification of the RFCS in 2002, a flight test effort was begun to validate the performance of the safety monitors and to validate their design for the safe conduct of research flight testing. Simulated failures were injected into the SCU, and the F/RR scale was applied to assess the results. The results validate the performance of the monitors, and indicate that the Failure/Recovery Rating scale is a very useful tool for evaluating failure transients in fly-by-wire flight control systems.

Local isotropy and refractive index fluctuations in the surface layer of the atmosphere

NASA Technical Reports Server (NTRS)

Portman, D. J.

1969-01-01

Theoretical and experimental evidence for the existence of local isotropy is briefly examined and conflicting results are found. Recent measurements of temperature spectra support earlier hot wire anemometer and optical scintillation measurements that show little evidence of local isotropy at 1 to 1.5 meters over an extensive uniform and level grass covered field.

Intensity, Scale, and Spectra of Turbulence in Mixing Region of Free Subsonic Jet

NASA Technical Reports Server (NTRS)

Laurence, James C

1956-01-01

Report presents the results of the measurements of intensity of turbulence, the longitudinal and lateral correlation coefficients, and the spectra of turbulence in a 3.5-inch-diameter free jet measured with hot-wire anemometers at exit Mach numbers from 0.2 to 0.7 and Reynolds numbers from 192,000 to 725,000.

Study of Airflow Out of the Mouth During Speech.

ERIC Educational Resources Information Center

Catford, J.C.; And Others

Airflow outside the mouth is diagnostic of articulatory activities in the vocal tract, both total volume-velocity and the distribution of particle velocities over the flow-front being useful for this purpose. A system for recording and displaying both these types of information is described. This consists of a matrix of l6 hot-wire anemometer flow…

Insensitivity of single particle time domain measurements to laser velocimeter 'Doppler ambiguity.'

NASA Technical Reports Server (NTRS)

Johnson, D. A.

1973-01-01

It is shown that single particle time domain measurements in high speed gas flows obtained by a laser velocimeter technique developed for use in wind tunnels are not affected by the so-called 'Doppler ambiguity.' A comparison of hot-wire anemometer and laser velocimeter measurements taken under similar flow conditions is used for the demonstration.

Solar Water Heater Installation Package

NASA Technical Reports Server (NTRS)

1982-01-01

A 48-page report describes water-heating system, installation (covering collector orientation, mounting, plumbing and wiring), operating instructions and maintenance procedures. Commercial solar-powered water heater system consists of a solar collector, solar-heated-water tank, electrically heated water tank and controls. Analysis of possible hazards from pressure, electricity, toxicity, flammability, gas, hot water and steam are also included.

Disturbance Source Separation in Shear Flows Using Blind Source Separation Methods

NASA Astrophysics Data System (ADS)

Gluzman, Igal; Cohen, Jacob; Oshman, Yaakov

2017-11-01

A novel approach is presented for identifying disturbance sources in wall-bounded shear flows. The method can prove useful for active control of boundary layer transition from laminar to turbulent flow. The underlying idea is to consider the flow state, as measured in sensors, to be a mixture of sources, and to use Blind Source Separation (BSS) techniques to recover the separate sources and their unknown mixing process. We present a BSS method based on the Degenerate Unmixing Estimation Technique. This method can be used to identify any (a priori unknown) number of sources by using the data acquired by only two sensors. The power of the new method is demonstrated via numerical and experimental proofs of concept. Wind tunnel experiments involving boundary layer flow over a flat plate were carried out, in which two hot-wire anemometers were used to separate disturbances generated by disturbance generators such as a single dielectric barrier discharge plasma actuator and a loudspeaker.

Investigations of flowfields found in typical combustor geometries

NASA Technical Reports Server (NTRS)

Lilley, D. G.

1982-01-01

Measurements and computations are being applied to an axisymmetric swirling flow, emerging from swirl vanes at angle phi, entering a large chamber test section via a sudden expansion of various side-wall angles alpha. New features are: the turbulence measurements are being performed on swirling as well as nonswirling flow; and all measurements and computations are also being performed on a confined jet flowfield with realistic downstream blockage. Recent activity falls into three categories: (1) Time-mean flowfield characterization by five-hole pitot probe measurements and by flow visualization; (2) Turbulence measurements by a variety of single- and multi-wire hot-wire probe techniques; and (3) Flowfield computations using the computer code developed during the previous year's research program.

Wire-Cut Electrical Discharge Machinability of Ceramics

DTIC Science & Technology

1987-09-01

20783-1145 23 II. MONITOIIIING AGENCY NAME I ADDRESSI’•I dill••"’’ ,,..... Coroir.,lllnf Olliu) IS. SE:CUitiTY CLASS. (el "’’• ,.,. rt ) Unclassified...8217-’- \\..,... ’-""’’’l.l"’’il ·.. rt ~~\\.o"’ll!r...’liii.~JJIII..a.. •11..·• -~_w._..__...l!IA • a -...w-,.u, a.w .._.._ lll.M .._. ~~ ~~ .:,. ·l...were wire electrical dis- chars•· Mchine.J froa a bulk plec ’’ of hot prearted Grade A. TiB2• A like nuaber were dia110n,t ground fro• the an• bilht of

A rotating hot-wire technique for spatial sampling of disturbed and manipulated duct flows

NASA Technical Reports Server (NTRS)

Wark, C. E.; Nagib, H. M.; Jennings, M. J.

1990-01-01

A duct flow spatial sampling technique, in which an X-wire probe is rotated about the center of a cylindrical test section at a radius equal to one-half that of the test section in order to furnish nearly instantaneous multipoint measurements of the streamwise and azimuthal components, is presently evaluated in view of the control of flow disturbances downstream of various open inlet contractions. The effectiveness of a particular contraction in controlling ingested flow disturbances was ascertained by artificially introducing disturbances upstream of the contractions; control effectiveness if found to be strongly dependent on inlet contraction, with consequences for the reduction of passing-blade frequency noise during gas turbine engine ground testing.

The measurement of shear stress and total heat flux in a nonadiabatic turbulent hypersonic boundary layer

NASA Technical Reports Server (NTRS)

Mikulla, V.; Horstman, C. C.

1975-01-01

Turbulent shear stress and direct turbulent total heat-flux measurements have been made across a nonadiabatic, zero pressure gradient, hypersonic boundary layer by using specially designed hot-wire probes free of strain-gauging and wire oscillation. Heat-flux measurements were in reasonably good agreement with values obtained by integrating the energy equation using measured profiles of velocity and temperature. The shear-stress values deduced from the measurements, by assuming zero correlation of velocity and pressure fluctuations, were lower than the values obtained by integrating the momentum equation. Statistical properties of the cross-correlations are similar to corresponding incompressible measurements at approximately the same momentum-thickness Reynolds number.

Analysis and test results for a molten salt thermal energy storage system

NASA Astrophysics Data System (ADS)

Sterrett, R. H.; Scott, O. L.

A system has been developed to provide low cost thermal energy storage using molten salt. It consists of a hot tank to store the 565 C (1050 F) salt and a cold tank to store the 289 C (550 F) salt. The hot tank uses internal insulation protected by a liner to enable the use of a carbon steel shell for structural support. Due to the lower salt temperature, the cold tank can be a carbon steel shell with external insulation. This paper describes an analytical method used to predict the thermal performance of such systems and presents experimental data from a Subsystem Research Experiment (SRE) conducted by Martin Marietta Aerospace, Solar Energy Systems under contract from Sandia National Laboratories, Livermore, CA. The results from three of the SRE test cases are compared with the STS model results. These are (1) steady state operation, (2) concurrent charging and discharging, and (3) transient cooldown. The temperature differences between the analytical and experimental results were less than 10%. The internally insulated hot tank performed well.

Hot-hole extraction from quantum dot to molecular adsorbate.

