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Sample records for magnetic specific heat

  1. Specific heat in diluted magnetic semiconductor quantum ring

    Science.gov (United States)

    Babanlı, A. M.; Ibragimov, B. G.

    2017-11-01

    In the present paper, we have calculated the specific heat and magnetization of a quantum ring of a diluted magnetic semiconductor (DMS) material in the presence of magnetic field. We take into account the effect of Rashba spin-orbital interaction, the exchange interaction and the Zeeman term on the specific heat. We have calculated the energy spectrum of the electrons in diluted magnetic semiconductor quantum ring. Moreover we have calculated the specific heat dependency on the magnetic field and Mn concentration at finite temperature of a diluted magnetic semiconductor quantum ring.

  2. Measurement of specific heat and specific absorption rate by nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Gultekin, David H., E-mail: david.gultekin@aya.yale.edu [Department of Electrical Engineering, Yale University, New Haven, CT 06520 (United States); Department of Medical Physics, Memorial Sloan-Kettering Cancer Center, New York, NY 10065 (United States); Department of Radiology, Memorial Sloan-Kettering Cancer Center, New York, NY 10065 (United States); Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232 (United States); Gore, John C. [Department of Biomedical Engineering, Vanderbilt University, Nashville, TN 37232 (United States); Department of Radiology and Radiological Sciences, Vanderbilt University, Nashville, TN 37232 (United States); Department of Molecular Physiology and Biophysics, Vanderbilt University, Nashville, TN 37232 (United States); Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37232 (United States); Institute of Imaging Science, Vanderbilt University, Nashville, TN 37232 (United States)

    2010-05-20

    We evaluate a nuclear magnetic resonance (NMR) method of calorimetry for the measurement of specific heat (c{sub p}) and specific absorption rate (SAR) in liquids. The feasibility of NMR calorimetry is demonstrated by experimental measurements of water, ethylene glycol and glycerol using any of three different NMR parameters (chemical shift, spin-spin relaxation rate and equilibrium nuclear magnetization). The method involves heating the sample using a continuous wave laser beam and measuring the temporal variation of the spatially averaged NMR parameter by non-invasive means. The temporal variation of the spatially averaged NMR parameter as a function of thermal power yields the ratio of the heat capacity to the respective nuclear thermal coefficient, from which the specific heat can be determined for the substance. The specific absorption rate is obtained by subjecting the liquid to heating by two types of radiation, radiofrequency (RF) and near-infrared (NIR), and by measuring the change in the nuclear spin phase shift by a gradient echo imaging sequence. These studies suggest NMR may be a useful tool for measurements of the thermal properties of liquids.

  3. Specific heat and magnetization of RMn2(H,D)2

    International Nuclear Information System (INIS)

    Tarnawski, Z.; Kolwicz-Chodak, L.; Figiel, H.; Kim-Ngan, N.-T.H.; Havela, L.; Miliyanchuk, K.; Sechovsky, V.; Santava, E.; Sebek, J.

    2007-01-01

    The effect of hydrogen absorption on magnetic and thermodynamic properties of hydrides compounds RMn 2 (H,D) 2 (R = Y, Nd, Tb, Ho, and Er) have been investigated by performing specific heat and magnetization measurements in the temperature range of 2-320 K and in magnetic fields up to 9 T. The phase transition to the antiferromagnetic order accompanying a crystal structure transformation have been revealed by complicated-structure anomalies in specific heat and weak anomalies in magnetization

  4. Magnetic susceptibility, specific heat and magnetic structure of CuNi2(PO4)2

    International Nuclear Information System (INIS)

    Escobal, Jaione; Pizarro, Jose L.; Mesa, Jose L.; Larranaga, Aitor; Fernandez, Jesus Rodriguez; Arriortua, Maria I.; Rojo, Teofilo

    2006-01-01

    The CuNi 2 (PO 4 ) 2 phosphate has been synthesized by the ceramic method at 800 deg. C in air. The crystal structure consists of a three-dimensional skeleton constructed from MO 4 (M II =Cu and Ni) planar squares and M 2 O 8 dimers with square pyramidal geometry, which are interconnected by (PO 4 ) 3- oxoanions with tetrahedral geometry. The magnetic behavior has been studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The bimetallic copper(II)-nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at, approximately, 29.8 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements exhibit a three-dimensional magnetic ordering (λ-type) peak at 29.5 K. The magnetic structure of this phosphate shows ferromagnetic interactions inside the Ni 2 O 8 dimers, whereas the sublattice of Cu(II) ions presents antiferromagnetic couplings along the y-axis. The change of the sign in the magnetic unit-cell, due to the [1/2, 0, 1/2] propagation vector determines a purely antiferromagnetic structure. - Graphical abstract: Magnetic structure of CuNi2(PO4)2

  5. Magnetic specific heat and magnetoresistance of URhSi

    Czech Academy of Sciences Publication Activity Database

    Prokeš, K.; Wand, T.; Andreev, Alexander V.; Meissner, M.; Honda, F.; Sechovský, V.

    2008-01-01

    Roč. 460, 1-2 (2008), s. 47-53 ISSN 0925-8388 Institutional research plan: CEZ:AV0Z10100520 Keywords : URhSi * calorimetry * ferromagnetism * magnetic measurements Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.510, year: 2008

  6. Specific heat and magnetism of a UIrGe single crystal

    Czech Academy of Sciences Publication Activity Database

    Sechovský, V.; Vejpravová, J.; Andreev, Alexander V.; Honda, F.; Prokeš, K.; Šantavá, Eva

    359-361, - (2005), s. 1126-1128 ISSN 0921-4526 Institutional research plan: CEZ:AV0Z10100520 Keywords : uranium intermetallics * antiferromagnetism * magnetic anisotropy * specific heat Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.796, year: 2005

  7. Magnetic ordering and specific heat analysis of TmPtSn

    Czech Academy of Sciences Publication Activity Database

    Vejpravová, J.; Svoboda, P.; Šebek, Josef; Janeček, M.; Komatsubara, T.

    2003-01-01

    Roč. 328, - (2003), s. 142-144 ISSN 0921-4526 R&D Projects: GA ČR GA106/02/0943 Grant - others:GA UK(CZ) 165/01; VACUUM PRAHA(CZ) 2002 Keywords : rare-earth intermetallic compounds * magnetic ordering * specific heat Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.908, year: 2003

  8. Specific heat and magnetism of LuFe.sub.6./sub.Al.sub.6./sub..

    Czech Academy of Sciences Publication Activity Database

    Svoboda, P.; Andreev, Alexander V.; Šantavá, Eva; Šebek, Josef

    2008-01-01

    Roč. 113, č. 1 (2008), s. 307-310 ISSN 0587-4246. [CSMAG'07. Košice, 09.07.2007-12.07.2007] Institutional research plan: CEZ:AV0Z10100520 Keywords : specific heat * LuFe 6 Al 6 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.321, year: 2008

  9. Specific heat and magnetic susceptibility vs long range order in V3Ga

    International Nuclear Information System (INIS)

    Junod, A.; Fluekiger, R.; Treyvaud, A.; Muller, J.

    1976-01-01

    A new technique of studying the magnetic susceptibility together with the specific heat and the superconducting transition of typical A15-type compounds in different ordering states enables us to consistently isolate the spin paramagnetism. Satisfactory results are obtained for V 3 Ga and these are compared with data on V 3 Au and Nb 3 (Au-Pt). (author)

  10. Specific heat of heavy-fermion CePd2Si2 in high magnetic fields

    International Nuclear Information System (INIS)

    Sheikin, I.; Wang, Y.; Bouquet, F.; Junod, A.; Lejay, P.

    2002-01-01

    We report specific heat measurements on the heavy-fermion compound CePd 2 Si 2 in magnetic fields up to 16 T and in the temperature range 1.4-16 K. A sharp peak in the specific heat signals the antiferromagnetic transition at T N ∼ 9.3 K in zero field. The transition is found to shift to lower temperatures when a magnetic field is applied along the crystallographic a-axis, while a field applied parallel to the tetragonal c-axis does not affect the transition. The magnetic contribution to the specific heat below T N is well described by a sum of a linear electronic term and an antiferromagnetic spin-wave contribution. Just below T N , an additional positive curvature, especially at high fields, arises most probably due to thermal fluctuations. The field dependence of the coefficient of the low-temperature linear term, γ 0 , extracted from the fits shows a maximum at about 6 T, at the point where an anomaly was detected in susceptibility measurements. The relative field dependences of both T N and the magnetic entropy at T N scale as [1-(B/B 0 ) 2 ] for B parallel a, suggesting the disappearance of antiferromagnetism at B 0 ∼42 T. The expected suppression of the antiferromagnetic transition temperature to zero makes the existence of a magnetic quantum critical point possible. (author). Letter-to-the-editor

  11. Symmetric Anderson impurity model: Magnetic susceptibility, specific heat and Wilson ratio

    Science.gov (United States)

    Zalom, Peter; Pokorný, Vladislav; Janiš, Václav

    2018-05-01

    We extend the spin-polarized effective-interaction approximation of the parquet renormalization scheme from Refs. [1,2] applied on the symmetric Anderson model by adding the low-temperature asymptotics of the total energy and the specific heat. We calculate numerically the Wilson ratio and determine analytically its asymptotic value in the strong-coupling limit. We demonstrate in this way that the exponentially small Kondo scale from the strong-coupling regime emerges in qualitatively the same way in the spectral function, magnetic susceptibility and the specific heat.

  12. Neutron diffraction, specific heat and magnetic susceptibility of Ni3(PO4)2

    International Nuclear Information System (INIS)

    Escobal, J.; Pizarro, J.L.; Mesa, J.L.; Rojo, J.M.; Bazan, B.; Arriortua, M.I.; Rojo, T.

    2005-01-01

    The Ni 3 (PO 4 ) 2 phosphate was synthesized by the ceramic method in air atmosphere. The crystal structure consists of a three-dimensional skeleton constructed from Ni 3 O 14 edge-sharing octahedra, which are interconnected by (PO 4 ) 3- oxoanions with tetrahedral geometry. The magnetic behavior was studied on powdered sample by using susceptibility, specific heat and neutron diffraction data. The nickel(II) orthophosphate exhibits a three-dimensional magnetic ordering at approximately 17.1 K. However, its complex crystal structure hampers any parametrization of the J-exchange parameter. The specific heat measurements of Ni 3 (PO 4 ) 2 exhibit a three-dimensional magnetic ordering (λ-type) peak at 17.1 K. Measurements above T N suggest the presence of a small short-range order in this phase. The total magnetic entropy was found to be 28.1 KJ/mol at 50 K. The magnetic structure of the nickel(II) phosphate exhibits ferromagnetic interactions inside the Ni 3 O 14 trimers which are antiferromagnetically coupled between them, giving rise to a purely antiferromagnetic structure

  13. Specific heat and magnetic properties of single-crystalline ZnxDyyCrzSe4 spinels

    International Nuclear Information System (INIS)

    Jendrzejewska, Izabela; Groń, Tadeusz; Maciążek, Ewa; Duda, Henryk; Kubisztal, Marian; Ślebarski, Andrzej; Pietrasik, Ewa; Fijałkowski, Marcin

    2016-01-01

    The crystal structure, magnetic isotherm, magnetic susceptibility, electrical conductivity and specific heat measurements for single-crystalline Zn x Dy y Cr z Se 4 (where x+y+z≈3) spinels are presented. A semiconducting behavior with the activation energy of 0.53 eV, an antiferromagnetic order with a Néel temperature T N =22 K and a strong ferromagnetic exchange evidenced by a positive Curie–Weiss temperature θ=79, 71 and 70 K with increasing Dy-content in the sequence 0.05, 0.13 and 0.19 were established. Below T N the magnetic field dependence of magnetization, M(H), shows two peaks at critical fields H c1 and H c2 . The values of H c1 decrease slightly with temperature, especially for the larger Dy-content, while the values of H c2 drop rapidly with temperature. The magnetic contribution to the specific heat displays a sharp peak at T N , which is strongly shifted to much lower temperatures in the applied magnetic fields. Similar behavior was found for the temperature dependence of the specific heat C(T) plotted as C(T)/T vs. T. The value of the magnetic and phonon contribution to the entropy at T N and at H=0 is only ∼4.8, ∼4.4 and ∼4.2 J mol −1 K −1 /Cr 3+ for y=0.05, 0.13 and 0.19, respectively, much lower than the average magnetic contribution S m =(z/2)Rln(2S+1)=12.33 J mol −1 K −1 /Cr 3+ calculated for Cr 3+ ion with S=3/2, as the dysprosium one is paramagnetic. - Highlights: • Dy-substitution does not affect the Cr 3+ 3d 3 electronic configuration and AFM order. • The larger Dy-content, the smaller FM short-range interactions. • The magnetic and phonon contribution to the entropy decreases as Dy-content increases.

  14. Specific heat and magnetization of a ZrB12 single crystal: characterization of a type II/1 superconductor

    OpenAIRE

    Wang, Yuxing; Lortz, Rolf; Paderno, Yuriy; Filippov, Vladimir; Abe, Satoko; Tutsch, Ulrich; Junod, Alain

    2005-01-01

    We measured the specific heat, the magnetization, and the magnetoresistance of a single crystal of ZrB12, which is superconducting below Tc ~ 6 K. The specific heat in zero field shows a BCS-type superconducting transition. The normal- to superconducting-state transition changes from first order (with a latent heat) to second order (without latent heat) with increasing magnetic field, indicating that the pure compound is a low-kappa, type-II/1 superconductor in the classification of Auer and ...

  15. New possibility of magnetic ripple shielding for specific heat measurements in hybrid magnets

    NARCIS (Netherlands)

    Tarnawski, Z.; Meulen, der, H. van; Franse, J.J.M.; Kadowaki, K.; Veenhuizen, P.A.; Klaasse, J.

    1988-01-01

    A test of the new high Tc superconducting materials for magnetic ripple shielding has been carried out. It was found that magnetic ripples of 0.0009 T (peak-to-peak) in the frequency range below 20 kHz can be completely shielded in high static fields by a 2 mm thick Y-Ba-Cu-O screen.

  16. Specific heat of S=1 quasi-1D antiferromagnet NDMAP in magnetic fields

    International Nuclear Information System (INIS)

    Tsujii, H.; Honda, Z.; Andraka, B.; Katsumata, K.; Takano, Y.

    2003-01-01

    NDMAP, Ni(C 5 H 14 N 2 ) 2 N 3 (PF 6 ), is a quasi-one-dimensional S=1 Heisenberg antiferromagnet with Haldane-gap energies of 22 and 5.5 K for excitations polarized parallel and perpendicular to the chain c-axis, respectively. We have extended the specific-heat measurements by Honda et al. in this compound to 150 mK in temperature and 18 T in magnetic field, employing a novel relaxation calorimeter. The experiment provides an accurate determination of the exponent for the transition line for the field-assisted ordered phase. In addition, a new feature has been found in the phase diagram at around 14 T

  17. Specific heat of the antiferro/ferro-magnet NpGa3

    International Nuclear Information System (INIS)

    Colineau, E.; Griveau, J.-C.; Wastin, F.; Rebizant, J.

    2011-01-01

    Research highlights: → The Actinide Research Department at ITU is devoted to basic and strategic research on actinide elements and compounds. The scientific programme encompasses both physics and chemistry, and is carried out in collaboration with a number of academic research partners worldwide. → The availability of state-of-the-art instrumentation adapted for measuring spectroscopic, thermodynamic and transport properties of radioactive samples, together with specialised facilities for preparation and characterisation of high quality samples, makes the department a centre of excellence in actinide research and one of the leading institutions in this field. → The object of actinide research is the understanding of chemical bonding in, and the solid-state physics properties of, the actinide metals and their compounds. The level of knowledge of actinides is far inferior to that of the rest of the periodic table, mainly because of the difficulty of handling transuranium materials, but also because of the inherent difficulty of understanding the behavior of the 5f-electrons. Their spatial extent and tendency to interact with electrons on ligand sites give actinide elements a complexity unique in the periodic table. Experiments and theory are performed with a view to improved understanding. - Abstract: The specific heat of NpGa 3 has been measured for the first time. The magnetic transitions and more generally the full magnetic phase diagram have been re-established precisely. The Sommerfeld coefficient and the magnetic entropy point to a rather localized system, in agreement with previous studies, in particular high pressure Moessbauer and resistivity. The comparison with other NpX 3 suggests that NpGa 3 is the most localized member of the series.

  18. Crystal-field study of magnetization and specific heat properties of frustrated pyrochlore Pr2Zr2O7

    International Nuclear Information System (INIS)

    Alam, J.; Jana, Y.M.; Biswas, A. Ali

    2016-01-01

    The experimental results of temperature dependent dc magnetic susceptibility, field dependent isothermal magnetization, magnetic specific heat and entropy of the pyrochlore Pr 2 Zr 2 O 7 are simulated and analyzed using appropriate D 3d crystal-field (CF) and anisotropic molecular field tensors at Pr-sites in the self-consistent mean-field approach involving four magnetically non-equivalent rare-earth spins on the tetrahedral unit of the pyrochlore structure. CF level pattern and wave-functions of the ground 3 H 4 multiplet of the Pr 3+ ions are obtained considering intermediate coupling between different Russell-Saunders terms of the 4f 2 electronic configurations of Pr-ion and J-mixing effects. CF analysis shows that the CF ground-state of the Pr 3+ ion in Pr 2 Zr 2 O 7 is a well-isolated doublet, with significant admixtures of terms coming from |M J =±4〉 and |M J =±1〉, and the Pr-spins are effectively Ising-like along the local <111> axes. Magnetic specific heat in zero-field is simulated by considering a temperature dependence of the exchange splitting of the ground doublet. - Highlights: • Full CF diagonalization using intermediate coupling and J-mixing. • Pr-spins are Ising-like along local [111] axis. • Magnetic specific heat is due to temperature dependence exchange splitting of ground CF doublet.

  19. Highly macroscopically degenerated single-point ground states as source of specific heat capacity anomalies in magnetic frustrated systems

    Science.gov (United States)

    Jurčišinová, E.; Jurčišin, M.

    2018-04-01

    Anomalies of the specific heat capacity are investigated in the framework of the exactly solvable antiferromagnetic spin- 1 / 2 Ising model in the external magnetic field on the geometrically frustrated tetrahedron recursive lattice. It is shown that the Schottky-type anomaly in the behavior of the specific heat capacity is related to the existence of unique highly macroscopically degenerated single-point ground states which are formed on the borders between neighboring plateau-like ground states. It is also shown that the very existence of these single-point ground states with large residual entropies predicts the appearance of another anomaly in the behavior of the specific heat capacity for low temperatures, namely, the field-induced double-peak structure, which exists, and should be observed experimentally, along with the Schottky-type anomaly in various frustrated magnetic system.

  20. Specific heat (1-330K), magnetic susceptiblity and Meissner effect Bi-(Pb)-Sr-Ca-Cu-O samples

    International Nuclear Information System (INIS)

    Junod, A.; Eckert, D.; Triscone, G.; Brunner, O.; Muller, J.; Zhao, Z.

    1989-01-01

    Five samples in the Bi 2 - y Pb y Sr 2 CaCu 2 O 8 + x system selected for their sharp diamagnetic transitions are characterized with particular emphasis on the specific heat. The behavior of the magnetic susceptibility upon doping with holes (Pb) is similar to that of the La 1 - y Sr y CuO 4 system

  1. Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

    Science.gov (United States)

    Lahiri, B. B.; Ranoo, Surojit; Philip, John

    2017-11-01

    Magnetic fluid hyperthermia (MFH) is becoming a viable cancer treatment methodology where the alternating magnetic field induced heating of magnetic fluid is utilized for ablating the cancerous cells or making them more susceptible to the conventional treatments. The heating efficiency in MFH is quantified in terms of specific absorption rate (SAR), which is defined as the heating power generated per unit mass. In majority of the experimental studies, SAR is evaluated from the temperature rise curves, obtained under non-adiabatic experimental conditions, which is prone to various thermodynamic uncertainties. A proper understanding of the experimental uncertainties and its remedies is a prerequisite for obtaining accurate and reproducible SAR. Here, we study the thermodynamic uncertainties associated with peripheral heating, delayed heating, heat loss from the sample and spatial variation in the temperature profile within the sample. Using first order approximations, an adiabatic reconstruction protocol for the measured temperature rise curves is developed for SAR estimation, which is found to be in good agreement with those obtained from the computationally intense slope corrected method. Our experimental findings clearly show that the peripheral and delayed heating are due to radiation heat transfer from the heating coils and slower response time of the sensor, respectively. Our results suggest that the peripheral heating is linearly proportional to the sample area to volume ratio and coil temperature. It is also observed that peripheral heating decreases in presence of a non-magnetic insulating shielding. The delayed heating is found to contribute up to ~25% uncertainties in SAR values. As the SAR values are very sensitive to the initial slope determination method, explicit mention of the range of linear regression analysis is appropriate to reproduce the results. The effect of sample volume to area ratio on linear heat loss rate is systematically studied and the

  2. Uncertainties in the estimation of specific absorption rate during radiofrequency alternating magnetic field induced non-adiabatic heating of ferrofluids

    International Nuclear Information System (INIS)

    Lahiri, B B; Ranoo, Surojit; Philip, John

    2017-01-01

    Magnetic fluid hyperthermia (MFH) is becoming a viable cancer treatment methodology where the alternating magnetic field induced heating of magnetic fluid is utilized for ablating the cancerous cells or making them more susceptible to the conventional treatments. The heating efficiency in MFH is quantified in terms of specific absorption rate (SAR), which is defined as the heating power generated per unit mass. In majority of the experimental studies, SAR is evaluated from the temperature rise curves, obtained under non-adiabatic experimental conditions, which is prone to various thermodynamic uncertainties. A proper understanding of the experimental uncertainties and its remedies is a prerequisite for obtaining accurate and reproducible SAR. Here, we study the thermodynamic uncertainties associated with peripheral heating, delayed heating, heat loss from the sample and spatial variation in the temperature profile within the sample. Using first order approximations, an adiabatic reconstruction protocol for the measured temperature rise curves is developed for SAR estimation, which is found to be in good agreement with those obtained from the computationally intense slope corrected method. Our experimental findings clearly show that the peripheral and delayed heating are due to radiation heat transfer from the heating coils and slower response time of the sensor, respectively. Our results suggest that the peripheral heating is linearly proportional to the sample area to volume ratio and coil temperature. It is also observed that peripheral heating decreases in presence of a non-magnetic insulating shielding. The delayed heating is found to contribute up to ∼25% uncertainties in SAR values. As the SAR values are very sensitive to the initial slope determination method, explicit mention of the range of linear regression analysis is appropriate to reproduce the results. The effect of sample volume to area ratio on linear heat loss rate is systematically studied and

  3. Enhanced specific absorption rate of bi-magnetic nanoparticles for heating applications

    Energy Technology Data Exchange (ETDEWEB)

    Hammad, Mohaned; Hempelmann, Rolf, E-mail: r.hempelmann@mx.uni-saarland.de

    2017-02-15

    Truncated octahedron bi-magnetic core/shell nanoparticles of Zn{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}@Zn{sub 0.4}Mn{sub 0.6}Fe{sub 2}O{sub 4} with different size distributions have been synthesized, and their structural and magnetic properties have been studied. The structure and morphology of the core/shell nanostructures were established by using X-ray diffraction, and transmission electron microscopy. Dark field-TEM and X-ray photoelectron spectroscopy results confirmed the formation of bi-magnetic core/shell nanoparticles. The synthesized nanoparticles are superparamagnetic at room temperature. The Curie temperature increases with the increase of particle size from 360 K to 394 K. The experimental results showed that core/shell nanoparticles have a higher specific absorption rate compared to the core ones. These nanoparticles are interfacial exchange coupled between hard and soft magnetic phases. We demonstrated that the specific absorption rate could be tuned by the concentration of precursor and the synthesis time. - Highlights: • Zn{sub 0.4}Co{sub 0.6}Fe{sub 2}O{sub 4}@Zn{sub 0.4}Mn{sub 0.6}Fe{sub 2}O{sub 4} nanoparticles were synthesized by seed-mediated growth method. • Exchange-coupling between magnetic hard and soft phase of the magnetic nanoparticles affects the specific absorption rate. • The specific absorption rate could be tuned by the concentration of precursor and the synthesis time. • An increase of the core/shell magnetic nanoparticles size resulted in the increase of Curie temperature.

  4. Monte Carlo study of internal energy and specific heat of a nano-graphene bilayer in a longitudinal magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Xiao-hong; Wang, Wei, E-mail: ww9803@126.com; Chen, Dong-dong; Xu, Si-yuan

    2016-06-15

    The thermodynamic properties of a nano-graphene bilayer, consisting of the upper layer A of spin-3/2 with antiferromagnetic intralayer exchange coupling and the bottom layer B of spin-5/2 with ferromagnetic intralayer exchange coupling, have been studied by the use of Monte Carlo simulation. We find a number of characteristic phenomena. The effects of the exchange coupling, the single-ion anisotropy and the longitudinal magnetic field on the internal energy, the specific heat and the blocking temperature of the mixed-spin bilayer system have been investigated in detail. The internal energy and the specific heat profiles are clarified. In particular, we have found that the specific heat curve may show two peaks phenomenon for appropriate values of the system parameters.

  5. Magnetic determination of the specific heat jump at Tc in YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Triscone, G.; Junod, A.; Muller, J.

    1989-01-01

    Magnetization measurements M(H,T) were performed on a polycrystalline YBa 2 Cu 3 O 7 - δ sample in the reversible region near T c . Thermodynamic relations are used to address the question: is the specific heat jump an intrinsic characteristic property of the electron system at the superconducting transition? It is shown that the measured data up to 8T (rather than extrapolated to H c2 ) already yield 45% of the calorimetric jump

  6. Specific heat of heavy-fermion CePd{sub 2}Si{sub 2} in high magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Sheikin, I. [University of Geneva, DPMC, Geneva (Switzerland)]. E-mail: Ilya.Sheikin@physics.unige.ch; Wang, Y.; Bouquet, F.; Junod, A. [University of Geneva, DPMC, Geneva (Switzerland); Lejay, P. [CRTBT, CNRS, Grenoble (France)

    2002-07-22

    We report specific heat measurements on the heavy-fermion compound CePd{sub 2}Si{sub 2} in magnetic fields up to 16 T and in the temperature range 1.4-16 K. A sharp peak in the specific heat signals the antiferromagnetic transition at T{sub N} {approx} 9.3 K in zero field. The transition is found to shift to lower temperatures when a magnetic field is applied along the crystallographic a-axis, while a field applied parallel to the tetragonal c-axis does not affect the transition. The magnetic contribution to the specific heat below T{sub N} is well described by a sum of a linear electronic term and an antiferromagnetic spin-wave contribution. Just below T{sub N}, an additional positive curvature, especially at high fields, arises most probably due to thermal fluctuations. The field dependence of the coefficient of the low-temperature linear term, {gamma}{sub 0}, extracted from the fits shows a maximum at about 6 T, at the point where an anomaly was detected in susceptibility measurements. The relative field dependences of both T{sub N} and the magnetic entropy at T{sub N} scale as [1-(B/B{sub 0}){sup 2}] for B parallel a, suggesting the disappearance of antiferromagnetism at B{sub 0}{approx}42 T. The expected suppression of the antiferromagnetic transition temperature to zero makes the existence of a magnetic quantum critical point possible. (author). Letter-to-the-editor.

  7. Rotary magnetic heat pump

    Science.gov (United States)

    Kirol, L.D.

    1987-02-11

    A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.

  8. Self-dual cluster renormalization group approach for the square lattice Ising model specific heat and magnetization

    International Nuclear Information System (INIS)

    Martin, H.O.; Tsallis, C.

    1981-01-01

    A simple renormalization group approach based on self-dual clusters is proposed for two-dimensional nearest-neighbour 1/2 - spin Ising model on the square lattice; it reproduces the exact critical point. The internal energy and the specific heat for vanishing external magnetic field, spontaneous magnetization and the thermal (Y sub(T)) and magnetic (Y sub(H)) critical exponents are calculated. The results obtained from the first four smallest cluster sizes strongly suggest the convergence towards the exact values when the cluster sizes increases. Even for the smallest cluster, where the calculation is very simple, the results are quite accurate, particularly in the neighbourhood of the critical point. (Author) [pt

  9. Magnetic field dependence of the specific heat of heavy-fermion YbCu4.5

    International Nuclear Information System (INIS)

    Amato, A.; Fisher, R.A.; Phillips, N.E.; Jaccard, D.; Walker, E.

    1990-03-01

    The specific heat of a polycrystalline sample of YbCu 4.5 has been measured between 0.3 and 20K in magnetic fields to 7T. At zero field a minimum in C/T is observed near 11K. Below that temperature C/T increases and below 0.5K exhibits an upturn ascribed to a hyperfine contribution. The increase in C/T below 11K is reduced by a factor 1.5 for H = 7T, whereas the hyperfine term is enhanced due to the contribution of the 63 Cu and 65 Cu and nuclei. 5 refs., 3 figs

  10. Model for the orientation, magnetic field, and temperature dependence of the specific heat of CeCu6

    International Nuclear Information System (INIS)

    Edelstein, A.S.

    1988-01-01

    The results of a model calculation of the orientation, magnetic field, and temperature dependence of the specific heat C of CeCu 6 are found to be in good agreement with the single-crystal data of Amato et al. The model incorporates both the Kondo and crystal-field effects. It is suggested that the low-temperature Wilson's ratio CTchi, where chi is the susceptibility, may not change in an applied field H and that both CT and chi at low temperatures as a function of H may be proportional to the many-body density of states at the energy μH

  11. Lattice specific heat for the RMIn5 (R=Gd, La, Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction

    International Nuclear Information System (INIS)

    Facio, Jorge I.; Betancourth, D.; Cejas Bolecek, N.R.; Jorge, G.A.; Pedrazzini, Pablo; Correa, V.F.; Cornaglia, Pablo S.; Vildosola, V.; García, D.J.

    2016-01-01

    We analyze theoretically a common experimental process used to obtain the magnetic contribution to the specific heat of a given magnetic material. In the procedure, the specific heat of a non-magnetic analog is measured and used to subtract the non-magnetic contributions, which are generally dominated by the lattice degrees of freedom in a wide range of temperatures. We calculate the lattice contribution to the specific heat for the magnetic compounds GdMIn 5 (M=Co, Rh) and for the non-magnetic YMIn 5 and LaMIn 5 (M=Co, Rh), using density functional theory based methods. We find that the best non-magnetic analog for the subtraction depends on the magnetic material and on the range of temperatures. While the phonon specific heat contribution of YRhIn 5 is an excellent approximation to the one of GdCoIn 5 in the full temperature range, for GdRhIn 5 we find a better agreement with LaCoIn 5 , in both cases, as a result of an optimum compensation effect between masses and volumes. We present measurements of the specific heat of the compounds GdMIn 5 (M=Co, Rh) up to room temperature where it surpasses the value expected from the Dulong–Petit law. We obtain a good agreement between theory and experiment when we include anharmonic effects in the calculations.

  12. Lattice specific heat for the RMIn{sub 5} (R=Gd, La, Y; M=Co, Rh) compounds: Non-magnetic contribution subtraction

    Energy Technology Data Exchange (ETDEWEB)

    Facio, Jorge I., E-mail: jorge.facio@cab.cnea.gov.ar [Centro Atómico Bariloche and Instituto Balseiro, CNEA, 8400 Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Betancourth, D.; Cejas Bolecek, N.R. [Centro Atómico Bariloche and Instituto Balseiro, CNEA, 8400 Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Jorge, G.A. [Instituto de Ciencias, Universidad Nacional de General Sarmiento, Buenos Aires (Argentina); Pedrazzini, Pablo; Correa, V.F.; Cornaglia, Pablo S. [Centro Atómico Bariloche and Instituto Balseiro, CNEA, 8400 Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); Vildosola, V. [Centro Atómico Constituyentes, CNEA, 1650 San Martín, Buenos Aires (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina); García, D.J. [Centro Atómico Bariloche and Instituto Balseiro, CNEA, 8400 Bariloche (Argentina); Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) (Argentina)

    2016-06-01

    We analyze theoretically a common experimental process used to obtain the magnetic contribution to the specific heat of a given magnetic material. In the procedure, the specific heat of a non-magnetic analog is measured and used to subtract the non-magnetic contributions, which are generally dominated by the lattice degrees of freedom in a wide range of temperatures. We calculate the lattice contribution to the specific heat for the magnetic compounds GdMIn{sub 5} (M=Co, Rh) and for the non-magnetic YMIn{sub 5} and LaMIn{sub 5} (M=Co, Rh), using density functional theory based methods. We find that the best non-magnetic analog for the subtraction depends on the magnetic material and on the range of temperatures. While the phonon specific heat contribution of YRhIn{sub 5} is an excellent approximation to the one of GdCoIn{sub 5} in the full temperature range, for GdRhIn{sub 5} we find a better agreement with LaCoIn{sub 5}, in both cases, as a result of an optimum compensation effect between masses and volumes. We present measurements of the specific heat of the compounds GdMIn{sub 5} (M=Co, Rh) up to room temperature where it surpasses the value expected from the Dulong–Petit law. We obtain a good agreement between theory and experiment when we include anharmonic effects in the calculations.

  13. Magnetization, resistivity, specific heat and ab initio calculations of Gd5Sb3.

    Science.gov (United States)

    Samatham, S Shanmukharao; Patel, Akhilesh Kumar; Lukoyanov, Alexey V; Suresh, K G

    2018-06-07

    We report on the combined results of structural, magnetic, transport and calorimetric properties of Mn5Si3-type hexagonal Gd5Sb3, together with ab-initio calculations. It exhibits a ferromagnetic (FM)-like transition at 265 K, antiferromagnetic (AFM) Néel transition at 95.5 K followed by a spin-orientation transition at 62 K. The system is found to be in AFM state down to 2 K in a field of 70 kOe. The FM-AFM phase coexistence is not noticeable despite large positive Curie-Weiss temperature (θCW = 223.5 ± 0.2 K). Instead, low-temperature AFM and high-temperature FM-like phases are separated in large temperatures. Temperature-magnetic field (H-T) phase diagram reveals field-driven complex magnetic phases. Within the AFM phase, the system is observed to undergo field-driven spin-orientation transitions. Field-induced tricritical and quantum critical points appear to be absent due to strong AFM nature and by the intervention of FM-like state between paramagnetic and AFM states, respectively. The metallic behavior of the compound is inferred from resistivity along with large Sommerfeld parameter. However, no sign of strong electron-correlations is reasoned from the Kadowaki-Wood's ratio A2 ∼ 1.9×10-6 μΩ.cm.(mol.K)2(mJ)-2, despite heavy γ. Essentially, ab initio calculations accounting for electronic correlations confirm AFM nature of low-temperature magnetic state in Gd5Sb3 and attainable FM ordering in agreement with experimental data. © 2018 IOP Publishing Ltd.

  14. Indication for a chiral phase in the molecular magnetic chain Gd(hfac)3NiTiPr by specific heat and μ+SR measurements

    International Nuclear Information System (INIS)

    Lascialfari, A.; Ullu, R.; Affronte, M.; Cinti, F.; Caneschi, A.; Gatteschi, D.; Rovai, D.; Pini, M.G.; Rettori, A.

    2004-01-01

    Specific heat and muon spin relaxation (μ + SR) measurements performed in the molecular magnetic chain Gd(hfac) 3 NiTiPr provide indication for the onset, at T 0 =2.08 K, of a phase with chiral order in the absence of long-range helical order. Specific heat data (probing the chirality-chirality correlation function) show a peak at T 0 that disappears upon application of a 5 T magnetic field, while μ + SR data (probing the spin-spin correlation function) do not present any anomaly at T 0 nor oscillations in the asymmetry curve below T 0

  15. The low temperature specific heat and electrical transport, magnetic properties of Pr{sub 0.65}Ca{sub 0.35}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Han, Zhiyong, E-mail: zyhan@cauc.edu.cn

    2017-02-01

    The magnetic properties, electrical transport properties, and low temperature specific heat of polycrystalline perovskite manganese oxide Pr{sub 0.65}Ca{sub 0.35}MnO{sub 3} have been investigated experimentally. It is found that there exists cluster glass state in the sample at low temperature besides the antiferromagnetic insulating state. With the increase of magnetic field, antiferromagnetic insulating state converts to ferromagnetic metal state and the Debye temperature decreases gradually. In addition, the low temperature electron specific heat in zero magnetic field is obviously larger than that of ordinary rare-earth manganites oxide and this phenomenon is related to the itinerant electrons in ferromagnetic cluster state and the disorder in Pr{sub 0.65}Ca{sub 0.35}MnO{sub 3}. - Highlights: • There exists cluster glass state in the sample at low temperature besides the antiferromagnetic insulating state. • With the increase of magnetic field, antiferromagnetic insulating state converts to ferromagnetic metal state. • Low temperature electron specific heat in zero magnetic field is larger than that of ordinary rare-earth manganites oxide.

  16. Absence of a long-range ordered magnetic ground state in Pr3Rh4Sn13 studied through specific heat and inelastic neutron scattering

    Science.gov (United States)

    Nair, Harikrishnan S.; Ogunbunmi, Michael O.; Ghosh, S. K.; Adroja, D. T.; Koza, M. M.; Guidi, T.; Strydom, A. M.

