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1

Joule heat in point contacts  

Microsoft Academic Search

We considered Joule heat in point contacts which are the elementary building blocks of ballistic devices with nonlocal transport based on two dimensional electron gas. We present a theory of a point contact up to second order in the applied voltage. Out of our calculation arises the main difference in Joule heat delivery between local and nonlocal transport. While for

Michal Rokni; Y. Levinson

1995-01-01

2

Estimating Joule Heating using Different Methods  

Microsoft Academic Search

Joule Heating is the Ohmic heat dissipation in the upper atmosphere due to the collision of neutrals and drifting charged particles. Joule Heating constitutes one of the most dominant energy sinks of the upper atmosphere from the magnetosphere during substorms and geomagnetic storms. Joule Heating can be estimated by several ways including the use of proxies like AE index, or

Emine Ceren Kalafatoglu; Zerefsan Kaymaz; J. Michael Ruohoniemi

2010-01-01

3

Joule heating at high latitudes  

Microsoft Academic Search

High latitude Joule heating has been calculated from simultaneous observations of the electric field magnitude and the Pedersen conductivity calculated from individual measurements of the ion drift velocity and particle precipitation observed over the lifetime of the AE-C satellite. The data were sorted by latitude, local time, hemisphere, season, and Kp index and separate averages of the electric field magnitude,

J. C. Foster; J.-P. St.-Maurice; V. J. Abreu

1983-01-01

4

Enhanced Joule Heating in Umbral Dots  

E-print Network

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

Joshi, Chandrashekhar; Jaaffrey, S N A

2007-01-01

5

Enhanced Joule Heating in Umbral Dots  

E-print Network

We present a study of magnetic profiles of umbral dots (UDs) and its consequences on the Joule heating mechanisms. Hamedivafa (2003) studied Joule heating using vertical component of magnetic field. In this paper UDs magnetic profile has been investigated including the new azimuthal component of magnetic field which might explain the relatively larger enhancement of Joule heating causing more brightness near circumference of UD.

Chandan Joshi; Lokesh Bharti; S. N. A. Jaaffrey

2007-05-08

6

Joule-Thomson expander and heat exchanger  

NASA Technical Reports Server (NTRS)

The Joule-Thomson Expander and Heat Exchanger Program was initiated to develop an assembly (JTX) which consists of an inlet filter, counterflow heat exchanger, Joule-Thomson expansion device, and a low pressure jacket. The program objective was to develop a JTX which, when coupled to an open cycle supercritical helium refrigerating system (storage vessel), would supply superfluid helium (He II) at 2 K or less for cooling infrared detectors.

Norman, R. H.

1976-01-01

7

Electroosmotic flow with Joule heating effects  

Microsoft Academic Search

Electroosmotic flow with Joule heating effects was examined numerically and experimentally in this work. We used a fluorescence-based thermometry technique to measure the liquid temperature variation caused by Joule heating along a micro capillary. We used a caged-fluorescent dye-based microfluidic visualization technique to measure the electroosmotic velocity profile along the capillary. Sharp temperature drops close to the two ends and

Xiangchun Xuan; Bo Xu; David Sintonb; Dongqing Li

2004-01-01

8

High-latitude Joule heating response to IMF inputs  

Microsoft Academic Search

We evaluate the response of the high-latitude Joule heating to orientation and magnitude of the interplanetary magnetic field (IMF). Approximately 9000 individual Joule heating patterns derived from data assimilation for the northern hemisphere were used to develop averaged and hemispherically integrated Joule power maps for the northern hemisphere north of 40° magnetic latitude. Hemispherically integrated Joule heating increases with IMF

M. McHarg; F. Chun; D. Knipp; G. Lu; B. Emery; A. Ridley

2005-01-01

9

Hemispherical Joule heating and the AE indices  

Microsoft Academic Search

A linear regression analysis is conducted for Joule energy deposition rates that have been integrated over the Northern Hemisphere as a function of the standard auroral electrojet indices. A correlation coefficient of 0.7-0.9 is obtained. The hemispherical Joule heating rate can be calculated through the substitution of 1 nT in the AE index by approximately 0.3 GW. A higher scale

W. Baumjohann; Y. Kamide

1984-01-01

10

Analysis of Joule heating in multilevel interconnects  

Microsoft Academic Search

Metal Joule heating in interconnects is studied numerically. Representative models featuring multilevel interconnect structures (from single level to eight level) are used for the finite element analysis. Particular attention is devoted to the effects of current density, the number of conductor levels, and the materials used as the metallization and interlevel dielectrics. Transient heat conduction analyses are carried out to

Y.-L. Shen

1999-01-01

11

Joule heating in high magnetic field pulsars  

E-print Network

We study the efficiency of Joule heating in the crustal layers of young neutron stars. It is shown that dissipation of the magnetic field is highly inhomogeneous in the crust with much faster dissipation in relatively low density layers. In young neutron stars, the rate of Joule heating in the crust can exceed the standard luminosity of non-magnetic star and can even be comparable to the luminosity of magnetars. The results of calculations are compared with the available observational data. We argue that the crustal field model can well account for the data on the surface temperature and magnetic field of young neutron stars.

Urpin, V

2008-01-01

12

Joule heating in high magnetic field pulsars  

E-print Network

We study the efficiency of Joule heating in the crustal layers of young neutron stars. It is shown that dissipation of the magnetic field is highly inhomogeneous in the crust with much faster dissipation in relatively low density layers. In young neutron stars, the rate of Joule heating in the crust can exceed the standard luminosity of non-magnetic star and can even be comparable to the luminosity of magnetars. The results of calculations are compared with the available observational data. We argue that the crustal field model can well account for the data on the surface temperature and magnetic field of young neutron stars.

V. Urpin; D. Konenkov

2008-04-01

13

Remote Joule heating by a carbon nanotube  

NASA Astrophysics Data System (ADS)

Minimizing Joule heating remains an important goal in the design of electronic devices. The prevailing model of Joule heating relies on a simple semiclassical picture in which electrons collide with the atoms of a conductor, generating heat locally and only in regions of non-zero current density, and this model has been supported by most experiments. Recently, however, it has been predicted that electric currents in graphene and carbon nanotubes can couple to the vibrational modes of a neighbouring material, heating it remotely. Here, we use in situ electron thermal microscopy to detect the remote Joule heating of a silicon nitride substrate by a single multiwalled carbon nanotube. At least 84% of the electrical power supplied to the nanotube is dissipated directly into the substrate, rather than in the nanotube itself. Although it has different physical origins, this phenomenon is reminiscent of induction heating or microwave dielectric heating. Such an ability to dissipate waste energy remotely could lead to improved thermal management in electronic devices.

Baloch, Kamal H.; Voskanian, Norvik; Bronsgeest, Merijntje; Cumings, John

2012-05-01

14

Research Article Joule heating effects on electroosmotic flow  

E-print Network

Research Article Joule heating effects on electroosmotic flow in insulator-based dielectrophoresis field around the in-channel insulator, Joule heating often becomes an unavoidable issue that may disturb as a result of the action of the electric field on Joule heating- induced fluid inhomogeneities

Xuan, Xiangchun "Schwann"

15

Joule heating during solid tissue electroporation  

Microsoft Academic Search

The application of high-voltage pulses to biological tissue causes not only electroporation, a non-thermal phenomenon of pore\\u000a creation within a lipid membrane due to an elevated electric field, but also significant heating. Once a biological membrane\\u000a is porated, the current density increases several times, causing Joule heating. A combined experimental and theoretical study\\u000a is reported. The theoretical temperature rise for

U. Pliquett

2003-01-01

16

Joule heating in the high-latitude mesosphere  

Microsoft Academic Search

The contribution made by Joule dissipation to heating of the daytime high-latitude upper mesosphere is discussed. During solar proton precipitation events in regions of large electric fields, Joule dissipation can be substantially larger than the local solar heating rate. Altitude profiles of Joule dissipation are presented for the polar cleft region for the August 4, 1972, solar proton event.

Peter M. Banks

1979-01-01

17

Optimal joule heating of the subsurface  

DOEpatents

A method for simultaneously heating the subsurface and imaging the effects of the heating is disclosed. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Berryman, J.G.; Daily, W.D.

1994-07-05

18

Optimal joule heating of the subsurface  

SciTech Connect

A method for simultaneously heating the subsurface and imaging the effects of the heating. This method combines the use of tomographic imaging (electrical resistance tomography or ERT) to image electrical resistivity distribution underground, with joule heating by electrical currents injected in the ground. A potential distribution is established on a series of buried electrodes resulting in energy deposition underground which is a function of the resistivity and injection current density. Measurement of the voltages and currents also permits a tomographic reconstruction of the resistivity distribution. Using this tomographic information, the current injection pattern on the driving electrodes can be adjusted to change the current density distribution and thus optimize the heating. As the heating changes conditions, the applied current pattern can be repeatedly adjusted (based on updated resistivity tomographs) to affect real time control of the heating.

Berryman, James G. (Danville, CA); Daily, William D. (Livermore, CA)

1994-01-01

19

Lateral crystallization of silicon films using Joule heating  

Microsoft Academic Search

We report lateral crystalline grain growth of silicon thin films by a combination of the crystallization by the electrical current induced Joule heating method with rapid substrate heating. A Cr strip was heated by electrical current induced joule heating. Due to heat diffusion from the Cr heater, a temperature gradient was formed in the lateral direction of the silicon films.

Nobuyuki Andoh; Toshiyuki Sameshima

2003-01-01

20

An Analytical Model of Joule Heating in Piezoresistive Microcantilevers  

PubMed Central

The present study investigates Joule heating in piezoresistive microcantilever sensors. Joule heating and thermal deflections are a major source of noise in such sensors. This work uses analytical and numerical techniques to characterise the Joule heating in 4-layer piezoresistive microcantilevers made of silicon and silicon dioxide substrates but with the same U-shaped silicon piezoresistor. A theoretical model for predicting the temperature generated due to Joule heating is developed. The commercial finite element software ANSYS Multiphysics was used to study the effect of electrical potential on temperature and deflection produced in the cantilevers. The effect of piezoresistor width on Joule heating is also studied. Results show that Joule heating strongly depends on the applied potential and width of piezoresistor and that a silicon substrate cantilever has better thermal characteristics than a silicon dioxide cantilever. PMID:22163433

Ansari, Mohd Zahid; Cho, Chongdu

2010-01-01

21

WEIMER ELECTRIC POTENTIAL, CUR-RENT, AND JOULE HEATING MODELS  

E-print Network

WEIMER ELECTRIC POTENTIAL, CUR- RENT, AND JOULE HEATING MODELS 1. Model content The Weimer into the ionosphere, which is dissipated in the iono- sphere as Joule heating. The models require solar wind flux/heating are mapped to an altitude of 110 km. In- put locations are specified as latitude

Michigan, University of

22

Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems  

E-print Network

Joule heating and heat transfer in poly(dimethylsiloxane) microfluidic systems David Erickson (using a 3D "whole-chip" finite element model) approach is used to examine Joule heating and heat is the internal heat generation (commonly referred to as Joule heating) caused by current flow through the buffer

Erickson, David

23

Stability of graphene nanoribbon edges under high temperature joule heating  

Microsoft Academic Search

Graphene nanoribbon edges have generated a lot of research interests recently, due to the different electronic properties of the ribbons arising from zigzag and armchair edges. Recent progress has shown that atomically smooth graphene nanoribbon edges can be produced using joule heating. In order to fully understand the joule heating process and study the stability of graphene nanoribbon edges, we

Xiaoting Jia; Mario Hofmann; Vincent Meunier; Bobby Sumpter; Jessica Campos-Delgado; Jose Romo-Herrera; Jing Kong; Mauricio Terrones; Mildred Dresselhaus

2010-01-01

24

Detection of Joule heating before dielectric breakdown in polyethylene films  

Microsoft Academic Search

Local Joule heating in polyethylene films was detected at room temperature before dielectric breakdown under DC field. When a high-temperature point appeared in a film, the conduction current increased with time. The final breakdown occurred at the point of the highest temperature. This concurrence of the breakdown point and the Joule heating point suggests that a thermal process takes part

Masayuki Nagao; Takashi Kimura; Y. Mizuno; M. Kosaki; M. Ieda

1990-01-01

25

Joule heating effects on peak broadening in capillary zone electrophoresis  

Microsoft Academic Search

Based on Taylor-Aris dispersion theory, a general analytical formula was derived for the theoretical plate height in capillary zone electrophoresis with the consideration of Joule heating effects. During the electrophoresis, the Joule heating causes a temperature rise and temperature gradients in the buffer solution. The temperature variations can affect the molecular diffusion, electroosmotic flow and electrophoretic flow via the temperature-dependent

Xiangchun Xuan; Dongqing Li

2004-01-01

26

Analytical and Numerical Study of Joule Heating Effects on Electrokinetically Pumped Continuous Flow PCR Chips  

E-print Network

Analytical and Numerical Study of Joule Heating Effects on Electrokinetically Pumped Continuous Form: December 8, 2007 Joule heating is an inevitable phenomenon for microfluidic chips involving been established and solved using the Green's function for evaluating Joule heating effects

Le Roy, Robert J.

27

Journal of Chromatography A, 1064 (2005) 227237 Analytical study of Joule heating effects on electrokinetic  

E-print Network

Journal of Chromatography A, 1064 (2005) 227­237 Analytical study of Joule heating effects Joule heating when electric currents are passing through electrolyte solutions. Joule heating not only an analytical model to study Joule heating effects on the transport of heat, electricity, momentum and mass

Xuan, Xiangchun "Schwann"

28

Stability of graphene nanoribbon edges under high temperature joule heating  

NASA Astrophysics Data System (ADS)

Graphene nanoribbon edges have generated a lot of research interests recently, due to the different electronic properties of the ribbons arising from zigzag and armchair edges. Recent progress has shown that atomically smooth graphene nanoribbon edges can be produced using joule heating. In order to fully understand the joule heating process and study the stability of graphene nanoribbon edges, we investigated the temperature that is reached during the joule heating process using metal particles. Metal particles on a suspended ribbon melt and evaporate with enough resistive joule heating, thereby providing a temperature calibrator of the ribbon surface. The successive melting process also provides a temperature gradient along the ribbon length. Thermodynamic calculations are carried out to estimate the melting point of the nanoparticles as a function of decreasing size. We also investigated the different edge junctions that were formed after the joule heating process. Our results showed that certain types of zigzag-armchair edge junctions are more dominant. Another type of zigzag-armchair edge junction, which is unstable, was found to reconstruct to form a stable edge junction during joule heating.

Jia, Xiaoting; Hofmann, Mario; Meunier, Vincent; Sumpter, Bobby; Campos-Delgado, Jessica; Romo-Herrera, Jose; Kong, Jing; Terrones, Mauricio; Dresselhaus, Mildred

2010-03-01

29

The Joule Heating of a Stable Pinched Plasma  

Microsoft Academic Search

The hydromagnetic equations are employed to obtain the conditions necessary for a pressure balance in a pinched discharge in ionized deuterium. The time dependent energy equation is integrated to give the time taken to heat the plasma by Joule heating with bremsstrahlung radiation losses only, and with a pressure balance maintained at all time. This heating time is shown to

M G Haines

1960-01-01

30

Global and local Joule heating effects seen by DE 2  

NASA Technical Reports Server (NTRS)

In the altitude region between 350 and 550 km, variations in the ion temperature principally reflect similar variations in the local frictional heating produced by a velocity difference between the ions and the neutrals. Here, the distribution of the ion temperature in this altitude region is shown, and its attributes in relation to previous work on local Joule heating rates are discussed. In addition to the ion temperature, instrumentation on the DE 2 satellite also provides a measure of the ion velocity vector representative of the total electric field. From this information, the local Joule heating rate is derived. From an estimate of the height-integrated Pedersen conductivity it is also possible to estimate the global (height-integrated) Joule heating rate. Here, the differences and relationships between these various parameters are described.

Heelis, R. A.; Coley, W. R.

1988-01-01

31

Inhomogeneous nanocrystallization of Joule-heated amorphous Vitroperm alloy  

Microsoft Academic Search

Crystallization of Vitroperm® alloy has been realized by means of Joule heating. The influence of the gas flow around the sample during the heat treatment is dramatic and it produces an inhomogeneous crystallization. For large enough gas flow the temperature of the sample surroundings can be considered constant and a temperature gradient appears over the sample width, which means a

V de Manuel; R P del Real

2008-01-01

32

Joule Heating of Alumina Barrier Layer during Anodization of Aluminum  

NASA Astrophysics Data System (ADS)

Simulation of heat distribution inside a porous alumina layer being formed by electrochemical anodization of aluminum has shown that Joule heating of the pore bottom is about four orders of magnitude more intense than that near the aluminum/oxide interface. As a result, microplasma formation is expected in this region.

Katsuba, P.; Yakimchuk, A.; Leshok, A.

2013-05-01

33

Acceleration of runaway electrons and Joule heating in solar flares  

Microsoft Academic Search

The electric-field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating time scales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic-field strength observed in flaring regions,

G. D. Holman

1985-01-01

34

Joule Heating of the Jovian Ionosphere by Corotation Enforcement Currents  

Microsoft Academic Search

A simple magnetodisk model is used to estimate the Joule heating rate, for several causes of departure from the corotation during whose enforcement heat is deposited on the Jovian magnetosphere. Following compression or expansion of the magnetosphere, the magnetospheric plasma sub- or super-rotates due to conservation of angular momentum and thermal energy is deposited in the ionosphere at a rate

Atsuhiro Nishida; Yukio Watanabe

1981-01-01

35

Joule heating effects on peak broadening in capillary zone electrophoresis  

NASA Astrophysics Data System (ADS)

Based on Taylor-Aris dispersion theory, a general analytical formula was derived for the theoretical plate height in capillary zone electrophoresis with the consideration of Joule heating effects. During the electrophoresis, the Joule heating causes a temperature rise and temperature gradients in the buffer solution. The temperature variations can affect the molecular diffusion, electroosmotic flow and electrophoretic flow via the temperature-dependent diffusion coefficient, dynamic viscosity and electrical conductivity. All these factors contribute to the peak broadening and are considered simultaneously in the present general model. The general formula derived in this paper is employed to discuss quantitatively the peak broadening in the presence of Joule heating effects. This formula can be easily extended to capillary zone electrophoresis with higher zeta potentials, if an approximate solution to Poisson-Boltzmann equation is employed.

Xuan, Xiangchun; Li, Dongqing

2004-08-01

36

Negative Joule Heating in Ion-Exchange Membranes  

E-print Network

In ion-exchange membrane processes, ions and water flow under the influence of gradients in hydrostatic pressure, ion chemical potential, and electrical potential (voltage), leading to solvent flow, ionic fluxes and ionic current. At the outer surfaces of the membranes, electrical double layers (EDLs) are formed (Donnan layers). When a current flows through the membrane, we argue that besides the positive Joule heating in the bulk of the membrane and in the electrolyte outside the membrane, there is also negative Joule heating in one of the EDLs. We define Joule heating as the inner product of the two vectors current and field strength. Also when fluid flows through a charged membrane, at one side of the membrane there is pressure-related cooling, due to the osmotic and hydrostatic pressure differences across the EDLs.

P. M. Biesheuvel; D. Brogioli; H. V. M. Hamelers

2014-02-06

37

Joule Heating in Neutron Stars under Strong Gravitation  

E-print Network

Considering Joule heating caused by the dissipation of the magnetic field in the neutron star crust to be an efficient mechanism in maintaining a relatively high surface temperature in very old neutron stars, the role of general relativity is investigated. It is found that, although the effect of space-time curvature produced by the intense gravitational field of the star slows down the decay rate of the magnetic field, modification of the initial magnetic field configuration and the initial field strength by the space-time curvature results in increasing the rate of Joule heating. Hence the space-time curvature supports Joule heating in maintaining a relatively high surface temperature which is consistent with the bservational detection.

Sujan Sengupta

2000-06-23

38

Negative Joule Heating in Ion-Exchange Membranes  

E-print Network

In ion-exchange membrane processes, ions and water flow under the influence of gradients in hydrostatic pressure, ion chemical potential, and electrical potential (voltage), leading to solvent flow, ionic fluxes and ionic current. At the outer surfaces of the membranes, electrical double layers (EDLs) are formed (Donnan layers). When a current flows through the membrane, we argue that besides the positive Joule heating in the bulk of the membrane and in the electrolyte outside the membrane, there is also negative Joule heating in one of the EDLs. We define Joule heating as the inner product of the two vectors current and field strength. Also when fluid flows through a charged membrane, at one side of the membrane there is pressure-related cooling, due to the osmotic and hydrostatic pressure differences across the EDLs.

Biesheuvel, P M; Hamelers, H V M

2014-01-01

39

Nonlinear phenomena in multiferroic nanocapacitor: Joule heating and electromechanical effects  

SciTech Connect

We demonstrate an approach for probing nonlinear electromechanical responses in BiFeO3 thin film nanocapacitors using half-harmonic band excitation piezoresponse force microscopy (PFM). Nonlinear PFM images of nanocapacitor arrays show clearly visible clusters of capacitors associated with variations of local leakage current through the BiFeO3 film. Strain spectroscopy measurements and finite element modeling point to significance of the Joule heating and show that the thermal effects caused by the Joule heating can provide nontrivial contributions to the nonlinear electromechanical responses in ferroic nanostructures. This approach can be further extended to unambiguous mapping of electrostatic signal contributions to PFM and related techniques.

Kim, Yunseok [ORNL; Kumar, Amit [ORNL; Tselev, Alexander [ORNL; Kravchenko, Ivan I [ORNL; Kalinin, Sergei V [ORNL; Jesse, Stephen [ORNL

2011-01-01

40

Joule Heating of the South Polar Terrain on Enceladus  

NASA Astrophysics Data System (ADS)

Accounting for the plumes and observed heat flux in the South Polar Terrain of Enceladus remains largely a mystery. We report that Joule heating in Enceladus may account for several, to a few tens of megawatts of power across the observed “tiger stripe” fractures. Electric currents passing through subsurface channels of low salinity and just a few kilometres in depth could supply a source of power to the South Polar Terrain, providing a small but previously unaccounted for contribution to the observed heat flux and plume activity. Examinations of electrical heating in the Jupiter system have led to conclusions that it is unimportant; however at Enceladus such heating may be an important contribution to localized heating and the persistence of the tiger stripes. The exclusion of salt ions during refreezing serves to enhance volumetric Joule heating and extend the lifetime of liquid water fractures in the South Polar Terrain.

Hand, K. P.; Khurana, K. K.; Chyba, C. F.

2009-12-01

41

Joule heating of the south polar terrain on Enceladus  

NASA Astrophysics Data System (ADS)

We report that Joule heating in Enceladus, resulting from the interaction of Enceladus with Saturn's magnetic field, may account for 150 kW to 52 MW of power through Enceladus. Electric currents passing through subsurface channels of low salinity and just a few kilometers in depth could supply a source of power to the south polar terrain, providing a small but previously unaccounted for contribution to the observed heat flux and plume activity. Studies of the electrical heating of Jupiter's moon Europa have concluded that electricity is a negligible heating source since no connection between the conductive subsurface and Alfvén currents has been observed. Here we show that, contrary to results for the Jupiter system, electrical heating may be a source of internal energy for Enceladus, contributing to localized heating, production of water vapor, and the persistence of the “tiger stripes.” This contribution is of order 0.001-0.25% of the total observed heat flux, and thus, Joule heating cannot explain the total south polar terrain heat anomaly. The exclusion of salt ions during refreezing serves to enhance volumetric Joule heating and could extend the lifetime of liquid water fractures in the south polar terrain.

Hand, K. P.; Khurana, K. K.; Chyba, C. F.

2011-04-01

42

Analysis and utilization of Joule heating in an electromagnet integrated microfluidic device for biological applications  

Microsoft Academic Search

Joule heating in the electromagnetic cell sorting system is problematic. Our micro-device was fabricated for the rapid separation by high magnetic field gradients of electromagnet and dissipates the Joule heat energy that causes unnecessary heat-up in the device. By using a cooling channel embedded in microfluidic channel, Joule heat can be reduced to dissipate thermal energy to an active area

Suk-Heung Song; Bong-Seop Kwak; Hyo-Il Jung

2009-01-01

43

Nanoscale Joule heating, Peltier cooling and current crowding at graphenemetal contacts  

E-print Network

Nanoscale Joule heating, Peltier cooling and current crowding at graphene�metal contacts Kyle L the presence of Joule heating9�11, current crowding12�16 and thermoelectric heating and cooling17 . Comparison and reducing the device lifetime18 . Joule heating in graphene transistors results in a local tempera- ture

King, William P.

44

Steady state Joule heating with temperature dependent conductivities  

Microsoft Academic Search

A general solution is given to the nonlinear steady state heat conduction equation for the case in which a metal is heated\\u000a by electrical conduction currents. The solution is valid for any temperature variation in the thermal and electrical conductivities\\u000a and is illustrated by application to a typical Joule heating situation in one dimension. Comparison of the case of temperature

John H. Young

1986-01-01

45

Postfabrication Electrical Trimming of Silicon Micromechanical Resonators via Joule Heating  

Microsoft Academic Search

This paper presents a method to electrically trim the resonance frequency of a silicon bulk acoustic resonator (SiBAR) after its fabrication is completed. The small volume of the mi- croresonator can be Joule heated to a sufficiently high temperature to allow for diffusion of deposited metals from its surface onto its bulk. Such high temperatures also facilitate the formation of

Ashwin K. Samarao; Farrokh Ayazi

2011-01-01

46

Crystallization of silicon films by rapid joule heating method  

Microsoft Academic Search

We report on the crystallization of silicon films by the joule heating method using Cr strip heater. We report on the lateral crystalline grain growth of silicon thin films by induced holes fabricated in Cr strip. A temperature gradient is generated by the holes, which causes lateral crystalline grain growth. The duration of the electrical current flow in the Cr

Nobuyuki Andoh; Toshiyuki Sameshima; Kuninori Kitahara

2005-01-01

47

Numerical calculation of electromigration under pulse current with Joule heating  

Microsoft Academic Search

Electromigration behavior under pulsed directional current (PDC) was investigated theoretically and experimentally. A vacancy diffusion equation under current stress was derived, and the relationship between vacancy concentration and time to failure was calculated numerically. The results show that if Joule heating is considered, the ratio of lifetime under PDC to that under DC is less than what was reported by

Zhihong Li; Guoying Wu; Yangyuan Wang; Zhiguo Li; Yinghua Sun

1999-01-01

48

Joule heating and temperature in the upper atmosphere  

Microsoft Academic Search

Joule heating has been shown to be very effective in increasing ; electronic temperature in the upper atmosphere. It is found theoretically that ; the electronic temperature can rise up to several thousands deg K soon after ; certain ionospheric current disturbances occur, while the temperature of neutral ; particles increases only very slowdy. Temperatures in various conditions have ;

S. Kato

1962-01-01

49

Global and local joule heating effects seen by DE 2  

Microsoft Academic Search

In the altitude region between 350 and 550 km, variations in the ion temperature principally reflect similar variations in the local frictional heating produced by a velocity difference between the ions and the neutrals. Here the authors show the distribution of the ion temperature in this altitude region and discuss its attributes in relation to previous work on local Joule

R.A. Heelis; W. R. Coley

1988-01-01

50

A model for Joule heating-induced dispersion in microchip electrophoresis  

E-print Network

A model for Joule heating-induced dispersion in microchip electrophoresis Yi Wang,a Qiao Lin-uniform temperature distributions in the channel resulting from Joule heating, and then determine variations by Joule heating effects in electrophoresis microchannels. In electrophoresis, an electric field is used

Lin, Qiao

51

Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels  

E-print Network

Joule heating effects on electrokinetic focusing and trapping of particles in constriction.1088/0960-1317/22/7/075011 Joule heating effects on electrokinetic focusing and trapping of particles in constriction microchannels.iop.org/JMM/22/075011 Abstract Joule heating (JH) is a ubiquitous phenomenon in electrokinetic microfluidic

Xuan, Xiangchun "Schwann"

52

Monte Carlo simulation of Joule heating in bulk and strained silicon and Robert W. Dutton  

E-print Network

Monte Carlo simulation of Joule heating in bulk and strained silicon Eric Popa and Robert W. Dutton; accepted 19 January 2005; published online 16 February 2005 This work examines the details of Joule heating and reliability of nanoscale and thin-film transistors. Joule heating is often simulated with the classical drift

Dutton, Robert W.

53

Effect of Joule heating on orientation of spheroidal particle in alternating electric field  

E-print Network

Effect of Joule heating on orientation of spheroidal particle in alternating electric field Yu electric conductivities. We show that the rate of Joule heating of the particle depends on the orientation of particle strongly varies with temperature, the Joule heating of the particle affects orientation dynamics

Elperin, Tov

54

Discretization of the Joule heating term for plasma discharge fluid models in unstructured meshes  

E-print Network

Discretization of the Joule heating term for plasma discharge fluid models in unstructured meshes T Keywords: Discharge modeling Plasma modeling Numerical method Joule heating Unstructured meshes a b s t r species is modeled by the Joule heating term which appears in the electron and heavy species (ion) energy

Raja, Laxminarayan L.

55

GENERATION OF HIGH FREQUENCY PHONONS PHONON GENERATION BY JOULE HEATING IN METAL FILMS  

E-print Network

GENERATION OF HIGH FREQUENCY PHONONS PHONON GENERATION BY JOULE HEATING IN METAL FILMS N. PERRIN metallic film, which provides a source of high energy phonons generated by Joule heating. The interface A thickness quency phonons is that of Joule heating [I]. The range, is evaporated onto a substrate

Boyer, Edmond

56

Joule heating and nitric oxide in the thermosphere, 2 Charles A. Barth1  

E-print Network

Joule heating and nitric oxide in the thermosphere, 2 Charles A. Barth1 Received 14 April 2010 and higher. These gravity waves are produced by Joule heating that occurs at latitudes of 60° and higher of increased nitric oxide produced by Joule heating initiated gravity waves and to determine how often downflow

Bailey, Scott

57

Joule heating and nitric oxide in the thermosphere C. A. Barth,1  

E-print Network

Joule heating and nitric oxide in the thermosphere C. A. Barth,1 G. Lu,2 and R. G. Roble2 Received] The effect of Joule heating on the density of nitric oxide in the thermosphere was studied using observations Ionosphere Electrodynamics General Circulation Model for a Joule heating event that occurred on 25 September

Bailey, Scott

58

A continuum-atomistic method for incorporating Joule heating into classical molecular dynamics simulations  

E-print Network

A continuum-atomistic method for incorporating Joule heating into classical molecular dynamics) A hybrid atomistic-continuum method is presented for incorporating Joule heating into large-scale molecular. The method is demonstrated by simulating Joule heating and melting, along with associated changes in current

Brenner, Donald W.

59

Loop formation in graphitic nanoribbon edges using furnace heating or Joule heating  

E-print Network

Here the authors report the use of either furnace heating or Joule heating to pacify the exposed graphene edges by loop formation in a novel graphitic nanoribbonmaterial, grown by chemical vapor deposition. The edge energy ...

Jia, Xiaoting

60

Investigation of Self-Heating Phenomenon in Small Geometry Vias Using Scanning Joule Expansion Microscopy  

E-print Network

Investigation of Self-Heating Phenomenon in Small Geometry Vias Using Scanning Joule Expansion conducting sample (W-Via) which produces sample Joule heating and temperature rise, resulting in sample ABSTRACT This paper reports the use of a novel thermometry technique, scanning Joule expansion microscopy

61

Joule heating generated by spin current through Josephson junctions  

SciTech Connect

We theoretically study the spin-polarized current flowing through a Josephson junction (JJ) in a spin injection device. When the spin-polarized current is injected from a ferromagnet in a superconductor (SC), the charge current is carried by the superconducting condensate (Cooper pairs), while the spin-up and spin-down currents flow in equal magnitude but in the opposite direction in a SC, because of no quasiparticle charge current in the SC. This indicates that not only the Josephson current but also the spin current flow across JJ at zero bias voltage, thereby generating Joule heating by the spin current. The result provides a new method for detecting the spin current by measuring Joule heating at JJ. {copyright} 2001 American Institute of Physics.

Takahashi, S.; Yamashita, T.; Koyama, T.; Maekawa, S.; Imamura, H.

2001-06-01

62

Joule heating and the thermal evolution of old neutron stars  

E-print Network

We consider Joule heating caused by dissipation of the magnetic field in the neutron star crust. This mechanism may be efficient in maintaining a relatively high surface temperature in very old neutron stars. Calculations of the thermal evolution show that, at the late evolutionary stage ($t \\geq 10$ Myr), the luminosity of the neutron star is approximately equal to the energy released due to the field dissipation and is practically independent of the atmosphere models. At this stage, the surface temperature can be of the order of $3 \\times 10^{4} - 10^{5}$K. Joule heating can maintain this high temperature during extremely long time ($\\geq 100$ Myr), comparable with the decay time of the magnetic field.

Juan A. Miralles; Vadim Urpin; Denis Konenkov

1998-03-06

63

F region ion temperature enhancements resulting from Joule heating  

Microsoft Academic Search

F region ion temperature measurements were made by the Chatanika and Millstone Hill incoherent scatter radars as part of the Magnetosphere-Ionosphere-Thermosphere Radar Studies program of coordinated high-latitude observations. At both radars, periods of enhanced ion temperature associated with Joule heating events were detected. A regular feature of the observations was the existence of larger and longer lasting temperature enhancements in

Murray J. Baron; Ronald H. Wand

1983-01-01

64

Joule heating induced by vortex motion in a type-II superconductor Z. L. Xiao and E. Y. Andrei  

E-print Network

Joule heating induced by vortex motion in a type-II superconductor Z. L. Xiao and E. Y. Andrei-II superconductor due to Joule heating induced by vortex motion. The effect of Joule heating is detected s duration, where the Joule heating is negligible and saturates, respectively. The thermometry is based

Andrei, Eva Y.

65

Joule Heating and Anomalous Resistivity in the Solar Corona  

E-print Network

Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as $2.5 \\times 10^9$ Amperes (Spangler 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of two dimensional magnetohydrodynamic turbulence. The Spitzer result for the resistivity is adopted as a lower limit to the true resistivity. The calculated volumetric heating rate is compared with an independent theoretical estimate by Cranmer et al (2007). This latter estimate accounts for the dynamic and thermodynamic properties of the corona at a heliocentric distance of several solar radii. Our calculated Joule heating rate is less than the Cranmer et al estimate by at least a factor of $3 \\times 10^5$. The currents inferred from the observations of Spangler (2007) are not relevant to coronal heating unless the true resistivity is enormously increased relative to the Spitzer value. However, the same model for turbulent current sheets used to calculate the heating rate also gives an electron drift speed which can be comparable to the electron thermal speed, and larger than the ion acoustic speed. It is therefore possible that the coronal current sheets are unstable to current-driven instabilities which produce high levels of waves, enhance the resistivity and thus the heating rate.

Steven R. Spangler

2008-12-22

66

Acceleration of runaway electrons and Joule heating in solar flares  

NASA Technical Reports Server (NTRS)

The electric field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating timescales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic field strength observed in flaring regions, place stringent restrictions upon the acceleration process. The role of the plasma resistivity in these processes is examined, and possible sources of anomalous resistivity are summarized. The implications of these results for the microwave and hard X-ray emission from solar flares are examined.

Holman, G. D.

1984-01-01

67

Acceleration of runaway electrons and Joule heating in solar flares  

NASA Technical Reports Server (NTRS)

The electric field acceleration of electrons out of a thermal plasma and the simultaneous Joule heating of the plasma are studied. Acceleration and heating timescales are derived and compared, and upper limits are obtained on the acceleration volume and the rate at which electrons can be accelerated. These upper limits, determined by the maximum magnetic field strength observed in flaring regions, place stringent restrictions upon the acceleration process. The role of the plasma resistivity in these processes is examined, and possible sources of anomalous resistivity are summarized. The implications of these results for the microwave and hard X-ray emission from solar flares are examined.

Holman, G. D.

1985-01-01

68

Joule heating of Io's ionosphere by unipolar induction currents  

NASA Technical Reports Server (NTRS)

Electrical induction in Io's ionosphere, due to the corotating plasma bound to the Jovian magnetosphere, is one possible source for the attainment of the high temperatures suggested by the large scale height of Io's ionosphere. Unipolar induction models are constructed to calculate ionospheric joule heating numerically, whose heating rates lie between 10 to the -9th and 10 to the -8th W/cu m. The binding and coupling of the ionosphere is due to the dense, and possibly ionized, neutral SO2 atmosphere, and there appears to be no need to postulate the existence of an intrinsic Ionian magnetic field in order to retain the observed ionnosphere.

Herbert, F.; Lichtenstein, B. R.

1980-01-01

69

Joule Heating and Anomalous Resistivity in the Solar Corona  

E-print Network

Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as $2.5 \\times 10^9$ Amperes (Spangler 2007). These estimates of currents are used to develop a model for Joule heating in the corona. It is assumed that the currents are concentrated in thin current sheets, as suggested by theories of two dimensional magnetohydrodynamic turbulence. The Spitzer result for the resistivity is adopted as a lower limit to the true resistivity. The calculated volumetric heating rate is compared with an independent theoretical estimate by Cranmer et al (2007). This latter estimate accounts for the dynamic and thermodynamic properties of the corona at a heliocentric distance of several solar radii. Our calculated Joule heating rate is less than the Cranmer et al estimate by at least a factor of $3 \\times 10^5$. The currents inferred from the observations of Spangler (2007) are not relevant to coronal heating unless the true resistivi...

Spangler, Steven R

2008-01-01

70

Joule heating governing the cooling of magnetized neutron stars  

E-print Network

We present two-dimensional simulations for the cooling of neutron stars with strong magnetic fields (B > 1e13 Gauss). We study how the cooling curves are influenced by magnetic field decay. We show that the Joule heating effects are very large and in some cases control the thermal evolution. We characterize the temperature anisotropy induced by the magnetic field and predict the surface temperature distribution for the early and late stages of the evolution of isolated neutron stars, comparing our results with available observational data of isolated neutron stars.

Aguilera, Deborah N; Miralles, Juan A

2008-01-01

71

Dispersion of the conductance of quantum nanowires and Joule heating  

NASA Astrophysics Data System (ADS)

The high-frequency ballistic conductance G(?) of a quantum wire connecting two classical reservoirs is discussed. It is supposed that the transverse size of the wire is on the order of the de Broglie wavelength of the conduction electrons. An expression for G(?) in a wide range of frequencies ? is given. The behavior of both active Re G(?) and reactive Im G(?) parts of the conductance is investigated. The frequency range is determined where the so-called kinetic inductance is dominant, i.e., Im G(?) is positive and larger than Re G(?). This range is defined by the condition that the time of flight of the conduction electrons along the wire length L exceeds the period of oscillation 2?/? of the electric potential. The Joule heat generation that accompanies the current flow through the quantum wire takes place in the reservoirs over a distance on the order of the mean free path of conduction electrons. The total rates of Joule heat generation are the same in both reservoirs.

Gurevich, V. L.

2013-01-01

72

Joule heating effects on reservoir-based dielectrophoresis.  

PubMed

Reservoir-based dielectrophoresis (rDEP) is a recently developed technique that exploits the inherent electric field gradients at a reservoir-microchannel junction to focus, trap, and sort particles. However, the locally amplified electric field at the junction is likely to induce significant Joule heating effects that are not considered in previous studies. This work investigates experimentally and numerically these effects on particle transport and control in rDEP processes in PDMS/PDMS microchips. It is found that Joule heating effects can reduce rDEP focusing considerably and may even disable rDEP trapping. This is caused by the fluid temperature rise at the reservoir-microchannel junction, which significantly increases the local particle velocity due to fluid flow and particle electrophoresis while has a weak impact on the particle velocity due to rDEP. The numerical predictions of particle stream width and electric current, which are the respective indicators of rDEP manipulation and fluid temperature, are demonstrated to both match the experimental measurements with a good accuracy. PMID:24165865

Kale, Akshay; Patel, Saurin; Qian, Shizhi; Hu, Guoqing; Xuan, Xiangchun

2014-03-01

73

A FINITE ELEMENT MODEL FOR THE TIME-DEPENDENT JOULE HEATING PROBLEM*  

E-print Network

A FINITE ELEMENT MODEL FOR THE TIME-DEPENDENT JOULE HEATING PROBLEM Subject Classification. 65N30, 65N15, 35K60. Key words and phrases. Joule heating, nonlinear, elliptic* *ial differential equation describing the electric heating of a conducting body. We prove err* *or

Larsson, Stig

74

Joule heating in the cooling of magnetized neutron stars  

E-print Network

We present 2D simulations of the cooling of neutron stars with strong magnetic fields (B \\geq 10^{13} G). We solve the diffusion equation in axial symmetry including the state of the art microphysics that controls the cooling such as slow/fast neutrino processes, superfluidity, as well as possible heating mechanisms. We study how the cooling curves depend on the the magnetic field strength and geometry. Special attention is given to discuss the influence of magnetic field decay. We show that Joule heating effects are very large and in some cases control the thermal evolution. We characterize the temperature anisotropy induced by the magnetic field for the early and late stages of the evolution of isolated neutron stars.

Deborah N. Aguilera; Jose A. Pons; Juan A. Miralles

2007-10-25

75

Joule heating in the cooling of magnetized neutron stars  

E-print Network

We present 2D simulations of the cooling of neutron stars with strong magnetic fields (B \\geq 10^{13} G). We solve the diffusion equation in axial symmetry including the state of the art microphysics that controls the cooling such as slow/fast neutrino processes, superfluidity, as well as possible heating mechanisms. We study how the cooling curves depend on the the magnetic field strength and geometry. Special attention is given to discuss the influence of magnetic field decay. We show that Joule heating effects are very large and in some cases control the thermal evolution. We characterize the temperature anisotropy induced by the magnetic field for the early and late stages of the evolution of isolated neutron stars.

Aguilera, Deborah N; Miralles, Juan A

2007-01-01

76

Electron kinetics and non-Joule heating in near-collisionless inductively coupled plasmas V. I. Kolobov  

E-print Network

Electron kinetics and non-Joule heating in near-collisionless inductively coupled plasmas V. I; colli- sional Joule heating predominates. Heating at low pres- sures is due to a combined effect of Joule heating and collisionless heating, there is an important regime of what we call ``hy

Economou, Demetre J.

77

Electro-osmotic infusion for joule heating soil remediation techniques  

DOEpatents

Electro-osmotic infusion of ground water or chemically tailored electrolyte is used to enhance, maintain, or recondition electrical conductivity for the joule heating remediation technique. Induced flows can be used to infuse electrolyte with enhanced ionic conductivity into the vicinity of the electrodes, maintain the local saturation of near-electrode regions and resaturate a partially dried out zone with groundwater. Electro-osmotic infusion can also tailor the conductivity throughout the target layer by infusing chemically modified and/or heated electrolyte to improve conductivity contrast of the interior. Periodic polarity reversals will prevent large pH changes at the electrodes. Electro-osmotic infusion can be used to condition the electrical conductivity of the soil, particularly low permeability soil, before and during the heating operation. Electro-osmotic infusion is carried out by locating one or more electrodes adjacent the heating electrodes and applying a dc potential between two or more electrodes. Depending on the polarities of the electrodes, the induced flow will be toward the heating electrodes or away from the heating electrodes. In addition, electrodes carrying a dc potential may be located throughout the target area to tailor the conductivity of the target area.