PubMed

Singhal, Pallavi; Ghosh, Hirendra N

2015-03-09

Ultrafast thermalized and hot-hole-transfer processes have been investigated in CdSe quantum dot (QD)/catechol composite systems in which hole transfer from photoexcited QDs to the catechols is thermodynamically favorable. A series of catechol derivatives were selected with different electron-donating and -withdrawing groups, and the effect of these groups on hole transfer and charge recombination (CR) dynamics has been investigated. The hole-transfer time was determined using the fluorescence upconversion technique and found to be 2-10 ps depending on the molecular structure of the catechol derivatives. The hot-hole-transfer process was followed after monitoring 2S luminescence of CdSe QDs. Interestingly, hot-hole extraction was observed only in the CdSe/3-methoxycatechol (3-OCH3) composite system owing to the higher electron-donating property of the 3-methoxy group. To confirm the extraction of the hot hole and to monitor the CR reaction in CdSe QD/catechol composite systems, ultrafast transient absorption studies have been carried out. Ultrafast transient-absorption studies show that the bleach recovery kinetics of CdSe QD at the 2S excitonic position is much faster in the presence of 3-OCH3. This faster bleach recovery at the 2S position in CdSe/3-OCH3 suggests hot-hole transfer from CdSe QD to 3-OCH3. CR dynamics in CdSe QD/catechol composite systems was followed by monitoring the excitonic bleach at the 1S position and was found to decrease with free energy of the CR reaction. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Interpretation of energy deposition data from historical operation of the transient test facility (TREAT)

DOE PAGES

DeHart, Mark D.; Baker, Benjamin A.; Ortensi, Javier

2017-07-27

The Transient Test Reactor (TREAT) at Idaho National Laboratory will resume operations in late 2017 after a 23 year hiatus while maintained in a cold standby state. Over that time period, computational power and simulation capabilities have increased substantially and now allow for new multiphysics modeling possibilities that were not practical or feasible for most of TREAT's operational history. Hence the return of TREAT to operational service provides a unique opportunity to apply state-of-the-art software and associated methods in the modeling and simulation of general three-dimensional steady state and kinetic behavior for reactor operation, and for coupling of the coremore » power transient model to experiment simulations. However, measurements taken in previous operations were intended to predict power deposition in experimental samples, with little consideration of three-dimensional core power distributions. Hence, interpretation of data for the purpose of validation of modern methods can be challenging. For the research discussed herein, efforts are described for the process of proper interpretation of data from the most recent calibration experiments performed in the core, the M8 calibration series (M8-CAL). These measurements were taken between 1990 and 1993 using a set of fission wires and test fuel pins to estimate the power deposition that would be produced in fast reactor test fuel pins during the M8 experiment series. Because of the decision to place TREAT into a standby state in 1994, the M8 series of transients were never performed. However, potentially valuable information relevant for validation is available in the M8-CAL measurement data, if properly interpreted. This article describes the current state of the process of recovery of useful data from M8-CAL measurements and quantification of biases and uncertainties to potentially apply to the validation of multiphysics methods.« less

Interpretation of energy deposition data from historical operation of the transient test facility (TREAT)

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeHart, Mark D.; Baker, Benjamin A.; Ortensi, Javier

The Transient Test Reactor (TREAT) at Idaho National Laboratory will resume operations in late 2017 after a 23 year hiatus while maintained in a cold standby state. Over that time period, computational power and simulation capabilities have increased substantially and now allow for new multiphysics modeling possibilities that were not practical or feasible for most of TREAT's operational history. Hence the return of TREAT to operational service provides a unique opportunity to apply state-of-the-art software and associated methods in the modeling and simulation of general three-dimensional steady state and kinetic behavior for reactor operation, and for coupling of the coremore » power transient model to experiment simulations. However, measurements taken in previous operations were intended to predict power deposition in experimental samples, with little consideration of three-dimensional core power distributions. Hence, interpretation of data for the purpose of validation of modern methods can be challenging. For the research discussed herein, efforts are described for the process of proper interpretation of data from the most recent calibration experiments performed in the core, the M8 calibration series (M8-CAL). These measurements were taken between 1990 and 1993 using a set of fission wires and test fuel pins to estimate the power deposition that would be produced in fast reactor test fuel pins during the M8 experiment series. Because of the decision to place TREAT into a standby state in 1994, the M8 series of transients were never performed. However, potentially valuable information relevant for validation is available in the M8-CAL measurement data, if properly interpreted. This article describes the current state of the process of recovery of useful data from M8-CAL measurements and quantification of biases and uncertainties to potentially apply to the validation of multiphysics methods.« less

Characterization of Unsteady Flow Structures Around Tandem Cylinders for Component Interaction Studies in Airframe Noise

NASA Technical Reports Server (NTRS)

Jenkins, Luther N.; Khorrami, Mehdi R.; Choudhari, Meelan M.; McGinley, Catherine B.

2005-01-01

A joint computational and experimental study has been performed at NASA Langley Research Center to investigate the unsteady flow generated by the components of an aircraft landing gear system. Because the flow field surrounding a full landing gear is so complex, the study was conducted on a simplified geometry consisting of two cylinders in tandem arrangement to isolate and characterize the pertinent flow phenomena. This paper focuses on the experimental effort where surface pressures, 2-D Particle Image Velocimetry, and hot-wire anemometry were used to document the flow interaction around the two cylinders at a Reynolds Number of 1.66 x 10(exp 5), based on cylinder diameter, and cylinder spacing-todiameter ratios, L/D, of 1.435 and 3.70. Transition strips were applied to the forward cylinder to produce a turbulent boundary layer upstream of the flow separation. For these flow conditions and L/D ratios, surface pressures on both the forward and rear cylinders show the effects of L/D on flow symmetry, base pressure, and the location of flow separation and attachment. Mean velocities and instantaneous vorticity obtained from the PIV data are used to examine the flow structure between and aft of the cylinders. Shedding frequencies and spectra obtained using hot-wire anemometry are presented. These results are compared with unsteady, Reynolds-Averaged Navier-Stokes (URANS) computations for the same configuration in a companion paper by Khorrami, Choudhari, Jenkins, and McGinley (2005). The experimental dataset produced in this study provides information to better understand the mechanisms associated with component interaction noise, develop and validate time-accurate computer methods used to calculate the unsteady flow field, and assist in modeling of the radiated noise from landing gears.

Electrically isolated, high melting point, metal wire arrays and method of making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Simpson, John T.; Cunningham, Joseph P.; D'Urso, Brian R.

2016-01-26

A method of making a wire array includes the step of providing a tube of a sealing material and having an interior surface, and positioning a wire in the tube, the wire having an exterior surface. The tube is heated to soften the tube, and the softened tube is drawn and collapsed by a mild vacuum to bring the interior surface of the tube into contact with the wire to create a coated wire. The coated wires are bundled. The bundled coated wires are heated under vacuum to fuse the tube material coating the wires and create a fused rodmore » with a wire array embedded therein. The fused rod is cut to form a wire array. A wire array is also disclosed.« less

Simulation and Experimental Study on Thermal Conductivity of [EMIM][DEP] + H_2 O + SWCNTs Nanofluids as a New Working Pairs

NASA Astrophysics Data System (ADS)

Li, Chang; Zhao, Zongchang; Zhang, Xiaodong; Li, Tianyu

2018-03-01

In this paper, the single-wall carbon nanotubes (SWCNTs) were dispersed into ionic liquid, 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM][DEP]), and its aqueous solution [EMIM][DEP](1) + H2O(2) to enhance the thermal conductivity of base liquids, which will be the promising working pairs for absorption heat pumps and refrigerators. The enhancement effects on thermal conductivity were studied by experiment and molecular dynamic simulation (MD) methods. The thermal conductivities of [EMIM][DEP] + SWCNTs (INF) and [EMIM][DEP](1) + H2O(2) + SWCNT(SNF) both with SWCNT mass fraction of 0.5, 1, and 2 (wt%) were measured by transient hot-wire method. The results indicate that the enhancement ratio of thermal conductivity of INF, and SNF can approach 1.30 when SWCNT is 2 (wt%). Moreover, SWCNTs has a higher enhancement ratio than multi-wall carbon nanotubes (MWCNTs). Density and thermal conductivity of [EMIM][DEP], [EMIM][DEP](1) + H2O(2), INF and SNF systems, together with self-diffusion coefficients of [EMIM]+, [DEP]-, [EMIM][DEP] and water in solution [EMIM][DEP](1) + H2O(2), were investigated by MD simulations. The results indicate that the maximum relative error between the simulated and experimental densities is about 2 %, and the simulated self-diffusion coefficient of [EMIM][DEP] is in the order of magnitude of 10^{-11} m2\\cdot s^{-1}. The average relative deviation for the simulated thermal conductivity of [EMIM][DEP](1) + H2O(2), INF and SNF from experimental ones are 23.57 %, 5 %, and 5 %, respectively. In addition, the contributions of kinetic energy, potential energy, and virial and partial enthalpy terms to thermal conductivity were also calculated. The results indicate that virial term's contribution to thermal conductivity is the maximum, which accounts for 75 % to 80 % of total thermal conductivity.

46 CFR 28.865 - Wiring methods and materials.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 1 2010-10-01 2010-10-01 false Wiring methods and materials. 28.865 Section 28.865... FISHING INDUSTRY VESSELS Aleutian Trade Act Vessels § 28.865 Wiring methods and materials. (a) All cable... terminals is not more than 10 percent. (c) Cable and wiring not serving equipment in high risk fire areas...

Current Approach in Surface Plasmons for Thin Film and Wire Array Solar Cell Applications

PubMed Central

Zhou, Keya; Guo, Zhongyi; Liu, Shutian; Lee, Jung-Ho

2015-01-01

Surface plasmons, which exist along the interface of a metal and a dielectric, have been proposed as an efficient alternative method for light trapping in solar cells during the past ten years. With unique properties such as superior light scattering, optical trapping, guide mode coupling, near field concentration, and hot-electron generation, metallic nanoparticles or nanostructures can be tailored to a certain geometric design to enhance solar cell conversion efficiency and to reduce the material costs. In this article, we review current approaches on different kinds of solar cells, such as crystalline silicon (c-Si) and amorphous silicon (a-Si) thin film solar cells, organic solar cells, nanowire array solar cells, and single nanowire solar cells. PMID:28793457

Flow visualization of lateral jet injection into swirling crossflow

NASA Technical Reports Server (NTRS)

Ferrell, G. B.; Aoki, K.; Lilley, D. G.