    2018-04-01

    Signatures of absence of a long-range ordered magnetic ground state down to 0.36 K are observed in magnetic susceptibility, specific heat, thermal/electrical transport and inelastic neutron scattering data of the quasi-skutterudite compound Pr3Rh4Sn13 which crystallizes in the Yb3Rh4Sn13-type structure with a cage-like network of Sn atoms. In this structure, Pr3+ occupies a lattice site with D 2d point symmetry having a ninefold degeneracy corresponding to J  =  4. The magnetic susceptibility of Pr3Rh4Sn13 shows only a weak temperature dependence below 10 K otherwise remaining paramagnetic-like in the range, 10 K-300 K. From the inelastic neutron scattering intensity of Pr3Rh4Sn13 recorded at different temperatures, we identify excitations at 4.5(7) K, 5.42(6) K, 10.77(5) K, 27.27(5) K, 192.28(4) K and 308.33(3) K through a careful peak analysis. However, no signatures of long-range magnetic order are observed in the neutron data down to 1.5 K, which is also confirmed by the specific heat data down to 0.36 K. A broad Schottky-like peak is recovered for the magnetic part of the specific heat, C 4f, which suggests the role of crystal electric fields of Pr3+ . A crystalline electric field model consisting of 7 levels was applied to C 4f which leads to the estimation of energy levels at 4.48(2) K, 6.94(4) K, 11.23(8) K, 27.01(5) K, 193.12(6) K and 367.30(2) K. The CEF energy levels estimated from the heat capacity analysis are in close agreement with the excitation energies seen in the neutron data. The Sommerfeld coefficient estimated from the analysis of magnetic specific heat is γ = 761(6) mJ K-2 mol-Pr which suggests the formation of heavy itinerant quasi-particles in Pr3Rh4Sn13. Combining inelastic neutron scattering results, analysis of the specific heat data down to 0.36 K, magnetic susceptibility and, electrical and thermal transport, we establish the absence of long-range ordered magnetic ground state in Pr3Rh4Sn13.

  17. Magnetic heating in the sun

    International Nuclear Information System (INIS)

    Chiuderi, C.

    1981-01-01

    The observational evidence for magnetic heating in the solar corona is presented. The possible ways of investigating theoretically the nature of the heating processes are critically discussed. Merits and disadvantages of the basic mechanisms so far proposed are reviewed. Finally, a preliminary application of the magnetic heating concept to stellar coronae is presented. (orig.)

  18. Indication for a chiral phase in the molecular magnetic chain Gd(hfac){sub 3}NiTiPr by specific heat and {mu}{sup +}SR measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lascialfari, A.; Ullu, R.; Affronte, M.; Cinti, F.; Caneschi, A.; Gatteschi, D.; Rovai, D.; Pini, M.G. E-mail: mgpini@ifac.cnr.it; Rettori, A

    2004-05-01

    Specific heat and muon spin relaxation ({mu}{sup +}SR) measurements performed in the molecular magnetic chain Gd(hfac){sub 3}NiTiPr provide indication for the onset, at T{sub 0}=2.08 K, of a phase with chiral order in the absence of long-range helical order. Specific heat data (probing the chirality-chirality correlation function) show a peak at T{sub 0} that disappears upon application of a 5 T magnetic field, while {mu}{sup +}SR data (probing the spin-spin correlation function) do not present any anomaly at T{sub 0} nor oscillations in the asymmetry curve below T{sub 0}.

  19. Evidence for a helical and a chiral phase transition in the Gd(hfac)3NITiPr magnetic specific heat

    International Nuclear Information System (INIS)

    Cinti, F.; Rettori, A.; Barucci, M.; Olivieri, E.; Risegari, L.; Ventura, G.; Caneschi, A.; Gatteschi, D.; Rovai, D.; Pini, M.G.; Affronte, M.; Mariani, M.; Lascialfari, A.

    2007-01-01

    New specific heat data taken at very low temperatures (0.03 3 NITiPr show a clear λ anomaly at T N =0.039K signaling the onset of the 3D helimagnetic phase. They match fairly well with previously reported data which showed the onset of the chiral phase transition at T 0 =2.08K. Also new magnetic susceptibility data taken in the neighborhood at T 0 are repeated

  20. Dualism of the 5f electrons of the ferromagnetic superconductor UGe2 as seen in magnetic, transport, and specific-heat data

    Science.gov (United States)

    Troć, R.; Gajek, Z.; Pikul, A.

    2012-12-01

    Single-crystalline UGe2 was investigated by means of magnetic susceptibility, magnetization, electrical resistivity, magnetoresistivity, and specific-heat measurements, all carried out in wide temperature and magnetic-field ranges. An analysis of the obtained data points out the dual behavior of the 5f electrons in this compound, i.e., possessing simultaneously local and itinerant characters in two substates. The magnetic and thermal characteristics of the compound were modeled using the effective crystal field (CF) in the intermediate coupling scheme and initial parameters obtained in the angular overlap model. Various configurations of the localized 5fn (n = 1, 2, and 3) electrons on the uranium ion have been probed. The best results were obtained for the 5f2 (U4+) configuration. The CF parameters obtained in the paramagnetic region allowed us to reproduce satisfactorily the experimental findings in the whole temperature range including also the magnitude of the ordered magnetic moment of uranium at low temperature. The electrical resistivity data after subtraction of the phonon contribution reveal the presence of a Kondo-like interaction in UGe2 supporting the idea of partial localization of the 5f electrons in UGe2. On the other hand, magnetoresistivity and an excess of specific heat originated from the hybridized (itinerant) part of 5f states, apparent around the characteristic temperature T*, give a distinct signature for the presence of the coupled charge-density wave and spin-density wave fluctuations over all the ferromagnetic region with a maximum at T*, postulated earlier in the literature.

  1. Evidence for a helical and a chiral phase transition in the Gd(hfac){sub 3}NITiPr magnetic specific heat

    Energy Technology Data Exchange (ETDEWEB)

    Cinti, F. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy)]. E-mail: fabio.cinti@fi.infn.it; Rettori, A. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy); Barucci, M. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy); Olivieri, E. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy); Risegari, L. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy); Ventura, G. [INFM and Department of Physics, University of Florence, 50019 Sesto Fiorentino (Italy); Caneschi, A. [Department of Inorganic Chemistry, University of Florence, 50019 Sesto Fiorentino (Italy); Gatteschi, D. [Department of Inorganic Chemistry, University of Florence, 50019 Sesto Fiorentino (Italy); Rovai, D. [Department of Inorganic Chemistry, University of Florence, 50019 Sesto Fiorentino (Italy); Pini, M.G. [ISC-CNR, 50019 Sesto Fiorentino (Italy); Affronte, M. [INFM-S3 and Department of Physics, University of Modena, 41100 Modena (Italy); Mariani, M. [INFM and Department of Physics, University of Pavia, 27100 Pavia (Italy); Lascialfari, A. [Istituto di Fisiologia e Chimica Biologica, University of Milano, Milano (Italy); INFM and Department of Physics, University of Pavia, 27100 Pavia (Italy)

    2007-03-15

    New specific heat data taken at very low temperatures (0.03magnetic susceptibility data taken in the neighborhood at T{sub 0} are repeated.

  2. Magnetic heat pump flow director

    Science.gov (United States)

    Howard, Frank S. (Inventor)

    1995-01-01

    A fluid flow director is disclosed. The director comprises a handle body and combed-teeth extending from one side of the body. The body can be formed of a clear plastic such as acrylic. The director can be used with heat exchangers such as a magnetic heat pump and can minimize the undesired mixing of fluid flows. The types of heat exchangers can encompass both heat pumps and refrigerators. The director can adjust the fluid flow of liquid or gas along desired flow directions. A method of applying the flow director within a magnetic heat pump application is also disclosed where the comb-teeth portions of the director are inserted into the fluid flow paths of the heat pump.

  3. Magnetic Heat Pump Containing Flow Diverters

    Science.gov (United States)

    Howard, Frank S.

    1995-01-01

    Proposed magnetic heat pump contains flow diverters for suppression of undesired flows. If left unchecked, undesired flows mix substantial amounts of partially heated and partially cooled portions of working fluid, effectively causing leakage of heat from heated side to cooled side. By reducing leakage of heat, flow diverters increase energy efficiency of magnetic heat pump, potentially offering efficiency greater than compressor-driven refrigerator.

  4. The Nd-Mn exchange interaction, low temperature specific heat and magnetism of Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Beznosov, Anatoly [B. Verkin Institute for Low Temperature Physics and Engineering NASU, 47 Lenin Avenue, Kharkov 61103 (Ukraine); Fertman, Elena, E-mail: fertman@ilt.kharkov.ua [B. Verkin Institute for Low Temperature Physics and Engineering NASU, 47 Lenin Avenue, Kharkov 61103 (Ukraine); Desnenko, Vladimir [B. Verkin Institute for Low Temperature Physics and Engineering NASU, 47 Lenin Avenue, Kharkov 61103 (Ukraine); Kajnakova, Marcela; Feher, Alexander [Centre of Low Temperature Physics of the Faculty of Science UPJS and IEP SAS, Park Angelinum 9, 04154 Kosice (Slovakia)

    2011-10-15

    The low temperature specific heat and magnetic characteristics of Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3} perovskite are studied in a wide range of magnetic fields (up to 9 T). Temperature dependent specific heat data show a broadened Schottky-like anomaly below 20 K caused by splitting of the Nd{sup 3+} ions ground-state doublet in the effective molecular field H{sub ex}, determined by exchange interaction between Nd and Mn spin systems supplemented by an applied external magnetic field. Existence of the splitting at zero magnetic field and expressed field dependence is the evidence of a strong exchange coupling between Nd and Mn magnetic subsystems. The Nd-ions magnetic ordering leads to an additional contribution to the magnetic moment of the system below 30 K, producing anomalies of the magnetic loss and field-cooled and zero-field-cooled magnetizations. The observed broadened Schottky-like anomalies are fitted for each applied magnetic field by the sum of three Schottky functions. Applied magnetic field extends the anomaly region and shifts it to higher temperatures. Splitting of the higher crystal field Kramers doublets gives an additional contribution to the heat capacity in magnetic fields. The ground state doublet g-factors g{sub ||} and g{sub perpendicular} were estimated to be 3.4 and 2.2, respectively, and H{sub ex} was estimated to be 9 T. The Nd{sup 3+} ions magnetic moment estimated from the magnetization data agrees with the value obtained from the specific heat data. - Highlights: > Low temperature specific heat of Nd{sub 2/3}Ca{sub 1/3}MnO{sub 3} has been measured in magnetic fields up to 9 T. > Schottky-like anomalies are fitted for each magnetic field by a sum of three Schottky functions. > An effective magnetic field of the Mn spin system on Nd ion has been estimated as H{sub ex}=9 T. > Nd{sup 3+} ground-state g-factors have been estimated as g{sub ||}=3.4 and g{sub perpendicular} =2.2. > Magnetic ordering of the Nd subsystem has been revealed below

  5. Numerical routine for magnetic heat pump cascading

    DEFF Research Database (Denmark)

    Filonenko, Konstantin; Lei, Tian; Engelbrecht, Kurt

    Heat pumps use low-temperature heat absorbed from the energy source to create temperature gradient (TG) across the energy sink. Magnetic heat pumps (MHP) can perform this function through operating active magnetic regeneration (AMR) cycle. For building heating, TGs of up to a few K might...

  6. Measurement of low-temperature specific heat

    International Nuclear Information System (INIS)

    Stewart, G.R.

    1983-01-01

    The measurement of low-temperature specific heat (LTSH) (0.1 K< T<60 K) has seen a number of breakthroughs both in design concepts and instrumentation in the last 15 years: particularly in small sample calorimetry. This review attempts to provide an overview of both large and small sample calorimetry techniques at temperatures below 60 K, with sufficient references to enable more detailed study. A comprehensive review is made of the most reliable measurements of the LTSH of 84 of the elements to illustrate briefly some of the problems of measurements and analysis, as well as to provide additional references. More detail is devoted to three special areas of low-temperature calorimetry that have seen rapid development recently: (1) measurement of the specific heat of highly radioactive samples, (2) measurement of the specific heat of materials in high magnetic fields (18 T), and (3) measurement of the specific heat of very small (100 μg) samples. The review ends with a brief discussion of the frontier research currently underway on microcalorimetry for nanogram sample weights

  7. Reversible and irreversible magnetocaloric effect in the NdBa{sub 2}Cu{sub 3}O{sub 7} superconductor in relation to specific heat and magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Plackowski, T [Departement de Physique de la Matiere Condensee, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Institute of Low Temperature and Structure Research, ulica Okolna 2, 50-422 Wroclaw (Poland); Wang, Y [Departement de Physique de la Matiere Condensee, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Lortz, R [Departement de Physique de la Matiere Condensee, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Junod, A [Departement de Physique de la Matiere Condensee, Universite de Geneve, CH-1211 Geneva 4 (Switzerland); Wolf, Th [Forschungszentrum Karlsruhe, Institut fuer Technische Physik, Postfach 3640, D-76021Karlsruhe (Germany)

    2005-11-02

    A recently developed technique for measuring the isothermal magnetocaloric coefficient (M{sub T}) is applied to the study of a superconducting NdBa{sub 2}Cu{sub 3}O{sub 7} single crystal. Results are compared with magnetization (M) and specific heat (C). In the reversible region both C and M{sub T} follow the scaling law of the 3D-xy universality class. The anomalies connected with flux-line lattice melting are visible on M{sub T}(B) curves as peaks and steps, similar to C(T) curves yet with much smaller background. At lower temperature, in the irreversible region the M{sub T}(B) behaviour resembles more that of M(B), exhibiting the 'fishtail' effect. Our results confirm that the peculiarities of the phase diagram known from the high-temperature superconductor YBa{sub 2}Cu{sub 3}O{sub 7}, e.g. vortex melting, dominance of critical fluctuations and absence of a B{sub c2} critical field line, are a common property of RE-123 systems.

  8. A review of magnetic heat pump technology

    International Nuclear Information System (INIS)

    Barclay, J.A.

    1990-01-01

    The area of technology classified as heat pumps generally refers to refrigerators, heat pumps and heat engines. This review is restricted to the literature on magnetic refrigerators and magnetic heat pumps which are referred to interchangeably. Significant progress has been made on the development of engineering prototypes of cryogenic, nonregenerative magnetic refrigerators utilizing conductive heat transfer in the 0.1 K to 20 K temperature range. Advances have also been made in analysis of regenerative magnetic refrigerators and heat pumps utilizing the active magnetic regeneration (AMR) concept. Units based on AMR are being modeled, designed and/or built to operate in various temperature ranges including 1.8-4.5 K, 4-15 K, 15-85 K, and 270-320 K. The near room temperature units have been scaled to 50 kW as both refrigerators and heat pumps. The progress of magnetic refrigeration over the last three years is summarized and discussed

  9. The magnetic fluid for heat transfer applications

    International Nuclear Information System (INIS)

    Nakatsuka, K.; Jeyadevan, B.; Neveu, S.; Koganezawa, H.

    2002-01-01

    Real-time visual observation of boiling water-based and ionic magnetic fluids (MFs) and heat transfer characteristics in heat pipe using ionic MF stabilized by citrate ions (JC-1) as working liquid are reported. Irrespective of the presence or absence of magnetic field water-based MF degraded during boiling. However, the degradation of JC-1 was avoided by heating the fluid in magnetic field. Furthermore, the heat transfer capacity of JC-1 heat pipe under applied magnetic field was enhanced over the no field case

  10. Specific heat of ZnCoSe semimagnetic semiconductor

    NARCIS (Netherlands)

    Twardowski, A.; Swagten, H.J.M.; Jonge, de W.J.M.; Demianiuk, M.

    1990-01-01

    The magnetic specific heat of ZnCoSe data are reported in the temperature range 1.5 magnetic field B <3 T. The experimental data are interpreted in the Extended Nearest Neighbour Pair Approximation taking into account short and long ranged d-d exchange interaction.

  11. Development of heat-resistant magnetic sensor

    International Nuclear Information System (INIS)

    Takaya, Shigeru; Arakawa, Hisashi; Keyakida, Satoshi

    2013-01-01

    A heat-resistant flux gate magnetic sensor has been developed. Permendur, which has high Curie point, is employed as the magnetic core material and the detection method of the external magnetic field is modified. The characteristics of the developed magnetic sensor up to 500degC were evaluated. The sensor output increased linearly with the external magnetic field in the range of ±5 G and the standard deviation at 500degC was about 0.85G. (author)

  12. Numerical routine for magnetic heat pump cascading

    DEFF Research Database (Denmark)

    Filonenko, Konstantin; Lei, Tian; Engelbrecht, Kurt

    Heat pumps use low-temperature heat absorbed from the energy source to create temperature gradient (TG) across the energy sink. Magnetic heat pumps (MHP) can perform this function through operating active magnetic regeneration (AMR) cycle. For building heating, TGs of up to a few K might...... and 3 K. Changing the number of MHPs, we optimized input parameters to achieve maximum heating powers. We have found that both maximum heating power and COP decrease together with number of heat pumps, but the TGs and the temperature span can be largely increased. References [1] M. Tahavori et al., “A...... be necessary, which is hardly achievable with a single MHP and such techniques as cascading are required. Series and parallel cascading increase the AMR span and heating power, respectively, but do not change TG. Therefore, the intermediate type of cascading was proposed with individual MHPs separately...

  13. Practical and efficient magnetic heat pump

    Science.gov (United States)

    Brown, G. V.

    1978-01-01

    Method for pumping heat magnetically at room temperature is more economical than existing refrigeration systems. Method uses natural magneto-thermal effect of gadolinium metal to establish temperature gradient across length of tube. Regenerative cyclic process in which gadolinium sample is magnetized and gives off heat at one end of tube, and then is demagnetized at other end to absorb heat has established temperature gradients of 144 degrees F in experiments near room temperature. Other materials with large magnetothermal effects can be used below room temperature. Possible commercial applications include freeze-drying and food processing, cold storage, and heating and cooling of buildings, plants, and ships.

  14. Electrospun magnetic nanofibre mats – A new bondable biomaterial using remotely activated magnetic heating

    Energy Technology Data Exchange (ETDEWEB)

    Zhong, Yi [Department of Materials Engineering, University of British Columbia, Vancouver (Canada); Key Laboratory of Science & Technology of Eco-Textile, Ministry of Education, College of Chemistry, Chemical Engineering and Biotechnology, Donghua University, Shanghai (China); Leung, Victor; Yuqin Wan, Lynn [Department of Materials Engineering, University of British Columbia, Vancouver (Canada); Dutz, Silvio [Institut für Biomedizinische Technik und Informatik, Technische Universität Ilmenau (Germany); Department of Nano Biophotonics, Leibniz Institute of Photonic Technology, Jena (Germany); Ko, Frank K., E-mail: frank.ko@ubc.ca [Department of Materials Engineering, University of British Columbia, Vancouver (Canada); Häfeli, Urs O., E-mail: urs.hafeli@ubc.ca [Faculty of Pharmaceutical Sciences, University of British Columbia, Vancouver (Canada)

    2015-04-15

    A solvothermal process was adopted to produce hydrophilic magnetite (Fe{sub 3}O{sub 4}) nanoparticles which were subsequently emulsified with a chloroform/methanol (70/30 v/v) solution of poly(caprolactone) (PCL) and then electrospun into a 0.2 mm thick PCL mat. The magnetic heating of the mats at a field amplitude of 25 kA/m and frequency of 400 kHz exhibited promising efficiency for magnetic hyperthermia, with a specific absorption rate of about 40 W/g for the magnetic mat. The produced heat was used to melt the magnetic mat onto the surrounding non-magnetic polymer mat from within, without destroying the nanostructure of the non-magnetic polymer more than 0.5 mm away. Magnetic nanofibre mats might thus be useful for internal heat sealing applications, and potentially also for thermotherapy.

  15. Transient Analysis of a Magnetic Heat Pump

    Science.gov (United States)

    Schroeder, E. A.

    1985-01-01

    An experimental heat pump that uses a rare earth element as the refrigerant is modeled using NASTRAN. The refrigerant is a ferromagnetic metal whose temperature rises when a magnetic field is applied and falls when the magnetic field is removed. The heat pump is used as a refrigerator to remove heat from a reservoir and discharge it through a heat exchanger. In the NASTRAN model the components modeled are represented by one-dimensional ROD elements. Heat flow in the solids and fluid are analyzed. The problem is mildly nonlinear since the heat capacity of the refrigerant is temperature-dependent. One simulation run consists of a series of transient analyses, each representing one stroke of the heat pump. An auxiliary program was written that uses the results of one NASTRAN analysis to generate data for the next NASTRAN analysis.

  16. Specific heats of degenerate ideal gases

    OpenAIRE

    Caruso, Francisco; Oguri, Vitor; Silveira, Felipe

    2017-01-01

    From arguments based on Heisenberg's uncertainty principle and Pauli's exclusion principle, the molar specific heats of degenerate ideal gases at low temperatures are estimated, giving rise to values consistent with the Nerst-Planck Principle (third law of Thermodynamics). The Bose-Einstein condensation phenomenon based on the behavior of specific heat of massive and non-relativistic boson gases is also presented.

  17. Magnetic induced heating of nanoparticle solutions

    Energy Technology Data Exchange (ETDEWEB)

    Murph, S. Hunyadi [Savannah River Site (SRS), Aiken, SC (United States); Univ. of Georgia, Athens, GA (United States); Brown, M. [Savannah River Site (SRS), Aiken, SC (United States); Coopersmith, K. [Savannah River Site (SRS), Aiken, SC (United States); Fulmer, S. [Savannah River Site (SRS), Aiken, SC (United States); Sessions, H. [Savannah River Site (SRS), Aiken, SC (United States); Ali, M. [Univ. of South Carolina, Columbia, SC (United States)

    2016-12-02

    Magnetic induced heating of nanoparticles (NP) provides a useful advantage for many energy transfer applications. This study aims to gain an understanding of the key parameters responsible for maximizing the energy transfer leading to nanoparticle heating through the use of simulations and experimental results. It was found that magnetic field strength, NP concentration, NP composition, and coil size can be controlled to generate accurate temperature profiles in NP aqueous solutions.

  18. Nanoscale magnetic heat pumps and engines

    NARCIS (Netherlands)

    Bauer, G.E.W.; Bretzel, S.; Brataas, A.; Tserkovnyak, Y.

    2010-01-01

    We present the linear-response matrix for a sliding domain wall in a rotatable magnetic nanowire, which is driven out of equilibrium by temperature and voltage bias, mechanical torque, and magnetic field. An expression for heat-current-induced domain-wall motion is derived. Application of Onsager’s

  19. Essential Specification Elements for Heat Exchanger Replacement

    Energy Technology Data Exchange (ETDEWEB)

    Bower, L.

    2015-07-01

    Performance upgrade and equipment degradation are the primary impetuses for a nuclear power plant to engage in the large capital cost project of heat exchanger replacement. Along with attention to these issues, consideration of heat exchanger Codes and Standards, material improvements, thermal redesign, and configuration are essential for developing User’s Design Specifications for successful replacement projects. The User’s Design Specification is the central document in procuring ASME heat exchangers. Properly stated objectives for the heat exchanger replacement are essential for obtaining the materials, configurations and thermal designs best suited for the nuclear power plant. Additionally, the code of construction required and the applied manufacturing standard (TEMA or HEI) affects how the heat exchanger may be designed or configured to meet the replacement goals. Knowledge of how Codes and Standards affect design and configuration details will aid in writing the User’s Design Specification. Joseph Oat Corporation has designed and fabricated many replacement heat exchangers for the nuclear power industry. These heat exchangers have been constructed per ASME Section III to various Code-Years or ASME Section VIII-1 to the current Code-Year also in accordance with TEMA and HEI. These heat exchangers have been a range of like-for-like replacement to complete thermal, material and configuration redesigns. Several examples of these heat exchangers with their Code, Standard and specification implications are presented. (Author.

  20. Heat transfer in a magnet C

    International Nuclear Information System (INIS)

    Sircilli Neto, F.; Passaro, A.; Borges, E.M.

    1991-01-01

    The cooling systems of nuclear reactors for spacial applications include direct current electromagnetic pumps, which are used to circulate the coolant fluid thru the reactor core. In this work, the transfer of the heat generated by the electrical current in a magnet C excitation coils, which is used in a prototype pump, was evaluated. Considering the processes of heat transfer by conduction, natural convection and radiation, the results of simulation with the codes HEATING5 and AUTHEATS indicate the utilization of the 180 sup(0)C thermal class conductor for a working Joule power of 4 10 sup(4) W/m sup(3) in each magnet coil. (author)

  1. From a magnet to a heat pump

    DEFF Research Database (Denmark)

    Navickaité, Kristina; Neves Bez, Henrique; Engelbrecht, Kurt

    2016-01-01

    The magnetocaloric effect (MCE) is the thermal response of a magnetic material to an applied magnetic field. Magnetic cooling is a promising alternative to conventional vapor compression technology in near room temperature applications and has experienced significant developments over the last five...... years. Although further improvements are necessary before the technology can be commercialized. Researchers were mainly focused on the development of materials and optimization of a flow system in order to increase the efficiency of magnetic heat pumps. The project, presented in this paper, is devoted...... to the improvement of heat pump and cooling technologies through simple tests of prospective regenerator designs. A brief literature review and expected results are presented in the paper. It is mainly focused on MCE technologies and provides a brief introduction to the magnetic cooling as an alternative...

  2. Characterization of quasi-one-dimensional S=1/2 Heisenberg antiferromagnets Sr2Cu(PO4)2 and Ba2Cu(PO4)2 with magnetic susceptibility, specific heat, and thermal analysis

    International Nuclear Information System (INIS)

    Belik, A.A.; Azuma, M.; Takano, M.

    2004-01-01

    Properties of Sr 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 having [Cu(PO 4 ) 2 ] ∞ linear chains in their structures with Cu-O-P-O-Cu linkages were studied by magnetic susceptibility (T=2-400 K, H=100 Oe) and specific heat measurements (T=0.45-21 K). Magnetic susceptibility versus temperature curves, χ(T), showed broad maxima at T M =92 K for Sr 2 Cu(PO 4 ) 2 and T M =82 K for Ba 2 Cu(PO 4 ) 2 characteristic of quasi-one-dimensional systems. The χ(T) data were excellently fitted by the spin susceptibility curve for the uniform S=1/2 chain (plus temperature-independent and Curie-Weiss terms) with g=2.153(4) and J/k B =143.6(2) K for Sr 2 Cu(PO 4 ) 2 and g=2.073(4) and J/k B =132.16(9) K for Ba 2 Cu(PO 4 ) 2 (Hamiltonian H=JΣS i S i+1 ). The similar J/k B values were obtained from the specific heat data. No anomaly was observed on the specific heat from 0.45 to 21 K for both compounds indicating that the temperatures of long-range magnetic ordering, T N , were below 0.45 K. Sr 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 are an excellent physical realization of the S=1/2 linear chain Heisenberg antiferromagnet with k B T N /J 2 CuO 3 (k B T N /J∼0.25%) and γ-LiV 2 O 5 (k B T N /J 2 Cu(PO 4 ) 2 and Ba 2 Cu(PO 4 ) 2 were stable in air up to 1280 and 1150 K, respectively

  3. Interpretation of specific-heat and spontaneous-magnetization anomalies at the reentrant superconducting - ferromagnetic transition in (Ho0.6Er0.4)Rh4B4

    International Nuclear Information System (INIS)

    Woolf, L.D.; Johnston, D.C.; Mook, H.A.; Koehler, W.C.; Maple, M.B.; Fisk, Z.

    1981-09-01

    Analysis of neutron-diffraction data on the compound (Ho 0 . 6 Er 0 . 4 )Rh 4 B 4 indicates that the Curie temperature is depressed by about 0.2 K due to the occurrence of superconductivity, in agreement with theoretical predictions. The temperature dependence of the specific heat in the vicinity of the first-order reentrant superconducting - ferromagnetic transition was computed by means of a simple model from the temperature dependence of the spontaneous magnetization of the Ho ions and was found to be in good agreement with the experimental data

  4. Threshold heating temperature for magnetic hyperthermia: Controlling the heat exchange with the blocking temperature of magnetic nanoparticles

    Science.gov (United States)

    Pimentel, B.; Caraballo-Vivas, R. J.; Checca, N. R.; Zverev, V. I.; Salakhova, R. T.; Makarova, L. A.; Pyatakov, A. P.; Perov, N. S.; Tishin, A. M.; Shtil, A. A.; Rossi, A. L.; Reis, M. S.

    2018-04-01

    La0.75Sr0.25MnO3 nanoparticles with average diameter close to 20.9 nm were synthesized using a sol-gel method. Measurements showed that the heating process stops at the blocking temperaturesignificantly below the Curie temperature. Measurements of Specific Absorption Rate (SAR) as a function of AC magnetic field revealed a superquadratic power law, indicating that, in addition to usual Néel and Brown relaxation, the hysteresis also plays an important role in the mechanism of heating. The ability to control the threshold heating temperature, a low remanent magnetization and a low field needed to achieve the magnetic saturation are the advantages of this material for therapeutic magnetic hyperthermia.

  5. Magnetic heat pumping near room temperature

    Science.gov (United States)

    Brown, G. V.

    1976-01-01

    It is shown that magnetic heat pumping can be made practical at room temperature by using a ferromagnetic material with a Curie point at or near operating temperature and an appropriate regenerative thermodynamic cycle. Measurements are performed which show that gadolinium is a resonable working material and it is found that the application of a 7-T magnetic field to gadolinium at the Curie point (293 K) causes a heat release of 4 kJ/kg under isothermal conditions or a temperature rise of 14 K under adiabatic conditions. A regeneration technique can be used to lift the load of the lattice and electronic heat capacities off the magnetic system in order to span a reasonable temperature difference and to pump as much entropy per cycle as possible

  6. Numerical simulation of magnetic heat pumps

    International Nuclear Information System (INIS)

    Smaili, A.; Masson, C.

    2002-01-01

    This article presents a numerical method for performance predictions of magnetic heat pump (MHP) devices. Such devices consist primarily of a magnetic regenerator (solid refrigerant media) and circulating fluid. Unlike conventional gas-cycles, MHP devices function according to thermomagnetic cycles which do not require neither compressor nor expander. In this paper, the flow field throughout the regenerator is described by continuity and unsteady incompressible Navier-Stokes equations. The heat transfer between fluid and solid is introduced by considering the corresponding energy equations. The proposed mathematical model has been solved using a control volume finite element method. The fully implicit scheme is used for time discretization. Simulation results including heating capacity and coefficient of performance are presented for a given MHP cycle. Mainly, the effects of cycle frequency, mass flow rate and the magnetic regenerator mass are investigated. (author)

  7. Plasma heating in a variable magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kichigin, G. N., E-mail: king@iszf.irk.ru [Russian Academy of Sciences, Institute of Solar-Terrestrial Physics (Russian Federation)

    2013-05-15

    The problem of particle acceleration in a periodically variable magnetic field that either takes a zero value or passes through zero is considered. It is shown that, each time the field [0]passes through zero, the particle energy increases abruptly. This process can be regarded as heating in the course of which plasma particles acquire significant energy within one field period. This mechanism of plasma heating takes place in the absence of collisions between plasma particles and is analogous to the mechanism of magnetic pumping in collisional plasma considered by Alfven.

  8. Lubricant reflow after laser heating in heat assisted magnetic recording

    Science.gov (United States)

    Wu, Haoyu; Mendez, Alejandro Rodriguez; Xiong, Shaomin; Bogy, David B.

    2015-05-01

    In heat assisted magnetic recording (HAMR) technology for hard disk drives, the media will be heated to about 500 °C during the writing process in order to reduce its magnetic coercivity and thus allow data writing with the magnetic head transducers. The traditional lubricants such as Z-dol and Z-tetraol may not be able to perform in such harsh heating conditions due to evaporation, decomposition and thermal depletion. However, some of the lubricant depletion can be recovered due to reflow after a period of time, which can help to reduce the chance of head disk interface failure. In this study, experiments of lubricant thermal depletion and reflow were performed using a HAMR test stage for a Z-tetraol type lubricant. Various lubricant depletion profiles were generated using different laser heating conditions. The lubricant reflow process after thermal depletion was monitored by use of an optical surface analyzer. In addition, a continuum based lubrication model was developed to simulate the lubricant reflow process. Reasonably good agreement between simulations and experiments was achieved.

  9. Magnetization and specific heat study of metamagnetism in Lu.sub.2./sub.Fe.sub.17./sub.-based intermetallic compounds

    Czech Academy of Sciences Publication Activity Database

    Tereshina, Evgeniya; Andreev, Alexander V.

    2010-01-01

    Roč. 18, č. 6 (2010), 1205-1210 ISSN 0966-9795 R&D Projects: GA ČR GA202/09/0339 Institutional research plan: CEZ:AV0Z10100520 Keywords : rare-earth intermetallics * magnetic properties * single crystal growth Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.327, year: 2010

  10. Heating efficiency in magnetic nanoparticle hyperthermia

    International Nuclear Information System (INIS)

    Deatsch, Alison E.; Evans, Benjamin A.

    2014-01-01

    Magnetic nanoparticles for hyperthermic treatment of cancers have gained significant attention in recent years. In magnetic hyperthermia, three independent mechanisms result in thermal energy upon stimulation: Néel relaxation, Brownian relaxation, and hysteresis loss. The relative contribution of each is strongly dependent on size, shape, crystalline anisotropy, and degree of aggregation or agglomeration of the nanoparticles. We review the effects of each of these physical mechanisms in light of recent experimental studies and suggest routes for progress in the field. Particular attention is given to the influence of the collective behaviors of nanoparticles in suspension. A number of recent studies have probed the effect of nanoparticle concentration on heating efficiency and have reported superficially contradictory results. We contextualize these studies and show that they consistently indicate a decrease in magnetic relaxation time with increasing nanoparticle concentration, in both Brownian- and Néel-dominated regimes. This leads to a predictable effect on heating efficiency and alleviates a significant source of confusion within the field. - Highlights: • Magnetic nanoparticle hyperthermia. • Heating depends on individual properties and collective properties. • We review recent studies with respect to loss mechanisms. • Collective behavior is a key source of confusion in the field. • We contextualize recent studies to elucidate consistencies and alleviate confusion

  11. Liquid neon heat intercept for superconducting energy storage magnets

    International Nuclear Information System (INIS)

    Khalil, A.; McIntosh, G.E.

    1982-01-01

    Previous analyses of heat intercept solutions are extended to include both insulation and strut heat leaks. The impact of using storable, boiling cryogens for heat intercept fluids, specifically liquid neon and nitrogen, is also examined. The selection of fluid for the heat intercepts is described. Refrigeration power for 1000 and 5000 MWhr SMES units is shown with optimum refrigeration power for each quantity shown in tables. Nitrogen and Neon cooled intercept location for minimum total refrigeration power for a 5000 MWhr SMES are each shown, as well as the location of nitrogen and neon cooled intercepts for minimum total refrigeration power for 5000 MWhr SMES. Cost comparisons are itemized and neon cost and availability discussed. For a large energy storage magnet system, liquid neon is a more effective heat intercept fluid than liquid nitrogen. Reasons and application of the conclusion are amplified

  12. MEASUREMENT OF SPECIFIC HEAT CAPACITY OF SALTSTONE

    International Nuclear Information System (INIS)

    Harbour, J.; Williams, V.

    2008-01-01

    One of the goals of the Saltstone variability study is to identify (and quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone grout mixtures. The heat capacity of the Saltstone waste form is one of the important properties of Saltstone mixes that was last measured at SRNL in 1997. It is therefore important to develop a core competency for rapid and accurate analysis of the specific heat capacity of the Saltstone mixes in order to quantify the impact of compositional and operational variations on this property as part of the variability study. The heat capacity, coupled with the heat of hydration data obtained from isothermal calorimetry for a given Saltstone mix, can be used to predict the maximum temperature increase in the cells within the vaults of the Saltstone Disposal Facility (SDF). The temperature increase controls the processing rate and the pour schedule. The maximum temperature is also important to the performance properties of the Saltstone. For example, in mass pours of concrete or grout of which Saltstone is an example, the maximum temperature increase and the maximum temperature difference (between the surface and the hottest location) are controlled to ensure durability of the product and prevent or limit the cracking caused by the thermal gradients produced during curing. This report details the development and implementation of a method for the measurement of the heat capacities of Saltstone mixes as well as the heat capacities of the cementitious materials of the premix and the simulated salt solutions used to batch the mixes. The developed method utilizes the TAM Air isothermal calorimeter and takes advantage of the sophisticated heat flow measurement capabilities of the instrument. Standards and reference materials were identified and used to validate the procedure and ensure accuracy of testing. Heat capacities of Saltstone mixes were

  13. MEASUREMENT OF SPECIFIC HEAT CAPACITY OF SALTSTONE

    Energy Technology Data Exchange (ETDEWEB)

    Harbour, J; Vickie Williams, V

    2008-09-29

    One of the goals of the Saltstone variability study is to identify (and quantify the impact of) the operational and compositional variables that control or influence the important processing and performance properties of Saltstone grout mixtures. The heat capacity of the Saltstone waste form is one of the important properties of Saltstone mixes that was last measured at SRNL in 1997. It is therefore important to develop a core competency for rapid and accurate analysis of the specific heat capacity of the Saltstone mixes in order to quantify the impact of compositional and operational variations on this property as part of the variability study. The heat capacity, coupled with the heat of hydration data obtained from isothermal calorimetry for a given Saltstone mix, can be used to predict the maximum temperature increase in the cells within the vaults of the Saltstone Disposal Facility (SDF). The temperature increase controls the processing rate and the pour schedule. The maximum temperature is also important to the performance properties of the Saltstone. For example, in mass pours of concrete or grout of which Saltstone is an example, the maximum temperature increase and the maximum temperature difference (between the surface and the hottest location) are controlled to ensure durability of the product and prevent or limit the cracking caused by the thermal gradients produced during curing. This report details the development and implementation of a method for the measurement of the heat capacities of Saltstone mixes as well as the heat capacities of the cementitious materials of the premix and the simulated salt solutions used to batch the mixes. The developed method utilizes the TAM Air isothermal calorimeter and takes advantage of the sophisticated heat flow measurement capabilities of the instrument. Standards and reference materials were identified and used to validate the procedure and ensure accuracy of testing. Heat capacities of Saltstone mixes were

  14. Effective Induction Heating around Strongly Magnetized Stars

    Science.gov (United States)

    Kislyakova, K. G.; Fossati, L.; Johnstone, C. P.; Noack, L.; Lüftinger, T.; Zaitsev, V. V.; Lammer, H.