Carrigan, Charles R. (Tracy, CA); Nitao, John J. (Castro Valley, CA)

1999-01-01

78

Analytical study of Joule heating effects on electrokinetic transportation in capillary electrophoresis  

Microsoft Academic Search

Electric fields are often used to transport fluids (by electroosmosis) and separate charged samples (by electrophoresis) in microfluidic devices. However, there exists inevitable Joule heating when electric currents are passing through electrolyte solutions. Joule heating not only increases the fluid temperature, but also produces temperature gradients in cross-stream and axial directions. These temperature effects make fluid properties non-uniform, and hence

Xiangchun Xuan; Dongqing Li

2005-01-01

79

Electrokinetically controlled real-time polymerase chain reaction in microchannel using Joule heating effect  

Microsoft Academic Search

In this work, a new method to control polymerase chain reaction (PCR) thermal cycling in a microchannel using Joule heating effect was presented. Joule heating was generated internally by the current flow through the buffer solution in an electrokinetically-driven microfluidic chip without external heater component. Numerical simulations were developed and conducted to determine the parameters required to achieve the desired

Guoqing Hu; Qing Xiang; Rachel Fu; Bo Xu; Roberto Venditti; Dongqing Li

2006-01-01

80

Impact of Joule heating on scaling of deep sub-micron Cu\\/low-k interconnects  

Microsoft Academic Search

This paper investigates the impact of Joule heating on the scaling trends of advanced VLSI interconnects. It shows that the interconnect Joule heating can strongly affect the maximum operating temperature of the global wires which, in turn, will constrain the scaling of current density to mitigate electromigration and, thus greatly degrade the expected speed improvement from the use of low-k

Ting-Yen Chiang; B. Shieh; K. C. Saraswat

2002-01-01

81

Controlling the crystallization and magnetic properties of melt-spun Pr2Fe14B -Fe nanocomposites by Joule heating  

E-print Network

by Joule heating Z. Q. Jin School of Materials Science and Engineering, Georgia Institute of Technology by means of ac Joule heating while simultaneously monitoring room-temperature electrical resistance R the crystallization behavior during Joule heating and to identify the heat-treatment conditions for optimum magnetic

Wang, Zhong L.

82

Refractory electrodes for joule heating and methods of using same  

DOEpatents

A certain group of electrically conductive refractory materials presently known for use in high temperature applications as throat constructions, melter sidewalls, forehearth, stacks, port sills, hot face lining for slagging coal gasifiers, slag runners, and linings for nuclear waste encapsulation furnaces may be used as electrodes permitting joule heating at temperatures in excess of 1,200 C in excess of about 4400 hours even in the presence of transition group element(s). More specifically, the invention is an electrode for melting earthen materials, wherein the electrode is made from an electrically conductive refractory material, specifically at least one metal oxide wherein the metal is selected from the group consisting of chrome, ruthenium, rhodium, tin and combinations thereof. 2 figs.

Lamar, D.A.; Chapman, C.C.; Elliott, M.L.

1998-05-12

83

Refractory electrodes for joule heating and methods of using same  

DOEpatents

A certain group of electrically conductive refractory materials presently known for use in high temperature applications as throat constructions, melter sidewalls, forehearth, stacks, port sills, hot face lining for slagging coal gasifiers, slag runners, and linings for nuclear waste encapsulation furnaces may be used as electrodes permitting joule heating at temperatures in excess of 1200 C. in excess of about 4400 hours even in the presence of transition group element(s). More specifically, the invention is an electrode for melting earthen materials, wherein the electrode is made from an electrically conductive refractory material, specifically at least one metal oxide wherein the metal is selected from the group consisting of chrome, ruthenium, rhodium, tin and combinations thereof.

Lamar, David A. (West Richland, WA); Chapman, Chris C. (Richland, WA); Elliott, Michael L. (Kennewick, WA)

1998-01-01

84

Joule heating and runaway electron acceleration in a solar flare  

NASA Technical Reports Server (NTRS)

The hard and soft x ray and microwave emissions from a solar flare (May 14, 1980) were analyzed and interpreted in terms of Joule heating and runaway electron acceleration in one or more current sheets. It is found that all three emissions can be generated with sub-Dreicer electric fields. The soft x ray emitting plasma can only be heated by a single current sheet if the resistivity in the sheet is well above the classical, collisional resistivity of 10(exp 7) K, 10(exp 11)/cu cm plasma. If the hard x ray emission is from thermal electrons, anomalous resistivity or densities exceeding 3 x 10(exp 12)/cu cm are required. If the hard x ray emission is from nonthermal electrons, the emissions can be produced with classical resistivity in the current sheets if the heating rate is approximately 4 times greater than that deduced from the soft x ray data (with a density of 10(exp 10)/cu cm in the soft x ray emitting region), if there are at least 10(exp 4) current sheets, and if the plasma properties in the sheets are characteristic of the superhot plasma observed in some flares by Lin et al., and with Hinotori. Most of the released energy goes directly into bulk heating, rather than accelerated particles.

Holman, Gordon D.; Kundu, Mukul R.; Kane, Sharad R.

1989-01-01

85

An estimate of the global-scale joule heating rates in the thermosphere due to time mean currents  

Microsoft Academic Search

An estimate of the global-scale joule heating rates in the thermosphere is made based on derived global equivalent overhead electric current systems in the dynamo region during geomagnetically quiet and disturbed periods. Results show that joule heating is an important and at times the dominant energy source at high latitudes. However, global mean joule heating rates calculated near solar minimum

R. G. Roble; S. Matsushita

1975-01-01

86

On the importance of E-field variability for Joule heating in the high-latitude thermosphere  

Microsoft Academic Search

Joule heating is known to be one of the major energy sources of the upper atmosphere. Knowledge of the magnitude of this source is fundamentally important to a thorough understanding of the region's physics. However, Joule heating is currently one of the largest sources of uncertainty in the thermosphere's energy budget. In numerical models the distribution of Joule heating is

M. V. Codrescu; T. J. Fuller-Rowell; J. C. Foster

1995-01-01

87

Simulation of Power Delivery Networks with Joule Heating Effects for 3D Integration Jianyong Xie and Madhavan Swaminathan  

E-print Network

Simulation of Power Delivery Networks with Joule Heating Effects for 3D Integration Jianyong Xie Joule heating and convection effects. The finite volume formulations of DC voltage drop equation temperature distribution with convection and Joule heating effects. The simulation results show that even

Swaminathan, Madhavan

88

High-resolution spatial mapping of the temperature distribution of a Joule self-heated graphene nanoribbon  

E-print Network

High-resolution spatial mapping of the temperature distribution of a Joule self-heated graphene November 2011) We investigate the temperature distributions of Joule self-heated graphene nanoribbons (GNRs. Local temperature distributions of Joule self- heated graphene devices have been studied by optical meth

Kim, Philip

89

Collisional Joule dissipation in the ionosphere of Venus: The importance of electron heat conduction  

Microsoft Academic Search

The ionosphere of an unmagnetized planet, such as Venus, is characterized by rel- atively high Pedersen conductivity in comparison to the terrestrial ionosphere because of the weak magnetic field. Collisional Joule dissipation of plasma waves might therefore be an important source of heat within the Venus ionosphere. However, any assessment of the importance of colli- sional Joule dissipation must take

R. J. Strangeway

1996-01-01

90

Chatanika Radar Observations Relating to the Latitudinal and Local Time Variations of Joule Heating  

Microsoft Academic Search

Observations of plasma convection the complexity of the true situation and may pos- made with the Chatanika incoherent scatter radar sibly give misleading results. have been analyzed to give latitude\\/local time In a previous paper (Banks, 1977) experimental plots of the electric field contribution (E 2) to results pertaining to Joule and energetic parti- thermospheric Joule heating. The data, which

P. M. Banks; J. C. Foster; J. R. Doupnik

1981-01-01

91

Infrared Thermography applied to measurement of Heat transfer coefficient of water in a pipe heated by Joule effect  

E-print Network

Infrared Thermography applied to measurement of Heat transfer coefficient of water in a pipe heated by Joule effect by P. Leblay*, J.-F. Henry**, D. Caron**, D. Leducq*, A. Bontemps*** and L. Fournaison has been developed based on periodic excitation by Joule effect and infrared thermography measurement

Boyer, Edmond

92

Published in Physical Review B, 84 054437 (2011). Additional Material and postprint (pdf) Joule heating in nanowires  

E-print Network

, Jungiusstrasse 11, 20355 Hamburg, Germany We study the effect of Joule heating from electric currents flowing the ferromagnetic patterns. Associated with these large current densities is a substantial amount of Joule heat- ingPublished in Physical Review B, 84 054437 (2011). Additional Material and postprint (pdf) Joule

Sóbester, András

93

Free convection heat and mass transfer with Hall current, Joule heating and thermal diffusion  

Microsoft Academic Search

A boundary layer analysis has been presented to study the combined effects of viscous dissipation, Joule heating, transpiration,\\u000a heat source, thermal diffusion and Hall current on the hydromagnetic free convection and mass transfer flow of an electrically\\u000a conducting, viscous, homogeneous, incompressible fluid past an infinite vertical porous plate. The governing partial differential\\u000a equations of the hydromagnetic free convective boundary layer

Ajay Kumar Singh; Rama Subba Reddy Gorla

2009-01-01

94

Coherent radar estimates of average high-latitude ionospheric Joule heating  

SciTech Connect

The Scandinavian Twin Auroral Radar Experiment (STARE) and Sweden and Britain Radar Experiment (SABRE) bistatic coherent radar systems have been employed to estimate the spatial and temporal variation of the ionospheric Joule heating in the combined geographic latitude range 63.8 deg - 72.6 deg (corrected geomagnetic latitude 61.5 deg - 69.3 deg) over Scandinavia. The 173 days of good observations with all four radars have been analyzed during the period 1982 to 1986 to estimate the average ionospheric electric field versus time and latitude. The AE dependent empirical model of ionospheric Pedersen conductivity of Spiro et al. (1982) has been used to calculate the Joule heating. The latitudinal and diurnal variation of Joule heating as well as the estimated mean hemispherical heating of 1.7 x 10(exp 11) W are in good agreement with earlier results. Average Joule heating was found to vary linearly with the AE, AU, and AL indices and as a second-order power law with Kp. The average Joule heating was also examined as a function of the direction and magnitude of the interplanetary magnetic field. It has been shown for the first time that the ionospheric electric field magnitude as well as the Joule heating increase with increasingly negative (southward) Bz.

Kosch, M.J.; Nielsen, E. [Max-Planck-Institut fuer Aeronomie, Katlenburg-Lindau (Germany)

1995-07-01

95

Influence of moderate Joule heating on electroosmotic flow velocity, retention, and efficiency in capillary electrochromatography  

Microsoft Academic Search

The influence of Joule heating on electroosmotic flow velocity, the retention factor of neutral analytes, and separation efficiency in capillary electrochromatography was investigated theoretically and experimentally. A plot of electrical current against the applied electrical field strength was used to evaluate the Joule heating effect. When the mobile phase concentration of Tris buffer exceeded 5.0mM in the studied capillary electrochromatography

Guofang Chen; Ulrich Tallarek; Andreas Seidel-Morgenstern; Yukui Zhang

2004-01-01

96

Joule heating effect on electroosmotic flow and mass species transport in a microcapillary  

Microsoft Academic Search

This study presents a numerical analysis of Joule heating effect on the electroosmotic flow and mass species transport, which has a direct application in the capillary electrophoresis based BioChip technology. A rigorous mathematic model for describing the Joule heating in an electroosmotic flow including the Poisson–Boltzmann equation, the modified Navier–Stokes equations and the energy equation is developed. All these equations

G. Y. Tang; C. Yang; J. C. Chai; H. Q. Gong

2004-01-01

97

Rapid joule heating of metal films used to crystallize silicon films  

Microsoft Academic Search

.   We analyzed the rapid heating properties of 50-nm-thick silicon films via 250-nm-thick SiO2 intermediate layers by heat diffusion from joule heating induced by electrical current flow in chromium strips. Numerical\\u000a heat-flow simulation resulted in that the silicon films were heated to the melting point by a joule-heating intensity above\\u000a 1 MW\\/cm2. A marked increase in electrical conductance associated with silicon

T. Sameshima; Y. Kaneko; N. Andoh

2002-01-01

98

Localized Joule heating produced by ion current focusing through micron-size holes  

E-print Network

Localized Joule heating produced by ion current focusing through micron-size holes V. Viasnoff,1,a is discussed. © 2010 American Institute of Physics. doi:10.1063/1.3399315 The creation of local heat sources diffusion of heat in water. Several solutions were proposed, such as heating micro/nanoparticles1

99

A FINITE ELEMENT MODEL FOR THE TIMEDEPENDENT JOULE HEATING PROBLEM \\Lambda  

E-print Network

A FINITE ELEMENT MODEL FOR THE TIME­DEPENDENT JOULE HEATING PROBLEM \\Lambda Charles M. Elliott the electric heating of a conducting body. We prove error bounds of optimal order under minimal regularity the electric heating of a conducting body [5] with u being the temperature, OE the electric potential, and oe

Larsson, Stig

100

Joule heating effects on magnetohydrodynamic free convection flow of a micropolar fluid  

Microsoft Academic Search

An analysis is presented to study the effect of viscous and Joule heating on MHD-free convection flow with a variable plate temperature in a micropolar fluid in the presence of uniform transverse magnetic field. The presence of dissipation increases both the skin friction and the rate of heat transfer at the surface. The friction factor and heat transfer rate decrease

Rama Subba Reddy Gorla

1999-01-01

101

Decoupling electrocaloric effect from Joule heating in a solid state cooling device  

NASA Astrophysics Data System (ADS)

We report a heat dynamics analysis of the electrocaloric effect (ECE) in commercial multilayer capacitors based on BaTiO3 dielectric, a promising candidate for applications as a solid state cooling device. Direct measurements of the time evolution of the sample's temperature changes under different applied voltages allow us to decouple the contributions from Joule heating and from the ECE. Heat balance equations were used to model the thermal coupling between different parts of the system. Fingerprints of Joule heating and the ECE could be resolved at different time scales. We argue that Joule heating and the thermal coupling of the device to the environment must be carefully taken in to account in future developments of refrigeration technologies employing the ECE.

Quintero, M.; Ghivelder, L.; Gomez-Marlasca, F.; Parisi, F.

2011-12-01

102

Joule heating induced by vortex motion in a type-II superconductor  

SciTech Connect

We present experiments that determine the temperature increase in a type-II superconductor due to Joule heating induced by vortex motion. The effect of Joule heating is detected by comparing the response of the vortex lattice to fixed amplitude current steps of short (10 {mu}s) and long (4 s) duration, where the Joule heating is negligible and saturates, respectively. The thermometry is based on the temperature dependence of the voltage response of the vortex lattice to a driving current. By monitoring the temperature increase in NbSe{sub 2} samples adhered on a sapphire substrate with GE varnish we obtain the effective heat transfer coefficient between the sample and the bath and show that the heating is primarily due to the power dissipated by the vortex motion.

Xiao, Z. L.; Andrei, E. Y.; Shuk, P.; Greenblatt, M.

2001-09-01

103

Crystalline Grain Growth in the Lateral Direction for Silicon Thin Films by Electrical Current-Induced Joule Heating  

Microsoft Academic Search

Large crystalline grain growth was demonstrated for 60-nm-thick silicon films using the electrical-current-induced joule heating method. Tapered electrodes were used in order to ensure distribution of the joule heating intensity in the lateral direction along the surface in silicon strips. Melting of silicon for 17 mus caused by the joule heating resulted in the formation of 4-8-mum-long crystalline grains. The

Nobuyuki Andoh; Toshiyuki Sameshima

2002-01-01

104

Calculating Hemispheric Power and Joule Heating using Defense Meteorological Satellite Program (DMSP) F13 data  

NASA Astrophysics Data System (ADS)

Thermosphere Ionosphere Electrodynamics General Circulation Model (TIEGCM) simulates the thermosphere-ionosphere with self consistent electrodynamics. The Weimer 2005 ion convection model can be used with a parameterized model of the aurora based on the electron auroral hemispheric power. The spatial location and radius of the auroral model is adjusted with respect to the Weimer 2005 boundary for zero electric potential, but the resulting Joule heating may be an under or over estimation of the real magnetosphere-ionosphere energy transfer. To improve the auroral model so that the resulting Joule heating is relatively realistic is the ultimate aim of this project. To this end, we achieve a number of sub-goals using data from the DMSP-F13, which is in a dawn-dusk orbit. We use data from the Ion Drift Meter (IDM) to quantify the relative positions of the convection reversal boundary (CRB), the cross-track ion drift (Vy) sunward peaks, and the equatorward boundary of zero velocities (or zero electric potential) and compare them to Weimer 2005 positions for the same orbits. The electric field is estimated only from the cross-track ion velocity Vy in the dawn-dusk orbits, while the along-track ion velocity Vx is ignored. We also calculate auroral Pederson conductance using the auroral electron energy flux and mean electron energy measurements from the DMSP Special Sensor Precipitating Electron and Ion Spectrometer (SSJ/4). The hemispheric power is estimated from the electron energy flux. The Joule heating is approximately the product of the Pedersen conductance and the square of the electric field, where we include Pedersen conductance from EUV and from the aurora to estimate EUV Joule heating and particle Joule heating. Our results for a range of Bz Interplanetary Magnetic Fields (IMF Bz) values show that the hemispheric power is largest in the morning sector where the aurora is widest. The aurora mostly lies in the sunward ion flow region and thus the integrated particle Joule heating in the sunward ion flow region is higher than in the anti-sunward ion flow located in the polar cap. Thus, for the TIEGCM, the poleward edge of the aurora should be placed close to the Weimer CRB. However, the integrated total Joule heating is higher for anti-sunward ion flow in the polar cap compared to the integrated total Joule heating for the equatorward sunward ion flow, which points out the relative importance of the anti-sunward ion drifts. As for the spatially integrated total Joule heating, the values are approximately the same in the dawn and dusk regions.

Khan, M.; Emery, B. A.; Maute, A. I.

2013-12-01

105

Nonlinear effects and Joule heating in IV curves in manganites  

Microsoft Academic Search

We study the influence of the Joule effect on the nonlinear behavior of the transport I-V curves in polycrystalline samples of the manganite Pr0.8Ca0.2MnO3 by using the crystalline unit-cell parameters as an internal thermometer in x-ray and neutron diffractions. We develop a simple analytical model to estimate the temperature profile in the samples. Under the actual experimental conditions we show

Silvana Mercone; Raymond Frésard; Vincent Caignaert; Christine Martin; Damien Saurel; Charles Simon; Gilles André; Philippe Monod; François Fauth

2005-01-01

106

Strongly coupled radiative transfer and Joule heating in the cathode of an arc heater  

NASA Technical Reports Server (NTRS)

Radiation and Joule heating in the electrode region of an arc heater are discussed. Radiative transport equations for a true axisymmetric geometry are used. A subsonic code is developed to numerically solve the fluid equations with strongly coupled radiation and Joule heating representative of a high pressure and high current arc heater. Analytic expression for the divergence of radiative heat flux derived previously is used. Jacobians of the radiation term are derived. The Joule heating term is computed using a previously developed code. The equilibrium gas model consists of seven species. The fluxes are differenced using Van Leer flux splitting. Using this code, the effects of radiative cooling on the thermodynamic parameters of the arc core are discussed.

Durgapal, P.; Palmer, Grant E.

1993-01-01

107

Low-grade thermal energy-conversion Joule effect heat engines  

Microsoft Academic Search

Low-grade thermal energy conversion is discussed with attention to energy sources, heat engines, and potential Joule engine applications. Nitinol heat engine concepts are discussed, and the Nitinol equation-of-state surfaces and transition characteristics are indicated. Bottoming cycles are considered, the untapped low-temperature water energy sources are estimated, the heat-transfer limitation of gas phase heat engines is examined, and solid-state heat engines

W. S. Ginell; J. L. McNichols; J. S. Cory

1978-01-01

108

On the Role of Joule Heating as a Source of Gravity-Wave Energy above 100 km  

Microsoft Academic Search

Observations of ionospheric disturbances by various investigators have led to the suggestion that auroral energy may be coupled to atmospheric wave motions through joule heating. A linear model of internal gravity-wave generation by joule heating in the region of the auroral electrojet (100-150 km above the earth's surface) is investigated. Heat conduction, viscosity and reflection of wave energy by atmospheric

William Blumen; Richard G. Hendl

1969-01-01

109

Joule heating and determination of temperature in capillary electrophoresis and capillary electrochromatography columns  

Microsoft Academic Search

This article reviews the progress that has taken place in the past decade on the topic of estimation of Joule heating and temperature inside an open or packed capillary in electro-driven separation techniques of capillary electrophoresis (CE) and capillary electrochromatography (CEC), respectively. Developments in theoretical modeling of the heat transfer in the capillary systems have focused on attempts to apply

Anurag S. Rathore

2004-01-01

110

Joule heating by ac electric fields in the ionosphere of Venus  

Microsoft Academic Search

It is shown that Joule heating from electron collision damping of ac electric fields could be a significant source of energy for electrons in the Venus ionosphere if they occur naturally on a large scale. On the assumption that the fields are due to electromagnetic waves on a planetary scale, we calculate heating rates implied by observations on the dayside

K. D. Cole; W. R. Hoegy

1996-01-01

111

Diffusion, Fluxes, Friction Forces, and Joule Heating in Two-Temperature Multicomponent Magnetohydrodynamics  

NASA Technical Reports Server (NTRS)

The relationship between Joule heating, diffusion fluxes, and friction forces has been studied for both total and electron thermal energy equations, using general expressions for multicomponent diffusion in two-temperature plasmas with the velocity dependent Lorentz force acting on charged species in a magnetic field. It is shown that the derivation of Joule heating terms requires both diffusion fluxes and friction between species which represents the resistance experienced by the species moving at different relative velocities. It is also shown that the familiar Joule heating term in the electron thermal energy equation includes artificial effects produced by switching the convective velocity from the species velocity to the mass-weighted velocity, and thus should not be ignored even when there is no net energy dissipation.

Chang, C. H.

1999-01-01

112

Measuring Joule heating and strain induced by electrical current with Moire interferometry  

SciTech Connect

This study proposes a new method to locate and measure the temperature of the hot spots caused by Joule Heating by measuring the free thermal expansion in-plane strain. It is demonstrated that the hotspot caused by the Joule heating in a thin metal film/plate structure can be measured by Phase shifting Moire interferometry with continuous wavelet transform (PSMI/CWT) at the microscopic scale. A demonstration on a copper film is conducted to verify the theory under different current densities. A correlation between the current density and strain in two orthogonal directions (one in the direction of the current flow) is proposed. The method can also be used for the measurement of the Joule heating in the microscopic solid structures in the electronic packaging devices. It is shown that a linear relationship exists between current density squared and normal strains.

Chen Bicheng; Basaran, Cemal [Electronic Packaging Laboratory, State University of New York at Buffalo, 102 Ketter Hall, Buffalo, New York 14260 (United States)

2011-04-01

113

Controlled Formation of Zigzag and Armchair Edges in Graphene Nanoribbons by Joule Heating  

SciTech Connect

We demonstrate and monitor an efficient edge reconstruction process, at the atomic scale, for graphite nanoribbons by Joule heating inside an integrated transmission electron microscope equipped with a scanning tunneling stage STM (TEM-STM system). During Joule annealing, sharp edges and step-edge arrays are formed, mostly with either zigzag or armchair edge configurations. Their formation is driven by both thermal and electric field related mechanisms. Model calculations show that the dominant annealing mechanisms involve point defect annealing and edge reconstruction. Joule heating is thus shown to provide an effective way to produce clean zigzag and armchair edges, which could be useful for both fundamental studies of edge reactivity, magnetism, and could provide a route for increasing carrier mobility and for the development of future electronics applications.

Sumpter, Bobby G [ORNL; Dresselhaus, M [Massachusetts Institute of Technology (MIT); Terrones Maldonado, Mauricio [ORNL; Meunier, Vincent [ORNL; Romo Herrera, Jose M [ORNL; Jia, Xiaoting [Massachusetts Institute of Technology (MIT); Hofmann, Mario [Massachusetts Institute of Technology (MIT); Campos-Delgado, Jessica [IPICyT; Reina, Alfonso [Massachusetts Institute of Technology (MIT); Kong, Jing [Massachusetts Institute of Technology (MIT); Hsieh, Ya-Ping [Massachusetts Institute of Technology (MIT); Son, Hyungbin [Massachusetts Institute of Technology (MIT)

2009-01-01

114

Possible reasons for underestimating Joule heating in global models: E field variability, spatial resolution, and vertical velocity  

Microsoft Academic Search

It is important to understand Joule heating because it can significantly change the temperature structure, atmosphere composition, and electron density and hence influences satellite drag. It is thought that many coupled ionosphere-thermosphere models underestimate Joule heating because the spatial and temporal variability of the ionospheric electric field is not totally captured within global models. Using the Global Ionosphere Thermosphere Model

Yue Deng; Aaron J. Ridley

2007-01-01

115

Local temperature redistribution and structural transition during joule-heating-driven conductance switching in VO2.  

PubMed

Joule-heating induced conductance-switching is studied in VO2 , a Mott insulator. Complementary in situ techniques including optical characterization, blackbody microscopy, scanning transmission X-ray microscopy (STXM) and numerical simulations are used. Abrupt redistribution in local temperature is shown to occur upon conductance-switching along with a structural phase transition, at the same current. PMID:23868142

Kumar, Suhas; Pickett, Matthew D; Strachan, John Paul; Gibson, Gary; Nishi, Yoshio; Williams, R Stanley

2013-11-13

116

Thermal characterization of anisotropic thin dielectric films using harmonic Joule heating  

Microsoft Academic Search

A technique for thermal characterization of anisotropic dielectric films is developed. The technique is applicable to a film which has thickness of the order of 1 ?m and is on a substrate with high thermal conductivity. Metal lines with various widths are deposited on the film using standard IC fabrication processes and are subjected to harmonic Joule heating. Monitoring the

Y. S. Ju; K. Kurabayashi; K. E. Goodson

1999-01-01

117

Finite Element Convergence for the Joule Heating Problem with Mixed Boundary Conditions  

E-print Network

We prove strong convergence of conforming finite element approximations to the stationary Joule heating problem with mixed boundary conditions on Lipschitz domains in three spatial dimensions. We show optimal global regularity estimates on creased domains and prove a priori and a posteriori bounds for shape regular meshes.

Jensen, Max

2012-01-01

118

Viscous and Joule heating effects on forced convection flow from radiate isothermal porous surfaces  

Microsoft Academic Search

Purpose – To highlight the effect of viscous and Joule heating on different ionized gases in the presence of magneto and thermal radiation effects. Design\\/methodology\\/approach – The conservation equations are written for the MHD forced convection in the presence of thermal radiation. The governing equations are transformed into non-similar form using a set of dimensionless variables and then solved numerically

H. M. Duwairi

2005-01-01

119

Electrothermal coupling analysis of current crowding and Joule heating in flip-chip packages  

Microsoft Academic Search

Solder bumps serve as electrical paths as well as structural support in a flip-chip package assembly. Owing to the differences of feature sizes and electric resistivities between a solder bump and its adjacent traces, current densities around the regions where traces connect the solder bump increase in a significant amount. This current crowding effect along with the induced Joule heating

Yi-shao Lai; Chin-li Kao

2006-01-01

120

Discretization of the Joule heating term for plasma discharge fluid models in unstructured meshes  

SciTech Connect

The fluid (continuum) approach is commonly used for simulation of plasma phenomena in electrical discharges at moderate to high pressures (>10's mTorr). The description comprises governing equations for charged and neutral species transport and energy equations for electrons and the heavy species, coupled to equations for the electromagnetic fields. The coupling of energy from the electrostatic field to the plasma species is modeled by the Joule heating term which appears in the electron and heavy species (ion) energy equations. Proper numerical discretization of this term is necessary for accurate description of discharge energetics; however, discretization of this term poses a special problem in the case of unstructured meshes owing to the arbitrary orientation of the faces enclosing each cell. We propose a method for the numerical discretization of the Joule heating term using a cell-centered finite volume approach on unstructured meshes with closed convex cells. The Joule heating term is computed by evaluating both the electric field and the species flux at the cell center. The dot product of these two vector quantities is computed to obtain the Joule heating source term. We compare two methods to evaluate the species flux at the cell center. One is based on reconstructing the fluxes at the cell centers from the fluxes at the face centers. The other recomputes the flux at the cell center using the common drift-diffusion approximation. The reconstructed flux scheme is the most stable method and yields reasonably accurate results on coarse meshes.

Deconinck, T.; Mahadevan, S. [Dept. of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712 (United States); Raja, L.L. [Dept. of Aerospace Engineering and Engineering Mechanics, University of Texas at Austin, Austin, TX 78712 (United States)], E-mail: lraja@mail.utexas.edu

2009-07-01

121

Electrothermal coupling analysis of current crowding and Joule heating in flip-chip package assembly  

Microsoft Academic Search

Solder bumps serve as electrical paths as well as structural support in a flip-chip package assembly. Owing to the differences of feature sizes and electric resistivities between a solder bump and its adjacent traces, current densities around the regions where traces connect the solder bump increase in a significant amount. This current crowding effect along with the induced Joule heat

Chin-Li Kao; Yi-Shao Lai

2004-01-01

122

Experimental evidence in support of Joule heating associated with geomagnetic activity  

NASA Technical Reports Server (NTRS)

High resolution accelerometer measurements in the altitude region 140 to 300 km from a satellite in a near-polar orbit during a period of extremely high geomagnetic activity indicate that Joule heating is the primary source of energy for atmospheric heating associated with geomagnetic activity. This conclusion is supported by the following observational evidence: (1) There is an atmospheric response in the auroral zone which is nearly simulataneous with the onset of geomagnetic activity, with no significant response in the equatorial region until several hours later; (2) The maximum heating occurs at geographic locations near the maximum current of the auroral electrojet; and (3) There is evidence of atmospheric waves originating near the auroral zone at altitudes where Joule heating would be expected to occur. An analysis of atmospheric response time to this heat shows time delays are apparently independent of altitude but are strongly dependent upon geomagnetic latitude.

Devries, L. L.

1971-01-01

123

Joule heat generation in thermionic cathodes of high-pressure arc discharges  

SciTech Connect

The nonlinear surface heating model of plasma-cathode interaction in high-pressure arcs is extended to take into account the Joule effect inside the cathode body. Calculation results are given for different modes of current transfer to tungsten cathodes of different configurations in argon plasmas of atmospheric or higher pressures. Special attention is paid to analysis of energy balances of the cathode and the near-cathode plasma layer. In all the cases, the variation of potential inside the cathode is much smaller than the near-cathode voltage drop. However, this variation can be comparable to the volt equivalent of the energy flux from the plasma to the cathode and then the Joule effect is essential. Such is the case of the diffuse and mixed modes on rod cathodes at high currents, where the Joule heating causes a dramatic change of thermal and electrical regimes of the cathode. The Joule heating has virtually no effect over characteristics of spots on rod and infinite planar cathodes.

Benilov, M. S.; Cunha, M. D. [Departamento de Fisica, CCCEE, Universidade da Madeira, Largo do Municipio, 9000 Funchal (Portugal)

2013-02-14

124

Joule heat generation in thermionic cathodes of high-pressure arc discharges  

NASA Astrophysics Data System (ADS)

The nonlinear surface heating model of plasma-cathode interaction in high-pressure arcs is extended to take into account the Joule effect inside the cathode body. Calculation results are given for different modes of current transfer to tungsten cathodes of different configurations in argon plasmas of atmospheric or higher pressures. Special attention is paid to analysis of energy balances of the cathode and the near-cathode plasma layer. In all the cases, the variation of potential inside the cathode is much smaller than the near-cathode voltage drop. However, this variation can be comparable to the volt equivalent of the energy flux from the plasma to the cathode and then the Joule effect is essential. Such is the case of the diffuse and mixed modes on rod cathodes at high currents, where the Joule heating causes a dramatic change of thermal and electrical regimes of the cathode. The Joule heating has virtually no effect over characteristics of spots on rod and infinite planar cathodes.

Benilov, M. S.; Cunha, M. D.

2013-02-01

125

Stabilization of the no-motion state of a horizontal fluid layer heated from below with Joule heating  

Microsoft Academic Search

Using linear stability theory and numerical simulations, we demonstrate that the critical Rayleigh number for bifurcation from the no-motion (conduction) state to the motion state in the Rayleigh-Benard problem of an infinite fluid layer heated from below with Joule heating and cooled from above can be significantly increased through the use of feedback control strategies effecting small perturbations in the

J. Tang; H. H. Bau

1995-01-01

126

Electroosmotic flow with Joule heating effects Xiangchun Xuan,a Bo Xu,a David Sintonb and Dongqing Li*a  

E-print Network

Electroosmotic flow with Joule heating effects Xiangchun Xuan,a Bo Xu,a David Sintonb and Dongqing Electroosmotic flow with Joule heating effects was examined numerically and experimentally in this work. We used a fluorescence-based thermometry technique to measure the liquid temperature variation caused by Joule heating

Xuan, Xiangchun "Schwann"

127

Remote Joule heating by a carbon nanotube Kamal H. Baloch1, Norvik Voskanian1, Merijntje Bronsgeest2 and John Cumings1  

E-print Network

Remote Joule heating by a carbon nanotube Kamal H. Baloch1, Norvik Voskanian1, Merijntje Bronsgeest2 and John Cumings1 * Minimizing Joule heating remains an important goal in the design of electronic devices1,2 . The prevailing model of Joule heating relies on a simple semiclassical picture in which elec

Li, Teng

128

On the influence of Joule heating induced nanocrystallization on structural and magnetic properties of Co64Fe21B15 alloy  

E-print Network

1 On the influence of Joule heating induced nanocrystallization on structural and magnetic. Wilson, 94235 Cachan cedex, France Abstract Structural and magnetic properties of Joule heated Co64Fe21B15 alloy has been studied. Crystallization of the specimens starts after Joule heating with 1

Paris-Sud XI, Université de

129

Local Joule heating and overall resistance increase in void-containing aluminum interconnects  

Microsoft Academic Search

Local Joule heating and the overall resistance change due to void formation in aluminum interconnects were studied numerically.\\u000a In the model the TiN\\/Al\\/TiN metallization stack is embedded within the SiO2 dielectric. Three-dimensional finite element analyses, taking into account the current shunting into the barrier layer and\\u000a the coupling between heat conduction and electrical conduction, were carried out. The temperature field

Y.-L. SHEN

2001-01-01

130

Joule heating effect of electroosmosis in a finite-length microchannel made of different materials  

Microsoft Academic Search

This paper presents a numerical analysis of Joule heating effect of electroosmosis in a finite-length microchannel made of\\u000a the glass and polydimethylsiloxane (PDMS) polymer. The Poisson-Boltzmann equation of electric double layer, the Navier-Stokes\\u000a equation of liquid flow, and the liquid-solid coupled heat transfer equation are solved to investigate temperature behaviors\\u000a of electroosmosis in a two-dimensional microchannel. The feedback effect of

Kan Chao; Jian-kang Wu; Bo Chen

2010-01-01

131

Local Joule heating and overall resistance increase in void-containing aluminum interconnects  

Microsoft Academic Search

Local Joule heating and the overall resistance change due to void formation in aluminum interconnects were studied numerically. In the model the TiN\\/Al\\/TiN metallization stack is embedded within the SiO2 dielectric. Three-dimensional finite element analyses, taking into account the current shunting into the barrier layer and the coupling between heat conduction and electrical conduction, were carried out. The temperature field

Y. L. Shen

2001-01-01

132

The equivalence of Joule dissipation and frictional heating in the collisional ionosphere  

NASA Astrophysics Data System (ADS)

We address what is meant by Joule dissipation in the context of the coupled magnetosphere-ionosphere-thermosphere system. We first show that the ionospheric Ohm's law that includes the classical Pedersen and Hall conductivities can be extended to include other terms such as plasma inertia and pressure. Within the ionosphere the Pedersen and Hall conductivities usually dominate. We note, however, that this does not mean that the electric field causes the currents. We next investigate the role of friction in heating the different species within the plasma. The frictional electron-ion collisional heating rate is proportional to j2, where j is the current density, and as such could be considered to be Ohmic in nature. The heating from electron-neutral collisions can be recast to include a term that includes j2, but only part of the electron collisional heating is Ohmic in the sense that it depends on j2. We also show that the Joule dissipation in the neutral frame equals the total amount of frictional heating for all the fluids (electrons, ions, and neutrals) with additional terms to account for the rate at which work is done by pressure gradient forces, and the power used to accelerate the plasma. In general, these additional terms are small within the ionosphere, and most of the Joule dissipation in the neutral frame results in heating, mainly by initially increasing the ion fluid temperature relative to the neutrals, while the neutral atmosphere temperature increases with a much slower rate.

Strangeway, Robert J.

2012-02-01

133

Micro-scale heat-exchangers for Joule-Thomson cooling.  

SciTech Connect

This project focused on developing a micro-scale counter flow heat exchangers for Joule-Thomson cooling with the potential for both chip and wafer scale integration. This project is differentiated from previous work by focusing on planar, thin film micromachining instead of bulk materials. A process will be developed for fabricating all the devices mentioned above, allowing for highly integrated micro heat exchangers. The use of thin film dielectrics provides thermal isolation, increasing efficiency of the coolers compared to designs based on bulk materials, and it will allow for wafer-scale fabrication and integration. The process is intended to implement a CFHX as part of a Joule-Thomson cooling system for applications with heat loads less than 1mW. This report presents simulation results and investigation of a fabrication process for such devices.

Gross, Andrew John

2014-01-01

134

Breakdown of Richardson's law in electron emission from individual self-Joule-heated carbon nanotubes.  

PubMed

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) and temperature (T) of individual self-Joule-heated CNTs are simultaneously determined. Experimental ln(J/T(2)) - 1/T plots are found to exhibit an upward bending feature deviating from the straight lines in Richardson plots, and the measured electron emission density is more than one order of magnitude higher than that predicted by Richardson's law. The breakdown of Richardson's law implies a much better electron emission performance of individual CNTs as compared to their macroscopic allotropes and clusters, and the need of new theoretical descriptions of electron emission from individual low-dimensional nanostructures. PMID:24869719

Wei, Xianlong; Wang, Sheng; Chen, Qing; Peng, Lianmao

2014-01-01

135

Breakdown of Richardson's Law in Electron Emission from Individual Self-Joule-Heated Carbon Nanotubes  

NASA Astrophysics Data System (ADS)

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) and temperature (T) of individual self-Joule-heated CNTs are simultaneously determined. Experimental ln(J/T2) - 1/T plots are found to exhibit an upward bending feature deviating from the straight lines in Richardson plots, and the measured electron emission density is more than one order of magnitude higher than that predicted by Richardson's law. The breakdown of Richardson's law implies a much better electron emission performance of individual CNTs as compared to their macroscopic allotropes and clusters, and the need of new theoretical descriptions of electron emission from individual low-dimensional nanostructures.

Wei, Xianlong; Wang, Sheng; Chen, Qing; Peng, Lianmao

2014-05-01

136

Modeling Joule Heating Effect on Lunar O2 Generation via Electrolytic Reduction.  

NASA Technical Reports Server (NTRS)

Kennedy Space Center is leading research work on lunar O2 generation via electrolytic reduction of regolith; the metal oxide present in the regolith is dissociated in oxygen anions and metal cations leading to the generation of gaseous oxygen at the anode and liquid metal at the cathode. Electrical resistance of molten regolith is high, leading to heating of the melt when electrical current is applied between the electrodes (Joule heating). The authors have developed a 3D model using a rigorous approach for two coupled physics (thermal and electrical potential) to not only study the effect of Joule heating on temperature distribution throughout the molten regolith but also to evaluate and optimize the design of the electrolytic cells. This paper presents the results of the thermal analysis performed on the model and used to validate the design of the electrolytic cell.

Dominquez, Jesus; Poizeau, Sophie; Sibille, Laurent

2009-01-01

137

Breakdown of Richardson's Law in Electron Emission from Individual Self-Joule-Heated Carbon Nanotubes  

PubMed Central

Probing the validity of classical macroscopic physical laws at the nanoscale is important for nanoscience research. Herein, we report on experimental evidence that electron emission from individual hot carbon nanotubes (CNTs) heated by self-Joule-heating does not obey Richardson's law of thermionic emission. By using an in-situ multi-probe measurement technique, electron emission density (J) and temperature (T) of individual self-Joule-heated CNTs are simultaneously determined. Experimental ln(J/T2) ? 1/T plots are found to exhibit an upward bending feature deviating from the straight lines in Richardson plots, and the measured electron emission density is more than one order of magnitude higher than that predicted by Richardson's law. The breakdown of Richardson's law implies a much better electron emission performance of individual CNTs as compared to their macroscopic allotropes and clusters, and the need of new theoretical descriptions of electron emission from individual low-dimensional nanostructures. PMID:24869719

Wei, Xianlong; Wang, Sheng; Chen, Qing; Peng, Lianmao

2014-01-01

138

Joule heating effects in electroosmotically driven microchannel flows  

Microsoft Academic Search

Analytical solutions for temperature distributions, heat transfer coefficients, and Nusselt numbers of steady electroosmotic flows are obtained for two-dimensional straight microchannels. This analysis is based on an infinitesimal electric double layer in which flow velocity becomes “plug-like”, except very close to the wall. Both constant surface temperature and constant surface heat flux conditions are considered in this study. Separation of

Keisuke Horiuchi; Prashanta Dutta

2004-01-01

139

Jupiter Thermospheric General Circulation Model (JTGCM): Global Structure and Dynamics Driven by Auroral and Joule Heating  

NASA Technical Reports Server (NTRS)

A growing multispectral database plus recent Galileo descent measurements are being used to construct a self-consistent picture of the Jupiter thermosphere/ionosphere system. The proper characterization of Jupiter s upper atmosphere, embedded ionosphere, and auroral features requires the examination of underlying processes, including the feedbacks of energetics, neutral-ion dynamics, composition, and magnetospheric coupling. A fully 3-D Jupiter Thermospheric General Circulation Model (JTGCM) has been developed and exercised to address global temperatures, three-component neutral winds, and neutral-ion species distributions. The domain of this JTGCM extends from 20-microbar (capturing hydrocarbon cooling) to 1.0 x 10(exp -4) nbar (including aurora/Joule heating processes). The resulting JTGCM has been fully spun-up and integrated for greater than or equal to40 Jupiter rotations. Results from three JTGCM cases incorporating moderate auroral heating, ion drag, and moderate to strong Joule heating processes are presented. The neutral horizontal winds at ionospheric heights vary from 0.5 km/s to 1.2 km/s, atomic hydrogen is transported equatorward, and auroral exospheric temperatures range from approx.1200-1300 K to above 3000 K, depending on the magnitude of Joule heating. The equatorial temperature profiles from the JTGCM are compared with the measured temperature structure from the Galileo AS1 data set. The best fit to the Galileo data implies that the major energy source for maintaining the equatorial temperatures is due to dynamical heating induced by the low-latitude convergence of the high-latitude-driven thermospheric circulation. Overall, the Jupiter thermosphere/ionosphere system is highly variable and is shown to be strongly dependent on magnetospheric coupling which regulates Joule heating.

Bougher, S. W.; J. Il. Waite, Jr.; Majeed, T.

2005-01-01

140

Joule heating in the mesosphere and thermosphere during the July 13, 1982, solar proton event  

NASA Technical Reports Server (NTRS)

The solar proton event of July 13, 1982 produced considerable ionization in the polar-cap mesosphere. Energetic solar proton fluxes were measured by the NOAA-6 satellite. The DE-2 satellite measured the low-energy electrons, the ion drift velocity, and other atmospheric and ionospheric properties during the event in the region of the measured maximum electric field (189 mV/m at 2215 UT near 60 deg N), a Joule heating rate of 1-3 K/day is calculated between 70 and 80 km, exceeding the heating due to ozone absorption at noon in the summer hemisphere in that altitude range. The Joule heating rate above 90 km greatly exceeded 20 K/day. The calculated height-integrated Joule heating rate above 100 km in the same region exceeded 400 ergs/sq cm sec, and DE-2 near 350 km measured neutral winds of nearly 1000 m/s and neutral gas temperatures of over 2000 K. The overall ionospheric structure calculated below the DE-2 satellite is described.

Roble, R. G.; Emery, B. A.; Garcia, R. R.; Killeen, T. L.; Hays, P. B.; Reid, G. C.; Solomon, S.; Evans, D. S.; Spencer, N. W.; Brace, L. H.