1985-01-01

Flow visualization experiments have been conducted to characterize the time-mean flowfield of a deflected turbulent jet in a confining cylindrical crossflow. Jet-to-crossflow velocity ratios of 2, 4, and 6 were investigated, under crossflow inlet swirler vane angles of 0 (swirler removed), 45 and 70 degrees. Smoke, neutrally-buoyant helium-filled soap bubbles, and multi-spark flow visualization were employed to highlight interesting features of the deflected jet, as well as the trajectory and spread pattern of the jet. Gross flowfield characterization was obtained for a range of lateral jet-to-crossflow velocity ratios and a range of inlet swirl strengths in the main flow. The flow visualization results agree well with the measurements obtained elsewhere with the six-orientation single hot-wire method.

M-shell resolved high-resolution X-ray spectroscopic study of transient matter evolution driven by hot electrons in kJ-laser produced plasmas

NASA Astrophysics Data System (ADS)

Condamine, F. P.; Šmíd, M.; Renner, O.; Dozières, M.; Thais, F.; Angelo, P.; Rosmej, F. B.

2017-03-01

Hot electrons represent a key subject for high intensity laser produced plasmas and atomic physics. Simulations of the radiative properties indicate a high sensitivity to hot electrons, that in turn provides the possibility for their detailed characterization by high-resolution spectroscopic methods. Of particular interest is X-ray spectroscopy due to reduced photo-absorption in dense matter and their efficient generation by hot electrons (inner-shell ionization/excitation). Here, we report on an experimental campaign conducted at the ns, kJ laser facility PALS at Prague in Czech Republic. Thin copper foils have been irradiated with 1ω pulses. Two spherically bent quartz Bragg crystal spectrometers with high spectral (λ/Δλ > 5000) and spatial resolutions (Δx = 30µm) have been set up simultaneously to achieve a high level of confidence for the complex Kα emission group. In particular, this group, which shows a strong overlap between lines, can be resolved in several substructures. Furthermore, an emission on the red wing of the Kα2 transition (λ = 1.5444A) could be identified with Hartree-Fock atomic structure calculations. We discuss possible implications for the analysis of non-equilibrium phenomena and present first simulations.

Theoretical evaluation of burns to the human respiratory tract due to inhalation of hot gas in the early stage of fires.

PubMed

Lv, Yong-Gang; Liu, Jing; Zhang, Jun

2006-06-01

A transient two-dimensional mathematical model for heat and water vapor transport across the respiratory tract of human body was established and applied to predict the thermal impact of inhaled hot gas to the nasal tissues during the early stage of fires. Influences of individual's physiological status and environment variables were comprehensively investigated through numerical calculations. Burn evaluation was performed using the classical Henriques model to predict the time for thermal injury to occur. It was shown that decreasing the air velocity and increasing the respiratory rate is helpful to minimize the burn over the respiratory tract. The effect of relative humidity of surrounding dry hot air could be ignored in predicting burns for short duration exposures. Due to evaporation cooling on the mucousal membrane, the burn often occurs at certain positions underneath the skin of the tract near the inlet of the respiratory tract. Most of the tissues near the surface suffer injury immediately after exposure to fire, while in the deeper tissues, serious damage occurs after a relatively longer time period. The method presented in this paper may suggest a valuable approach to theoretically evaluate the injury of hot air to the human respiratory tract under various fire situations.

Energetic Particle Sounding of the Magnetopause Deformed by Hot Flow Anomaly

NASA Astrophysics Data System (ADS)

Zhao, L.; Zong, Q.; Zhang, H.

2017-12-01

Hot flow anomalies (HFAs), which are frequently observed near Earth's bow shock, are phenomena resulting from the interaction between interplanetary discontinuities and Earth's bow shock. Such transient phenomena upstream the bow shock can cause significant deformation of the bow shock and the magnetosphere, generating traveling convection vortices, field-aligned currents, and ULF waves in the Earth's magnetosphere. A large HFA was observed by MMS on November 19, 2015, lasting about 16 minutes. In this study, energetic particle sounding method with high time resolution (150 ms) Fast Plasma Investigation (FPI) data is used to determine the deformed magnetopause distances, orientations, and structures in the interval when MMS pass through the deformed magnetopause. The energetic particle sounding result from single MMS satellite for every moment in the interval when the distance from the magnetopause to the satellite is less than two proton gyro radii shows the profile of the deformed magnetopause.

BEST3D user's manual: Boundary Element Solution Technology, 3-Dimensional Version 3.0

NASA Technical Reports Server (NTRS)

1991-01-01

The theoretical basis and programming strategy utilized in the construction of the computer program BEST3D (boundary element solution technology - three dimensional) and detailed input instructions are provided for the use of the program. An extensive set of test cases and sample problems is included in the manual and is also available for distribution with the program. The BEST3D program was developed under the 3-D Inelastic Analysis Methods for Hot Section Components contract (NAS3-23697). The overall objective of this program was the development of new computer programs allowing more accurate and efficient three-dimensional thermal and stress analysis of hot section components, i.e., combustor liners, turbine blades, and turbine vanes. The BEST3D program allows both linear and nonlinear analysis of static and quasi-static elastic problems and transient dynamic analysis for elastic problems. Calculation of elastic natural frequencies and mode shapes is also provided.

Space Shuttle main engine product improvement

NASA Technical Reports Server (NTRS)

Lucci, A. D.; Klatt, F. P.

1985-01-01

The current design of the Space Shuttle Main Engine has passed 11 certification cycles, amassed approximately a quarter million seconds of engine test time in 1200 tests and successfully launched the Space Shuttle 17 times of 51 engine launches through May 1985. Building on this extensive background, two development programs are underway at Rocketdyne to improve the flow of hot gas through the powerhead and evaluate the changes to increase the performance margins in the engine. These two programs, called Phase II+ and Technology Test Bed Precursor program are described. Phase II+ develops a two-tube hot-gas manifold that improves the component environment. The Precursor program will evaluate a larger throat main combustion chamber, conduct combustion stability testing of a baffleless main injector, fabricate an experimental weld-free heat exchanger tube, fabricate and test a high pressure oxidizer turbopump with an improved inlet, and develop and test methods for reducing temperature transients at start and shutdown.

Method of fabricating a homogeneous wire of inter-metallic alloy

DOEpatents

Ohriner, Evan Keith; Blue, Craig Alan

2001-01-01

A method for fabricating a homogeneous wire of inter-metallic alloy comprising the steps of providing a base-metal wire bundle comprising a metal, an alloy or a combination thereof; working the wire bundle through at least one die to obtain a desired dimension and to form a precursor wire; and, controllably heating the precursor wire such that a portion of the wire will become liquid while simultaneously maintaining its desired shape, whereby substantial homogenization of the wire occurs in the liquid state and additional homogenization occurs in the solid state resulting in a homogenous alloy product.

Considerations in development and implementation of elasto-viscoplastic constitutive model for high temperature applications

NASA Technical Reports Server (NTRS)

Riff, Richard

1988-01-01

The prediction of inelastic behavior of metallic materials at elevated temperatures has increased in importance in recent years. The operating conditions within the hot section of a rocket motor or a modern gas turbine engine present an extremely harsh thermomechanical environment. Large thermal transients are induced each time the engine is started or shut down. Additional thermal transients from an elevated ambient occur whenever the engine power level is adjusted to meet flight requirements. The structural elements employed in such hot sections, as well as any engine components located therein, must be capable of withstanding such extreme conditions. Failure of a component would, due to the critical nature of the hot section, lead to an immediate and catastrophic loss in power. Consequently, assuring satisfactory long term performance for such components is a major concern. Nonisothermal loading of structures often causes excursion of stress well into the inelastic range. Moreover, the influence of geometry changes on the response is also significant in most cases. Therefore, both material and geometric nonlinear effects are considered.

Numerical analysis of steady and transient natural convection in an enclosed cavity

NASA Astrophysics Data System (ADS)

Mehedi, Tanveer Hassan; Tahzeeb, Rahat Bin; Islam, A. K. M. Sadrul

2017-06-01

The paper presents the numerical simulation of natural convection heat transfer of air inside an enclosed cavity which can be helpful to find out the critical width of insulation in air insulated walls seen in residential buildings and industrial furnaces. Natural convection between two walls having different temperatures have been simulated using ANSYS FLUENT 12.0 in both steady and transient conditions. To simulate different heat transfer and fluid flow conditions, Rayleigh number ranging from 103 to 105 has been maintained (i.e. Laminar flow.) In case of steady state analysis, the CFD predictions were in very good agreement with the reviewed literature. Transient simulation process has been performed by using User Defined Functions, where the temperature of the hot wall varies with time linearly. To obtain and compare the heat transfer properties, Nusselt number has been calculated at the hot wall at different conditions. The buoyancy driven flow characteristics have been investigated by observing the flow pattern in a graphical manner. The characteristics of the system at different temperature differences between the wall has been observed and documented.