    2018-05-01

    Planets that are embedded in the changing magnetic fields of their host stars can experience significant induction heating in their interiors caused by the planet’s orbital motion. For induction heating to be substantial, the planetary orbit has to be inclined with respect to the stellar rotation and dipole axes. Using WX UMa, for which the rotation and magnetic axes are aligned, as an example, we show that for close-in planets on inclined orbits, induction heating can be stronger than the tidal heating occurring inside Jupiter’s satellite Io; namely, it can generate a surface heat flux exceeding 2 W m‑2. An internal heating source of such magnitude can lead to extreme volcanic activity on the planet’s surface, possibly also to internal local magma oceans, and to the formation of a plasma torus around the star aligned with the planetary orbit. A strongly volcanically active planet would eject into space mostly SO2, which would then dissociate into oxygen and sulphur atoms. Young planets would also eject CO2. Oxygen would therefore be the major component of the torus. If the O I column density of the torus exceeds ≈1012 cm‑2, the torus could be revealed by detecting absorption signatures at the position of the strong far-ultraviolet O I triplet at about 1304 Å. We estimate that this condition is satisfied if the O I atoms in the torus escape the system at a velocity smaller than 1–10 km s‑1. These estimates are valid also for a tidally heated planet.

  15. Specific heat, polarization and heat conduction in microwave heating systems: A nonequilibrium thermodynamic point of view

    International Nuclear Information System (INIS)

    Bergese, Paolo

    2006-01-01

    A microwave (MW) field can induce in a dielectric material an oscillatory polarization. By this mechanism part of the energy carried by the waves is converted into chaotic agitation, and the material heats up. MW heating is a nonequilibrium phenomenon, while conventional heating can generally be considered as quasi-static. Excess (or nonthermal) effects of MWs with respect to conventional heating lie in this difference. Macroscopically, MW heating can be described in the framework of linear nonequilibrium thermodynamics (NET). This approach indicates that in a dielectric material under MW heating the specific heat has a dynamic component linked to the variation of polarization with temperature, and that polarization and heat conduction are intertwined. In particular, linear NET provides a new phenomenological equation for heat conduction that is composed of the classic Fourier's law and an additional term due to polarization relaxation. This term quantitatively describes the excess effect of MWs on thermal conduction

  16. Magnetic induction heating of FeCr nanocrystalline alloys

    International Nuclear Information System (INIS)

    Gómez-Polo, C.; Larumbe, S.; Pérez-Landazábal, J.I.; Pastor, J.M.; Olivera, J.; Soto-Armañanzas, J.

    2012-01-01

    In this work the thermal effects of magnetic induction heating in (FeCr) 73.5 Si 13.5 Cu 1 B 9 Nb 3 amorphous and nanocrystalline wires were analyzed. A single piece of wire was immersed in a glass capillary filled with water and subjected to an ac magnetic field (frequency, 320 kHz). The initial temperature rise enabled the determination of the effective Specific Absorption Rate (SAR). Maximum SAR values are achieved for those samples displaying high magnetic susceptibility, where the eddy current losses dominate the induction heating behavior. Moreover, the amorphous sample with Curie temperature around room temperature displays characteristic features of self-regulated hyperthermia. - Highlights: ► Amorphous and nanocrystalline Fe based alloys with tailored Curie temperature of the amorphous phase. ► Induction heating effects under the action of a ac magnetic field. ► Self-regulated characteristics based on the control of the Curie temperature. ► Dominant role of the eddy-current losses in the self-heating phenomena.

  17. Specific heat of praseodymium and neodymium

    International Nuclear Information System (INIS)

    Narayana Murthy, J.V.S.S.; Ramji Rao, R.

    1983-01-01

    The elements of the dynamical matrix of an ideal deep lattice, with nearest neighbour central interactions, have been obtained in a homogeneously strained state. The dispersion relations along the [0001] direction, on this model, have been presented for Pr and Nd. The frequency distribution function g(ω) is obtained and the lattice specific heat is calculated for Pr and Nd and the temperature variation of the equivalent Debye temperature is presented. (author)

  18. Magnetic fields in laser heated plasmas

    International Nuclear Information System (INIS)

    Amiranoff, F.; Brackbill, J.; Colombant, D.; Grandjouan, N.

    1984-01-01

    With a fixed-ion code for the study of self-generated magentic fields in laser heated plasmas, the inhibition of thermal transport and the effect of the Nernst term are modeled for a KrF laser. For various values of the flux limiter, the response of a foil to a focused laser is calculated without a magnetic field and compared with the response calculated with a magnetic field. The results are: The Nernst term convects the magnetic field to densities above critical as found by Nishiguchi et al. (1984), but the field does not strongly inhibit transport into the foil. The field is also transported to sub-critical densities, where it inhibits thermal diffusion and enhance lateral transport by convection

  19. Synthesis of FeCo magnetic nanoalloys and investigation of heating properties for magnetic fluid hyperthermia

    Science.gov (United States)

    Çelik, Özer; Fırat, Tezer

    2018-06-01

    In this study, size controlled FeCo colloidal magnetic nanoalloys in the range of 11.5-37.2 nm were synthesized by surfactant assistant ball milling method. Magnetic separation technique was performed subsequent to synthesis process so as to obtain magnetic nanoalloy fluid with narrow size distribution. Particle distribution was determined by transmission electron microscope (TEM) while X-ray diffraction (XRD) measurements verified FeCo alloy formation as BCC structure. Vibrating sample magnetometer (VSM) method was used to investigate magnetic properties of nanoalloys. Maximum saturation magnetization and maximum coercivity were obtained as 172 Am2/kg for nanoparticles with the mean size of 37.2 nm and 19.4 mT for nanoparticles with the mean size of 13.3 nm, respectively. The heating ability of FeCo magnetic nanoalloys was determined through calorimetrical measurements for magnetic fluid hyperthermia (MFH) applications. Heat generation mechanisms were investigated by using linear response theory and Stoner-Wohlfarth (S-W) model. Specific absorption rate (SAR) values were obtained in the range of 2-15 W/g for magnetic field frequency of 171 kHz and magnetic field strength in between 6 and 14 mT.

  20. Influence of chemical composition on the X-ray photoemission, thermopower, specific heat, and magnetic properties of CeNi{sub 2}(Si{sub 1-y}Ge{sub y}){sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Tolinski, T.; Synoradzki, K. [Polish Academy of Sciences, Institute of Molecular Physics, Poznan (Poland); Bajorek, A.; Chelkowska, G. [Silesian University, Institute of Physics, Katowice (Poland); Koterlyn, M. [K. Wielkiego University, Institute of Physics, Bydgoszcz (Poland); Ivan Franko National University of L' viv, Faculty of Electronics, L' viv (Ukraine); Koterlyn, G. [National Academy of Sciences of Ukraine and Ministry of Education and Science of Ukraine, Western Scientific Center, L' viv (Ukraine); Yasnitskii, R. [Ivan Franko National University of L' viv, Faculty of Electronics, L' viv (Ukraine)

    2017-06-15

    We report our studies of the intermediate compositions between CeNi{sub 2}Si{sub 2} and CeNi{sub 2}Ge{sub 2}, i.e., the alloys CeNi{sub 2}(Si{sub 1-y}Ge{sub y}){sub 2} by means of the thermopower, electrical resistivity, specific heat, magnetic susceptibility, and X-ray photoemission measurements. CeNi{sub 2}Si{sub 2} is a fluctuating valence system and CeNi{sub 2}Ge{sub 2} is known to show the heavy fermion behaviour. The change of the temperature dependence of the resistivity towards the typical metallic behaviour occurs below y ∝ 0.25. The transition between CeNi{sub 2}Si{sub 2} and CeNi{sub 2}Ge{sub 2} is discussed in the frames of competition between the crystal electric field and Kondo interactions. It is found that valence stabilisation occurs for Ge content y > 0.25. The hybridization energy Δ determined from the XPS Ce 3d spectrum reflects well the behaviour of the parameter E{sub ex} obtained from the analysis of the magnetic susceptibility by the interconfiguration fluctuation model. It has been also shown that thermopower data can be successfully described employing the single ion model for 0.6 < y < 1.0 and two-band model including the crystal electric field splitting for y ≤ 0.25. (orig.)

  1. Heat pipe cooling of power processing magnetics

    Science.gov (United States)

    Hansen, I. G.; Chester, M.

    1979-01-01

    The constant demand for increased power and reduced mass has raised the internal temperature of conventionally cooled power magnetics toward the upper limit of acceptability. The conflicting demands of electrical isolation, mechanical integrity, and thermal conductivity preclude significant further advancements using conventional approaches. However, the size and mass of multikilowatt power processing systems may be further reduced by the incorporation of heat pipe cooling directly into the power magnetics. Additionally, by maintaining lower more constant temperatures, the life and reliability of the magnetic devices will be improved. A heat pipe cooled transformer and input filter have been developed for the 2.4 kW beam supply of a 30-cm ion thruster system. This development yielded a mass reduction of 40% (1.76 kg) and lower mean winding temperature (20 C lower). While these improvements are significant, preliminary designs predict even greater benefits to be realized at higher power. This paper presents the design details along with the results of thermal vacuum operation and the component performance in a 3 kW breadboard power processor.

  2. Magnetization process of heat assisted magnetic recording by micro-magnetic simulation

    International Nuclear Information System (INIS)

    Shiiki, Kazuo; Motojima, Hisanori

    2010-01-01

    Magnetization reversal in a uniform magnetic field and one bit recording process by a thin film head in the heat assisted magnetic recording system of TbFeCo medium are studied by using the micro-magnetic simulation and the heat equation. The Landau-Lifsitz-Gilbert equation is solved for magnetic parameters at temperatures as the time goes by. It is found that magnetization proceeds as a progressive wave, although this behaviour may not limit the recording speed. The recording bit is expanded by the thermal fluctuation. The expansion can be suppressed as the medium thickness increases, because the thermal fluctuation is small in the thick medium. So the control of the medium thickness is important very much to achieve a high-density heat-assisted recording.

  3. Induction-heating MOCVD reactor with significantly improved heating efficiency and reduced harmful magnetic coupling

    KAUST Repository

    Li, Kuang-Hui; Alotaibi, Hamad S.; Sun, Haiding; Lin, Ronghui; Guo, Wenzhe; Torres-Castanedo, Carlos G.; Liu, Kaikai; Galan, Sergio V.; Li, Xiaohang

    2018-01-01

    In a conventional induction-heating III-nitride metalorganic chemical vapor deposition (MOCVD) reactor, the induction coil is outside the chamber. Therefore, the magnetic field does not couple with the susceptor well, leading to compromised heating efficiency and harmful coupling with the gas inlet and thus possible overheating. Hence, the gas inlet has to be at a minimum distance away from the susceptor. Because of the elongated flow path, premature reactions can be more severe, particularly between Al- and B-containing precursors and NH3. Here, we propose a structure that can significantly improve the heating efficiency and allow the gas inlet to be closer to the susceptor. Specifically, the induction coil is designed to surround the vertical cylinder of a T-shaped susceptor comprising the cylinder and a top horizontal plate holding the wafer substrate within the reactor. Therefore, the cylinder coupled most magnetic field to serve as the thermal source for the plate. Furthermore, the plate can block and thus significantly reduce the uncoupled magnetic field above the susceptor, thereby allowing the gas inlet to be closer. The results show approximately 140% and 2.6 times increase in the heating and susceptor coupling efficiencies, respectively, as well as a 90% reduction in the harmful magnetic flux on the gas inlet.

  4. Induction-heating MOCVD reactor with significantly improved heating efficiency and reduced harmful magnetic coupling

    KAUST Repository

    Li, Kuang-Hui

    2018-02-23

    In a conventional induction-heating III-nitride metalorganic chemical vapor deposition (MOCVD) reactor, the induction coil is outside the chamber. Therefore, the magnetic field does not couple with the susceptor well, leading to compromised heating efficiency and harmful coupling with the gas inlet and thus possible overheating. Hence, the gas inlet has to be at a minimum distance away from the susceptor. Because of the elongated flow path, premature reactions can be more severe, particularly between Al- and B-containing precursors and NH3. Here, we propose a structure that can significantly improve the heating efficiency and allow the gas inlet to be closer to the susceptor. Specifically, the induction coil is designed to surround the vertical cylinder of a T-shaped susceptor comprising the cylinder and a top horizontal plate holding the wafer substrate within the reactor. Therefore, the cylinder coupled most magnetic field to serve as the thermal source for the plate. Furthermore, the plate can block and thus significantly reduce the uncoupled magnetic field above the susceptor, thereby allowing the gas inlet to be closer. The results show approximately 140% and 2.6 times increase in the heating and susceptor coupling efficiencies, respectively, as well as a 90% reduction in the harmful magnetic flux on the gas inlet.

  5. Theoretical predictions for spatially-focused heating of magnetic nanoparticles guided by magnetic particle imaging field gradients

    Energy Technology Data Exchange (ETDEWEB)

    Dhavalikar, Rohan [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); Rinaldi, Carlos, E-mail: carlos.rinaldi@bme.ufl.edu [Department of Chemical Engineering, University of Florida, 1030 Center Drive, Gainesville, FL 32611 (United States); J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, 1275 Center Drive, Gainesville, FL 32611 (United States)

    2016-12-01

    Magnetic nanoparticles in alternating magnetic fields (AMFs) transfer some of the field's energy to their surroundings in the form of heat, a property that has attracted significant attention for use in cancer treatment through hyperthermia and in developing magnetic drug carriers that can be actuated to release their cargo externally using magnetic fields. To date, most work in this field has focused on the use of AMFs that actuate heat release by nanoparticles over large regions, without the ability to select specific nanoparticle-loaded regions for heating while leaving other nanoparticle-loaded regions unaffected. In parallel, magnetic particle imaging (MPI) has emerged as a promising approach to image the distribution of magnetic nanoparticle tracers in vivo, with sub-millimeter spatial resolution. The underlying principle in MPI is the application of a selection magnetic field gradient, which defines a small region of low bias field, superimposed with an AMF (of lower frequency and amplitude than those normally used to actuate heating by the nanoparticles) to obtain a signal which is proportional to the concentration of particles in the region of low bias field. Here we extend previous models for estimating the energy dissipation rates of magnetic nanoparticles in uniform AMFs to provide theoretical predictions of how the selection magnetic field gradient used in MPI can be used to selectively actuate heating by magnetic nanoparticles in the low bias field region of the selection magnetic field gradient. Theoretical predictions are given for the spatial decay in energy dissipation rate under magnetic field gradients representative of those that can be achieved with current MPI technology. These results underscore the potential of combining MPI and higher amplitude/frequency actuation AMFs to achieve selective magnetic fluid hyperthermia (MFH) guided by MPI. - Highlights: • SAR predictions based on a field-dependent magnetization relaxation model.

  6. Heating ability and biocompatibility study of silica-coated magnetic ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 38; Issue 6. Heating ability and biocompatibility study of silica-coated magnetic nanoparticles as heating mediators for magnetic hyperthermia and magnetically triggered drug delivery systems. Meysam Soleymani Mohammad Edrissi. Volume 38 Issue 6 October 2015 ...

  7. Electronic specific heat of transition metal carbides

    International Nuclear Information System (INIS)

    Conte, R.

    1964-07-01

    The experimental results that make it possible to define the band structure of transition metal carbides having an NaCI structure are still very few. We have measured the electronic specific heat of some of these carbides of varying electronic concentration (TiC, either stoichiometric or non-stoichiometric, TaC and mixed (Ti, Ta) - C). We give the main characteristics (metallography, resistivity, X-rays) of our samples and we describe the low temperature specific heat apparatus which has been built. In one of these we use helium as the exchange gas. The other is set up with a mechanical contact. The two use a germanium probe for thermometer. The measurement of the temperature using this probe is described, as well as the various measurement devices. The results are presented in the form of a rigid band model and show that the density of the states at the Fermi level has a minimum in the neighbourhood of the group IV carbides. (author) [fr

  8. Heat generation and cooling of SSC magnets at high ramp rates

    International Nuclear Information System (INIS)

    Snitchler, G.; Capone, D.; Kovachev, V.; Schermer, R.

    1992-01-01

    This presentation will address a summary of AC loss calculations (SSCL), experimental results on cable samples (Westinghouse STC), short model magnets test results (FNAL, KEK-Japan), and recent full length magnets test data on AC losses and quench current ramp rate sensitivity (FNAL, BNL). Possible sources of the observed enhanced heat generation and quench sensitivity for some magnets will be discussed. A model for cooling conditions of magnet coils considering heat generation distribution and specific anisotropy of the heat transfer will be presented. The crossover contact resistance in cables and curing procedure influence on resistivity, currently under study, will be briefly discussed. (author)

  9. Heat transfer control in a plane magnetic fluid layer with a free surface

    International Nuclear Information System (INIS)

    Bashtovoi, V.G.; Pogirnitskaya, S.G.; Reks, A.G.

    1993-01-01

    The heat transfer mechanisms that are specific to a magnetic liquid have been already investigated extensively. The high sensitivity of the free magnetic liquid surface to the external magnetic field introduces a new feature into the heat transfer process. In the present work, the authors have investigated the possibility of controlling the heat transfer through the phenomenon of magnetic liquid surface instability in a uniform magnetic field. The conditions for heat transfer through a chamber, partially filled with a magnetic liquid, are governed by the characteristics of the free liquid surface and by its stability and development in the supercritical magnetic fields. The authors consider a model two-dimensional problem of heat transfer through a two-layer medium consisting of horizontally situated immiscible layers of magnetic and nonmagnetic liquids with given thermal conductivities. In the absence of an external magnetic field, the interface of the liquids represents a plane surface. In fields which exceed the critical magnitude, the interface is deformed along the wave. As the field intensity is increased, the amplitude of interface distortion becomes larger. The two-dimensional shape of the free magnetic liquid surface may be realized experimentally using two plane layers of magnetic and nonmagnetic liquids in a uniform magnetic field tangent to the interface of the component layers. 7 refs., 9 figs

  10. Heat leak testing of a superconducting RHIC dipole magnet at Brookhaven National Laboratory

    International Nuclear Information System (INIS)

    DeLalio, J.T.; Brown, D.P.; Sondericker, J.H.

    1993-01-01

    Brookhaven National Laboratory is currently performing heat load tests on a superconducting dipole magnet. The magnet is a prototype of the 360, 8 cm bore, arc dipole magnets that will be used in the Relativistic Heavy Ion Collider (RMC). An accurate measurement of the heat load is needed to eliminate cumulative errors when determining the REUC cryogenic system load requirements. The test setup consists of a dipole positioned between two quadrupoles in a common vacuum tank and heat shield. Piping and instrumentation are arranged to facilitate measurement of the heat load on the primary 4.6 K magnet load and the secondary 55 K heat shield load. Initial results suggest that the primary heat load is well below design allowances. The secondary load was found to be higher than estimated, but remained close to the budgeted amount. Overall, the dipole performed to specifications

  11. The analysis of the specific heat of RFe2Si2 compounds

    Czech Academy of Sciences Publication Activity Database

    Svoboda, P.; Vejpravová, J.; Honda, F.; Šantavá, E.; Schneeweiss, Oldřich; Komatsubara, T.

    2003-01-01

    Roč. 328, 1-2 (2003), s. 139-141 ISSN 0921-4526 R&D Projects: GA ČR GA106/02/0943 Institutional research plan: CEZ:AV0Z2041904 Keywords : specific heat * magnetic properties * intermetallics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.908, year: 2003

  12. Low temperature anomaly of light stimulated magnetization and heat capacity of the 1D diluted magnetic semiconductors

    Science.gov (United States)

    Geffe, Chernet Amente

    2018-03-01

    This article reports magnetization and specific heat capacity anomalies in one dimensional diluted magnetic semiconductors observed at very low temperatures. Based on quantum field theory double time temperature dependent Green function technique is employed to evaluate magnon dispersion and the time correlation function. It is understood that magnon-photon coupling and magnetic impurity concentration controls both, such that near absolute temperature magnetization is nearly zero and abruptly increase to saturation level with decreasing magnon-photon coupling strength. We also found out dropping of magnetic specific heat capacity as a result of increase in magnetic impurity concentration x, perhaps because of inter-band disorder that would suppress the enhancement of density of spin waves.

  13. Low temperature anomaly of light stimulated magnetization and heat capacity of the 1D diluted magnetic semiconductors

    Directory of Open Access Journals (Sweden)

    Chernet Amente Geffe

    2018-03-01

    Full Text Available This article reports magnetization and specific heat capacity anomalies in one dimensional diluted magnetic semiconductors observed at very low temperatures. Based on quantum field theory double time temperature dependent Green function technique is employed to evaluate magnon dispersion and the time correlation function. It is understood that magnon-photon coupling and magnetic impurity concentration controls both, such that near absolute temperature magnetization is nearly zero and abruptly increase to saturation level with decreasing magnon-photon coupling strength. We also found out dropping of magnetic specific heat capacity as a result of increase in magnetic impurity concentration x, perhaps because of inter-band disorder that would suppress the enhancement of density of spin waves.

  14. Electron heat transport in stochastic magnetic layer

    International Nuclear Information System (INIS)

    Becoulet, M.; Ghendrih, Ph.; Capes, H.; Grosman, A.

    1999-06-01

    Progress in the theoretical understanding of the local behaviour of the temperature field in ergodic layer was done in the framework of quasi-linear approach but this quasi-linear theory was not complete since the resonant modes coupling (due to stochasticity) was neglected. The stochastic properties of the magnetic field in the ergodic zone are now taken into account by a non-linear coupling of the temperature modes. The three-dimension heat transfer modelling in the ergodic-divertor configuration is performed by quasi-linear (ERGOT1) and non-linear (ERGOT2) numerical codes. The formalism and theoretical basis of both codes are presented. The most important effect that can be simulated with non-linear code is the averaged temperature profile flattening that occurs in the ergodic zone and the barrier creation that appears near the separatrix during divertor operation. (A.C.)

  15. Cappuccino and Specific Heat Versus Heat of Vaporization

    Science.gov (United States)

    Hidden, Frits; Boomsma, Jorn; Schins, Anton; van den Berg, Ed

    2012-02-01

    A cappuccino is prepared by adding about 50 mL frothing, foaming milk to a cup of espresso. Whole milk is best for foaming and the ideal milk temperature when adding it to the espresso is 65 °C. The espresso itself may be warmer than that. During the heating the milk should not burn, as that would spoil the taste. The best way is to heat the milk slowly while stirring to froth the milk and create foam. But modern cappuccino machines in restaurants do not have time for slow heating. Could we heat the milk by just adding hot water?

  16. An induction heating device using planar coil with high amplitude alternating magnetic fields for magnetic hyperthermia.

    Science.gov (United States)

    Wu, Zuhe; Zhuo, Zihang; Cai, Dongyang; Wu, Jian'an; Wang, Jie; Tang, Jintian

    2015-01-01

    Induction heating devices using the induction coil and magnetic nanoparticles (MNPs) are the way that the magnetic hyperthermia is heading. To facilitate the induction heating of in vivo magnetic nanoparticles in hyperthermia experiments on large animals. An induction heating device using a planar coil was designed with a magnetic field frequency of 328 kHz. The coil's magnetic field distribution and the device's induction heating performance on different concentrations of magnetic nanoparticles were measured. The alternating magnetic field produced in the axis position 165 mm away from the coil center is 40 Gs in amplitude; magnetic nanoparticles with a concentration higher than 80 mg. mL-1 can be heated up rapidly. Our results demonstrate that the device can be applied not only to in vitro and in small animal experiments of magnetic hyperthermia using MNPs, but also in large animal experiments.

  17. Experimental investigation of an active magnetic regenerative heat circulator applied to self-heat recuperation technology

    International Nuclear Information System (INIS)

    Kotani, Yui; Kansha, Yasuki; Ishizuka, Masanori; Tsutsumi, Atsushi

    2014-01-01

    An experimental investigation into an active magnetic regenerative (AMR) heat circulator based on self-heat recuperation technology, was conducted to evaluate its energy saving potential in heat circulation. In an AMR heat circulator, magnetocaloric effect is applied to recuperate the heat exergy of the process fluid. The recuperated heat can be reused to heat the feed process fluid and realize self-heat recuperation. In this paper, AMR heat circulator has newly been constructed to determine the amount of heat circulated when applied to self-heat recuperation and the energy consumption of the heat circulator. Gadolinium and water was used as the magnetocaloric working material and the process fluid, respectively. The heat circulated amount was determined by measuring the temperature of the process fluid and gadolinium. The net work input for heat circulation was obtained from the magnetizing and demagnetizing forces and the distance travelled by the magnetocaloric bed. The results were compared with the minimum work input needed for heat circulation derived from exergy loss during heat exchange. It was seen that the experimentally obtained value was close to the minimum work input needed for heat circulation. - Highlights: • AMR heat circulator has newly been constructed for experimental evaluation. • Heat circulation in the vicinity of Curie temperature was observed. • Energy consumption of an AMR heat circulator has been measured. • Energy saving for processes near Curie temperature of working material was seen

  18. Heat flux anomalies in Antarctica revealed from satellite magnetic data

    DEFF Research Database (Denmark)

    Maule, Cathrine Fox; Purucker, Michael E.; Olsen, Nils

    2005-01-01

    a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have...

  19. Development of Field Angle Resolved Specific Heat Measurement System for Unconventional Superconductors

    International Nuclear Information System (INIS)

    Kitamura, Yasuhiro; Matsubara, Takeshi; Machida, Yo; Izawa, Koichi; Onuki, Yoshichika; Salce, Bernard; Flouquet, Jacques

    2015-01-01

    We developed a measurement system for field angle resolved specific heat under multiple extreme conditions at low temperature down to 50 mK, in magnetic field up to 7 T, and under high pressure up to 10 GPa. We demonstrated the performance of our developed system by measuring field angle dependence of specific heat of pressure induced unconventional superconductor CeIrSi 3

  20. Magnetic properties of heat treated bacterial ferrihydrite nanoparticles

    International Nuclear Information System (INIS)

    Balaev, D.A.; Krasikov, A.A.; Dubrovskiy, A.A.; Popkov, S.I.; Stolyar, S.V.; Bayukov, O.A.; Iskhakov, R.S.; Ladygina, V.P.; Yaroslavtsev, R.N.

    2016-01-01

    The magnetic properties of ferrihydrite nanoparticles, which are products of vital functions of Klebsiella oxitoca bacteria, have been studied. The initial powder containing the nanoparticles in an organic shell was subjected to low-temperature (T=160 °C) heat treatment for up to 240 h. The bacterial ferrihydrite particles exhibit a superparamagnetic behavior. Their characteristic blocking temperature increases from 26 to 80 K with the heat treatment. Analysis of the magnetization curves with regard to the magnetic moment distribution function and antiferromagnetic contribution shows that the low-temperature heat treatment enhances the average magnetic moment of a particle; i.e., the nanoparticles coarsen, probably due to their partial agglomeration during heat treatment. It was established that the blocking temperature nonlinearly depends on the particle volume. Therefore, a model was proposed that takes into account both the bulk and surface magnetic anisotropy. Using this model, the bulk and surface magnetic anisotropy constants K V ≈1.7×10 5 erg/cm 3 and K S ≈0.055 erg/cm 2 have been determined. The effect of the surface magnetic anisotropy of ferrihydrite nanoparticles on the observed magnetic hysteresis loops is discussed. - Highlights: • Ferrihydrite nanoparticles of biogenic origin are obtained. • Magnetic characterization reveals superparamagnetic behavior. • The blocking temperature increases upon the low-temperature (T=160 °C) heat treatment. • The blocking temperature nonlinearly depends on the particle volume. • The bulk and surface magnetic anisotropy constants have been determined.

  1. Radiofrequency heating and magnetically induced displacement of dental magnetic attachments during 3.0 T MRI

    Science.gov (United States)

    Miyata, K; Hasegawa, M; Abe, Y; Tabuchi, T; Namiki, T; Ishigami, T

    2012-01-01

    Objective The aim of this study was to estimate the risk of injury from dental magnetic attachments due to their radiofrequency (RF) heating and magnetically induced displacement during 3.0 T MRI. Methods To examine the magnetic attachments, we adopted the American Society for Testing and Materials F2182-02a and F2052-06 standards in two MRI systems (Achieva 3.0 T Nova Dual; Philips, Tokyo, Japan, and Signa HDxt 3.0 T; GE Healthcare, Milwaukee, WI). The temperature change was measured in a cylindrical keeper (GIGAUSS D600; GC, Tokyo, Japan) with coping of the casting alloy and a keeper with a dental implant at the maximum specific absorption rate (SAR) for 20 min. To measure the magnetically induced displacement force, three sizes of keepers (GIGAUSS D400, D600 and D1000) were used in deflection angle tests conducted at the point of the maximum magnetic field strength. Results Temperature elevations of both coping and implant were higher in the Signa system than in the Achieva system. The highest temperature changes in the keeper with implant and keeper with coping were 0.6 °C and 0.8 °C in the Signa system, respectively. The temperature increase did not exceed 1.0 °C at any location. The deflection angle (α) was not measurable because it exceeded 90°. GIGAUSS D400 required an extra 3.0 g load to constrain the deflection angle to less than 45°; GIGAUSS D600 and D1000 required 5.0 and 9.0 g loads, respectively. Conclusions Dental magnetic attachments pose no risk due to RF heating and magnetically induced displacement at 3.0 T MRI. However, it is necessary to confirm that these keepers are securely attached to the prosthesis before imaging. PMID:22499128

  2. Magnetic susceptibility and specific heat of the one-dimensional conductor (H3O) sub (1,6) Pt (C2O4)2.nH2O at low temperatures

    International Nuclear Information System (INIS)

    Raede, H.S.

    1985-01-01

    It has been shown recently that some transition metal complexes exhibit one-dimensional metallic properties. It is reported, in this context, susceptibility and specific heat measurements of polycrystalline (H 3 O) 1 , 6 Pt(C 2 O 4 ) 2 .nH 2 O in the low temperature range. It is found that the susceptibility can be described by a non-uniform Curie law with a characteristic break in the slope. The specific heat reveals no linear temperature contribution, which could be explained by a transition into a Peierls distorted state. Until 13 0 K, the heat capacity follows a T 3 -law. Deviations at higher temperatures are possibly attributed to the anisotropy of the system [pt

  3. Magnetic nanofluid properties as the heat transfer enhancement agent

    Directory of Open Access Journals (Sweden)

    Roszko Aleksandra

    2016-01-01

    Full Text Available The main purpose of this paper was to investigate an influence of various parameters on the heat transfer processes with strong magnetic field utilization. Two positions of experimental enclosure in magnetic environment, two methods of preparation and three different concentrations of nanoparticles (0.0112, 0.056 and 0.112 vol.% were taken into account together with the magnetic field strength. Analysed nanofluids consisted of distilled water (diamagnetic and Cu/CuO particles (paramagnetic of 40–60 nm size. The nanofluids components had different magnetic properties what caused complex interaction of forces’ system. The heat transfer data and fluid flow structure demonstrated the influence of magnetic field on the convective phenomena. The most visible consequence of magnetic field application was the heat transfer enhancement and flow reorganization under applied conditions.

  4. Low-temperature specific heat of YMn sub 2 in the paramagnetic and antiferromagnetic phases

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, R.A.; Emerson, J.P.; Phillips, N.E. (Lawrence Berkeley Lab., CA (United States)); Ballou, R.; Lelievre-Berna, E. (Centre National de la Recherche Scientifique (CNRS), 38 - Grenoble (France). Lab. Louis Neel)

    1992-07-01

    The low-temperature specific heat of YMn{sub 2} has been measured at applied pressures of 0 to 7.7 kbar. A paramagnetic state is stabilized for moderate values of the applied pressure (of the order of 1.6 kbar). A large linear term in the specific heat, which decreases regularly with increasing pressure, is observed in this phase. It is ascribed to giant spin fluctuations associated with a magnetic-non magnetic instability and a strong geometrical spin frustration.

  5. The Heat Is on: An Inquiry-Based Investigation for Specific Heat

    Science.gov (United States)

    Herrington, Deborah G.

    2011-01-01

    A substantial number of upper-level science students and practicing physical science teachers demonstrate confusion about thermal equilibrium, heat transfer, heat capacity, and specific heat capacity. The traditional method of instruction, which involves learning the related definitions and equations, using equations to solve heat transfer…

  6. Heat analysis of the magnetic limiter plate for JT-60

    International Nuclear Information System (INIS)

    Nakamura, Hiroo; Ninomiya, Hiromasa; Shimizu, Masatsugu; Ohta, Mitsuru

    1977-03-01

    Heat analysis has been made of the magnetic limiter plate for JT-60. Test materials of the magnetic limiter plate are molybdenum, graphite, pyrolytic graphite and silicon carbide. It is assumed in calculation of the heat analysis that 10MW is deposited on the 2 cm wide surface of the magnetic limiter plate in about 10 sec. The magnetic limiter plate of pyrolytic graphite is a stack of pyrolytic graphite sheets, heat input is in the deposition plane to take advantage of the large heat conductivity along this plane. Pyrolytic graphite is the best in terms of temperature rise. The temperature of molybdenum and graphite rise up to 1800 0 C and 620 0 C, respectively, in an deposition of 10 MWx10sec. Silicon carbide is not suitable for the magnetic limiter plate. Because the plasma of the JT-60 discharges every 10 min, the average heat flux decreases to 17 w/cm 2 during the each interval. When the magnetic limiter plate has the above heat inflow, a maximum of above 1000 0 C occurs at the edge far from the joint to the thick ring of the vacuum vessel. To reduce heat load of the magnetic limiter plate, an alternating current (2 -- 5Hz) is superposed on the magnetic limiter coil current. The intersection of separatrix line and magnetic limiter plate then moves cyclically more than 10 cm. Concerning temperature distribution of the multi-groove magnetic limiter plate, its dimensions are determined by the limitation in vapor pressure to prevent the impurity inflow. (auth.)

  7. A two-stage heating scheme for heat assisted magnetic recording

    Science.gov (United States)

    Xiong, Shaomin; Kim, Jeongmin; Wang, Yuan; Zhang, Xiang; Bogy, David

    2014-05-01

    Heat Assisted Magnetic Recording (HAMR) has been proposed to extend the storage areal density beyond 1 Tb/in.2 for the next generation magnetic storage. A near field transducer (NFT) is widely used in HAMR systems to locally heat the magnetic disk during the writing process. However, much of the laser power is absorbed around the NFT, which causes overheating of the NFT and reduces its reliability. In this work, a two-stage heating scheme is proposed to reduce the thermal load by separating the NFT heating process into two individual heating stages from an optical waveguide and a NFT, respectively. As the first stage, the optical waveguide is placed in front of the NFT and delivers part of laser energy directly onto the disk surface to heat it up to a peak temperature somewhat lower than the Curie temperature of the magnetic material. Then, the NFT works as the second heating stage to heat a smaller area inside the waveguide heated area further to reach the Curie point. The energy applied to the NFT in the second heating stage is reduced compared with a typical single stage NFT heating system. With this reduced thermal load to the NFT by the two-stage heating scheme, the lifetime of the NFT can be extended orders longer under the cyclic load condition.

  8. Improving heat generation of magnetic nanoparticles by pre-orientation of particles in a static three tesla magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Mathias M., E-mail: Mathias.Beck@tum.de [Institute for Machine Tools and Industrial Management, Technical University of Munich, Boltzmannstr. 15, 85748 Garching (Germany); Lammel, Christian [Institute for Machine Tools and Industrial Management, Technical University of Munich, Boltzmannstr. 15, 85748 Garching (Germany); Gleich, Bernhard [Institute of Medical Engineering, Technical University of Munich, Boltzmannstr. 11, 85748 Garching (Germany)

    2017-04-01

    Inductive heating of electrically insulating materials like fiberglass reinforced thermoplastics (FRTP) without susceptors is not possible. However, due to their low thermal conductivity a volumetric heat generation method is advisable to reach short heating times to melt this material for reshaping. This can be done with magnetic nanoparticles as susceptors within the thermoplastic of the FRTP using Néel relaxation. During the heating process the particle's magnetic moment rotates with the field while the particle itself is fixed within the thermoplastic. Therefore the heat dissipation of each particle depends on its orientation within the field. To achieve the maximum heat generation of the particles we pre-oriented the particles within a plastic at the best angle to the applied AC field for induction. To do this, five mass percent nanoparticles were dispersed in an epoxy resin, which was then hardened at room temperature in a static three Tesla magnetic field. After its solidification the heating behavior of the sample was compared to a reference sample, which was hardened without a field. The oriented particles showed an increased heating rate when oriented parallel to the applied AC field. The absorption rate was 3.3 times as high as the undirected reference sample. When the alternating electromagnetic field was perpendicular to the oriented particles, the specific absorption rate was similar to that of the reference sample. We compare this result with theory and with calculations from literature, and conduct a numerical simulation. - Highlights: • Magnetic nanoparticles are aligned using a static three tesla magnetic field. • Inductive heating depends on the particles pre-orientation in a solid matrix. • Alignment increases the heat generation significantly.

  9. Natural convection heat transfer of fluid with temperature-dependent specific heat

    International Nuclear Information System (INIS)

    Tanaka, Amane; Kubo, Shinji; Akino, Norio

    1998-01-01

    The present study investigates natural convection from a heated vertical plate of fluid with temperature-dependent specific heat, which is introduced as a model of microencapsulated phase change material slurries (MCPCM slurries). The temperature dependence of specific heat is represented by Gauss function with three physical parameters (peak temperature, width of phase change temperature and latent heat). Boundary layer equations are solved numerically, and the velocity and temperature fields of the flow are obtained. The relation between the heat transfer coefficients and the physical parameters of specific heat is discussed. The results show that the velocities and temperatures are smaller, and the heat transfer coefficients are larger comparing with those of the fluid with constant specific heat. (author)

  10. Heat-source specification 500 watt(e) RTG

    International Nuclear Information System (INIS)

    1983-02-01

    This specification establishes the requirements for a 90 SrF 2 heat source and its fuel capsule for application in a 500 W(e) thermoelectric generator. The specification covers: fuel composition and quantity; the Hastelloy S fuel capsule material and fabrication; and the quality assurance requirements for the assembled heat source

  11. Feasibility analysis of reciprocating magnetic heat pumps

    Science.gov (United States)

    Larson, A. V.; Hartley, J. G.; Shelton, Sam V.; Smith, M. M.