1987-01-01

141

Combined influences of viscous dissipation, non-uniform Joule heating and variable thermophysical properties on convective heat transfer in microtubes  

Microsoft Academic Search

This study presents a comprehensive investigation on hydrodynamic and thermal transport properties of mixed electroosmotically and pressure driven flow in microtubes. Particular emphasis is given to investigating the combined consequences of viscous dissipation, non-uniform Joule heating, and variable thermophysical properties. Analytical solutions are obtained using the Debye–Hückel linearization and constant fluid properties assumption, while a numerical solution is presented for

Hadi Yavari; Arman Sadeghi; Mohammad Hassan Saidi; Suman Chakraborty

142

Role of joule heating in electrically-driven metal insulator transition in vanadium oxide nanowires  

NASA Astrophysics Data System (ADS)

Metal to insulator transition (MIT) in vanadium oxide system can be triggered by several external stimuli such as temperature, electric field, strain and light. Electrically driven MIT in single nanowire devices of crystalline vanadium oxide (W- doped VO2, Ag-doped V2O5) is the topic of current study. Recent works on realizing switching devices using these materials have discussed the importance of Joule heating near the transition as supposed to a purely electric field induced effect. We propose a novel method for identifying the individual roles of Joule heating and/or electric field by analyzing the frequency response of the AC electric signal near the MIT in these devices. The method may also be used in other strongly correlated electron system to delineate the roles of individual microscopic conduction mechanisms near MIT.

Singh, Sujay; Shi, Zhenzhong; Kwan, Chun Pui; Marley, Peter; Banerjee, Sarbajit; Sambandamurthy, Ganapathy

2013-03-01

143

The neutron star in Cassiopeia A: equation of state, superfluidity, and Joule heating  

E-print Network

The thermomagnetic evolution of the young neutron star in Cassiopea A is studied by considering fast neutrino emission processes. In particular, we consider neutron star models obtained from the equation of state computed in the framework of the Brueckner-Bethe-Goldstone many-body theory and variational methods, and models obtained with the Akmal-Pandharipande-Ravenhall equation of state. It is shown that it is possible to explain a fast cooling regime as the one observed in the neutron star in Cassiopea A if the Joule heating produced by dissipation of the small-scale magnetic field in the crust is taken into account. We thus argue that it is difficult to put severe constraints on the superfluid gap if the Joule heating is considered.

Bonanno, A; Burgio, G F; Urpin, V

2013-01-01

144

Energy transfer to a wire from a surrounding Joule-heated corona  

Microsoft Academic Search

This paper considers the early behavior of the current-carrying coronal plasma formed around the relatively colder liquid-vapor\\u000a core of a wire. This has applications to both a wire array before global effects dominate and a single wire. An analytic,\\u000a theoretical model is developed where the Joule heating in the coronal plasma is thermally conducted to the cold core. The\\u000a balance

M. G. Haines

2003-01-01

145

On the temperature distributions around dislocations in III-V compounds due to Joule heating  

Microsoft Academic Search

The nonuniform rate of creation of Joule heat due to variations in the electrical conductivity around dislocations in III-V compounds gives rise to variations in the temperature around these dislocations. The general equations and boundary conditions for this temperature distribution are derived for any III-V compound. The specific temperature distributions around 60° and edge dislocations in n-type GaSb are calculated.

H. Booyens; J. S. Vermaak; G. R. Proto

1978-01-01

146

Pulsed laser-induced electrical-current joule heating for crystallization of silicon thin films  

Microsoft Academic Search

50 nm-amorphous silicon films were crystallized by the pulsed laser-induced electrical-current joule heating method. Holes with diameter of 6 mum were formed within silicon strips, in order to control the position of the formation of crystalline grains. Large crystalline grains of 10 mum were formed between the holes in lateral direction from the observation of the photograph of the optical

Nobuyuki Andoh; Toshiyuki Sameshima

2004-01-01

147

Effect of Joule heating in current-driven domain wall motion  

Microsoft Academic Search

It was found that high current density needed for the current-driven domain wall motion results in the Joule heating of the sample. The sample temperature, when the current-driven domain wall motion occurred, was estimated by measuring the sample resistance during the application of a pulsed current. The sample temperature was 750 K for the threshold current density of 6.7×1011 A\\/m2

A. Yamaguchi; S. Nasu; H. Tanigawa; T. Ono; K. Miyake; K. Mibu; T. Shinjo

2005-01-01

148

In situ transmission electron microscopy of individual carbon nanotetrahedron/nanoribbon structures in Joule heating  

NASA Astrophysics Data System (ADS)

Collapse of a carbon nanotube results in the formation of a nanoribbon, and a switching of the collapse direction yields a nanotetrahedron in the middle of a nanoribbon. Here, we report in-situ transmission electron microscopy observations of the behavior of carbon nanotetrahedron/nanoribbon structures during Joule heating to reveal their thermal stability. In addition, we propose that the observed process is related to the formation process of the structure.

Masuda, Yusuke; Yoshida, Hideto; Takeda, Seiji; Kohno, Hideo

2014-08-01

149

Coherent radar estimates of average high-latitude ionospheric Joule heating  

Microsoft Academic Search

The Scandinavian Twin Auroral Radar Experiment (STARE) and Sweden and Britain Radar Experiment (SABRE) bistatic coherent radar systems have been employed to estimate the spatial and temporal variation of the ionospheric Joule heating in the combined geographic latitude range 63.8 deg - 72.6 deg (corrected geomagnetic latitude 61.5 deg - 69.3 deg) over Scandinavia. The 173 days of good observations

M. J. Kosch; E. Nielsen

1995-01-01

150

The role of Joule heating in the formation of nanogaps by electromigration  

Microsoft Academic Search

We investigate the formation of nanogaps in gold wires due to\\u000aelectromigration. We show that the breaking process will not start until a\\u000alocal temperature of typically 400 K is reached by Joule heating. This value is\\u000arather independent of the temperature of the sample environment (4.2-295 K).\\u000aFurthermore, we demonstrate that the breaking dynamics can be controlled by\\u000aminimizing

M. L. Trouwborst; S. J. van der Molen; B. J. van Wees

2005-01-01

151

Programmable mechanical resonances in MEMS by localized joule heating of phase change materials.  

PubMed

A programmable micromechanical resonator based on a VO2 thin film is reported. Multiple mechanical eigenfrequency states are programmed using Joule heating as local power source, gradually driving the phase transition of VO2 around its Metal-Insulator transition temperature. Phase coexistence of domains is used to tune the stiffness of the device via local control of internal stresses and mechanical properties. This study opens perspectives for developing mechanically configurable nanostructure arrays. PMID:24038351

Manca, Nicola; Pellegrino, Luca; Kanki, Teruo; Yamasaki, Syouta; Tanaka, Hidekazu; Siri, Antonio Sergio; Marré, Daniele

2013-11-26

152

Joule-Heated Molten Regolith Electrolysis Reactor Concepts for Oxygen and Metals Production on the Moon and Mars  

NASA Technical Reports Server (NTRS)

The maturation of Molten Regolith Electrolysis (MRE) as a viable technology for oxygen and metals production on explored planets relies on the realization of the self-heating mode for the reactor. Joule heat generated during regolith electrolysis creates thermal energy that should be able to maintain the molten phase (similar to electrolytic Hall-Heroult process for aluminum production). Self-heating via Joule heating offers many advantages: (1) The regolith itself is the crucible material, it protects the vessel walls (2) Simplifies the engineering of the reactor (3) Reduces power consumption (no external heating) (4) Extends the longevity of the reactor. Predictive modeling is a tool chosen to perform dimensional analysis of a self-heating reactor: (1) Multiphysics modeling (COMSOL) was selected for Joule heat generation and heat transfer (2) Objective is to identify critical dimensions for first reactor prototype.

Sibille, Laurent; Dominques, Jesus A.

2012-01-01

153

A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect: a simulation study  

NASA Astrophysics Data System (ADS)

A 3D reconstruction solution to ultrasound Joule heat density tomography based on acousto-electric effect by deconvolution is proposed for noninvasive imaging of biological tissue. Compared with ultrasound current source density imaging, ultrasound Joule heat density tomography doesn't require any priori knowledge of conductivity distribution and lead fields, so it can gain better imaging result, more adaptive to environment and with wider application scope. For a general 3D volume conductor with broadly distributed current density field, in the AE equation the ultrasound pressure can't simply be separated from the 3D integration, so it is not a common modulation and basebanding (heterodyning) method is no longer suitable to separate Joule heat density from the AE signals. In the proposed method the measurement signal is viewed as the output of Joule heat density convolving with ultrasound wave. As a result, the internal 3D Joule heat density can be reconstructed by means of Wiener deconvolution. A series of computer simulations set for breast cancer imaging applications, with consideration of ultrasound beam diameter, noise level, conductivity contrast, position dependency and size of simulated tumors, have been conducted to evaluate the feasibility and performance of the proposed reconstruction method. The computer simulation results demonstrate that high spatial resolution 3D ultrasound Joule heat density imaging is feasible using the proposed method, and it has potential applications to breast cancer detection and imaging of other organs.

Yang, R.; Song, A.; Li, X. D.; Lu, Y.; Yan, R.; Xu, B.; Li, X.

2014-10-01

154

Pulsed laser-induced electrical-current joule heating for crystallization of silicon thin films  

NASA Astrophysics Data System (ADS)

50 nm-amorphous silicon films were crystallized by the pulsed laser-induced electrical-current joule heating method. Holes with diameter of 6 ?m were formed within silicon strips, in order to control the position of the formation of crystalline grains. Large crystalline grains of 10 ?m were formed between the holes in lateral direction from the observation of the photograph of the optical microscopy. Two dimensional heat flow simulation suggested that a temperature gradient was the ~1 x 105 K/cm.

Andoh, Nobuyuki; Sameshima, Toshiyuki

2004-10-01

155

Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars  

NASA Astrophysics Data System (ADS)

We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvénic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvénic sectors, while no bow shock forms in the sub-Alfvénic sectors. The planets reside most of the time in the sub-Alfvénic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the intense stellar wind. For the steady-state solution, the heating is about 0.1%-3% of the total incoming stellar irradiation, and it is enhanced by 50% for the time-dependent case. The significant Joule Heating obtained here should be considered in models for the atmospheres of habitable planets in terms of the thickness of the atmosphere, the top-side temperature and density, the boundary conditions for the atmospheric pressure, and particle radiation and transport. Here we assume constant ionospheric Pedersen conductance similar to that of the Earth. The conductance could be greater due to the intense EUV radiation leading to smaller heating rates. We plan to quantify the ionospheric conductance in future study.

Cohen, O.; Drake, J. J.; Glocer, A.; Garraffo, C.; Poppenhaeger, K.; Bell, J. M.; Ridley, A. J.; Gombosi, T. I.

2014-07-01

156

In situ monitoring of Joule heating effects in germanium nanowires by ?-Raman spectroscopy.  

PubMed

We explored a noninvasive optical method to determine the Joule heating of individual germanium nanowires. Using confocal ?-Raman spectroscopy, variations in the optical phonon frequency, in detail the downshifting of the first-order Stokes Raman band, are correlated to the temperature increase of vapor-liquid-solid grown germanium nanowires under an applied electrical bias. The germanium nanowires were found to handle high threshold current densities of more than 10(6) A cm(-2) before sustaining immediate deterioration. Failure of single crystalline germanium nanowires was directly observed when the applied electric field reached the breakdown point of 1.25 × 10(5) V cm(-1). PMID:23324520

Lugstein, Alois; Miji?, Mario; Burchhart, Thomas; Zeiner, Clemens; Langegger, Rupert; Schneider, Michael; Schmid, Ulrich; Bertagnolli, Emmerich

2013-02-15

157

Neutron star long term cooling - Joule heating in magnetized neutron stars  

E-print Network

We present two-dimensional simulations for the cooling of neutron stars with strong magnetic fields (B > 1e13 Gauss). We study how the cooling curves are influenced by magnetic field decay. We show that the Joule heating effects are very large and in some cases control the thermal evolution. We characterize the temperature anisotropy induced by the magnetic field and predict the surface temperature distribution for the early and late stages of the evolution of isolated neutron stars, comparing our results with available observational data of isolated neutron stars.

Deborah N. Aguilera; José A. Pons; Juan A. Miralles

2008-03-04

158

Numerical modeling of Joule heating effects in insulator-based dielectrophoresis microdevices.  

PubMed

Insulator-based DEP (iDEP) has been established as a powerful tool for manipulating particles in microfluidic devices. However, Joule heating may become an issue in iDEP microdevices due to the local amplification of electric field around the insulators. This results in an electrothermal force that can manifest itself in the flow field in the form of circulations, thus affecting the particle motion. We develop herein a transient, 3D, full-scale numerical model to study Joule heating and its effects on the coupled transport of charge, heat, and fluid in an iDEP device with a rectangular constriction microchannel. This model is validated by comparing the simulation results with the experimentally obtained fluid flow patterns and particle images that were reported in our recent works. It identifies a significant difference in the time scales of the electric, temperature, and flow fields in iDEP microdevices. It also predicts the locations of electrothermal flow circulations in different halves of the channel at the upstream and downstream of the constriction. PMID:23192532

Kale, Akshay; Patel, Saurin; Hu, Guoqing; Xuan, Xiangchun

2013-03-01

159

Magnetospheric Structure and Atmospheric Joule Heating of Habitable Planets Orbiting M-dwarf Stars  

E-print Network

We study the magnetospheric structure and the ionospheric Joule Heating of planets orbiting M-dwarf stars in the habitable zone using a set of magnetohydrodynamic (MHD) models. The stellar wind solution is used to drive a model for the planetary magnetosphere, which is coupled with a model for the planetary ionosphere. Our simulations reveal that the space environment around close-in habitable planets is extreme, and the stellar wind plasma conditions change from sub- to super-Alfvenic along the planetary orbit. As a result, the magnetospheric structure changes dramatically with a bow shock forming in the super-Alfvenic sectors, while no bow shock forms in the sub-Alfvenic sectors. The planets reside most of the time in the sub-Alfvenic sectors with poor atmospheric protection. A significant amount of Joule Heating is provided at the top of the atmosphere as a result of the planetary interaction with the stellar wind. For the steady-state solution, the heating is about 0.1-3\\% of the total incoming stellar ir...

Cohen, O; Glocer, A; Garraffo, C; Poppenhaeger, K; Bell, J M; Ridley, A J; Gombosi, T I

2014-01-01

160

3D noninvasive ultrasound Joule heat tomography based on acousto-electric effect using unipolar pulses: a simulation study  

PubMed Central

Electrical properties of biological tissues are highly sensitive to their physiological and pathological status. Thus it is of importance to image electrical properties of biological tissues. However, spatial resolution of conventional electrical impedance tomography (EIT) is generally poor. Recently, hybrid imaging modalities combining electric conductivity contrast and ultrasonic resolution based on acouto-electric effect has attracted considerable attention. In this study, we propose a novel three-dimensional (3D) noninvasive ultrasound Joule heat tomography (UJHT) approach based on acouto-electric effect using unipolar ultrasound pulses. As the Joule heat density distribution is highly dependent on the conductivity distribution, an accurate and high resolution mapping of the Joule heat density distribution is expected to give important information that is closely related to the conductivity contrast. The advantages of the proposed ultrasound Joule heat tomography using unipolar pulses include its simple inverse solution, better performance than UJHT using common bipolar pulses and its independence of any priori knowledge of the conductivity distribution of the imaging object. Computer simulation results show that using the proposed method, it is feasible to perform a high spatial resolution Joule heat imaging in an inhomogeneous conductive media. Application of this technique on tumor scanning is also investigated by a series of computer simulations. PMID:23123757

Yang, Renhuan; Li, Xu; Song, Aiguo; He, Bin; Yan, Ruqiang

2012-01-01

161

Crystalline Grain Growth in the Lateral Direction for Silicon Thin Films by Electrical Current-Induced Joule Heating  

NASA Astrophysics Data System (ADS)

Large crystalline grain growth was demonstrated for 60-nm-thick silicon films using the electrical-current-induced joule heating method. Tapered electrodes were used in order to ensure distribution of the joule heating intensity in the lateral direction along the surface in silicon strips. Melting of silicon for 17 ?s caused by the joule heating resulted in the formation of 4-8-?m-long crystalline grains. The change in the film thickness was at most 6 nm in the crystallized region. There was a tensile stress of 5.6 × 108 Pa in the film. The heat flow simulation demonstrated that the solidification occurred in the lateral direction according to the temperature gradient and that the solid/liquid interface moved in the lateral direction at the velocity of about 1-2 m/s.

Andoh, Nobuyuki; Sameshima, Toshiyuki

2002-09-01

162

Nanoscale Joule heating and electromigration enhanced ripening of silver nanowire contacts.  

PubMed

Solution-processed metallic nanowire thin film is a promising candidate to replace traditional indium tin oxide as the next-generation transparent and flexible electrode. To date however, the performance of these electrodes is limited by the high contact resistance between contacting nanowires; so improving the point contacts between these nanowires remains a major challenge. Existing methods for reducing the contact resistance require either a high processing power, long treatment time, or the addition of chemical reagents, which could lead to increased manufacturing cost and damage the underlying substrate or device. Here, a nanoscale point reaction process is introduced as a fast and low-power-consumption way to improve the electrical contact properties between metallic nanowires. This is achieved via current-assisted localized joule heating accompanied by electromigration. Localized joule heating effectively targets the high-resistance contact points between nanowires, leading to the automatic removal of surface ligands, welding of contacting nanowires, and the reshaping of the contact pathway between the nanowires to form a more desirable geometry of low resistance for interwire conduction. This result shows the interplay between thermal and electrical interactions at the highly reactive nanocontacts and highlights the control of the nanoscale reaction as a simple and effective way of turning individual metallic nanowires into a highly conductive interconnected nanowire network. The temperature of the adjacent device layers can be kept close to room temperature during the process, making this method especially suitable for use in devices containing thermally sensitive materials such as polymer solar cells. PMID:24517263

Song, Tze-Bin; Chen, Yu; Chung, Choong-Heui; Yang, Yang Michael; Bob, Brion; Duan, Hsin-Sheng; Li, Gang; Tu, King-Ning; Huang, Yu; Yang, Yang

2014-03-25

163

Joule-Heating-Induced Damage in Cu-Al Wedge Bonds Under Current Stressing  

NASA Astrophysics Data System (ADS)

Copper wires are increasingly used to replace gold wires in wire-bonding technology owing to their better electrical properties and lower cost. However, not many studies have been conducted on electromigration-induced failure of Cu wedge bonds on Al metallization. In this study, we investigated the failure mechanism of Cu-Al wedge bonds under high current stressing from 4 × 104 A/cm2 to 1 × 105 A/cm2 at ambient temperature of 175°C. The resistance evolution of samples during current stressing and the microstructure of the joint interface between the Cu wire and Al-Si bond pad were examined. The results showed that abnormal crack formation accompanying significant intermetallic compound growth was observed at the second joint of the samples, regardless of the direction of electric current for both current densities of 4 × 104 A/cm2 and 8 × 104 A/cm2. We propose that this abnormal crack formation at the second joint is mainly due to the higher temperature induced by the greater Joule heating at the second joint for the same current stressing, because of its smaller bonded area compared with the first joint. The corresponding fluxes induced by the electric current and chemical potential difference between Cu and Al were calculated and compared to explain the failure mechanism. For current density of 1 × 105 A/cm2, the Cu wire melted within 0.5 h owing to serious Joule heating.

Yang, Tsung-Han; Lin, Yu-Min; Ouyang, Fan-Yi

2014-01-01

164

I. Lackovi et al.: Three-dimensional Finite-element Analysis of Joule Heating in Electrochemotherapy and in vivo 1070-9878/09/$25.00 2009 IEEE  

E-print Network

I. Lackovi et al.: Three-dimensional Finite-element Analysis of Joule Heating of Joule Heating in Electrochemotherapy and in vivo Gene Electrotransfer Igor Lackovi, Ratko Magjarevi a comprehensive analysis of tissue heating as a potential side effect of electric pulses used for electroporation

Ljubljana, University of

165

Direct Evidence of Molecular Aggregation and Degradation Mechanism of Organic Light-Emitting Diodes under Joule Heating: an STM and Photoluminescence Study  

E-print Network

under Joule Heating: an STM and Photoluminescence Study Jian-Ru Gong, Li-Jun Wan,* Sheng-Bin Lei, 2004 The Joule heating effect on electroluminescent efficiency is important in the degradation origin on an HOPG surface to study the OLED degradation mechanism due to thermal heating. At room temperature, BT

Gong, Jian Ru

166

The implications of self-consistent current density design guidelines comprehending electromigration and Joule heating for interconnect technology evolution  

Microsoft Academic Search

We comprehend both electromigration and Joule heating to study for the first time the self-consistent solutions for the maximum allowed interconnect peak current density jpeak Using worst-case heat losses, we show how these solutions can be used to generate adequately safe current density design guidelines. They indicate that thermal effects will dominate the ability to increase jpeak, rather than EM

William R. Hunter

1995-01-01

167

MHD Mixed Convective Peristaltic Motion of Nanofluid with Joule Heating and Thermophoresis Effects  

PubMed Central

The primary objective of present investigation is to introduce the novel aspect of thermophoresis in the mixed convective peristaltic transport of viscous nanofluid. Viscous dissipation and Joule heating are also taken into account. Problem is modeled using the lubrication approach. Resulting system of equations is solved numerically. Effects of sundry parameters on the velocity, temperature, concentration of nanoparticles and heat and mass transfer rates at the wall are studied through graphs. It is noted that the concentration of nanoparticles near the boundaries is enhanced for larger thermophoresis parameter. However reverse situation is observed for an increase in the value of Brownian motion parameter. Further, the mass transfer rate at the wall significantly decreases when Brownian motion parameter is assigned higher values. PMID:25391147

Shehzad, Sabir Ali; Abbasi, Fahad Munir; Hayat, Tasawar; Alsaadi, Fuad

2014-01-01

168

MHD Mixed Convective Peristaltic Motion of Nanofluid with Joule Heating and Thermophoresis Effects.  

PubMed

The primary objective of present investigation is to introduce the novel aspect of thermophoresis in the mixed convective peristaltic transport of viscous nanofluid. Viscous dissipation and Joule heating are also taken into account. Problem is modeled using the lubrication approach. Resulting system of equations is solved numerically. Effects of sundry parameters on the velocity, temperature, concentration of nanoparticles and heat and mass transfer rates at the wall are studied through graphs. It is noted that the concentration of nanoparticles near the boundaries is enhanced for larger thermophoresis parameter. However reverse situation is observed for an increase in the value of Brownian motion parameter. Further, the mass transfer rate at the wall significantly decreases when Brownian motion parameter is assigned higher values. PMID:25391147

Shehzad, Sabir Ali; Abbasi, Fahad Munir; Hayat, Tasawar; Alsaadi, Fuad

2014-01-01

169

Microchannel heat exchanger for two-phase Mixed Refrigerant Joule Thomson process  

NASA Astrophysics Data System (ADS)

Mixed Refrigerant Joule Thomson (MR-JT) refrigerators are widely used in various kinds of cryogenic systems these days. Printed Circuit Heat Exchanger (PCHE) is one of the promising cryogenic compact recuperators for MR-JT refrigerators due to its compactness, high NTU and robustness. However, PCHE composed with microchannel bundles can cause flow mal-distribution, and it can cause the degradation of thermal performance of the system. To mitigate the flow mal-distribution problem, the cross link (or intra-layer bypass) can be adapted to parallel microchannels. Two heat exchangers are fabricated in this study; one has straight channels, and the other one has intra-layer bypass structure between channels to enhance the flow distribution. The MR-JT refrigerators are operated with these two heat exchanger and the no-load temperatures are compared. The lower no load temperature achieved with the intra-layer bypass structured heat exchanger. The results indicate that the flow mal-distribution in the microchannel heat exchanger can be mitigated with intra-layer bypass structure, and relaxation of flow mal-distribution in the heat exchanger guarantee the MR-JT refrigerator's performance.

Baek, Seungwhan; Lee, Jisung; Lee, Cheonkyu; Jeong, Sangkwon

2014-01-01

170

On the relative importance of Joule heating and the Lorentz force in generating atmospheric gravity waves and infrasound waves in the auroral electrojets  

Microsoft Academic Search

An analysis of the relative importance of the contribution from the Lorentz force and the Joule heating rate as source for the TIDs reveals that a strong height dependence must be expected. Also it is found that for horizontal electric fields larger than about 40 mV\\/m the Joule heating rate will be most dominant above 110 km.

A. Brekke

1979-01-01

171

Current-Controlled Negative Differential Resistance due to Joule Heating in TiO2  

E-print Network

We show that Joule heating causes current-controlled negative differential resistance (CC-NDR) in TiO2 by constructing an analytical model of the voltage-current V(I) characteristic based on polaronic transport for Ohm's Law and Newton's Law of Cooling, and fitting this model to experimental data. This threshold switching is the 'soft breakdown' observed during electroforming of TiO2 and other transition-metal-oxide based memristors, as well as a precursor to 'ON' or 'SET' switching of unipolar memristors from their high to their low resistance states. The shape of the V(I) curve is a sensitive indicator of the nature of the polaronic conduction.

Alexandrov, A S; Bridle, B; Savel'ev, S E; Strukov, D B; Williams, R Stanley

2011-01-01

172

Consistent melting behavior induced by Joule heating between Ag microwire and nanowire meshes  

NASA Astrophysics Data System (ADS)

The melting behavior of an Ag microwire mesh induced by Joule heating was numerically investigated and compared with that of the corresponding Ag nanowire mesh with the same structure but different geometrical and physical properties of the wire itself. According to the relationship of melting current and melting voltage during the melting process, a similar repetitive zigzag pattern in melting behavior was discovered in both meshes. On this basis, a dimensionless parameter defined as figure of merit was proposed to characterize the current-carrying ability of the mesh. The consistent feature of figure of merit in both meshes indicates that the melting behavior of the Ag nanowire mesh can be predicted from the present results of the corresponding Ag microwire mesh with the same structure but made from a different wire (e.g., different size, different material) through simple conversion. The present findings can provide fundamental insight into the reliability analysis on the metallic nanowire mesh-based transparent conductive electrode.

Tsuchiya, Kaoru; Li, Yuan; Saka, Masumi

2014-05-01

173

Numerical analysis of the electrical failure of a metallic nanowire mesh due to Joule heating.  

PubMed

To precisely examine the electrical failure behavior of a metallic nanowire mesh induced by Joule heating (i.e., melting), a previously developed numerical method was modified with regard to the maximum temperature in the mesh and the electrical resistivity of the nanowire. A sample case of an Ag nanowire mesh under specific working conditions was analyzed with highly accurate numerical results. By monitoring the temperature in the mesh, the current required to trigger the melting of a mesh segment (i.e., the melting current) could be obtained. The melting process of a mesh equipped with a current source during actual operation was predicted on the basis of the obtained relationship between the melting current and the corresponding melting voltage in the numerical melting process. Local unstable and stable melting could be precisely identified for both the current-controlled and voltage-controlled current sources in the present example. PMID:23992528

Li, Yuan; Tsuchiya, Kaoru; Tohmyoh, Hironori; Saka, Masumi

2013-01-01

174

Current-Controlled Negative Differential Resistance due to Joule Heating in TiO2  

E-print Network

We show that Joule heating causes current-controlled negative differential resistance (CC-NDR) in TiO2 by constructing an analytical model of the voltage-current V(I) characteristic based on polaronic transport for Ohm's Law and Newton's Law of Cooling, and fitting this model to experimental data. This threshold switching is the 'soft breakdown' observed during electroforming of TiO2 and other transition-metal-oxide based memristors, as well as a precursor to 'ON' or 'SET' switching of unipolar memristors from their high to their low resistance states. The shape of the V(I) curve is a sensitive indicator of the nature of the polaronic conduction.

A. S. Alexandrov; A. M. Bratkovsky; B. Bridle; S. E. Savel'ev; D. B. Strukov; R. Stanley Williams

2011-08-15

175

MHD Free Convection Flow on Non-Isothermal Inclined Plate with Viscous Dissipation and Joule Heating Effects  

Microsoft Academic Search

The purpose of this work is to evaluate the magnetic effect on the MHD free convection along an inclined plate with variable surface temperature. The viscous dissipation and Joule heating effects are taken into account. The numerical solution is obtained by utilizing a fully implicit finite difference method and examined for the coupled effects of magnetic parameter M, inclination angle

Jin-Sheng Leu; Chien-Nan Lin

2008-01-01

176

Joule heating a palladium nanowire sensor for accelerated response and recovery to hydrogen gas.  

PubMed

The properties of a single heated palladium (Pd) nanowire for the detection of hydrogen gas (H(2)) are explored. In these experiments, a Pd nanowire, 48-98 microm in length, performs three functions in parallel: 1) Joule self-heating is used to elevate the nanowire temperature by up to 128 K, 2) the 4-contact wire resistance in the absence of H(2) is used to measure its temperature, and 3) the nanowire resistance in the presence of H(2) is correlated with its concentration, allowing it to function as a H(2) sensor. Compared with the room-temperature response of a Pd nanowire, the response of the heated nanowire to hydrogen is altered in two ways: First, the resistance change (DeltaR/R(0)) induced by H(2) exposure at any concentration is reduced by a factor of up to 30 and second, the rate of the resistance change - observed at the beginning ("response") and at the end ("recovery") of a pulse of H(2) - is increased by more than a factor of 50 at some H(2) concentrations. Heating nearly eliminates the retardation of response and recovery seen from 1-2% H(2), caused by the alpha --> beta phase transition of PdH(x), a pronounced effect for nanowires at room temperature. The activation energies associated with sensor response and recovery are measured and interpreted. PMID:20564483

Yang, Fan; Taggart, David K; Penner, Reginald M

2010-07-01

177

Elucidation on Joule heating and its consequences on the performance of organic light emitting diodes  

NASA Astrophysics Data System (ADS)

Current work presents a quantitative analysis of Joule heating by temperature measurements using infrared thermography and heat estimation of organic light emitting diodes (OLEDs) and their correlation with device life time. These temperature measurements were performed at 10, 20, 30, 40, and 50 mA/cm2 current densities and studied with operational time. The temperature rise of the device has increased from 9.8 to 16.6 °C within 168 h at an operating current density of 40 mA/cm2. This has been ascribed as due to the external contamination by water, oxygen, and dust particles as well as by internal heat generation. Encapsulation of the device avoids external degradation of OLEDs by preventing the destruction caused by these external contaminations. In this way, encapsulation has led to the decreased temperature rise of 12.4 °C within the duration of 168 h, which reflects the improved stability of the device. The temperature measured has been used to calculate the heat generated inside the device by solving the heat conduction equation using a transverse matrix approach. It has been found by these calculations that about 97%-98% of the power supplied to the device are converted into the heat for un-encapsulated device and results in rapid degradation of device with time, which in turns leads to the increase in operating voltage and decrease in luminous intensity with operational time. Proper encapsulation has reduced the heat generated inside the device by about 3%-4%, thereby, increasing the life time of the device. However, the glass encapsulation reduces the possibilities of the device cooling by heat convection to the atmosphere and prohibited the maximum utilization of encapsulation.

Tyagi, Priyanka; Indu Giri, Lalat; Tuli, Suneet; Srivastava, Ritu

2014-01-01

178

James Joule and meteors  

NASA Astrophysics Data System (ADS)

1989 was the hundredth anniversary of the death of James Prescott Joule, the Prescott being his mother's family name and the Joule, rhyming with cool, originating from the Derbyshire village of Youlgreave. Joule is rightly famous for his experimental efforts to establish the law of conservation of energy, and for the fact that J, the symbol known as the mechanical equivalent of heat, is named after him. Astronomically his "light has been hidden under a bushel". James Joule had a major influence on the physics of meteors.

Hughes, David W.

179

Transmission electron microscopy assisted in-situ joule heat dissipation study of individual InAs nanowires  

SciTech Connect

Managing heat transport at nanoscale is an important and challenging task for nanodevice applications and nanostructure engineering. Herein, through in-situ engineering nanowire (NW)-electrode contacts with electron beam induced carbon deposition in a transmission electron microscope, Joule heat dissipation along individual suspended Indium Arsenide NWs is well managed to obtain pre-designed temperature profiles along NWs. The temperature profiles are experimentally determined by the breakdown site of NWs under Joule heating and breakdown temperature measurement. A model with NW-electrode contacts being well considered is proposed to describe heat transport along a NW. By fitting temperature profiles with the model, thermal conductance at NW-electrode contacts is obtained. It is found that, the temperature profile along a specific NW is mainly governed by the relative thermal conductance at the two NW-electrode contacts, which is engineered in experiments.

Xu, T. T.; Wei, X. L., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn; Shu, J. P.; Chen, Q., E-mail: weixl@pku.edu.cn, E-mail: qingchen@pku.edu.cn [Key Laboratory for the Physics and Chemistry of Nanodevices and Department of Electronics, Peking University, Beijing 100871 (China)

2013-11-04

180

Analysis of magnetohydrodynamic mixed convection and joule heating in lid-driven cavity having a square block  

Microsoft Academic Search

A numerical analysis is conducted to understand the effect of magnetic field and joule heating on the flow and thermal fields in a lid-driven cavity with a centered heat-conducting horizontal square block. The two sidewalls are maintained at uniform but different temperatures Th and Tc (Th?>?Tc), while the horizontal top and bottom walls are adiabatic. The left vertical wall moves

Mohammad Arif Hasan Mamun; Rahman Saidur

2011-01-01

181

Novel application of Joule heating to maintain biocompatible temperatures in a fully integrated electromagnetic cell sorting system  

Microsoft Academic Search

Manipulation of magnetically labeled cells in a microfluidic channel is becoming a very important technique in the field of biomedical science. A microfabricated electromagnet produces a large magnetic field gradient in a cell sorting system. The microfabricated electromagnet generates Joule heating so it causes unnecessary heat-up in the device, which has been problematic for the development of a Lab-On-a-Chip (LOC).

Suk-Heung Song; Bong-Seop Kwak; Jae-Sung Park; Woochul Kim; Hyo-IL Jung

2009-01-01

182

Influence of Joule heating on magnetostriction and giant magnetoimpedance effect in a glass covered CoFeSiB microwire  

Microsoft Academic Search

The influence of annealing parameters (time ta, current Ia, and applied stress sigmaa) on magnetic properties of Joule heated amorphous Co68.15Fe4.35Si12.5B15 glass covered microwire (13 mum) was investigated. Annealing under applied stress induces additional anisotropy which is proportional to sigmaa and can be removed by subsequent heating without stress. The magnetoimpedance, measured on the sample with the lowest anisotropy field

L. Kraus; M. Knobel; S. N. Kane; H. Chiriac

1999-01-01

183

Polar thermospheric Joule heating, and redistribution of recombination energy in the upper mesosphere  

NASA Technical Reports Server (NTRS)

Kellogg (1961), suggested that transport of atomic oxygen from the summer into the winter hemisphere and subsequent release of energy by three body recombination, O+O+N2 yields O2+N2+E, may contribute significantly to the so-called mesopause temperature anomaly. Earlier model calculations have shown that Kellogg's mechanism produces about a 10-percent increase in the temperature from summer to winter at 90 km. This process, however, is partly compensated by differential heating from absorption of UV radiation associated with dissociation of O2. In the auroral region of the thermosphere, there is a steady energy dissipation by Joule heating causing a redistribution and depletion of atomic oxygen due to wind-induced diffusion. With the removal of O, latent chemical energy normally released by three body recombination is also removed, and the result is that the temperature decreases by almost 2 percent near 90 km. Through dynamic feedback, this process reduces the depletion of atomic oxygen by about 25 percent and the temperature perturbation in the exosphere from 10 to 7 percent at polar latitudes. Under the influence of the internal dynamo interaction, the prevailing zonal circulation in the upper thermosphere changes direction when the redistribution of recombination energy is considered.

Mayr, H. G.; Harris, I.; Dube, M.

1990-01-01

184

Effect of concurrent joule heat and charge trapping on RESET for NbAlO fabricated by atomic layer deposition.  

PubMed

The RESET process of NbAlO-based resistive switching memory devices fabricated by atomic layer deposition is investigated at low temperatures from 80 to 200 K. We observed that the conduction mechanism of high resistance state changed from hopping conduction to Frenkel-Poole conduction with elevated temperature. It is found that the conductive filament rupture in RRAM RESET process can be attributed not only to the Joule heat generated by internal current flow through a filament but also to the charge trap/detrapping effect. The RESET current decreases upon heating. Meanwhile, the energy consumption also decreases exponentially. This phenomenon indicates the temperature-related charge trap/detrapping process which contributes to the RESET besides direct Joule heat. PMID:23421401

Zhou, Peng; Ye, Li; Sun, Qing Qing; Wang, Peng Fei; Jiang, An Quan; Ding, Shi Jin; Zhang, David Wei

2013-01-01

185

Joule-Heated Molten Regolith Electrolysis Reactor Concepts for Oxygen and Metals Production on the Moon and Mars  

NASA Technical Reports Server (NTRS)

The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca. 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a Joule-heated (sometimes called 'self-heating') reactor in which the electrolytic currents generate enough Joule heat to create a molten bath. Solutions obtained by multiphysics modeling allow the identification of the critical dimensions of concept reactors.

Sibille, Laurent; Dominguez, Jesus A.

2012-01-01

186

Effect of concurrent joule heat and charge trapping on RESET for NbAlO fabricated by atomic layer deposition  

PubMed Central

The RESET process of NbAlO-based resistive switching memory devices fabricated by atomic layer deposition is investigated at low temperatures from 80 to 200 K. We observed that the conduction mechanism of high resistance state changed from hopping conduction to Frenkel-Poole conduction with elevated temperature. It is found that the conductive filament rupture in RRAM RESET process can be attributed not only to the Joule heat generated by internal current flow through a filament but also to the charge trap/detrapping effect. The RESET current decreases upon heating. Meanwhile, the energy consumption also decreases exponentially. This phenomenon indicates the temperature-related charge trap/detrapping process which contributes to the RESET besides direct Joule heat. PMID:23421401

2013-01-01

187

Giant magnetoimpedance effect in stress-joule-heated Co-based amorphous ribbons  

NASA Astrophysics Data System (ADS)

Co-based Co63Fe4B22.4Si5.6Nb5 amorphous ribbons with a width of 150 ?m and a thickness of 50 ?m were prepared by single-roller melt-spinning process. The giant magneto-impedance (GMI) effect of the stress-joule-heated ribbons under applied tensile stress ranging from 37 to 148 MPa was investigated. Experimental results show that the spectra of GMI ratio vs. external direct current (dc) field ( H ex) of the samples changes dramatically with annealing tension ( ?) and driving frequency. The single-peak (SP) GMI curve with maximum GMI ratio of 260% and magnetic field sensitivity of 52%/Oe was obtained in the sample applied tensile stress of 74 MPa at frequency of 3.6 MHz. A three-peak behaviour appeared in the samples under ? of 111 and 148 MPa. The uncommon three-peak behaviour was attributed to several factors, which effectively originated from the balance between domain-wall movement and magnetization rotation.

Chen, ShuangQin; Man, QiKui; Dun, ChaoChao; Shen, BaoLong

2012-12-01

188

Joule-heated glass-furnace system for the incineration of low-level radioactive wastes  

SciTech Connect

For the past 1-1/2 years, Mound has been preparing and evaluating a commercially available joule-heated glass furnace unit, coupled with a wet scrubbing system. The purpose of the glass furnace evaluation is to advance and document incinerator technology for such combustibles as solids, resins, and sludges, and to develop a stable waste form for subsequent disposal. Four (4) waste nonradioactive types were selected to determine the combustion efficiency of the furnace unit: (1) dry solid waste composed of paper, plastics, rubber, and cloth, (2) ion exchange resin of both the anionic and cationic type, (3) filter sludge composed of diatomaceous earth, organic cellulosic filter aid, and powdered ion exchange resin, and (4) cartridge filters having glass and plastic filter surfaces and nonmetallic cores. When completed, the combustion efficiency experiments for the proposed nonradioactive waste-types revealed the ability of the furnace to easily incinerate waste at feedrates of up to 150 lb/hr. During the course of the experiments, combustibles in the offgas remained consistently low, suggesting excellent combustion efficiency. Furthermore, ash produced by the combustion process was effectively incorporated into the melt by convective currents in the glass. Future work on the glass furnace incinerator will include spiking the waste to determine radioisotope behavior in the furnace.

Armstrong, K.M.; Klingler, L.M.; Doty, J.W.; Kramer, D.P.

1982-01-01

189

Consistent melting behavior induced by Joule heating between Ag microwire and nanowire meshes.  

PubMed

The melting behavior of an Ag microwire mesh induced by Joule heating was numerically investigated and compared with that of the corresponding Ag nanowire mesh with the same structure but different geometrical and physical properties of the wire itself. According to the relationship of melting current and melting voltage during the melting process, a similar repetitive zigzag pattern in melting behavior was discovered in both meshes. On this basis, a dimensionless parameter defined as figure of merit was proposed to characterize the current-carrying ability of the mesh. The consistent feature of figure of merit in both meshes indicates that the melting behavior of the Ag nanowire mesh can be predicted from the present results of the corresponding Ag microwire mesh with the same structure but made from a different wire (e.g., different size, different material) through simple conversion. The present findings can provide fundamental insight into the reliability analysis on the metallic nanowire mesh-based transparent conductive electrode. PMID:24910578

Tsuchiya, Kaoru; Li, Yuan; Saka, Masumi

2014-01-01

190

Joule heating rate need not equal I2R, where R is the Ohmic resistance: The case of voltaic cells  

NASA Astrophysics Data System (ADS)

The electrolyte within a charging or discharging voltaic cell, carrying current I, has time-dependent carrier densities. Therefore the energy conservation argument that equates the total rate of Joule heating P to the rate of decrease of electrical energy is inappropriate because it neglects changes in chemical energy. Explicit study of two systems (the lead-acid cell and the Zn-Cu cell) shows that the Joule heating resistance RJ=P/I2 differs from the Ohmic resistance R=?V/I (?V is the voltage drop across the electrolyte). R/RJ can be greater than or less than unity. RJ involves only the current-carrying ions, whereas R involves all of the ions.

Saslow, Wayne M.

1999-02-01

191

Transformation temperatures and shape memory characteristics of a Ti45Ni5Cu(at %) alloy annealed by Joule heating  

Microsoft Academic Search

A temperature gradient of 75-188 K was developed in a Ti-45Ni-5Cu(at %) alloy wire with 30 mm length by Joule heating, depending on electrical power. The shape change rate increased from 0.022 to 0.045% K-1 on increasing the electrical power from 4.8 to 6.2 W. The change in the stress required for the B2-B19' transformation increased from 60 to 103

Seok-Won Kang; Gyu-Bong Cho; Seung-Yong Yang; Yinong Liu; Hong Yang; Shuichi Miyazaki; Tae-Hyun Nam

2010-01-01

192

Evaluation of temperature rise due to joule heating and preliminary investigation of its effect on electromigration reliability  

Microsoft Academic Search

A demand to increase current density of ULSI interconnections with shrinkage of feature sizes inevitably brings about temperature rise due to Joule heating. We studied how temperature distribution changes with an increase in the current density and further investigated its effect on electromigration-induced failures. We evaluated a temperature rise in a single level Al-alloy interconnection by the use of IR-CCD

S. Shingubara; S. Miyazaki; H. Sakaue; T. Takahagi

2002-01-01

193

Effects of high-latitude ionospheric electric field variability on global thermospheric Joule heating and mechanical energy transfer rate  

Microsoft Academic Search

Effects of high-latitude ionospheric electric field variability on the Joule heating and mechanical energy transfer rate are investigated by incorporating realistic spatial and temporal characteristics of electric field variability derived from observations into the forcing of a thermosphere ionosphere electrodynamic general circulation model. First, the characteristics of subgrid-scale variability are examined from a spectral analysis of Dynamic Explorer-2 (DE-2) plasma

Tomoko Matsuo

2008-01-01

194

Modified data analysis for thermal conductivity measurements of polycrystalline silicon microbridges using a steady state Joule heating technique  

NASA Astrophysics Data System (ADS)

Accurate knowledge of thermophysical properties is needed to predict and optimize the thermal performance of microsystems. Thermal conductivity is experimentally determined by measuring quantities such as voltage or temperature and then inferring a thermal conductivity from a thermal model. Thermal models used for data analysis contain inherent assumptions, and the resultant thermal conductivity value is sensitive to how well the actual experimental conditions match the model assumptions. In this paper, a modified data analysis procedure for the steady state Joule heating technique is presented that accounts for bond pad effects including thermal resistance, electrical resistance, and Joule heating. This new data analysis method is used to determine the thermal conductivity of polycrystalline silicon (polysilicon) microbridges fabricated using the Sandia National Laboratories SUMMiT V™ micromachining process over the temperature range of 77-350 K, with the value at 300 K being 71.7 ± 1.5 W/(m K). It is shown that making measurements on beams of multiple lengths is useful, if not essential, for inferring the correct thermal conductivity from steady state Joule heating measurements.