About plasma points' generation in Z-pinch

NASA Astrophysics Data System (ADS)

Afonin, V. I.; Potapov, A. V.; Lazarchuk, V. P.; Murugov, V. M.; Senik, A. V.

1997-05-01

The streak tube study results (at visible and x-ray ranges) of dynamics of fast Z-pinch formed at explosion of metal wire in diode of high current generator are presented. Amplitude of current in the load reached ˜180 kA at increase time ˜50 ns. The results' analysis points to capability of controlling hot plasma points generation process in Z-pinch.

EBW's and EFI's: The other electric detonators

NASA Technical Reports Server (NTRS)

Varosh, Ron

1994-01-01

Exploding Bridgewire Detonators (EBW) and Exploding Foil Initiators (EFI) which were originally developed for military applications, have found numerous uses in the non-military commercial market while still retaining their military uses. While not as common as the more familiar hot wire initiators, EBW's and EFI's have definite advantages in certain applications. These advantages, and disadvantages, are discussed for typical designs.

Study of Silicidation Process of Tungsten Catalyzer during Silicon Film Deposition in Catalytic Chemical Vapor Deposition

NASA Astrophysics Data System (ADS)

Honda, Kazuhiro; Ohdaira, Keisuke; Matsumura, Hideki

2008-05-01

In catalytic chemical vapor deposition (Cat-CVD), often called hot-wire CVD, source gases are decomposed by catalytic cracking reactions with heated catalyzing metal wires. In the case of silicon (Si) film deposition, such metal wires are often converted to silicide, which shortens the lifetime of catalyzing wires. As a catalyzer, tungsten (W) is widely used. Thus, the process of silicidation of a W catalyzer at temperatures over 1650 °C, which is the temperature used in Cat-CVD for Si film deposition, was studied extensively in various experiments. It is found that two phases of tungsten-silicide, WSi2 and W5Si3, are formed at this temperature, and that the radiation emissivity of WSi2 is 1.2 to 1.7 times higher than that of W5Si3 and pure W. The increase of surface emissivity due to the formation of WSi2 decreases the catalyzer surface temperature which induces further growth of the tungsten-silicide layer. It is also found that the suppression of WSi2 formation by elevating catalyzer temperatures over 1750 °C is a key to extending the lifetime of the W catalyzer in Cat-CVD.

Fixed-angle plate osteosynthesis of the patella - an alternative to tension wiring?

PubMed

Wild, M; Eichler, C; Thelen, S; Jungbluth, P; Windolf, J; Hakimi, M

2010-05-01

The goal of this study is carry out a biomechanical evaluation of the stability of a bilateral, polyaxial, fixed-angle 2.7 mm plate system specifically designed for use on the patella. The results of this approach are then compared to the two currently most commonly used surgical techniques for patella fractures: modified anterior tension wiring with K-wires and cannulated lag screws with anterior tension wiring. A transient biomechanical analysis determining material failure points of all osteosyntheses were conducted on 21 identical left polyurethane foam patellae, which were osteotomized horizontally. Evaluated were load (N), displacement (mm) and run-time (s) as well as elastic modulus (MPa), tensile strength (MPa) and strain at failure (%). With a maximum load capacity of 2396 (SD 492) N, the fixed-angle plate proved to be significantly stronger than the cannulated lag screws with anterior tension wiring (1015 (SD 246) N) and the modified anterior tension wiring (625 (SD 84.9) N). The fixed-angle plate displayed significantly greater stiffness and lower fracture gap dehiscence than the other osteosyntheses. Additionally, osteosynthesis deformation was found to be lower for the fixed-angle plate. A bilateral fixed-angle plate was the most rigid and stable osteosynthesis for horizontal patella fractures with the least amount of fracture gap dehiscence. Further biomechanical trials performed under cycling loading with fresh cadaver specimen should be done to figure out if a fixed-angle plate may be an alternative in the surgical treatment of patella fractures. Copyright 2009 Elsevier Ltd. All rights reserved.

An investigation of the flow characteristics in the blade endwall corner region

NASA Technical Reports Server (NTRS)

Hazarika, Birinchi K.; Raj, Rishi S.

1987-01-01

Studies were undertaken to determine the structure of the flow in the blade end wall corner region simulated by attaching two uncambered airfoils on either side of a flat plate with a semicircular leading edge. Detailed measurements of the corner flow were obtained with conventional pressure probes, hot wire anemometry, and flow visualization. The mean velocity profiles and six components of the Reynolds stress tensor were obtained with an inclined single sensor hot wire probe whereas power spectra were obtained with a single sensor oriented normal to the flow. Three streamwise vortices were identified based on the surface streamlines, distortion of total pressure profiles, and variation of mean velocity components in the corner. A horseshoe vortex formed near the leading edge of the airfoil. Within a short distance downstream, a corner vortex was detected between the horseshoe vortex and the surfaces forming the corner. A third vortex was formed at the rear portion of the corner between the corner vortex and the surface of the flat plate. Turbulent shear stress and production of turbulence are negligibly small. A region of negative turbulent shear stress was also observed near the region of low turbulence intensity from the vicinity of the flat plate.

Dynamic properties of hot-wire anemometric measurement circuits in the aspect of measurements in mine conditions / Właściwości dynamiczne termoanemometrycznych układów pomiarowych w aspekcie pomiarów w warunkach kopalnianych

NASA Astrophysics Data System (ADS)

Jamróz, Paweł; Ligęza, Paweł; Socha, Katarzyna

2012-12-01

The use of measurement apparatus under conditions which differ significantly from those under which the apparatus was adjusted carries the risk of altering the previously determined measurement characteristics. This is of special concern in the case of apparatus which is sensitive to external measurement conditions. Advanced measurement systems are equipped with algorithms which allow the negative effect of unstable environmental conditions on their static characteristics to be compensated for. Meanwhile, the problem of altered dynamic properties of such systems is often neglected. This paper presents a model study in which the effect of variable operational conditions on dynamic response of hot-wire anemometric measurement system in the case of simulated mine flows was investigated. A mathematical model of measurement system able to compensate the negative effect of changes in flow velocity and configuration of measurement apparatus itself on its dynamic properties was developed and investigated. Based on conducted experiments, we have developed an automatic regulation algorithm enabling the transmission band of measurement apparatus to be optimized for measurement conditions prevailing in mine environment.

Composite wire microelectrode and method of making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isaacs, Hugh S.; Aldykiewicz, Jr., Antonio J.

1996-12-03

A composite wire microelectrode for making electro-chemical measurements, and method of making same. The microelectrode includes an inner conductive sensing wire and an outer tube that is oxidized to form a dielectric, self-healing oxide layer around the sensing wire.

Transient thermal characteristics of high-temperature SiC power module enhanced with Al-bump technology

NASA Astrophysics Data System (ADS)

Tanisawa, Hidekazu; Kato, Fumiki; Koui, Kenichi; Sato, Shinji; Watanabe, Kinuyo; Takahashi, Hiroki; Murakami, Yoshinori; Sato, Hiroshi

2018-04-01

In this paper, we demonstrate a mounting technology that improves the tolerance to transient power loss by adding a heat capacity near the device. Silicon carbide (SiC) power devices can operate at high temperatures, up to 250 °C, at which silicon (Si) power devices cannot. Therefore, it is possible to allow a large temperature difference between the device and ambient air. Thus, the size of a power converter equipped with an SiC power module is reduced by simplifying the cooling system. The temperature of the power module is important not only in the steady state, but in transient loads as well. Therefore, we developed the Al-bump flip-chip mounting technology to increase heat capacity near the device. With this proposed structure, the heat capacity per device increased by 1.7% compared with the total heat capacity of the conventional structure using wire bonding. The reduction in transient thermal impedance is observed from 0.003 to 3 s, and we confirmed that the transient thermal impedance is reduced very efficiently by 15% at the maximum, compared with the conventional structure.

A correction method of the anode wire modulation for 2D MWPCs detector

NASA Astrophysics Data System (ADS)

Wen, Z. W.; Qi, H. R.; Zhang, Y. L.; Wang, H. Y.; Liu, L.; Li, Y. H.

2018-04-01

The linearity performance of 2D Multi-Wire Proportional Chambers (MWPCs) detector across the anode wires is modulated by the discrete anode wires. A MWPCs dectector with the 2 mm anode wire spacing was developed to study the anode wire modulation effect. The 2D lineartity performance was measured with a 55Fe source which was moved by a electric mobile platform. The experimental results show that the deviation of the measured position depends upon the incident position in the axis across the anode wires and the curve between the measured position and the incident position is consistent with the sine function whose period is equal to the anode wire spacing. A correction method of the measured position across the anode wire direction was obtained by fitting the curve between the measured position and the incident position. The non-linearity of the measured position across the anode wire direction is reduced about 0.085% and the imaging capability is obviously improved after the data is modified by the correction method.