    1989-01-01

    A reciprocating gadolinium core in a regeneration fluid column in the warm bore of a superconducting solenoidal magnet is considered for magnetic refrigeration in 3.517 MW (1000 ton) applications. A procedure is presented to minimize the amount of superconducting cable needed in the magnet design. Estimated system capital costs for an ideal magnetic refrigerator of this type become comparable to conventional chillers as the frequency of reciprocation approaches 10 Hertz. A 1-D finite difference analysis of a regenerator cycling at 0.027 Hertz is presented which exhibits some of the features seen in the experiments of G. V. Brown.

  12. Effect of heat treatment on structure and magnetic properties

    Indian Academy of Sciences (India)

    Fe46Co35Ni19/CNTs nanocomposites have been prepared by an easy two-step route including adsorption and heat treatment processes. We investigated the effect of heat treatment conditions on structure, morphology, nanoparticle sizes and magnetic properties of the Fe46Co35Ni19 alloy nanoparticles attached on the ...

  13. The low temperature specific heat of Lu-Cu-Y metallic glasses

    International Nuclear Information System (INIS)

    Mohammed, K.A.; Lanchester, P.C.

    1987-01-01

    The specific heat of a series of amorphous metallic alloys of the form Lu x Cu 0.37 Y 0.36 (x=0, 0.1, 0.3 and 0.4) has been measured between 2 and 50 K, primarily in order to be able to determine the non-magnetic contributions to the specific heat in magnetic Re-Cu-Y amorphous alloys. The data at low temperature fit the simple form C p =γT+βT 3 from which values of γ and θ D (0) have been determined. Consideration is given to the error that arises if Y is used rather than Lu or La in forming non-magnetic rare earth intermetallics for purposes of determining the non-magnetic contributions to the specific heat of magnetic samples. A simple procedure is described that allows a useful improvement in accuracy in estimating non-magnetic contributions below 20 K if Y is used. The method may also be useful if only a restricted range of compositions using Lu is possible. (orig.)

  14. Low temperature specific heat of Lu-Cu-Y metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mohammed, K.A.; Lanchester, P.C.

    1987-02-01

    The specific heat of a series of amorphous metallic alloys of the form Lu/sub x/Cu/sub 0.37/Y/sub 0.36/ (x=0, 0.1, 0.3 and 0.4) has been measured between 2 and 50 K, primarily in order to be able to determine the non-magnetic contributions to the specific heat in magnetic Re-Cu-Y amorphous alloys. The data at low temperature fit the simple form C/sub p/=..gamma..T+..beta..T/sup 3/ from which values of ..gamma.. and theta/sub D/(0) have been determined. Consideration is given to the error that arises if Y is used rather than Lu or La in forming non-magnetic rare earth intermetallics for purposes of determining the non-magnetic contributions to the specific heat of magnetic samples. A simple procedure is described that allows a useful improvement in accuracy in estimating non-magnetic contributions below 20 K if Y is used. The method may also be useful if only a restricted range of compositions using Lu is possible.

  15. Magnetic surface compression heating in the heliotron device

    International Nuclear Information System (INIS)

    Uo, K.; Motojima, O.

    1982-01-01

    The slow adiabatic compression of the plasma in the heliotron device is examined. It has a prominent characteristic that the plasma equilibrium always exists at each stage of the compression. The heating efficiency is calculated. We show the possible access to fusion. A large amount of the initial investment for the heating system (NBI or RF) is reduced by using the magnetic surface compression heating. (author)

  16. Prediction of Liquid Specific Heat Capacity of Food Lipids.

    Science.gov (United States)

    Zhu, Xiaoyi; Phinney, David M; Paluri, Sravanti; Heldman, Dennis R

    2018-04-01

    Specific heat capacity (c p ) is a temperature dependent physical property of foods. Lipid-being a macromolecular component of food-provides some fraction of the food's overall heat capacity. Fats/oils are complex chemicals that are generally defined by carbon length and degree of unsaturation. The objective of this investigation was to use advanced specific heat capacity measurement to determine the effect of fatty acid chemical structure on specific heat capacity of food lipids. In this investigation, the specific heat capacity of a series of triacylglycerols were measured to quantify the influence of fatty acid composition on specific heat capacity based on two parameters; the -average carbon number (C) and the average number of double bonds (U). A prediction model for specific heat capacity of food lipids as a function of C, U and temperature (T) has been developed. A multiple linear regression to the three-parameter model (R 2 = 0.87) provided a good fit to the experimental data. The prediction model was evaluated by comparison with previously published specific heat capacity values of vegetable oils. It was found that the model provided a 0.53% error, while three other models from the literature predicted c p values with 0.85% to 1.83% average relative deviation from experimental data. The outcomes from this research confirm that the thermophysical properties of fat present in foods are directly related to the physical chemical properties. The specific heat capacity of food products is widely used in process design. Improvements of current models to predict specific heat capacity of food products will assist in the development of efficient processes and in the control of food quality and safety. Furthermore, the understanding of how changes in chemical structure of macromolecular components of foods effect thermophysical properties may begin to allude to models that are not just empirical, but represent portions of the differences in chemistry. © 2018

  17. Detection of Second Order Melting Transitions in the HTSC's by Specific Heat Measurements?

    Science.gov (United States)

    Pierson, Stephen W.; Valls, Oriol T.

    1997-03-01

    The finite magnetic field phase transition in the high-temperature superconductors from the solid vortex lattice to the liquid has been under intense study recently. Detection of this melting is difficult but has been seen in magnetization and resistivity measurements. It has also been reported recently in specific heat measurements. In particular, in one case, evidence for a second order melting phase transition has been presented based on specific heat measurements.(M. Roulin, A. Junod, and E. Walker. Science 273), 1210 (1996). However, we present evidence that the feature in the specific heat data can be explained using a theory derived using the lowest-Landau-level approximation(Z. Tes)anović and A. V. Andreev, Phys. Rev. B 49, 4064 (1994) that does not invoke flux lattice melting arguments.

  18. High-field specific heats of A15 V3Si and Nb3Sn

    International Nuclear Information System (INIS)

    Stewart, G.R.; Brandt, B.L.

    1984-01-01

    In order to further understand the anomalous behavior of the specific heat of Nb 3 Sn in an 18-T magnetic field discovered by Stewart, Cort, and Webb [Phys. Rev. B 24, 3841 (1981)], we have performed specific-heat measurements on a different sample of Nb 3 Sn at lower fields both in the normal and mixed states, as well as measurement to 19 T on both transforming and nontransforming V 3 Si. The high-field data for V 3 Si indicate that this material behaves quite normally, and that γ/sup trans/ 3 Sn, however, remains anomalous, with both the same ''kink'' in the normal-state field data as observed by Stewart, Cort, and Webb (although at a slightly higher temperature) and unusual mixed-state behavior. The mixed-state specific heat of the V 3 Si samples is as expected, based on earlier work on the mixed-state specific heat of V and Nb

  19. Specific heat of the Ising linear chain in a Random field

    International Nuclear Information System (INIS)

    Silva, P.R.; Sa Barreto, F.C. de

    1984-01-01

    Starting from correlation identities for the Ising model the effect of a random field on the one dimension version of the model is studied. Explicit results for the magnetization, the two-particle correlation function and the specific heat are obtained for an uncorrelated distribution of the random fields. (Author) [pt

  20. A comparison of the heating effect of magnetic fluid between the alternating and rotating magnetic field

    International Nuclear Information System (INIS)

    Beković, Miloš; Trlep, Mladen; Jesenik, Marko; Hamler, Anton

    2014-01-01

    Magnetic fluids are distinct magnetic materials that have recently been the subject of extensive research precisely because of their unique properties. One of them is the heating effect when exposed to alternating magnetic fields, wherein the objective is to use this property in medicine as an alternative method for the treatment of tumors in the body. In this paper, we focus on two methods of magnetizing magnetic fluids, firstly using the alternating magnetic field (AMF), and secondly with the rotational magnetic field (RMF). The effects of the first are scientifically well-established, whilst the impact of RMF has not as yet been investigated as presented in this article. So far the effects of RMF have only been studied at low frequencies and high amplitudes, or vice versa. This article presents the results of heating at high frequencies and high magnetic field amplitudes, and the results compared with AMF. This paper presents the construction and implementation of a measuring system which is suitable both types of magnetic field. - Highlights: • Development of a new measurement system for the characterization of magnetic fluids. • System enables pulsed magnetic field, or a rotary magnetic field. • Analysis of the conditions to create a rotational magnetic field by means of a double power supply. • Good agreement between the analytical and numerical calculation of magnetic field and measurements. • Increase of the heating power when sample is exposed to rotating field compared to pulsating field

  1. Peltier heat of a small polaron in a magnetic semiconductor

    International Nuclear Information System (INIS)

    Liu, N.H.; Emin, D.

    1985-01-01

    For the first time the heat transported with a small polaron in both antiferromagnetic and ferromagnetic semiconductors is calculated. This heat, the Peltier heat, π, is obtained from the change of the entropy of the total system upon introduction of a charge carrier. We explicitly consider both the intrasite and intersite exchange interactions between a small polaron and the interacting spins of a spin-1/2 magnet. There are two competing magnetic contributions to the Peltier heat. First, adding the carrier increases the spin entropy of the system. This provides a positive contribution to π. Second, the exchange between the carrier and the sites about it enhances the exchange binding between these sites. This reduces the energetically allowable spin configurations and provides a negative contribution to π. At extremely high temperatures when kT exceeds the intrasite exchange energy, the first effect dominates. Then π is simply augmented by kT ln 2. However, well below the magnetic transition temperature the second effect dominates. In the experimentally accessible range between these limits both effects are comparable and sizable. The net magnetic contribution to the Peltier heat rises with temperature. Thus, a carrier's interactions with its magnetic environment produces a significant and distinctive contribution to its Peltier heat

  2. Peltier heat of a small polaron in a magnetic semiconductor

    International Nuclear Information System (INIS)

    Liu, N.L.H.; Emin, D.

    1984-01-01

    The heat transported with a small polaron in both antiferromagnetic and ferromagnetic semiconductors is calculated. This heat, the Peltier heat, π, is obtained from the change of the entropy of the total system upon introduction of a charge carrier. We explicitly consider both the intrasite and intersite exchange interactions between a small polaron and the interacting spins of a spin-1/2 magnet. There are two competing magnetic contributions to the Peltier heat. First, adding the carrier increases the spin entropy of the system. This provides a positive contribution to π. Second, the exchange between the carrier and the sites about it enhances the exchange binding between these sites. This reduces the energetically allowable spin configurations and provides a negative contribution to π. At extremely high temperature when kT exceeds the intrasite exchange energy, the first effect dominates. Then π is simply augmented by kTln2. However, well below the magnetic transition temperature the second effect dominates. In the experimentally accessible range between these limits both effects are comparable and sizable. The net magnetic contribution to the Peltier heat rises with temperature. Thus, a carrier's interactions with its magnetic environment produces a significant and distinctive contribution to its Peltier heat

  3. Magnetically Modulated Heat Transport in a Global Simulation of Solar Magneto-convection

    Energy Technology Data Exchange (ETDEWEB)

    Cossette, Jean-Francois [Laboratory for Atmospheric and Space Physics, Campus Box 600, University of Colorado, Boulder, CO 80303 (United States); Charbonneau, Paul [Département de Physique, Université de Montréal, C.P. 6128, Succ. Centre-Ville, Montréal, QC H3C 3J7 (Canada); Smolarkiewicz, Piotr K. [European Centre for Medium-Range Weather Forecasts, Reading, RG2 9AX (United Kingdom); Rast, Mark P., E-mail: Jean-Francois.Cossette@lasp.colorado.edu, E-mail: paulchar@astro.umontreal.ca, E-mail: smolar@ecmwf.int, E-mail: Mark.Rast@lasp.colorado.edu [Department of Astrophysical and Planetary Sciences, Laboratory for Atmospheric and Space Physics, Campus Box 391, University of Colorado, Boulder, CO 80303 (United States)

    2017-05-20

    We present results from a global MHD simulation of solar convection in which the heat transported by convective flows varies in-phase with the total magnetic energy. The purely random initial magnetic field specified in this experiment develops into a well-organized large-scale antisymmetric component undergoing hemispherically synchronized polarity reversals on a 40 year period. A key feature of the simulation is the use of a Newtonian cooling term in the entropy equation to maintain a convectively unstable stratification and drive convection, as opposed to the specification of heating and cooling terms at the bottom and top boundaries. When taken together, the solar-like magnetic cycle and the convective heat flux signature suggest that a cyclic modulation of the large-scale heat-carrying convective flows could be operating inside the real Sun. We carry out an analysis of the entropy and momentum equations to uncover the physical mechanism responsible for the enhanced heat transport. The analysis suggests that the modulation is caused by a magnetic tension imbalance inside upflows and downflows, which perturbs their respective contributions to heat transport in such a way as to enhance the total convective heat flux at cycle maximum. Potential consequences of the heat transport modulation for solar irradiance variability are briefly discussed.

  4. The Specific Heat of Matter at Low Temperatures

    CERN Document Server

    Tari, A

    2003-01-01

    Recent discoveries of new materials and improvements in calorimetric techniques have given new impetus to the subject of specific heat. Nevertheless, there is a serious lack of literature on the subject. This invaluable book, which goes some way towards remedying that, is concerned mainly with the specific heat of matter at ordinary temperatures. It discusses the principles that underlie the theory of specific heat and considers a number of theoretical models in some detail. The subject matter ranges from traditional materials to those recently discovered - heavy fermion compounds, high temper

  5. Experimental study of ion heating and acceleration during magnetic reconnection

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, S.C.

    2000-01-28

    This dissertation reports an experimental study of ion heating and acceleration during magnetic reconnection, which is the annihilation and topological rearrangement of magnetic flux in a conductive plasma. Reconnection is invoked often to explain particle heating and acceleration in both laboratory and naturally occurring plasmas. However, a simultaneous account of reconnection and its associated energy conversion has been elusive due to the extreme inaccessibility of reconnection events, e.g. in the solar corona, the Earth's magnetosphere, or in fusion research plasmas. Experiments for this work were conducted on MRX (Magnetic Reconnection Experiment), which creates a plasma environment allowing the reconnection process to be isolated, reproduced, and diagnosed in detail. Key findings of this work are the identification of local ion heating during magnetic reconnection and the determination that non-classical effects must provide the heating mechanism. Measured ion flows are sub-Alfvenic and can provide only slight viscous heating, and classical ion-electron interactions can be neglected due to the very long energy equipartition time. The plasma resistivity in the reconnection layer is seen to be enhanced over the classical value, and the ion heating is observed to scale with the enhancement factor, suggesting a relationship between the magnetic energy dissipation mechanism and the ion heating mechanism. The observation of non-classical ion heating during reconnection has significant implications for understanding the role played by non-classical dissipation mechanisms in generating fast reconnection. The findings are relevant for many areas of space and laboratory plasma research, a prime example being the currently unsolved problem of solar coronal heating. In the process of performing this work, local measurements of ion temperature and flows in a well-characterized reconnection layer were obtained for the first time in either laboratory or observational

  6. Experimental study of ion heating and acceleration during magnetic reconnection

    International Nuclear Information System (INIS)

    Hsu, S.C.

    2000-01-01

    This dissertation reports an experimental study of ion heating and acceleration during magnetic reconnection, which is the annihilation and topological rearrangement of magnetic flux in a conductive plasma. Reconnection is invoked often to explain particle heating and acceleration in both laboratory and naturally occurring plasmas. However, a simultaneous account of reconnection and its associated energy conversion has been elusive due to the extreme inaccessibility of reconnection events, e.g. in the solar corona, the Earth's magnetosphere, or in fusion research plasmas. Experiments for this work were conducted on MRX (Magnetic Reconnection Experiment), which creates a plasma environment allowing the reconnection process to be isolated, reproduced, and diagnosed in detail. Key findings of this work are the identification of local ion heating during magnetic reconnection and the determination that non-classical effects must provide the heating mechanism. Measured ion flows are sub-Alfvenic and can provide only slight viscous heating, and classical ion-electron interactions can be neglected due to the very long energy equipartition time. The plasma resistivity in the reconnection layer is seen to be enhanced over the classical value, and the ion heating is observed to scale with the enhancement factor, suggesting a relationship between the magnetic energy dissipation mechanism and the ion heating mechanism. The observation of non-classical ion heating during reconnection has significant implications for understanding the role played by non-classical dissipation mechanisms in generating fast reconnection. The findings are relevant for many areas of space and laboratory plasma research, a prime example being the currently unsolved problem of solar coronal heating. In the process of performing this work, local measurements of ion temperature and flows in a well-characterized reconnection layer were obtained for the first time in either laboratory or observational

  7. Lubricant depletion under various laser heating conditions in Heat Assisted Magnetic Recording (HAMR)

    Science.gov (United States)

    Xiong, Shaomin; Wu, Haoyu; Bogy, David

    2014-09-01

    Heat assisted magnetic recording (HAMR) is expected to increase the storage areal density to more than 1 Tb/in2 in hard disk drives (HDDs). In this technology, a laser is used to heat the magnetic media to the Curie point (~400-600 °C) during the writing process. The lubricant on the top of a magnetic disk could evaporate and be depleted under the laser heating. The change of the lubricant can lead to instability of the flying slider and failure of the head-disk interface (HDI). In this study, a HAMR test stage is developed to study the lubricant thermal behavior. Various heating conditions are controlled for the study of the lubricant thermal depletion. The effects of laser heating repetitions and power levels on the lubricant depletion are investigated experimentally. The lubricant reflow behavior is discussed as well.

  8. A novel heat engine for magnetizing superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Coombs, T A; Hong, Z; Zhu, X [Cambridge University Engineering Department, Trumpington Street, CB2 1PZ (United Kingdom); Krabbes, G [IFW Dresden, Helmholtzstrasse 20, 01069 Dresden (Germany)

    2008-03-01

    The potential of bulk melt-processed YBCO single domains to trap significant magnetic fields (Tomita and Murakami 2003 Nature 421 517-20; Fuchs et al 2000 Appl. Phys. Lett. 76 2107-9) at cryogenic temperatures makes them particularly attractive for a variety of engineering applications including superconducting magnets, magnetic bearings and motors (Coombs et al 1999 IEEE Trans. Appl. Supercond. 9 968-71; Coombs et al 2005 IEEE Trans. Appl. Supercond. 15 2312-5). It has already been shown that large fields can be obtained in single domain samples at 77 K. A range of possible applications exist in the design of high power density electric motors (Jiang et al 2006 Supercond. Sci. Technol. 19 1164-8). Before such devices can be created a major problem needs to be overcome. Even though all of these devices use a superconductor in the role of a permanent magnet and even though the superconductor can trap potentially huge magnetic fields (greater than 10 T) the problem is how to induce the magnetic fields. There are four possible known methods: (1) cooling in field; (2) zero field cooling, followed by slowly applied field; (3) pulse magnetization; (4) flux pumping. Any of these methods could be used to magnetize the superconductor and this may be done either in situ or ex situ. Ideally the superconductors are magnetized in situ. There are several reasons for this: first, if the superconductors should become demagnetized through (i) flux creep, (ii) repeatedly applied perpendicular fields (Vanderbemden et al 2007 Phys. Rev. B 75 (17)) or (iii) by loss of cooling then they may be re-magnetized without the need to disassemble the machine; secondly, there are difficulties with handling very strongly magnetized material at cryogenic temperatures when assembling the machine; thirdly, ex situ methods would require the machine to be assembled both cold and pre-magnetized and would offer significant design difficulties. Until room temperature superconductors can be prepared, the

  9. A novel heat engine for magnetizing superconductors

    International Nuclear Information System (INIS)

    Coombs, T A; Hong, Z; Zhu, X; Krabbes, G

    2008-01-01

    The potential of bulk melt-processed YBCO single domains to trap significant magnetic fields (Tomita and Murakami 2003 Nature 421 517-20; Fuchs et al 2000 Appl. Phys. Lett. 76 2107-9) at cryogenic temperatures makes them particularly attractive for a variety of engineering applications including superconducting magnets, magnetic bearings and motors (Coombs et al 1999 IEEE Trans. Appl. Supercond. 9 968-71; Coombs et al 2005 IEEE Trans. Appl. Supercond. 15 2312-5). It has already been shown that large fields can be obtained in single domain samples at 77 K. A range of possible applications exist in the design of high power density electric motors (Jiang et al 2006 Supercond. Sci. Technol. 19 1164-8). Before such devices can be created a major problem needs to be overcome. Even though all of these devices use a superconductor in the role of a permanent magnet and even though the superconductor can trap potentially huge magnetic fields (greater than 10 T) the problem is how to induce the magnetic fields. There are four possible known methods: (1) cooling in field; (2) zero field cooling, followed by slowly applied field; (3) pulse magnetization; (4) flux pumping. Any of these methods could be used to magnetize the superconductor and this may be done either in situ or ex situ. Ideally the superconductors are magnetized in situ. There are several reasons for this: first, if the superconductors should become demagnetized through (i) flux creep, (ii) repeatedly applied perpendicular fields (Vanderbemden et al 2007 Phys. Rev. B 75 (17)) or (iii) by loss of cooling then they may be re-magnetized without the need to disassemble the machine; secondly, there are difficulties with handling very strongly magnetized material at cryogenic temperatures when assembling the machine; thirdly, ex situ methods would require the machine to be assembled both cold and pre-magnetized and would offer significant design difficulties. Until room temperature superconductors can be prepared, the

  10. On the specific heat in a limited medium

    International Nuclear Information System (INIS)

    Suzuki, A.T.

    1980-03-01

    The specific heat of solids is studied, following the usual approach in which the solid is considered as an elastic, isotropic and continuum system which bears normal modes of characteristic frequency. (L.C.) [pt

  11. Free Magnetic Energy and Coronal Heating

    Science.gov (United States)

    Winebarger, Amy; Moore, Ron; Falconer, David

    2012-01-01

    Previous work has shown that the coronal X-ray luminosity of an active region increases roughly in direct proportion to the total photospheric flux of the active region's magnetic field (Fisher et al. 1998). It is also observed, however, that the coronal luminosity of active regions of nearly the same flux content can differ by an order of magnitude. In this presentation, we analyze 10 active regions with roughly the same total magnetic flux. We first determine several coronal properties, such as X-ray luminosity (calculated using Hinode XRT), peak temperature (calculated using Hinode EIS), and total Fe XVIII emission (calculated using SDO AIA). We present the dependence of these properties on a proxy of the free magnetic energy of the active region

  12. Heat generation in agglomerated ferrite nanoparticles in an alternating magnetic field

    International Nuclear Information System (INIS)

    Lima, E Jr; De Biasi, E; Mansilla, M Vasquez; Saleta, M E; Granada, M; Troiani, H E; Zysler, R D; Effenberger, F B; Rossi, L M; Rechenberg, H R

    2013-01-01

    The role of agglomeration and magnetic interparticle interactions in heat generation of magnetic ferrofluids in an ac magnetic field is still unclear, with apparent discrepancy between the results presented in the literature. In this work, we measured the heat generating capability of agglomerated ferrite nanoparticles in a non-invasive ac magnetic field with f = 100 kHz and H 0 = 13 kA m -1 . The nanoparticles were morphologically and magnetically characterized, and the specific absorption rate (SAR) for our ac magnetic field presents a clear dependence on the diameter of the nanoparticles, with a maximum SAR = 48 W g -1 for 15 nm. Our agglomerated nanoparticles have large hydrodynamic diameters, thus the mechanical relaxation can be neglected as a heat generation mechanism. Therefore, we present a model that simulates the SAR dependence of the agglomerated samples on the diameter of the nanoparticles based on the hysteresis losses that is valid for the non-linear region (with H 0 comparable to the anisotropy field). Our model takes into account the magnetic interactions among the nanoparticles in the agglomerate. For comparison, we also measured the SAR of non-agglomerated nanoparticles in a similar diameter range, in which Néel and Brown relaxations dominate the heat generation.

  13. Performances of four magnetic heat-pump cycles

    International Nuclear Information System (INIS)

    Chen, F.C.; Murphy, R.W.; Mel, V.C.; Chen, G.L.

    1990-01-01

    Magnetic heat pumps have been successfully used for refrigeration applications at near absolute-zero-degree temperatures. In these applications, a temperature lift of a few degrees in a cryogenic environment is sufficient and can be easily achieved by a simple magnetic heat-pump cycle. To extend magnetic heat pumping to other temperature ranges and other types of applications in which the temperature lift is more than just a few degrees requires more involved cycle processes. This paper investigates the characteristics of a few better-known thermomagnetic heat-pump cycles (Carnot, Ericsson, Stirling, and regenerative) in extended ranges of temperature lift. The regenerative cycle is the most efficient one. For gadolinium operating between 0 and 7 T (Tesla) in a heat pump cycle with a heat-rejection temperature of 320 K, our analysis predicted a 42% loss in coefficient of performance at 260 K cooling temperature, and a 15% loss in capacity at 232 K cooling temperature for the constant-field cycle as compared with the ideal regenerative cycle. Such substantial penalties indicate that the potential irreversibilities from this one source (the additional heat transfer that would be needed for the constant-field vs. the ideal regenerative cycle) may adversely affect the viability of certain proposed MHP concepts if the relevant loss mechanisms are not adequately addressed

  14. Electronic specific heats in metal--hydrogen systems

    International Nuclear Information System (INIS)

    Flotow, H.E.

    1979-01-01

    The electronic specific heats of metals and metal--hydrogen systems can in many cases be evaluated from the measured specific heats at constant pressure, C/sub p/, in the temperature range 1 to 10 K. For the simplest case, C/sub p/ = γT + βT 3 , where γT represents the specific heat contribution associated with the conduction electrons, and βT 3 represents lattice specific heat contribution. The electronic specific heat coefficient, γ, is important because it is proportional to electron density of states at the Fermi surface. A short description of a low temperature calorimetric cryostat employing a 3 He/ 4 He dilution refrigeration is given. Various considerations and complications encountered in the evaluation of γ from specific heat data are discussed. Finally, the experimental values of γ for the V--Cr--H system and for the Lu--H system are summarized and the variations of γ as function of alloy composition are discussed

  15. Heat diffusion and magnetic field generation

    International Nuclear Information System (INIS)

    Holstein, P.A.

    1983-10-01

    In the report of CECAM workshop in 1982 some results of heat diffusion, when the spontaneous B-field is calculated, have been given. Separately, a similar code (magneto-calo-dynamic or MCD code) has been built and it was interesting to compare them. Comparisom has been made during the workshop of October 1983

  16. Role of Magnetic Carpet in Coronal Heating

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... One of the fundamental questions in solar physics is how the solar corona maintains its high temperature of several million Kelvin above photosphere with a temperature of 6000 K. Observations show that solar coronal heating problem is highly complex with many different facts. It is likely that different ...

  17. Conceptual design of an active magnetic regenerative heat circulator based on self-heat recuperation technology

    International Nuclear Information System (INIS)

    Kotani, Yui; Kansha, Yasuki; Tsutsumi, Atsushi

    2013-01-01

    A conceptual design of an active magnetic regenerative (AMR) heat circulator for self-heat recuperation to realize energy savings in thermal processes is proposed. The process fluid heat is recuperated by the magnetocaloric effect of ferromagnetic material through the AMR heat circulation cycle. In an AMR heat circulator, all the process fluid heat is circulated and no make-up heat is added to raise the process fluid to its set temperature. A one-dimensional mathematical model of the AMR heat circulator was constructed to understand its behavior and verify its energy-saving potential. From the constructed one-dimensional mathematical model, it is seen that AMR heat circulator has potential to drastically reduce the total energy consumption in a thermal process. The temperature–entropy diagram shows that in order to gain the maximum energy saving, optimization of the parameters such as the flow rate and geometry of the ferromagnetic working material beds is needed. - Highlights: • Self-heat recuperative active magnetic regenerative heat circulator is introduced. • One-dimensional model is constructed to verify its energy-saving potential. • Total energy consumption in thermal process is drastically reduced. • Further energy can be saved by reducing the overlapping of thermodynamic cycles

  18. Analysis of self-heating of thermally assisted spin-transfer torque magnetic random access memory

    Directory of Open Access Journals (Sweden)

    Austin Deschenes

    2016-11-01

    Full Text Available Thermal assistance has been shown to significantly reduce the required operation power for spin torque transfer magnetic random access memory (STT-MRAM. Proposed heating methods include modified material stack compositions that result in increased self-heating or external heat sources. In this work we analyze the self-heating process of a standard perpendicular magnetic anisotropy STT-MRAM device through numerical simulations in order to understand the relative contributions of Joule, thermoelectric Peltier and Thomson, and tunneling junction heating. A 2D rotationally symmetric numerical model is used to solve the coupled electro-thermal equations including thermoelectric effects and heat absorbed or released at the tunneling junction. We compare self-heating for different common passivation materials, positive and negative electrical current polarity, and different device thermal anchoring and boundaries resistance configurations. The variations considered are found to result in significant differences in maximum temperatures reached. Average increases of 3 K, 10 K, and 100 K for different passivation materials, positive and negative polarity, and different thermal anchoring configurations, respectively, are observed. The highest temperatures, up to 424 K, are obtained for silicon dioxide as the passivation material, positive polarity, and low thermal anchoring with thermal boundary resistance configurations. Interestingly it is also found that due to the tunneling heat, Peltier effect, device geometry, and numerous interfacial layers around the magnetic tunnel junction (MTJ, most of the heat is dissipated on the lower potential side of the magnetic junction. This asymmetry in heating, which has also been observed experimentally, is important as thermally assisted switching requires heating of the free layer specifically and this will be significantly different for the two polarity operations, set and reset.

  19. Micromagnetic modeling for heat-assisted magnetic recording

    International Nuclear Information System (INIS)

    Li Zhenghua; Wei Dan; Wei Fulin

    2008-01-01

    Heat-assisted magnetic recording (HAMR) is one of the candidate systems beyond the perpendicular recording technology. Here, a micromagnetic model and a heat transfer model are introduced to study the heating and cooling processes in the HAMR media; then, by integration of the SPT head and the laser heating source, the recording performance is simulated and investigated on a single track at an area density of 1 Tb/in 2 . In the HAMR system, the temperature in the medium under the laser wave guide is increased by heating, and decreased by air bearing and heat conduction when the write process really occurred. The target of this study is to find the proper design of the head-laser assembly for optimum recording. It is found that the proper distance between the laser wave guide and the head's main pole rear/front edge is only 41.4/1.4 nm for optimum recording performance

  20. Specifications, quality control, manufacturing, and testing of accelerator magnets

    CERN Document Server

    Einfeld, D

    2010-01-01

    The performance of the magnets plays an important role in the functioning of an accelerator. Most of the magnets are designed at the accelerator laboratory and built by industry. The link between the laboratory and the manufacturer is the contract containing the Technical Specifications of the magnets. For an overview of the contents of the Technical Specifications, the specifications for the magnets of ALBA (bending, quadrupole, and sextupole) are described in this paper. The basic rules of magnet design are reviewed in Appendix A.

  1. Specific heat of NiCl26NH3 between 0.3 and 4.2K

    International Nuclear Information System (INIS)

    Sano, W.

    1979-01-01

    A careful specific heat measurements of nickel hexammine cloride, at liquid helium temperatures, revealed two maxima of magnetic origin in agreement with one of the works available in the literature. An inequivalency of Ni ions, resulting from a structural change at high temperatures, is considered as the new explanation of the magnetic ordering. (Author) [pt

  2. The magnetic-nanofluid heat pipe with superior thermal properties through magnetic enhancement

    Science.gov (United States)

    2012-01-01

    This study developed a magnetic-nanofluid (MNF) heat pipe (MNFHP) with magnetically enhanced thermal properties. Its main characteristic was additional porous iron nozzle in the evaporator and the condenser to form a unique flowing pattern of MNF slug and vapor, and to magnetically shield the magnet attraction on MNF flowing. The results showed that an optimal thermal conductivity exists in the applied field of 200 Oe. Furthermore, the minor thermal performance of MNF at the condenser limited the thermal conductivity of the entire MNFHP, which was 1.6 times greater than that filled with water for the input power of 60 W. The feasibilities of an MNFHP with the magnetically enhanced heat transfer and the ability of vertical operation were proved for both a promising heat-dissipation device and the energy architecture integrated with an additional energy system. PMID:22716909

  3. Heat flux measurements of Tb{sub 3}M series (M=Co, Rh and Ru): Specific heat and magnetocaloric properties

    Energy Technology Data Exchange (ETDEWEB)

    Monteiro, J.C.B., E-mail: jolmiui@gmail.com [Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin, Campinas, SP 13083-859 (Brazil); Lombardi, G.A. [Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin, Campinas, SP 13083-859 (Brazil); Reis, R.D. dos [Max-Planck Institute for Chemical Physics of Solids, Nöthnitzer Str. 40, 01187 Dresden (Germany); Freitas, H.E.; Cardoso, L.P.; Mansanares, A.M.; Gandra, F.G. [Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin, Campinas, SP 13083-859 (Brazil)

    2016-12-15

    We report on the magnetic properties and magnetocaloric effect (MCE) for the Tb{sub 3}M series, with M=Co, Rh and Ru, obtained using a heat flux technique. The specific heat of Tb{sub 3}Co and Tb{sub 3}Rh are very similar, with a first order type transition occurring around 6 K below the magnetic ordering temperature without any corresponding feature on the magnetization. The slightly enhanced electronic specific heat, the Debye temperature around 150 K and the presence of the magnetic specific heat well above the ordering temperature are also characteristic of many other compounds of the R{sub 3}M family (R=Rare Earth). The specific heat for Tb{sub 3}Ru, however, presents two peaks at 37 K and 74 K. The magnetization shows that below the first peak the system presents an antiferromagnetic behavior and is paramagnetic above 74 K. We obtained a magnetocaloric effect for M=Co and Rh, −∆S=12 J/kg K, but for Tb{sub 3}Ru it is less than 3 J/kg K (μ{sub 0}∆H=5 T). We believe that the experimental results show that the MCE is directly related with the process of hybridization of the (R)5d-(M)d electrons that occurs in the R{sub 3}M materials.

  4. Flux line lattice melting transition in YBa2Cu3O6.94 observed in specific heat experiments

    International Nuclear Information System (INIS)

    Roulin, M.; Junod, A.; Walker, E.

    1996-01-01

    When a magnetic field penetrates a type II superconductor, it forms a lattice of thin quantized filaments called magnetic vortices. Resistance, magnetization, and neutron diffraction experiments have shown that the vortex lattice of high-temperature superconductors can melt along a line in the field-temperature plane. The calorimetric signature of melting on this line was observed in a high-accuracy adiabatic specific heat experiment performed on YBa 2 Cu 3 O 6.94 . The specific heat of the vortex liquid was greater than that of the vortex solid. 17 refs., 3 figs

  5. Magnetic nanowires and hyperthermia: How geometry and material affect heat production efficiency

    KAUST Repository

    Contreras, Maria F.; Zaher, A.; Perez, Jose E.; Ravasi, Timothy; Kosel, Jü rgen

    2015-01-01

    Magnetic hyperthermia, which refers to the production of heat by magnetic nanostructures under an alternating magnetic field (AMF), has been previously investigated with superparamagnetic nanobeads as a cancer therapy method. Magnetic nanowires (NWs

  6. Surface spin tunneling and heat dissipation in magnetic nanoparticles

    Science.gov (United States)

    Palakkal, Jasnamol P.; Obula Reddy, Chinna; Paulose, Ajeesh P.; Sankar, Cheriyedath Raj

    2018-03-01

    Quantum superparamagnetic state is observed in ultra-fine magnetic particles, which is often experimentally identified by a significant hike in magnetization towards low temperatures much below the superparamagnetic blocking temperature. Here, we report experimentally observed surface spin relaxation at low temperatures in hydrated magnesium ferrite nanoparticles of size range of about 5 nm. We observed time dependent oscillatory magnetization of the sample below 2.5 K, which is attributed to surface spin tunneling. Interestingly, we observed heat dissipation during the process by using an external thermometer.

  7. Development of the heat treatment system for the 40 T hybrid magnet superconducting outsert.

    Science.gov (United States)

    Chen, W G; Chen, Z M; Chen, Z Y; Huang, P C; He, P; Zhu, J W

    2011-10-01

    The heat treatment of Nb(3)Sn coil with the glass fabric insulation is one of the key and critical processes for the outsert solenoids of the 40 T hybrid magnet, which could be wound with cable-in-conduit conductors using the insulation-wind-and-react technique. The manufacturing of the large vertical type vacuum/Ar atmosphere-protection heat treatment system has been completed and recently installed in the High Magnetic Filed Laboratory, Chinese Academy of Sciences. The heat treatment system composed mainly the furnace, the purging gas supply system, the control system, the gas impurities monitoring system, and so on. At present, the regulation and testing of the heat treatment system has been successfully finished, and all of technical parameters meet or exceed specifications.

  8. Low temperature specific heat anomalies in melanins and tumor melanosomes

    Energy Technology Data Exchange (ETDEWEB)

    Mizutani, U [Carnegie--Mellon Univ., Pittsburgh; Massalski, T B; McGinness, J E; Corry, P M

    1976-02-12

    Human malignant melanoma cells obtained at autopsy were used. Data indicate that melanins exhibit a large linear term (50-200 erg g/sup -1/K/sup -2/) and that they seem to undergo a phase transition as indicated by the heat capacity near 1.9/sup 0/K. A table is presented to show low temperature specific heat data for melanin samples. The measurements include two anomalies, a transition and an unusually high linear contribution. (HLW)

  9. Electron heat flux dropouts in the solar wind: Evidence for interplanetary magnetic field reconnection?

    International Nuclear Information System (INIS)

    McComas, D.J.; Gosling, J.T.; Phillips, J.L.; Bame, S.J.; Luhmann, J.G.; Smith, E.J.