Sayer, Robert A.; Piekos, Edward S.; Phinney, Leslie M.

2012-12-01

195

Effect of Joule heating on electro-osmotic flow in a closedend micro-channel with isothermal and convective boundary conditions  

Microsoft Academic Search

The effect of Joule heating on the steady state electro-osmotic flow in a closed-end micro-channel is studied through numerical\\u000a simulation with the finite volume method. The velocity field and the temperature field are described by a rigorous mathematical\\u000a model. Thermophysical properties including viscosity and thermal conductivity are considered to be temperature-dependent.\\u000a The simulations show that the presence of Joule heating

Liang Zhao; Linhua Liu

2009-01-01

196

A self-heated silicon nanowire array: selective surface modification with catalytic nanoparticles by nanoscale Joule heating and its gas sensing applications  

NASA Astrophysics Data System (ADS)

We demonstrated novel methods for selective surface modification of silicon nanowire (SiNW) devices with catalytic metal nanoparticles by nanoscale Joule heating and local chemical reaction. The Joule heating of a SiNW generated a localized heat along the SiNW and produced endothermic reactions such as hydrothermal synthesis of nanoparticles or thermal decomposition of polymer thin films. In the first method, palladium (Pd) nanoparticles could be selectively synthesized and directly coated on a SiNW by the reduction of the Pd precursor via Joule heating of the SiNW. In the second method, a sequential process composed of thermal decomposition of a polymer, evaporation of a Pd thin film, and a lift-off process was utilized. The selective decoration of Pd nanoparticles on SiNW was successfully accomplished by using both methods. Finally, we demonstrated the applications of SiNWs decorated with Pd nanoparticles as hydrogen detectors. We also investigated the effect of self-heating of the SiNW sensor on its sensing performance.We demonstrated novel methods for selective surface modification of silicon nanowire (SiNW) devices with catalytic metal nanoparticles by nanoscale Joule heating and local chemical reaction. The Joule heating of a SiNW generated a localized heat along the SiNW and produced endothermic reactions such as hydrothermal synthesis of nanoparticles or thermal decomposition of polymer thin films. In the first method, palladium (Pd) nanoparticles could be selectively synthesized and directly coated on a SiNW by the reduction of the Pd precursor via Joule heating of the SiNW. In the second method, a sequential process composed of thermal decomposition of a polymer, evaporation of a Pd thin film, and a lift-off process was utilized. The selective decoration of Pd nanoparticles on SiNW was successfully accomplished by using both methods. Finally, we demonstrated the applications of SiNWs decorated with Pd nanoparticles as hydrogen detectors. We also investigated the effect of self-heating of the SiNW sensor on its sensing performance. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01640d

Yun, Jeonghoon; Jin, Chun Yan; Ahn, Jae-Hyuk; Jeon, Seokwoo; Park, Inkyu

2013-07-01

197

Auroral ionosphere Joule heating as a reason of the upper thermosphere overheating in the Jupiter and Saturn systems  

NASA Astrophysics Data System (ADS)

All giant planets in the Solar System and particularly Saturn and Jupiter are known to have an upper neutral atmosphere far hotter than it is expected from solar extreme ultraviolet heating alone. While the measured exospheric temperatures on Saturn and Jupiter are close to 500 K and to 1100 K - 2000 K, respectively, the solar heating alone can provide an exospheric temperature only about 200 K. Two main energy deposition mechanisms are discussed in the literature to resolve this contradictions: (1) the gravitation wave dissipation in the upper atmosphere, and (2) the auroral thermosphere Joule heating by the Pedersen ionospheric currents. The ionospheric currents are associated with the field-aligned currents generated due to the magnetosphere-ionosphere slipping. Here we focus on the second mechanism. To improve the accuracy of the numerical estimations we derived the analytic formulas, which describe the dependence of the auroral energy flux on the planetary magnetic field strength, as well as on the solar wind plasma ram pressure, and on the breaking of magnetospheric plasma corotation. The last effect is essential for Jupiter, where the main oval is driven internally at Alvenic radius. We pay attention to the general physical phenomena, which may be only slightly influenced/modified by the specific atmospheric composition and photochemical ionospheric reactions. One of the most important energy inputs to the polar upper atmosphere is Joule heating by the ionospheric Pedersen currents. We estimate it to be ~3.0 TW for Saturn and about 1000 times more (3500 TW) for Jupiter. That represents a significant energy input to Saturn’s and Jupiter’s thermospheres. It is more than an order of magnitude larger as compared to the globally averaged solar input. Therefore, Joule heating may be reasonably appealed for the explanation of the observed high thermosphere temperatures by Saturn (~400-600 K) and Jupiter (1200 K).

Alexeev, Igor; Belenkaya, Elena; Khodachenko, Maxim; Grigoryan, Maria

198

Unsteady magnetohydrodynamic Hartmann-Couette flow and heat transfer in a Darcian channel with Hall current, ionslip, viscous and Joule heating effects: Network numerical solutions  

Microsoft Academic Search

A theoretical study of unsteady magnetohydrodynamic viscous Hartmann-Couette laminar flow and heat transfer in a Darcian porous medium intercalated between parallel plates, under a constant pressure gradient is presented. Viscous dissipation, Joule heating, Hall current and ionslip current effects are included as is lateral mass flux at both plates. The dimensionless conservation equations for the primary (x*-direction), secondary (z*-direction) momentum

O. Anwar Bég; Joaquín Zueco; H. S. Takhar

2009-01-01

199

Unsteady magnetohydrodynamic Hartmann–Couette flow and heat transfer in a Darcian channel with Hall current, ionslip, viscous and Joule heating effects: Network numerical solutions  

Microsoft Academic Search

A theoretical study of unsteady magnetohydrodynamic viscous Hartmann–Couette laminar flow and heat transfer in a Darcian porous medium intercalated between parallel plates, under a constant pressure gradient is presented. Viscous dissipation, Joule heating, Hall current and ionslip current effects are included as is lateral mass flux at both plates. The dimensionless conservation equations for the primary (x?-direction), secondary (z?-direction) momentum

O. Anwar Bég; Joaquín Zueco; H. S. Takhar

2009-01-01

200

Transformation temperatures and shape memory characteristics of a Ti-45Ni-5Cu(at %) alloy annealed by Joule heating  

NASA Astrophysics Data System (ADS)

A temperature gradient of 75-188 K was developed in a Ti-45Ni-5Cu(at %) alloy wire with 30 mm length by Joule heating, depending on electrical power. The shape change rate increased from 0.022 to 0.045% K-1 on increasing the electrical power from 4.8 to 6.2 W. The change in the stress required for the B2-B19' transformation increased from 60 to 103 MPa on increasing the electrical power from 4.8 to 10.1 W.

Kang, Seok-Won; Cho, Gyu-Bong; Yang, Seung-Yong; Liu, Yinong; Yang, Hong; Miyazaki, Shuichi; Nam, Tae-Hyun

2010-05-01

201

The Effect of Multipole-Enhanced Diffusion on the Joule Heating of a Cold Non-Neutral Plasma  

E-print Network

One proposed technique for trapping anti-atoms is to superimpose a Ioffe-Pritchard style magnetic-minimum neutral trap on a standard Penning trap used to trap the charged atomic constituents. Adding a magnetic multipole field in this way removes the azimuthal symmetry of the ideal Penning trap and introduces a new avenue for radial diffusion. Enhanced diffusion will lead to increased Joule heating of a non-neutral plasma, potentially adversely affecting the formation rate of anti-atoms and increasing the required trap depth. We present a model of this effect, along with an approach to minimizing it, with comparison to measurements from an intended anti-atom trap.

Chapman, Steven Francis

202

Numerical study on the conjugate effect of joule heating and magnato-hydrodynamics mixed convection in an obstructed lid-driven square cavity  

Microsoft Academic Search

Conjugate effect of joule heating and magnetic force, acting normal to the left vertical wall of an obstructed lid-driven cavity saturated with an electrically conducting fluid have been investigated numerically. The cavity is heated from the right vertical wall isothermally. Temperature of the left vertical wall, which has constant flow speed, is lower than that of the right vertical wall.

M. M. Rahman; M. A. Alim; M. M. A. Sarker

2010-01-01

203

Non-linear effects and Joule heating in IV curves in manganites  

Microsoft Academic Search

We study the influence of the Joule effect on the non-linear behavior of the\\u000atransport I-V curves in polycrystalline samples of the manganite Pr0.8Ca0.2MnO3\\u000aby using the crystalline unit cell parameters as an internal thermometer in\\u000aX-ray and neutron diffraction. We develop a simple analytical model to estimate\\u000athe temperature profile in the samples. Under the actual experimental\\u000aconditions we

Silvana Mercone; Raymond Frésard; Vincent Caignaert; Christine Martin; Damien Saurel; Charles Simon; Gilles Andre; Philippe Monod; Francois Fauth

2005-01-01

204

Measurement and simulation of Joule heating during treatment of B-16 melanoma tumors in mice with nanosecond pulsed electric fields.  

PubMed

Experimental evidence shows that nanosecond pulsed electric fields (nsPEF) trigger apoptosis in skin tumors. We have postulated that the energy delivered by nsPEF is insufficient to impart significant heating to the treated tissue. Here we use both direct measurements and theoretical modeling of the Joule heating in order to validate this assumption. For the temperature measurement, thermo-sensitive liquid crystals (TLC) were used to determine the surface temperature while a micro-thermocouple (made from 30 ?m wires) was used for measuring the temperature inside the tissue. The calculation of the temperature distribution used an asymptotic approach with the repeated calculation of the electric field, Joule heating and heat transfer, and the subsequent readjustment of the electrical tissue conductivity. This yields a temperature distribution both in space and time. It can be shown that for the measured increase in temperature an unexpectedly high electrical conductivity of the tissue would be required, which was indeed found by using voltage and current monitoring during the experiment. Using impedance measurements within t(after)=50 ?s after the pulse revealed a fast decline of the high conductivity state when the electric field ceases. The experimentally measured high conductance of a skin fold (mouse) between plate electrodes was about 5 times higher than those of the maximally expected conductance due to fully electroporated membrane structures (G(max)/G(electroporated))?5. Fully electroporated membrane structure assumes that 100% of the membranes are conductive which is estimated from an impedance measurement at 10 MHz where membranes are capacitively shorted. Since the temperature rise in B-16 mouse melanoma tumors due to equally spaced (?t=2 s) 300 ns-pulses with E=40 kV/cm usually does not exceed ??=3 K at all parts of the skin fold between the electrodes, a hyperthermic effect on the tissue can be excluded. PMID:24680133

Pliquett, Uwe; Nuccitelli, Richard

2014-12-01

205

Nonlinear effects and Joule heating in I-V curves in manganites  

NASA Astrophysics Data System (ADS)

We study the influence of the Joule effect on the nonlinear behavior of the transport I-V curves in polycrystalline samples of the manganite Pr0.8Ca0.2MnO3 by using the crystalline unit-cell parameters as an internal thermometer in x-ray and neutron diffractions. We develop a simple analytical model to estimate the temperature profile in the samples. Under the actual experimental conditions we show that the internal temperature gradient or the difference between the temperature of the sample and that of the thermal bath is at the origin of the nonlinearity observed in the I-V curves. Consequences on other compounds with colossal magnetoresistance are also discussed.

Mercone, Silvana; Frésard, Raymond; Caignaert, Vincent; Martin, Christine; Saurel, Damien; Simon, Charles; André, Gilles; Monod, Philippe; Fauth, François

2005-07-01

206

The Joule heat production rate and the particle energy injection rate as a function of the geomagnetic indices AE and AL  

Microsoft Academic Search

Magnetic records from 71 stations were employed to determine the distribution of electric fields and currents in the polar ionosphere for March 17, 18, and 19, 1978. Hourly distribution maps of the Joule heat production rate, the particle energy injection rate, and their sum over the entire polar region on the three days were calculated. For constructing the hourly distribution

B.-H. Ahn; S.-I. Akasofu; Y. Kamide

1983-01-01

207

Estimate of the Relative Importance of Joule Heating and the Lorentz Force in Generating Atmospheric Gravity Waves from the Auroral Electrojet  

Microsoft Academic Search

The general problem of generation of atmospheric gravity waves (AGW's) by the auroral electrojet and the relative roles of Joule heat- ing and the Lorentz force have been treated in theoretical developments by Chimonas and Hines (1970), Testud (1973), and Francis (1974, 1975). In their paper, Chimonas and Hines derive an expression which describes the relative contribution of the Lorentz

Robert D. Hunsucker

1977-01-01

208

Experimental evaluation of an adaptive Joule-Thomson cooling system including silicon-microfabricated heat exchanger and microvalve components  

PubMed Central

This article reports the evaluation of a Joule–Thomson (JT) cooling system that combines two custom micromachined components—a Si/glass-stack recuperative heat exchanger and a piezoelectrically actuated expansion microvalve. With the microvalve controlling the flow rate, this system can modulate cooling to accommodate varying refrigeration loads. The perforated plate Si/glass heat exchanger is fabricated with a stack of alternating silicon plates and Pyrex glass spacers. The microvalve utilizes a lead zirconate titanate actuator to push a Si micromachined valve seat against a glass plate, thus modulating the flow passing through the gap between the valve seat and the glass plate. The fabricated heat exchanger has a footprint of 1 × 1 cm2 and a length of 35 mm. The size of the micromachined piezoelectrically actuated valve is about 1 × 1 × 1 cm3. In JT cooling tests, the temperature of the system was successfully controlled by adjusting the input voltage of the microvalve. When the valve was fully opened (at an input voltage of ?30 V), the system cooled down to a temperature as low as 254.5 K at 430 kPa pressure difference between inlet and outlet at steady state and 234 K at 710 kPa in a transient state. The system provided cooling powers of 75 mW at 255 K and 150 mW at 258 K. Parasitic heat loads at 255 K are estimated at approximately 700 mW. PMID:21552354

Zhu, Weibin; Park, Jong M.; White, Michael J.; Nellis, Gregory F.; Gianchandani, Yogesh B.

2011-01-01

209

Considerable different frequency dependence of dynamic tensile modulus between self-heating (Joule heat) and external heating for polymer--nickel-coated carbon fiber composites.  

PubMed

Dynamic tensile moduli of polyethylene--nickel-coated carbon fiber (NiCF) composites with 10 and 4 vol % NiCF contents under electrical field were measured by a homemade instrument in the frequency range of 100--0.01 Hz. The drastic descent of the storage modulus of the composite with 10 vol % was verified in lower frequency range with elevating surface temperature (T(s)) by self-heating (Joule heat). The composite was cut when T(s) was beyond 108 °C. On the other hand, the measurement of the composite with 4 vol % beyond 88 °C was impossible, since T(s) did not elevate because of the disruption of current networks. Incidentally, the dynamic tensile moduli by external heating could be measured up to 130 and 115 °C for 10 and 4 vol %, respectively, but the two composites could be elongated beyond the above temperatures. Such different properties were analyzed in terms of crystal dispersions, electrical treeing, and thermal fluctuation-induced tunneling effect. PMID:24893179

Zhang, Rong; Bin, Yuezhen; Dong, Enyuan; Matsuo, Masaru

2014-06-26

210

MHD Free Convection Flow on Non-Isothermal Inclined Plate with Viscous Dissipation and Joule Heating Effects  

NASA Astrophysics Data System (ADS)

The purpose of this work is to evaluate the magnetic effect on the MHD free convection along an inclined plate with variable surface temperature. The viscous dissipation and Joule heating effects are taken into account. The numerical solution is obtained by utilizing a fully implicit finite difference method and examined for the coupled effects of magnetic parameter M, inclination angle ?, exponent values of power-law relation n, and Prandtl number Pr on the local and average flow and heat transfer characteristics. The results show that the presence as well as the increase in the magnetic field decreases velocity and heat transfer performance. The influences of M are more significant for smaller n and Pr. For Pr=0.01 and n=-1/3, the average Nusselt number Nuav(M=4) is decreased 83.3% relative to that of Nuav(M=0). In addition, the velocity, temperature gradient, and Nusselt numbers are increased with the increase of ?, Pr and n.

Leu, Jin-Sheng; Lin, Chien-Nan

211

A procedure for the calculation of the natural gas molar heat capacity, the isentropic exponent, and the Joule–Thomson coefficient  

Microsoft Academic Search

A numerical procedure for the computation of a natural gas molar heat capacity, the isentropic exponent, and the Joule–Thomson coefficient has been derived using fundamental thermodynamic equations, DIPPR AIChE generic ideal heat capacity equations, and AGA-8 extended virial-type equations of state. The procedure is implemented using the Object-Oriented Programming (OOP) approach. The results calculated are compared with the corresponding measurement

Ivan Mari?

2007-01-01

212

The Joule-Thomson effect on the thermoelectric LUISA CONSIGLIERI  

E-print Network

value elliptic problem which describes the electrical heating of a solid conductor and the Joule and irreversible effects are impossible to be separated. The irreversible processes are the Joule heating due gradient. In the works [5, 14] the Joule-Thomson effect only appears as a heat source in the heat

Lisbon, University of

213

Off-gas characteristics of defense waste vitrification using liquid-fed Joule-heated ceramic melters  

SciTech Connect

Off-gas and effluent characterization studies have been established as part of a PNL Liquid-Fed Ceramic Melter development program supporting the Savannah River Laboratory Defense Waste Processing Facility (SRL-DWPF). The objectives of these studies were to characterize the gaseous and airborne emission properties of liquid-fed joule-heated melters as a function of melter operational parameters and feed composition. All areas of off-gas interest and concern including effluent characterization, emission control, flow rate behavior and corrosion effects have been studied using alkaline and formic-acid based feed compositions. In addition, the behavioral patterns of gaseous emissions, the characteristics of melter-generated aerosols and the nature and magnitude of melter effluent losses have been established under a variety of feeding conditions with and without the use of auxiliary plenum heaters. The results of these studies have shown that particulate emissions are responsible for most radiologically important melter effluent losses. Melter-generated gases have been found to be potentially flammable as well as corrosive. Hydrogen and carbon monoxide present the greatest flammability hazard of the combustibles produced. Melter emissions of acidic volatile compounds of sulfur and the halogens have been responsible for extensive corrosion observed in melter plenums and in associated off-gas lines and processing equipment. The use of auxiliary plenum heating has had little effect upon melter off-gas characteristics other than reducing the concentrations of combustibles.

Goles, R.W.; Sevigny, G.J.

1983-09-01

214

Bipolar resistance switching in high-performance Cu/ZnO:Mn/Pt nonvolatile memories: active region and influence of Joule heating  

NASA Astrophysics Data System (ADS)

Manganese-doped ZnO dielectric films sandwiched between Cu and Pt electrodes were prepared and investigated for nonvolatile resistive memory applications. These structures exhibit promising bipolar resistive switching (RS) behavior with a large ON/OFF ratio (~103), suitable threshold voltages (1.4 and -0.7 V for SET and RESET, respectively), long retention (>104 s at 85 °C) and low write current (10 ?A). A study on the ZnO:Mn thickness dependence of threshold voltages reveals that RS should be an interfacial effect rather than bulk behavior. By elevating current compliance during the SET process, an anomalous transition from bistable memory switching to monostable threshold switching was observed, which is attributed to the instability of conductive filaments induced by Joule heating effects. Apart from this, fast voltage sweep cycles without efficient heat dissipation were also found to accelerate the hard dielectric breakdown of the device, reflecting the impact of accumulative Joule heating. These results reveal the possible influences of Joule heating effects on bipolar resistance switching and thus the necessity of avoiding them in future high-density memory applications. Conceivable solutions are considered to be reducing the operating currents and improving the heat dissipation of memory devices based on our experiments.

Chao Yang, Yu; Pan, Feng; Zeng, Fei

2010-02-01

215

Joule heating-induced coexisted spin Seebeck effect and spin Hall magnetoresistance in the platinum/Y3Fe5O12 structure  

NASA Astrophysics Data System (ADS)

Spin Seebeck effect (SSE) and spin Hall magnetoresistance (SMR) are observed simultaneously in the Pt/Y3Fe5O12 hybrid structure when thermal gradient is produced by Joule heating. According to their dependences on applied current, these two effects can be separated. Their dependence on heating power and magnetic field is systematically studied. With the increase of heating power, the SSE enhances linearly, whereas the SMR decreases slowly. The origin of the spin currents is further analyzed. The heating power dependences of the spin currents associated with the SSE and the SMR are found to be different.

Wang, W. X.; Wang, S. H.; Zou, L. K.; Cai, J. W.; Sun, Z. G.; Sun, J. R.

2014-11-01

216

Performances of the mixed-gases Joule-Thomson refrigeration cycles for cooling fixed-temperature heat loads  

NASA Astrophysics Data System (ADS)

Numerous mixed-gases refrigeration cycle configurations based on Joule-Thomson effects were developed in the past several decades. In this paper, comprehensive thermodynamic analyses were made on two typical cycle configurations to learn their performance for cooling fixed-temperature heat loads. One is the single-stage cycle without phase separators; the other is the auto-cascade refrigeration cycle which has at least one phase separator. An exergy model was developed to analyze the thermodynamic performance of those refrigeration cycles. Comprehensive comparisons were made on the performance of the recuperative throttling cycles using multicomponent mixture as refrigerant, including extensive simulations and optimizations of mixtures and cycle configurations. The results show that the auto-cascade cycle can improve thermodynamic performance in the case of using mixtures with increased fraction of high-boiling components, however, degrade the performance when using mixtures with increased fraction of low-boiling components. The results also show that the mixed refrigerant is the most important designing parameter in the design of such mixed-gases refrigeration system. Different cycle configuration has different optimal mixture composition. When using optimal mixtures, both cycles (separation and non-separation) can provide approximately equal performance.

Gong, M. Q.; Wu, J. F.; Luo, E. G.

2004-12-01

217

Existence of weak solutions for the nonstationary problem of the Joule heating of a conductor  

Microsoft Academic Search

Summary An initial-boundary value problem for a system of two nonlinear partial differential equations is studied using the Faedo-Galerkin method. The problem describes the electric heating of a conducting body. The main result is a theorem of existence of weak solutions for an arbitrarily large interval of time.

Giovanni Cimatti

1992-01-01

218

A finite element model for the time-dependent Joule heating problem  

Microsoft Academic Search

. We study a spatially semidiscrete and a completely discrete finite elementmodel for a nonlinear system consisting of an elliptic and a parabolic partial differentialequation describing the electric heating of a conducting body. We prove error boundsof optimal order under minimal regularity assumptions when the number of spatialvariables d 3. We establish the existence of solutions with the required regularityover

Charles M. Elliott; Stig Larsson

1995-01-01

219

DC characteristics of patterned YBa2Cu3O7-x superconducting thin-film bolometers: artifacts related to Joule heating, ambient pressure, and microstructure  

Microsoft Academic Search

Joule heating due to the bias current and resistance of the material in patterned YBa2Cu3O7-x, superconducting films on 250-500-?m-thick MgO, LaAlO3, and SrTiO3 crystalline substrates, results in a number of effects: (1) a temperature rise in the film with respect to the measured temperature at the bottom of the substrate; (2) a possible thermal runaway, which may be local or

Mehdi Fardmanesh; Kevin Scoles; Allen Rothwarf

1998-01-01

220

Combined effect of viscous dissipation and Joule heating on MHD forced convection over a non-isothermal horizontal cylinder embedded in a fluid saturated porous medium  

Microsoft Academic Search

The effects of both first- and second-order resistance, due to the solid matrix of non-Darcy porous medium, Joule heating and viscous dissipation on forced convection flow from a horizontal circular cylinder under the action of a transverse magnetic field, has been studied. The case of variable wall temperature conditions is considered. The second-level local non-similarity method is used to convert

M. F. El-Amin

2003-01-01

221

Effect of current crowding and Joule heating on electromigration-induced failure in flip chip composite solder joints tested at room temperature  

SciTech Connect

The electromigration of flip chip solder joints consisting of 97Pb-3Sn and 37Pb-63Sn composite solders was studied under high current densities at room temperature. The mean time to failure and failure modes were found to be strongly dependent on the change in current density. The composite solder joints did not fail after 1 month stressed at 4.07x10{sup 4} A/cm{sup 2}, but failed after just 10 h of current stressing at 4.58x10{sup 4} A/cm{sup 2}. At a slightly higher current stressing of 5.00x10{sup 4} A/cm{sup 2}, the composite solder joints failed after only 0.6 h due to melting. Precipitation and growth of Cu{sub 6}Sn{sub 5} at the cathode caused the Cu under bump metallurgy to be quickly consumed and resulted in void formation at the contact area. The void reduced the contact area and displaced the electrical path, affecting the current crowding and Joule heating inside the solder bump. Significant Joule heating inside solder bumps can cause melting of the solder and quick failure. The effect of void propagation on current crowding and Joule heating was confirmed by simulation.

Nah, J.W.; Suh, J.O.; Tu, K.N. [Department of Materials Science and Engineering, University of California at Los Angeles (UCLA), Los Angeles, California 90095-1595 (United States)

2005-07-01

222

Effect of Joule heating and thermal radiation in flow of third grade fluid over radiative surface.  

PubMed

This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number. PMID:24454694

Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

2014-01-01

223

Effect of Joule Heating and Thermal Radiation in Flow of Third Grade Fluid over Radiative Surface  

PubMed Central

This article addresses the boundary layer flow and heat transfer in third grade fluid over an unsteady permeable stretching sheet. The transverse magnetic and electric fields in the momentum equations are considered. Thermal boundary layer equation includes both viscous and Ohmic dissipations. The related nonlinear partial differential system is reduced first into ordinary differential system and then solved for the series solutions. The dependence of velocity and temperature profiles on the various parameters are shown and discussed by sketching graphs. Expressions of skin friction coefficient and local Nusselt number are calculated and analyzed. Numerical values of skin friction coefficient and Nusselt number are tabulated and examined. It is observed that both velocity and temperature increases in presence of electric field. Further the temperature is increased due to the radiation parameter. Thermal boundary layer thickness increases by increasing Eckert number. PMID:24454694

Hayat, Tasawar; Shafiq, Anum; Alsaedi, Ahmed

2014-01-01

224

Iron Phosphate Glass for Vitrifying Hanford AZ102 LAW in Joule Heated and Cold Crucible Induction Melters  

SciTech Connect

An iron phosphate composition for vitrifying a high sulfate (~17 wt%) and high alkali (~80 wt%) low activity Hanford waste, known as AZ102 LAW, has been developed for processing in a Joule Heated Melter (JHM) or a Cold Crucible Induction Melter (CCIM). This composition produced a glass waste form, designated as MS26AZ102F-2, with a waste loading of 26 wt% of the AZ102 which corresponded to a total alkali and sulfate (SO3) content of 21 and 4.2 wt%, respectively. A slurry (7M Na) of MS26AZ102F-2 simulant was melted continuously at temperatures between 1030 and 1090°C for 10 days in a small JHM at PNNL and for 7 days in a CCIM at INL. The as-cast glasses produced in both melters and in trial laboratory experiments along with their CCC-treated counterparts met the DOE LAW requirements for the Product Consistency Test (PCT) and the Vapor Hydration Test (VHT). These glass waste forms retained up to 77 % of the SO3 (3.3 wt%), 100% of the Cesium, and 33 to 44% of the rhenium, surrogate for Tc-99, all of which either exceeded or were comparable to the retention limit for these species in borosilicate glass nuclear waste form. Analyses of commercial K-3 refractory lining and the Inconel 693 metal electrodes used in JHM indicated only minimum corrosion of these components by the iron phosphate glass. This is the first time that an iron phosphate composition (slurry feed) was melted continuously in the JHM and CCIM, thereby, demonstrating that iron phosphate glasses can be used as alternative hosts for vitrifying nuclear waste.

Day, Delbert E.; Brow, R. K.; Ray, C. S.; Kim, Cheol-Woon; Reis, Signo T.; Vienna, John D.; Peeler, David K.; Johnson, Fabienne; Hansen, E. K.; Sevigny, Gary J.; Soelberg, Nicolas R.; Pegg, Ian L.; Gan, Hao

2012-01-05

225

Application of High-Speed Infrared Imaging to Study Transient Joule Heating in Station Class Zinc Oxide Surge Arresters  

SciTech Connect

Zinc Oxide based surge arresters are widely used to safeguard and improve reliability of the electrical power delivering and transmission systems. The primary application of surge arresters is to protect valuable components such as transformers from lightning strikes and switching transients in the transmission lines. Metal-oxide-varistor blocks (MOV, e.g. ZnO) are used in surge arrester assemblies. ORNL has developed an advanced infrared imaging technique to monitor the joule heating during transient heating of small varistors. In a recent short-term R&D effort, researchers from ABB and ORNL have expanded the use of IR imaging to larger station-class arrester blocks. An on-site visit to the ABB facility demonstrated that the use of IR imaging is not only feasible but also has the potential to improve arrester quality and reliability. The ASEA Brown Bower (ABB) Power and Technology & Development Company located at Greensburg PA having benefited from collaborative R&D cooperation with ORNL. ABB has decided a follow-on CRADA project is very important. While the previous efforts to study surge arresters included broader studies of IR imaging and computer modeling, ABB has recognized the potential of IR imaging, decided to focus on this particular area. ABB plans to use this technique to systematically study the possible defects in the arrester fabrication process. ORNL will improve the real-time monitoring capability and provide analysis of the infrared images. More importantly, the IR images will help us understand transient heating in a ceramic material from the scientific standpoint. With the improved IR imaging ABB and ORNL will employ the IR system to visualize manufacturing defects that could not be detected otherwise. The proposed on-site tests at ABB Power Technology & Development processing facility will identify the defects and also allow quick adjustments to be made since the resulting products can be inspected immediately. ABB matched the DOE $50K funding with $50K funds-in to ORNL. ABB also provided about $75K in-kind effort for on-site testing, and R&D to improve the fabrication process.

Dinwiddie, R. B.; Wang, H.; Johnnerfelt, B.

2004-03-15

226

Numerical calculation and experimental research on crack arrest by detour effect and joule heating of high pulsed current in remanufacturing  

NASA Astrophysics Data System (ADS)

The remanufacturing blanks with cracks were considered as irreparable. With utilization of detour effect and Joule heating of pulsed current, a technique to arrest the crack in martensitic stainless steel FV520B is developed. According to finite element theory, the finite element(FE) model of the cracked rectangular specimen is established firstly. Then, based on electro-thermo-structure coupled theory, the distributions of current density, temperature field, and stress field are calculated for the instant of energizing. Furthermore, the simulation results are verified by some corresponding experiments performed on high pulsed current discharge device of type HCPD-I. Morphology and microstructure around the crack tip before and after electro pulsing treatment are observed by optical microscope(OM) and scanning electron microscope(SEM), and then the diameters of fusion zone and heat affected zone(HAZ) are measured in order to contrast with numerical calculation results. Element distribution, nano-indentation hardness and residual stress in the vicinity of the crack tip are surveyed by energy dispersive spectrometer(EDS), scanning probe microscopy(SPM) and X-ray stress gauge, respectively. The results show that the obvious partition and refined grain around the crack tip can be observed due to the violent temperature change. The contents of carbon and oxygen in fusion zone and HAZ are higher than those in matrix, and however the hardness around the crack tip decreases. Large residual compressive stress is induced in the vicinity of the crack tip and it has the same order of magnitude for measured results and numerical calculation results that is 100 MPa. The relational curves between discharge energies and diameters of the fusion zone and HAZ are obtained by experiments. The difference of diameter of fusion zone between measured and calculated results is less than 18.3%. Numerical calculation is very useful to define the experimental parameters. An effective method to prevent further extension of the crack is presented and can provide a reference for the compressor rotor blade remanufacturing.

Yu, Jing; Zhang, Hongchao; Deng, Dewei; Hao, Shengzhi; Iqbal, Asif

2014-07-01

227

Effect of the joule heating on the quantum efficiency and choice of thermal conditions for high-power blue InGaN/GaN LEDs  

SciTech Connect

The heat model of a light-emitting diode (LED) with an InGaN/GaN quantum well (QW) in the active region is considered. Effects of the temperature and drive current, as well as of the size and material of the heat sink on the light output and efficiency of blue LEDs are studied. It is shown that, for optimal heat removal, decreasing of the LED efficiency as current increases to 100 mA is related to the effect of electric field on the efficiency of carrier injection into the QW. As current further increases up to 400 mA, the decrease in efficiency is caused by Joule heating. It is shown that the working current of LEDs can be increased by a factor of 5-7 under optimal heat removal conditions. Recommendations are given on the cooling of LEDs in a manner dependent on their power.

Efremov, A. A. [St. Petersburg State Polytechnical University (Russian Federation)], E-mail: eartm@mail.ru; Bochkareva, N. I.; Gorbunov, R. I.; Lavrinovich, D. A.; Rebane, Yu. T.; Tarkhin, D. V.; Shreter, Yu. G. [Russian Academy of Sciences, Ioffe Physicotechnical Institute (Russian Federation)

2006-05-15

228

Joule-heating effects in mixed electroosmotic and pressure-driven microflows under constant wall heat flux  

Microsoft Academic Search

Heat-transfer characteristics of mixed electro-osmotic and pressure-driven flows are obtained in a two-dimensional straight\\u000a microchannel by a solving steady-state energy equation. Both thermally developing and fully developed regions are considered\\u000a for hydraulically fully developed mixed flows under isoflux channel wall conditions. The steady temperature distribution is\\u000a obtained from the superposition of homogeneous solution and particular function. The particular solution is

Keisuke Horiuchi; Prashanta Dutta; Akram Hossain

2006-01-01

229

Joule heating effect on oxide whisker growth induced by current stressing in Cu/Sn-58Bi/Cu solder joint  

NASA Astrophysics Data System (ADS)

The electromigration test was conducted in Cu/Sn-58Bi/Cu solder joint with high current density of 104 A/ cm2. Results showed that a large number of whiskers with natural weed appearance were observed at the cathode side in such a short current stressing time. Furthermore, some secondary whiskers were attached to the primary whiskers, which has never been reported before. We presumed the vapor-solid (VS) mechanism to explain the oxide whiskers growth, which was quite different from the traditional theory that the compressive stress took on the driving force. In conclusion, due to the over-Joule heating effect, the metal oxide whiskers were synthesized in bulk quantities by thermal evaporation of Sn oxide and Bi oxide.

He, Hongwen; Cao, Liqiang; Wan, Lixi; Zhao, Haiyan; Xu, Guangchen; Guo, Fu

2012-08-01

230

The generalized electromagnetic equations and their application: Joule heat (or superconductivity) relative to the generation (or prohibited generation) of net electric charges in a conductor carrying current  

E-print Network

Basing on the conservation law of electric charge and differential geometry, with consulting Maxwell equations, we propose in this paper a set of generalized electromagnetic equations of isotropic media. Maxwell equations can be derived from these equations under certain conditions. And London equations are the special case of them only. These equations are compatible with the Ginzburg-Landau equations and are expected to be valid not only for the normal electromagnetic phenomena but also for the superconducting ones. As the simple applications, we derive the Ohm's law from these equations with the condition of an infinitely long straight circular wire carrying a stationary current; and show that the Joule heat is relative to the net electric charges generated in the wire, which leads to such an interesting picture: for a steady current, the normal state is that arousing net electric charges with the current; while the superconducting state is that prohibiting the generation of net electric charges. In the re...

She, Weilong

2011-01-01

231

A governing parameter for the melting phenomenon at nanocontacts by Joule heating and its application to joining together two thin metallic wires  

SciTech Connect

For cutting and joining extremely thin metallic wires, the issue of Joule heating in the wires is considered. The middle of a section of a thin Pt wire with a diameter of about 800 nm was melted locally by a direct current supply, and the wire was cut at a predetermined point by applying a force to shear the molten part of the wire. Furthermore, a constant current was applied to a system in which the free ends of two Pt wires were contacted, and the wires were joined together. A parameter, which governs the melting phenomenon at the point of contact of very thin wires, is proposed. It was verified that the conditions required for joining thin wires were able to be determined by the parameter that depends on the applied current, the length and cross sectional area of the wires, and a function of the geometrical quantities for calibrating the thermal conditions.

Tohmyoh, Hironori [Department of Nanomechanics, Tohoku University, Aoba 6-6-01, Aramaki, Aoba-ku, Sendai 980-8579 (Japan)

2009-01-01

232

Unsteady magnetohydrodynamic Hartmann-Couette flow and heat transfer in a Darcian channel with Hall current, ionslip, viscous and Joule heating effects: Network numerical solutions  

NASA Astrophysics Data System (ADS)

A theoretical study of unsteady magnetohydrodynamic viscous Hartmann-Couette laminar flow and heat transfer in a Darcian porous medium intercalated between parallel plates, under a constant pressure gradient is presented. Viscous dissipation, Joule heating, Hall current and ionslip current effects are included as is lateral mass flux at both plates. The dimensionless conservation equations for the primary ( x?-direction), secondary ( z?-direction) momentum and also energy conservation equation are derived and solved using a computational technique known as Network Simulation Methodology (NSM). Velocity distributions ( u?, w?) and temperature distribution ( T?) at the channel centre ( y? = 0) over time ( t?) are studied graphically for the effects of Darcy number ( Da), Hartmann number ( Ha), transpiration ( Nt), Hall current parameter ( Be), ionslip parameter ( Bi), pressure gradient parameter (d P/d x?) with Prandtl number prescribed at 7.0 (electrically conducting water), Eckert number held constant at 0.25 (heat convection from the plates to the fluid) and Reynolds number ( Re) fixed at 5.0 (for Re < 10, Darcian model is generally valid). Increasing Darcy number causes an increase in temperature, T?; values are however significantly reduced for the higher Hartmann number case ( Ha = 10). For the case of low transpiration (i.e. Nt = 1 which corresponds to weak suction at the upper plate and weak injection at the lower plate), both primary velocity ( u?) and secondary velocity ( w?) are increased with a rise in Darcy number (owing to a simultaneous decrease in Darcian porous drag); temperature T? is also increased considerably with increasing Da. However, for stronger transpiration ( Nt = 10), magnitudes of u?, w? and T? are significantly reduced and also significant overshoots are detected prior to the establishment of steady state flow. With increasing Hall current parameter, Be, (for the purely fluid regime i.e. Da ? ?), primary velocity is considerably increased, whereas secondary velocity is reduced; temperatures are decreased in the early stages of flow but effectively increased in the steady state with increasing Be. With strong Darcian drag present ( Da = 0.01 i.e. very low permeability), magnitudes of u?, w? and T? are considerably reduced and temperatures are found to be reduced for all t?, with increasing Hall current effect ( Be). Increasing ionslip current parameter ( Bi) increases primary velocity ( u?), decreases secondary velocity ( w?) and also temperature ( T?) for all time ( t?), in the infinite permeability case ( Da ? ?). For weakly Darcian flow, ionslip parameter ( Bi) has a much reduced effect on the velocity distributions. Temperature, T? is strongly increased with a rise in pressure gradient parameter, d P?/d x?, as is primary velocity ( u?); however, secondary velocity ( w?) is reduced. The present study has applications in hybrid magnetohydrodynamic (MHD) energy generators, materials processing, geophysical hydromagnetics, etc.

Bég, O. Anwar; Zueco, Joaquín; Takhar, H. S.

2009-04-01

233

The joule balance in NIM of China  

NASA Astrophysics Data System (ADS)

The advantage of the joule balance over the classic watt balance is that the dynamic measurement in the watt balance is replaced by a static measurement, which makes the whole measurement procedure easier. The main problems in the joule balance are the precise measurement of mutual inductance and coil heating. These problems and recent progress in the development of the joule balance are described and discussed in this paper. The whole system is at the stage of being adjusted and improved. The principle of the joule balance has been demonstrated by a measurement of the Planck constant, h = 6.626?104(59) × 10-34 J s with an 8.9 ppm measurement uncertainty.

Zhonghua, Zhang; Qing, He; Zhengkun, Li; Bing, Han; Yunfeng, Lu; Jiang, Lan; Chen, Li; Shisong, Li; Jinxin, Xu; Nong, Wang; Gang, Wang; Hongzhi, Gong

2014-04-01

234

Ionospheric Joule heating, fast flow channels, and magnetic field line topology for IMF By-dominant conditions: Observations and comparisons with predicted reconnection jet speeds  

NASA Astrophysics Data System (ADS)

When the interplanetary magnetic field (IMF) is dawnward or duskward, magnetic merging between the IMF and the geomagnetic field occurs near the cusp on the dayside flanks of the magnetosphere. While these periods are usually considered “quiet,” they can lead to intense localized energy deposition into the dayside ionosphere. We analyze two intervals during the geomagnetic storm on 24 August 2005: one with steady duskward IMF and one with steady dawnward IMF. Using outputs from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) and data from the Defense Meteorological Satellite Program, we show that intense Joule heating exists on fast ionospheric flow channels which lie on open field lines. In addition, the flow channels on open field lines have large components in the sunward direction and therefore resist the bulk solar wind and magnetosheath flow. We compare observed velocities with predicted reconnection jet speeds using magnetosheath and cusp parameters from an MHD simulation. Results suggest that the fast ionospheric flow corresponds to portions of the reconnection jet populated by low-density plasma. The importance of ionospheric conductance in determining the ionospheric flow is also discussed.

Wilder, F. D.; Crowley, G.; Eriksson, S.; Newell, P. T.; Hairston, M. R.

2012-11-01

235

Ionospheric Joule heating, fast flow channels, and magnetic field line topology for IMF By-dominant conditions - Observations and comparisons with predicted reconnection jet speeds  

NASA Astrophysics Data System (ADS)

When the interplanetary magnetic field (IMF) is dawnward or duskward, magnetic merging between the IMF and the geomagnetic field occurs near the cusp on the dayside flanks of the magnetosphere. While these periods are usually considered "quiet," they can lead to intense localized energy deposition into the dayside ionosphere. We analyze two intervals during the geomagnetic storm on August 24, 2005: one with steady duskward IMF and one with steady dawnward IMF. Using outputs from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) and data from the Defense Meteorological Satellite Program, we show that intense Joule heating exists on fast ionospheric flow channels which lie on open field lines. In addition, the flow channels on open field lines have large components in the sunward direction, and therefore resist the bulk solar wind and magnetosheath flow. We compare observed velocities with predicted reconnection jet speeds using magnetosheath and cusp parameters from an MHD simulation. Results suggest that the fast ionospheric flow corresponds to portions of the reconnection jet populated by low density plasma. The importance of ionospheric conductance in determining the ionospheric flow is also discussed.

Wilder, F. D.; Crowley, G.; Eriksson, S.; Newell, P. T.; Hairston, M. R.

2012-12-01

236

Exciton quenching by diffusion of 2,3,5,6-tetrafluoro-7,7',8,8'-tetra cyano quino dimethane and its consequences on joule heating and lifetime of organic light-emitting diodes.  