Rapidly Evolving Transients in the Dark Energy Survey

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pursiainen, M.; et al.

We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme. These events are characterized by fast light curve evolution (rise to peak inmore » $$\\lesssim 10$$ d and exponential decline in $$\\lesssim30$$ d after peak). We discovered 72 events, including 37 transients with a spectroscopic redshift from host galaxy spectral features. The 37 events increase the total number of rapid optical transients by more than factor of two. They are found at a wide range of redshifts ($0.05M_\\mathrm{g}>-22.25$$). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot ($$T\\approx10000-30000$$ K) and large ($$R\\approx 10^{14}-2\\cdot10^{15}$$ cm) at peak, and generally expand and cool in time, though some events show evidence for a receding photosphere with roughly constant temperature. Spectra taken around peak are dominated by a blue featureless continuum consistent with hot, optically thick ejecta. We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova (CCSNe), we conclude that current models for such a scenario might need an additional power source to describe the exponential decline. We find these transients tend to favor star-forming host galaxies, which could be consistent with a core-collapse origin. However, more detailed modeling of the light curves is necessary to determine their physical origin.« less

Modified coaxial wire method for measurement of transfer impedance of beam position monitors

NASA Astrophysics Data System (ADS)

Kumar, Mukesh; Babbar, L. K.; Deo, R. K.; Puntambekar, T. A.; Senecha, V. K.

2018-05-01

The transfer impedance is a very important parameter of a beam position monitor (BPM) which relates its output signal with the beam current. The coaxial wire method is a standard technique to measure transfer impedance of the BPM. The conventional coaxial wire method requires impedance matching between coaxial wire and external circuits (vector network analyzer and associated cables). This paper presents a modified coaxial wire method for bench measurement of the transfer impedance of capacitive pickups like button electrodes and shoe box BPMs. Unlike the conventional coaxial wire method, in the modified coaxial wire method no impedance matching elements have been used between the device under test and the external circuit. The effect of impedance mismatch has been solved mathematically and a new expression of transfer impedance has been derived. The proposed method is verified through simulation of a button electrode BPM using cst studio suite. The new method is also applied to measure transfer impedance of a button electrode BPM developed for insertion devices of Indus-2 and the results are also compared with its simulations. Close agreement between measured and simulation results suggests that the modified coaxial wire setup can be exploited for the measurement of transfer impedance of capacitive BPMs like button electrodes and shoe box BPM.

The Wire-Grasping Method as a New Technique for Forceps Biopsy of Biliary Strictures: A Prospective Randomized Controlled Study of Effectiveness

PubMed Central

Yamashita, Yasunobu; Ueda, Kazuki; Kawaji, Yuki; Tamura, Takashi; Itonaga, Masahiro; Yoshida, Takeichi; Maeda, Hiroki; Magari, Hirohito; Maekita, Takao; Iguchi, Mikitaka; Tamai, Hideyuki; Ichinose, Masao; Kato, Jun

2016-01-01

Background/Aims Transpapillary forceps biopsy is an effective diagnostic technique in patients with biliary stricture. This prospective study aimed to determine the usefulness of the wire-grasping method as a new technique for forceps biopsy. Methods Consecutive patients with biliary stricture or irregularities of the bile duct wall were randomly allocated to either the direct or wire-grasping method group. In the wire-grasping method, forceps in the duodenum grasps a guide-wire placed into the bile duct beforehand, and then, the forceps are pushed through the papilla without endoscopic sphincterotomy. In the direct method, forceps are directly pushed into the bile duct alongside a guide-wire. The primary endpoint was the success rate of obtaining specimens suitable for adequate pathological examination. Results In total, 32 patients were enrolled, and 28 (14 in each group) were eligible for analysis. The success rate was significantly higher using the wire-grasping method than the direct method (100% vs 50%, p=0.016). Sensitivity and accuracy for the diagnosis of cancer were comparable in patients with the successful procurement of biopsy specimens between the two methods (91% vs 83% and 93% vs 86%, respectively). Conclusions The wire-grasping method is useful for diagnosing patients with biliary stricture or irregularities of the bile duct wall. PMID:27021502

Small Hot Jet Acoustic Rig Validation

NASA Technical Reports Server (NTRS)

Brown, Cliff; Bridges, James

2006-01-01

The Small Hot Jet Acoustic Rig (SHJAR), located in the Aeroacoustic Propulsion Laboratory (AAPL) at the NASA Glenn Research Center in Cleveland, Ohio, was commissioned in 2001 to test jet noise reduction concepts at low technology readiness levels (TRL 1-3) and develop advanced measurement techniques. The first series of tests on the SHJAR were designed to prove its capabilities and establish the quality of the jet noise data produced. Towards this goal, a methodology was employed dividing all noise sources into three categories: background noise, jet noise, and rig noise. Background noise was directly measured. Jet noise and rig noise were separated by using the distance and velocity scaling properties of jet noise. Effectively, any noise source that did not follow these rules of jet noise was labeled as rig noise. This method led to the identification of a high frequency noise source related to the Reynolds number. Experiments using boundary layer treatment and hot wire probes documented this noise source and its removal, allowing clean testing of low Reynolds number jets. Other tests performed characterized the amplitude and frequency of the valve noise, confirmed the location of the acoustic far field, and documented the background noise levels under several conditions. Finally, a full set of baseline data was acquired. This paper contains the methodology and test results used to verify the quality of the SHJAR rig.

Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy

NASA Astrophysics Data System (ADS)

Guo, Zhi; Wan, Yan; Yang, Mengjin; Snaider, Jordan; Zhu, Kai; Huang, Libai

2017-04-01

The Shockley-Queisser limit for solar cell efficiency can be overcome if hot carriers can be harvested before they thermalize. Recently, carrier cooling time up to 100 picoseconds was observed in hybrid perovskites, but it is unclear whether these long-lived hot carriers can migrate long distance for efficient collection. We report direct visualization of hot-carrier migration in methylammonium lead iodide (CH3NH3PbI3) thin films by ultrafast transient absorption microscopy, demonstrating three distinct transport regimes. Quasiballistic transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers transport distance that could overcome grain boundaries. The nonequilibrium transport persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport limit. These results suggest potential applications of hot-carrier devices based on hybrid perovskites.

Parallel-wire grid assembly with method and apparatus for construction thereof

DOEpatents

Lewandowski, E.F.; Vrabec, J.

1981-10-26

Disclosed is a parallel wire grid and an apparatus and method for making the same. The grid consists of a generally coplanar array of parallel spaced-apart wires secured between metallic frame members by an electrically conductive epoxy. The method consists of continuously winding a wire about a novel winding apparatus comprising a plurality of spaced-apart generally parallel spindles. Each spindle is threaded with a number of predeterminedly spaced-apart grooves which receive and accurately position the wire at predetermined positions along the spindle. Overlying frame members coated with electrically conductive epoxy are then placed on either side of the wire array and are drawn together. After the epoxy hardens, portions of the wire array lying outside the frame members are trimmed away.

Parallel-wire grid assembly with method and apparatus for construction thereof

DOEpatents

Lewandowski, Edward F.; Vrabec, John

1984-01-01

Disclosed is a parallel wire grid and an apparatus and method for making the same. The grid consists of a generally coplanar array of parallel spaced-apart wires secured between metallic frame members by an electrically conductive epoxy. The method consists of continuously winding a wire about a novel winding apparatus comprising a plurality of spaced-apart generally parallel spindles. Each spindle is threaded with a number of predeterminedly spaced-apart grooves which receive and accurately position the wire at predetermined positions along the spindle. Overlying frame members coated with electrically conductive epoxy are then placed on either side of the wire array and are drawn together. After the epoxy hardens, portions of the wire array lying outside the frame members are trimmed away.

Thin wire pointing method

NASA Technical Reports Server (NTRS)

Green, G.; Mattauch, R. J. (Inventor)

1983-01-01

A method is described for forming sharp tips on thin wires, in particular phosphor bronze wires of diameters such as one-thousandth inch used to contact micron size Schottky barrier diodes, which enables close control of tip shape and which avoids the use of highly toxic solutions. The method includes dipping an end of a phosphor bronze wire into a dilute solution of sulfamic acid and applying a current through the wire to electrochemically etch it. The humidity in the room is controlled to a level of less than 50%, and the voltage applied between the wire and another electrode in the solutions is a half wave rectified voltage. The current through the wire is monitored, and the process is stopped when the current falls to a predetermined low level.

Visualization and imaging methods for flames in microgravity

NASA Technical Reports Server (NTRS)

Weiland, Karen J.