    1989-01-01

    Electron heat flux dropout events have been observed in the solar wind using the ISEE 3 plasma electron data set. These events manifest themselves as dropouts of the solar wind halo electrons which are normally found streaming outward along the local magnetic field. These dropouts leave nearly isotropic distributions of solar wind halo electrons, and consequently, the heat flux in these events is reduced to near the observational noise level. We have examined ISEE 3 data from shortly after launch (August 16, 1978) through the end of 1978 and identified 25 such events ranging in duration from 20 min to over 11 hours. Comparison with the ISEE 3 magnetometer data indicates that these intervals nearly always occur in conjunction with large rotations of the interplanetary magnetic field. Statistical analyses of the plasma and magnetic field data for the 25 dropout intervals indicate that heat flux dropouts generally occur in association with high plasma densities low plasma velocities, low ion and electron temperatures, and low magnetic field magnitudes. A second set of 25 intervals chosen specifically to lie at large field rotations, but at times at which not heat flux dropouts were observed, do not show these characteristic plalsma variations. This suggests that the dropout intervals comprise a unique set of events. Since the hot halo electrons normally found streaming outward from the Sun along the interplanetary magnetic field (the solar wind electron heat flux) are a result of direct magnetic connection to the hot solar corona, heat flux dropout intervals may indicate that the spacecraft is sampling plasma regimes which are magnetically disconnected from the Sun and instead are connected to the outer heliosphere at both ends

  10. Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes: Green's function approach

    Energy Technology Data Exchange (ETDEWEB)

    Mi, Bin-Zhou, E-mail: mbzfjerry2008@126.com [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China); Department of Physics, School of Mathematics and Physics, University of Science and Technology Beijing, Beijing 100083 (China); Zhai, Liang-Jun [The School of Mathematics and Physics, Jiangsu University of Technology, Changzhou 213001 (China); Hua, Ling-Ling [Department of Basic Curriculum, North China Institute of Science and Technology, Beijing 101601 (China)

    2016-01-15

    The effect of magnetic spin correlation on the thermodynamic properties of Heisenberg ferromagnetic single-walled nanotubes are comprehensively investigated by use of the double-time Green's function method. The influence of temperature, spin quantum number, diameter of the tube, anisotropy strength and external magnetic field to internal energy, free energy, and magnon specific heat are carefully calculated. Compared to the mean field approximation, the consideration of the magnetic correlation effect significantly improves the internal energy values at finite temperature, while it does not so near zero temperature, and this effect is related to the diameter of the tube, anisotropy strength, and spin quantum number. The magnetic correlation effect lowers the internal energy at finite temperature. As a natural consequence of the reduction of the internal energy, the specific heat is reduced, and the free energy is elevated. - Highlights: • Magnon specific heat and free energy of Heisenberg ferromagnetic single-walled nanotubes (HFM-SWNTs) are investigated. • The magnetic correlations effect has a considerable contribution to the thermodynamics properties of HFM-SWNTs. • Magnetic correlation effects are always to lower the internal energy at finite temperature. • At Curie point, magnetic correlation energy is much less than zero. • The peak values of magnon specific heat curves rise and shift right towards higher temperatures with the diameter of tubes, the anisotropy strength, and the spin quantum number rising.

  11. Nanomodified heat-accumulating materials controlled by a magnetic field

    Science.gov (United States)

    Shchegolkov, Alexander; Shchegolkov, Alexey; Dyachkova, Tatyana; Bodin, Nikolay; Semenov, Alexander

    2017-11-01

    The paper presents studies of nanomodified heat-accumulating materials controlled by a magnetic field. In order to obtain controlled heat-accumulating materials, synthetic motor oil CASTROL 0W30, ferromagnetic particles, CNTs and paraffin were used. Mechanically activated carbon nanotubes with ferromagnetic particles were used for the nanomodification of paraffin. Mechanoactivation ensured the production of ferromagnetic particles with an average particle size of 5 µm. Using an extrusion plant, a mixture of CNTs and ferromagnetic particles was introduced into the paraffin. Further, the nanomodified paraffin in a granular form was introduced into synthetic oil. To conduct experimental studies, a contactless method for measuring temperature was used. The thermal contact control with the help of the obtained nanomodified material is possible with a magnetic induction of 1250 mT, and a heat flux of about 74 kW/m2 is provided at the same time.

  12. Fluctuation-dissipation theorem for frequency-dependent specific heat

    DEFF Research Database (Denmark)

    Dyre, Jeppe; Nielsen, Johannes K.

    1996-01-01

    A derivation of the fluctuation-dissipation (FD) theorem for the frequency-dependent specific heat of a system described by a master equation is presented. The FD theorem is illustrated by a number of simple examples, including a system described by a linear Langevin equation, a two-level system......, and a system described by the energy master equation. It is shown that for two quite different models with low-energy cutoffs—a collection of two-level systems and a system described by the energy master equation—the frequency-dependent specific heat in dimensionless units becomes universal at low temperatures......, i.e., independent of both energy distribution and temperature. These two models give almost the same universal frequency-dependent specific heat, which compares favorably to experiments on supercooled alcohols....

  13. Superconductivity and specific heat of titanium base A15 alloys

    International Nuclear Information System (INIS)

    Junod, A.; Flukiger, R.; Muller, J.

    1976-01-01

    Experimental data on the superconducting transition temperature, and low temperature specific heat, together with X-ray investigations, are reported for binary and pseudo-binary compounds of Ti with the A15-type structure. A 'true' relative maximum of the coefficient of the electronic specific heat, γ, as well as the superconducting transition temperature, Tsub(c), occurs in the Tisub(3)Irsub(1-x)Ptsub(x) system near x = 0.2. Tisub(3)Irsub(0.8)Ptsub(0.2) shows the lowest Debye temperature, theta 0 , of all A15-type compounds known to date. The anomalous temperature dependence of the lattice specific heat may be reproduced by a model phonon spectrum similar to that of Nb 3 Sn. (author)

  14. A helium based pulsating heat pipe for superconducting magnets

    Science.gov (United States)

    Fonseca, Luis Diego; Miller, Franklin; Pfotenhauer, John

    2014-01-01

    This study was inspired to investigate an alternative cooling system using a helium-based pulsating heat pipes (PHP), for low temperature superconducting magnets. In addition, the same approach can be used for exploring other low temperature applications. The advantages of PHP for transferring heat and smoothing temperature profiles in various room temperature applications have been explored for the past 20 years. An experimental apparatus has been designed, fabricated and operated and is primarily composed of an evaporator and a condenser; in which both are thermally connected by a closed loop capillary tubing. The main goal is to measure the heat transfer properties of this device using helium as the working fluid. The evaporator end of the PHP is comprised of a copper winding in which heat loads up to 10 watts are generated, while the condenser is isothermal and can reach 4.2 K via a two stage Sumitomo RDK408A2 GM cryocooler. Various experimental design features are highlighted. Additionally, performance results in the form of heat transfer and temperature characteristics are provided as a function of average condenser temperature, PHP fill ratio, and evaporator heat load. Results are summarized in the form of a dimensionless correlation and compared to room temperature systems. Implications for superconducting magnet stability are highlighted.

  15. Investigation of heat distribution during magnetic heating treatment using a polyurethane–ferrofluid phantom-model

    International Nuclear Information System (INIS)

    Henrich, F.; Rahn, H.; Odenbach, S.

    2014-01-01

    Magnetic heating treatment can be used as an adjuvant treatment for cancer therapy. In this therapy, magnetic nanoparticles are enriched inside the tumour and exposed to an alternating magnetic field. Due to magnetic losses the temperature in the tumour rises. The resulting temperature profile inside the tumour is useful for the therapeutic success. In this context heat transfer between tissue with nanoparticles and tissue without nanoparticles is a highly important feature which is actually not understood in detail. In order to investigate this, a phantom has been created which can be used to measure the temperature profile around a region enriched with magnetic nanoparticles. This phantom is composed of a material, which has similar thermal conductivity as human tissue. A tempered water bath surrounds the phantom to establish a constant surrounding temperature simulating the heat sink provided by the human body in a real therapeutic application. It has been found that even at a low concentration of magnetic nanoparticles around 13 mg/ml, sufficient heating of the enriched region can be achieved. Moreover it has been observed that the temperature drops rapidly in the material surrounding the enriched region. Corresponding numerical investigations provide a basis for future recalculations of the temperature inside the tumour using temperature data obtained in the surrounding tissue. - Highlights: • The temperature profile by magnetic hyperthermia was examined. • A model was built to get a deeper understanding of the temperature profile. • The temperature profile of the model inside magnetic fields was measured. • Based on the model a simulation of the temperature profile was performed. • The simulated temperature profile agreed well with the measured profile

  16. Anomalous Schottky specific heat and structural distortion in ferromagnetic PrAl2.

    Science.gov (United States)

    Pathak, Arjun K; Paudyal, D; Mudryk, Y; Gschneidner, K A; Pecharsky, V K

    2013-05-03

    Unique from other rare earth dialuminides, PrAl(2) undergoes a cubic to tetragonal distortion below T = 30 K in a zero magnetic field, but the system recovers its cubic symmetry upon the application of an external magnetic field of 10 kOe via a lifting of the 4f crystal field splitting. The nuclear Schottky specific heat in PrAl(2) is anomalously high compared to that of pure Pr metal. First principles calculations reveal that the 4f crystal field splitting in the tetragonally distorted phase of PrAl(2) underpins the observed unusual low temperature phenomena.

  17. Large specific absorption rates in the magnetic hyperthermia properties of metallic iron nanocubes

    Energy Technology Data Exchange (ETDEWEB)

    Mehdaoui, B.; Meffre, A.; Lacroix, L.-M. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Carrey, J., E-mail: julian.carrey@insa-toulouse.f [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Lachaize, S. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Gougeon, M. [Institut CARNOT-CIRIMAT-UMR 5085, Batiment 2R1, 118 route de Narbonne, F-31062 Toulouse (France); Respaud, M. [Universite de Toulouse, INSA, UPS, LPCNO (Laboratoire de Physique et Chimie des Nano-Objets), 135 avenue de Rangueil, F-31077 Toulouse (France); CNRS, UMR 5215, LPCNO, F-31077 Toulouse (France); Chaudret, B. [Laboratoire de Chimie de Coordination-CNRS, 205 rte de Narbonne, 31077 Toulouse cedex 4 (France)

    2010-10-15

    We report on the magnetic hyperthermia properties of chemically synthesized ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the saturation magnetization of bulk iron. The specific absorption rate measured on 16 nm nanocubes is 1690{+-}160 W/g at 300 kHz and 66 mT. This corresponds to specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in other systems. A way to quantify the degree of optimization of any system with respect to hyperthermia applications is proposed. Applied here, this method shows that our nanoparticles are not fully optimized, probably due to the strong influence of magnetic interactions on their magnetic response. Once protected from oxidation and further optimized, such nano-objects could constitute efficient magnetic cores for biomedical applications requiring very large heating power.

  18. Specific heat of the simple-cubic Ising model

    NARCIS (Netherlands)

    Feng, X.; Blöte, H.W.J.

    2010-01-01

    We provide an expression quantitatively describing the specific heat of the Ising model on the simple-cubic lattice in the critical region. This expression is based on finite-size scaling of numerical results obtained by means of a Monte Carlo method. It agrees satisfactorily with series expansions

  19. Measurement of the specific heat capacity of graphite

    Energy Technology Data Exchange (ETDEWEB)

    Picard, S.; Burns, D.T.; Roger, P

    2006-01-15

    With the objective of implementing graphite calorimetry at the BIPM to measure absorbed dose, an experimental assembly has recently been constructed to measure the specific heat capacity of graphite. A status description of the apparatus and results from the first measurements are given. The outcome is discussed and the experimental uncertainty is reviewed. (authors)

  20. Measurement of the specific heat capacity of graphite

    International Nuclear Information System (INIS)

    Picard, S.; Burns, D.T.; Roger, P.

    2006-01-01

    With the objective of implementing graphite calorimetry at the BIPM to measure absorbed dose, an experimental assembly has recently been constructed to measure the specific heat capacity of graphite. A status description of the apparatus and results from the first measurements are given. The outcome is discussed and the experimental uncertainty is reviewed. (authors)

  1. Transport properties and specific heat of UTe and USb

    International Nuclear Information System (INIS)

    Ochiai, A.; Suzuki, Y.; Shikama, T.; Suzuki, K.; Hotta, E.; Haga, Y.; Suzuki, T.

    1994-01-01

    Uranium monochalcogenides and monopnictides crystallize in the NaCl-type structure and exhibit ferromagnetic and antiferromagnetic order, respectively. These series reveal interesting properties such as Kondo behavior of UTe. However, such interesting properties are much sample dependent. We grew single crystals of USb and UTe with high purity using the Bridgman technique, and measured transport properties and specific heat. ((orig.))

  2. Specific heat of Cr-based semimagnetic semiconductors

    NARCIS (Netherlands)

    Twardowski, A.; Eggenkamp, P.J.T.; Mac, W.; Swagten, H.J.M.; Demianiuk, M.

    1993-01-01

    Specific heat of ZnCrSe and ZnCrS was measured for 1.5

  3. Parallel heat transport in integrable and chaotic magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Castillo-Negrete, D. del; Chacon, L. [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-8071 (United States)

    2012-05-15

    The study of transport in magnetized plasmas is a problem of fundamental interest in controlled fusion, space plasmas, and astrophysics research. Three issues make this problem particularly challenging: (i) The extreme anisotropy between the parallel (i.e., along the magnetic field), {chi}{sub ||} , and the perpendicular, {chi}{sub Up-Tack }, conductivities ({chi}{sub ||} /{chi}{sub Up-Tack} may exceed 10{sup 10} in fusion plasmas); (ii) Nonlocal parallel transport in the limit of small collisionality; and (iii) Magnetic field lines chaos which in general complicates (and may preclude) the construction of magnetic field line coordinates. Motivated by these issues, we present a Lagrangian Green's function method to solve the local and non-local parallel transport equation applicable to integrable and chaotic magnetic fields in arbitrary geometry. The method avoids by construction the numerical pollution issues of grid-based algorithms. The potential of the approach is demonstrated with nontrivial applications to integrable (magnetic island), weakly chaotic (Devil's staircase), and fully chaotic magnetic field configurations. For the latter, numerical solutions of the parallel heat transport equation show that the effective radial transport, with local and non-local parallel closures, is non-diffusive, thus casting doubts on the applicability of quasilinear diffusion descriptions. General conditions for the existence of non-diffusive, multivalued flux-gradient relations in the temperature evolution are derived.

  4. Local and Nonlocal Parallel Heat Transport in General Magnetic Fields

    International Nuclear Information System (INIS)

    Castillo-Negrete, D. del; Chacon, L.

    2011-01-01

    A novel approach for the study of parallel transport in magnetized plasmas is presented. The method avoids numerical pollution issues of grid-based formulations and applies to integrable and chaotic magnetic fields with local or nonlocal parallel closures. In weakly chaotic fields, the method gives the fractal structure of the devil's staircase radial temperature profile. In fully chaotic fields, the temperature exhibits self-similar spatiotemporal evolution with a stretched-exponential scaling function for local closures and an algebraically decaying one for nonlocal closures. It is shown that, for both closures, the effective radial heat transport is incompatible with the quasilinear diffusion model.

  5. Negative specific heat with trapped ultracold quantum gases

    Science.gov (United States)

    Strzys, M. P.; Anglin, J. R.

    2014-01-01

    The second law of thermodynamics normally prescribes that heat tends to disperse, but in certain cases it instead implies that heat will spontaneously concentrate. The spontaneous formation of stars out of cold cosmic nebulae, without which the universe would be dark and dead, is an example of this phenomenon. Here we show that the counter-intuitive thermodynamics of spontaneous heat concentration can be studied experimentally with trapped quantum gases, by using optical lattice potentials to realize weakly coupled arrays of simple dynamical subsystems, so that under the standard assumptions of statistical mechanics, the behavior of the whole system can be predicted from ensemble properties of the isolated components. A naive application of the standard statistical mechanical formalism then identifies the subsystem excitations as heat in this case, but predicts them to share the peculiar property of self-gravitating protostars, of having negative micro-canonical specific heat. Numerical solution of real-time evolution equations confirms the spontaneous concentration of heat in such arrays, with initially dispersed energy condensing quickly into dense ‘droplets’. Analysis of the nonlinear dynamics in adiabatic terms allows it to be related to familiar modulational instabilities. The model thus provides an example of a dictionary mesoscopic system, in which the same non-trivial phenomenon can be understood in both thermodynamical and mechanical terms.

  6. Magnetic properties of atmospheric PMx in a small settlement during heating and non-heating season

    Science.gov (United States)

    Petrovsky, E.; Kotlik, B.; Zboril, R.; Kapicka, A.; Grison, H.

    2012-04-01

    Magnetic properties of environmental samples can serve as fast and relatively cheap proxy method to investigate occurrence of iron oxides. These methods are very sensitive in detecting strongly magnetic compounds such as magnetite and maghemite and can reveal concentration and assess grain-size distribution of these minerals. This information can be significant in estimating e.g. the source of pollutants, monitoring pollution load, or investigating seasonal and climatic effects. We studied magnetic properties of PM1, PM2.5 and PM10, collected over 32-48 hours in a small settlement in south Bohemia during heating and non-heating season. The site is rather remote, with negligible traffic and industrial contributions to air pollution. Thus, the suggested seasonal effect should be dominantly due to local (domestic) heating, burning wood or coal. In our contribution we show typical differences in PMx concentration, which is much higher in the winter (heating) sample, accompanied by SEM analyses and magnetic data oriented on concentration and grain-size distribution of magnetite/maghemite particles. While concentration of Fe-oxides does not vary that much, significant seasonal differences were observed in composition and grain-size distribution, reflecting different sources of the dust particles.

  7. Permanent magnet design for magnetic heat pumps using total cost minimization

    Science.gov (United States)

    Teyber, R.; Trevizoli, P. V.; Christiaanse, T. V.; Govindappa, P.; Niknia, I.; Rowe, A.

    2017-11-01

    The active magnetic regenerator (AMR) is an attractive technology for efficient heat pumps and cooling systems. The costs associated with a permanent magnet for near room temperature applications are a central issue which must be solved for broad market implementation. To address this problem, we present a permanent magnet topology optimization to minimize the total cost of cooling using a thermoeconomic cost-rate balance coupled with an AMR model. A genetic algorithm identifies cost-minimizing magnet topologies. For a fixed temperature span of 15 K and 4.2 kg of gadolinium, the optimal magnet configuration provides 3.3 kW of cooling power with a second law efficiency (ηII) of 0.33 using 16.3 kg of permanent magnet material.

  8. Assessment of Vascular Stent Heating with Repetitive Transcranial Magnetic Stimulation.

    Science.gov (United States)

    Varnerin, Nicole; Mirando, David; Potter-Baker, Kelsey A; Cardenas, Jesus; Cunningham, David A; Sankarasubramanian, Vishwanath; Beall, Erik; Plow, Ela B

    2017-05-01

    A high proportion of patients with stroke do not qualify for repetitive transcranial magnetic stimulation (rTMS) clinical studies due to the presence of metallic stents. The ultimate concern is that any metal could become heated due to eddy currents. However, to date, no clinical safety data are available regarding the risk of metallic stents heating with rTMS. We tested the safety of common rTMS protocols (1 Hz and 10 Hz) with stents used commonly in stroke, nitinol and elgiloy. In our method, stents were tested in gelled saline at 2 different locations: at the center and at the lobe of the coil. In addition, at each location, stent heating was evaluated in 3 different orientations: parallel to the long axis of coil, parallel to the short axis of the coil, and perpendicular to the plane of the coil. We found that stents did not heat to more than 1°C with either 1 Hz rTMS or 10 Hz rTMS in any configuration or orientation. Heating in general was greater at the lobe when the stent was oriented perpendicularly. Our study represents a new method for ex vivo quantification of stent heating. We have found that heating of stents was well below the Food and Drug Administration standards of 2°C. Thus, our study paves the way for in vivo testing of rTMS (≤10 Hz) in the presence of implanted magnetic resonance imaging-compatible stents in animal studies. When planning human safety studies though, geometry, orientation, and location relative to the coil would be important to consider as well. Copyright © 2017 National Stroke Association. Published by Elsevier Inc. All rights reserved.

  9. Chiral heat wave and mixing of magnetic, vortical and heat waves in chiral media

    International Nuclear Information System (INIS)

    Chernodub, M.N.

    2016-01-01

    We show that a hot rotating fluid of relativistic chiral fermions possesses a new gapless collective mode associated with coherent propagation of energy density and chiral density waves along the axis of rotation. This mode, which we call the Chiral Heat Wave, emerges due to a mixed gauge-gravitational anomaly. At finite density the Chiral Heat Wave couples to the Chiral Vortical Wave while in the presence of an external magnetic field it mixes with the Chiral Magnetic Wave. The coupling of the Chiral Magnetic and Chiral Vortical Waves is also demonstrated. We find that the coupled waves — which are coherent fluctuations of the vector, axial and energy currents — have generally different velocities compared to the velocities of the individual waves.

  10. Heat loss mechanisms in a measurement of specific heat capacity of graphite

    International Nuclear Information System (INIS)

    Shipley, D.R.; Duane, S.

    1996-01-01

    Absorbed dose to graphite in electron beams with nominal energies in the range 3-20 MeV is determined by measuring the temperature rise in the core of a primary standard graphite calorimeter. This temperature rise is related to absorbed dose by a separate measurement of the specific heat capacity of the graphite core. There is, however, a small but significant amount of heat loss from the sample in the determination of specific heat capacity and corrections for these losses are required. This report discusses the sources of heat loss in the measurements and, where possible, provides estimates for the magnitude of these losses. For those mechanisms which are significant, a more realistic model of the measurement system is analysed and corrections for the losses are provided. (UK)

  11. Novel magnetic heating probe for multimodal cancer treatment.

    Science.gov (United States)

    Kan-Dapaah, Kwabena; Rahbar, Nima; Soboyejo, Wole

    2015-05-01

    Multifunctional materials consisting of polymers and magnetic nanoparticles (MNPs) are highly sought after in the field of biomedical engineering. These materials offer new opportunities for the development of novel cancer treatment modalities that can increase the efficacy of cancer therapy. In this paper, a novel probe for multimodal cancer treatment is proposed and analyzed. The probe is essentially a cannula with two main parts: a distal heat generating tip made of a magnetic nanocomposite and a proximal insulated shaft. A description of the concept and functional operations of the probe is presented. In an effort to assess its feasibility, the authors evaluated the ability of probe tip (made of PMMA-Fe3O4 nanocomposite) to generate heat in biological tissue using alternating magnetic field (AMF) parameters (field strength and frequency) that are acceptable for human use. Heat generation by MNPs was determined using the linear response theory. The effects of Fe3O4 volume fraction on heat generation as well as treatment time on the thermal dose were studied. The finite element method model was tested for its validity using an analytical model. Lesions were revealed to have an ellipsoidal shape and their sizes were affected by treatment time. However, their shapes remained unchanged. The comparison with the analytical model showed reasonably a good agreement to within 2%. Furthermore, the authors' numerical predictions also showed reasonable agreement with the experimental results previously reported in the literature. The authors' predictions demonstrate the feasibility of their novel probe to achieve reasonable lesion sizes, during hyperthermic or ablative heating using AMF parameters (field strength and frequency) that are acceptable for human use.

  12. Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, Y., E-mail: nano@tsutmb.ru [M.V. Lomonosov Moscow State University, School of Chemistry (Russian Federation); Golovin, D. [G.R. Derzhavin Tambov State University (Russian Federation); Klyachko, N.; Majouga, A.; Kabanov, A. [M.V. Lomonosov Moscow State University, School of Chemistry (Russian Federation)

    2017-02-15

    Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

  13. Modeling drug release from functionalized magnetic nanoparticles actuated by non-heating low frequency magnetic field

    International Nuclear Information System (INIS)

    Golovin, Y.; Golovin, D.; Klyachko, N.; Majouga, A.; Kabanov, A.

    2017-01-01

    Various plausible acceleration mechanisms of drug release from nanocarriers composed of a single-domain magnetic nanoparticle core with attached long macromolecule chains activated by low frequency non-heating alternating magnetic field (AMF) are discussed. The most important system characteristics affecting the AMF exposure impact are determined. Impact of several reasonable mechanisms is estimated analytically or obtained using numerical modeling. Some conditions providing manifold release acceleration as a result from exposure in AMF are found.

  14. Nanocalorimeter platform for in situ specific heat measurements and x-ray diffraction at low temperature

    Science.gov (United States)

    Willa, K.; Diao, Z.; Campanini, D.; Welp, U.; Divan, R.; Hudl, M.; Islam, Z.; Kwok, W.-K.; Rydh, A.

    2017-12-01

    Recent advances in electronics and nanofabrication have enabled membrane-based nanocalorimetry for measurements of the specific heat of microgram-sized samples. We have integrated a nanocalorimeter platform into a 4.5 T split-pair vertical-field magnet to allow for the simultaneous measurement of the specific heat and x-ray scattering in magnetic fields and at temperatures as low as 4 K. This multi-modal approach empowers researchers to directly correlate scattering experiments with insights from thermodynamic properties including structural, electronic, orbital, and magnetic phase transitions. The use of a nanocalorimeter sample platform enables numerous technical advantages: precise measurement and control of the sample temperature, quantification of beam heating effects, fast and precise positioning of the sample in the x-ray beam, and fast acquisition of x-ray scans over a wide temperature range without the need for time-consuming re-centering and re-alignment. Furthermore, on an YBa2Cu3O7-δ crystal and a copper foil, we demonstrate a novel approach to x-ray absorption spectroscopy by monitoring the change in sample temperature as a function of incident photon energy. Finally, we illustrate the new insights that can be gained from in situ structural and thermodynamic measurements by investigating the superheated state occurring at the first-order magneto-elastic phase transition of Fe2P, a material that is of interest for magnetocaloric applications.

  15. Specific Heat Capacity of Alloy 690 for Simulating Neutron Irradiation

    International Nuclear Information System (INIS)

    Park, Dae Gyu; Kim, Hee Moon; Song, Woong Sub; Baik, Seung Je; Joo, Young Sun; Ahn, Sang Bok; Park, Jin Seok; Lee, Won Jae; Ryu, Woo Seok

    2011-01-01

    The KAERI(Korea Atomic Energy Research Institute) is developing new type of nuclear reactor, so called 'SMART'(System Integrated Modular Advanced Reactor) which has many features of small power and system integrated modular type. Alloy 690 was selected as the candidate material for the heat exchanger tube of the steam generator of SMART. The SMART R and D is now facing the stage of engineering verification and approval of standard design to apply to DEMO reactors. Therefore, the material performance under the relevant environment is required to be evaluated. The important material performance issues are mechanical properties i.e. (fracture toughness, tensile and hardness) and thermal properties i.e. (thermal diffusivity, specific heat capacity and thermal conductivity) for which the engineering database is necessary to design a steam generator. However, the neutron post irradiation characteristics of the alloy 690 are barely known. As a result, PIE(Post Irradiation Examination) of thermal properties are planed and performed successfully. But specific heat capacity measurement is not performed because of not having proper test system for irradiated materials. Therefore in order to verify the effect of neutron irradiation for alloy 690, simulation method is adopted. In general, high energy neutron bombardment in material bring about lattice defects i.e. void, pore and dislocation. Dominant factor to impact to heat capacity is mainly dislocation in material. Therefore, simulation of neutron irradiation is devised by material rolling method in order to make artificial dislocation in alloy 690 as same effect of neutron irradiation. After preparing test specimens, heat capacity measurements are performed and results are compared with rolled materials and un-rolled materials to verify the effect of neutron irradiation simulation. Main interest of simulation is that heat capacity value is changed by neutron irradiation

  16. Induction heating of rotating nonmagnetic billet in magnetic field produced by high-parameter permanent magnets

    Directory of Open Access Journals (Sweden)

    Ivo Doležel

    2014-04-01

    Full Text Available An advanced way of induction heating of nonmagnetic billets is discussed and modeled. The billet rotates in a stationary magnetic field produced by unmoving high-parameter permanent magnets fixed on magnetic circuit of an appropriate shape. The mathematical model of the problem consisting of two coupled partial differential equations is solved numerically, in the monolithic formulation. Computations are carried out using our own code Agros2D based on a fully adaptive higher-order finite element method. The most important results are verified experimentally on our own laboratory device.

  17. Non Debye approximation on specific heat of solids

    Science.gov (United States)

    Bhattacharjee, Ruma; Das, Anamika; Sarkar, A.

    2018-05-01

    A simple non Debye frequency spectrum is proposed. The normalized frequency spectrum is compared to that of Debye spectrum. The proposed spectrum, provides a good account of low frequency phonon density of states, which gives a linear temperature variation at low temperature in contrast to Debye T3 law. It has been analyzed that the proposed model provides a good account of excess specific heat for nanostructure solid.

  18. Specific heat of V3GaH/sub x/

    International Nuclear Information System (INIS)

    Cort, B.; Stewart, G.R.; Huang, S.Z.; Meng, R.L.; Chu, C.W.

    1981-01-01

    Specific-heat measurements have been made on V 3 GaH/sub x/ for x = 0, 0.2, 1.4, and 1.9 in the temperature range 1.2--20 K. In addition to increased lattice parameter and depressed transition temperature with increased hydrogen concentrations, the Debye temperature increases and the electronic density of states drops, both dramatically. Decreased electron-phonon coupling is also indicated with hydrogenation

  19. Review of heat transfer problems associated with magnetically-confined fusion reactor concepts

    International Nuclear Information System (INIS)

    Hoffman, M.A.; Werner, R.W.; Carlson, G.A.; Cornish, D.N.

    1976-01-01

    Conceptual design studies of possible fusion reactor configurations have revealed a host of interesting and sometimes extremely difficult heat transfer problems. The general requirements imposed on the coolant system for heat removal of the thermonuclear power from the reactor are discussed. In particular, the constraints imposed by the fusion plasma, neutronics, structure and magnetic field environment are described with emphasis on those aspects which are unusual or unique to fusion reactors. Then the particular heat transfer characteristics of various possible coolants including lithium, flibe, boiling alkali metals, and helium are discussed in the context of these general fusion reactor requirements. Some specific areas where further experimental and/or theoretical work is necessary are listed for each coolant along with references to the pertinent research already accomplished. Specialized heat transfer problems of the plasma injection and removal systems are also described. Finally, the challenging heat transfer problems associated with the superconducting magnets are reviewed, and once again some of the key unsolved heat transfer problems are enumerated

  20. Specific heat of FeSe: Two gaps with different anisotropy in superconducting state

    Science.gov (United States)

    Muratov, A. V.; Sadakov, A. V.; Gavrilkin, S. Yu.; Prishchepa, A. R.; Epifanova, G. S.; Chareev, D. A.; Pudalov, V. M.

    2018-05-01

    We present detailed study of specific heat of FeSe single crystals with critical temperature Tc = 8.45 K at 0.4 - 200 K in magnetic fields 0 - 9 T. Analysis of the electronic specific heat at low temperatures shows the coexistence of isotropic s-wave gap and strongly anisotropic extended s-wave gap without nodes. It was found two possibilities of superconducting gap parameters which give equally description of experimental data: (i) two gaps with approximately equal amplitudes and weight contribution to specific heat: isotropic Δ1 = 1.7 meV (2Δ1 /kBTc =4.7) and anisotropic gap with the amplitude Δ2max = 1.8 meV (2 Δ2max /kBTc =4.9 and anisotropy parameter m = 0.85); (ii) two gaps with substantially different values: isotropic large gap Δ1 = 1.65 meV (2Δ1 /kBTc = 4.52) and anisotropic small gap Δ2max = 0.75 meV (2Δ2max /kBTc = 2) with anisotropy parameter m = 0.71 . These results are confirmed by the field behavior of the residual electronic specific heat γr.

  1. High-field specific heats of A15 V3Si and Nb3Sn

    Science.gov (United States)

    Stewart, G. R.; Brandt, B. L.

    1984-04-01

    In order to further understand the anomalous behavior of the specific heat of Nb3Sn in an 18-T magnetic field discovered by Stewart, Cort, and Webb [Phys. Rev. B 24, 3841 (1981)], we have performed specific-heat measurements on a different sample of Nb3Sn at lower fields both in the normal and mixed states, as well as measurement to 19 T on both transforming and nontransforming V3Si. The high-field data for V3Si indicate that this material behaves quite normally, and that γtransJunod and Muller [Solid State Commun. 36, 721 (1980)]. Nb3Sn, however, remains anomalous, with both the same "kink" in the normal-state field data as observed by Stewart, Cort, and Webb (although at a slightly higher temperature) and unusual mixed-state behavior. The mixed-state specific heat of the V3Si samples is as expected, based on earlier work on the mixed-state specific heat of V and Nb.

  2. Generic Guide Specification for Geothermal Heat Pump Systems

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, WKT

    2000-04-12

    The attached Geothermal (Ground-Source) Heat Pump (GHP) Guide Specifications have been developed by Oak Ridge National Laboratory (ORNL) with the intent to assist federal agency sites and engineers in the preparation of construction specifications for GHP projects. These specifications have been developed in the industry-standard Construction Specification Institute (CSI) format and cover several of the most popular members of the family of GHP systems. These guide specifications are applicable to projects whether the financing is with conventional appropriations, arranged by GHP specialty ESCOs under the U.S. Department of Energy's Technology-Specific GHP Super ESPCs, arranged by utilities under Utility Energy Service Contracts (UESCs) or arranged by generalist ESCOs under the various regional ESPCs. These specifications can provide several benefits to the end user that will help ensure successful GHP system installations. GHP guide specifications will help to streamline the specification development, review, and approval process because the architecture and engineering (AE) firm will be working from the familiar CSI format instead of developing the specifications from other sources. The guide specifications help to provide uniformity, standardization, and consistency in both the construction specifications and system installations across multiple federal sites. This standardization can provide future benefits to the federal sites in respect to both maintenance and operations. GHP guide specifications can help to ensure that the agency is getting its money's worth from the GHP system by preventing the use of marginal or inferior components and equipment. The agency and its AE do not have to start from scratch when developing specifications and can use the specification as a template and/or a checklist in developing both the design and the contract documents. The guide specifications can save project costs by reducing the engineering effort required

  3. Curie Temperature and Microstructural Changes Due to the Heating Treatment of Magnetic Amorphous Materials

    Directory of Open Access Journals (Sweden)

    Gondro J.

    2016-03-01

    Full Text Available Three distinct alloys: Fe86Zr7Nb1Cu1B5, Fe82Zr7Nb2Cu1B8, and Fe81Pt5Zr7Nb1Cu1B5 were characterized both magnetically and structurally. The samples, obtained with spinning roller method as a ribbons 3 mm in width and 20 μm thick, were investigated as-quenched and after each step of a multi steps heating treatment procedure. Each sample was annealed at four steps, fifteen minutes at every temperature, starting from 573K+600K up to +700K depending on type of alloy. Mössbauer spectroscopy data and transmission electron microscope (HRE M pictures confirmed that the as-quenched samples are fully amorphous. This is not changed after the first stages of treatment heating leads to a reduction of free volumes. The heating treatment has a great influence on the magnetic susceptibilities. The treatment up to 600K improves soft magnetic properties: an χ increase was observed, from about 400 to almost 1000 for the samples of alloys without Pt, and from about 200 to 450 at maximum, for the Fe81Pt5Zr7Nb1Cu1B5. Further heating, at more elevated temperatures, leads to magnetic hardening of the samples. Curie temperatures, established from the location of Hopkinson’s maxima on the χ(T curve are in very good agreement with those obtained from the data of specific magnetization, σ(T, measured in a field of 0.75T. As a critical parameter β was chosen to be equal 0.36 for these calculations, it confirmed that the alloys may be considered as ferromagnetic of Heisenberg type. Heating treatment resulted in decreasing of TC. These changes are within a range of several K.

  4. Specific heat of holmium and YNi2B2C. Criticalbehaviour and superconducting properties

    International Nuclear Information System (INIS)

    Bekkali, Abdelhakim

    2010-01-01

    Object of the thesis is the study of the specific heat of holmium and YNi 2 B 2 C in the temperature ranges from 50 to 200 KI respectively from 380 mK to 20 K in magnetic fields up to 9 T. In the present thesis the criticalbehaviour of YNi 2 B 2 C and properties of the superconducting state of tne non-magnetic rare-earth nickel borocarbide YNi 2 B 2 C are studied by means of a self-developed measurement apparatur of the specific heat using the quasi-adiabatic heating-pulse method as well as of holmium by means of the relaxation method. In this thesis reliable statements about the critical exponents on monocrystalline holmium could be made. The study on holmium proves that the critical behaviour of the specific heats cannot be described in the framework of the predictions of the chiral universality classes. By means of measurements of the specific heat in this thesis could be confirmed that YNi 2 B 2 C is a multiband superconductor. The positive curvature of the boundary line below T c in the phase diagram yields a first hint to the many-band character of YNI 2 B 2 C. In the zero-field the electronic specific heat in the superconducting state c es (T) can be not explained in the framework of the pure BCS theory. At low temperatures a residual contribution by normally conducting electrons could be detected, which hints to a not completely opened energy gap. A possible explanation would be that a band (or several bands) with low charge-carrier concentration not contribute to the superconductivity. This result agrees with de Haas-van Alphen measurements on isostructural superconducting LuNi 2 B 2 C monocrystals, which suggest the many-band character of the superconductivity as well as a vanishing energy gap in one band. The fluctuation behaviour of the specific heat of YNi 2 B 2 C in the neighbourhood of the superconducting-normally conducting transition agrees well with that of the 3D-XY model. [de

  5. Magnetic pumping as a source of particle heating

    Science.gov (United States)

    Lichko, Emily; Egedal, Jan; Daughton, William; Kasper, Justin

    2017-10-01

    Magnetic pumping is a means of heating plasmas for both fusion and astrophysical applications. In this study a magnetic pumping model is developed as a possible explanation for the heating and the generation of power-law distribution functions observed in the solar wind plasma. In most previous studies turbulent energy is only dissipated at microscopic kinetic scales. In contrast, magnetic pumping energizes the particles through the largest scale turbulent fluctuations, thus bypassing the energy cascade. Kinetic simulations are applied to verify these analytic predictions. Previous results for the one-dimensional model, as well as initial results for a two-dimensional model which includes the effects of trapped and passing particles are presented. Preliminary results of the presence of this mechanism in the bow shock region, using spacecraft data from the Magnetospheric Multiscale mission, are presented as well. This research was conducted with support from National Defense Science and Engineering Graduate (NDSEG) Fellowship, 32 CFR 168, as well as from NSF Award 1404166 and NASA award NNX15AJ73G.