PubMed

In this Letter, the effect of F(4)-TCNQ insertion at the anode/hole transport layer (HTL) interface was studied on joule heating and the lifetime of organic light-emitting diodes (OLEDs). Joule heating was found to reduce significantly (pixel temperature decrease by about 10 K at a current density of 40 mA/cm(2)) by this insertion. However, the lifetime was found to reduce significantly with a 1 nm thick F(4)-TCNQ layer, and it improved by increasing the thickness of this layer. Thermal diffusion of F(4)-TCNQ into HTL leads to F(4)-TCNQ ionization by charge transfer, and drift of these molecules into the emissive layer caused faster degradation of the OLEDs. This drift was found to reduce with an increase in the thickness of F(4)-TCNQ. PMID:24081070

Tyagi, Priyanka; Kumar, Arunandan; Giri, Lalat Indu; Dalai, Manas Kumar; Tuli, Suneet; Kamalasanan, M N; Srivastava, Ritu

2013-10-01

237

Viscous dissipation and Joule heating effects on MHD-free convection from a vertical plate with power-law variation in surface temperature in the presence of Hall and ion-slip currents  

Microsoft Academic Search

An analysis is presented to study the effects of viscous dissipation and Joule heating on MHD-free convection flow past a semi-infinite vertical flat plate in the presence of the combined effect of Hall and ion-slip currents for the case of power-law variation of the wall temperature. The fluid is permeated by a strong transverse magnetic field imposed perpendicularly to the

Emad M. Abo-Eldahab; Mohamed A. El Aziz

2005-01-01

238

Direct Observation of Nanoscale Peltier and Joule Effects at Metal-Insulator Domain Walls in Vanadium Dioxide Nanobeams  

E-print Network

localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domain, Joule heating, metal-insulator domain wall Strongly correlated materials share a unique feature whereDirect Observation of Nanoscale Peltier and Joule Effects at Metal- Insulator Domain Walls

Wu, Junqiao

239

Every Joule is Precious Carla Schlatter Ellis  

E-print Network

the resource management functions of the Operating System � Low level Fine grain Low-power Circuits SoftwareEvery Joule is Precious Carla Schlatter Ellis Duke University Systems & Architecture Milly Watt problem (& not just for mobile computing) � Reducing heat production and fan noise � Extending battery

Ellis, Carla

240

Cascade Joule-Thomson refrigerators  

NASA Astrophysics Data System (ADS)

The design criteria for cascade Joule-Thomson refrigerators for cooling in the temperature range from 300 K to 4.2 K were studied. The systems considered use three or four refrigeration stages with various working gases to achieve the low temperatures. Each stage results in cooling to a progressively lower temperature and provides cooling at intermediate temperatures to remove the substantial amount of parasitic heat load encountered in a typical dewar. With careful dewar design considerable cooling can be achieved with moderate gas flows. For many applications, e.g., in the cooling of sensitive sensors, the fact that the refrigerator contains no moving parts and may be remotely located from the gas source is of considerable advantage. A small compressor suitable for providing the gas flows required was constructed.

Tward, E.; Steyert, W. A.

1983-12-01

241

Metal-insulator transition in free-standing VO2/TiO2 microstructures through low-power Joule heating  

NASA Astrophysics Data System (ADS)

We investigated voltage bias-driven electronic phase switching from insulating to metallic states in the VO2 thin films having freestanding structures (FSS) and non-freestanding structures (N-FSS). By measuring the electrical power during switching under different thermal conditions, we found that the thermal coupling of the microstructures determined the spatial temperature distribution on the device and strongly affected the efficiency of the insulator-metal switching induced by the Joule effect. The power required for switching in the FSS was two orders lower than that for the N-FSS. This indicates that an appropriate design of the thermal flow is a fundamental issue for developing efficient switching and memristive devices.

Yamasaki, Syota; Kanki, Teruo; Manca, Nicola; Pellegrino, Luca; Marré, Daniele; Tanaka, Hidekazu

2014-02-01

242

Effect of the joule heating on the quantum efficiency and choice of thermal conditions for high-power blue InGaN\\/GaN LEDs  

Microsoft Academic Search

The heat model of a light-emitting diode (LED) with an InGaN\\/GaN quantum well (QW) in the active region is considered. Effects\\u000a of the temperature and drive current, as well as of the size and material of the heat sink on the light output and efficiency\\u000a of blue LEDs are studied. It is shown that, for optimal heat removal, decreasing of

A. A. Efremov; N. I. Bochkareva; R. I. Gorbunov; D. A. Lavrinovich; Yu. T. Rebane; D. V. Tarkhin; Yu. G. Shreter

2006-01-01

243

Sensors and Actuators B 127 (2007) 5462 Wireless Joule nanoheaters  

E-print Network

Sensors and Actuators B 127 (2007) 54­62 Wireless Joule nanoheaters Christian Falconia,b,, Arnaldo, and in vivo monitoring of physiological parameters. In this article, we theoretically study the possibility, the selectiv- ity (i.e. the ability to selectively deliver drugs or to heat only the target cells) may

Wang, Zhong L.

244

Multicomponent gas sorption Joule-Thomson refrigeration  

NASA Technical Reports Server (NTRS)

The present invention relates to a cryogenic Joule-Thomson refrigeration capable of pumping multicomponent gases with a single stage sorption compressor system. Alternative methods of pumping a multicomponent gas with a single stage compressor are disclosed. In a first embodiment, the sorbent geometry is such that a void is defined near the output of the sorption compressor. When the sorbent is cooled, the sorbent primarily adsorbs the higher boiling point gas such that the lower boiling point gas passes through the sorbent to occupy the void. When the sorbent is heated, the higher boiling point gas is desorbed at high temperature and pressure and thereafter propels the lower boiling point gas out of the sorption compressor. A mixing chamber is provided to remix the constituent gases prior to expansion of the gas through a Joule-Thomson valve. Other methods of pumping a multicomponent gas are disclosed. For example, where the sorbent is porous and the low boiling point gas does not adsorb very well, the pores of the sorbent will act as a void space for the lower boiling point gas. Alternatively, a mixed sorbent may be used where a first sorbent component physically adsorbs the high boiling point gas and where the second sorbent component chemically absorbs the low boiling point gas.

Jones, Jack A. (inventor); Petrick, S. Walter (inventor); Bard, Steven (inventor)

1991-01-01

245

A finite element model of EDM based on the Joule effect  

Microsoft Academic Search

A thermal–electrical model was developed for sparks generated by electrical discharge in a liquid media. A cylindrical shape has been used for the discharge channel created between the electrodes. The discharge channel being an electrical conductor will dissipate heat, which can be explained by the Joule heating effect. The amount of heat dissipated varies with the thermal–physical properties of the

J. Marafona; J. A. G. Chousal

2006-01-01

246

Detailed Heat Generation Simulations via the Monte Carlo Method  

E-print Network

details of Joule heating in bulk silicon with Monte Carlo simulations including acoustic and optical and particularly relevant to the heating and reliability of nanoscale and thin-film transistors. Joule heating, as in most semiconductors, high-field Joule heating is typically dominated by optical phonon emission

Dutton, Robert W.

247

Room temperature fast synthesis of zinc oxide nanowires by inductive heating  

E-print Network

layer and provides rapid Joule heating for nanowire synthesis. Analytically, one can derive each coil% of the Joule heating occurs, is Room temperature fast synthesis of zinc oxide nanowires by inductive heating Lei Luo,a Brian D

Lin, Liwei

248

Shock-Wave Compression and Joule-Thomson Expansion  

NASA Astrophysics Data System (ADS)

Structurally stable atomistic one-dimensional shock waves have long been simulated by injecting fresh cool particles and extracting old hot particles at opposite ends of a simulation box. The resulting shock profiles demonstrate tensor temperature, Txx?Tyy and Maxwell's delayed response, with stress lagging strain rate and heat flux lagging temperature gradient. Here this same geometry, supplemented by a short-ranged external "plug" field, is used to simulate steady Joule-Kelvin throttling flow of hot dense fluid through a porous plug, producing a dilute and cooler product fluid.

Hoover, Wm. G.; Hoover, Carol G.; Travis, Karl P.

2014-04-01

249

Local heating of heterogeneous current-carrying conductors Yu. Dolinskya)  

E-print Network

's surface. We analyze different components of Joule heating, which are associated with the change on structural material changes in conductors is Joule heating. A separate investigation of the effect of JouleLocal heating of heterogeneous current-carrying conductors Yu. Dolinskya) and T. Elperina

Elperin, Tov

250

Energy deposition by precipitating particles and Joule dissipation in the auroral ionosphere  

Microsoft Academic Search

Eight days of synoptic data from the Chatanika incoherent scatter radar have been analyzed in an attempt to determine the characteristic morphology of auroral zone energy deposition by Joule heating and precipitating particles. The observations cover invariant latitudes between approx.62° and 68°. The composite spatial morphology derived from these eight days of data shows that morning sector particle precipitation deposits

James F. Vickrey; Richard R. Vondrak; Stephen J. Matthews

1982-01-01

251

Direct observation of nanometer-scale Joule and Peltier effects in phase change memory devices  

NASA Astrophysics Data System (ADS)

We measure power dissipation in phase change memory (PCM) devices by scanning Joule expansion microscopy (SJEM) with ˜50 nm spatial and 0.2 K temperature resolution. The temperature rise in the Ge2Sb2Te5 (GST) is dominated by Joule heating, but at the GST-TiW contacts it is a combination of Peltier and current crowding effects. Comparison of SJEM and electrical measurements with simulations of the PCM devices uncovers a thermopower of ˜350 ?V K-1 and a contact resistance of ˜2.0 × 10-8 ? m2 (to TiW) for 25 nm thick films of face centered-cubic crystalline GST. Knowledge of such nanometer-scale Joule, Peltier, and current crowding effects is essential for energy-efficient design of future PCM technology.

Grosse, Kyle L.; Xiong, Feng; Hong, Sungduk; King, William P.; Pop, Eric

2013-05-01

252

The Joule–Thomson effect in natural gas flow-rate measurements  

Microsoft Academic Search

A numerical procedure for the calculation of the Joule–Thomson (JT) coefficient of a natural gas is derived. The AGA-8 extended virial-type characterization equation is used to calculate the rate of change of the compression factor with respect to the temperature at constant pressure. The DIPPR\\/AIChE generic ideal heat capacity equations are used to derive the molar heat capacity of a

Ivan Mari?

2005-01-01

253

Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices  

NASA Astrophysics Data System (ADS)

This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 ?V K-1. This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale.

Grosse, Kyle L.; Pop, Eric; King, William P.

2014-09-01

254

Nanometer-scale temperature imaging for independent observation of Joule and Peltier effects in phase change memory devices.  

PubMed

This paper reports a technique for independent observation of nanometer-scale Joule heating and thermoelectric effects, using atomic force microscopy (AFM) based measurements of nanometer-scale temperature fields. When electrical current flows through nanoscale devices and contacts the temperature distribution is governed by both Joule and thermoelectric effects. When the device is driven by an electrical current that is both periodic and bipolar, the temperature rise due to the Joule effect is at a different harmonic than the temperature rise due to the Peltier effect. An AFM tip scanning over the device can simultaneously measure all of the relevant harmonic responses, such that the Joule effect and the Peltier effect can be independently measured. Here we demonstrate the efficacy of the technique by measuring Joule and Peltier effects in phase change memory devices. By comparing the observed temperature responses of these working devices, we measure the device thermopower, which is in the range of 30 ± 3 to 250 ± 10 ?V K(-1). This technique could facilitate improved measurements of thermoelectric phenomena and properties at the nanometer-scale. PMID:25273761

Grosse, Kyle L; Pop, Eric; King, William P

2014-09-01

255

Performance optimization of a miniature Joule-Thomson cryocooler using numerical model  

NASA Astrophysics Data System (ADS)

The performance of a miniature Joule-Thomson cryocooler depends on the effectiveness of the heat exchanger. The heat exchanger used in such cryocooler is Hampson-type recuperative heat exchanger. The design of the efficient heat exchanger is crucial for the optimum performance of the cryocooler. In the present work, the heat exchanger is numerically simulated for the steady state conditions and the results are validated against the experimental data available from the literature. The area correction factor is identified for the calculation of effective heat transfer area which takes into account the effect of helical geometry. In order to get an optimum performance of the cryocoolers, operating parameters like mass flow rate, pressure and design parameters like heat exchanger length, helical diameter of coil, fin dimensions, fin density have to be identified. The present work systematically addresses this aspect of design for miniature J-T cryocooler.

Ardhapurkar, P. M.; Atrey, M. D.

2014-09-01

256

The Physics of Heat Transport in Semiconductor Lasers Kevin P. Pipe and Rajeev J. Ram  

E-print Network

is given in addition to Joule and recombination heating. Optimized devices and thermal measurements identified several sources of heating (Joule heating, radiation absorption, contact heating, and nonThe Physics of Heat Transport in Semiconductor Lasers Kevin P. Pipe and Rajeev J. Ram Research

257

Mixed refrigerant Joule-Thomson sorption cryocoolers  

NASA Astrophysics Data System (ADS)

Joule-Thomson (JT) sorption cryocooling is the most mature technology for cooling from a normal Room-Temperature (RT) down to temperatures below 100 K in the absence of moving parts. Therefore, high reliability and no vibrations are attainable, in comparison with other cryocoolers. Cooling to 80 - 100 K with JT cryocoolers is often implemented with pure nitrogen. Alternatively, mixed refrigerants have been suggested for reducing the operating pressures to enable closed cycle cryocooling. There is a variety of publications describing nitrogen sorption cryocoolers with different configurations of sorption compressors. In the present research we suggest a novel sorption JT cryocooler that operates with a mixed refrigerant. Merging of sorption cryocooling and a mixed refrigerant enables the use of a simple, single stage compressor for cooling to 80 - 100 K, lower operating temperatures of the sorption cycle, and thus - reduced power consumption. In previous studies we have analyzed sorption compressors for mixed gases and mixed refrigerants for JT cryocoolers, separately. In this paper the option of mixed refrigerant sorption JT cryocoolers is explored. The considerations for developing mixed refrigerants to be driven by sorption compressors and to be utilized with JT cryocoolers are provided. It appears that, unlike with pure nitrogen, mixed refrigerants can be suitable for JT cryocooling with a single stage sorption compressor.

Tzabar, Nir; Grossman, Gershon

2014-01-01

258

Electrical probe storage using Joule heating in phase change media  

NASA Astrophysics Data System (ADS)

We demonstrate the feasibility of ultrahigh-density probe recording in chalcogenide-based phase change media. The multilayer medium has been optimized with respect to electrical, thermal, and tribological requirements. Design of the multilayer takes into account the nonlinear dependence of the electrical properties of the phase change layer with respect to both electrical field and temperature. Memory dots as small as 15nm have been written and read repeatably. Data storage density of greater than Tbit /in.2 density has been successfully achieved.

Gidon, S.; Lemonnier, O.; Rolland, B.; Bichet, O.; Dressler, C.; Samson, Y.

2004-12-01

259

Effect of Joule heating on the determination of electromigration parameters  

Microsoft Academic Search

The use of accelerated electromigration (EM) wafer level reliability (WLR) tests aims at performing tests on a large sample size faster than at package level (PLR). Meanwhile, the correlation of times to failure determined from package level tests and wafer level tests is sometimes not obvious. Therefore, little trust is put in extrapolated lifetime determined from WLR tests. To elucidate

X. Federspiel; V. Girault; D. Ney

2003-01-01

260

Photon Generation by Joule Heating in Metal Films  

Microsoft Academic Search

We calculate the evolution of the coupled electron-phonon system in a metal film subjected to an electric field. The detailed form of the phonon distribution is presented, and is shown to deviate significantly from a Bose distribution.

N. Perrin; H. Budd

1972-01-01

261

Stochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a)  

E-print Network

the mean-free-path is small as compared to and to colli- sional Joule heating. In region B, L, electrons plasma boundary at x L. But contrary to the Joule heating, this hybrid heating is nonlocal: the placeStochastic electron heating in bounded radio-frequency plasmas I. D. Kaganovich,a) V. I. Kolobov

Kaganovich, Igor

262

JouleSort: a balanced energy-efficiency benchmark  

Microsoft Academic Search

The energy eciency of computer systems is an important concern in a variety of contexts. In data centers, reducing energy use improves operating cost, scalability, reliability, and other factors. For mobile devices, energy consumption directly aects functionality and usability. We propose and motivate JouleSort, an external sort benchmark, for evaluat- ing the energy eciency of a wide range of computer

Suzanne Rivoire; Mehul A. Shah; Parthasarathy Ranganathan; Christos Kozyrakis

2007-01-01

263

The similarity law for the joule-thomson inversion line.  

PubMed

We show that the expression for the Joule-Thomson inversion temperature following from the van der Waals equation and recorded in a form reduced to the Boyle values has a universal character and can be applied to many real substances and model systems. PMID:25271782

Apfelbaum, E M; Vorob'ev, V S

2014-10-23

264

Determination of cyclamate in low joule foods by capillary zone electrophoresis with indirect ultraviolet detection  

Microsoft Academic Search

A rapid method for the determination of cyclamate in low joule cordials and other low joule foods by capillary zone electrophoresis (CZE) with indirect ultraviolet (UV) detection at 254 nm is described. Sorbic acid, which is often added to low joule cordials as a preservative, can also be determined with this procedure. Cyclamate and sorbate are well separated from the

Catherine O. Thompson; V. Craige Trenerry; Bridget Kemmery

1995-01-01

265

INFLUENCE OF END POTENTIAL PLATES ON PLASMA HEATING AND CONFINEMENT Sergey Yu. Taskaev  

E-print Network

temperature. It was detected that this «non-joule» non-turbulent effective heating of electrons was relatedW) and Joule heating concerning Spitzer conductivity (1 kW) -- are not enough for balance. Does that meanINFLUENCE OF END POTENTIAL PLATES ON PLASMA HEATING AND CONFINEMENT Sergey Yu. Taskaev Budker

Taskaev, Sergey Yur'evich

266

Optimization of the working fluid in a Joule-Thomson cold stage  

NASA Astrophysics Data System (ADS)

Vibration-free miniature Joule-Thomson (JT) coolers are of interest for cooling a wide variety of devices, including low-noise amplifiers, semiconducting and superconducting electronics, and small optical detectors used in space applications. For cooling such devices, coolers are needed which have operating temperatures within a wide temperature range of 2-250 K. In this paper, the optimization of the working fluid in JT cold stages is described that operate at different temperatures within that range. For each temperature, the most suitable working fluid is selected on the basis of the coefficient of performance of the cold stage, which is defined as the ratio of the gross cooling power to the change in Gibbs free energy of the fluid during compression. In addition, a figure of merit of the heat exchange in the counter-flow heat exchanger is evaluated that depends only on the properties of the working fluid.

Derking, J. H.; ter Brake, H. J. M.; Sirbi, A.; Linder, M.; Rogalla, H.

2009-03-01

267

Heat management in aluminum\\/air batteries: Sources of heat  

Microsoft Academic Search

One of the problems with the aluminum\\/air battery is the generation of heat, during both idle and discharge periods. The main sources of heat are: (1) corrosion of the aluminum anode during the idle period; (2) inefficient, or less efficient, dissolution of anode during discharge; (3) Joule heat during discharge, and (4) non-uniform mass transfer during both discharge and idle

R. S. M. Patnaik; S. Ganesh; G. Ashok; M. Ganesan; V. Kapali

1994-01-01

268

hal-00168638,version2-6Sep2007 Electron heating in metallic resistors at sub-Kelvin temperature  

E-print Network

) In the presence of Joule heating, the electronic temperature in a metallic resistor placed at sub- Kelvin-temperature exper- iments, this procedure is problematic because of Joule heating, which can affect the temperaturehal-00168638,version2-6Sep2007 Electron heating in metallic resistors at sub-Kelvin temperature B

Paris-Sud XI, Université de

269

Design of a valved moving magnet type linear compressor for a Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

For temperatures around 4-6 K, Joule-Thomson (J-T) cryocoolers can achieve a higher efficiency than Stirling or pulse tube cryocoolers thus have been widely used in space. It is crucial for a J-T compressor to obtain a relatively high pressure ratio. With this concept, a valved moving magnet type linear compressor has been designed. This paper describes the design method and component structure of the linear compressor in detail. The electromagnetic force of linear motor, stiffness and stress distribution of flexure springs were calculated based on finite element method (FEM). System resonance was specially considered to achieve a high efficiency, and system vibration and heat dissipation problems were discussed. The design goal of the linear compressor is to achieve an efficiency of 80% and a lifetime longer than 5 years.

Wang, W. W.; Wang, L. Y.; Gan, Z. H.

2014-01-01

270

Gifford-McMahon/Joule-Thomson Refrigerator Cools to 2.5 K  

NASA Technical Reports Server (NTRS)

A compact refrigerator designed specifically for cooling a microwave maser low-noise amplifier is capable of removing heat at a continuous rate of 180 mW at a temperature of 2.5 K. This refrigerator is a combination of (1) a commercial Gifford-McMahon (GM) refrigerator nominally rated for cooling to 4 K and (2) a Joule-Thomson (J-T) circuit. The GM refrigerator pre-cools the J-T circuit, which provides the final stage of cooling. The refrigerator is compact and capable of operating in any orientation. Moreover, in comparison with a typical refrigerator heretofore used to cool a maser to 4.5 K, this refrigerator is simpler and can be built at less than half the cost.

Britcliffe, Michael; Fernandez, Jose; Hanson, Theodore

2005-01-01

271

Microwave heating-induced DC magnetic flux penetration in YBa2Cu3O7-superconducting thin films Julien Kermorvant,1  

E-print Network

that it is simply local Joule heating of the superconducting film by the microwave field that leads to the nonlinear to Joule heating, with a lin- ear response dissipation mechanism. Candidate mecha- nisms at the originMicrowave heating-induced DC magnetic flux penetration in YBa2Cu3O7- superconducting thin films

Boyer, Edmond

272

Review of laser mega joule target area: Design and processes  

NASA Astrophysics Data System (ADS)

The French Laser Mega Joule (LMJ) target area is currently designed to achieve ignition and significant fusion gain in the laboratory. Design studies for target equipments are well advanced, target chamber and target area frame (concrete) is even started. A detailed overview of the target area equipments is presented: target chamber, frame, diagnostic inserter manipulator, final optic assembly, dual diagnostic and laser reference, non cryogenic target positioner. Recent technical and architectural choices are detailed including safety transfers and alignment processes (target, laser and diagnostic). All these target equipments allow to optimize shot chronogram, from target metrology to the shot, including calibration process.

Geitzholz, M.; Lanternier, C.

2006-06-01

273

Joule-Thomson Cooling Due to CO2 Injection into Natural GasReservoirs  

SciTech Connect

Depleted natural gas reservoirs are a promising target for Carbon Sequestration with Enhanced Gas Recovery (CSEGR). The focus of this study is on evaluating the importance of Joule-Thomson cooling during CO2 injection into depleted natural gas reservoirs. Joule-Thomson cooling is the adiabatic cooling that accompanies the expansion of a real gas. If Joule-Thomson cooling were extreme, injectivity and formation permeability could be altered by the freezing of residual water,formation of hydrates, and fracturing due to thermal stresses. The TOUGH2/EOS7C module for CO2-CH4-H2O mixtures is used as the simulation analysis tool. For verification of EOS7C, the classic Joule-Thomson expansion experiment is modeled for pure CO2 resulting in Joule-Thomson coefficients in agreement with standard references to within 5-7 percent. For demonstration purposes, CO2 injection at constant pressure and with a large pressure drop ({approx}50 bars) is presented in order to show that cooling by more than 20 C can occur by this effect. Two more-realistic constant-rate injection cases show that for typical systems in the Sacramento Valley, California, the Joule-Thomson cooling effect is minimal. This simulation study shows that for constant-rate injections into high-permeability reservoirs, the Joule-Thomson cooling effect is not expected to create significant problems for CSEGR.

Oldenburg, Curtis M.

2006-04-21

274

Performance of a MEMS Heat Exchanger for a Cryosurgical Probe  

Microsoft Academic Search

This paper presents the experimental test results for two 2 nd generation Micro-Electro- Mechanical Systems (MEMS) heat exchangers that are a composite of silicon plates with micro- machined flow passages interleaved with glass spacers. The MEMS heat exchangers were designed for use as the recuperative heat exchanger within a Joule-Thomson (JT) cycle used to energize a cryosurgical probe. The heat

M. J. White; W. Zhu; G. F. Nellis; S. A. Klein; Y. B. Gianchandani

275

Mixed-refrigerant Joule-Thomson (MR JT) mini-cryocoolers  

NASA Astrophysics Data System (ADS)

This paper presents the progress in our ongoing research on Mixed-Refrigerant (MR) Joule-Thomson (JT) cryocoolers. The research begun by exploring different MRs and testing various compressors: oil-lubricated and oil-free, reciprocating and linear, custom-made and commercial. Closed-cycle JT cryocoolers benefit from the fact that the compressor might be located far from the cold-end and thus there are no moving parts, no vibrations, and no heat emission near the cold-end. As a consequence, the compressor may be located where there are no severe size limitations, its heat can be conveniently removed, and it can be easily maintained. However, in some applications there is still a demand for a small compressor to drive a JT cryocooler although it is located far from the cooled device. Recently, we have developed a miniature oil-free compressor for MR JT cryocoolers that weighs about 700 g and its volume equals about 300 cc. The cryocooler operates with a MR that contains Ne, N2, and Hydrocarbons. This MR has been widely investigated with different compressors and varying operating conditions and proved to be stable. The current research investigates the performances of MR JT mini-cryocooler operating with the MR mentioned above, driven with our miniature compressor, and a cold-finger prototype. A Dewar with heat load of about 230 mW is cooled to about 80 K at ambient temperatures between 0°C and 40°C. The experimental results obtained are stable and demonstrate the ability to control the cooling temperature by changing the rotation speed of the compressor.

Tzabar, Nir

2014-01-01

276

Final Report on the Joule-Scale Experimental Demonstration  

SciTech Connect

We describe the final results of the High Power Laser Pulse Recirculation project. We have developed and implementing a novel technique for picosecond, Joule-class laser pulse recirculation inside a passive cavity. The aim of this project was to develop technology compatible with increasing the efficiency of Compton based light sources by more than an order of magnitude. In year 1 of the project, we achieved a greater than 40 times average power enhancement of the mJ-scale laser pulses inside a passive cavity with internal focus. In year 2, we demonstrated recirculation of lasers pulses with energies up to 191 mJ at 532 nm, at a repetition rate of 10 Hz, and a pulse duration of 20 ps. In this high energy regime, we achieved up to 14 times average power enhancement inside the cavity. This enhancement factor is compatible with the new X-band based mono-energetic gamma-ray machine, Velociraptor, being constructed at LLNL. The demonstrated cavity enhancement is primarily limited by the poor spatial beam quality of the high power laser beam. We expect a nearly diffraction limited laser beam to achieve 40 times or better cavity enhancement, as demonstrated in low energy experiments in FY-07. The two primary obstacles to higher average brightness and conversion efficiency of laser pulse energy to gamma-rays are the relatively small Compton scattering cross-section and the typically low repetition rates of Joule-class interaction lasers (10 Hz). Only a small fraction (10{sup -10}) of the available laser photons is converted to gamma-rays, while the rest is discarded. To significantly reduce the average power requirements of the laser and increase the overall system efficiency, we can recirculate laser light for repeated interactions with electron bunches. Our pulse recirculation scheme is based on nonlinear frequency conversion, termed recirculation injection by nonlinear gating (RING), inside a passive cavity. The main objectives of the two year project were: (1) Validate the concept of RING pulse trapping and recirculation technique. Completed Sep. 07 (2) Develop cavity designs compatible with a laser-electron Compton light source. Completed January 08. (3) Demonstrate trapping and recirculation of laser pulses suitable for high brightness gamma-ray generation. Completed Aug. 08 Our project has established RING as a viable technology for enhancing Compton scattering based gamma-ray generation. With sufficient funding we can implement pulse recirculation on the next generation Mono-energetic Gamma-Ray machine under construction at LLNL.

Shverdin, M

2008-10-01

277

Clogging of Joule-Thomson Devices in Liquid Hydrogen-Lunar Lander Descent Stage Operating Regime  

NASA Astrophysics Data System (ADS)

Joule-Thomson (J-T) devices have been identified as critical components for future space exploration missions. The NASA Constellation Program lunar architecture considers LOX/LH2 propulsion for the lunar lander descent stage main engine an enabling technology, ensuring the cryogenic propellants are available at the correct conditions for engine operation. This cryogenic storage system may utilize a Thermodynamic Vent System (TVS) that includes J-T devices to maintain tank fluid pressure and temperature. Previous experimental investigations have indicated that J-T devices may become clogged when flowing LH2 while operating at a temperature range from 20.5 K to 24.4 K. It has been proposed that clogging is due to a trace amount of metastable, supercooled liquid neon in the regular LH2 supply. In time, flow blockage occurs from accretion of solid neon on the orifice. This clogging poses a realistic threat to spacecraft propulsion systems utilizing J-T devices in cryogenic pressure control systems. TVS failure due to J-T clogging would prevent removal of environmental heat from the propellant and potential loss of mission. This report describes J-T clogging tests performed with LH2. Tests were performed in the expected Lunar Lander operating regime, and several methods were evaluated to determine the optimum approach to mitigating the potential risk of J-T clogging.

Jurns, J. M.

2010-04-01

278

On the Joule-Thomson integral inversion curves of quantum gases  

Microsoft Academic Search

The integral inversion curve (IIC) is the contour of all thermodynamic states (P,T) which exhibit a zero integral cooling under Joule-Thomson (isenthalpic) expansion from a pressure, P, down to ambient atmospheric pressure. This is an alternative and complementary presentation of the Joule-Thomson inversion phenomena. The traditional inversion curve is a differential one, namely, it distinguishes between states for which infinitesimal

B.-Z. Maytal; A. Shavit

1997-01-01

279

Clogging of Joule-Thomson Devices in Liquid Hydrogen Handling  

NASA Technical Reports Server (NTRS)

Experiments conducted at the NASA Glenn Research Center indicate that Joule-Thomson devices become clogged when transferring liquid hydrogen (LH2), operating at a temperature range from 20.5 to 24.4 K. Blockage does not exist under all test conditions but is found to be sensitive to the inlet temperature of the LH2. At a subcooled inlet temperature of 20.5 K blockage consistently appears but is dissipated when the fluid temperature is raised above 24.5 K. Clogging steadily reduced flow rate through the orifices, eventually resulting in complete blockage. This tendency poses a threat to spacecraft cryogenic propulsion systems that would utilize passive thermal control systems. We propose that this clogging is due to trace amounts of neon in the regular LH2 supply. Neon freezes at 24.5 K at one atmosphere pressure. It is postulated that between 20.5 and 24.5 K, neon remains in a meta-stable, supercooled liquid state. When impacting the face of an orifice, liquid neon droplets solidify and accumulate, blocking flow over time. The purpose of this test program was to definitively quantify the phenomena experimentally by obtaining direct visual evidence of orifice clogging by accretion from neon contaminates in the LH2 flow stream, utilizing state of the art imaging technology. Tests were conducted with LH2 flowing in the temperature range of 20.5 to 24.4 K. Additional imaging was also done at LH2 temperatures with no flow to verify clear view through the orifice.

Jurns, John M.; Lekki, John D.

2009-01-01

280

PHYSICAL REVIEW A 83, 052115 (2011) Quantum heating of a parametrically modulated oscillator: Spectral signatures  

E-print Network

from the familiar field-induced Joule-type heat- ing, like the heating of electron systemsPHYSICAL REVIEW A 83, 052115 (2011) Quantum heating of a parametrically modulated oscillator of the nonequidistance of the oscillator quasienergy levels and quantum heating that accompanies relaxation. The heating

Dykman, Mark

281

Integrated Heat Switch/Oxide Sorption Compressor  

NASA Technical Reports Server (NTRS)

Thermally-driven, nonmechanical compressor uses container filled with compressed praseodymium cerium oxide powder (PrCeOx) to provide high-pressure flow of oxygen gas for driving closed-cycle Joule-Thomson-expansion refrigeration unit. Integrated heat switch/oxide sorption compressor has no moving parts except check valves, which control flow of oxygen gas between compressor and closed-cycle Joule-Thomson refrigeration system. Oxygen expelled from sorbent at high pressure by evacuating heat-switch gap and turning on heater.

Bard, Steven

1989-01-01

282

Numerical Modelling of induction heating for two dimensional geometries.  

E-print Network

://dmawww.epfl.ch/rappaz.mosaic/index.html 1 #12;(3) The heat source is the Joule power density which is related to through a non linearNumerical Modelling of induction heating for two dimensional geometries. P. Dreyfuss J. Rappaz Summary We present both a mathematical model and a numerical method for simulating induction heating

Dreyfuss, Pierre

283

COLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY  

E-print Network

out to be a collisionless one rather than the conventional Joule heating dominant for higher pressuresCOLLISIONLESS ELECTRON HEATING IN RF GAS DISCHARGES: I. QUASILINEAR THEORY Yu.M. Aliev1 , I an interest in mechanisms of electron heating and power deposition in the plasma main- tained by radio

Kaganovich, Igor

284

The Scientific Papers of James Prescott Joule 2 Volume Set  

NASA Astrophysics Data System (ADS)

Volume 1: Description of an electro-magnetic engine; Description of an electro-magnetic engine, with experiments; On the use of electro-magnets made of iron wire for the electro-magnetic engine; Investigations in magnetism and electro-magnetism; Investigations in magnetism and electro-magnetism; Description of an electro-magnetic engine; On electro-magnetic forces; On electro-magnetic forces; On electro-magnetic forces; Description of a new electro-magnet; On a new class of magnetic forces; On voltaic apparatus; On the production of heat by voltaic electricity; On the heat evolved by metallic conductors of electricity, and in the cells of a battery during electrolysis; On the electric origin of the heat of combustion; On the electrical origin of chemical heat; On Sir G. C. Haughton's experiments; On the heat evolved during the electrolysis of water; On the calorific effects of magneto-electricity, and on the mechanical value of heat; On the intermittent character of the voltaic current in certain cases of electrolysis; and on the intensities of various voltaic arrangements; On the changes of temperature produced by the rarefaction and condensation of air; On specific heat; On a new method for ascertaining the specific heat of bodies; Note on the employment of electrical currents for ascertaining the specific heat of bodies; On the mechanical equivalent of heat; On the existence of an equivalent relation between heat and the ordinary forms of mechanical power; On the heat disengaged in chemical combinations; On the effects of magnetism upon the dimensions of iron and steel bars; On matter, living force, and heat; On the mechanical equivalent of heat, as determined from the heat evolved by the function of fluids; On the theoretical velocity of sound; Expériences sur l'identité entre le calorique et la force méchanique. Détermination de l'équivalent par la chaleur dégagée pendant la friction du mercure; On shooting-stars; On the mechanical equivalent of heat, and on the constitution of elastic fluids; Some remarks on heat and the constitution of elastic fluids; On the mechanical equivalent of heat; On a remarkable appearance of lightning; On some amalgams; On the air-engine; Account of experiments with a powerful electro-magnet; On the economical production of mechanical effect from chemical forces; An account of some experiments with a large electro-magnet; Introductory research on the induction of magnetism by electric currents; On the fusion of metals by voltaic electricity; Note on Dalton's determination of the expansion of air by heat; On the utilization of the sewage of London and other large towns; Notice of experiments on the heat developed by friction in air; On the intensity of light during the recent solar eclipse; On an improved galvanometer; On the thermo-electricity of ferruginous metals, and on the thermal effects of stretching solid bodies; On the thermal effects of longitudinal compression of solids, with an investigation on the alterations of temperature accompanying changes of pressure in fluids; On some thermo-dynamic properties of solids; On the thermal effects of compressing fluids; On a method of testing the strength of steam-boilers; Experiments on the total heat of steam; Experiments on the passage of air through pipes and apertures in thin plates; On some amalgams; On the probable cause of electric storms; On the surface-condensation of steam; Notice of a compressing air-pump; Note on a mirage at Douglas; On a sensitive barometer; On a sensitive thermometer; Note on the meteor of February 6th, 1818; On a method of hardening steel wires for magnetic needles; On an instrument for showing rapid changes in magnetic declination; Determination of the dynamical equivalent of heat from the thermal effects of electric currents; Observations on the alteration of the freezing-point in thermometers; On a new

Prescott Joule, James

2011-03-01

285

Warm and Hot Stamping of Ultra High Tensile Strength Steel Sheets Using Resistance Heating  

Microsoft Academic Search

A warm and hot stamping process of ultra high tensile strength steel sheets using resistance heating was developed to improve springback and formability. In this process, the decrease in temperature of the sheet before the forming is prevented by directly heating the sheets set into the dies by means of the electrical resistance, the so-called Joule heat. Since the heating

K. Mori; S. Maki; Y. Tanaka

2005-01-01

286

2DN40 -OPGAVEN 2011 1. Ohmic heating at a corner.  

E-print Network

and volume (Ohmic heating) is given by Joule's law J ·E, and leads to the heat-source distribution J ·E = E2DN40 - OPGAVEN 2011 1. Ohmic heating at a corner. Consider the following model for the edge equation for 2 = 0. The heat dissipated as a result of the work done by the field per unit time

Rienstra, Sjoerd W.

287

Quasilinear theory of collisionless electron heating in radio frequency gas discharges  

E-print Network

to be a collisionless one rather than the conven- tional Joule heating dominant for higher pressures. The problemQuasilinear theory of collisionless electron heating in radio frequency gas discharges Yu. M. Aliev heating of rf discharges is treated for characteristic scale lengths of the heating field much shorter

Kaganovich, Igor

288

Binary mixed-refrigerants for steady cooling temperatures between 80 K and 150 K with Joule-Thomson cryocoolers  

NASA Astrophysics Data System (ADS)

Joule-Thomson (JT) cryocoolers operating with pure gases attain vapor-liquid equilibrium in the evaporator and yield a steady cooling temperature which depends solely on the pressure. Mixed gases often substitute the pure gases as the working fluid in order to allow lower pressure ratios and improved coefficient of performance; however, mixed refrigerants are known for their cooling temperature dependence on the ambient temperature and heat load. It is possible to control the cooling temperature via the compressor operating parameters, heating device at the evaporator, bypass ports for the fluid, and more. The present research aims to achieve a steady cooling temperature with mixed refrigerants in a manner similar to pure refrigerants; meaning, having enough phases to leave a single degree of freedom of the fluid thermodynamic state. Thus, by stabilizing the pressure a stable temperature is attained. The current study focuses on binary mixtures since they can be analytically investigated in a more convenient manner relative to multi-component mixtures. Nitrogen-ethane and nitrogen-propane mixtures are considered based on former research conclusions. The present research includes an analytical method for calculating the cooling temperature, a numerical method for calculating the cooling power of the JT cryocooler in order to evaluate whether the cooling temperature is feasible, and experimental data are presented to verify some of the calculated results.

Tzabar, N.

2014-11-01

289

Direct observation of nanoscale Peltier and Joule effects at metal-insulator domain walls in vanadium dioxide nanobeams.  

PubMed

The metal to insulator transition (MIT) of strongly correlated materials is subject to strong lattice coupling, which brings about the unique one-dimensional alignment of metal-insulator (M-I) domains along nanowires or nanobeams. Many studies have investigated the effects of stress on the MIT and hence the phase boundary, but few have directly examined the temperature profile across the metal-insulating interface. Here, we use thermoreflectance microscopy to create two-dimensional temperature maps of single-crystalline VO2 nanobeams under external bias in the phase coexisting regime. We directly observe highly localized alternating Peltier heating and cooling as well as Joule heating concentrated at the M-I domain boundaries, indicating the significance of the domain walls and band offsets. Utilizing the thermoreflectance technique, we are able to elucidate strain accumulation along the nanobeam and distinguish between two insulating phases of VO2 through detection of the opposite polarity of their respective thermoreflectance coefficients. Microelasticity theory was employed to predict favorable domain wall configurations, confirming the monoclinic phase identification. PMID:24735496

Favaloro, Tela; Suh, Joonki; Vermeersch, Bjorn; Liu, Kai; Gu, Yijia; Chen, Long-Qing; Wang, Kevin X; Wu, Junqiao; Shakouri, Ali

2014-05-14

290

Some Joules Are More Precious Than Others: Managing Renewable Energy in the Datacenter  

E-print Network

to data mining. Increasingly, these datacenters use renewable energy from wind tur- bines or solar panels not take full advantage of renewables. For instance, energy-efficient management may batch writes so disks is an electrical joule converted from solar/wind energy. Permission to make digital or hard copies of all or part

Shen, Kai

291

A closed cycle cascade Joule Thomson refrigerator for cooling Josephson junction magnetometers  

NASA Astrophysics Data System (ADS)

A closed cycle cascade Joule Thomson refrigerator designed to cool Josephson Junction magnetometers to liquid helium temperature is being developed. The refrigerator incorporates 4 stages of cooling using the working fluids CF4 and He. The high pressure gases are provided by a small compressor designed for this purpose. The upper stages have been operated and performance will be described.

Tward, E.; Sarwinski, R.

1985-05-01

292

Simultaneous Thermal Imaging of Peltier and Joule Effects B. Vermeersch and A. Shakouri  

E-print Network

. In essence, separation of Peltier and Joule effects relies on their respective linear and quadratic current, such that the excitation current is of the form IDUT = I [ + cos( f t)] , ( ) which creates an oscillating temperature [ ] is commonly used. The main principle is schematically shown in Fig. a. An offset sine wave drives the DUT

293

Probing and Controlling Photothermal Heat Generation in Plasmonic Nanostructures  

E-print Network

Probing and Controlling Photothermal Heat Generation in Plasmonic Nanostructures Zachary J. Coppens, Joule heating associated with optically resonant plasmonic structures is exploited to generate nanoscale by incorporating the diabolo antenna into a plasmonic lens. Using a newly developed thermal microscopy method based

Simaan, Nabil

294

Localized Joule heating produced by ion current focusing through micron-size holes  

Microsoft Academic Search

We provide an experimental demonstration that the focusing of ionic currents in a micron size hole connecting two chambers can produce local temperature increases of up to 100 °C with gradients as large as 1°K mum-1. We find a good agreement between the measured temperature profiles and a finite elements-based numerical calculation. We show how the thermal gradients can be

V. Viasnoff; U. Bockelmann; A. Meller; H. Isambert; L. Laufer; Y. Tsori

2010-01-01

295

Physical modeling of a dual-electrode-pair, joule heated glass melter  

Microsoft Academic Search

The purpose of this study was to evaluate various dual-electrode-pair (DEP) melter configurations which feature independently power controlled upper and lower electrode pairs. The effects of upper to lower electrode spacing and electrode power ratio on the molten glass temperature and electric field were examined using a laboratory scale model. These influences are of interest because large temperature gradients in

J. R. Skarda; C. R. Reid

1985-01-01

296

Localized Joule heating produced by ion current focusing through micron-size holes  

NASA Astrophysics Data System (ADS)

We provide an experimental demonstration that the focusing of ionic currents in a micron size hole connecting two chambers can produce local temperature increases of up to 100 °C with gradients as large as 1°K ?m-1. We find a good agreement between the measured temperature profiles and a finite elements-based numerical calculation. We show how the thermal gradients can be used to measure the full melting profile of DNA duplexes within a region of 40 ?m. The possibility to produce even larger gradients using submicron pores is discussed.

Viasnoff, V.; Bockelmann, U.; Meller, A.; Isambert, H.; Laufer, L.; Tsori, Y.

2010-04-01

297

Discretization of the Joule heating term for plasma discharge fluid models in unstructured meshes  

Microsoft Academic Search

The fluid (continuum) approach is commonly used for simulation of plasma phenomena in electrical discharges at moderate to high pressures (>10’smTorr). The description comprises governing equations for charged and neutral species transport and energy equations for electrons and the heavy species, coupled to equations for the electromagnetic fields. The coupling of energy from the electrostatic field to the plasma species

T. Deconinck; S. Mahadevan; L. L. Raja

2009-01-01

298

Concentration enhancement of sample solutes in a sudden expansion microchannel with Joule heating  

Microsoft Academic Search

Microfluidic concentration of sample solutes is achieved by using temperature gradient focusing (TGF) in a microchannel with a step change in cross-section. A mathematical model is developed to describe the complex TGF processes. Scaling analysis is conducted to estimate time scales so as to simplify the proposed mathematical model. Numerical computations are performed to obtain the temperature, velocity and sample

Zhengwei Ge; Chun Yang; Gongyue Tang

2010-01-01

299

Joule heating and high frequency nonlinear effects in the surface impedance of high Tc superconductors  

E-print Network

Superconductor (HTSC) films are suitable candidates for the improve- ment of microwave receiver performance because of their low surface resistance.1­4 The sur- face impedance of HTSC materials presents a strong and filters and a downward shift of the resonant frequency of the former.5­7 The surface impedance of HTSC has

Boyer, Edmond

300

Investigations on Joule heating applications by multiphysical continuum simulations in nanoscale systems.  