1993-01-01

The visualization and imaging of flames has long been acknowledged as the starting point for learning about and understanding combustion phenomena. It provides an essential overall picture of the time and length scales of processes and guides the application of other diagnostics. It is perhaps even more important in microgravity combustion studies, where it is often the only non-intrusive diagnostic measurement easily implemented. Imaging also aids in the interpretation of single-point measurements, such as temperature, provided by thermocouples, and velocity, by hot-wire anemometers. This paper outlines the efforts of the Microgravity Combustion Diagnostics staff at NASA Lewis Research Center in the area of visualization and imaging of flames, concentrating on methods applicable for reduced-gravity experimentation. Several techniques are under development: intensified array camera imaging, and two-dimensional temperature and species concentrations measurements. A brief summary of results in these areas is presented and future plans mentioned.

Vision-based surface defect inspection for thick steel plates

NASA Astrophysics Data System (ADS)

Yun, Jong Pil; Kim, Dongseob; Kim, KyuHwan; Lee, Sang Jun; Park, Chang Hyun; Kim, Sang Woo

2017-05-01

There are several types of steel products, such as wire rods, cold-rolled coils, hot-rolled coils, thick plates, and electrical sheets. Surface stains on cold-rolled coils are considered defects. However, surface stains on thick plates are not considered defects. A conventional optical structure is composed of a camera and lighting module. A defect inspection system that uses a dual lighting structure to distinguish uneven defects and color changes by surface noise is proposed. In addition, an image processing algorithm that can be used to detect defects is presented in this paper. The algorithm consists of a Gabor filter that detects the switching pattern and employs the binarization method to extract the shape of the defect. The optics module and detection algorithm optimized using a simulator were installed at a real plant, and the experimental results conducted on thick steel plate images obtained from the steel production line show the effectiveness of the proposed method.

Composite wire microelectrode and method of making same

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isaacs, H.S.; Aldykiewicz, A.J. Jr.

1996-12-03

A composite wire microelectrode for making electro-chemical measurements, and method of making same, are disclosed. The microelectrode includes an inner conductive sensing wire and an outer tube that is oxidized to form a dielectric, self-healing oxide layer around the sensing wire. 4 figs.

Quench dynamics of the Josephson current in a topological Josephson junction

NASA Astrophysics Data System (ADS)

Sun, Dihao; Liu, Jie

2018-01-01

The 4 π -periodic Josephson effect is a distinguishing feature of a topological Josephson junction. However, stringent conditions make it hard to observe in experiments. In this work, we study the transient transport properties in a topological Josephson junction numerically. We show that the 4 π Josephson current can be sustained under nonequilibrium conditions. The properties of the Josephson current are analyzed for different conditions and three main regimes are identified. First, when both the superconducting wires of the Josephson junction lie in the topologically nontrivial region, a 4 π Josephson current can appear upon suddenly applying a dc voltage. Second, when one superconducting wire lies in the trivial region, while the other wire lies in the nontrivial region, the Josephson current is 2 π periodic but the component of the higher-order Josephson current increases. Third, when both wires lie in the trivial region, a stable 2 π Josephson current is observed. Most importantly, the fractional Josephson effect is fragile in the presence of disorder. Hence experiments should be designed carefully to eliminate the effect of disorder. These results could be helpful to optimize fine-tuning of the experimental parameters to observe the 4 π -periodic Josephson current in a topological Josephson junction.

Science and Technology Review June 2006

DOE Office of Scientific and Technical Information (OSTI.GOV)

Radousky, H

2006-04-20

This month's issue has the following articles: (1) Maintaining Excellence through Intellectual Vitality--Commentary by Cherry A. Murray; (2) Next-Generation Scientists and Engineers Tap Lab's Resources--University of California Ph.D. candidates work with Livermore scientists and engineers to conduct fundamental research as part of their theses; (3) Adaptive Optics Provide a Clearer View--The Center for Adaptive Optics is sharpening the view of celestial objects and retinal cells; (4) Wired on the Nanoscale--A Lawrence Fellow at Livermore is using genetically engineered viruses to create nanostructures such as tiny gold wires; and (5) Too Hot to Handle--Livermore scientists couple carbon-cycle and climate models tomore » predict the global effects of depleting Earth's fossil-fuel supply.« less

Fluctuation diagrams for hot-wire anemometry in subsonic compressible flows

NASA Technical Reports Server (NTRS)

Stainback, P. C.; Nagabushana, K. A.

1991-01-01

The concept of using 'fluctuation diagrams' for describing basic fluctuations in compressible flows was reported by Kovasznay in the 1950's. The application of this technique, for the most part, was restricted to supersonic flows. Recently, Zinovev and Lebiga published reports where they considered the fluctuation diagrams in subsonic compressible flows. For the above studies, the velocity and density sensitivities of the heated wires were equal. However, there are considerable data, much taken in the 1950's, which indicate that under some conditions the velocity and density sensitivities are not equal in subsonic compressible flows. Therefore, possible fluctuation diagrams are described for the cases where the velocity and density sensitivities are equal and the more general cases where they are unequal.

Hα features with hot onsets. I. Ellerman bombs

NASA Astrophysics Data System (ADS)

Rutten, R. J.

2016-05-01

Ellerman bombs are transient brightenings of the wings of the Balmer lines that uniquely mark reconnection in the solar photosphere. They are also bright in strong Ca II and ultraviolet lines and in ultraviolet continua, but they are not visible in the optical continuum and the Na I D and Mg I b lines. These discordant visibilities invalidate all published Ellerman bomb modeling. I argue that the assumption of Saha-Boltzmann lower-level populations is informative to estimate bomb-onset opacities for these diverse diagnostics, even and especially for Hα, and employ such estimates to gauge the visibilities of Ellerman bomb onsets in all of them. They constrain Ellerman bomb formation to temperatures 10 000-20 000 K and hydrogen densities around 1015 cm-3. Similar arguments likely hold for Hα visibility in other transient phenomena with hot and dense onsets.

[Properties of NiTi wires with direct electric resistance heat treatment method in three-point bending tests].

PubMed

Wang, Hong-mei; Wang, Bang-kang; Ren, Chao-chao; Bai, Yu-xing

2011-03-01

To investigate the mechanical properties of Ni-Ti wires with direct electric resistance heat treatment (DERHT) method in three-point bending tests. Two superelastic Ni-Ti wires (wire A: Smart SE, wire B: SENTALLOY SE, 0.406 mm × 0.559 mm) and 2 heat-actived Ni-Ti wires (wire C: Smart SM, wire D: L&H TITAN, 0.406 mm × 0.559 mm) were selected. They were heat-treated using the DERHT method by a controlled electric current (6.36 A) applied for different period of time [0 (control), 1.0, 1.5, 2.0, 2.5 seconds). Then, a three-point bending test was performed under controlled temperature (37°C) to examine the relationships between the deflection and the load in the bending of wires. After DERHT treatment, the plateau in the force-deflection curve of superelastic Ni-Ti wires and heat-activated Ni-Ti wires were increased. When the wires were heated for 2.0 seconds and deflected to 1.5 mm, the loading force of A, B, C and D Ni-Ti wires increased from (3.85 ± 0.11), (3.62 ± 0.07), (3.28 ± 0.09), (2.91 ± 0.23) N to (4.33 ± 0.07), (4.07 ± 0.05), (4.52 ± 0.08), (3.27 ± 0.15) N respectively. DERHT method is very convenient for clinical use. It is possible to change the arch form and superelastic force of NiTi wires. The longer the heating time is, the more the superelastic characteristics of the wires are altered.

Aircraft Electromagnetic Compatibility.

DTIC Science & Technology

1987-06-01

Human Exposure to Radio Frequency Electromagnetic Fields , 300 KiloHertz to 100 GigaHertz." 6. ARINC 429-8, "Digital Information Transfer System (DITS...142 V EXECUTIVE SUMMARY The Aircraft Electromagnetic Compatibility guidelines document deals with electromagnetic compatibility in a... electromagnetic interference paths (figure EI. TYPE PATH 400 Hz Electrostatic MagneticCharge Electric Field Transients 5 R d t Coupling 150/i 300o Wire

Method of fabricating high-density hermetic electrical feedthroughs using insulated wire bundles

DOEpatents

Shah, Kedar G.; Benett, William J.; Pannu, Satinderpall S.

2016-05-10

A method of fabricating electrical feedthroughs coats of a plurality of electrically conductive wires with an electrically insulating material and bundles the coated wires together in a substantially parallel arrangement. The bundled coated wires are secured to each other by joining the electrically insulating material of adjacent wires together to form a monolithic block which is then cut transverse to the wires to produce a block section having opposing first and second sides with a plurality of electrically conductive feedthroughs extending between them.

Nanowire electron scattering spectroscopy

NASA Technical Reports Server (NTRS)

Hunt, Brian D. (Inventor); Bronikowski, Michael (Inventor); Wong, Eric W. (Inventor); von Allmen, Paul (Inventor); Oyafuso, Fabiano A. (Inventor)

2009-01-01

Methods and devices for spectroscopic identification of molecules using nanoscale wires are disclosed. According to one of the methods, nanoscale wires are provided, electrons are injected into the nanoscale wire; and inelastic electron scattering is measured via excitation of low-lying vibrational energy levels of molecules bound to the nanoscale wire.