  6. Localized Electron Heating by Strong Guide-Field Magnetic Reconnection

    Science.gov (United States)

    Guo, Xuehan; Sugawara, Takumichi; Inomoto, Michiaki; Yamasaki, Kotaro; Ono, Yasushi; UTST Team

    2015-11-01

    Localized electron heating of magnetic reconnection was studied under strong guide-field (typically Bt 15Bp) using two merging spherical tokamak plasmas in Univ. Tokyo Spherical Tokamak (UTST) experiment. Our new slide-type two-dimensional Thomson scattering system documented for the first time the electron heating localized around the X-point. The region of high electron temperature, which is perpendicular to the magnetic field, was found to have a round shape with radius of 2 [cm]. Also, it was localized around the X-point and does not agree with that of energy dissipation term Et .jt . When we include a guide-field effect term Bt / (Bp + αBt) for Et .jt where α =√{ (vin2 +vout2) /v∥2 } , the energy dissipation area becomes localized around the X-point, suggesting that the electrons are accelerated by the reconnection electric field parallel to the magnetic field and thermalized around the X-point. This work was supported by JSPS A3 Foresight Program ``Innovative Tokamak Plasma Startup and Current Drive in Spherical Torus,'' a Grant-in-Aid from the Japan Society for the Promotion of Science (JSPS) Fellows 15J03758.

  7. Low-temperature specific heat of the 'nearly ferromagnetic' amorphous alloy Ysub(0.22)Nisub(0.78)

    International Nuclear Information System (INIS)

    Garoche, P.; Veyssie, J.J.; Lienard, A.; Rebouillat, J.P.

    1979-01-01

    Results of specific heat measurements, between 0.3K and 10 K in magnetic fields up to 75 kOe, on the 'nearly ferromagnetic' amorphous alloy Ysub(0.22)Nisub(0.78) are reported. The results, especially the magnetic field dependence, exclude any appreciable contribution from uniform paramagnons. In contrast a quantitative analysis is obtained in terms of superparamagnetic clusters, demonstrating that the onset of ferromagnetism, as a function of concentration, is inhomogeneous in this amorphous metallic system. (author)

  8. Design of cryogenic heat exchangers for a superconducting magnet

    International Nuclear Information System (INIS)

    Chrusciel, W.A.; Tao, B.Y.; Ventura, S.A.

    1976-01-01

    Computer programs were written to design and simulate the behavior of three heat exchangers for cooling supercritical helium to approximately 4.3 0 K at 4 atm. Helium, at 1, 3, or 5 gm/sec, is cooled by passing it through 0.635-cm-diam copper tubing immersed in a liquid nitrogen bath, through a copper, concentric tube, counter-current heat exchanger, and then through 0.635-cm copper tubing immersed in a liquid helium bath. The helium then enters a superconducting test magnet and finally passes through the annulus of the countercurrent exchanger before venting to the atmosphere. Several acceptable designs are presented that meet design and space limitations

  9. Ion heating due to rotation and collision in magnetized plasma

    International Nuclear Information System (INIS)

    Anderegg, F.; Stern, R.A.; Skiff, F.; Hammel, B.A.; Tran, M.Q.; Paris, P.J.; Kohler, P.

    1986-01-01

    The E x B rotation and associated collisional ion heating of noble-gas magnetized plasmas are investigated with high resolution by means of laser-induced fluorescence and electrical probes. Plasma rotation results from a radial potential gradient which can be controlled by biasing of the discharge electrodes. The time and space evolution of the potential, the rotation velocity v/sub t//sub h//sub e//sub t//sub a/, and the ion perpendicular temperature indicate that heating is due to the randomization of v/sub t//sub h//sub e//sub t//sub a/ by ion-neutral collisions, and leads to temperature increases as high as a factor of 50 over initial values

  10. Magnetic-field asymmetry of nonlinear thermoelectric and heat transport

    International Nuclear Information System (INIS)

    Hwang, Sun-Yong; Sánchez, David; López, Rosa; Lee, Minchul

    2013-01-01

    Nonlinear transport coefficients do not obey, in general, reciprocity relations. We here discuss the magnetic-field asymmetries that arise in thermoelectric and heat transport of mesoscopic systems. Based on a scattering theory of weakly nonlinear transport, we analyze the leading-order symmetry parameters in terms of the screening potential response to either voltage or temperature shifts. We apply our general results to a quantum Hall antidot system. Interestingly, we find that certain symmetry parameters show a dependence on the measurement configuration. (paper)

  11. Radiofrequency Waves, Heating and Current Drive in Magnetically Confined Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Porkolab, M; Bonoli, P T; Temkin, R J [Plasma Science and Fusion Center, MIT, Cambridge, MA (United States); Pinsker, R I; Prater, R [General Atomics, San Diego, California (United States); Wilson, J R [Princeton Plasma Physics Laboratory, Princeton, NJ (United States)

    2012-09-15

    The need for supplementary heating of magnetically confined plasmas to fusion relevant temperatures ({approx}20 keV) has been recognized from the beginning of modern fusion plasma research. Although in tokamaks the plasmas are formed initially by ohmic heating (P{Omega}{approx}{eta}{sub R}j, where j is the current density and {eta}{sub R} is the resistivity) its effectiveness deteriorates with increasing temperature since the resistivity decreases as T{sub e}{sup -3/2}, and losses due to bremsstrahlung radiation increase as Z{sub eff}{sup 3} T{sub e}{sup 1/2} (where Z{sub eff} is the effective ion charge), and the plasma current cannot be raised to arbitrarily large values because of MHD stability limits. In addition, energy losses due to thermal conduction P{sub loss} are typically anomalously large compared to neoclassical predictions and the dependence on temperature is not well understood. Thus, the simplest form of steady state power balance indicates that losses due to radiation and heat conduction must be balanced by auxiliary heating of some form, P{sub aux}, which may simply be stated as P{sub {Omega}} + P{sub {alpha}} - P{sub loss} P{sub aux} where P{sub {alpha}} is the power input provided by alpha particles, which does not become significant until the temperature exceeds some tens of keV, depending on confinement and density. (author)

  12. Role of Magnetic Reconnection in Heating Astrophysical Plasmas

    Science.gov (United States)

    Hammoud, M. M.; El Eid, M.; Darwish, M.; Dayeh, M. A.

    2017-12-01

    The description of plasma in the context of a fluid model reveals the important phenomenon of magnetic reconnection (MGR). This process is thought to be the cause of particle heating and acceleration in various astrophysical phenomena. Examples are geomagnetic storms, solar flares, or heating the solar corona, which is the focus of the present contribution. The magnetohydrodynamic approach (MHD) provides a basic description of MGR. However, the simulation of this process is rather challenging. Although it is not yet established whether waves or reconnection play the dominant role in heating the solar atmosphere, the present goal is to examine the tremendous increase of the temperature between the solar chromosphere and the corona in a very narrow transition region. Since we are dealing with very-high temperature plasma, the modeling of such heating process seems to require a two-fluid description consisting of ions and electrons. This treatment is an extension of the one-fluid model of resistive MHD that has been recently developed by [Hammoud et al., 2017] using the modern numerical openfoam toolbox. In this work, we outline the two-fluid approach using coronal conditions, show evidence of MGR in the two-fluid description, and investigate the temperature increase as a result of this MGR process.

  13. Micro-magnet arrays for specific single bacterial cell positioning

    Energy Technology Data Exchange (ETDEWEB)

    Pivetal, Jérémy, E-mail: jeremy.piv@netcmail.com [Ecole Centrale de Lyon, CNRS UMR 5005, Laboratoire Ampère, F-69134 Écully (France); Royet, David [Ecole Centrale de Lyon, CNRS UMR 5005, Laboratoire Ampère, F-69134 Écully (France); Ciuta, Georgeta [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Frenea-Robin, Marie [Université de Lyon, Université Lyon 1, CNRS UMR 5005, Laboratoire Ampère, F-69622 Villeurbanne (France); Haddour, Naoufel [Ecole Centrale de Lyon, CNRS UMR 5005, Laboratoire Ampère, F-69134 Écully (France); Dempsey, Nora M. [Univ. Grenoble Alpes, Inst NEEL, F-38042 Grenoble (France); CNRS, Inst NEEL, F-38042 Grenoble (France); Dumas-Bouchiat, Frédéric [Univ Limoges, CNRS, SPCTS UMR 7513, 12 Rue Atlantis, F-87068 Limoges (France); Simonet, Pascal [Ecole Centrale de Lyon, CNRS UMR 5005, Laboratoire Ampère, F-69134 Écully (France)

    2015-04-15

    In various contexts such as pathogen detection or analysis of microbial diversity where cellular heterogeneity must be taken into account, there is a growing need for tools and methods that enable microbiologists to analyze bacterial cells individually. One of the main challenges in the development of new platforms for single cell studies is to perform precise cell positioning, but the ability to specifically target cells is also important in many applications. In this work, we report the development of new strategies to selectively trap single bacterial cells upon large arrays, based on the use of micro-magnets. Escherichia coli bacteria were used to demonstrate magnetically driven bacterial cell organization. In order to provide a flexible approach adaptable to several applications in the field of microbiology, cells were magnetically and specifically labeled using two different strategies, namely immunomagnetic labeling and magnetic in situ hybridization. Results show that centimeter-sized arrays of targeted, isolated bacteria can be successfully created upon the surface of a flat magnetically patterned hard magnetic film. Efforts are now being directed towards the integration of a detection tool to provide a complete micro-system device for a variety of microbiological applications. - Highlights: 1.We report a new approach to selectively micropattern bacterial cells individually upon micro-magnet arrays. 2.Permanent micro-magnets of a size approaching that of bacteria could be fabricated using a Thermo-Magnetic Patterning process. 3.Bacterial cells were labeled using two different magnetic labeling strategies providing flexible approach adaptable to several applications in the field of microbiology.

  14. Monoclonal antibodies specific to heat-treated porcine blood.

    Science.gov (United States)

    Raja Nhari, Raja Mohd Hafidz; Hamid, Muhajir; Rasli, Nurmunirah Mohamad; Omar, Abdul Rahman; El Sheikha, Aly Farag; Mustafa, Shuhaimi

    2016-05-01

    Porcine blood is potentially being utilized in food as a binder, gelling agent, emulsifier or colorant. However, for certain communities, the usage of animal blood in food is strictly prohibited owing to religious concerns and health reasons. This study reports the development of monoclonal antibodies (MAbs) against heat-treated soluble proteins (HSPs) of autoclaved porcine blood; characterization of MAbs against blood, non-blood and plasma from different animal species using qualitative indirect non-competitive enzyme-linked immunosorbent assay (ELISA); and immunoblotting of antigenic components in HSPs of porcine blood. Fifteen MAbs are specific to heat-treated and raw porcine blood and not cross-reacted with other animal blood and non-blood proteins (meat and non-meat). Twelve MAbs are specific to porcine plasma, while three MAbs specific to porcine plasma are cross-reacted with chicken plasma. Immunoblotting revealed antigenic protein bands (∼60, ∼85-100 and ∼250 kDa) in porcine blood and plasma recognized by the MAbs. Selection of MAbs that recognized 60 kDa HSPs of porcine blood and plasma as novel monoclonal antibodies would be useful for detection of porcine plasma in processed food using the immunoassay method. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  15. Heat Flux of a Transferred Arc Driven by a Transverse Magnetic Field

    Directory of Open Access Journals (Sweden)

    Naomi Matsumoto

    2009-01-01

    Full Text Available Theoretical consideration of a magnetically driven arc was performed to elucidate the variation of heat flux with an imposed DC magnetic field. Experiments were conducted to confirm the validity of the theoretical model. The heat flux decreased concomitantly with increased imposed magnetic flux density. Theoretical predictions agreed with experimental results.

  16. Specific heat measurements in KCN:KCL mixed crystals

    International Nuclear Information System (INIS)

    Ghivelder, L.

    1983-01-01

    An adiabatic calorimeter to perform specific heat measurements of small samples (approximatelly 150 mg) was built. The measurements were taken from 6 to 120 K, iN KCN:KCL mixed crystals, in order to observe the evolution of the antiferroelectric phase transition - that occurs at 83 K in KCN pure. From the experimental results the values of the phase transition critical temperature are found, for some particular concentrations of the mixture, and it was detected that this phase transition disappears with only 10% of Cl - . This result is explained in terms of a change of the potential wells in the crystal. (Author) [pt

  17. Specific heat of MgB_2 after irradiation

    OpenAIRE

    Wang, Yuxing; Bouquet, Frederic; Sheikin, Ilya; Toulemonde, Pierre; Revaz, Bernard; Eisterer, Michael; Weber, Harald W.; Hinderer, Joerg; Junod, Alain

    2002-01-01

    We studied the effect of disorder on the superconducting properties of polycrystalline MgB_2 by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with 2 Delta 0 / k_B T_c = 1.3 and 3.9 with nearly equal weights. The scattering introduced by irradiation suppresses T_c and tends to average the two gaps although less than predicted by theory. We also found that by a suitable irradiation process by fast neutr...

  18. Retained Austenite in SAE 52100 Steel Post Magnetic Processing and Heat Treatment

    Energy Technology Data Exchange (ETDEWEB)

    Pappas, Nathaniel R [ORNL; Watkins, Thomas R [ORNL; Cavin, Odis Burl [ORNL; Jaramillo, Roger A [ORNL; Ludtka, Gerard Michael [ORNL

    2007-01-01

    Steel is an iron-carbon alloy that contains up to 2% carbon by weight. Understanding which phases of iron and carbon form as a function of temperature and percent carbon is important in order to process/manufacture steel with desired properties. Austenite is the face center cubic (fcc) phase of iron that exists between 912 and 1394 C. When hot steel is rapidly quenched in a medium (typically oil or water), austenite transforms into martensite. The goal of the study is to determine the effect of applying a magnetic field on the amount of retained austenite present at room temperature after quenching. Samples of SAE 52100 steel were heat treated then subjected to a magnetic field of varying strength and time, while samples of SAE 1045 steel were heat treated then subjected to a magnetic field of varying strength for a fixed time while being tempered. X-ray diffraction was used to collect quantitative data corresponding to the amount of each phase present post processing. The percentage of retained austenite was then calculated using the American Society of Testing and Materials standard for determining the amount of retained austenite for randomly oriented samples and was plotted as a function of magnetic field intensity, magnetic field apply time, and magnetic field wait time after quenching to determine what relationships exist with the amount of retained austenite present. In the SAE 52100 steel samples, stronger field strengths resulted in lower percentages of retained austenite for fixed apply times. The results were inconclusive when applying a fixed magnetic field strength for varying amounts of time. When applying a magnetic field after waiting a specific amount of time after quenching, the analyses indicate that shorter wait times result in less retained austenite. The SAE 1045 results were inconclusive. The samples showed no retained austenite regardless of magnetic field strength, indicating that tempering removed the retained austenite. It is apparent

  19. Detailing Radio Frequency Heating Induced by Coronary Stents: A 7.0 Tesla Magnetic Resonance Study

    Science.gov (United States)

    Santoro, Davide; Winter, Lukas; Müller, Alexander; Vogt, Julia; Renz, Wolfgang; Özerdem, Celal; Grässl, Andreas; Tkachenko, Valeriy; Schulz-Menger, Jeanette; Niendorf, Thoralf

    2012-01-01

    The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR) holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF) power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF) simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR) limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study. PMID:23185498

  20. Detailing radio frequency heating induced by coronary stents: a 7.0 Tesla magnetic resonance study.

    Directory of Open Access Journals (Sweden)

    Davide Santoro

    Full Text Available The sensitivity gain of ultrahigh field Magnetic Resonance (UHF-MR holds the promise to enhance spatial and temporal resolution. Such improvements could be beneficial for cardiovascular MR. However, intracoronary stents used for treatment of coronary artery disease are currently considered to be contra-indications for UHF-MR. The antenna effect induced by a stent together with RF wavelength shortening could increase local radiofrequency (RF power deposition at 7.0 T and bears the potential to induce local heating, which might cause tissue damage. Realizing these constraints, this work examines RF heating effects of stents using electro-magnetic field (EMF simulations and phantoms with properties that mimic myocardium. For this purpose, RF power deposition that exceeds the clinical limits was induced by a dedicated birdcage coil. Fiber optic probes and MR thermometry were applied for temperature monitoring using agarose phantoms containing copper tubes or coronary stents. The results demonstrate an agreement between RF heating induced temperature changes derived from EMF simulations versus MR thermometry. The birdcage coil tailored for RF heating was capable of irradiating power exceeding the specific-absorption rate (SAR limits defined by the IEC guidelines by a factor of three. This setup afforded RF induced temperature changes up to +27 K in a reference phantom. The maximum extra temperature increase, induced by a copper tube or a coronary stent was less than 3 K. The coronary stents examined showed an RF heating behavior similar to a copper tube. Our results suggest that, if IEC guidelines for local/global SAR are followed, the extra RF heating induced in myocardial tissue by stents may not be significant versus the baseline heating induced by the energy deposited by a tailored cardiac transmit RF coil at 7.0 T, and may be smaller if not insignificant than the extra RF heating observed under the circumstances used in this study.

  1. Confinement of ohmically heated plasmas and turbulent heating in high-magnetic field tokamak TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, N; Itoh, S; Kawai, Y; Toi, K; Nakamura, K [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1979-12-01

    TRIAM-1, the tokamak device with high toroidal magnetic field, has been constructed to establish the scaling laws of advanced tokamak devices such as Alcator, and to study the possibility of the turbulent heating as a further economical heating method of the fusion oriented plasmas. The plasma parameters obtained by ohmic heating alone are as follows; central electron temperature T sub(e0) = 640 eV, central ion temperature T sub(i0) = 280 eV and line-average electron density n average sub(e) = 2.2 x 10/sup 14/ cm/sup -3/. The empirical scaling laws are investigated concerning T sub(e0), T sub(i0) and n average sub(e). The turbulent heating has been carried out by applying the high electric field in the toroidal direction to the typical tokamak discharge with T sub(i0) asymptotically equals 200 eV. The efficient ion heating is observed and T sub(i0) attains to about 600 eV.

  2. Heating of polyacrylamide ferrogel by alternating magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Safronov, A.P., E-mail: Safronov@iep.uran.ru [Ural Federal University, Yekaterinburg (Russian Federation); Institute of Elecrophysics, UB RAS, Yekaterinburg (Russian Federation); Samatov, O.M. [Institute of Elecrophysics, UB RAS, Yekaterinburg (Russian Federation); Tyukova, I.S.; Mikhnevich, E.A. [Ural Federal University, Yekaterinburg (Russian Federation); Beketov, I.V. [Ural Federal University, Yekaterinburg (Russian Federation); Institute of Elecrophysics, UB RAS, Yekaterinburg (Russian Federation)

    2016-10-01

    Ferrogel based on polacryamide network with embedded maghemite nanoparticles with mean number average particle diameter 12 nm was synthesized by radical polymerization in water-based ferrofluid. The network structure of ferrogel was characterized by Flory–Rehner theory and it was shown that the embedded particles were substantially larger than the mesh size. It prevented the translational movement of particles in the ferrogel. The immobilization of particles was confirmed by dynamic light scattering. The adhesion of macromolecular chains to the particles was determined by calorimetry using thermochemical cycle. The enthalpy of interfacial adhesion was found several orders of magnitude higher than the energy of dipoles in typically applied magnetic fields. Despite the differenve in the mobility of particles in ferrofluid and ferrogel the comparative study of their heating in alternating magnetic field, however, revealed their close similarity. In both cases it was goverened by superposing of Neel and Brownian relaxation mechanisms. - Highlights: • We synthesized polyacrylamide ferrogel with maghemite nanoparticles. • Nanoparticles are entrapped into gel network. • Polyacrylamide chains are strongly linked to the particles. • Brownian relaxation contributes to heating of ferrogel in alternating field.

  3. Physics responsible for heating efficiency and self-controlled temperature rise of magnetic nanoparticles in magnetic hyperthermia therapy.

    Science.gov (United States)

    Shaterabadi, Zhila; Nabiyouni, Gholamreza; Soleymani, Meysam

    2018-03-01

    Magnetic nanoparticles as heat-generating nanosources in hyperthermia treatment are still faced with many drawbacks for achieving sufficient clinical potential. In this context, increase in heating ability of magnetic nanoparticles in a biologically safe alternating magnetic field and also approach to a precise control on temperature rise are two challenging subjects so that a significant part of researchers' efforts has been devoted to them. Since a deep understanding of Physics concepts of heat generation by magnetic nanoparticles is essential to develop hyperthermia as a cancer treatment with non-adverse side effects, this review focuses on different mechanisms responsible for heat dissipation in a radio frequency magnetic field. Moreover, particular attention is given to ferrite-based nanoparticles because of their suitability in radio frequency magnetic fields. Also, the key role of Curie temperature in suppressing undesired temperature rise is highlighted. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Novel specific heat and magnetoresistance behavior of Tb0.5Ho0.5Mn2Si2

    Science.gov (United States)

    Pandey, Swati; Siruguri, V.; Rawat, R.

    2018-04-01

    In this report, we study temperature dependent heat capacity and electrical resistance of Tb1-xHoxMn2Si2 (x = 0.5). Two successive low temperature magnetic transitions T1 (˜15 K) and T2 (˜25 K) are observed from both measurements. Anomalous rise in heat capacity at low temperatures is ascribed to the nuclear Schottky effect. Sommerfeld coefficient (γ), Debye temperature (θD) and density of states at Fermi level N(EF) is calculated from the zero field specific heat data. We observe 4f contribution to heat capacity from T1 to 100K, which is attributed to crystal field effect. In the electrical transport study, application of the magnetic field shows a substantial change around the ordering temperature of rare earth moment resulting in large positive magnetoresistance of about 20% with field change of 6T.

  5. Specific heat studies of lanthanum and yttrium sesquicarbides

    International Nuclear Information System (INIS)

    Cort, B.; Stewart, G.R.; Giorgi, A.L.

    1984-01-01

    The specific heats of the sesquicarbides LaC/sub 1.35/ and La/sub 0.9/Th/sub 0.1/C/sub 1.6/ (prepared by arc melting) and YC/sub 1.35/ (prepared by a high-pressure technique) have been measured for the first time. No bulk specific heat anomaly appears in either lanthanum compounds, even though (1) inductively measured superconducting transition temperatures are respectively high (11.0 K for LaC/sub 1.35/ and 12.7 K for La/sub 0.9/Th/sub 0.1/C/sub 1.6/) and (2) YC/sub 1.35/ is a bulk superconductor with a T/sub c/ = 10.5 K and Y/sub 0.7/Th/sub 0.3/C/sub 1.58/ (also prepared by high pressure) was previously reported to be a bulk superconductor with a T/sub c/ = 17.1 K. The apparent correlation with preparation technique is discussed

  6. Specific heat of nano-ferrites modified composites

    Directory of Open Access Journals (Sweden)

    Muntenita Cristian

    2017-01-01

    Full Text Available The specific heat of nano-ferrites modified composites was studied using differential scanning calorimeter (DSC method in the temperature range of 30 to 150°C. Initially, nano-ferrites were introduced in epoxy systems in order to improve the electromagnetic properties of formed materials. Together with the changes in electromagnetic properties some modifications occur regarding thermal and mechanical properties. The materials were formed by placing 5g or 10g of ferrite into 250g polymer matrix leading to a very low weight ratio of modifying agent. At so low ratios the effect of ferrite presence should be insignificant according to mixing rule. Anyway there is possible to appear some chelation reaction with effects on thermal properties of materials. Three types of epoxy resins had been used as matrix and barium ferrite and strontium ferrite as modifying agents. The thermal analysis was developed on two heatingcooling cycles and the specific heat was evaluated for each segment of the cycle analysis.

  7. The dynamics of magnetic nanoparticles exposed to non-heating alternating magnetic field in biochemical applications: theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, Yuri I., E-mail: nano@tsutmb.ru [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Gribanovsky, Sergey L.; Golovin, Dmitry Y.; Zhigachev, Alexander O. [G.R. Derzhavin Tambov State University, Nanocenter (Russian Federation); Klyachko, Natalia L.; Majouga, Alexander G. [Lomonosov Moscow State University, Chemistry Department (Russian Federation); Sokolsky, Marina [University of North Carolina, Center for Nanotechnology in Drug Delivery, UNC Eshelman School of Pharmacy (United States); Kabanov, Alexander V. [Lomonosov Moscow State University, Chemistry Department (Russian Federation)

    2017-02-15

    In the past decade, magneto-nanomechanical approach to biochemical systems stimulation has been studied intensively. This method involves macromolecule structure local deformation via mechanical actuation of functionalized magnetic nanoparticles (f-MNPs) by non-heating low frequency (LF) alternating magnetic field (AMF). Specificity at cellular or molecular level and spatial locality in nanometer scale are its key advantages as compared to magnetic fluid hyperthermia. However, current experimental studies have weak theoretical basis. Several models of magneto-nanomechanical actuation of macromolecules and cells in non-heating uniform LF AMF are presented in the article. Single core-shell spherical, rod-like, and Janus MNPs, as well as dimers consisting of two f-MNPs with macromolecules immobilized on their surfaces are considered. AMF-induced rotational oscillations of MNPs can affect properties and functioning of macromolecules or cellular membranes attached to them via periodic deformations in nanometer scale. This could be widely used in therapy, in particular for targeted drug delivery, controlled drug release, and cancer cell killing. An aggregate composed of MNPs can affect associated macromolecules by force up to several hundreds of piconewton in the case of MNPs of tens of nanometers in diameter and LF AMF below 1 T. AMF parameters and MNP design requirements for effective in vitro and in vivo magneto-nanomechanical treatment are presented.

  8. The dynamics of magnetic nanoparticles exposed to non-heating alternating magnetic field in biochemical applications: theoretical study

    International Nuclear Information System (INIS)

    Golovin, Yuri I.; Gribanovsky, Sergey L.; Golovin, Dmitry Y.; Zhigachev, Alexander O.; Klyachko, Natalia L.; Majouga, Alexander G.; Sokolsky, Marina; Kabanov, Alexander V.

    2017-01-01

    In the past decade, magneto-nanomechanical approach to biochemical systems stimulation has been studied intensively. This method involves macromolecule structure local deformation via mechanical actuation of functionalized magnetic nanoparticles (f-MNPs) by non-heating low frequency (LF) alternating magnetic field (AMF). Specificity at cellular or molecular level and spatial locality in nanometer scale are its key advantages as compared to magnetic fluid hyperthermia. However, current experimental studies have weak theoretical basis. Several models of magneto-nanomechanical actuation of macromolecules and cells in non-heating uniform LF AMF are presented in the article. Single core-shell spherical, rod-like, and Janus MNPs, as well as dimers consisting of two f-MNPs with macromolecules immobilized on their surfaces are considered. AMF-induced rotational oscillations of MNPs can affect properties and functioning of macromolecules or cellular membranes attached to them via periodic deformations in nanometer scale. This could be widely used in therapy, in particular for targeted drug delivery, controlled drug release, and cancer cell killing. An aggregate composed of MNPs can affect associated macromolecules by force up to several hundreds of piconewton in the case of MNPs of tens of nanometers in diameter and LF AMF below 1 T. AMF parameters and MNP design requirements for effective in vitro and in vivo magneto-nanomechanical treatment are presented.

  9. The dynamics of magnetic nanoparticles exposed to non-heating alternating magnetic field in biochemical applications: theoretical study

    Science.gov (United States)

    Golovin, Yuri I.; Gribanovsky, Sergey L.; Golovin, Dmitry Y.; Zhigachev, Alexander O.; Klyachko, Natalia L.; Majouga, Alexander G.; Sokolsky, Marina; Kabanov, Alexander V.

    2017-02-01

    In the past decade, magneto-nanomechanical approach to biochemical systems stimulation has been studied intensively. This method involves macromolecule structure local deformation via mechanical actuation of functionalized magnetic nanoparticles (f-MNPs) by non-heating low frequency (LF) alternating magnetic field (AMF). Specificity at cellular or molecular level and spatial locality in nanometer scale are its key advantages as compared to magnetic fluid hyperthermia. However, current experimental studies have weak theoretical basis. Several models of magneto-nanomechanical actuation of macromolecules and cells in non-heating uniform LF AMF are presented in the article. Single core-shell spherical, rod-like, and Janus MNPs, as well as dimers consisting of two f-MNPs with macromolecules immobilized on their surfaces are considered. AMF-induced rotational oscillations of MNPs can affect properties and functioning of macromolecules or cellular membranes attached to them via periodic deformations in nanometer scale. This could be widely used in therapy, in particular for targeted drug delivery, controlled drug release, and cancer cell killing. An aggregate composed of MNPs can affect associated macromolecules by force up to several hundreds of piconewton in the case of MNPs of tens of nanometers in diameter and LF AMF below 1 T. AMF parameters and MNP design requirements for effective in vitro and in vivo magneto-nanomechanical treatment are presented.

  10. Hysteresis losses and specific absorption rate measurements in magnetic nanoparticles for hyperthermia applications.

    Science.gov (United States)

    Coïsson, Marco; Barrera, Gabriele; Celegato, Federica; Martino, Luca; Kane, Shashank N; Raghuvanshi, Saroj; Vinai, Franco; Tiberto, Paola

    2017-06-01

    Magnetic hysteresis loops areas and hyperthermia on magnetic nanoparticles have been studied with the aim of providing reliable and reproducible methods of measuring the specific absorption rate (SAR). The SAR of Fe 3 O 4 nanoparticles with two different mean sizes, and Ni 1-x Zn x Fe 2 O 4 ferrites with 0 ≤ x ≤ 0.8 has been measured with three approaches: static hysteresis loops areas, dynamic hysteresis loops areas and hyperthermia of a water solution. For dynamic loops and thermometric measurements, specific experimental setups have been developed, that operate at comparable frequencies (≈ 69kHz and ≈ 100kHz respectively) and rf magnetic field peak values (up to 100mT). The hyperthermia setup has been fully modelled to provide a direct measurement of the SAR of the magnetic nanoparticles by taking into account the heat exchange with the surrounding environment in non-adiabatic conditions and the parasitic heating of the water due to ionic currents. Dynamic hysteresis loops are shown to provide an accurate determination of the SAR except for superparamagnetic samples, where the boundary with a blocked regime could be crossed in dynamic conditions. Static hysteresis loops consistently underestimate the specific absorption rate but can be used to select the most promising samples. A means of reliably measure SAR of magnetic nanoparticles by different approaches for hyperthermia applications is presented and its validity discussed by comparing different methods. This work fits within the general subject of metrological traceability in medicine with a specific focus on magnetic hyperthermia. This article is part of a Special Issue entitled "Recent Advances in Bionanomaterials" Guest Editor: Dr. Marie-Louise Saboungi and Dr. Samuel D. Bader. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. An experimental study of magnetic-field and temperature dependence on magnetic fluid’s heating power

    International Nuclear Information System (INIS)

    Beković, Miloš; Trlep, Mladen; Jesenik, Marko; Goričan, Viktor; Hamler, Anton

    2013-01-01

    This paper firstly presents a measurement system for determining the magnetic properties of magnetic fluids, based on three pickup coils. The accuracy of the system was tested on known samples and then used for the characterization of magnetic losses (heating power P) on the magnetic fluid sample using two different methods. The first method is based on determining the hysteresis loop area and the second on determining the complex susceptibility; and showed that both methods are equivalent. The aim of this paper was to identify the heating power of the liquid at a known value for the magnetic field, and the arbitrary temperature. Thus, we explored the actual reduction in the heating power due to the heating of the sample, which cannot be achieved without the temperature regulated heat bath using established calorimetric methods. -- Highlights: ► A new measurement system was tested with numerous samples, and results were promising. ► Magnetic fluid heating power was determined using a system of J-compensated coil. ► Complex susceptibility method results equal losses as hysteresis loops approach. ► Temperature dependent heating power was explored without the heath-bath . ► For larger magnetic fields a linear H dependence of heating power is revealed

  12. Performance evaluation of citric ion-stabilized magnetic fluid heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Jeyadevan, B. [Graduate School of Environmental Studies, Department of Geoscience and Technology, Tohoku University, Aramaki, Aoba 01, Aoba-ku, Sendai 980-7589 (Japan)]. E-mail: jeya@mail.kankyo.tohoku.ac.jp; Koganezawa, H. [Graduate School of Environmental Studies, Department of Geoscience and Technology, Tohoku University, Aramaki, Aoba 01, Aoba-ku, Sendai 980-7589 (Japan); Nakatsuka, K. [Graduate School of Environmental Studies, Department of Geoscience and Technology, Tohoku University, Aramaki, Aoba 01, Aoba-ku, Sendai 980-7589 (Japan)

    2005-03-15

    The performance of heat pipe (HP) using citric ion-stabilized magnetic fluid (CMF) as working fluid (WF) was evaluated. The heat transferred was influenced by the application of magnetic field and was enhanced by a maximum of 30% compared to the field-free case. Furthermore, under the optimum magnetic field configuration, the heat transferred by CMF HP was 10% higher than that with water as WF.

  13. Low-temperature specific heat measurements on the NdCoxFe1-xO3 system

    International Nuclear Information System (INIS)

    Bartolome, F.; Kuz'min, M.D.; Bartolome, J.; Blasco, J.; Garcia, J.

    1995-01-01

    Low-temperature specific heat measurements have been carried out on the NdCo x Fe 1-x O 3 perovskite system (x=0, 0.25, 0.5, 0.9, 1). Magnetic ordering of Nd 3+ ions have been observed in NdCoO 3 (at 1.20 K) and NdFeO 3 (at 1.05 K). The studied dilutions, unlike the pure Fe or Co compounds, do not show a magnetic order of the Nd ions due to the stronger molecular field caused by decompensation of the internal field upon the introduction of the (Co 3+ ) magnetic vacancies in the antiferromagnetically ordered Fe subsystem. The specific heat curve of the system at x=0.9 resembles spin-glass behaviour. ((orig.))

  14. Enhancement in heat transfer of a ferrofluid in a differentially heated square cavity through the use of permanent magnets

    Science.gov (United States)

    Joubert, J. C.; Sharifpur, M.; Solomon, A. Brusly; Meyer, J. P.

    2017-12-01

    The natural convection heat transfer of a magnetic nanofluid in a differentially heated cavity is investigated with and without an applied external magnetic field. The effects of volume fraction, magnetic field configuration, and magnetic field strength are investigated. Spherical Fe2O3 nanoparticles with a diameter of 15-20 nm are used in the nanofluids. Volume fractions ranging between 0.05% and 0.3% are tested for the case with no magnetic field, while only a volume fraction of 0.1% was tested in an externally applied magnetic field. The experiments were conducted for a range of Rayleigh numbers in 1.7 × 108 < Ra < 4.2 × 108. The viscosity of the nanofluid was determined experimentally. An empirical correlation for the viscosity was determined, and the stability of various nanofluids was investigated. Using heat transfer data obtained from the cavity, the average heat transfer coefficient and average Nusselt number for the nanofluids are determined. It was found that a volume fraction of 0.1% showed a maximum increase of 5.63% to the Nu at the maximum Ra. For the magnetic field study, it was found that the best-performing magnetic field enhanced the heat transfer behaviour by an additional 2.81% in Nu at Ra = 3.8 × 108.

  15. Digital lock-in detection of site-specific magnetism in magnetic materials

    Science.gov (United States)

    Haskel, Daniel [Naperville, IL; Lang, Jonathan C [Naperville, IL; Srajer, George [Oak Park, IL

    2008-07-22

    The polarization and diffraction characteristics of x-rays incident upon a magnetic material are manipulated to provide a desired magnetic sensitivity in the material. The contrast in diffracted intensity of opposite helicities of circularly polarized x-rays is measured to permit separation of magnetic signals by element type and by atomic environment. This allows for the direct probing of magnetic signals from elements of the same species in nonequivalent atomic environments to better understand the behavior and characteristics of permanent magnetic materials. By using known crystallographic information together with manipulation of the polarization of x-rays having energies tuned near element-specific electronic excitations and by detecting and comparing the incident and diffracted photons at the same frequency, more accurate magnetic measurements can be made over shorter observation periods.

  16. Use of miniature magnetic sensors for real-time control of the induction heating process

    Science.gov (United States)

    Bentley, Anthony E.; Kelley, John Bruce; Zutavern, Fred J.

    2002-01-01

    A method of monitoring the process of induction heating a workpiece. A miniature magnetic sensor located near the outer surface of the workpiece measures changes in the surface magnetic field caused by changes in the magnetic properties of the workpiece as it heats up during induction heating (or cools down during quenching). A passive miniature magnetic sensor detects a distinct magnetic spike that appears when the saturation field, B.sub.sat, of the workpiece has been exceeded. This distinct magnetic spike disappears when the workpiece's surface temperature exceeds its Curie temperature, due to the sudden decrease in its magnetic permeability. Alternatively, an active magnetic sensor can also be used to measure changes in the resonance response of the monitor coil when the excitation coil is linearly swept over 0-10 MHz, due to changes in the magnetic permeability and electrical resistivity of the workpiece as its temperature increases (or decreases).

  17. Heat transfer in flow past a continuously moving semi-infinite flat plate in transverse magnetic field with heat flux

    Digital Repository Service at National Institute of Oceanography (India)

    Murty, T.V.R.

    Thermal boundary layer on a continuously moving semi-infinite flat plate in the presence of transverse magnetic field with heat flux has been examined. Similarity solutions have been derived and the resulting equations are integrated numerically...

  18. Magnetic-susceptibility and heat-capacity measurements on PrRhSb

    International Nuclear Information System (INIS)

    Malik, S.K.; Takeya, H.; Gschneidner, K.A. Jr.