E-print Network

??This work furthers the overall understanding of a 3?-measurement, by considering previously unexamined macroscopic influence factors within measurement by Finite Element simulations (FES). Moreover, new… (more)

Feuchter, Manuel Klaus Ludwig

2014-01-01

301

Auroral Energy Input From Energetic Electrons and Joule Heating at Chatanika  

Microsoft Academic Search

With the incoherent scatter radar at Chatanika, Alaska, a wide variety of measurements can be made related to the ionosphere, magnetosphere, and neutral atmosphere. A significant parameter is the amount of energy transferred from the magnetosphere into the ionosphere and neutral atmosphere during periods of auroral activity. In this report we examine a procedure whereby the incident energy flux of

Vincent B. Wickwar; Murray J. Baron; Robert D. Sears

1975-01-01

302

Localized Joule heating produced by ion current focusing through micron-size holes  

E-print Network

We provide an experimental demonstration that the focusing of ionic currents in a micron size hole connecting two chambers can produce local temperature increases of up to $100^\\circ$ C with gradients as large as $1^\\circ$ K$\\mu m^{-1}$. We find a good agreement between the measured temperature profiles and a finite elements-based numerical calculation. We show how the thermal gradients can be used to measure the full melting profile of DNA duplexes within a region of 40 $\\mu$m. The possibility to produce even larger gradients using sub-micron pores is discussed.

V. Viasnoff; U. Bockelmann; A. Meller; H. Isambert; L. Laufer; Y. Tsori

2010-04-27

303

Joule heating in the mesosphere and thermosphere during the July 13, 1982, solar proton event  

Microsoft Academic Search

The solar proton event of July 13, 1982 produced considerable ionization in the polar-cap mesosphere. Energetic solar proton fluxes were measured by the NOAA-6 satellite. The DE-2 satellite measured the low-energy electrons, the ion drift velocity, and other atmospheric and ionospheric properties during the event in the region of the measured maximum electric field (189 mV\\/m at 2215 UT near

R. G. Roble; B. A. Emery; R. R. Garcia; T. L. Killeen; P. B. Hays; G. C. Reid; S. Solomon; D. S. Evans; N. W. Spencer; W.B. Hanson; D. J. Winningham; L. H. Brace

1987-01-01

304

Role of solar wind dynamic pressure in driving ionospheric Joule heating  

Microsoft Academic Search

We investigate the role of the solar wind dynamic pressure on the ionospheric dynamics both observationally and using a global MHD simulation. Using ACE solar wind observations we carry out a statistical superposed epoch analysis, in which we determine the ionospheric response, as characterized by the AE index, to solar wind pressure pulses identified from the ACE solar wind data.

M. Palmroth; T. I. Pulkkinen; P. Janhunen; D. J. McComas; C. W. Smith; H. E. J. Koskinen

2004-01-01

305

Electric fields, Joule and particle heating in the high latitude thermosphere  

Microsoft Academic Search

The author points out some difficulties involved in interpreting the motion of ionospheric irregularities and auroral forms in terms of magnetospheric convection. One main source of error in such interpretations is the existence of local small-scale electric fields in the lower ionosphere. Incoherent scatter radar is, however, able to derive average ion drift values, with localized effects removed, that can

A. Brekke

1976-01-01

306

Self-Heating Effects in GaN/AlGaN Heterostructure Field-Effect Transistors and Device Structure Optimization  

E-print Network

for similar devices [8]. Since Joule heating is the dominant heating effect for a given device, one can writeSelf-Heating Effects in GaN/AlGaN Heterostructure Field-Effect Transistors and Device Structure time, performance of these devices has been limited by self-heating and other problems associated

307

An in-depth Analysis of Space Heating Energy Use in Office Buildings  

E-print Network

LBNL-5732E An in-depth Analysis of Space Heating Energy Use in Office Buildings Author(s), Hung than 7 trillion Joules of site energy annually [USDOE]. Analyzing building space heating performance driving factors to space heating energy use to support the design and operation of low energy buildings

308

Airdensitydependent model for analysis of air heating associated with streamers, leaders, and transient luminous events  

E-print Network

predicted on the basis of similarity laws for Joule heating. This acceleration is attributed to a strongAirdensitydependent model for analysis of air heating associated with streamers, leaders and chemical kinetics involved in heating of air in streamer channels for a given air density N under

Pasko, Victor

309

Rapid synthesis of carbon nanotubes via inductive heating Brian D. Sosnowchika  

E-print Network

is the depth of penetration from the substrate surface where 86% of the Joule heating occurs, as calculated byRapid synthesis of carbon nanotubes via inductive heating Brian D. Sosnowchika and Liwei Lin an inductive heating system. Substrates of either heavily doped silicon or nickel-coated, lightly doped silicon

Lin, Liwei

310

Correlation between suprathermal electron bursts, broadband extremely low frequency waves, and local ion heating in the  

E-print Network

that three main possible mechanisms could drive ion outflow: frictional (Joule) ion heating, thermal electron, and local ion heating in the midaltitude cleft//low-latitude boundary layer observed by Cluster Y. V+ and H+ ion heating and with localized extra low frequency (ELF) (1­10 Hz) magnetic field wave power

Lotko, William

311

Acquisition and correlation of cryogenic nitrogen mass flow data through a multiple orifice Joule-Thomson device  

NASA Technical Reports Server (NTRS)

Liquid nitrogen mass flow rate, pressure drop, and temperature drop data were obtained for a series of multiple orifice Joule-Thomson devices, known as Visco Jets, over a wide range of flow resistance. The test rig used to acquire the data was designed to minimize heat transfer so that fluid expansion through the Visco Jets would be isenthalpic. The data include a range of fluid inlet pressures from 30 to 60 psia, fluid inlet temperatures from 118 to 164 R, outlet pressures from 2.8 to 55.8 psia, outlet temperatures from 117 to 162 R and flow rate from 0.04 to 4.0 lbm/hr of nitrogen. A flow rate equation supplied by the manufacturer was found to accurately predict single-phase (noncavitating) liquid nitrogen flow through the Visco Jets. For cavitating flow, the manufacturer's equation was found to be inaccurate. Greatly improved results were achieved with a modified version of the single-phase equation. The modification consists of a multiplication factor to the manufacturer's equation equal to one minus the downstream quality on an isenthalpic expansion of the fluid across the Visco Jet. For a range of flow resistances represented by Visco Jet Lohm ratings between 17,600 and 80,000, 100 percent of the single-phase data and 85 percent of the two-phase data fall within + or - 10 percent of predicted values.

Papell, S. Stephen; Saiyed, Naseem H.; Nyland, Ted W.

1990-01-01

312

Investigation of neon-nitrogen mixed refrigerant Joule-Thomson cryocooler operating below 70 K with precooling at 100 K  

NASA Astrophysics Data System (ADS)

There has been two-stage mixed refrigerant (MR) Joule-Thomson (JT) refrigeration cycle suggested for cooling high temperature superconductor (HTS) electric power cable below 70 K. As the continuation effort of realizing the actual system, we fabricated and tested a small scale neon and nitrogen MR JT cryocooler to investigate the refrigeration characteristics and performance. The compression system of the refrigeration circuit was accomplished by modifying commercially available air-conditioning rotary compressors. Compressors stably operated at the maximum compression ratio of 31 when the suction pressure was 77 kPa. The achieved lowest temperature was 63.6 K when the heating load was 35.9 W. The measured Carnot efficiency of the present system was 6.5% which was lower than that of the designed goal of 17.4%. The low efficiency of compressor (34.5%), and the pressure drop at the compressor suction were the main reasons for this efficiency degradation. The feasibility and usefulness of neon and nitrogen MR JT refrigeration cycle was validated that the achieved minimum temperature was 63.6 K even though the pressure after the expansion was maintained by 130 kPa. The comparison between the measurement and calculation showed that each stream temperature of refrigeration cycle were predictable within 3% error by Peng-Robinson equation of state (EOS).

Lee, Jisung; Oh, Haejin; Jeong, Sangkwon

2014-05-01

313

Quantum Joule-Thomson effect in a saturated homogeneous Bose gas.  

PubMed

We study the thermodynamics of Bose-Einstein condensation in a weakly interacting quasihomogeneous atomic gas, prepared in an optical-box trap. We characterize the critical point for condensation and observe saturation of the thermal component in a partially condensed cloud, in agreement with Einstein's textbook picture of a purely statistical phase transition. Finally, we observe the quantum Joule-Thomson effect, namely isoenthalpic cooling of an (essentially) ideal gas. In our experiments this cooling occurs spontaneously, due to energy-independent collisions with the background gas in the vacuum chamber. We extract a Joule-Thomson coefficient ?JT>10(9)??K/bar, about 10 orders of magnitude larger than observed in classical gases. PMID:24580421

Schmidutz, Tobias F; Gotlibovych, Igor; Gaunt, Alexander L; Smith, Robert P; Navon, Nir; Hadzibabic, Zoran

2014-01-31

314

The development of a proff of principle superfluid Joule-Thomson refrigerator for cooling below 1 Kelvin  

E-print Network

A new type of sub-Kelvin refrigerator, the superfluid Joule-Thomson refrigerator, has been developed and its performance has been experimentally verified. This refrigerator uses a liquid superfluid mixture of He and 4He ...

Miller, Franklin K., 1970-

2005-01-01

315

Joule-assisted silicidation for short-channel silicon nanowire devices.  

PubMed

We report on a technique enabling electrical control of the contact silicidation process in silicon nanowire devices. Undoped silicon nanowires were contacted by pairs of nickel electrodes, and each contact was selectively silicided by means of the Joule effect. By a real-time monitoring of the nanowire electrical resistance during the contact silicidation process we were able to fabricate nickel-silicide/silicon/nickel-silicide devices with controlled silicon channel length down to 8 nm. PMID:21815658

Mongillo, Massimo; Spathis, Panayotis; Katsaros, Georgios; Gentile, Pascal; Sanquer, Marc; De Franceschi, Silvano

2011-09-27

316

Optimization of the working fluid in a Joule–Thomson cold stage  

Microsoft Academic Search

Vibration-free miniature Joule–Thomson (JT) coolers are of interest for cooling a wide variety of devices, including low-noise amplifiers, semiconducting and superconducting electronics, and small optical detectors used in space applications. For cooling such devices, coolers are needed which have operating temperatures within a wide temperature range of 2–250K. In this paper, the optimization of the working fluid in JT cold

J. H. Derking; H. J. M. ter Brake; A. Sirbi; M. Linder; H. Rogalla

2009-01-01

317

Hampson’s type cryocoolers with distributed Joule-Thomson effect for mixed refrigerants closed cycle  

NASA Astrophysics Data System (ADS)

Most previous studies on Joule-Thomson cryocoolers of mixed refrigerants in a closed cycle focus on the Linde kind recuperator. The present study focuses on four constructions of Hampson’s kind miniature Joule-Thomson cryocoolers based on finned capillary tubes. The frictional pressure drop along the tubes plays the role of distributed Joule-Thomson expansion so that an additional orifice or any throttle at the cold end is eliminated. The high pressure tube is a throttle and a channel of recuperation at the same time. These coolers are tested within two closed cycle systems of different compressors and different compositions of mixed coolants. All tests were driven by the same level of discharge pressure (2.9 MPa) while the associated suction pressures and the associated reached temperatures are dependent on each particular cryocooler and on the closed cycle system. The mixture of higher specific cooling capacity cannot reach temperatures below 80 K when driven by the smaller compressor. The other mixture of lower specific cooling capacity driven by the larger compressor reaches lower temperatures. The examined parameters are the cooldown period and the reachable temperatures by each cryocooler.

Maytal, Ben-Zion

2014-05-01

318

Solution to the 1-D unsteady heat conduction equation with internal Joule heat generation for thermoelectric devices  

Microsoft Academic Search

Thermoelectric devices are semiconductor devices which are capable of either generating a voltage when placed in between a temperature gradient, exploiting the Seebeck effect, or producing a temperature gradient when powered by electricity, exploiting the Peltier effect. The devices are usually employed in environments with time-varying temperature differences and input\\/output powers. Therefore it becomes important to understand the behaviour of

A. Montecucco; J. R. Buckle; A. R. Knox

319

AN EXPERIMENTAL STUDY AND NUMERICAL SIMULATION OF TWO-PHASE FLOW OF CRYOGENIC FLUIDS THROUGH MICROCHANNEL HEAT EXCHANGER  

Microsoft Academic Search

The design, fabrication, testing and analysis of a microchannel heat exchanger, a key component for a microminiature Joule-Thomson Cryogenic Refrigerator is described. Results show that the heat exchanger can be fabricated efficiently and economically with the existing manufacturing technology. The heat exchanger was tested to be mechanically robust and durable under high pressure operating condition. \\

W. W. Yuen; I. C. Hsu

320

hal-00252040,version1-12Feb2008 Near-field induction heating of metallic nanoparticles due to infrared magnetic  

E-print Network

hal-00252040,version1-12Feb2008 Near-field induction heating of metallic nanoparticles due mechanism is near-field induction heating, due to Joule dissipation of eddy currents in the particle.ecp.fr We revisit the electromagnetic heat transfer between a metallic nanoparticle and a metallic semi

Paris-Sud XI, Université de

321

Self-heating in normal metals and superconductors  

Microsoft Academic Search

This review is devoted to the physics of current-carrying superconductors and normal metals having two or more stable states sustained by Joule self-heating. The creation, propagation, and localization of electrothermal domains and switching waves leading to the transition from one stable state to another in uniform and nonuniform samples are treated in detail. The connection between thermal bistability and hysteresis,

A. V. Gurevich; R. G. Mints

1987-01-01

322

One-Joule-per-Pulse Q-Switched 2-micron Solid State Laser  

NASA Technical Reports Server (NTRS)

Q-switched output of 1.1 J per pulse at 2-micron wavelength has been achieved in a diode pumped Ho:Tm:LuLF laser using a side-pumped rod configuration in a Master-Oscillator-Power-Amplifier (MOPA) architecture. This is the first time that a 2-micron laser has broken the Joule per pulse barrier for Q-switched operation. The total system efficiency reaches 5% and 6.2% for single and double pulse operation, respectively. The system produces excellent 1.4 times of transform limited beam quality.

Yu, Jirong; Trieu, Bo C.; Modlin, Ed A.; Singh, Upendra N.; Kavaya, Michael J.; Chen, Songsheng; Bai, Yingxin; Petzar, Pual J.; Petros, Mulugeta

2005-01-01

323

Investigation of two-phase heat transfer coefficients of argon-freon cryogenic mixed refrigerants  

NASA Astrophysics Data System (ADS)

Mixed refrigerant Joule Thomson refrigerators are widely used in various kinds of cryogenic systems these days. Although heat transfer coefficient estimation for a multi-phase and multi-component fluid in the cryogenic temperature range is necessarily required in the heat exchanger design of mixed refrigerant Joule Thomson refrigerators, it has been rarely discussed so far. In this paper, condensation and evaporation heat transfer coefficients of argon-freon mixed refrigerant are measured in a microchannel heat exchanger. A Printed Circuit Heat Exchanger (PCHE) with 340 ?m hydraulic diameter has been developed as a compact microchannel heat exchanger and utilized in the experiment. Several two-phase heat transfer coefficient correlations are examined to discuss the experimental measurement results. The result of this paper shows that cryogenic two-phase mixed refrigerant heat transfer coefficients can be estimated by conventional two-phase heat transfer coefficient correlations.

Baek, Seungwhan; Lee, Cheonkyu; Jeong, Sangkwon

2014-11-01

324

Evaluation of the invasion heat for the HTS current lead using YBCO  

Microsoft Academic Search

Current leads using high-TC superconductors (HTS current leads) are one of cryogenic key devices to assemble compact superconducting magnets such as applied for maglev trains etc. It is essential to evaluate effective thermal conductance through a HTS current lead package together with evaluating Joule heat and critical current for efficient design that has high current capacity and low heat invasion.

R. Endoh; H. Kato; T. Izumi; Y. Shiohara

2003-01-01

325

Heterogeneous nanometer-scale Joule and Peltier effects in sub-25 nm thin phase change memory devices  

NASA Astrophysics Data System (ADS)

We measure heterogeneous power dissipation in phase change memory (PCM) films of 11 and 22 nm thin Ge2Sb2Te5 (GST) by scanning Joule expansion microscopy (SJEM), with sub-50 nm spatial and ˜0.2 K temperature resolution. The heterogeneous Joule and Peltier effects are explained using a finite element analysis (FEA) model with a mixture of hexagonal close-packed and face-centered cubic GST phases. Transfer length method measurements and effective media theory calculations yield the GST resistivity, GST-TiW contact resistivity, and crystal fraction of the GST films at different annealing temperatures. Further comparison of SJEM measurements and FEA modeling also predicts the thermopower of thin GST films. These measurements of nanometer-scale Joule, thermoelectric, and interface effects in PCM films could lead to energy-efficient designs of highly scaled PCM technology.

Grosse, Kyle L.; Pop, Eric; King, William P.

2014-09-01

326

Measurements of Plasma Density in a Fast and Compact Plasma Focus Operating at Hundreds of Joules  

SciTech Connect

It is known that there are plasma parameters that remain relatively constant for plasma focus facilities operating in a wide range of de energy, from 1kJ to 1MJ, such as: electron density, temperature and plasma energy density. Particularly the electron density is of the order of 1025m-3. Recently the experimental studies in plasma focus has been extended to devices operating under 1kJ, in the range of hundreds and tens of joules. In this work an optical refractive system was implemented in order to measure the electron density in a plasma focus devices of hundred of joules, PF-400J (880 nF, 30 kV, 120 kA, 400 J, 300 ns time to peak current, dI/dt{approx}4x1011 A/s. The plasma discharge was synchronized with a pulsed Nd-YAG laser ({approx}6ns FWHM at 532nm) in order to obtain optical diagnostics as interferometry and Schlieren. An electron density of (0.9{+-}0.25)x1025m-3 was obtained at the axis of the plasma column close to the pinch time. This value is of the same order that the obtained in devices oparating in the energy range of 1kJ to 1MJ.

Pavez, Cristian [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Universidad de Concepcion, Facultad de Ciencias, Departamento de Fisica, Concepcion (Chile); Silva, Patricio; Moreno, Jose; Soto, Leopoldo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile)

2006-12-04

327

2DN40 -OPGAVEN 2012 1. Ohmic heating at a corner.  

E-print Network

and volume (Ohmic heating) is given by Joule's law J ·E, and leads to the heat-source distribution J ·E = E2DN40 - OPGAVEN 2012 1. Ohmic heating at a corner. We consider the following model for the edge equation for 2 = 0. (1) The heat dissipated as a result of the work done by the field per unit time

Rienstra, Sjoerd W.

328

Influence of the Thomson effect on the pulse heating of high-current electrical contacts  

NASA Astrophysics Data System (ADS)

Pulse heating of high-current contacts is notable for the presence of considerable temperature gradients in the contact area, which cause the Thomson effect—the appearance of thermoelectric currents. The amount of this effect against conventional Joule heat release is quantitatively estimated. Pulse heating of electrical contacts is numerically simulated with the use of the Comsol program package. It is demonstrated that thermoelectric currents make a negligible contribution to heating in the case of copper contacts.

Merkushev, A. G.; Pavleino, M. A.; Pavleino, O. M.; Pavlov, V. A.

2014-09-01

329

Flow boiling heat transfer coefficients at cryogenic temperatures for multi-component refrigerant mixtures of nitrogen-hydrocarbons  

NASA Astrophysics Data System (ADS)

The recuperative heat exchanger governs the overall performance of the mixed refrigerant Joule-Thomson cryocooler. In these heat exchangers, the non-azeotropic refrigerant mixture of nitrogen-hydrocarbons undergoes boiling and condensation simultaneously at cryogenic temperature. Hence, the design of such heat exchanger is crucial. However, due to lack of empirical correlations to predict two-phase heat transfer coefficients of multi-component mixtures at low temperature, the design of such heat exchanger is difficult.

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

330

A high- Tc SQUID-based sensor head cooled by a Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

The goal of the so-called FHARMON project is to develop a high- Tc SQUID-based magnetometer system for the measurement of fetal heart activity in standard clinical environments. To lower the threshold for the application of this fetal heart monitor, it should be simple to operate. It is, therefore, advantageous to replace the liquid cryogen bath by a closed-cycle refrigerator. For this purpose, we selected a mixed-gas Joule-Thomson cooler; the APD Cryotiger ©. Because of its magnetic interference, the compressor of this closed-cycle cooler will be placed at a distance of ?2 m from the actual sensor, which is an axial second order gradiometer. The gradiometer is formed by three magnetometers placed on an alumina cylinder, which is connected to the cold head of the cooler. This paper describes the sensor head in detail and reports on test experiments.

Rijpma, A. P.; ter Brake, H. J. M.; de Vries, E.; Nijhof, N.; Holland, H. J.; Rogalla, H.

2002-08-01

331

Numerical simulation of flare energy build-up and release via Joule dissipation. [solar MHD model  

NASA Technical Reports Server (NTRS)

A new numerical MHD model is developed to study the evolution of an active region due to photospheric converging motion, which leads to magnetic-energy buildup in the form of electric current. Because this new MHD model has incorporated finite conductivity, the energy conversion occurs from magnetic mode to thermal mode through Joule dissipation. In order to test the causality relationship between the occurrence of flare and photospheric motion, a multiple-pole configuration with neutral point is used. Using these results it is found that in addition to the converging motion, the initial magnetic-field configuration and the redistribution of the magnetic flux at photospheric level enhance the possibility for the development of a flare.

Wu, S. T.; Bao, J. J.; Wang, J. F.

1986-01-01

332

Soft X-Ray Emission and Charged Particles Beams from a Plasma Focus of Hundreds Joules  

SciTech Connect

In a new stage of characterization of our plasma focus devices of hundred and tens of joules (PF-400J and PF-50J), preliminary series of measurements on soft X-ray and ion beams have been performed in the device PF-400J (176-539 J, 880 nF, T/4 {approx}300 ns). The device was operated in hydrogen to 7 mbar of pressure . The temporal and spatial X-ray characteristics are investigated by means filtered PIN diodes and a multipinhole camera. Graphite collectors, operating in the bias ion collector mode, are used to estimate the characteristic ion energy using the time flight across the probe array. The time of the ion beam emission to be correlated with plasma emission events associated with the soft X-ray pulses detected by the probes. Temporal correlations between soft X-ray signals and ion beams are performed.

Silva, Patricio; Moreno, Jose; Soto, Leopoldo [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Pavez, Cristian [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Universidad de Concepcion, Facultad de Ciencias, Departamento de Fisica, Concepcion (Chile); Arancibia, Jaime [Universidad de Chile, Facultad de Ciencias, Departamento de Fisica, Santiago (Chile)

2006-12-04

333

Heat dissipation from suspended self-heated nanowires: gas sensor prospective.  

PubMed

The strong temperature dependence of the electrical conductivity in semiconductors was employed for gas and pressure sensing with a self-heated Si nanowire resistor. The electrical conductivity in such a device depends on heat dissipation and partitioning inside the device and was studied comparatively for suspended and supported device architectures. The appearance of the exhaustion region in the temperature-dependent resistivity of a Joule-heated nanowire was used as a temperature marker for implementation of the quasi-constant temperature operation mode. At low pressures, the sensor is idle due to dominant heat dissipation from the nanowire to the substrate and/or electrodes. Above ca. 10 Torr the sensitivity to gases has a strong dependence on pressure as well as on the type of gas and is determined by conductive heat transfer between the nanowire surface and ambient. This implies that, in contrast to macroscopic devices, the heat dissipation via the convection mechanism does not contribute significantly to the heat transfer from the self-heated nanowire. The thermal sensitivity of the sensor to reactive gases depends on the effectiveness of the particular endothermic/exothermic reaction at the surface of the nanowire and was explored for the case of acetone-air mixture. The strong coupling of the electrical and thermal properties in the individual Joule-heated semiconducting nanowire allows fabrication of power-efficient multi-parametric nanoscopic gas/pressure sensors that are analogs of Pirani and pellistor type detectors. PMID:24113219

Zhang, Jie; Strelcov, Evgheni; Kolmakov, Andrei

2013-11-01

334

Heat dissipation from suspended self-heated nanowires: gas sensor prospective  

NASA Astrophysics Data System (ADS)

The strong temperature dependence of the electrical conductivity in semiconductors was employed for gas and pressure sensing with a self-heated Si nanowire resistor. The electrical conductivity in such a device depends on heat dissipation and partitioning inside the device and was studied comparatively for suspended and supported device architectures. The appearance of the exhaustion region in the temperature-dependent resistivity of a Joule-heated nanowire was used as a temperature marker for implementation of the quasi-constant temperature operation mode. At low pressures, the sensor is idle due to dominant heat dissipation from the nanowire to the substrate and/or electrodes. Above ca. 10 Torr the sensitivity to gases has a strong dependence on pressure as well as on the type of gas and is determined by conductive heat transfer between the nanowire surface and ambient. This implies that, in contrast to macroscopic devices, the heat dissipation via the convection mechanism does not contribute significantly to the heat transfer from the self-heated nanowire. The thermal sensitivity of the sensor to reactive gases depends on the effectiveness of the particular endothermic/exothermic reaction at the surface of the nanowire and was explored for the case of acetone-air mixture. The strong coupling of the electrical and thermal properties in the individual Joule-heated semiconducting nanowire allows fabrication of power-efficient multi-parametric nanoscopic gas/pressure sensors that are analogs of Pirani and pellistor type detectors.

Zhang, Jie; Strelcov, Evgheni; Kolmakov, Andrei

2013-11-01

335

Heat Transport in Graphene  

NASA Astrophysics Data System (ADS)

We fabricated suspended graphene devices and measured their thermal conductivity, ?, as a function of both temperature, T, and charge carrier density, n. Heat transport is a powerful tool to obtain information about both the phononic and electronic properties of graphene. Recent heat transport experiments in graphene have shown a high ?, but a detailed mapping of graphene's heat conductivity versus T and n is not yet available. The measurement technique we developed is a two-point method which uses graphene as its own heat source (Joule heating) and thermometer (resistivity). We report ? at temperatures ranging from 6 to 350 Kelvin, and at charge carrier densities close to the Dirac point up to about 1.5 x10^11/cm^2, in graphene crystals whose length varies from 250 nm up to one micron. We observed that the thermal conductivity increases by over two orders of magnitude over the temperature range, and that it also increases with the crystal's length. ? can be tuned by an order of magnitude with gate voltage, opening the possibility of creating room temperature heat transistors.

Yigen, Serap; Tayari, Vahid; Island, Joshua O.; Porter, James; Champagne, A. R.

2012-02-01

336

Heat conduction in a symmetric body subjected to a current flow of symmetric input and output  

Microsoft Academic Search

Steady heat conduction in symmetrical electro-thermal problems is analyzed under the influence of a steady direct current passing through symmetrical regions of the boundary. In the present approach, solution is obtained by dividing the temperature field of the electro-thermal problem into two fields—one is related to the heat conduction problem without Joule heating and the other corresponds to a symmetric

M. Saka; Y. X. Sun; S. Reaz Ahmed

2009-01-01

337

Visco Jet Joule-Thomson Device Characterization Tests in Liquid Methane  

NASA Technical Reports Server (NTRS)

Joule-Thomson (J-T) devices have been identified as critical components for Thermodynamic Vent Systems (TVS) planned for future space exploration missions. Lee Visco Jets (The Lee Company) (Ref. 4) are one type of J-T device that may be used for LCH4 propellant systems. Visco Jets have been previously tested and characterized in LN2 and LH2 (Refs. 6 and 7), but have not been characterized in LOX or LCH4. Previous Visco Jet tests with LH2 resulted in clogging of the Visco Jet orifice under certain conditions. It has been postulated that this clogging was due to the presence of neon impurities in the LH2 that solidified in the orifices. Visco Jets therefore require testing in LCH4 to verify that they will not clog under normal operating conditions. This report describes a series of tests that were performed at the NASA Glenn Research Center to determine if Visco Jets would clog under normal operating conditions with LCH4 propellant. Test results from this program indicate that no decrease in flow rate was observed for the Visco Jets tested, and that current equation used for predicting flow rate appears to under-predict actual flow at high Lohm ratings.

Jurns, John M.

2009-01-01

338

Properties of Gas Mixtures and Their Use in Mixed-Refrigerant Joule-Thomson Refrigerators  

NASA Astrophysics Data System (ADS)

The Joule-Thomson (J-T) effect has been widely used for achieving low temperatures. In the past few years, much progress has been made in better understanding the working mechanism of the refrigeration method and in developing prototypes for different applications. In this talk, there are three aspects of our research work to be discussed. First, some special thermal properties of the mixtures for achieving liquid nitrogen temperature range will be presented. Secondly, some important conclusions from the optimization of various mixed-refrigerant J-T cycles such as a simple J-T cycle and an auto-cascade mixed-refrigerant J-T cycle will be presented. Moreover, an auto-cascade, mixed-refrigerant J-T refrigerator with a special mixture capable of achieving about 50K will be mentioned. Finally, various prototypes based on the mixed-refrigerant refrigeration technology will be described. These applications include miniature J-T cryocoolers for cooling infrared detectors and high-temperature superconducting devices, cryosurgical knife for medical treatment, low-temperature refrigerators for biological storage and so forth. The on-going research work and unanswered questions for this technology will be also discussed.

Luo, E.; Gong, M.; Wu, J.; Zhou, Y.

2004-06-01

339

Investigation of pressure drop in capillary tube for mixed refrigerant Joule-Thomson cryocooler  

NASA Astrophysics Data System (ADS)

A capillary tube is commonly used in small capacity refrigeration and air-conditioning systems. It is also a preferred expansion device in mixed refrigerant Joule-Thomson (MR J-T) cryocoolers, since it is inexpensive and simple in configuration. However, the flow inside a capillary tube is complex, since flashing process that occurs in case of refrigeration and air-conditioning systems is metastable. A mixture of refrigerants such as nitrogen, methane, ethane, propane and iso-butane expands below its inversion temperature in the capillary tube of MR J-T cryocooler and reaches cryogenic temperature. The mass flow rate of refrigerant mixture circulating through capillary tube depends on the pressure difference across it. There are many empirical correlations which predict pressure drop across the capillary tube. However, they have not been tested for refrigerant mixtures and for operating conditions of the cryocooler. The present paper assesses the existing empirical correlations for predicting overall pressure drop across the capillary tube for the MR J-T cryocooler. The empirical correlations refer to homogeneous as well as separated flow models. Experiments are carried out to measure the overall pressure drop across the capillary tube for the cooler. Three different compositions of refrigerant mixture are used to study the pressure drop variations. The predicted overall pressure drop across the capillary tube is compared with the experimentally obtained value. The predictions obtained using homogeneous model show better match with the experimental results compared to separated flow models.

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-01-01

340

Experimental and numerical investigation into the joule heating effect for electrokinetically driven microfluidic chips utilizing total internal reflection fluorescence microscopy  

Microsoft Academic Search

This paper presents a detection scheme for analyzing the temperature distribution nearby the channel wall in a microfluidic\\u000a chip utilizing a temperature-dependent fluorescence dye. An advanced optical microscope system—total internal reflection fluorescence\\u000a microscope (TIRFM) is used for measuring the temperature distribution on the channel wall at the point of electroosmotic flow\\u000a in an electrokinetically driven microfluidic chip. In order to

Lung-Ming Fu; Jing-Hui Wang; Wen-Bo Luo; Che-Hsin Lin

2009-01-01

341

The responses of the thermospheric neutral wind circulation and temperature to intense Joule heating during geomagnetic storms  

Microsoft Academic Search

The Center for Integrated Space weather Modeling (CISM) suite of models was run recently to perform an end-to-end simulation of the solar-terrestrial environment. The Coupled Magnetosphere-Ionosphere Model (CMIT) is one of the models used in this run. The CMIT has two components: the LFM global magnetosphere model and the Thermosphere-Ionosphere Nested Grid (TING) model. The CMIT was driven by the

W. Wang; A. G. Burns; T. L. Killeen; M. Wiltberger; S. C. Solomon

2004-01-01

342

Observation of Joule Heating-Assisted Electromigration Failure Mechanisms for Dual Damascene Cu/SiO? Interconnects  

E-print Network

Failure mechanisms observed in electromigration (EM) stressed dual damascene Cu/SiO? interconnects trees were studied and simulated. Failure sites with â??melt patch’ or â??crater’ are common for test structures in the top ...

Chang, Choon Wai

343

Effects of thermophoresis particle deposition and of the thermal conductivity in a porous plate with dissipative heat and mass transfer  

Microsoft Academic Search

Network simulation method (NSM) is used to solve the laminar heat and mass transfer of an electrically-conducting, heat generating\\/absorbing\\u000a fluid past a perforated horizontal surface in the presence of viscous and Joule heating problem. The governing partial differential\\u000a equations are non-dimensionalized and transformed into a system of nonlinear ordinary differential similarity equations, in\\u000a a single independent variable, ?. The resulting

Joaquín Zueco; O. Anwar Bég; L. M. López-Ochoa

2011-01-01

344

Heat Transfer Characteristics of Mixed Electroosmotic and Pressure Driven Micro-Flows  

NASA Astrophysics Data System (ADS)

We analyze heat transfer characteristics of steady electroosmotic flows with an arbitrary pressure gradient in two-dimensional straight microchannels considering the effects of Joule heating in electroosmotic pumping. Both the temperature distribution and local Nusselt number are mathematically derived in this study. The thermal analysis takes into consideration of the interaction among advective, diffusive, and Joule heating terms to obtain the thermally developing behavior. Unlike macro-scale pipes, axial conduction in micro-scale cannot be negligible, and the governing energy equation is not separable. Thus, a method that considers an extended Graetz problem is introduced. Analytical results show that the Nusselt number of pure electrooosmotic flow is higher than that of plane Poiseulle flow. Moreover, when the electroosmotic flow and pressure driven flow coexist, it is found that adverse pressure gradient to the electroosmotic flow makes the thermal entrance length smaller and the heat transfer ability stronger than pure electroosmotic flow case.

Horiuchi, Keisuke; Dutta, Prashanta

345

Enhanced heat transfer computations for internally cooled cable superconductor  

SciTech Connect

Superconducting magnets are built with conductors that are pool bath cooled, internally cooled with the superconductor cabled and contained within a conduit, or conduction cooled. The first two embody superconductors in direct contact with liquid helium. Practical designs of internally cooled cable superconductor (ICCS) are not cryostable. Such superconductors have shown multiple regions of stability and instability. A computational method of adjusting the heat transfer coefficient of a one dimensional system of equations to enhance joule heat removal, primarily in the central region of a pulse heated model of ICCS, has been used to attempt simulation of the multiple stability/instability experiment.

Rogers, J.D.

1985-01-01

346

Dimensional Analysis of Thermoelectric Modules Under Constant Heat Flux  

NASA Astrophysics Data System (ADS)

Thermoelectric power generation is examined in the case of radiative heating. A constant heat flux is assumed in addition to consideration of the Seebeck effect, Peltier effect, and Joule heating with temperature-dependent material properties. Numerical evaluations are conducted using a combination of the finite-volume method and an original simultaneous solver for the heat transfer, thermoelectric, and electric transportation phenomena. Comparison with experimental results shows that the new solver could work well in the numerical calculations. The calculations predict that the Seebeck effect becomes larger for longer thermoelectric elements because of the larger temperature difference. The heat transfer to the cold surface is critical to determine the junction temperatures under a constant heat flux from the hot surface. The negative contribution from Peltier cooling and heating can be minimized when the current is smaller for longer elements. Therefore, a thicker TE module can generate more electric power even under a constant heat flux.

Suzuki, Ryosuke O.; Fujisaka, Takeyuki; Ito, Keita O.; Meng, Xiangning; Sui, Hong-Tao

2014-08-01

347

Polar heating in Saturn's thermosphere  

NASA Astrophysics Data System (ADS)

A 3-D numerical global circulation model of the Kronian thermosphere has been used to investigate the influence of polar heating. The distributions of temperature and winds resulting from a general heat source in the polar regions are described. We show that both the total energy input and its vertical distribution are important to the resulting thermal structure. We find that the form of the topside heating profile is particularly important in determining exospheric temperatures. We compare our results to exospheric temperatures from Voyager occultation measurements (Smith et al., 1983; Festou and Atreya, 1982) and auroral H3+ temperatures from ground-based spectroscopic observations (e.g. Miller et al., 2000). We find that a polar heat source is consistent with both the Smith et al. determination of T?~400 K at ~30° N and auroral temperatures. The required heat source is also consistent with recent estimates of the Joule heating rate at Saturn (Cowley et al., 2004). However, our results show that a polar heat source can probably not explain the Festou and Atreya determination of T?~800 K at ~4° N and the auroral temperatures simultaneously. Keywords. Ionosphere (Planetary ionosphere) Magnetospherica physics (Planetary magnetospheres) Meterology and atmospheric dynamics (Thermospheric dynamics)

Smith, C. G. A.; Aylward, A. D.; Miller, S.; Müller-Wodarg, I. C. F.

2005-10-01

348

Transient heating in the upper atmosphere  

NASA Technical Reports Server (NTRS)

The time-dependent response of the upper atmosphere to transient heat sources is considered. The basic problem is that of heating a compressible, heat-conducting fluid, which is described in the one-dimensional case by an analytic solution. Comparisons with satellite drag data of such first-order solutions are shown to be useful in determining energy requirements and in determining some constraints on the spatial distribution of the heating. Recent OGO-6 mass spectrometer and interferometric temperature measurements show that atmospheric disturbances during geomagnetic storms are much more prominent in the auroral zones. These results suggest that joule dissipation of auroral currents are important contributors to orbital perturbations of satellites.

Thomas, G. E.

1972-01-01

349

Radiatively heated high voltage pyroelectric crystal pulser  

NASA Astrophysics Data System (ADS)

Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

Antolak, A. J.; Chen, A. X.; Leung, K.-N.; Morse, D. H.; Raber, T. N.

2014-01-01

350

Technology, applications and modelling of ohmic heating: a review.  

PubMed

Ohmic heating or Joule heating has immense potential for achieving rapid and uniform heating in foods, providing microbiologically safe and high quality foods. This review discusses the technology behind ohmic heating, the current applications and thermal modeling of the process. The success of ohmic heating depends on the rate of heat generation in the system, the electrical conductivity of the food, electrical field strength, residence time and the method by which the food flows through the system. Ohmic heating is appropriate for processing of particulate and protein rich foods. A vast amount of work is still necessary to understand food properties in order to refine system design and maximize performance of this technology in the field of packaged foods and space food product development. Various economic studies will also play an important role in understanding the overall cost and viability of commercial application of this technology in food processing. Some of the demerits of the technology are also discussed. PMID:25328171

Varghese, K Shiby; Pandey, M C; Radhakrishna, K; Bawa, A S

2014-10-01

351

Analysis of the starting time of the Joule-Thomson microliquefier  

NASA Astrophysics Data System (ADS)

A statistical analysis is presented of the starting time of throttle-type microliquefiers with Hampson and Parkinson heat-exchangers working in open cycles. The correlation equations derived indicate that the dependence of the starting time on the gas pressure has the form of In t = a + b 1n p and is independent of the type of heat-exchanger or the kind of the working gas.

Bodio, E.; Wilczek, M.

352

Empirically corrected HEAT method for calculating atomization energies  

SciTech Connect

We describe how to increase the accuracy ofthe most recent variants ofthe HEAT method for calculating atomization energies of molecules by means ofextremely simple empirical corrections that depend on stoichiometry and the number ofunpaired electrons in the molecule. Our corrections reduce the deviation from experiment for all the HEAT variants. In particular, our corrections reduce the average absolute deviation and the root-mean-square deviation ofthe 456-QP variant to 0.18 and 0.23 kJoule/mol (i.e., 0.04 and 0.05 kcallmol), respectively.

Brand, Holmann V [Los Alamos National Laboratory

2008-01-01

353

Compact design improves efficiency and CAPEX -- combining plate heat exchangers and gas-liquid separators for gas processing savings  

SciTech Connect

This paper presents the unique combination of two well proven technologies: a compact large scale welded plate heat exchanger with a gas-liquid separator within the same pressure vessel. Explained are the benefits for raw gas processing on production sites where cost, weight and efficiency are of particular importance. Application of this Combined Heat Exchanger-Separator is presented for various gas processing schemes: Turbo Expander, Mechanical Refrigeration and Joule-Thompson.

Waintraub, L.; Sourp, T. [Proser (France)

1998-12-31

354

Scaling, stability, and fusion mechanisms. Studies using plasma focus devices from tens of kilojoules to tenth of joules  

SciTech Connect

Fusion studies using plasma focus devices from tens of kilojoules to less than one joule performed at the Chilean Nuclear Energy Commission are presented. The similarity of the physical behavior and the scaling observed in these machines are emphasized. Experiments on actual devices show that scaling holds at least through six order of magnitude. In particular all of these devices, from the largest to the smallest, keep the same quantity of energy per particle. Therefore, fusion reactions are possible to be obtained in ultraminiature devices (driven by generators of 0.1 J), as they are in the bigger devices (driven by generators of 1 MJ). However, the stability of the plasma depends on the size and energy of the device.

Soto, Leopoldo; Pavez, Cristian; Moreno, Jose; Cardenas, Miguel [Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Tarifeno, Ariel [Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Universidad de Concepcion (Chile)

2009-01-21

355

Role of Thermal Heating on the Voltage Induced Insulator-Metal Transition in VO2  

NASA Astrophysics Data System (ADS)

We show that the main mechanism for the dc voltage or dc current induced insulator-metal transition in vanadium dioxide VO2 is due to local Joule heating and not a purely electronic effect. This “tour de force” experiment was accomplished by using the fluorescence spectra of rare-earth doped micron sized particles as local temperature sensors. As the insulator-metal transition is induced by a dc voltage or dc current, the local temperature reaches the transition temperature indicating that Joule heating plays a predominant role. This has critical implications for the understanding of the dc voltage or dc current induced insulator-metal transition and has a direct impact on applications which use dc voltage or dc current to externally drive the transition.

Zimmers, A.; Aigouy, L.; Mortier, M.; Sharoni, A.; Wang, Siming; West, K. G.; Ramirez, J. G.; Schuller, Ivan K.

2013-02-01

356

Role of thermal heating on the voltage induced insulator-metal transition in VO2.  

PubMed

We show that the main mechanism for the dc voltage or dc current induced insulator-metal transition in vanadium dioxide VO(2) is due to local Joule heating and not a purely electronic effect. This "tour de force" experiment was accomplished by using the fluorescence spectra of rare-earth doped micron sized particles as local temperature sensors. As the insulator-metal transition is induced by a dc voltage or dc current, the local temperature reaches the transition temperature indicating that Joule heating plays a predominant role. This has critical implications for the understanding of the dc voltage or dc current induced insulator-metal transition and has a direct impact on applications which use dc voltage or dc current to externally drive the transition. PMID:23414038

Zimmers, A; Aigouy, L; Mortier, M; Sharoni, A; Wang, Siming; West, K G; Ramirez, J G; Schuller, Ivan K

2013-02-01

357

Heat pipe array heat exchanger  

DOEpatents

A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

Reimann, Robert C. (Lafayette, NY)

1987-08-25

358

A theoretical estimation of the pre-breakdown-heating time in the underwater discharge acoustic source  

NASA Astrophysics Data System (ADS)

One of the common characteristics of the electrothermal breakdown in an underwater discharge acoustic source (UDAS) is the existence of a pre-breakdown-heating phase. In our experiment, two phenomena were observed: (1) the breakdown time that takes on high randomicity and obeys a “double-peak" stochastic distribution; (2) the higher salt concentration that reduces the residual voltage and causes 100% non-breakdown. The mechanism of electrothermal breakdown is analysed. To specify the end of the pre-breakdown-heating phase, a “border boiling" assumption is proposed, in which the breakdown time is assumed to be the time needed to heat the border water around the initial arc to 773 K. Based on this ‘border boiling’ assumption, the numerical simulation is performed to evaluate the effects of two heating mechanisms: the Joule heating from the ionic current, and the radiation heating from the initial arc. The simulation results verify the theoretical explanations to these two experiment phenomena: (1) the stochastic distribution of the radius of the initial arc results in the randomicity of the breakdown time; (2) the difference in efficiency between the radiation heating and the Joule heating determines that, in the case of higher salt concentration, more energy will be consumed in the pre-breakdown-heating phase.