Thin-film chip-to-substrate interconnect and methods for making same

DOEpatents

Tuckerman, D.B.

1988-06-06

Integrated circuit chips are electrically connected to a silicon wafer interconnection substrate. Thin film wiring is fabricated down bevelled edges of the chips. A subtractive wire fabrication method uses a series of masks and etching steps to form wires in a metal layer. An additive method direct laser writes or deposits very thin lines which can then be plated up to form wires. A quasi-additive or subtractive/additive method forms a pattern of trenches to expose a metal surface which can nucleate subsequent electrolytic deposition of wires. Low inductance interconnections on a 25 micron pitch (1600 wires on a 1 cm square chip) can be produced. The thin film hybrid interconnect eliminates solder joints or welds, and minimizes the levels of metallization. Advantages include good electrical properties, very high wiring density, excellent backside contact, compactness, and high thermal and mechanical reliability. 6 figs.

Thin-film chip-to-substrate interconnect and methods for making same

DOEpatents

Tuckerman, David B.

1991-01-01

Integrated circuit chips are electrically connected to a silica wafer interconnection substrate. Thin film wiring is fabricated down bevelled edges of the chips. A subtractive wire fabrication method uses a series of masks and etching steps to form wires in a metal layer. An additive method direct laser writes or deposits very thin metal lines which can then be plated up to form wires. A quasi-additive or subtractive/additive method forms a pattern of trenches to expose a metal surface which can nucleate subsequent electrolytic deposition of wires. Low inductance interconnections on a 25 micron pitch (1600 wires on a 1 cm square chip) can be produced. The thin film hybrid interconnect eliminates solder joints or welds, and minimizes the levels of metallization. Advantages include good electrical properties, very high wiring density, excellent backside contact, compactness, and high thermal and mechanical reliability.

Investigations of ultrafast charge dynamics in laser-irradiated targets by a self probing technique employing laser driven protons

NASA Astrophysics Data System (ADS)

Ahmed, H.; Kar, S.; Cantono, G.; Nersisyan, G.; Brauckmann, S.; Doria, D.; Gwynne, D.; Macchi, A.; Naughton, K.; Willi, O.; Lewis, C. L. S.; Borghesi, M.

2016-09-01

The divergent and broadband proton beams produced by the target normal sheath acceleration mechanism provide the unique opportunity to probe, in a point-projection imaging scheme, the dynamics of the transient electric and magnetic fields produced during laser-plasma interactions. Commonly such experimental setup entails two intense laser beams, where the interaction produced by one beam is probed with the protons produced by the second. We present here experimental studies of the ultra-fast charge dynamics along a wire connected to laser irradiated target carried out by employing a 'self' proton probing arrangement - i.e. by connecting the wire to the target generating the probe protons. The experimental data shows that an electromagnetic pulse carrying a significant amount of charge is launched along the wire, which travels as a unified pulse of 10s of ps duration with a velocity close to speed of light. The experimental capabilities and the analysis procedure of this specific type of proton probing technique are discussed.

Consideration of IP Telephony Quality on the IEEE802.11a Wireless LAN

NASA Astrophysics Data System (ADS)

Miyashita, Michifumi; Takamatsu, Hideyuki; Kurono, Masahiro

Recently, IP telephony services in wired network are started, and paid attention for its charge-free nature due to IP technology. On the other hand, the Hot-Spot service, which provides one to access the Internet at the public space such as cafe, using the IEEE wireless LAN has been evolved, and it is expected that the IP telephony service on the Hot-Spot network will be developed. However, the IP telephony quality on the IEEE802.11a wireless LAN has not been fully studied yet. In this paper, we discuss about the quality of IP telephony service on the IEEE802.11a wireless LAN from the aspect of R-value, and show ability to improve the IP telephony quality on the Hot-Spot network employing PLC function defined in the ITU-T Recommendation G.711 Appendix I.

Hot Corrosion Behavior of Arc-Sprayed Highly Dense NiCr-Based Coatings in Chloride Salt Deposit

NASA Astrophysics Data System (ADS)

Qin, Enwei; Yin, Song; Ji, Hua; Huang, Qian; Liu, Zekun; Wu, Shuhui

2017-04-01

To make cities more environmentally friendly, combustible wastes tend to be incinerated in waste-to-energy power plant boilers. However, release of chlorine gas (Cl2) during incineration causes serious problems related to hot corrosion of boiler tubes and poses a safety threat for such plants. In this study, a pseudo-de Laval nozzle was employed in a twin-wire arc spray system to enhance the velocity of in-flight particles. Highly dense NiCr-based coatings were obtained using the modified nozzle gun. The coating morphology was characterized by optical microscopy and scanning electron microscopy, and hot corrosion testing was carried out in a synthetic molten chloride salt environment. Results showed that the dense NiCr-based coatings exhibited high resistance against corrosion by chlorine, which can be related to the typical splat lamellar microstructure and chemical composition as well as minor alloying elements such as Ti and Mo.

Bibliography on aircraft fire hazards and safety. Volume 1: Hazards. Part 1: Key numbers 1 to 817

NASA Technical Reports Server (NTRS)

Pelouch, J. J., Jr. (Compiler); Hacker, P. T. (Compiler)

1974-01-01

Ignition temperatures of n-hexane, n-octane, n-decane, JP-6 jet fuel, and aircraft engine oil MIL-7-7808 (0-60-18) were determined in air using heated Pyrex cylinders and Nichrome wires, rods, or tubes. Ignition temperature varied little with fuel-air ratio, but increased as the size of the heat source was decreased. Expressions are given which define the variation of the hot surface ignition temperatures of these combustibles with the radius and the surface area of the heat source. The expressions are applicable to stagnant or low velocity flow conditions (less than 0.2 in./sec.). In addition, the hot gas ignition temperatures of the combustible vapor-air mixtures were determined with jets of hot air. These ignition temperatures also varied little with fuel-air ratio and increased as the diameter of the heat sources was decreased.

Slow hot carrier cooling in cesium lead iodide perovskites

NASA Astrophysics Data System (ADS)

Shen, Qing; Ripolles, Teresa S.; Even, Jacky; Ogomi, Yuhei; Nishinaka, Koji; Izuishi, Takuya; Nakazawa, Naoki; Zhang, Yaohong; Ding, Chao; Liu, Feng; Toyoda, Taro; Yoshino, Kenji; Minemoto, Takashi; Katayama, Kenji; Hayase, Shuzi

2017-10-01

Lead halide perovskites are attracting a great deal of interest for optoelectronic applications such as solar cells, LEDs, and lasers because of their unique properties. In solar cells, heat dissipation by hot carriers results in a major energy loss channel responsible for the Shockley-Queisser efficiency limit. Hot carrier solar cells offer the possibility to overcome this limit and achieve energy conversion efficiency as high as 66% by extracting hot carriers. Therefore, fundamental studies on hot carrier relaxation dynamics in lead halide perovskites are important. Here, we elucidated the hot carrier cooling dynamics in all-inorganic cesium lead iodide (CsPbI3) perovskite using transient absorption spectroscopy. We observe that the hot carrier cooling rate in CsPbI3 decreases as the fluence of the pump light increases and the cooling is as slow as a few 10 ps when the photoexcited carrier density is 7 × 1018 cm-3, which is attributed to phonon bottleneck for high photoexcited carrier densities. Our findings suggest that CsPbI3 has a potential for hot carrier solar cell applications.

Thin film temperature sensor

NASA Technical Reports Server (NTRS)

Grant, H. P.; Przybyszewski, J. S.

1980-01-01

Thin film surface temperature sensors were developed. The sensors were made of platinum-platinum/10 percent rhodium thermocouples with associated thin film-to-lead wire connections and sputtered on aluminum oxide coated simulated turbine blades for testing. Tests included exposure to vibration, low velocity hydrocarbon hot gas flow to 1250 K, and furnace calibrations. Thermal electromotive force was typically two percent below standard type S thermocouples. Mean time to failure was 42 hours at a hot gas flow temperature of 1250 K and an average of 15 cycles to room temperature. Failures were mainly due to separation of the platinum thin film from the aluminum oxide surface. Several techniques to improve the adhesion of the platinum are discussed.

Apparatus for monitoring two-phase flow

DOEpatents

Sheppard, John D.; Tong, Long S.

1977-03-01

A method and apparatus for monitoring two-phase flow is provided that is particularly related to the monitoring of transient two-phase (liquid-vapor) flow rates such as may occur during a pressurized water reactor core blow-down. The present invention essentially comprises the use of flanged wire screens or similar devices, such as perforated plates, to produce certain desirable effects in the flow regime for monitoring purposes. One desirable effect is a measurable and reproducible pressure drop across the screen. The pressure drop can be characterized for various known flow rates and then used to monitor nonhomogeneous flow regimes. Another useful effect of the use of screens or plates in nonhomogeneous flow is that such apparatus tends to create a uniformly dispersed flow regime in the immediate downstream vicinity. This is a desirable effect because it usually increases the accuracy of flow rate measurements determined by conventional methods.