    1994-01-01

    Magnetic-susceptibility (ac and dc) and heat-capacity measurements have been carried out on the compound PrRhSb. These measurements reveal two magnetic transitions in this compound---one at about 18 K and the other around 6 K. In the dc susceptibility the 18-K transition is evident as the temperature below which a magnetic correlation sets in and the susceptibility is found to be field dependent. The lower transition manifests as a peak in the susceptibility of zero-field-cooled samples which were measured in low applied fields. The electronic-specific-heat coefficient, γ, is found to be 33 mJ/mol K 2 between 40 and 70 K after correcting for the lattice contribution taken to be the same as in its La analog. The γ value is fairly large for a Pr compound and may be indicative of moderately heavy quasiparticles. A Kondo-type interaction of the Pr 4f electrons with the conduction electrons may be responsible for high-magnetic-ordering temperatures and the moderately large γ value in this compound

  19. Specific heat of MgB{sub 2} after irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yuxing [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland); Bouquet, Frederic [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland); Sheikin, Ilya [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland); Toulemonde, Pierre [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland); Revaz, Bernard [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland); Eisterer, Michael [Atominstitut der Oesterreichischen Universitaeten, A-1020 Vienna (Austria); Weber, Harald W [Atominstitut der Oesterreichischen Universitaeten, A-1020 Vienna (Austria); Hinderer, Joerg [GHMFL, Max-Planck Institute Grenoble, BP 166, F-38042, Grenoble (France); Junod, Alain [Universite de Geneve, Departement de physique de la matiere condensee, 24 quai Ernest-Ansermet, CH-1211 Geneva (Switzerland)

    2003-02-19

    We studied the effect of disorder on the superconducting properties of polycrystalline MgB{sub 2} by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with 2{delta}{sub 0}/k{sub B}T{sub c}=1.3 and 3.9 with nearly equal weights. The scattering introduced by irradiation suppresses T{sub c} and tends to average the two gaps although less than predicted by theory. We also found that by a suitable irradiation process by fast neutrons, a substantial bulk increase of dH{sub c2}/dT at T{sub c} can be obtained without sacrificing more than a few degrees in T{sub c}. The upper critical field of the sample after irradiation exceeds 28 T at T{yields}0.

  20. Specific heat of MgB2 after irradiation

    International Nuclear Information System (INIS)

    Wang Yuxing; Bouquet, Frederic; Sheikin, Ilya; Toulemonde, Pierre; Revaz, Bernard; Eisterer, Michael; Weber, Harald W; Hinderer, Joerg; Junod, Alain

    2003-01-01

    We studied the effect of disorder on the superconducting properties of polycrystalline MgB 2 by specific-heat measurements. In the pristine state, these measurements give a bulk confirmation of the presence of two superconducting gaps with 2Δ 0 /k B T c =1.3 and 3.9 with nearly equal weights. The scattering introduced by irradiation suppresses T c and tends to average the two gaps although less than predicted by theory. We also found that by a suitable irradiation process by fast neutrons, a substantial bulk increase of dH c2 /dT at T c can be obtained without sacrificing more than a few degrees in T c . The upper critical field of the sample after irradiation exceeds 28 T at T→0

  1. Unsteady Flow in a Supersonic Turbine with Variable Specific Heats

    Science.gov (United States)

    Dorney, Daniel J.; Griffin, Lisa W.; Huber, Frank; Sondak, Douglas L.; Turner, James (Technical Monitor)

    2001-01-01

    Modern high-work turbines can be compact, transonic, supersonic, counter-rotating, or use a dense drive gas. The vast majority of modern rocket turbine designs fall into these Categories. These turbines usually have large temperature variations across a given stage, and are characterized by large amounts of flow unsteadiness. The flow unsteadiness can have a major impact on the turbine performance and durability. For example, the Space Transportation Main Engine (STME) fuel turbine, a high work, transonic design, was found to have an unsteady inter-row shock which reduced efficiency by 2 points and increased dynamic loading by 24 percent. The Revolutionary Reusable Technology Turbopump (RRTT), which uses full flow oxygen for its drive gas, was found to shed vortices with such energy as to raise serious blade durability concerns. In both cases, the sources of the problems were uncovered (before turbopump testing) with the application of validated, unsteady computational fluid dynamics (CFD) to the designs. In the case of the RRTT and the Alternate Turbopump Development (ATD) turbines, the unsteady CFD codes have been used not just to identify problems, but to guide designs which mitigate problems due to unsteadiness. Using unsteady flow analyses as a part of the design process has led to turbine designs with higher performance (which affects temperature and mass flow rate) and fewer dynamics problems. One of the many assumptions made during the design and analysis of supersonic turbine stages is that the values of the specific heats are constant. In some analyses the value is based on an average of the expected upstream and downstream temperatures. In stages where the temperature can vary by 300 to 500 K, however, the assumption of constant fluid properties may lead to erroneous performance and durability predictions. In this study the suitability of assuming constant specific heats has been investigated by performing three-dimensional unsteady Navier

  2. Compressional heating in magnetized disks neighborhood: from the galactic center to micro-quasars

    International Nuclear Information System (INIS)

    Belmont, Renaud

    2005-01-01

    Faint, magnetized and energetic plasmas are very common media in Astrophysics. This thesis is dedicated to two specific cases characterized by a thin disk geometry: the Galactic center and the corona of micro-quasars. In both cases, observations show evidence for a faint and very hot plasma (at 100 million and 1 billion degrees) whose origin is unknown; some clues seem also to indicate a strong, large scale bipolar magnetic field. At the Galactic Center, the gas temperature is such that, if it were collisional and mostly composed by hydrogen, it would escape quickly, so that the power required to sustain the related energy losses would be huge. We however show that the specific conditions of this region can lead to form a helium plasma that is confined by the Galactic potential. In this favorable situation, we study a possible heating mechanism based on the high viscosity of the hot plasma and friction with cold molecular clouds flowing in this region. The corona of micro-quasars is a very similar issue but it is probably weakly collisional. In this regime we study a heating by magnetic pumping, by which the resonance between the periodic motion of some coronal ions and the periodic excitation by an instability in the disc itself can energize the corona. We show that this mechanism is inefficient to explain the hot temperature. (author) [fr

  3. Sex specific effects of heat induced hormesis in Hsf-deficient Drosophila melanogaster

    DEFF Research Database (Denmark)

    Sørensen, J G; Kristensen, Torsten Nygård; Kristensen, K V

    2007-01-01

    In insects mild heat stress early in life has been reported to increase life span and heat resistance later in life, a phenomenon termed hormesis. Here, we test if the induction of the heat shock response by mild heat stress is mediating hormesis in longevity and heat resistance at older age...... line, seemingly mediated by the production of heat shock proteins (Hsps). The results indicate that heat inducible Hsps are important for heat induced hormesis in longevity and heat stress resistance. However, the results also suggest that other processes are involved and that different mechanisms...... might have marked sex specific impact...

  4. Theranostic multimodal potential of magnetic nanoparticles actuated by non-heating low frequency magnetic field in the new-generation nanomedicine

    Energy Technology Data Exchange (ETDEWEB)

    Golovin, Yuri I., E-mail: nano@tsutmb.ru; Klyachko, Natalia L.; Majouga, Alexander G. [M.V. Lomonosov Moscow State University, Chemistry Faculty (Russian Federation); Sokolsky, Marina [University of North Carolina at Chapel Hill, Center for Nanotechnology in Drug Delivery, UNC Eshelman School of Pharmacy (United States); Kabanov, Alexander V. [M.V. Lomonosov Moscow State University, Chemistry Faculty (Russian Federation)

    2017-02-15

    The scope of this review involves one of the most promising branches of new-generation biomedicine, namely magnetic nanotheranostics using remote control of functionalized magnetic nanoparticles (f-MNPs) by means of alternating magnetic fields (AMFs). The review is mainly focused on new approach which utilizes non-heating low frequency magnetic fields (LFMFs) for nanomechanical actuation of f-MNPs. This approach is compared to such traditional ones as magnetic resonance imaging (MRI) and radio-frequency (RF) magnetic hyperthermia (MH) which utilize high frequency heating AMF. The innovative principles and specific models of non-thermal magnetomechanical actuation of biostructures by MNP rotational oscillations in LFMF are described. The discussed strategy allows biodistribution monitoring in situ, delivering drugs to target tissues and releasing them with controlled rate, controlling biocatalytic reaction kinetics, inducing malignant cell apoptosis, and more. Optimization of both LFMF and f-MNP parameters may lead to dramatic improvement of treatment efficiency, locality, and selectivity on molecular or cellular levels and allow implementing both drug and drugless, i.e., pure nanomechanical therapy, in particular cancer therapy. The optimal parameters within this approach differ significantly from those used in MH or MRI because of the principal difference in the f-MNP actuation modes. It is shown that specifically designed high gradient, steady magnetic field enables diagnostic and therapeutic LFMF impact localization in the deep tissues within the area ranging from a millimeter to a few centimeters and 3D scanning of affected region, if necessary.

  5. Theranostic multimodal potential of magnetic nanoparticles actuated by non-heating low frequency magnetic field in the new-generation nanomedicine

    Science.gov (United States)

    Golovin, Yuri I.; Klyachko, Natalia L.; Majouga, Alexander G.; Sokolsky, Marina; Kabanov, Alexander V.

    2017-02-01

    The scope of this review involves one of the most promising branches of new-generation biomedicine, namely magnetic nanotheranostics using remote control of functionalized magnetic nanoparticles (f-MNPs) by means of alternating magnetic fields (AMFs). The review is mainly focused on new approach which utilizes non-heating low frequency magnetic fields (LFMFs) for nanomechanical actuation of f-MNPs. This approach is compared to such traditional ones as magnetic resonance imaging (MRI) and radio-frequency (RF) magnetic hyperthermia (MH) which utilize high frequency heating AMF. The innovative principles and specific models of non-thermal magnetomechanical actuation of biostructures by MNP rotational oscillations in LFMF are described. The discussed strategy allows biodistribution monitoring in situ, delivering drugs to target tissues and releasing them with controlled rate, controlling biocatalytic reaction kinetics, inducing malignant cell apoptosis, and more. Optimization of both LFMF and f-MNP parameters may lead to dramatic improvement of treatment efficiency, locality, and selectivity on molecular or cellular levels and allow implementing both drug and drugless, i.e., pure nanomechanical therapy, in particular cancer therapy. The optimal parameters within this approach differ significantly from those used in MH or MRI because of the principal difference in the f-MNP actuation modes. It is shown that specifically designed high gradient, steady magnetic field enables diagnostic and therapeutic LFMF impact localization in the deep tissues within the area ranging from a millimeter to a few centimeters and 3D scanning of affected region, if necessary.

  6. Introduction to wave heating and current drive in magnetized plasmas

    International Nuclear Information System (INIS)

    Pinsker, R. I.

    2001-01-01

    The development of high-power wave heating and current drive in magnetized plasmas in the last 40 years is a major ongoing success story in plasma science. A hallmark of this area of research has been the detailed quantitative comparison of theory and experiment; the good agreement consistently found is indicative of the robustness and the predictive power of the underlying theory. This tutorial paper is a brief overview of the fundamental concepts and applications of this branch of plasma science. Most of the high-power applications have been in three frequency regimes: the ion cyclotron range of frequencies (ICRF), the lower hybrid range of frequencies (LHRF), and the electron cyclotron range of frequencies (ECRF). The basic physics of wave propagation and damping in these regimes is briefly discussed. Some of the coupling structures (antennas) used to excite the waves at the plasma boundary are described, and the high-power systems used to generate the wave energy are touched on. Representative examples of the remarkably wide range of applications of high-power wave heating and current drive in high-temperature fusion plasmas will be discussed

  7. Development of supersonic plasma flows by use of a magnetic nozzle and an ICRF heating

    Energy Technology Data Exchange (ETDEWEB)

    Inutake, M.; Ando, A.; Hattori, K.; Tobari, H.; Hosokawa, Y.; Sato, R.; Hatanaka, M.; Harata, K. [Tohoku Univ., Dept. of Electrical Engineering, Sendai (Japan)

    2004-07-01

    A high-beta, supersonic plasma flow plays a crucial role in MHD phenomena in space and fusion plasmas. There are a few experimental researches on production and control of a fast flowing plasma in spite of a growing significance in the magnetized-plasma flow dynamics. A magneto-plasma-dynamic arc-jet (MPDA) is one of promising devices to produce a supersonic plasma flow and has been utilized as an electric propulsion device with a higher specific impulse and a relatively larger thrust. We have improved the performance of an MPDA to produce a quasi-steady plasma flow with a transonic and supersonic Mach number in a highly-ionized state. There are two methods in order to control an ion-acoustic Mach number of the plasma flow exhausted from an MPDA: one is to use a magnetic Laval nozzle to convert a thermal energy to a flow energy and the other is a combined system of an ion heating and a divergent magnetic nozzle. The former is an analogous method to a compressible air flow and the latter is the method proposed in an advanced thruster for a manned interplanetary space mission. We have clarified the plasma flow characteristics in various shapes of a magnetic field configuration. It was demonstrated that the Mach number of the plasma flow could increase up to almost 3 in a divergent magnetic nozzle field. This paper reports recent results on the flow field improvements: one is on a magnetic-Laval-nozzle effects observed at the muzzle region of the MPDA, and the other is on ICRF (ion-cyclotron-range of frequency) heating of a supersonic plasma by use of a helical antenna. (authors)

  8. Method to reduce non-specific tissue heating of small animals in solenoid coils.

    Science.gov (United States)

    Kumar, Ananda; Attaluri, Anilchandra; Mallipudi, Rajiv; Cornejo, Christine; Bordelon, David; Armour, Michael; Morua, Katherine; Deweese, Theodore L; Ivkov, Robert

    2013-01-01

    Solenoid coils that generate time-varying or alternating magnetic fields (AMFs) are used in biomedical devices for research, imaging and therapy. Interactions of AMF and tissue produce eddy currents that deposit power within tissue, thus limiting effectiveness and safety. We aim to develop methods that minimise excess heating of mice exposed to AMFs for cancer therapy experiments. Numerical and experimental data were obtained to characterise thermal management properties of water using a continuous, custom water jacket in a four-turn simple solenoid. Theoretical data were obtained with method-of-moments (MoM) numerical field calculations and finite element method (FEM) thermal simulations. Experimental data were obtained from gel phantoms and mice exposed to AMFs having amplitude >50 kA/m and frequency of 160 kHz. Water has a high specific heat and thermal conductivity, is diamagnetic, polar, and nearly transparent to magnetic fields. We report at least a two-fold reduction of temperature increase from gel phantom and animal models when a continuous layer of circulating water was placed between the sample and solenoid, compared with no water. Thermal simulations indicate the superior efficiency in thermal management by the developed continuous single chamber cooling system over a double chamber non-continuous system. Further reductions of heating were obtained by regulating water temperature and flow for active cooling. These results demonstrate the potential value of a contiguous layer of circulating water to permit sustained exposure to high intensity alternating magnetic fields at this frequency for research using small animal models exposed to AMFs.

  9. Performance characteristics and parametric optimization of an irreversible magnetic Ericsson heat-pump

    International Nuclear Information System (INIS)

    Wei Fang; Lin Guoxing; Chen Jincan; Brueck, Ekkes

    2011-01-01

    Taking into account the finite-rate heat transfer in the heat-transfer processes, heat leak between the two external heat reservoirs, regenerative loss, regeneration time, and internal irreversibility due to dissipation of the cycle working substance, an irreversible magnetic Ericsson heat-pump cycle is presented. On the basis of the thermodynamic properties of magnetic materials, the performance characteristics of the irreversible magnetic Ericsson heat-pump are investigated and the relationship between the optimal heating load and the coefficient of performance (COP) is derived. Moreover, the maximum heating load and the corresponding COP as well as the maximum COP and the corresponding heating load are obtained. Furthermore, the other optimal performance characteristics are discussed in detail. The results obtained here may provide some new information for the optimal parameter design and the development of real magnetic Ericsson heat-pumps. -- Research Highlights: →The effects of multi-irreversibilities on the performance of a magnetic heat-pump are revealed. →Mathematical expressions of the heating load and the COP are derived and the optimal performance and operating parameters are analyzed and discussed. →Several important performance bounds are determined.

  10. Multivoxel proton magnetic resonance spectroscopy in heat stroke

    International Nuclear Information System (INIS)

    Li, J.; Zhang, X.Y.; Wang, B.; Zou, Z.M.; Li, H.F.; Wang, P.Y.; Xia, J.K.

    2015-01-01

    Aim: To assess the role of proton MR spectroscopy (MRS) in the detection of changes in metabolite levels of the cerebellum after heat stroke (HS). Materials and methods: The study group consisted of eight patients after HS, with a Glasgow Coma Scale (GCS) score of 3–9. The MR studies were performed with a 1.5 T system. MR spectra were recorded from a normal-appearing cerebellum region. Spectra from patients were compared with a control group including seven age-matched healthy volunteers recorded with the same techniques. Metabolites ratios including N-acetyl aspartate/creatine (NAA/Cr), N-acetyl aspartate/creatine2 (NAA/Cr2), choline/creatine (Cho/Cr), choline/creatine2 (Cho/Cr2), and N-acetyl aspartate/choline (NAA/Cho) were calculated and the differences between the two groups were evaluated using the Mann–Whitney U-test. Pearson correlation analysis was used to analyse the relationship between NAA/Cr ratios and GCS scores for eight patients after HS. Results: In the cerebellum of the patients after HS, NAA/Cr ratios were found to be significantly decreased compared to normal controls (p = 0.004) and Cho/Cr ratios were found to be decreased compared to normal controls (p = 0.032). Significant positive correlation was found between NAA/Cr ratios and GCS scores for eight patients after HS (r = 0.748, p = 0.033). Conclusions: Metabolite abnormalities were seen in normal-appearing cerebellum structures in patients after HS. Proton MRS is a useful tool for evaluating major changes in metabolite levels of the cerebellum after HS and the severity of the disease can be effectively evaluated by NAA/Cr ratios. - Highlights: • Proton magnetic resonance spectroscopy offers important information in patients with heat stroke. • Significantly different NAA/Cr ratios were found between heat stroke and controls. • The severity of heat stroke can be effectively evaluated by NAA/Cr ratios

  11. Closed loop control of the induction heating process using miniature magnetic sensors

    Science.gov (United States)

    Bentley, Anthony E.; Kelley, John Bruce; Zutavern, Fred J.

    2003-05-20

    A method and system for providing real-time, closed-loop control of the induction hardening process. A miniature magnetic sensor located near the outer surface of the workpiece measures changes in the surface magnetic field caused by changes in the magnetic properties of the workpiece as it heats up during induction heating (or cools down during quenching). A passive miniature magnetic sensor detects a distinct magnetic spike that appears when the saturation field, B.sub.sat, of the workpiece has been exceeded. This distinct magnetic spike disappears when the workpiece's surface temperature exceeds its Curie temperature, due to the sudden decrease in its magnetic permeability. Alternatively, an active magnetic sensor can measure changes in the resonance response of the monitor coil when the excitation coil is linearly swept over 0-10 MHz, due to changes in the magnetic permeability and electrical resistivity of the workpiece as its temperature increases (or decreases).

  12. System and method for heating ferrite magnet motors for low temperatures

    Science.gov (United States)

    Reddy, Patel Bhageerath; El-Refaie, Ayman Mohamed Fawzi; Huh, Kum-Kang

    2017-07-04

    A system and method for heating ferrite permanent magnets in an electrical machine is disclosed. The permanent magnet machine includes a stator assembly and a rotor assembly, with a plurality of ferrite permanent magnets disposed within the stator assembly or the rotor assembly to generate a magnetic field that interacts with a stator magnetic field to produce a torque. A controller of the electrical machine is programmed to cause a primary field current to be applied to the stator windings to generate the stator magnetic field, so as to cause the rotor assembly to rotate relative to the stator assembly. The controller is further programmed to cause a secondary current to be applied to the stator windings to selectively generate a secondary magnetic field, the secondary magnetic field inducing eddy currents in at least one of the stator assembly and the rotor assembly to heat the ferrite permanent magnets.

  13. System and method for heating ferrite magnet motors for low temperatures

    Science.gov (United States)

    Reddy, Patel Bhageerath; El-Refaie, Ayman Mohamed Fawzi; Huh, Kum-Kang

    2018-05-08

    A system and method for heating ferrite permanent magnets in an electrical machine is disclosed. The permanent magnet machine includes a stator assembly and a rotor assembly, with a plurality of ferrite permanent magnets disposed within the stator assembly or the rotor assembly to generate a magnetic field that interacts with a stator magnetic field to produce a torque. A controller of the electrical machine is programmed to cause a primary field current to be applied to the stator windings to generate the stator magnetic field, so as to cause the rotor assembly to rotate relative to the stator assembly. The controller is further programmed to cause a secondary current to be applied to the stator windings to selectively generate a secondary magnetic field, the secondary magnetic field inducing eddy currents in at least one of the stator assembly and the rotor assembly to heat the ferrite permanent magnets.

  14. Diffusive heat transport across magnetic islands and stochastic layers in tokamaks

    International Nuclear Information System (INIS)

    Hoelzl, Matthias

    2010-01-01

    Heat transport in tokamak plasmas with magnetic islands and ergodic field lines was simulated at realistic plasma parameters in realistic tokamak geometries. This requires the treatment of anisotropic heat diffusion, which is more efficient along magnetic field lines by up to ten orders of magnitude than perpendicular to them. Comparisons with analytical predictions and experimental measurements allow to determine the stability properties of neoclassical tearing modes as well as the experimental heat diffusion anisotropy.

  15. Pressure drop and heat transfer of lithium single-phase flow under transverse magnetic field

    International Nuclear Information System (INIS)

    Takahashi, Minoru; Aritomi, Masanori; Inoue, Akira; Matsuzaki, Mitsuo

    1996-01-01

    Pressure drop and heat transfer characteristics of a lithium single-phase flow in a rectangular channel was investigated experimentally in the presence of a magnetic field. Friction loss coefficient under non-magnetic field and skin friction coefficient under magnetic field agreed well with the Blasius formula and a simple analytical expression, respectively. Nusselt number under non-magnetic field was slightly lower than the correlation by Hartnett and Irvine. Heat transfer was enhanced by increasing magnetic field above the Hartmann number of about 200. (author)

  16. Magnetic nanowires and hyperthermia: How geometry and material affect heat production efficiency

    KAUST Repository

    Contreras, Maria F.

    2015-05-01

    Magnetic hyperthermia, which refers to the production of heat by magnetic nanostructures under an alternating magnetic field (AMF), has been previously investigated with superparamagnetic nanobeads as a cancer therapy method. Magnetic nanowires (NWs) used in hyperthermia can be very promising, as it has been shown that they have a larger magnetic moment per unit of volume compared to the nanobeads. Moreover, Fe NWs proved to have a higher heating efficiency compared to Fe nanobeads, when exposed to an AMF at the same concentration [1].

  17. The effect of a magnetic field on heat transfer in a slotted channel

    International Nuclear Information System (INIS)

    Evtushenko, I.A.; Hua, T.Q.; Kirillov, I.R.; Reed, Claude B.; Sidorenkov, S.S.

    1995-01-01

    The results of numerical and experimental studies of liquid metal heat transfer in slotted channels in a transverse magnetic field are presented. Test results showed an improvement in heat transfer in a straight channel at low and moderate interaction parameter N. The Nusselt number at small N (around 120) was up to twofold higher than in turbulent flow without a magnetic field, the Peclet number being equal. This effect of heat transfer enhancement is caused by the generation and development of large-scale velocity fluctuations close to the heated wall area. Qualitative and quantitative correlations between heat transfer and velocity fluctuation characteristics are presented. (orig.)

  18. Tunable biasing magnetic field design of ferrite tuner for ICRF heating system in EAST

    Science.gov (United States)

    Manman, XU; Yuntao, SONG; Gen, CHEN; Yanping, ZHAO; Yuzhou, MAO; Guang, LIU; Zhen, PENG

    2017-11-01

    Ion cyclotron range of frequency (ICRF) heating has been used in tokamaks as one of the most successful auxiliary heating tools and has been adopted in the EAST. However, the antenna load will fluctuate with the change of plasma parameters in the ICRF heating process. To ensure the steady operation of the ICRF heating system in the EAST, fast ferrite tuner (FFT) has been carried out to achieve real-time impedance matching. For the requirements of the FFT impedance matching system, the magnet system of the ferrite tuner (FT) was designed by numerical simulations and experimental analysis, where the biasing magnetic circuit and alternating magnetic circuit were the key researched parts of the ferrite magnet. The integral design goal of the FT magnetic circuit is that DC bias magnetic field is 2000 Gs and alternating magnetic field is ±400 Gs. In the FTT, E-type magnetic circuit was adopted. Ferrite material is NdFeB with a thickness of 30 mm by setting the working point of NdFeB, and the ampere turn of excitation coil is 25 through the theoretical calculation and simulation analysis. The coil inductance to generate alternating magnetic field is about 7 mH. Eddy-current effect has been analyzed, while the magnetic field distribution has been measured by a Hall probe in the medium plane of the biasing magnet. Finally, the test results show the good performance of the biasing magnet satisfying the design and operating requirements of the FFT.

  19. Improved magnetic induction heating of nanoferrites for hyperthermia applications: Correlation with colloidal stability and magneto-structural properties

    Energy Technology Data Exchange (ETDEWEB)

    Khot, V.M., E-mail: wish_khot@yahoo.co.in [Center for Interdisciplinary Research, D. Y. Patil University, Kolhapur 416006 (India); Salunkhe, A.B. [Advanced Materials Laboratory, Department of Physics, Savitribai Phule University of Pune (India); Ruso, J.M. [Soft Matter and Molecular Biophysics Group, Applied Physics Department, University of Santiago de Compostela, Santiago de Compostela (Spain); Pawar, S.H. [Center for Interdisciplinary Research, D. Y. Patil University, Kolhapur 416006 (India)

    2015-06-15

    Nanoferrites with compositions Mn{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4}, Co{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4}, Ni{sub 0.4}Zn{sub 0.6}Fe{sub 2}O{sub 4} (MZF, CZF and NZF respectively) coated with polyethylene glycol (PEG) were prepared in a single step. These nanoparticles are highly water dispersible with zeta potential values between 14 and 21 mV. Magnetic induction heating characteristics of these NPs have been studied as a function of magnetic field amplitude from 6.7 to 26.7 kA m{sup −1} (at fixed frequency 265 kHz) and concentration of nanoparticles. Notable enhancement in specific absorption rate (334.5 W g{sup −1}) by CZF nanoparticles has been observed. This enhanced induction heating properties have been studied and correlated with colloidal stability and magnetostructural properties such as tuned magnetic anisotropy arising from zinc substitution. Cytotoxicity of synthesized mixed ferrites has been evaluated in vitro on HeLa cell lines using MTT assay to explore their use as heating agents in magnetic hyperthermia. - Highlights: • Magnetic nanoferrites (sizes 8–12 nm) with improved specific absorption rate (334.5 W g{sup −1}) at lowest particle concentration have been prepared • The results have been explained by correlating colloidal stability and magnetostructural properties such as magnetocrystalline anisotropy. • It has been shown that substitution of zinc tunes anisotropy of cobalt iron oxide within the value optimized previously in achieving high throughput in magnetic induction heating. • In vitro cytotoxicity proves nanoparticles are non-toxic suggesting their use as a potential heating agent in hyperthermia therapy.

  20. Improved magnetic induction heating of nanoferrites for hyperthermia applications: Correlation with colloidal stability and magneto-structural properties

    International Nuclear Information System (INIS)

    Khot, V.M.; Salunkhe, A.B.; Ruso, J.M.; Pawar, S.H.

    2015-01-01

    Nanoferrites with compositions Mn 0.4 Zn 0.6 Fe 2 O 4 , Co 0.4 Zn 0.6 Fe 2 O 4 , Ni 0.4 Zn 0.6 Fe 2 O 4 (MZF, CZF and NZF respectively) coated with polyethylene glycol (PEG) were prepared in a single step. These nanoparticles are highly water dispersible with zeta potential values between 14 and 21 mV. Magnetic induction heating characteristics of these NPs have been studied as a function of magnetic field amplitude from 6.7 to 26.7 kA m −1 (at fixed frequency 265 kHz) and concentration of nanoparticles. Notable enhancement in specific absorption rate (334.5 W g −1 ) by CZF nanoparticles has been observed. This enhanced induction heating properties have been studied and correlated with colloidal stability and magnetostructural properties such as tuned magnetic anisotropy arising from zinc substitution. Cytotoxicity of synthesized mixed ferrites has been evaluated in vitro on HeLa cell lines using MTT assay to explore their use as heating agents in magnetic hyperthermia. - Highlights: • Magnetic nanoferrites (sizes 8–12 nm) with improved specific absorption rate (334.5 W g −1 ) at lowest particle concentration have been prepared • The results have been explained by correlating colloidal stability and magnetostructural properties such as magnetocrystalline anisotropy. • It has been shown that substitution of zinc tunes anisotropy of cobalt iron oxide within the value optimized previously in achieving high throughput in magnetic induction heating. • In vitro cytotoxicity proves nanoparticles are non-toxic suggesting their use as a potential heating agent in hyperthermia therapy

  1. Effect of an alternating nonuniform magnetic field on ferrofluid flow and heat transfer in a channel

    International Nuclear Information System (INIS)

    Goharkhah, Mohammad; Ashjaee, Mehdi

    2014-01-01

    Forced convective heat transfer of water based Fe 3 O 4 nanofluid (ferrofluid) in the presence of an alternating non-uniform magnetic field is investigated numerically. The geometry is a two-dimensional channel which is subjected to a uniform heat flux at the top and bottom surfaces. Nonuniform magnetic field produced by eight line source dipoles is imposed on several parts of the channel. Also, a rectangular wave function is applied to the dipoles in order to turn them on and off alternatingly. The effects of the alternating magnetic field strength and frequency on the convective heat transfer are investigated for four different Reynolds numbers (Re=100, 600, 1200 and 2000) in the laminar flow regime. Comparing the results with zero magnetic field case, show that the heat transfer enhancement increases with the Reynolds number and reaches a maximum of 13.9% at Re=2000 and f=20 Hz. Moreover, at a constant Reynolds number, it increases with the magnetic field intensity while an optimum value exists for the frequency. Also, the optimum frequency increases with the Reynolds number. On the other hand, the heat transfer enhancement due to the magnetic field is always accompanied by a pressure drop penalty. A maximum pressure drop increase of 6% is observed at Re=2000 and f=5 Hz which shows that the pressure drop increase is not as significant as the heat transfer enhancement. - Highlights: • An alternating magnetic field is imposed on ferrofluid flow in a heated channel. • Heat transfer is enhanced noticeably compared to the case with no magnetic field. • Heat transfer depends on Reynolds number, magnetic field intensity and frequency. • Optimum frequency is independent of intensity but increases with Reynolds number. • Pressure drop increase is not as significant as the heat transfer enhancement

  2. Thermal fluctuations in the classical superconductor Nb3Sn from high-resolution specific-heat measurements

    International Nuclear Information System (INIS)

    Lortz, Rolf; Wang Yuxing; Junod, Alain; Toyota, Naoki

    2007-01-01

    The range of thermal fluctuations in 'classical' bulk superconductors is extremely small and especially in low-fields hardly experimentally accessible. With a new type of calorimeter we were able to detect a tiny lambda anomaly in the specific-heat of the superconductor Nb 3 Sn within a narrow temperature range around the H c2 line. We show that the evolution of the anomaly as a function of magnetic field follows scaling laws expected in the presence of critical thermal fluctuations

  3. Investigation of structure, specific heat and superconducting transition in Mg1-xAlxB2(x∼0.5)

    International Nuclear Information System (INIS)

    Xiang, J.Y.; Zheng, D.N.; Lang, P.L.; Zhao, Z.X.; Luo, J.L.

    2004-01-01

    We have carried out structure, magnetic and specific heat measurements on aluminum doped magnetism diboride samples Mg 1-x Al x B 2 in order to investigate possible superconductivity at the x=0.5 concentration. A diamagnetic signal was observed in magnetization measurements accompanied by a decrease in resistivity. However, the diamagnetic signal was extremely small as compared to what expected from full diamagnetism. Also, the transition both in magnetization and resistance was very broad. We propose that the diamagnetism is due to a very small amount of superconducting phase such as MgB 2 and the resistive transition is due to the percolation behavior. Furthermore, we performed specific heat measurements, which are considered as a tool to investigate the bulk nature of superconducting transition, on the x=0.5 sample to verify the existence of superconductivity. We observed no evident superconducting transition in the entire temperature region from 2 to 300 K. The undistinguishable data between 0 and 5 T magnetic fields also indicated the absence of bulk superconductivity in the x=0.5 sample

  4. Modeling and impacts of the latent heat of phase change and specific heat for phase change materials

    Science.gov (United States)

    Scoggin, J.; Khan, R. S.; Silva, H.; Gokirmak, A.

    2018-05-01

    We model the latent heats of crystallization and fusion in phase change materials with a unified latent heat of phase change, ensuring energy conservation by coupling the heat of phase change with amorphous and crystalline specific heats. We demonstrate the model with 2-D finite element simulations of Ge2Sb2Te5 and find that the heat of phase change increases local temperature up to 180 K in 300 nm × 300 nm structures during crystallization, significantly impacting grain distributions. We also show in electrothermal simulations of 45 nm confined and 10 nm mushroom cells that the higher amorphous specific heat predicted by this model increases nucleation probability at the end of reset operations. These nuclei can decrease set time, leading to variability, as demonstrated for the mushroom cell.

  5. Frictional Heating with Time-Dependent Specific Power of Friction

    Directory of Open Access Journals (Sweden)

    Topczewska Katarzyna

    2017-06-01

    Full Text Available In this paper analytical solutions of the thermal problems of friction were received. The appropriate boundary-value problems of heat conduction were formulated and solved for a homogeneous semi–space (a brake disc heated on its free surface by frictional heat fluxes with different and time-dependent intensities. Solutions were obtained in dimensionless form using Duhamel's theorem. Based on received solutions, evolution and spatial distribution of the dimensionless temperature were analyzed using numerical methods. The numerical results allowed to determine influence of the time distribution of friction power on the spatio-temporal temperature distribution in brake disc.

  6. Theory of free-electron-laser heating and current drive in magnetized plasmas

    International Nuclear Information System (INIS)

    Cohen, B.I.; Cohen, R.H.; Nevins, W.M.; Rognlien, T.D.

    1991-01-01

    The introduction of a powerful new microwave source, the free-electron laser, provides new opportunities for novel heating and current-drive schemes to be used in toroidal fusion devices. This high-power, pulsed source has a number of technical advantages for these applications, and its use is predicted to lead to improved current-drive efficiencies and opacities in reactor-grade fusion plasmas in specific cases. The Microwave Tokamak Experiment at the Lawrence Livermore National Laboratory will provide a test for some of these new heating and current-drive schemes. Although the motivation for much of this research has derived from the application of a free-electron laser to the heating of a tokamak plasma at a frequency near the electron cyclotron frequency, the underlying physics, i.e., the highly nonlinear interaction of an intense, pulsed, coherent electromagnetic wave with an electron in a magnetized plasma including relativistic effects, is of general interest. Other relevant applications include ionospheric modification by radio-frequency waves, high-energy electron accelerators, and the propagation of intense, pulsed electromagnetic waves in space and astrophysical plasmas. This review reports recent theoretical progress in the analysis and computer simulation of the absorption and current drive produced by intense pulses, and of the possible complications that may arise, e.g., parametric instabilities, nonlinear self-focusing, trapped-particle sideband instability, and instabilities of the heated plasma

  7. House owners' perceptions and factors influencing their choice of specific heating systems in Germany

    International Nuclear Information System (INIS)

    Decker, Thomas; Menrad, Klaus

    2015-01-01

    Against the background of global climate changes and several legal obligations, the target of this paper is to analyze the buying behavior of house owners in Germany with respect to heating systems and the main factors influencing choice when purchasing a specific heating system (e.g., oil heating or wood pellet heating). To investigate these issues, a Germany-wide written survey was conducted and the completed questionnaires of 775 respondents analyzed using multinomial logistic regression. Of 29 different variables influencing the purchase of a heating system, 12 statistically significant variables have been identified which characterize the owners of oil heating, a heat pump, gas heating and wood pellet heating. The membership of different ecological clusters primarily segregates the owners of a specific heating system, but the assessment of the different combustibles also plays a major role in this context. Suppliers of heating systems can use the results of this study to fine-tune their marketing strategies. With respect to policy issues only limited room for additional economic incentives can be identified to promote replacement of fossil-fuel based heating systems in favor of renewable ones. -- Highlights: •Current regulations support renewable heating systems insufficiently in Germany. •We developed a model to characterize the purchasers of different heating systems. •Ecological attitudes differentiate the purchasers of the different heating systems. •Economic reasons are mainly important for owners of gas and oil heating systems

  8. Specific heat of single crystalline YBa2Cu3O7 in 20 Tesla

    International Nuclear Information System (INIS)

    Bonjour, E.; Calemczuk, R.; Henry, J.Y.; Muller, J.; Triscone, G.; Vallier, J.C.

    1993-01-01

    The specific heat of a single crystal of YBa 2 Cu 3 0 7 is measured from 40 to 150 K in magnetic fields up to 20 Tesla applied either parallel or normal to the c axis. Adiabatic calorimetry with a scatter well below 0.1% is used. The scaling of the superconducting transitions determines the bulk anisotropy ratio 5.5±0.5. A Maki-like term is observed at intermediate temperatures. The unusual behaviour of YBa 2 Cu 3 0 7 in a field, featuring a considerable smearing of the transition and an apparently field-independent onset, may be qualitatively understood as a phenomenological consequence of the small and anisotropic value of the coherence length alone, using the relevant models of field-induced critical I-D fluctuations on one hand, and London-like regime for the mean-field part of the transition on the other hand

  9. Specific heat of single crystalline YBa2Cu3O7 in 20 Tesla

    International Nuclear Information System (INIS)

    Junod, A.; Bonjour, E.; Calemczuk, R.; Henry, J.Y.; Muller, J.; Triscone, G.; Vallier, J.C.