Wang, Yi-Bo; Wang, Shang-Wu; Zeng, Xin-Wu

2012-05-01

359

Thin film heat flux sensors for accurate transient and unidirectional heat transfer analysis  

NASA Astrophysics Data System (ADS)

Heat flux measurement is needed in many heat transfer studies. For the best unbiased heat flux sensors (HFS), the heat flux is obtained using temperature measurements at different locations and also an inverse heat conduction method (function specification...) in order to calculate the heat flux. Systematic errors can come from the uncertainty in the wire thermocouples locations and from errors in the knowledge of distances between two consecutive wire thermocouples. The main idea in this work is to use thin film thermoresistances deposited on a flexible thin polymer substrate instead of wire thermocouples welded on metallic sample. The interest of using thin film thermoresistances instead of wire thermocouples is a lower disturbance due to the smaller thickness of the thin film sensors (typically less than 1?m) and a much better knowledge of the distances between the different thin film thermoresistances which are precisely defined in the mask used for the metallic thin film pattern fabrication. In this paper, we present the fabrication of the new heat flux sensor with thin film thermoresistances, the study of the effect of the self heating (due to Joule effect in thermoresistances) and the performances of this new HFS with the comparison with classical HFS using wire thermocouples. For this study, a symmetric experimental setup is used with metallic samples equipped with an etched foil heater and both classical and new HFS. For several heating conditions, it appears that a better accuracy is always obtained with the new HFS using thin film thermoresistances.

Azerou, B.; Garnier, B.; Lahmar, J.

2012-11-01

360

Modeling and optimization of thin disk structure for high power sub-joule laser  

NASA Astrophysics Data System (ADS)

We analyzed the transient response characteristics of Yb:YAG thin disk in to clarify the experimentally obtained advantages of pulsed pumping in 1-kHz repetition rate reported in ref. 2. We applied commercial 2D FEA software which can calculate transient response of thermal effects. The temperature distributions of thin disk in both the CW power of 125-W and the average power of pulsed 125-W have been calculated. Even the net heat power were same in both CW and pulsed pumping, the temperature distribution was lower in pulsed pumping which can provide higher O-O efficiency and smaller beam distortion. The time evolution of OPD in the pulsed pumping has been analyzed, too.

Severová, Patricie; Smrz, Martin; Chyla, Michal; Miura, Taisuke; Endo, Akira; Mocek, Tomáš

2013-05-01

361

The finite-amplitude behavior of the Joule mode under astrophysical conditions  

NASA Technical Reports Server (NTRS)

Magnetized astrophysical plasmas reveal a great deal of structure when spatially resolved. One possible explanation for this structuring is based on the existence of filamenting instabilities driven by radiation. In this paper, previous linear calculations are extended by considering the weakly nonlinear (finite-amplitude) development of such filamenting instabilities in magnetized unstratified plasmas. It is shown that under most conditions these instabilities (in particular, the Jouse model) are unstable at finite amplitude; in particular, in the temperature and plasma-beta domains characteristic of, for example, much of the solar transition region, these modes - which can be linearly stable under these conditions - become unstable to finite-amplitude perturbations. The relevance of this to the problem of heating the solar low transition region by current dissipation is discussed.

Bodo, G.; Massaglia, S.; Rosner, R.; Ferrari, A.

1991-01-01

362

Numerical Studies of Fluid Leakage from a Geologic DisposalReservoir for CO2 Show Self-Limiting Feedback between Fluid Flow and HeatTransfer  

SciTech Connect

Leakage of CO2 from a hypothetical geologic storage reservoir along an idealized fault zone has been simulated, including transitions between supercritical, liquid, and gaseous CO2. We find strong non-isothermal effects due to boiling and Joule-Thomson cooling of expanding CO2. Leakage fluxes are limited by limitations in conductive heat transfer to the fault zone. The interplay between multiphase flow and heat transfer effects produces non-monotonic leakage behavior.

Pruess, Karsten

2005-03-22

363

Measurement and control of the movable coil position of a joule balance with a system based on a laser heterodyne interferometer  

NASA Astrophysics Data System (ADS)

A system based on laser heterodyne interferometer is proposed in this paper to measure and control the movable coil position of a joule balance. A damping system is used to suppress the movement of the movable coil in the horizontal direction while a piezoelectric ceramic control unit with PID controller is used to inhibit the vibration and long term drift of the movable coil in the vertical direction. The effectiveness of the proposed method in measuring and controlling the movable coil position of a joule balance is proved through experiments. Experimental results indicate that the displacement of the movable coil in the vertical direction can be reduced from 400 to 50 nm while its drift is successfully inhibited.

Yang, Hongxing; Lu, Yunfeng; Hu, Pengcheng; Li, Zhengkun; Zeng, Tao; He, Qing; Zhang, Zhonghua; Tan, Jiubin

2014-06-01

364

Applicability of the Joule-Thomson Cryocooler Coupled with Membrane-Based Purification System for Liquefaction of Natural Gas in Small Quantities  

Microsoft Academic Search

Joule-Thomson (J-T) cryocoolers using gas mixture have been studied theoretically and experimentally for a variety of applications. Gas separation technology using polymer membrane is emerging. In this paper the concept of coupling the J-T cooler with a hollow fiber membranes is presented. The apparatus can be used in many applications, like compressed natural gas (CNG) purification and condensation into LNG

A. Piotrowska; M. Chorowski

2008-01-01

365

2.4-Joule chirped pulse operation by a laser-diode-pumped slab laser for pumping non-collinear OPCPA  

NASA Astrophysics Data System (ADS)

We present a diode-pumped chirped pulse amplification (CPA) system that generates multi-joule energy at a central wavelength of 1054 nm at a repetition rate of 10 Hz. The purpose of this laser is to serve as a pump source for non-collinear optical parametric chirped pulse amplification (NOPCPA). A Nd-doped glass slab with zigzag optical path was used as the gain medium of the main amplifier in this system to obtain multi-joule output with repeatable operation. The Nd:glass zigzag slab amplifier system consists of four-pass pre-amplification and four-pass power amplification. The seed pulse that is fed to the main amplifier was generated by a mode-locked fiber oscillator emitting at a 1053 nm central wavelength. The oscillator output was pulse-stretched to 2.7 ns duration with a 4.5 nm spectral bandwidth and amplified to 100 ?J by optical parametric amplification by use of type-I BBO crystals. After the main amplification, 2.4 J of energy in 3.7 nm of spectral bandwidth at 1 Hz repetition rate was obtained. This spectral bandwidth corresponds to a transform-limited pulse duration of 440 fs. This result indicates that our CPA laser is capable of delivering multi-joule pump light after pulse compression and frequency doubling for 30-TW NOPCPA system.

Kurita, T.; Sueda, K.; Sekine, T.; Kawashima, T.; Miyanaga, N.

2010-08-01

366

Unsteady Couette Flow With Heat Transfer Considering Ion-Slip  

NASA Astrophysics Data System (ADS)

The unsteady Couette flow of an electrically conducting, viscous, incompressible fluid bounded by two parallel non-conducting porous plates is studied with heat transfer taking ion-slip into consideration. An external uniform magnetic field and a uniform suction and injection are applied perpendicular to the plates while the fluid motion is subjected to a constant pressure gradient. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are included in the energy equation. The effect of ion-slip an uniform suction and injection on both the velocity and temperature distributions is examined.

Attia, Hazem Ali

2005-11-01

367

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

E-print Network

Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger ...

Hansen, B J; Klebaner, A; 10.1063/1.4706971

2012-01-01

368

Heat dissipation property of cover glasses with heat sink films for transparent organic light-emitting diodes  

NASA Astrophysics Data System (ADS)

We investigate the thermal property of cover glasses with heat sink films and provide useful design guidelines of heat sinks for transparent organic light-emitting diodes (OLEDs). To this end, we inquire into the thermal effect of the thickness of cover glasses, Cu sheet or Cu strip lines attached to cover glasses, transparent metal meshes and polymer composite films fabricated on cover glasses, and their position (i.e., inner or outer surface of the cover glass). It is found that the heat sink property varies depending sensitively on the heat sink position and cover glass thickness. To enhance the heat transfer (sink) property, it is preferred to attach the heat sink to the inner surface of the cover glass without any air involved. If no heat sink is used, then thicker cover glasses are required to dissipate the Joule heat effectively. With high-transparency (>80%) metal meshes, we have achieved about 7% heat dissipation. The polymer composite films (poly(methyl methacrylate) (PMMA) binder mixed with cubic-boron nitride (c-BN) filler) show poor heat sink property due to difficulty in establishing an enough heat transfer pathway using a small amount of fillers.

Park, J. W.; Lee, J. H.

2014-09-01

369

Experimental study of a mixed refrigerant Joule-Thomson cryocooler using a commercial air-conditioning scroll compressor  

NASA Astrophysics Data System (ADS)

Mixed refrigerant Joule-Thomson (MR J-T) cryocoolers have been used to create cryogenic temperatures and are simple, efficient, cheap, and durable. However, compressors for MR J-T cryocoolers still require optimization. As the MR J-T cryocooler uses a commercial scroll compressor developed for air-conditioning systems, compressor overheating due to the use of less optimized refrigerants may not be negligible, and could cause compressor malfunction due to burn-out of scroll tip seals. Therefore, in the present study, the authors propose procedures to optimize compressor operation to avoid the overheating issue when the MR J-T cryocooler is used with a commercial oil lubricated scroll compressor, and the present experimental results obtained for a MR J-T cryocooler. A single stage 1.49 kW (2 HP) scroll compressor designed for R22 utilizing a mixture of nitrogen and hydrocarbons was used in the present study. As was expected, compressor overheating and irreversible high temperatures at a compressor discharge port were found at the beginning of compressor operation, which is critical, and hence, the authors used a water injection cooling system for the compressor to alleviate temperature overshooting. In addition, a portion of refrigerant in the high-pressure stream was by-passed into the compressor suction port. This allowed an adequate compression ratio, prevented excessive temperature increases at the compressor discharge, and eventually enabled the MR J-T cryocooler to operate stably at 121 K. The study shows that commercial oil lubricated scroll compressors can be used for MR J-T cryocooling systems if care is exercised to avoid compressor overheating.

Lee, Jisung; Lee, Kyungsoo; Jeong, Sangkwon

2013-05-01

370

Cryogenic Joule annealing induced large magnetic field response of Co-based microwires for giant magneto-impedance sensor applications  

NASA Astrophysics Data System (ADS)

We have presented herein the results of microstructure, surface magnetic domains (SMDs), and giant magneto-impedance (GMI) effect of melt-extracted Co68.15Fe4.35Si12.25B11.25Nb2Cu2 amorphous wires for the first time employed by using a cryogenic Joule annealing (CJA) technique with large DC current amplitude. Compared with the conventional JA method, experimental results indicate that the maximum GMI ratio [?Z/Z0]max achieves up to 425% at 8.1 MHz with monotonic increase of the axial magnetic field Hex up to 6.5 Oe for 300 mA (equal to around 1.06 × 106 A/dm-2) CJA-ed wire, which is about 75% larger than the [?Z/Z0]max for the 100 mA (nearly 3.53 × 105 A/dm-2) JA-ed microwires. The remarkable features of large and linearly sensitive response field (2.5 ˜ 6.5 Oe) and the sensitivity of 99.4%/Oe with higher GMI ratio simultaneously make the CJA tailored melt-extracted microwires promising candidate materials for miniaturized GMI sensors. Another interesting result of GMI profiles of 200 mA (appropriately equal to 7.07 × 105 A/dm-2) CJA-ed wire show a linear response to Hex (ranging from 10 to 80 Oe or more), this behavior of GMI curves can be explored to fabricate bi-sensor. Large response field proves to originate from the intensive coupling between the radial stress field and the circumferential magnetic field during CJA process. The effect of outer-shell microstructure and complex SMD for 300 mA CJA-ed microwire is attributed to the fact that liquid nitrogen hinders the evolution of circumferential domain structure to some extent and protects the amorphous structure in the shell region.

Chen, D. M.; Xing, D. W.; Qin, F. X.; Liu, J. S.; Shen, H. X.; Peng, H. X.; Wang, H.; Sun, J. F.

2014-08-01

371

Highly lead-loaded red plastic scintillators as an X-ray imaging system for the Laser Mega Joule  

SciTech Connect

The scope of this project intends to record spatially resolved images of core shape and size of a DT micro-balloon during Inertial Confinement Fusion (ICF) experiments at Laser Mega Joule facility (LMJ). We need to develop an X-ray imaging system which can operate in the radiative background generated by an ignition shot of ICF. The scintillator is a part of the imaging system and has to gather a compromise of scintillating properties (scintillating efficiency, decay time, emission wavelength) so as to both operate in the hard radiative environment and to allow the acquisition of spatially resolved images. Inorganic scintillators cannot be used because no compromise can be found regarding the expected scintillating properties, most of them are not fast enough and emit blue light. Organic scintillators are generally fast, but present low X-ray absorption in the 10 to 40 keV range, that does not permit the acquisition of spatially resolved images. To this aim, we have developed highly lead-loaded and red-fluorescent fast plastic scintillators. Such a combination is not currently available via scintillator suppliers, since they propose only blue-fluorescent plastic scintillators doped with up to 12%w Pb. Thus, incorporation ratio up to 27%w Pb has been reached in our laboratory, which can afford a plastic scintillator with an outstanding Z{sub eff} close to 50. X-rays in the 10 to 40 keV range can thus be detected with a higher probability of photoelectric effect than for classic organic scintillators, such as NE102. The strong orange-red fluorescence can be filtered, so that we can eliminate residual Cerenkov light, generated by {gamma}-ray absorption in glass parts of the imaging system. Decay times of our scintillators evaluated under UV excitation were estimated to be in the range 10 to 13 ns. (authors)

Hamel, M.; Normand, S. [CEA, LIST, Laboratoire Capteurs et Architectures Electroniques, F-91191 Gif-sur-Yvette (France); Turk, G.; Darbon, S. [CEA, DAM, DIF, F-91297 Arpajon (France)

2011-07-01

372

Impulsive chromospheric heating of two-ribbon flares by the fast reconnection mechanism  

SciTech Connect

Chromospheric heating of two-ribbon flares is quantitatively studied for different values of R{sub 0}, the ratio of the chromospheric plasma density to the coronal one, on the basis of the spontaneous fast reconnection model. In general, occurrence of impulsive chromospheric joule heating is delayed for the larger R{sub 0} because of more Alfven traveling time in the chromosphere. Once the chromospheric heating occurs, the temperature becomes more than 30 times its initial value for the case of R{sub 0}=400 in a pair of layers of deep chromosphere, and the region of high temperature shifts upward and becomes broader with time, since the chromospheric thin layer of joule heating shifts upward according to a pileup of reconnected field lines in the flare loop; then, chromospheric evaporation grows and extends outward, and its velocity becomes comparable with the coronal downflow velocity inside the loop boundary. The impulsive chromospheric heating is caused by drastic evolution of the flare current wedge, through which some part of the coronal sheet current suddenly turns its direction to be concentrated into the chromospheric thin layer; simultaneously, a magnetohydrodynamic (MHD) generator arises ahead of the flare loop top to provide a new current circuit inside the large-scale flare current wedge. Hence, it is concluded that the powerful MHD generator, sustained by the fast reconnection jet, drives the flare current wedge to evolve, leading to the impulsive chromospheric heating.

Ugai, M. [Research Center for Space and Cosmic Evolution, Ehime University, Matsuyama 790-8577 (Japan)

2008-03-15

373

Heating of Micro-protrusions in Accelerating Structures  

E-print Network

The thermal and field emission of electrons from protrusions on metal surfaces is a possible limiting factor on the performance and operation of high-gradient room temperature accelerator structures. We present here the results of extensive numerical simulations of electrical and thermal behavior of protrusions. We unify the thermal and field emission in the same numerical framework, describe bounds for the emission current and geometric enhancement, then we calculate the Nottingham and Joule heating terms and solve the heat equation to characterize the thermal evolution of emitters under RF electric field. Our findings suggest that, heating is entirely due to the Nottingham effect, that thermal runaway scenarios are not likely, and that high RF frequency causes smaller swings in temperature and cooler tips. We build a phenomenological model to account for the effect of space charge and show that space charge eliminates the possibility of tip melting, although near melting temperatures reached.

Keser, A C; Nusinovich, G S; Kashyn, D G; Jensen, K L

2013-01-01

374

Hydrogen evolution in nickel-water heat pipes.  

NASA Technical Reports Server (NTRS)

A study was made of the evolution of hydrogen gas in nickel-water heat pipes for the purpose of investigating methods of accelerated life testing. The data were analyzed in terms of a phenomenological corrosion model of heat pipe degradation which incorporates corrosion and oxidation theory and contains parameters which can be determined by experiment. The gas was evolved with a linear time dependence and an exponential temperature dependence with an activation energy of 1.03 x 10 to the minus 19th joules. A flow-rate dependence of the gas evolution was found in the form of a threshold. The results were used to predict usable lifetimes of heat pipes operated at normal operating conditions from results taken under accelerated operating conditions.

Anderson, W. T.

1973-01-01

375

Evaluation of the invasion heat for the HTS current lead using YBCO  

NASA Astrophysics Data System (ADS)

Current leads using high- TC superconductors (HTS current leads) are one of cryogenic key devices to assemble compact superconducting magnets such as applied for maglev trains etc. It is essential to evaluate effective thermal conductance through a HTS current lead package together with evaluating Joule heat and critical current for efficient design that has high current capacity and low heat invasion. We have designed the 500 A class HTS current lead package using a YBCO rod whose size is ? 3 × 30 mm, and developed an apparatus to measure its heat invasion. Temperature drop as a function of heat flow between the two ends of the package was measured by a conventional steady heat flow method. The quantity of heat invasion of the package under typical practical conditions, from 80 K hot end to 20 K cold end, was 163 mW. This value was simulated to the total value of 158 mW by counting contributions of all the component materials.

Endoh, R.; Kato, H.; Izumi, T.; Shiohara, Y.

376

Coronal Heating and the Solar Wind Acceleration  

NASA Astrophysics Data System (ADS)

The twisting magnetic field as the DC energy injection will produce charge separation and consequently an electric field parallel to the magnetic field. Accelerated beam electrons (a few times thermal velocity) due to this electric filed will be stopped by classical collisions with ambient electrons and ions. The beam electrons, 10-3 of the bulk electrons, do not create electric currents due to the back streaming bulk electrons. Hence it is not the normal or anomalous Joule heating, but a co-spatial frictional heating, and yet bulk heating. The heating rate is the kinetic energy density of beams multiplied by the classical collision frequency, and is about 10-4 erg cm-3 s-1. It successfully reproduces observations of quiet and active regions, including the RTV scaling law. In the open field, the damping length of this Alfvénic twist is 0.4 solar radii. This is appropriate to produce slow and high-speed solar winds. Ion-cyclotron waves may be excited due to supra-thermal beams.

Hirayama, T.

377

Heat Illness  

MedlinePLUS

... dangerous levels and you can develop a heat illness. Most heat illnesses occur from staying out in ... Heat-related illnesses include Heatstroke - a life-threatening illness in which body temperature may rise above 106° ...

378

Performance evaluation of heat exchanger for mixed refrigerant J-T cryocooler  

NASA Astrophysics Data System (ADS)

In mixed refrigerant Joule-Thomson cryocooler, a multi-component mixture of nitrogen-hydrocarbons undergoes evaporation and condensation process in a helical coiled heat exchanger simultaneously at different pressures. Experimental data and empirical correlations for predicting heat transfer coefficients of evaporating and condensing streams of multi-component mixtures at cryogenic temperatures are unavailable. As a result, design of these heat exchangers is a challenging task. The present work aims to address this challenge. It assesses the existing condensation correlations against the calculated data obtained during experimentation. Experiments are conducted to determine overall heat transfer coefficients along the length of the heat exchanger for various mixtures. The paper studies the applicability of these correlations to the multi-component mixtures at cryogenic temperatures.

Ardhapurkar, P. M.; Sridharan, Arunkumar; Atrey, M. D.

2014-09-01

379

Transient Heat Transfer Measurements in Forced Flow of He II at High Velocities  

NASA Astrophysics Data System (ADS)

Transient heat transfer is investigated in forced flow of He II for velocities up to 22 m/s. The flow is generated in a 10 mm ID, 0.85 m long straight test section instrumented with heaters, thermometers and pressure transducers. Rectangular heat pulses are generated in the flow and the temperature is measured at several locations as the pulses are carried by the forced flow with their shape being transformed by counterflow heat transfer. The linear pressure drop in the flow also results in a linear temperature gradient due to the Joule-Thomson effect and therefore has an influence in the heat transfer process. The effectiveness of the counterflow heat transfer also appears to decrease at the highest flow velocities.

Fuzier, S.; Van Stiver, S. W.

2006-04-01

380

Electrical heating of soils using high efficiency electrode patterns and power phases  

DOEpatents

Powerline-frequency electrical (joule) heating of soils using a high efficiency electrode configuration and power phase arrangement. The electrode configuration consists of several heating or current injection electrodes around the periphery of a volume of soil to be heated, all electrodes being connected to one phase of a multi-phase or a single-phase power system, and a return or extraction electrode or electrodes located inside the volume to be heated being connected to the remaining phases of the multi-phase power system or to the neutral side of the single-phase power source. This electrode configuration and power phase arrangement can be utilized anywhere where powerline frequency soil heating is applicable and thus has many potential uses including removal of volatile organic compounds such as gasoline and tricholorethylene (TCE) from contaminated areas.

Buettner, Harley M. (Livermore, CA)

1999-01-01

381

Analysis of Core Plasma Heating by Relativistic Electrons in Fast Ignition  

SciTech Connect

To investigate core plasma heating in fast ignition, a relativistic Fokker-Planck code for fast electrons is developed in a one-dimensional planar coordinates system. It is found that in dense plasmas, the Joule heating is much smaller than the heating through Coulomb interactions. In the latter energy deposition process, the long-range collective effect is comparable to that of binary electron-electron collisions. Moreover, on the basis of coupled transport-hydrodynamic simulations in one-dimensional planar geometry, the core heating process for an ignition-experiment-grade compressed core ({rho}R = 0.3 g/cm{sup 2}) is examined, and a possibility of evaluation of burn history from the neutron spectrum is shown. It is shown that a relatively low energy component (E{sub 0} {<=} 1 MeV) of electron beams plays an important role for effective core heating in fast ignition.

Johzaki, Tomoyuki [Osaka University (Japan); Mima, Kunioki [Osaka University (Japan); Nakao, Yasuyuki [Kyushu University (Japan); Yokota, Tomohiro [Kyushu University (Japan); Sumita, Hiroyuki [Kyushu University (Japan)

2003-05-15

382

Contact glow discharge electrolysis: a study on its origin in the light of the theory of hydrodynamic instabilities in local solvent vaporisation by Joule heating during electrolysis  

Microsoft Academic Search

Normal electrolysis at high voltages switches over spontaneously to contact glow discharge electrolysis. The transition is profoundly facilitated by raising the temperature and\\/or lowering the surface tension of the electrolyte. Results of a systematic study on the influence of these two factors on the breakdown voltage for normal electrolysis have been critically analysed. It has been concluded that solvent vaporisation

Susanta K. Sengupta; Ashok K. Srivastava; Rajeshwar Singh

1997-01-01

383

Optical cell with periodic resistive heating for the measurement of heat, mass, and thermal diffusions in liquid mixtures  

SciTech Connect

A new technique for the measurement of heat, mass, and thermal diffusions in liquids has been developed. Similar to laser induced dynamic gratings, a temperature grating is created in the sample. Thermal expansion transforms the temperature into a refractive-index grating, which is read by diffraction of a readout laser beam. In a multicomponent mixture an additional concentration grating is formed by thermal diffusion driven by the temperature gradients of the temperature grating. Differently to laser induced dynamic grating experiments we use Joule heating instead of optical heating. For that purpose we have built cuvettes which have a grating of transparent conducting strips on the inner side of one of their windows. If heated by an electric current a temperature grating will build up in the sample. Both the heat equation and the extended diffusion equation have been solved in two dimensions to allow for quantitative data analysis. Our apparatus and method of analysis have been validated by measurements of heat, mass, and thermal diffusions in pure and binary liquids. Heat diffusion can be correctly determined as was shown for pure toluene, pure dodecane, and the symmetric mixture of isobutylbenzene dodecane. Mass and thermal diffusions were studied in the three symmetric mixtures of dodecane, isobutylbenzene, and tetralin. The obtained diffusion and Soret coefficients agree with the literature values within the experimental errors. Uncompensated transient heating effects limit the resolution of the experimental technique.

Hartung, M.; Koehler, W. [Physikalisches Institut, Universitaet Bayreuth, D-95440 Bayreuth (Germany)

2007-08-15

384

Heating Safety  

MedlinePLUS

... for heating. • Have a qualified professional install stationary space heating equipment, water heaters or central heating equipment according to the local codes and manufacturer’s instructions. • Maintain heating ... • For fuel burning space heaters, always use the proper fuel as specified ...

385

Heat pumps  

NSDL National Science Digital Library

What electric heating system is the most efficient in moderate climates? This reading, part of a series about the future of energy, introduces students to the modern heat pump. Students read about the efficiency of heat pumps and the three types currently being used in homes. A simple explanation of how a heat pump works is offered. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

386

Empirical analysis of contributing factors to heating in lithium-ion cells: Anode entropy versus internal resistance  

NASA Astrophysics Data System (ADS)

Charging a battery beyond its maximum capacity can lead both to cell overheating and to the venting of gasses. A fundamental understanding of cell heating could lead to the development of real-time sensors that anticipate and avert catastrophic battery failure. Joule heating (also called ohmic or resistive heating) from cell internal resistance (Rint) dominates the overall thermal energy (?Q) generated during charging. Contrary to prior hypotheses, though, Joule heating does not appear to contribute to venting observed during overcharging. In this manuscript, we examine an alternate hypothesis, that heat released by the entropy change in the anode (?Sanode) and the concomitant increase in the anode temperature (Tanode) triggers the venting. Using our recently developed non-invasive battery internal temperature (BIT) sensor to monitor Tanode, we separated the contributions of ?Sanode, Rint and the anode resistance (Ranode) to ?Q. These quantities were tracked during constant current charging of a 18650 Lithium-ion cell, from zero state of charge (SoC) to overcharge. The resulting analysis suggests that anode entropy change is more important than resistive heating resulting from Ranode to the overall thermal energy. Anode entropy measurements, enabled by the BIT sensor, might serve as an alternative or adjunct method for anticipating and avoiding cell venting events.

Srinivasan, Rengaswamy; Carkhuff, Bliss G.

2013-11-01

387

Heating of microprotrusions in accelerating structures  

NASA Astrophysics Data System (ADS)

The thermal and field emission of electrons from protrusions on metal surfaces is a possible limiting factor on the performance and operation of high-gradient room temperature accelerator structures. We present here the results of extensive numerical simulations of electrical and thermal behavior of protrusions. We unify the thermal and field emission in the same numerical framework, describe bounds for the emission current and geometric enhancement, then we calculate the Nottingham and Joule heating terms and solve the heat equation to characterize the thermal evolution of emitters under rf electric field. Our findings suggest that heating is entirely due to the Nottingham effect. The time dependence of the rf field leads to a time dependent tip temperature with excursion that depends weakly on rf frequency. We build a phenomenological model to account for the effect of space charge and show that space charge eliminates the possibility of copper tip melting for tips with radii less than 10?m with vacuum fields on their surface less than 12GV/m, and for rf frequencies above 1 GHz.

Keser, A. C.; Antonsen, T. M.; Nusinovich, G. S.; Kashyn, D. G.; Jensen, K. L.

2013-09-01

388

Nanowire heating by optical electromagnetic irradiation.  

PubMed

The dissipative absorption of electromagnetic energy by 1D nanoscale structures at optical frequencies is applicable to several important phenomena, including biomedical photothermal theranostics, nanoscale photovoltaic materials, atmospheric aerosols, and integrated photonic devices. Closed-form analytical calculations are presented for the temperature rise within infinite circular cylinders with nanometer-scale diameters (nanowires) that are irradiated at right angles by a continuous-wave laser source polarized along the nanowire's axis. Solutions for the heat source are compared to both numerical finite-difference time domain (FDTD) simulations and well-known Mie scattering cross sections for infinite cylinders. The analysis predicts that the maximum temperature increase is affected not only by the cylinder's composition and porosity but also by morphology-dependent resonances (MDRs) that lead to significant spikes in the local temperature at particular diameters. Furthermore, silicon nanowires with high thermal conductivities are observed to exhibit extremely uniform internal temperatures during electromagnetic heating to 1 part in 10(6), including cases where there are substantial fluctuations of the internal electric-field source term that generates the Joule heating. For a highly absorbing material such as carbon, much higher temperatures are predicted, the internal temperature distribution is nonuniform, and MDRs are not encountered. PMID:23061375

Roder, Paden B; Pauzauskie, Peter J; Davis, E James

2012-11-20

389

About the relative importance of compressional heating and current dissipation for the formation of coronal X-ray bright points  

NASA Astrophysics Data System (ADS)

Context. The solar corona is heated to high temperatures of the order of 106 K. The coronal energy budget and specifically possible mechanisms of coronal heating (wave, DC-electric fields, etc.) are poorly understood. This is particularly true for the formation of X-ray bright points (BPs) is concerned. Aims: We aim to investigate the energy budget, particularly the relative role and contribution of adiabatic compression versus current dissipation to the formation of coronal BPs. Methods: Our three-dimensional resistive MHD simulation starts with the extrapolation of the observed magnetic field from SOHO/MDI magnetograms, which are associated with a BP observed on 19 December 2006 by Hinode. The initial radially non-uniform plasma density and temperature distribution agrees with an equilibrium model of the chromosphere and corona. The plasma motion is included in the model as a source of energy for coronal heating. Results: Our investigation of the energy conversion owing to Lorentz force, pressure gradient force, and Ohmic current dissipation for this bright point shows the minor effect of Joule heating compared with the work done by pressure gradient force in increasing the thermal energy by adiabatic compression. Especially at the time when the temperature enhancement above the bright point starts to form, compressional effects are quite dominant over the direct Joule heating. Conclusions: Choosing non-realistic high resistivity in compressible MHD models for a simulation of solar corona can lead to unphysical consequences for the energy balance analysis, especially when local thermal energy enhancements are being considered.

Javadi, S.; Büchner, J.; Otto, A.; Santos, J. C.

2011-05-01

390

Designer heating  

Microsoft Academic Search

This article discusses the use of hydronic radiant heat as wall units and as systems installed in floors. Described are radiators made in Europe that are said to be superior to convective hydronic heat (the heating principal traditional baseboard units use). The new panel radiators are stocked by only a few US distributors and may cost 20 to 90 percent

1989-01-01

391

Heat hugger  

Microsoft Academic Search

A fireplace insert is disclosed which will efficiently heat the interior of a structure, enable control of fuel burn rate and temperature of heated air directed into the interior structure, and facilitate circulation of the heated air through the interior rooms of the structure via pressure differential created by the forced-air flow through the insert. The unit includes an airtight

Ruegg

1981-01-01

392

Heat Pipes  

NASA Technical Reports Server (NTRS)

Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

1991-01-01

393

Preliminary analysis of heat pipe heat exchangers for heat recovery  

Microsoft Academic Search

A preliminary analysis of fin tube heat pipe heat exchangers for air-to-air heat recovery was conducted. The analysis uses conventional heat exchanger design techniques and a new heat pipe design technique which includes probabilistic design of artery wick heat pipes. The heat transfer capability of the heat pipes may be matched with that of the finned tubes in order to

J. O. Amode; K. T. Feldman

1975-01-01

394

Designer heating  

SciTech Connect

This article discusses the use of hydronic radiant heat as wall units and as systems installed in floors. Described are radiators made in Europe that are said to be superior to convective hydronic heat (the heating principal traditional baseboard units use). The new panel radiators are stocked by only a few US distributors and may cost 20 to 90 percent more than for American-style units of equal heating capacity. Because of their attractiveness and custom sizes the units may be mounted on open walls. Also described are advances in radiant floor heating. New systems have improved plastic tubing, more installation options, smarter controls and better edge insulation. The disadvantage in radiant floor heating is that floors may not be covered by heavy carpets or rugs.

Flower, R.G.

1989-03-01

395

Multiphysics Modeling for Dimensional Analysis of a Self-Heated Molten Regolith Electrolysis Reactor for Oxygen and Metals Production on the Moon and Mars  

NASA Technical Reports Server (NTRS)

The technology of direct electrolysis of molten lunar regolith to produce oxygen and molten metal alloys has progressed greatly in the last few years. The development of long-lasting inert anodes and cathode designs as well as techniques for the removal of molten products from the reactor has been demonstrated. The containment of chemically aggressive oxide and metal melts is very difficult at the operating temperatures ca. 1600 C. Containing the molten oxides in a regolith shell can solve this technical issue and can be achieved by designing a self-heating reactor in which the electrolytic currents generate enough Joule heat to create a molten bath.

Dominguez, Jesus; Sibille, Laurent

2010-01-01

396

Significance of adiabatic compression in local heating of the solar corona  

NASA Astrophysics Data System (ADS)

An Investigation of the relative role and contribution of adiabatic compression versus current dissipation to local heating of an X-ray bright point(BP) in the solar corona is carried out. Using a 3D numerical simulation model LINMOD3d, we studied the energy conversion processes due to Lorentz force, pressure gradient force and Ohmic dissipation that increase the thermal energy of an X-ray BP by adiabatic compression. We found the role of compressional effects is quite dominant over the direct Joule heating in changing the temperature. Flux tube volume integration along the magnetic field shows that apart from quantitative comparison, energy conversion rates, total energies and works done by Lorentz and pressure gradient force are sharing the same dynamics. The temperature enhancement follows the same pattern. This indicates that heating this bright point might not need additional sources rather than the adiabatic compression.

Javadi Dogaheh, Setareh; Buechner, Joerg; Otto, Antonius; Carlo Santos, Jean

397

A Si/Glass Bulk-Micromachined Cryogenic Heat Exchanger for High Heat Loads: Fabrication, Test, and Application Results  

PubMed Central

This paper reports on a micromachined Si/glass stack recuperative heat exchanger with in situ temperature sensors. Numerous high-conductivity silicon plates with integrated platinum resistance temperature detectors (Pt RTDs) are stacked, alternating with low-conductivity Pyrex spacers. The device has a 1 × 1-cm2 footprint and a length of up to 3.5 cm. It is intended for use in Joule–Thomson (J–T) coolers and can sustain pressure exceeding 1 MPa. Tests at cold-end inlet temperatures of 237 K–252 K show that the heat exchanger effectiveness is 0.9 with 0.039-g/s helium mass flow rate. The integrated Pt RTDs present a linear response of 0.26%–0.30%/K over an operational range of 205 K–296 K but remain usable at lower temperatures. In self-cooling tests with ethane as the working fluid, a J–T system with the heat exchanger drops 76.1 K below the inlet temperature, achieving 218.7 K for a pressure of 835.8 kPa. The system reaches 200 K in transient state; further cooling is limited by impurities that freeze within the flow stream. In J–T self-cooling tests with an external heat load, the system reaches 239 K while providing 1 W of cooling. In all cases, there is an additional parasitic heat load estimated at 300–500 mW. PMID:20490284

Zhu, Weibin; White, Michael J.; Nellis, Gregory F.; Klein, Sanford A.; Gianchandani, Yogesh B.

2010-01-01

398

A Si/Glass Bulk-Micromachined Cryogenic Heat Exchanger for High Heat Loads: Fabrication, Test, and Application Results.  

PubMed

This paper reports on a micromachined Si/glass stack recuperative heat exchanger with in situ temperature sensors. Numerous high-conductivity silicon plates with integrated platinum resistance temperature detectors (Pt RTDs) are stacked, alternating with low-conductivity Pyrex spacers. The device has a 1 x 1-cm(2) footprint and a length of up to 3.5 cm. It is intended for use in Joule-Thomson (J-T) coolers and can sustain pressure exceeding 1 MPa. Tests at cold-end inlet temperatures of 237 K-252 K show that the heat exchanger effectiveness is 0.9 with 0.039-g/s helium mass flow rate. The integrated Pt RTDs present a linear response of 0.26%-0.30%/K over an operational range of 205 K-296 K but remain usable at lower temperatures. In self-cooling tests with ethane as the working fluid, a J-T system with the heat exchanger drops 76.1 K below the inlet temperature, achieving 218.7 K for a pressure of 835.8 kPa. The system reaches 200 K in transient state; further cooling is limited by impurities that freeze within the flow stream. In J-T self-cooling tests with an external heat load, the system reaches 239 K while providing 1 W of cooling. In all cases, there is an additional parasitic heat load estimated at 300-500 mW. PMID:20490284

Zhu, Weibin; White, Michael J; Nellis, Gregory F; Klein, Sanford A; Gianchandani, Yogesh B

2010-02-01

399

Heat Transfer  

Microsoft Academic Search

\\u000a We are now stepping into the traditional physical chemistry area known as thermodynamics. Thermodynamics is concerned with a change of the total energy of a system. A system is a body which performs work (–w) or gives away heat (?q); the same body can also receive work (+w) or heat (+q). Notice the sign: when you carry out work or

Predrag-Peter Ilich

400

Heat Problems.  

ERIC Educational Resources Information Center

Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…

Connors, G. Patrick

401

Global numerical simulation of heat and mass transfer for SiC bulk crystal growth by PVT  

NASA Astrophysics Data System (ADS)

A modeling approach for the numerical simulation of heat and mass transfer during SiC sublimation growth in inductively heated physical vapor transport (PVT) reactors is introduced. The physical model is based on the two-dimensional solution of the coupled differential equations describing mass conservation, momentum conservation, conjugate heat transfer including surface to surface radiation, multicomponent chemical species mass transfer and advective flow. The model also includes the Joule volume heat sources induced by the electromagnetic field. The evolution of the temperature profiles inside the crucible and of the crystallization front is studied. The radial temperature gradient at the crystal/gas interface causes strong radial non-uniformity of the growth rate and, in turn, influences the shape of the growing crystal. Results of calculations are compared to experimental observations to analyse the validity of the modeling approach. Both the computed growth rates, their temporal evolution and the shape of the growing crystal agree with experimental data.

Selder, M.; Kadinski, L.; Makarov, Yu.; Durst, F.; Wellmann, P.; Straubinger, T.; Hofmann, D.; Karpov, S.; Ramm, M.

2000-04-01

402

Studies of heat source driven natural convection. Ph.D. Thesis. Technical Report, Jul. 1974 - Aug. 1975  

NASA Technical Reports Server (NTRS)

Natural convection energy transport in a horizontal layer of internally heated fluid was measured for Rayleigh numbers from 1890 to 2.17 x 10 to the 12th power. The fluid layer is bounded below by a rigid zero-heat-flux surface and above by a rigid constant-temperature surface. Joule heating by an alternating current passing horizontally through the layer provides the uniform volumetric energy source. The overall steady-state heat transfer coefficient at the upper surface was determined by measuring the temperature difference across the layer and power input to the fluid. The correlation between the Nusselt and Rayleigh numbers for the data of the present study and the data of the Kulacki study is given.

Kulacki, F. A.; Emara, A. A.

1975-01-01

403

The effect of variable properties on the unsteady Couette flow with heat transfer considering the Hall effect  

NASA Astrophysics Data System (ADS)

The influence of temperature dependent viscosity and thermal conductivity on the transient Couette flow with heat transfer is studied. An external uniform magnetic field is applied perpendicular to the parallel plates and the Hall effect is taken into consideration. The fluid is acted upon by a constant pressure gradient. The two plates are kept at two constant but different temperatures and the viscous and Joule dissipations are considered in the energy equation. A numerical solution for the governing non-linear equations of motion and the energy equation is obtained. The effect of the Hall term and the temperature dependent viscosity and thermal conductivity on both the velocity and temperature distributions is examined.

Attia, Hazem Ali

2008-10-01

404

Heat pipe array heat exchanger  

Microsoft Academic Search

A heat exchanger is described for transferring heat between a first fluid and a second fluid in an absorption refrigeration system comprising: a first shell having an inlet for receiving the first fluid at a first elevated temperature and an outlet for discharging the first fluid at a first reduced temperature with the shell defining a free flow path for

Reimann

1987-01-01

405

Measurements of ions emission using ToF method and CR39 SSNTD in a Small Plasma Focus device of Hundreds of Joules  

NASA Astrophysics Data System (ADS)

Ion beam emission in plasma focus (PF) discharges was originally investigated to explain the strong forward anisotropy observed in the neutron emission when D2 is used as filling gas in the PF devices. Several properties of emitted deuteron beam, including its angular distribution and energy spectra in PF devices operating at energies from 1kJ to 1MJ, have been measured. At present there is a growing interest in the development of very small PF devices operating under 1kJ. As part of the very low energy (< 1kJ) PF devices physics characterization program carried out at the Chilean Nuclear Energy Commission, the charged particle emission is being studied when hydrogen (H2) and mixture (H2+ %Ar) is used as filling gas in the PF device. The experiments have been performed in a plasma focus device of 400 joules (PF-400J). In order to estimate the ion beam energy spectrum and its ionization degree, by means of the time of flight method, a graphite collector system operating in the bias ion collector mode was constructed. On the other hand, measurements of the energy and flux of the ions have been corroborated using CR39 SSNTD. Preliminary results mainly show the presence of hydrogen ions with an average energy of 40keV. Also, in some cases, copper (from anode) and aluminum (from insulator) ions with energies lower than 1keV have been observed.

Moreno, José; Pedreros, José; Soto, Leopoldo

2014-05-01

406

Magnetic and magnetoimpedance studies on controlled Joule annealed amorphous Co73Fe4.5Ni0.5Mn0.5Nb0.5Si4.2B16.8 alloy  

NASA Astrophysics Data System (ADS)

We report magnetic and magnetoimpedance (MI) properties of as-quenched and Joule annealed (with and without external magnetic field) amorphous Co73Fe4.5Ni0.5Mn0.5Nb0.5Si4.2B16.8 alloy composition. The Joule annealing in the presence of magnetic field induces not only surface microstructural changes but also favourable anisotropy. Dc magnetic measurements show controlled annealing enhances soft magnetic nature of the sample. Virgin ribbons show MS ˜ 125 emu/g with ?r ˜ 104 and exhibit large MI ratio of ˜100% at 3 MHz frequency. This MI ratio was further enhanced to 152% on Joule annealing (current density 0.85 × 107 A/m2) in the presence of applied magnetic field of 500 Oe. The field dependence MI shows a double-peak feature in as-spun ribbons, which is significantly enhanced for field annealed (FA) samples. The enhancement in MI and magnetic field sensitivity (?) in FA amorphous ribbons is attributed to the development of nanograins on the surface layer that strengthens the transverse magnetic structure.

Kumar Manna, Subhendu; Srinivas, V.

2014-05-01

407

Heat pipe heat exchanger for heat recovery in air conditioning  

Microsoft Academic Search

The heat pipe heat exchangers are used in heat recovery applications to cool the incoming fresh air in air conditioning applications. Two streams of fresh and return air have been connected with heat pipe heat exchanger to investigate the thermal performance and effectiveness of heat recovery system. Ratios of mass flow rate between return and fresh air of 1, 1.5

Mostafa A. Abd El-Baky; Mousa M. Mohamed

2007-01-01

408

Corrosive resistant heat exchanger  

DOEpatents

A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

Richlen, Scott L. (Annandale, VA)

1989-01-01

409

Modular Heat Exchanger With Integral Heat Pipe  

NASA Technical Reports Server (NTRS)

Modular heat exchanger with integral heat pipe transports heat from source to Stirling engine. Alternative to heat exchangers depending on integrities of thousands of brazed joints, contains only 40 brazed tubes.