Cars Spectroscopy of Propellant Flames

DTIC Science & Technology

1983-11-01

applicability of CARS in studies of the combustion of propellants and other reactive systems. Broadband CARS spectra were obtained from both the reaction zone...ref 12). When ienited vith a flame, propellant burned in air with a luainous flame. A-e Ignittou with i hot wire resulted in flameless burning (fizz...ester). Current models of nitramine propellant combustion are essentially models of HMX (cyclotetranithylene tetranitramine) and RDX deflagration. The

A cooperative program to stimulate student involvement through the MIT Undergraduate Research Opportunity Program

NASA Technical Reports Server (NTRS)

1984-01-01

Flow characteristics in the low speed Wright Brothers Wind Tunnel were studied. Calculations to check the precision of the tunnel were conducted. A program for generating computational grids around an airfoil was developed and compared with the wind tunnel model. Low Reynolds number flow phenomenon of periodic vortex shedding in a wake were also studied by applying a hot-wire anomemeter.

Wire EDM for Refractory Materials

NASA Technical Reports Server (NTRS)

Zellars, G. R.; Harris, F. E.; Lowell, C. E.; Pollman, W. M.; Rys, V. J.; Wills, R. J.

1982-01-01

In an attempt to reduce fabrication time and costs, Wire Electrical Discharge Machine (Wire EDM) method was investigated as tool for fabricating matched blade roots and disk slots. Eight high-strength nickel-base superalloys were used. Computer-controlled Wire EDM technique provided high quality surfaces with excellent dimensional tolerances. Wire EDM method offers potential for substantial reductions in fabrication costs for "hard to machine" alloys and electrically conductive materials in specific high-precision applications.

Protecting western redcedar from deer browsing—with a passing reference to TRP channels

PubMed Central

Romanovsky, Andrej A

2015-01-01

This editorial is about tree farming. It proposes to test in an experiment whether co-planting (in the same hole) western redcedar (WRC, Thuja plicata) with Sitka spruce (Picea sitchensis) protects WRC seedlings from wildlife browsing. This sustainable protection method is an alternative to the traditional use of mechanical devices and big-game repellents. Many repellents contain transient receptor potential (TRP) agonists, such as capsaicin, a TRP vanilloid-1 agonist. This editorial also delivers a puzzle: while herbivores avoid capsaicin, why do people living in hot climates consume large quantities of it (in chili peppers)? PMID:27227013

A Novel Method of Coating Orthodontic Archwires with Nanoparticles

PubMed Central

Syed, Shibli S; Kulkarni, Dinraj; Todkar, Rohit; Bagul, Ravikiran S; Parekh, Kreena; Bhujbal, Nikita

2015-01-01

Background: The major hazard to the orthodontic tooth movement is the friction developing at the bracket wire interface. In the past, there have been various attempts to reduce this friction. We believe that coating the commercially available orthodontic wires with nanoparticles can result in a successful reduction of this friction. The objective of this study is to develop a novel method of coating orthodontic archwires with nanoparticles. Materials and Methods: Stainless steel (Ormco, CA, USA), titanium molybdenum alloy (Ormco, CA, USA) and nickel-titanium (G and H Wire Company, USA) orthodontic wires with a rectangular cross-section dimension of 0.019”× 0.025”, were selected. The wires were later coated with a uniform and smooth nanoparticle film using 100 ml nanocremics. The coating procedure described in this article is a sol-gel thin film dip coating method. Results: The coating procedure was verified by comparing the surface topography of nanocoated archwires with the commercially available archwires in an environmental scanning electron microscope (ESEM). The ESEM images prove that the surface topography of the coated wires was found to be smoother with less surface deteriorations as compared to the commercially available wires. Conclusion: Commercially available orthodontic wires can be successfully coated using a novel method of sol-gel thin film dip coating method. PMID:26028899

Transient liquid-crystal technique used to produce high-resolution convective heat-transfer-coefficient maps

NASA Technical Reports Server (NTRS)

Hippensteele, Steven A.; Poinsatte, Philip E.

1993-01-01

In this transient technique the preheated isothermal model wall simulates the classic one-dimensional, semi-infinite wall heat transfer conduction problem. By knowing the temperature of the air flowing through the model, the initial temperature of the model wall, and the surface cooling rate measured at any location with time (using the fast-response liquid-crystal patterns recorded on video tape), the heat transfer coefficient can be calculated for the color isothermal pattern produced. Although the test was run transiently, the heat transfer coefficients are for the steady-state case. The upstream thermal boundary condition was considered to be isothermal. This transient liquid-crystal heat-transfer technique was used in a transient air tunnel in which a square-inlet, 3-to-1 exit transition duct was placed. The duct was preheated prior to allowing room temperature air to be suddenly drawn through it. The resulting isothermal contours on the duct surfaces were revealed using a surface coating of thermochromic liquid crystals that display distinctive colors at particular temperatures. A video record was made of the temperature and time data for all points on the duct surfaces during each test. The duct surfaces were uniformly heated using two heating systems: the first was an automatic temperature-controlled heater blanket completely surrounding the test duct like an oven, and the second was an internal hot-air loop through the inside of the test duct. The hot-air loop path was confined inside the test duct by insulated heat dams located at the inlet and exit ends of the test duct. A recirculating fan moved hot air into the duct inlet, through the duct, out of the duct exit, through the oven, and back to the duct inlet. The temperature nonuniformity of the test duct model wall was held very small. Test results are reported for two inlet Reynolds numbers of 200,000 and 1,150,000 (based on the square-inlet hydraulic diameter) and two free-stream turbulence intensities of about 1 percent, which is typical of wind tunnels, and up to 20 percent (using a grid), which is typical of real engine conditions.

Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Zhi; Wan, Yan; Yang, Mengjin

The Shockley-Queisser limit for solar cell efficiency can be overcome if hot carriers can be harvested before they thermalize. Recently, carrier cooling time up to 100 picoseconds was observed in hybrid perovskites, but it is unclear whether these long-lived hot carriers can migrate long distance for efficient collection. Here, we report direct visualization of hot-carrier migration in methylammonium lead iodide (CH 3NH 3PbI 3) thin films by ultrafast transient absorption microscopy, demonstrating three distinct transport regimes. Quasiballistic transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers transport distance that could overcome grain boundaries. Themore » nonequilibrium transport persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport limit. Lastly, these results suggest potential applications of hot-carrier devices based on hybrid perovskites.« less

Long-range hot-carrier transport in hybrid perovskites visualized by ultrafast microscopy

DOE PAGES

Guo, Zhi; Wan, Yan; Yang, Mengjin; ...

2017-04-07

The Shockley-Queisser limit for solar cell efficiency can be overcome if hot carriers can be harvested before they thermalize. Recently, carrier cooling time up to 100 picoseconds was observed in hybrid perovskites, but it is unclear whether these long-lived hot carriers can migrate long distance for efficient collection. Here, we report direct visualization of hot-carrier migration in methylammonium lead iodide (CH 3NH 3PbI 3) thin films by ultrafast transient absorption microscopy, demonstrating three distinct transport regimes. Quasiballistic transport was observed to correlate with excess kinetic energy, resulting in up to 230 nanometers transport distance that could overcome grain boundaries. Themore » nonequilibrium transport persisted over tens of picoseconds and ~600 nanometers before reaching the diffusive transport limit. Lastly, these results suggest potential applications of hot-carrier devices based on hybrid perovskites.« less

46 CFR 111.60-11 - Wire.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD... Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be component insulated. (c) Wire, other than in switchboards, must meet the requirements in sections 24.6.7 and...

46 CFR 111.60-11 - Wire.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Wire. 111.60-11 Section 111.60-11 Shipping COAST GUARD... Wiring Materials and Methods § 111.60-11 Wire. (a) Wire must be in an enclosure. (b) Wire must be component insulated. (c) Wire, other than in switchboards, must meet the requirements in sections 24.6.7 and...

Numerical investigation of airflow in an idealised human extra-thoracic airway: a comparison study

PubMed Central

Chen, Jie; Gutmark, Ephraim

2013-01-01

Large eddy simulation (LES) technique is employed to numerically investigate the airflow through an idealised human extra-thoracic airway under different breathing conditions, 10 l/min, 30 l/min, and 120 l/min. The computational results are compared with single and cross hot-wire measurements, and with time-averaged flow field computed by standard k-ω and k-ω-SST Reynolds averaged Navier-Stokes (RANS) models and the Lattice-Boltzmann method (LBM). The LES results are also compared to root-mean-square (RMS) flow field computed by the Reynolds stress model (RSM) and LBM. LES generally gives better prediction of the time-averaged flow field than RANS models and LBM. LES also provides better estimation of the RMS flow field than both the RSM and the LBM. PMID:23619907