Schreiber, Jeffrey G.

1992-01-01

410

Heat Pipes  

NASA Technical Reports Server (NTRS)

Bobs Candies, Inc. produces some 24 million pounds of candy a year, much of it 'Christmas candy.' To meet Christmas demand, it must produce year-round. Thousands of cases of candy must be stored a good part of the year in two huge warehouses. The candy is very sensitive to temperature. The warehouses must be maintained at temperatures of 78-80 degrees Fahrenheit with relative humidities of 38- 42 percent. Such precise climate control of enormous buildings can be very expensive. In 1985, energy costs for the single warehouse ran to more than $57,000 for the year. NASA and the Florida Solar Energy Center (FSEC) were adapting heat pipe technology to control humidity in building environments. The heat pipes handle the jobs of precooling and reheating without using energy. The company contacted a FSEC systems engineer and from that contact eventually emerged a cooperative test project to install a heat pipe system at Bobs' warehouses, operate it for a period of time to determine accurately the cost benefits, and gather data applicable to development of future heat pipe systems. Installation was completed in mid-1987 and data collection is still in progress. In 1989, total energy cost for two warehouses, with the heat pipes complementing the air conditioning system was $28,706, and that figures out to a cost reduction.

1990-01-01

411

Heating mechanisms in short-pulse laser-driven cone targets.  

PubMed

The fast ignitor is a modern approach to laser fusion that uses a short-pulse laser to initiate thermonuclear burn. In its simplest form the laser launches relativistic electrons that carry its energy to a precompressed fusion target. Cones have been used to give the light access to the dense target core through the low-density ablative cloud surrounding it. Here the ANTHEM implicit hybrid simulation model shows that the peak ion temperatures measured in recent cone target experiments arose chiefly from return current joule heating, mildly supplemented by relativistic electron drag. Magnetic fields augment this heating only slightly, but capture hot electrons near the cone surface and force the hot electron stream into filaments. PMID:16486715

Mason, R J

2006-01-27

412

Localized Heating on Silicon Field Effect Transistors: Device Fabrication and Temperature Measurements in Fluid  

PubMed Central

We demonstrate electrically addressable localized heating in fluid at the dielectric surface of silicon-on-insulator field-effect transistors via radio-frequency Joule heating of mobile ions in the Debye layer. Measurement of fluid temperatures in close vicinity to surfaces poses a challenge due to the localized nature of the temperature profile. To address this, we developed a localized thermometry technique based on the fluorescence decay rate of covalently attached fluorophores to extract the temperature within 2 nm of any oxide surface. We demonstrate precise spatial control of voltage dependent temperature profiles on the transistor surfaces. Our results introduce a new dimension to present sensing systems by enabling dual purpose silicon transistor-heaters that serve both as field effect sensors as well as temperature controllers that could perform localized bio-chemical reactions in Lab on Chip applications. PMID:19967115

Elibol, Oguz H.; Reddy, Bobby; Nair, Pradeep R.; Dorvel, Brian; Butler, Felice; Ahsan, Zahab; Bergstrom, Donald E.; Alam, Muhammad A.; Bashir, Rashid

2010-01-01

413

Thermodynamical calculation of metal heating in nanosecond exploding wire and foil experiments  

SciTech Connect

A method of thermodynamical calculation of thin metal wire heating during its electrical explosion is discussed. The technique is based on a calculation of Joule energy deposition taking into account the current wave form and the temperature dependence of the resistivity and heat capacity of the metal. Comparing the calculation to a set of exploding tungsten wire experiments demonstrates good agreement up to the time of melting. Good agreement is also demonstrated with resistive magnetohydrodynamics simulation. A similar thermodynamical calculation for Mo, Ti, Ni, Fe, Al, and Cu shows good agreement with experimental data. The thermodynamical technique is useful for verification of the voltage measurements in exploding wire experiments. This technique also shows good agreement with an exploding W foil experiment.

Sarkisov, G. S.; Rosenthal, S. E.; Struve, K. W. [Ktech Corporation, 10800 Gibson Boulevard, Albuquerque, New Mexico 87123 (United States); Sandia National Laboratories, Albuquerque, New Mexico 87110 (United States)

2007-04-15

414

Evidence for ultra-fast heating in intense-laser irradiated reduced-mass targets  

SciTech Connect

We report on an experiment irradiating individual argon droplets of 20 {mu}m diameter with laser pulses of several Joule energy at intensities of 10{sup 19} W/cm{sup 2}. K-shell emission spectroscopy was employed to determine the hot electron energy fraction and the time-integrated charge-state distribution. Spectral fitting indicates that bulk temperatures up to 160 eV are reached. Modelling of the hot-electron relaxation and generation of K-shell emission with collisional hot-electron stopping only is incompatible with the experimental results, and the data suggest an additional ultra-fast (sub-ps) heating contribution. For example, including resistive heating in the modelling yields a much better agreement with the observed final bulk temperature and qualitatively reproduces the observed charge state distribution.

Neumayer, P.; Gumberidze, A.; Hochhaus, D. C. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Frankfurt Institute for Advanced Studies FIAS, 60438 Frankfurt am Main (Germany); Aurand, B.; Stoehlker, T. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Costa Fraga, R. A.; Kalinin, A. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Ecker, B. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Grisenti, R. E. [Institut fuer Kernphysik, J. W. Goethe University Frankfurt, 60438 Frankfurt am Main (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Kaluza, M. C. [Helmholtz Institute Jena, 07743 Jena (Germany); IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Kuehl, T. [Johannes Gutenberg University Mainz, 55099 Mainz (Germany); Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany); Helmholtz Institute Jena, 07743 Jena (Germany); Polz, J. [IOQ Institute of Optics and Quantum Electronics, University of Jena (Germany); Reuschl, R. [ExtreMe Matter Institute EMMI and Research Division, GSI Helmholtzzentrum fuer Schwerionenforschung, 64291 Darmstadt (Germany); Winters, D.; Winters, N.; Yin, Z. [Helmholtzzentrum fuer Schwerionenforschung GSI, 64291 Darmstadt (Germany)

2012-12-15

415

Heating Mechanisms in Short-Pulse Laser-Driven Cone Targets  

SciTech Connect

The fast ignitor is a modern approach to laser fusion that uses a short-pulse laser to initiate thermonuclear burn. In its simplest form the laser launches relativistic electrons that carry its energy to a precompressed fusion target. Cones have been used to give the light access to the dense target core through the low-density ablative cloud surrounding it. Here the ANTHEM implicit hybrid simulation model shows that the peak ion temperatures measured in recent cone target experiments arose chiefly from return current joule heating, mildly supplemented by relativistic electron drag. Magnetic fields augment this heating only slightly, but capture hot electrons near the cone surface and force the hot electron stream into filaments.

Mason, R.J. [Applied Physics Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2006-01-27

416

Temperature Control at DBS Electrodes using Heat Sink: Experimentally Validated FEM Model of DBS lead Architecture  

PubMed Central

There is a growing interest in the use of Deep Brain Stimulation for the treatment of medically refractory movement disorders and other neurological and psychiatric conditions. The extent of temperature increases around DBS electrodes during normal operation (joule heating and increased metabolic activity) or coupling with an external source (e.g. MRI) remains poorly understood and methods to mitigate temperature increases are being actively investigated. We developed a heat transfer finite element method simulation of DBS incorporating the realistic architecture of Medtronic 3389 leads. The temperature changes were analyzed considering different electrode configurations, stimulation protocols, and tissue properties. The heat-transfer model results were then validated using micro-thermocouple measurements during DBS lead stimulation in a saline bath. FEM results indicate that lead design (materials and geometry) may have a central role in controlling temperature rise by conducting heat. We show how modifying lead design can effectively control temperature increases. The robustness of this heat-sink approach over complimentary heat-mitigation technologies follows from several features: 1) it is insensitive to the mechanisms of heating (e.g. nature of magnetic coupling); 2) does not interfere with device efficacy; and 3) can be practically implemented in a broad range of implanted devices without modifying the normal device operations or the implant procedure. PMID:22764359

Elwassif, Maged M.; Datta, Abhishek; Rahman, Asif; Bikson, Marom

2012-01-01

417

Probing and controlling photothermal heat generation in plasmonic nanostructures.  

PubMed

In the emerging field of thermoplasmonics, Joule heating associated with optically resonant plasmonic structures is exploited to generate nanoscale thermal hotspots. In the present study, new methods for designing and thermally probing thermoplasmonic structures are reported. A general design rationale, based on Babinet's principle, is developed for understanding how the complementary version of ideal electromagnetic antennae can yield efficient nanoscale heat sources with maximized current density. Using this methodology, we show that the diabolo antenna is more suitable for heat generation compared with its more well-known complementary structure, the bow-tie antenna. We also demonstrate that highly localized and enhanced thermal hot spots can be realized by incorporating the diabolo antenna into a plasmonic lens. Using a newly developed thermal microscopy method based on the temperature-dependent photoluminescence lifetime of thin-film thermographic phosphors, we experimentally characterize the thermal response of various antenna and superstructure designs. Data from FDTD simulations and the experimental temperature measurements confirm the validity of the design rationale. The thermal microscopy technique, with its robust sensing method, could overcome some of the drawbacks of current micro/nanoscale temperature measurement schemes. PMID:23437919

Coppens, Zachary J; Li, Wei; Walker, D Greg; Valentine, Jason G

2013-03-13

418

A General Coupled Mathematical Model of Electromagnetic Phenomena, Two-Phase Flow, and Heat Transfer in Electroslag Remelting Process Including Conducting in the Mold  

NASA Astrophysics Data System (ADS)

A transient three-dimensional finite-volume mathematical model has been developed to investigate the coupled physical fields in the electroslag remelting (ESR) process. Through equations solved by the electrical potential method, the electric current, electromagnetic force (EMF), and Joule heating fields are demonstrated. The mold is assumed to be conductive rather than insulated. The volume of fluid approach is implemented for the two-phase flow. Moreover, the EMF and Joule heating, which are the source terms of the momentum and energy sources, are recalculated at each iteration as a function of the phase distribution. The solidification is modeled by an enthalpy-porosity formulation, in which the mushy zone is treated as a porous medium with porosity equal to the liquid fraction. An innovative marking method of the metal pool profile is proposed in the experiment. The effect of the applied current on the ESR process is understood by the model. Good agreement is obtained between the experiment and calculation. The electric current flows to the mold lateral wall especially in the slag layer. A large amount of Joule heating around the metal droplet varies as it falls. The hottest region appears under the outer radius of the electrode tip, close to the slag/metal interface instead of the electrode tip. The metal pool becomes deeper with more power. The maximal temperature increases from 1951 K to 2015 K (1678 °C to 1742 °C), and the maximum metal pool depth increases from 34.0 to 59.5 mm with the applied current ranging from 1000 to 2000 A.

Wang, Qiang; He, Zhu; Li, Baokuan; Tsukihashi, Fumitaka

2014-08-01

419

Bayonet heat exchangers in heat-assisted Stirling heat pump  

SciTech Connect

The Multi-Temperature Heat Supply System is a research project creating a city energy system with lower environmental load. This system consists of a gas-fueled internal combustion engine and a heat-assisted Stirling heat pump utilizing shaft power and thermal power in a combination of several cylinders. The heat pump is mainly driven by engine shaft power and is partially assisted by thermal power from engine exhaust heat source. Since this heat pump is operated by proportioning the two energy sources to match the characteristics of the driving engine, the system is expected to produce cooling and heating water at high COP. This paper describes heat exchanger development in the project to develop a heat-assisted Stirling heat pump. The heat pump employs the Bayonet type heat exchangers (BHX Type I) for supplying cold and hot water and (BHX Type II) for absorbing exhaust heat from the driving engine. The heat exchanger design concepts are presented and their heat transfer and flow loss characteristics in oscillating gas flow are investigated. The main concern in the BHX Type I is an improvement of gas side heat transfer and the spirally finned tubes were applied to gas side of the heat exchanger. For the BHX Type II, internal heat transfer characteristics are the main concern. Shell-and-tube type heat exchangers are widely used in Stirling machines. However, since brazing is applied to the many tubes for their manufacturing processes, it is very difficult to change flow passages to optimize heat transfer and loss characteristics once they have been made. The challenge was to enhance heat transfer on the gas side to make a highly efficient heat exchanger with fewer parts. It is shown that the Bayonet type heat exchanger can have good performance comparable to conventional heat exchangers.

Yagyu, S.; Fukuyama, Y.; Morikawa, T.; Isshiki, N.; Satoh, I.; Corey, J.; Fellows, C.

1998-07-01

420

Ceramic heat pipe heat exchangers  

Microsoft Academic Search

High-temperature strength, resistance to corrosive atmospheres, and moderate cost combine to make ceramic materials an obvious choice for construction of high-temperature thermal energy recuperator systems. Despite these advantages, ceramic recuperators are steadily being replaced by metallic units at considerable sacrifice in maximum air or fuel preheat temperatures and hence in recovery efficiency. By constructing a recuperator from ceramic heat pipes,

W. A. Ranken

1976-01-01

421

Heat Transfer  

NSDL National Science Digital Library

In this inquiry activity students explore how heat transfers from one substance to another This inquiry activity was developed by a K-12 science teacher in the American Physiological SocietyÃÂs 2006 Frontiers in Physiology Program. The NSES Standards addressed by this activity are current as of the year of development. For more information on the Frontiers in Physiology Program, please visit www.frontiersinphys.org.

Ms. Leslie Van (Montgomery Blair High School)

2006-04-01

422

Heat exchange system for recycling stack heat  

Microsoft Academic Search

A heat exchange system is described for recycling waste heat leaving a building stack to supply heat to incoming fresh air or temper stored water of the building water storage system, wherein the building has a source of heat at constant temperature, such as a cooking facility, from which air conveying waste heat is drawn and impelled through a stack

Giuffre

1980-01-01

423

Waste heat recovery using heat pipe heat exchanger for heating automobile using exhaust gas  

Microsoft Academic Search

The feasibility of using heat pipe heat exchangers for heating applying automotive exhaust gas is studied and the calculation method is developed. Practical heat pipe heat exchanger is set up for heating HS663, a large bus. Simple experiments are carried out to examine the performance of the heat exchanger. It is shown that the experimental results, which indicate the benefit

Feng Yang; Xiugan Yuan; Guiping Lin

2003-01-01

424

Analysis on heat loss characteristics of a 10 kV HTS power substation  

NASA Astrophysics Data System (ADS)

A 10 kV High Temperature Superconducting power substation (10 kV HTS substation), supported by Chinese State 863 projects, was developed and has been running to supply power for several factories for more than two years at an industrial park of Baiyin, Gansu province in Northwest China. The system of the 10 kV HTS substation compositions, including a HTS cable, a HTS transformer, a SFCL, and a SMES, are introduced. The SMES works at liquid helium temperature and the other three apparatus operates under liquid nitrogen condition. There are mainly four types of heat losses existing in each HTS apparatus of the 10 kV HTS substation, including AC loss, Joule heat loss, conductive heat, and leak-in heat from cryostat. A small quantity of AC loss still exists due to the harmonic component of the current when it carries DC for HTS apparatus. The principle and basis for analysis of the heat losses are introduced and the total heat loss of each apparatus are calculated or estimated, which agree well with the test result. The analysis and result presented are of importance for the design of the refrigeration system.

Teng, Yuping; Dai, Shaotao; Song, Naihao; Zhang, Jingye; Gao, Zhiyuan; Zhu, Zhiqin; Zhou, Weiwei; Wei, Zhourong; Lin, Liangzhen; Xiao, Liye

2014-09-01

425

Quantifying heat transfer in DMD-based optoelectronic tweezers with infrared thermography  

NASA Astrophysics Data System (ADS)

Optoelectronic tweezers (OET) have emerged in recent years as a powerful form of optically-induced dielectrophoresis for addressing single cells and trapping individual nanostructures with DMD-based virtual-electrodes. In this technique an alternating electric field is used to induce a dipole within structures of interest while very low-intensity optical images are used to produce local electric field gradients that create dynamic trapping potentials. Addressing living cells, particularly for heat-sensitive cell lines, with OET's optical virtual-electrodes requires an in-depth understanding of heating profiles within OET devices. In this work we present quantitative measurements of the thermal characteristics of single-crystalline-silicon phototransistor based optoelectronic tweezers (PhOET). Midwave infrared (3 - 5 micron) thermographic imaging is used to determine relative heating in PhOET devices both with and without DMD-based optical actuation. Temperature increases of approximately 2°C from electrolyte Joule-heating are observable in the absence of DMD-illumination when glass is used as a support for PhOET devices. An additional temperature increase of no more than 0.2°C is observed when DMD-illumination is used. Furthermore, significantly reduced heating can be achieved when devices are fabricated in direct contact with a metallic heat-sink.

Pauzauskie, Peter J.; Hsu, Hsan-Yin; Jamshidi, Arash; Valley, Justin K.; Pei, Shao Ning; Wu, Ming C.

2010-02-01

426

Waste Heat Recovery from High Temperature Off-Gases from Electric Arc Furnace  

SciTech Connect

This article presents a study and review of available waste heat in high temperature Electric Arc Furnace (EAF) off gases and heat recovery techniques/methods from these gases. It gives details of the quality and quantity of the sensible and chemical waste heat in typical EAF off gases, energy savings potential by recovering part of this heat, a comprehensive review of currently used waste heat recovery methods and potential for use of advanced designs to achieve a much higher level of heat recovery including scrap preheating, steam production and electric power generation. Based on our preliminary analysis, currently, for all electric arc furnaces used in the US steel industry, the energy savings potential is equivalent to approximately 31 trillion Btu per year or 32.7 peta Joules per year (approximately $182 million US dollars/year). This article describes the EAF off-gas enthalpy model developed at Oak Ridge National Laboratory (ORNL) to calculate available and recoverable heat energy for a given stream of exhaust gases coming out of one or multiple EAF furnaces. This Excel based model calculates sensible and chemical enthalpy of the EAF off-gases during tap to tap time accounting for variation in quantity and quality of off gases. The model can be used to estimate energy saved through scrap preheating and other possible uses such as steam generation and electric power generation using off gas waste heat. This article includes a review of the historical development of existing waste heat recovery methods, their operations, and advantages/limitations of these methods. This paper also describes a program to develop and test advanced concepts for scrap preheating, steam production and electricity generation through use of waste heat recovery from the chemical and sensible heat contained in the EAF off gases with addition of minimum amount of dilution or cooling air upstream of pollution control equipment such as bag houses.

Nimbalkar, Sachin U [ORNL; Thekdi, Arvind [E3M Inc; Keiser, James R [ORNL; Storey, John Morse [ORNL

2014-01-01

427

Industrial Waste Heat for Greenhouse Heating.  

National Technical Information Service (NTIS)

The economical conditions of utilizing industrial waste heat for greenhouse heating has been investigated. The investment cost and yearly operational costs of greenhouses and heating systems have been calculated as a function of the temperature of waste h...

S. E. Ransmark

1983-01-01

428

Water and Space Heating Heat Pumps  

E-print Network

system is an integrated air conditioning, heating and domestic hot water heating system. This system provides demand hot water heating. It has the best savings and good payback with high recovery capacity. Also, the free cooling provided during water...

Kessler, A. F.

1985-01-01

429

Heat pump system  

DOEpatents

An air heating and cooling system for a building includes an expansion-type refrigeration circuit and a heat engine. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The heat engine includes a heat rejection circuit having a source of rejected heat and a primary heat exchanger connected to the source of rejected heat. The heat rejection circuit also includes an evaporator in heat exchange relation with the primary heat exchanger, a heat engine indoor heat exchanger, and a heat engine outdoor heat exchanger. The indoor heat exchangers are disposed in series air flow relationship, with the heat engine indoor heat exchanger being disposed downstream from the refrigeration circuit indoor heat exchanger. The outdoor heat exchangers are also disposed in series air flow relationship, with the heat engine outdoor heat exchanger disposed downstream from the refrigeration circuit outdoor heat exchanger. A common fluid is used in both of the indoor heat exchanges and in both of the outdoor heat exchangers. In a first embodiment, the heat engine is a Rankine cycle engine. In a second embodiment, the heat engine is a non-Rankine cycle engine.

Swenson, Paul F. (Cleveland, OH); Moore, Paul B. (Fedhaurn, FL)

1982-01-01

430

Summer HeatSummer Heat Heat stress solutions  

E-print Network

Gardening and Your Health: Gardening and Your Health: Summer HeatSummer Heat Heat stress solutions their effectiveness and possibly causing harmful reactions to the applicator. Allow yourself to acclimate to the heat, not cold. Flavored beverages, such as fruit juices, iced tea and lemonade, as long as their sugar and salt

Liskiewicz, Maciej

431

Heat pipes in modern heat exchangers  

Microsoft Academic Search

Heat pipes are very flexible systems with regard to effective thermal control. They can easily be implemented as heat exchangers inside sorption and vapour-compression heat pumps, refrigerators and other types of heat transfer devices. Their heat transfer coefficient in the evaporator and condenser zones is 103–105 W\\/m2K, heat pipe thermal resistance is 0.01–0.03 K\\/W, therefore leading to smaller area and

Leonard L. Vasiliev

2005-01-01

432

Heat-Exchanger/Heat-Pipe Interface  

NASA Technical Reports Server (NTRS)

Monolithic assembly reliable and light in weight. Heat exchanger and evaporator ends of heat pipes integrated in monolithic halves welded together. Interface assembly connects heat exchanger of furnace, reactor, or other power source with heat pipes carrying heat to radiator or power-consuming system. One of several concepts proposed for nuclear power supplies aboard spacecraft, interface useful on Earth in solar thermal power systems, heat engines, and lightweight cooling systems.

Snyder, H. J.; Van Hagan, T. H.

1987-01-01

433

Heat pipe heat exchanger design considerations  

Microsoft Academic Search

Typical heat pipe heat exchangers (HPHX) are described, along with their advantages, uses, and some problems in HPHX design, and a computer HPHX analysis program is discussed with required input data. The computer program is being developed for analysis of heat exchange performance by finned-tube HPHX and thread-puddle-artery heat pipes. Copper-water heat pipes and carbon steel-Dowtherm A heat pipes are

K. T. Feldman; D. C. Lu

1976-01-01

434

Citrate-capped gold nanoparticle electrophoretic heat production in response to a time-varying radiofrequency electric-field  

PubMed Central

The evaluation of heat production from gold nanoparticles (AuNPs) irradiated with radiofrequency (RF) energy has been problematic due to Joule heating of their background ionic buffer suspensions. Insights into the physical heating mechanism of nanomaterials under RF excitations must be obtained if they are to have applications in fields such as nanoparticle-targeted hyperthermia for cancer therapy. By developing a purification protocol which allows for highly-stable and concentrated solutions of citrate-capped AuNPs to be suspended in high-resistivity water, we show herein, for the first time, that heat production is only evident for AuNPs of diameters ? 10 nm, indicating a unique size-dependent heating behavior not previously observed. Heat production has also shown to be linearly dependent on both AuNP concentration and total surface area, and severely attenuated upon AuNP aggregation. These relationships have been further validated using permittivity analysis across a frequency range of 10 MHz to 3 GHz, as well as static conductivity measurements. Theoretical evaluations suggest that the heating mechanism can be modeled by the electrophoretic oscillation of charged AuNPs across finite length scales in response to a time-varying electric field. It is anticipated these results will assist future development of nanoparticle-assisted heat production by RF fields for applications such as targeted cancer hyperthermia. PMID:23795228

Corr, Stuart J.; Raoof, Mustafa; Mackeyev, Yuri; Phounsavath, Sophia; Cheney, Matthew A.; Cisneros, Brandon T.; Shur, Michael; Gozin, Michael; McNally, Patrick J.; Wilson, Lon J.; Curley, Steven A.

2013-01-01

435

Hydride heat pump with heat regenerator  

NASA Technical Reports Server (NTRS)

A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

Jones, Jack A. (Inventor)

1991-01-01

436

Heat pipe waste heat recovery boilers  

NASA Astrophysics Data System (ADS)

The use of heat pipes as transport devices in waste heat recovery boilers is examined. Test results show that heat pipes can efficiently extract heat from the hot gas stream and transfer it inside the pressure vessel for the steam generation process. The benefits of incorporating heat pipes into the design of waste heat recovery boilers include a highly compact package, a significant reduction in thermally induced stresses, double isolation of the steam from the heat source, an extended surface for improved efficiency in heat extraction, improved circulation and stability in the boiling regime, easy cleaning, individually replaceable tubes, and low flue gas pressure drop.

Littwin, D. A.; McCurley, J.

437

Dead heat  

SciTech Connect

This paper reports on the prospect of global warming. This paper proposes a workable solution, and a road map for getting there. The author explains how we became addicted to fossil fuels and evokes a bleak picture should this dependence continue. But the book also explores how industry can become a vehicle for solving, instead of precipitating, the global environmental crisis. The decoupling of energy from pollution can be accomplished without sacrificing prosperity by powering the economy with solar energy. Dead Heat takes us step by step to a greenhouse-friendly world fueled only by the sun.

Oppenheimer, M.; Boyle, R.H.

1990-01-01

438

Heat exchange system for recycling waste heat  

Microsoft Academic Search

Design of heat exchange system for recycling waste heat, such as that leaving a building stack or flue, to supply heat where needed, such as to incoming fresh air or to tempered stored water of the building water storage system, wherein the building has a source of heat at a constant temperature (such as a furnace, a cooking facility, or

A. A. Giuffre; A. F. Giuffre

1982-01-01

439

Heat transfer enhancement in heat exchangers  

Microsoft Academic Search

In the power generation industry, high performance heat exchangers are needed to promote substantial improvements in effective utilization of waste heat in low temperature heat recovery applications. High performance heat exchangers are also seriously needed in low temperature power and refrigeration cycles that operate on renewable base energy sources such as ocean thermal energy conversion, geothermal and solar energy systems.

Ohadi

1991-01-01

440

ABSORPTION HEAT PUMP IN THE DISTRICT HEATING  

E-print Network

.6 % by natural gas European Heat Pump Summit 2013, Nuremberg, 15-16.10.2013 #12;Heat production sources · DHP;Advantages: · recovering of low-grade heat · savings of natural gas annual consumption - 842,000 m3 Boiler, 116 MWth Boiler, 116 MWth Gas Turbine 31.52 MWel Heat Recovery Steam Generator, 63 t/h, 67 bar

Oak Ridge National Laboratory

441

Transient Heat Transport in Subcooled He II Associated with JT Effect  

SciTech Connect

Transient heat transport in subcooled He II has been investigated in a 1 m long rectangular channel with distributed contractions: one-closed end has a heater, while the other end is open to the He II bath. Experiments were conducted applying heat pulses and recording the temperature profile with seven Allan Bradley resistors placed along the channel. Cernox sensor was indium soldered on the heater surface to monitor the onset of film boiling. As the onset of heat pulse, the pressure at the heater surface increased because of phase change from subcooled He II to He I. Further increasing of heat pulse leads to coexistence of triple-phase, He I vapor layer, He I and subcooled He II, at the vicinity of heater surface. These effects induced instantaneous He II temperature drop along the channel, which is caused by Joule-Thomson (JT) effect. A simple model gives an approximate mechanism of pressure increase in the channel. The paper describes transient heat transport mechanism in the channel and discusses JT effect within the channel.

Maekawa, R.; Iwamoto, A.; Hamaguchi, S. [National Institute for Fusion Science, Toki, Gifu 509-5292 (Japan)

2004-06-23

442

Uniform and Non-uniform Thermoelement Subject to Lateral Heat Convection  

NASA Astrophysics Data System (ADS)

A general energy equation of quasi-one-dimensional heat flow in a longitudinal thermoelement (TE) of a curved side that is subjected to an electric field and convection heat transfer on the curved surface is developed. The energy equation is solved for the temperature distribution in two cases; uniform cross-section TE and non-uniform cross-section TE. Analytical solutions for a uniform cross-section TE with uniform electrical and thermophysical properties are obtained, whereas numerical solutions are provided for a non-uniform cross-section TE. Two parameters playing a vital role in the thermal performance of the TE are identified: the heat resistance ratio ( HRR) and the energy growing ratio ( EGR). The HRR represents the ratio of the longitudinal conduction maximum thermal resistance to the lateral convection maximum thermal resistance. The EGR represents the ratio of Joule's electrical heating to Fourier's heat conduction. The effects of varying these two parameters, as well as the TE geometry, have been thoroughly investigated.

Hameed, Amar Hasan; Kafafy, Raed

2013-03-01

443

Dual source heat pump  

DOEpatents

What is disclosed is a heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating the fluid in heat exchange relationship with a refrigerant fluid; at least two refrigerant heat exchangers, one for effecting heat exchange with the fluid and a second for effecting heat exchange between refrigerant and a heat exchange fluid and the ambient air; a compressor for efficiently compressing the refrigerant; at least one throttling valve for throttling liquid refrigerant; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circulating device and heat exchange fluid circuit for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and direction of flow of the refrigerant therethrough for selecting a particular mode of operation. The heat exchange fluid provides energy for defrosting the second heat exchanger when operating in the air source mode and also provides a alternate source of heat.

Ecker, Amir L. (Dallas, TX); Pietsch, Joseph A. (Dallas, TX)

1982-01-01

444

Segmented heat exchanger  

SciTech Connect

A segmented heat exchanger system for transferring heat energy from an exhaust fluid to a working fluid. The heat exchanger system may include a first heat exchanger for receiving incoming working fluid and the exhaust fluid. The working fluid and exhaust fluid may travel through at least a portion of the first heat exchanger in a parallel flow configuration. In addition, the heat exchanger system may include a second heat exchanger for receiving working fluid from the first heat exchanger and exhaust fluid from a third heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the second heat exchanger in a counter flow configuration. Furthermore, the heat exchanger system may include a third heat exchanger for receiving working fluid from the second heat exchanger and exhaust fluid from the first heat exchanger. The working fluid and exhaust fluid may travel through at least a portion of the third heat exchanger in a parallel flow configuration.

Baldwin, Darryl Dean (Lafayette, IN); Willi, Martin Leo (Dunlap, IL); Fiveland, Scott Byron (Metamara, IL); Timmons, Kristine Ann (Chillicothe, IL)

2010-12-14

445

Heat recovery method  

SciTech Connect

Heat is recovered by combining a heat transfer system including heat exchangers interconnected in a circulatory system, with a heat pump system. The heat pump system is preferably operated in accordance with the Lorenz-Principle. It is not necessary to divide the heat carrier circuit of the heat pump into two or three separate circulatory circuits. The heat carrier circuit of the heat pump can thus continue to operate unchanged even if the heat pump is switched off. For this purpose the warm heat carrier coming from a discharge fluid cooler, is heated further in a condenser of the heat pump and the cold heat carrier coming from a preheater or cooler group, is cooled further in an evaporator of the heat pump.

Richarts, F.

1985-04-16

446

Integrated Heat Pump (IHP) System Development - Air-Source IHP Control Strategy and Specifications and Ground-Source IHP Conceptual Design  

SciTech Connect

The integrated heat pump (IHP), as one appliance, can provide space cooling, heating, ventilation, and dehumidification while maintaining comfort and meeting domestic water heating needs in near-zero-energy home (NZEH) applications. In FY 2006 Oak Ridge National Laboratory (ORNL) completed development of a control strategy and system specification for an air-source IHP. The conceptual design of a ground-source IHP was also completed. Testing and analysis confirm the potential of both IHP concepts to meet NZEH energy services needs while consuming 50% less energy than a suite of equipment that meets current minimum efficiency requirements. This report is in fulfillment of an FY06 DOE Building Technologies (BT) Joule Milestone.

Murphy, Richard W [ORNL; Rice, C Keith [ORNL; Baxter, Van D [ORNL

2007-05-01

447

Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.  

PubMed

The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

2014-01-01

448

Nonlinear Radiation Heat Transfer Effects in the Natural Convective Boundary Layer Flow of Nanofluid Past a Vertical Plate: A Numerical Study  

PubMed Central

The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge–Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

2014-01-01

449

Unsteady Hartmann flow with heat transfer of a viscoelastic fluid considering the Hall effect  

NASA Astrophysics Data System (ADS)

The unsteady Hartmann flow, with heat transfer, of an electrically conducting incompressible non-Newtonian viscoelastic fluid between two parallel horizontal nonconducting porous plates is studied taking into consideration the Hall effect. A sudden uniform and constant-pressure gradient, an external uniform magnetic field that is perpendicular to the plates, and uniform suction and injection through the surface of the plates are applied. The two plates are kept at different but constant temperatures while the Joule and viscous dissipations are taken into consideration. Numerical solutions for the governing momentum and energy equations are obtained using finite-difference approximations. The effect of the Hall term, the parameter describing the non-Newtonian behavior, and the velocity of suction and injection on both the velocity and temperature distributions is examined.

Attia, H. A.

2004-02-01

450

Direct observation of resistive heating at graphene wrinkles and grain boundaries  

SciTech Connect

We directly measure the nanometer-scale temperature rise at wrinkles and grain boundaries (GBs) in functioning graphene devices by scanning Joule expansion microscopy with 50 nm spatial and 0.2K temperature resolution. We observe a small temperature increase at select wrinkles and a large (100 K) temperature increase at GBs between coalesced hexagonal grains. Comparisons of measurements with device simulations estimate the GB resistivity (8 150 X lm) among the lowest reported for graphene grown by chemical vapor deposition. An analytical model is developed, showing that GBs can experience highly localized resistive heating and temperature rise, most likely affecting the reliability of graphene devices. Our studies provide an unprecedented view of thermal effects surrounding nanoscale defects in nanomaterials such as graphene.

Grosse, Kyle L. [University of Illinois Urbana-Champaign; Dorgan, Vincent E. [University of Illinois at Urbana-Champaign, Urbana-Champaign; Estrada, David [University of Illinois at Urbana-Champaign, Urbana-Champaign; Wood, Joshua D. [University of Illinois at Urbana-Champaign, Urbana-Champaign; Vlassiouk, Ivan V [ORNL; Eres, Gyula [ORNL; Lyding, Joseph W [University of Illinois at Urbana-Champaign, Urbana-Champaign; King, William P. [University of Illinois at Urbana-Champaign, Urbana-Champaign; Pop, Eric [Stanford University

2014-01-01

451

Direct observation of resistive heating at graphene wrinkles and grain boundaries  

NASA Astrophysics Data System (ADS)

We directly measure the nanometer-scale temperature rise at wrinkles and grain boundaries (GBs) in functioning graphene devices by scanning Joule expansion microscopy with ˜50 nm spatial and ˜0.2 K temperature resolution. We observe a small temperature increase at select wrinkles and a large (˜100 K) temperature increase at GBs between coalesced hexagonal grains. Comparisons of measurements with device simulations estimate the GB resistivity (8-150 ? ?m) among the lowest reported for graphene grown by chemical vapor deposition. An analytical model is developed, showing that GBs can experience highly localized resistive heating and temperature rise, most likely affecting the reliability of graphene devices. Our studies provide an unprecedented view of thermal effects surrounding nanoscale defects in nanomaterials such as graphene.

Grosse, Kyle L.; Dorgan, Vincent E.; Estrada, David; Wood, Joshua D.; Vlassiouk, Ivan; Eres, Gyula; Lyding, Joseph W.; King, William P.; Pop, Eric

2014-10-01

452

Geothermal heat pumps for heating and cooling  

NASA Astrophysics Data System (ADS)

Naval Facilities Engineering Service Center (NFESC) has been tasked by Naval Shore Facilities Energy Office to evaluate the NAS Patuxent River ground-source heat pump (GHP) installation. A large part of a building's energy consumption consists of heating and air conditioning for occupant comfort. The space heating requirements are normally met by fossil-fuel-fired equipment or electric resistance heating. Cooling is provided by either air conditioners or heat pumps, both using electricity as an energy source.

Garg, Suresh C.

1994-03-01

453

Annales Geophysicae (2004) 22: 41334142 SRef-ID: 1432-0576/ag/2004-22-4133  

E-print Network

Union 2004 Annales Geophysicae Statistics of Joule heating in the auroral zone and polar cap using Abstract. We make a statistical study of ionospheric Joule heating with the Poynting flux method using six- hensive set of fitted Joule heating formulas expressing the Joule heating in given magnetic local time

Paris-Sud XI, Université de

454

Annales Geophysicae, 23, 20512068, 2005 SRef-ID: 1432-0576/ag/2005-23-2051  

E-print Network

Union 2005 Annales Geophysicae Assessment of ionospheric Joule heating by GUMICS-4 MHD simulation, AMIE ­ Published: 15 September 2005 Abstract. We investigate the Northern Hemisphere Joule heating from several Hemisphere Joule heating. Joule heating during a sub- storm is estimated from global observations, including

Ã?stgaard, Nikolai

455

Thin film ZT characterization using transient Harman technique Zhixi Bian, Yan Zhang, Holger Schmidt, Ali Shakouri  

E-print Network

and electrical impedance matching. The Joule heating contribution to the thermoelectric EMF is separated from the thin film only. Furthermore, not only Peltier effect, but also Joule heating (the red arrows indicate-symmetric and the Joule heating is distributed widely and non-uniformly. To check the contributions of Joule heating

456

Annales Geophysicae (2003) 21: 122 European Geosciences Union 2003 Geophysicae  

E-print Network

in a reduction of the estimated Joule heating integrated over the Northern Hemisphere by up to 20%. Locally, Joule heat- ing may decrease more than 50% in some regions. We also find that the calculated energy flux of Joule heating, this results in a decrease in the ratio between Joule heating and energy flux, sometimes

Ã?stgaard, Nikolai

457

Annales Geophysicae (2004) 22: 475496 European Geosciences Union 2004 Geophysicae  

E-print Network

10%, resulting in a reduction of the estimated Joule heating integrated over the Northern Hemisphere by up to 20%. Locally, Joule heat- ing may decrease more than 50% in some regions. We also find- bined with the reduction of Joule heating, this results in a decrease in the ratio between Joule heating

Paris-Sud XI, Université de

458

High heat flux single phase heat exchanger  

NASA Technical Reports Server (NTRS)

This paper presents the results obtained to date in a program to develop a high heat flux, single-phase heat exchanger for spacecraft thermal management. The intended application is a net generation interface heat exchanger to couple the crew module water thermal bus to the two-phase ammonia main thermal bus in the Space Station Freedom. The large size of the interface heat exchanger is dictated by the relatively poor water-side heat transfer characteristics. The objective of this program is to develop a single-phase heat transfer approach which can achieve heat fluxes and heat transfer coefficients comparable to those of the evaporation ammonia side. A new heat exchanger concept has been developed to meet these objecties. The main feature of this heat exchanger is that it can achieve very high heat fluxes with a pressure drop one to two orders of magnitude lower than those of previous microchannel or jet impingement high heat flux heat exchangers. This paper describes proof-of-concept experiments performed in air and water and presents analytical model of the heat exchanger.

Valenzuela, Javier A.; Izenson, Michael G.

1990-01-01

459

Heat Integrate Heat Engines in Process Plants  

E-print Network

Technology Conference, Houston, TX, June 17-19, 1986 CONSTANT TEMPERATLRE HEAT SINK TMI I a. IDEAL HEAT PUMP ac I CONSTANT TEMPERATURE HEAT SOURCE Tc I Figure 3. A Reversed Heat Engine THE PINCH In this section we analyze the problem of heat... integration of ideal engines with a process. The fundamental concepts so developed apply equally to real machines which are discussed in subsequent sec tions. In [1] we saw how fundamentally important the pinch concept is in the design of Heat Exchanger...

Hindmarsh, E.; Boland, D.; Townsend, D. W.

460

Multiple source heat pump  

DOEpatents

A heat pump apparatus for conditioning a fluid characterized by a fluid handler and path for circulating a fluid in heat exchange relationship with a refrigerant fluid, at least three refrigerant heat exchangers, one for effecting heat exchange with the fluid, a second for effecting heat exchange with a heat exchange fluid, and a third for effecting heat exchange with ambient air; a compressor for compressing the refrigerant; at least one throttling valve connected at the inlet side of a heat exchanger in which liquid refrigerant is vaporized; a refrigerant circuit; refrigerant; a source of heat exchange fluid; heat exchange fluid circuit and pump for circulating the heat exchange fluid in heat exchange relationship with the refrigerant; and valves or switches for selecting the heat exchangers and directional flow of refrigerant therethrough for selecting a particular mode of operation. Also disclosed are a variety of embodiments, modes of operation, and schematics therefor.

Ecker, Amir L. (Duncanville, TX)

1983-01-01

461

Active microchannel heat exchanger  

Microsoft Academic Search

The present invention is an active microchannel heat exchanger with an active heat source and with microchannel architecture. The active microchannel heat exchanger has (a) an exothermic reaction chamber; (b) an exhaust chamber; and (c) a heat exchanger chamber in thermal contact with the exhaust chamber, wherein (d) heat from the exothermic reaction chamber is convected by an exothermic reaction

Anna Lee Y. Tonkovich; Gary L. Roberts; Charles J. Call; Robert S. Wegeng; Yong Wang

2001-01-01

462

Heat pump defrosting operation  

Microsoft Academic Search

This patent describes improvements to the method of defrosting operation of a heat pump having a compressor, an interior heat exchanger, an exterior heat exchanger, an exterior fan for moving exterior air past the exterior heat exchanger, and a thermostatic control means for cycling the compressor on and off in accordance with heating demand. The improvement comprises: operating the exterior

M. Levine; J. Russo; V. Rigotti; N. Skogler

1990-01-01

463

Heat pump defrosting operation  

Microsoft Academic Search

This patent describes an improvement to the method of defrosting operation of a heat pump having a compressor, an interior heat exchanger, an exterior heat exchanger, an exterior fan for moving exterior air past the exterior heat enchanger, and a thermostatic control means for cycling the compressor on and off in accordance with heating demand. The improvement comprises: measuring at

M. Levine; J. Russo; V. Rigotti; N. Skogler

1990-01-01

464

Nitinol heat engines  

Microsoft Academic Search

Heat engines have recently been developed which utilize the remarkable properties of a nickel-titanium alloy called Nitinol to convert heat into mechanical energy. The design, principles of operation, and performance characteristics of a small prototype Nitinol heat engine are described. Emphasis is placed on the description of a simple heat engine invented by the author, in which a specially heat-treated

A. D. Johnson

1975-01-01

465

Waste heat recovery device  

Microsoft Academic Search

A cascade heat exchange system is described in which the heat given off in condensing a superheated vaporized refrigerant is used to vaporize carbon dioxide and to add sensible heat to a water system. The superheated discharge vapor of a refrigeration system is pumped into the shell side of a heat exchange vessel, where evaporative tube bundles absorb heat from

Barrow

1980-01-01

466

Heat recovery unit  

Microsoft Academic Search

A device is disclosed for recovery of heat from hot shell devices, particularly from motor-compressor units such as used in air conditioners, refrigeration systems and the like and which comprises a heat exchange coil in encircling, contacting heat exchange relationship to the hot shell device with circulation of a fluid through the heat exchange coil to recover normally wasted heat.

Beckett

1980-01-01

467

Heat storage units  

Microsoft Academic Search

A heat storage unit of the kind comprising a housing in which heat storage elements are contained, with a common passage extending through the heat storage elements, and through which air is fed by a fan to remove heat from the storage elements to apply the heat to the room being served by the unit is described. To permit the

1982-01-01

468

Heat pipe technology  

NASA Technical Reports Server (NTRS)

A bibliography of heat pipe technology to provide a summary of research projects conducted on heat pipes is presented. The subjects duscussed are: (1) heat pipe applications, (2) heat pipe theory, (3) design and fabrication, (4) testing and operation, (5) subject and author index, and (6) heat pipe related patents.

1972-01-01

469

Ceramic Heat Recuperators for Industrial Heat Recovery.  

National Technical Information Service (NTIS)

Results are presented from a continuing program whose purpose is to demonstrate the technical and economic feasibility of using ceramic heat recuperators for industrial heat recovery. The information presented can be used by engineers in industry to evalu...