    1994-01-01

    The specific heat of a single crystal of YBa 2 Cu 3 O 7 is measured from 40 to 150 K in magnetic fields up to 20 Tesla applied either parallel or normal to the c axis. Adiabatic calorimetry with a scatter well below 0.1% is used. The scaling of the superconducting transitions determines the bulk anisotropy ratio, 5.5±0.5. A Maki-like term is observed at intermediate temperatures. The unusual behaviour of YBa 2 Cu 3 O 7 in a field, featuring a considerable smearing of the transition and an apparently field-independent onset, may be qualitatively understood as a phenomenological consequence of the small and anisotropic value of the coherence length alone, using the relevant models of field-induced critical 1-D fluctuations on one hand, and London-like regime for the mean-field part of the transition on the other hand. (orig.)

  10. Specific absorption rate determination of magnetic nanoparticles through hyperthermia measurements in non-adiabatic conditions

    Energy Technology Data Exchange (ETDEWEB)

    Coïsson, M. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Barrera, G. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); University of Torino, Chemistry Department, via P. Giuria 7, 10125 Torino (Italy); Celegato, F.; Martino, L.; Vinai, F. [INRIM, strada delle Cacce 91, 10135 Torino (Italy); Martino, P. [Politronica srl, via Livorno 60, 10144 Torino (Italy); Ferraro, G. [Center for Space Human Robotics, Istituto Italiano di Tecnologia - IIT, corso Trento 21, 10129 Torino (Italy); Tiberto, P. [INRIM, strada delle Cacce 91, 10135 Torino (Italy)

    2016-10-01

    An experimental setup for magnetic hyperthermia operating in non-adiabatic conditions is described. A thermodynamic model that takes into account the heat exchanged by the sample with the surrounding environment is developed. A suitable calibration procedure is proposed that allows the experimental validation of the model. Specific absorption rate can then be accurately determined just from the measurement of the sample temperature at the equilibrium steady state. The setup and the measurement procedure represent a simplification with respect to other systems requiring calorimeters or crucial corrections for heat flow. Two families of magnetic nanoparticles, one superparamagnetic and one characterised by larger sizes and static hysteresis, have been characterised as a function of field intensity, and specific absorption rate and intrinsic loss power have been obtained. - Highlights: • Development and thermodynamic modelling of a hyperthermia setup operating in non-adiabatic conditions. • Calibration of the experimental setup and validation of the model. • Accurate measurement of specific absorption rate and intrinsic loss power in non-adiabatic conditions.

  11. On a specific feature of heat transfer to organic coolants

    International Nuclear Information System (INIS)

    Kafengauz, N.L.; Gladkikh, V.A.

    1986-01-01

    Heat transfer to organic coolants, which is accompanied by solid carbon deposit formation, is experimentally studied. Polished and rough steel tubes with 3 mm outside diameter and 0.5 mm wall thickness, heated by electric current, were used as fuel elements. Results of experiments with kerosene T-1 are presented under the following regime parameters: pressure - 45 b; flow rate - 3.75 m/s; temperature - 25-40 deg C; fuel element temperature - 400-900 deg C. In experiments on fuel elements with natural roughness deposit formation caused a smooth increase of the wall temperature. In fuel elements with polished surface, deposit formation caused during the first minutes the reduction of the wall temperature and after that it increased. Intensity of solid deposit formation in fuel elements with polished and rough surface was the same. Similar results were observed not only in experiments with kerosene T-1, but with other organic fluids as well: with toluene, n-heptane, diisopropylcyclohexane etc. The results obtained can be explained in the following way. Solid deposits on a smooth surface create roughness which improves heat exchange and reduces, respectively, the heating surface temperature. But deposits possess weak heat conductivity and create additional thermal resistance, which aggravates heat exchange. Interaction of these two factors causes the complicated time dependence of wall temperature

  12. Specific heat of the 38-K superconductor MgB_2 in the normal and superconducting state: bulk evidence for a double gap

    OpenAIRE

    Junod, Alain; Wang, Yuxing; Bouquet, Frederic; Toulemonde, Pierre

    2001-01-01

    The specific heat of two polycrystalline samples of MgB_2 is presented and analyzed (2 - 300 K, 0 - 16 T), together with magnetic properties. The main characteristics are a low density of states at the Fermi level, high phonon frequencies, and an anomalous temperature- and field- dependence of the specific heat at T < T_c. A two-gap model with a gap ratio of 3:1 fits the specific heat in zero field. The smaller gap is washed out by a field of 0.5 T.

  13. Consideration on nuclear fusion in plasma by the magnetic confinement as a heat engine

    International Nuclear Information System (INIS)

    Tsuji, Yoshio

    1990-01-01

    In comparing nuclear fusion in plasma by the magnetic confinement with nuclear fission and chemical reactions, the power density and the function of a heat engine are discussed using a new parameter G introduced as an eigenvalue of a reaction and the value of q introduced to estimate the thermal efficiency of a heat engine. It is shown that the fusion reactor by the magnetic confinement is very difficult to be a modern heat engine because of the lack of some indispensable functions as a modern heat engine. The value of G and q have the important role in the consideration. (author)

  14. Magnetic behaviors of cataclasites within Wenchuan earthquake fault zone in heating experiments

    Science.gov (United States)

    Zhang, L.; Li, H.; Sun, Z.; Chou, Y. M.; Cao, Y., Jr.; Huan, W.; Ye, X.; He, X.

    2017-12-01

    Previous rock magnetism of fault rocks were used to trace the frictional heating temperature, however, few studies are focus on different temperatures effect of rock magnetic properties. To investigate rock magnetic response to different temperature, we conducted heating experiments on cataclasites from the Wenchuan earthquake Fault Scientific Drilling borehole 2 (WFSD-2) cores. Samples of cataclasites were obtained using an electric drill with a 1 cm-diameter drill pipe from 580.65 m-depth. Experiments were performed by a Thermal-optical measurement system under argon atmosphere and elevated temperatures. Both microstructural observations and powder X-ray diffraction analyses show that feldspar and quartz start to melt at 1100 ° and 1300 ° respectively. Magnetic susceptibility values of samples after heating are higher than that before heating. Samples after heating at 700 and 1750 ° have the highest values of magnetic susceptibility. Rock magnetic measurements show that the main ferromagnetic minerals within samples heated below 1100 ° (400, 700, 900 and 1100 °) are magnetite, which is new-formed by transformation of paramagnetic minerals. The χferri results show that the quantity of magnetite is bigger at sample heated by 700° experiment than by 400, 900 and 1100° experiments. Based on the FORC diagrams, we consider that magnetite grains are getting finer from 400 to 900°, and growing coarser when heated from 900 to 1100 °. SEM-EDX results indicate that the pure iron are formed in higher temperature (1300, 1500 and 1750 °), which present as framboids with size values of samples when heated at 400, 700, 900 and 1100°, while the neoformed pure iron is responsible to the higher magnetic susceptibility values of samples when heated at 1300, 1500 and 1750°.

  15. Nanocalorimeter platform for in situ specific heat measurements and x-ray diffraction at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Willa, K. [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Diao, Z. [Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden; Laboratory of Mathematics, Physics and Electrical Engineering, Halmstad University, P.O. Box 823, SE-301 18 Halmstad, Sweden; Campanini, D. [Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden; Welp, U. [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Divan, R. [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Hudl, M. [Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden; Islam, Z. [X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Kwok, W. -K. [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Rydh, A. [Department of Physics, Stockholm University, SE-106 91 Stockholm, Sweden

    2017-12-01

    Recent advances in electronics and nanofabrication have enabled membrane-based nanocalorimetry for measurements of the specific heat of microgram-sized samples. We have integrated a nanocalorimeter platform into a 4.5 T split-pair vertical-field magnet to allow for the simultaneous measurement of the specific heat and x-ray scattering in magnetic fields and at temperatures as low as 4 K. This multi-modal approach empowers researchers to directly correlate scattering experiments with insights from thermodynamic properties including structural, electronic, orbital, and magnetic phase transitions. The use of a nanocalorimeter sample platform enables numerous technical advantages: precise measurement and control of the sample temperature, quantification of beam heating effects, fast and precise positioning of the sample in the x-ray beam, and fast acquisition of x-ray scans over a wide temperature range without the need for time-consuming re-centering and re-alignment. Furthermore, on an YBa2Cu3O7-delta crystal and a copper foil, we demonstrate a novel approach to x-ray absorption spectroscopy by monitoring the change in sample temperature as a function of incident photon energy. Finally, we illustrate the new insights that can be gained from in situ structural and thermodynamic measurements by investigating the superheated state occurring at the first-order magneto-elastic phase transition of Fe2P, a material that is of interest for magnetocaloric applications.

  16. Specific heat and AC susceptibility of antiferromagnetic Kondo lattices CeAu.sub.2./sub.Si.sub.2./sub. and CeAg.sub.2./sub.Si.sub.2./sub..

    Czech Academy of Sciences Publication Activity Database

    Šantavá, Eva; Vejpravová, J.; Honda, F.; Komatsubara, T.; Sechovský, V.

    2007-01-01

    Roč. 310, - (2007), e586-e588 ISSN 0304-8853 Institutional research plan: CEZ:AV0Z10100520 Keywords : CeT 2 Si 2 * magnetic phase transition * magnetization * specific heat Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.704, year: 2007

  17. The Effect of Heat Treatment on the Crystallography and Mineral Magnetism of Pyrrhotite

    Science.gov (United States)

    Hobart, K.; Feinberg, J. M.; Jones, D. S.

    2017-12-01

    Pyrrhotite (Fe1-xS, 0 ≤ x ≤ 0.125) is the second most common sulfide mineral after pyrite in the Earth's crust, and its properties are of interest to a wide variety of scientific disciplines, including electrical engineering, physical chemistry, planetary geology and meteoritics, and economic geology. The physical properties of pyrrhotite are highly dependent on slight variations in composition and the ordering of iron vacancies, resulting in a number of possible phases between the endmember compositions of FeS and Fe7S8­­. A common complication in studies on pyrrhotite is that different phases are frequently intergrown, making it difficult to isolate a natural single phase. This has led many researchers to rely on synthesis techniques, which produce a specific structure by using precise iron/sulfur ratios, heating protocols, and controlled cooling. One of the most common synthesis treatments used to create 4C pyrrhotite is an extended heating and annealing process, which is believed to allow the reordering of vacancies to a more thermodynamically stable, ordered state with elevated saturation magnetization. The process was first studied in detail by Schwarz and Vaughan (1972) who produced synthetic pyrrhotite at varying Fe/S ratios with annealing at either 700, 300, or 144°C. The most common method for producing 4C pyrrhotite is heating at 500°C for 24 hours under a vacuum followed by annealing at 250°C for 50 hours. While this technique has been broadly applied in diverse disciplines, there is debate about whether it produces ferrimagnetic, monoclinic 4C pyrrhotite or a different metastable disordered phase. We examined this process using a combination of rock magnetic, X-ray diffraction, and electron imaging techniques to study the effect of heating and annealing on a natural sample of pyrrhotite. Due to the lack of a Besnus transition in the annealed material, our data suggest that the increased magnetization we found following annealing, rather than

  18. Joining of parts via magnetic heating of metal aluminum powders

    Science.gov (United States)

    Baker, Ian

    2013-05-21

    A method of joining at least two parts includes steps of dispersing a joining material comprising a multi-phase magnetic metal-aluminum powder at an interface between the at least two parts to be joined and applying an alternating magnetic field (AMF). The AMF has a magnetic field strength and frequency suitable for inducing magnetic hysteresis losses in the metal-aluminum powder and is applied for a period that raises temperature of the metal-aluminum powder to an exothermic transformation temperature. At the exothermic transformation temperature, the metal-aluminum powder melts and resolidifies as a metal aluminide solid having a non-magnetic configuration.

  19. Magnetic nanoparticles for targeted therapeutic gene delivery and magnetic-inducing heating on hepatoma

    International Nuclear Information System (INIS)

    Yuan, Chenyan; Zhang, Jia; Li, Hongbo; Zhang, Hao; Wang, Ling; Zhang, Dongsheng; An, Yanli

    2014-01-01

    Gene therapy holds great promise for treating cancers, but their clinical applications are being hampered due to uncontrolled gene delivery and expression. To develop a targeted, safe and efficient tumor therapy system, we constructed a tissue-specific suicide gene delivery system by using magnetic nanoparticles (MNPs) as carriers for the combination of gene therapy and hyperthermia on hepatoma. The suicide gene was hepatoma-targeted and hypoxia-enhanced, and the MNPs possessed the ability to elevate temperature to the effective range for tumor hyperthermia as imposed on an alternating magnetic field (AMF). The tumoricidal effects of targeted gene therapy associated with hyperthermia were evaluated in vitro and in vivo. The experiment demonstrated that hyperthermia combined with a targeted gene therapy system proffer an effective tool for tumor therapy with high selectivity and the synergistic effect of hepatoma suppression. (paper)

  20. Experimental study on heat transfer augmentation of graphene based ferrofluids in presence of magnetic field

    DEFF Research Database (Denmark)

    Sadeghinezhad, Emad; Mehrali, Mohammad; Akhiani, Amir Reza

    2017-01-01

    The effect of a permanent magnetic field on the heat transfer characteristics of hybrid graphene-magnetite nanofluids (hybrid nanofluid) under forced laminar flow was experimentally investigated. For this purpose, a reduced graphene oxide-Fe3O4 was synthesized by using two-dimensional (2D) graphene...... and it shows that the thermal conductivity increased up to 11%. The hybrid nanofluid behaves as a Newtonian fluid with liquid like behavior with superparamagnetic properties as was evident from its magnetic saturation value at 45.9 emu/g. Moreover, the experimental heat-transfer results indicated that the heat...... transfer enhancement of the hybrid nanofluid compared to the control fluid (distilled water) was negligible when no magnetic field was applied. Additionally, the convective heat transfer was significantly improved under the influence of a magnetic field with a maximum enhancement of 82% in terms...

  1. Role of Magnetic Carpet in Coronal Heating S. R. Verma & Diksha ...

    Indian Academy of Sciences (India)

    It is likely that different heating mechanisms are at work in the solar corona. ... ity, termed magnetic carpet contributing to solar activity on a short time .... migrates to the boundaries of supergranule cells and moves along them, fragmenting,.

  2. Effect of heat treatment on the microstructure and properties of Ni based soft magnetic alloy.

    Science.gov (United States)

    Li, Chunhong; Ruan, Hui; Chen, Dengming; Li, Kejian; Guo, Donglin; Shao, Bin

    2018-04-20

    A Ni-based alloy was heat treated by changing the temperature and ambient atmosphere of the heat treatment. Morphology, crystal structure, and physical performance of the Ni-based alloy were characterized via SEM, XRD, TEM, and PPMS. Results show that due to the heat treatment process, the grain growth of the Ni-based alloy and the removal of impurities and defects are promoted. Both the orientation and stress caused by rolling are reduced. The permeability and saturation magnetization of the alloy are improved. The hysteresis loss and coercivity are decreased. Higher heat treatment temperature leads to increased improvement of permeability and saturation magnetization. Heat treatment in hydrogen is more conducive to the removal of impurities. At the same temperature, the magnetic performance of the heat-treated alloy in hydrogen is better than that of an alloy with heat treatment in vacuum. The Ni-based alloy shows an excellent magnetic performance on 1,373 K heat treatment in hydrogen atmosphere. In this process, the µ m , B s , P u , and H c of the obtained alloy are 427 mHm -1 , 509 mT, 0.866 Jm -3 , and 0.514 Am -1 , respectively. At the same time, the resistivity of alloy decreases and its thermal conductivity increases in response to heat treatment. © 2018 Wiley Periodicals, Inc.

  3. Feedlot cattle susceptibility to heat stress: an animal specific model

    Science.gov (United States)

    The extreme effects of heat stress in a feedlot situation can cause losses exceeding 5% of all the cattle on feed in a single feedlot. These losses can be very devastating to a localized area of feedlot producers. Animal stress is a result of the combination of three different components: environm...

  4. Effects of heat transfer, friction and variable specific heats of working fluid on performance of an irreversible dual cycle

    International Nuclear Information System (INIS)

    Chen Lingen; Ge Yanlin; Sun Fengrui; Wu Chih

    2006-01-01

    The thermodynamic performance of an air standard dual cycle with heat transfer loss, friction like term loss and variable specific heats of working fluid is analyzed. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle, are derived by detailed numerical examples. Moreover, the effects of variable specific heats of the working fluid and the friction like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific heats of working fluid and friction like term loss on the cycle performance are obvious, and they should be considered in practical cycle analysis. The results obtained in this paper may provide guidance for the design of practical internal combustion engines

  5. Performance of an Atkinson cycle with heat transfer, friction and variable specific-heats of the working fluid

    International Nuclear Information System (INIS)

    Ge Yanlin; Chen Lingen; Sun, Fengrui; Wu Chih

    2006-01-01

    The performance of an air standard Atkinson cycle with heat-transfer loss, friction-like term loss and variable specific-heats of the working fluid is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between the power output and the efficiency of the cycle are derived by detailed numerical examples. Moreover, the effects of variable specific-heats of the working fluid and the friction-like term loss on the irreversible cycle performance are analyzed. The results show that the effects of variable specific-heats of working fluid and friction-like term loss on the irreversible cycle performance should be considered in cycle analysis. The results obtained in this paper provide guidance for the design of Atkinson engines

  6. A multi-functional testing instrument for heat assisted magnetic recording media

    International Nuclear Information System (INIS)

    Yang, H. Z.; Chen, Y. J.; Leong, S. H.; An, C. W.; Ye, K. D.; Hu, J. F.; Yin, M. J.

    2014-01-01

    With recent developments in heat assisted magnetic recording (HAMR), characterization of HAMR media is becoming very important. We present a multi-functional instrument for testing HAMR media, which integrates HAMR writing, reading, and a micro-magneto-optic Kerr effect (μ-MOKE) testing function. A potential application of the present instrument is to make temperature dependent magnetic property measurement using a pump-probe configuration. In the measurement, the media is heated up by a heating (intense) beam while a testing (weak) beam is overlapped with the heating beam for MOKE measurement. By heating the media with different heating beam power, magnetic measurements by MOKE at different temperatures can be performed. Compared to traditional existing tools such as the vibrating sample magnetometer, the present instrument provides localized and efficient heating at the measurement spot. The integration of HAMR writing and μ-MOKE system can also facilitate a localized full investigation of the magnetic media by potential correlation of HAMR head independent write/read performance to localized magnetic properties

  7. Beam heating studies on an early model is a superconducting cosine theta magnet

    International Nuclear Information System (INIS)

    Bozoki, G.; Bunce, G.; Danby, G.; Foelsche, H.; Jackson, J.; Prodell, A.; Soukas, A.; Stevens, A.; Stoehr, R.; Weisenbloom, J.

    1980-01-01

    Superconducting magnets for accelerators can be accidentally quenched by heat resulting from beam losses in the magnet. The threshold for such quenches is determined by the time structure of the beam loss and by details of the magnet application, construction and cooling. A 4.25 m long superconducting cosine theta dipole magnet, MARK VI, constructed during the research and development phase of the ISABELLE Project at BNL was installed in the 28.5 GeV/c primary proton beam line from the AGS. By energizing the magnet, the proton beam could be deflected into the magnet. The beam intensity required to quench the magnet was observed for different beam sizes and at several values of magnet current up to 2400 A or approximately 70% of the highest magnet operating current. The maximum current was limited by the gas-cooled power lead flow available using pool-boiling helium rather than single phase forced-flow helium at 5 atm for which the magnet system was designed. Details of the experimental setup including the magnet and cryogenic system, the beam-monitoring equipment and instrumentation are described. The measurements are discussed and compared with beam heating measurements made on another superconducting magnet and interpreted using the Cascade Simulation Program, CASIM

  8. Experimental determination of nanofluid specific heat with SiO2 nanoparticles in different base fluids

    Science.gov (United States)

    Akilu, S.; Baheta, A. T.; Sharma, K. V.; Said, M. A.

    2017-09-01

    Nanostructured ceramic materials have recently attracted attention as promising heat transfer fluid additives owing to their outstanding heat storage capacities. In this paper, experimental measurements of the specific heats of SiO2-Glycerol, SiO2-Ethylene Glycol, and SiO2-Glycerol/Ethylene Glycol mixture 60:40 ratio (by mass) nanofluids with different volume concentrations of 1.0-4.0% have been carried out using differential scanning calorimeter at temperatures of 25 °C and 50 °C. Experimental results indicate lower specific heat capacities are found with SiO2 nanofluids compared to their respective base fluids. The specific heat was decreasing with the increase of concentration, and this decrement depends on upon the type of the base fluid. It is observed that temperature has a positive impact on the specific heat capacity. Furthermore, the experimental values were compared with the theoretical model predictions, and a satisfactory agreement was established.

  9. Experimental investigation of MHD heat transfer in a vertical round tube affected by transverse magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Melnikov, I.A., E-mail: corpuskula@gmail.com; Sviridov, E.V.; Sviridov, V.G.; Razuvanov, N.G.

    2016-11-15

    Highlights: • Local and averaged heat transfer coefficient are measured. • Free convection influence on MHD-flow is investigated. • The region with the free convection effect of MHD-heat transfer is found. • Temperature low-frequency fluctuations of abnormally high amplitude are detected. • Analysis of the MHD-heat transfer experimental data is performed. - Abstract: The article is devoted to the results of experimental investigation of heat transfer for a downward mercury flow in a vertical round tube in the presence of a transverse magnetic with non-uniform heat flux along the tube circumference.

  10. Low-temperature specific heat of the quasi-two-dimensional charge-density wave compound KMo6O17

    Science.gov (United States)

    Wang, Junfeng; Xiong, Rui; Yin, Di; Li, Changzhen; Tang, Zheng; Wang, Ququan; Shi, Jing; Wang, Yue; Wen, Haihu

    2006-05-01

    Low temperature specific heat (Cp) of quasi-two-dimensional charge-density wave (CDW) compound KMo6O17 has been studied by a relaxation method from 2to48K under zero and 12T magnetic fields. The results show that no specific heat anomaly is found at 16K under both zero and 12T magnetic fields, although an anomaly is clearly observed in the resistivity and magnetoresistance measurements. From the data between 2 and 4K , the density of states at Fermi level is estimated as 0.2eV-1permolecule and the Debye temperature is extracted to be 418K . A bump appearing in Cp/T3 is found between 4 and 48K centered around 12.5-15K , indicating that the phason excitations contribute to the total specific heat similarly as in quasi-one-dimensional CDW conductors. Using a modified Debye model, a pinning frequency of 0.73THz for KMo6O17 is estimated from the phason contribution.

  11. Regarding the influence of heating and the Soret effect on a magnetic fluid seal

    Energy Technology Data Exchange (ETDEWEB)

    Krakov, M.S., E-mail: mkrakov@gmail.com [Belarusian National Technical University, 65 Independence Ave., 220013 Minsk (Belarus); Nikiforov, I.V. [Belarusian State University, 4 Independence Sq., 220050 Minsk (Belarus)

    2017-06-01

    The influence of a temperature gradient and the Soret effect on the distribution of particles in a magnetic fluid seal (MFS) is studied. The heating of the MFS is found to be an effective method of homogenizing the magnetic fluid in the seal; in addition, the influence of the Soret effect on this process is found to be essential.

  12. The Hardy inequality and the heat equation with magnetic field in any dimension

    Czech Academy of Sciences Publication Activity Database

    Cazacu, C.; Krejčiřík, David

    2016-01-01

    Roč. 41, č. 7 (2016), s. 1056-1088 ISSN 0360-5302 R&D Projects: GA ČR(CZ) GA14-06818S Institutional support: RVO:61389005 Keywords : Aharonov-Bohm magnetic field * Hardy inequality * heat equation * large time behaviour of solutions * magnetic Schrodinger operator Subject RIV: BE - Theoretical Physics Impact factor: 1.608, year: 2016

  13. Modulation of the wall-heat transfer in turbulent thermomagnetic convection by magnetic field gradients

    NARCIS (Netherlands)

    Kenjeres, S.; Zinsmeester, R.; Pyrda, L.; Fornalik-Wajs, E.; Szmyd, J.

    2015-01-01

    We present combined experimental and numerical studies of the heat transfer of paramagnetic or diamagnetic fluid inside a differentially heated cubical enclosure subjected to the magnetic field gradients of different strength and orientation. In contrast to the previously reported studies in

  14. Geothermal Heat Flux Underneath Ice Sheets Estimated From Magnetic Satellite Data

    DEFF Research Database (Denmark)

    Fox Maule, Cathrine; Purucker, M.E.; Olsen, Nils

    The geothermal heat flux is an important factor in the dynamics of ice sheets, and it is one of the important parameters in the thermal budgets of subglacial lakes. We have used satellite magnetic data to estimate the geothermal heat flux underneath the ice sheets in Antarctica and Greenland...

  15. Temperature Dependence and Magnetic Properties of Injection Molding Tool Materials Used in Induction Heating

    DEFF Research Database (Denmark)

    Guerrier, Patrick; Nielsen, Kaspar Kirstein; Hattel, Jesper Henri

    2015-01-01

    To analyze the heating phase of an induction heated injection molding tool precisely, the temperature-dependent magnetic properties, B–H curves, and the hysteresis loss are necessary for the molding tool materials. Hence, injection molding tool steels, core materials among other materials have...

  16. High Magnetic Field Processing - A Heat-Free Heat Treating Method

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard Michael [ORNL; Ludtka, Gail Mackiewicz- [ORNL; Wilgen, John B [ORNL; Kenik, Edward A [ORNL; Parish, Chad M [ORNL; Rios, Orlando [ORNL; Rogers, Hiram [ORNL; Manuel, Michele [University of Florida, Gainesville; Kisner, Roger A [ORNL; Watkins, Thomas R [ORNL; Murphy, Bart L [ORNL

    2012-08-01

    The High and Thermal Magnetic Processing/Electro-magnetic Acoustic Transducer (HTMP/EMAT) technology has been shown to be an enabling disruptive materials processing technology, that can achieve significant improvements in microstructure and consequently material performance beyond that achievable through conventional processing, and will lead to the next generation of advanced performance structural and functional materials. HTMP exposure increased the reaction kinetics enabling refinement of microstructural features such as finer martensite lath size, and finer, more copious, homogeneous dispersions of strengthening carbides leading to combined strength and toughness improvements in bainitic steels. When induction heating is applied in a high magnetic field environment, the induction heating coil is configured so that high intensity acoustic/ultrasonic treatment occurs naturally. The configuration results in a highly effective electromagnetic acoustical transducer (EMAT). HTMP combined with applying high-field EMAT, produce a non-contact ultrasonic treatment that can be used to process metal alloys in either the liquid state resulting in significant microstructural changes over conventional processing. Proof-of-principle experiments on cast irons resulted in homogeneous microstructures in small castings along with improved casting surface appearance. The experiment showed that by exposing liquid metal to the non-contact acoustic/ultrasonic processing technology developed using HMFP/EMAT wrought-like microstructures were developed in cast components. This Energy Intensive Processes (EIP) project sponsored by the DOE EERE Advanced Manufacturing Office (AMO) demonstrated the following: (1) The reduction of retained austenite in high carbon/high alloy steels with an ambient temperature HTMP process, replacing either a cryogenic or double tempering thermal process normally employed to accomplish retained austenite transformation. HTMP can be described as a 'heat

  17. Effects on heat transfer of multiphase magnetic fluid due to circular magnetic field over a stretching surface with heat source/sink and thermal radiation

    Directory of Open Access Journals (Sweden)

    A. Zeeshan

    Full Text Available The purpose of the current article is to explore the boundary layer heat transport flow of multiphase magnetic fluid with solid impurities suspended homogeneously past a stretching sheet under the impact of circular magnetic field. Thermal radiation effects are also taken in account. The equations describing the flow of dust particles in fluid along with point dipole are modelled by employing conservation laws of mass, momentum and energy, which are then converted into non-linear coupled differential equations by mean of similarity approach. The transformed ODE’s are tackled numerically with the help of efficient Runga-Kutta method. The influence of ferromagnetic interaction parameter, viscous dissipation, fluid-particle interaction parameter, Eckert number, Prandtl number, thermal radiation parameter and number of dust particles, heat production or absorption parameter with the two thermal process namely, prescribed heat flux (PHF or prescribed surface temperature (PST are observed on temperature and velocity profiles. The value of skin-friction coefficient and Nusselt number are calculated for numerous physical parameters. Present results are correlated with available for a limited case and an excellent agreement is found. Keywords: Ferromagnetic interaction parameter, Dusty magnetic fluid, stretching sheet, Magnetic dipole, Heat source/sink, Thermal radiation

  18. Same magnetic nanoparticles, different heating behavior: Influence of the arrangement and dispersive medium

    Energy Technology Data Exchange (ETDEWEB)

    Andreu, Irene [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Natividad, Eva, E-mail: evanat@unizar.es [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Solozábal, Laura [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Campus Río Ebro, María de Luna, 3, 50018 Zaragoza (Spain); Roubeau, Olivier [Instituto de Ciencia de Materiales de Aragón (ICMA), CSIC-Universidad de Zaragoza, Departamento de Física de la Materia Condensada, 50009 Zaragoza (Spain)

    2015-04-15

    The heating ability of the same magnetic nanoparticles (MNPs) dispersed in different media has been studied in the 170–310 K temperature range. For this purpose, the biggest non-twinned nanoparticles have been selected among a series of magnetite nanoparticles of increasing sizes synthesized via a seeded growth method. The sample with nanoparticles dispersed in n-tetracosane, thermally quenched from 100 °C and solid in the whole measuring range, follows the linear response theoretical behavior for non-interacting nanoparticles, and displays a remarkably large maximum specific absorption rate (SAR) value comparable to that of magnetosomes at the alternating magnetic fields used in the measurements. The other samples, with nanoparticles dispersed either in alkane solvents of sub-ambient melting temperatures or in epoxy resin, display different thermal behaviors and maximum SAR values ranging between 11 and 65% of that achieved for the sample with n-tetracosane as dispersive medium. These results highlight the importance of the MNPs environment and arrangement to maintain optimal SAR values, and may help to understand the disparity sometimes found between MNPs heating performance measured in a ferrofluid and after injection in an animal model, where MNP arrangement and environment are not the same. - Highlights: • We synthetize a series of Fe{sub 3}O{sub 4} nanoparticles by the seeded-growth method. • We characterize the heating ability of 13.9 nm particles dispersed in several media. • We apply SAR(T) characterization to locate the onset of superparamagnetic behavior. • The highest SAR values are obtained in low-concentration solid-alkane dispersion. • Acquired arrangements in different media strongly modify SAR trends and values.

  19. Influence of kondo effect on the specific heat jump of anisotropic superconductors

    Science.gov (United States)

    Yoksan, S.

    1986-01-01

    A calculation for the specific heat jump of an anisotropic superconductor with Kondo impurities is presented. The impurities are treated within the Matsuura - Ichinose - Nagaoka framework and the anisotropy effect is described by the factorizable model of Markowitz and Kadanoff. We give explicit expressions for the change in specific heat jump due to anisotropy and impurities which can be tested experimentally.

  20. Influence of Kondo effect on the specific heat jump of anisotropic superconductors

    International Nuclear Information System (INIS)

    Yoksan, S.

    1986-01-01

    A calculation for the specific heat jump of an anisotropic superconductor with Kondo impurities is presented. The impurities are treated within the Matsuura - Ichinose - Nagaoka framework and the anisotropy effect is described by the factorizable model of Markowitz and Kadanoff. Explicit expressions are given for the change in specific heat jump due to anisotropy and impurities which can be tested experimentally. (author)

  1. Silver oxides. II. Specific heats of silver oxide and silver peroxide. [20 to 99 C

    Energy Technology Data Exchange (ETDEWEB)

    Jirsa, F

    1949-01-01

    Specific heats were determined in a water calorimeter over the temperature range 20 through 99 C. The specific heat of Ag/sub 2/O is given as 0.0803 +- 0.001 cal/g-C, and that of Ag/sub 2/O/sub 2/ is given as 0.0869 +- 0.0005 cal/g-C.

  2. Cholangiocarcinoma in Cirrhosis: Value of Hepatocyte Specific Magnetic Resonance Imaging.

    Science.gov (United States)

    Piscaglia, Fabio; Iavarone, Massimo; Galassi, Marzia; Vavassori, Sara; Renzulli, Matteo; Forzenigo, Laura Virginia; Granito, Alessandro; Salvatore, Veronica; Sangiovanni, Angelo; Golfieri, Rita; Colombo, Massimo; Bolondi, Luigi

    2015-10-01

    The diagnosis of intrahepatic cholangiocellular carcinoma (ICC) remains elusive at imaging, which is a critical issue in cirrhotic patients in whom a diagnosis of hepatocellular carcinoma (HCC) can be established only by imaging. The aim of the study was to evaluate the potential of MRI in the diagnosis of ICC in cirrhosis using 'hepatocyte-specific' Gadolinium (Gd)-based contrast agents. Sixteen histologically proven and retrospectively identified ICCs on cirrhosis were investigated with hepatocyte-specific magnetic resonance contrast agents (6 in Bologna with Gd-EOB-DTPA and 10 in Milan with Gd-BOPTA). The control group consisted of 41 consecutively and prospectively collected nodules (31 HCCs) imaged with Gd-EOB-DTPA. Fifteen ICC nodules (94%) displayed hypointensity in the hepatobiliary phase, suggesting malignancy. Thirteen cholangiocarcinomas (81%) showed hyperenhancement in the venous phase. Only 2 cholangiocarcinoma nodules showed hypoenhancement in the venous phase, corresponding to washout, in both cases preceded by rim enhancement in arterial phase. All the hepatocarcinomas showed hypointensity in hepatobiliary phase, but was always preceded by hypointensity in the venous phase; arterial rim enhancement was never observed in any hepatocarcinoma or regenerative nodule. MRI with hepatocyte-specific Gd-based contrast agents showed a pattern of malignancy in almost all the ICCs, concurrently avoiding misdiagnosis with hepatocarcinoma. These findings suggest a greater diagnostic capacity for this technique compared with the results of MRI with conventional contrast agents reported in the literature in this setting. © 2015 S. Karger AG, Basel.

  3. Thermomagnetic force acting on an ellipsoidal body immersed into a nonuniformly heated magnetic liquid

    International Nuclear Information System (INIS)

    Naletova, V.A.; Kvitantsev, A.S.

    2002-01-01

    A prolate spheroidal body immersed into a nonuniformly heated magnetic liquid in an applied magnetic field has been considered. The expressions for the pressure and velocity of the liquid, temperature and magnetic field have been obtained. The formula for a thermomagnetic force acting on the body has been calculated. It has been shown that the body shape needs to be taken into account when we study the thermomagnetic diffusion of the prolate bodies

  4. Helium II heat transfer in LHC magnets : polyimide cable insulation

    NARCIS (Netherlands)

    Winkler, Tiemo

    2017-01-01

    Today’s large particle accelerators like the LHC at CERN are using superconducting materials as a construction material for magnets. These magnets need to be cooled constantly to temperatures below the critical surface of the superconducting material. In the LHC this is achieved by using liquid

  5. Simulation of cracks in tungsten under ITER specific heat loads

    International Nuclear Information System (INIS)

    Peschany, S.

    2006-01-01

    The problem of high tritium retention in co-deposited carbon layers on the walls of ITER vacuum chamber motivates investigation of materials for the divertor armour others than carbon fibre composite (CFC). Tungsten is most probable material for CFC replacement as the divertor armour because of high vaporisation temperature and heat conductivity. In the modern ITER design tungsten is a reference material for the divertor cover, except for the separatrix strike point armoured with CFC. As divertor armour, tungsten should withstand severe heat loads at off-normal ITER events like disruptions, ELMs and vertical displacement events. Experiments on tungsten heating with plasma streams and e-beams have shown an intense crack formation at the surface of irradiated sample [ V.I. Tereshin, A.N. Bandura, O.V. Byrka et al. Repetitive plasma loads typical for ITER type-I ELMs: Simulation at QSPA Kh-50.PLASMA 2005. ed. By Sadowski M.J., AIP Conference Proceedings, American Institute of Physics, 2006, V 812, p. 128-135., J. Linke. Private communications.]. The reason for tungsten cracking under severe heat loads is thermo stress. It appears as due to temperature gradient in solid tungsten as in resolidified layer after cooling down. Both thermo stresses are of the same value, but the gradiental stress is compressive and the stress in the resolidified layer is tensile. The last one is most dangerous for crack formation and it was investigated in this work. The thermo stress in tungsten that develops during cooling from the melting temperature down to room temperature is ∼ 8-16 GPa. Tensile strength of tungsten is much lower, < 1 GPa at room temperature, and at high temperatures it drops at least for one order of magnitude. As a consequence, various cracks of different characteristic scales appear at the heated surface of the resolidified layer. For simulation of the cracks in tungsten the numeric code PEGASUS-3D [Pestchanyi and I. Landman. Improvement of the CFC structure to

  6. Magnon heat capacity and magnetic susceptibility of the spin Lieb lattice

    Energy Technology Data Exchange (ETDEWEB)

    Yarmohammadi, Mohsen, E-mail: m.yarmohammadi69@gamil.com

    2016-11-01

    Using linear response theory, Heisenberg model Hamiltonian and Green's function technique, the influences of Dzyaloshinskii–Moriya interaction (DMI), external magnetic field and next-nearest-neighbor (NNN) coupling on the density of magnon modes (DMM), the magnetic susceptibility (MS) and the magnon heat capacity (MHC) of a spin Lieb lattice, a face-centered square lattice, are investigated. The results reveal a band gap in the DMM and we witness an extension in the bandwidth and an increase in the number of van-Hove singularities as well. As a notable point, besides the magnetic nature which includes ferromagnetism in spin Lieb-based nanosystems, MS is investigated. Further, we report a Schottky anomaly in the MHC. The results show that the effects of the magnetic field on the MHC and MS have different behaviors in two temperature regions. In the low temperature region, MHC and MS increase when the magnetic field strength increases. On the other hand, the MHC and MS reduce with increasing the magnetic field strength in the high temperature region. Also comprehensive numerical modelling of the DMM, the MS and the MHC of a spin Lieb lattice yields excellent qualitative agreement with the experimental data. - Highlights: • Theoretical calculation of density of states of the spin Lieb lattice. • The investigation of the effect of external magnetic field on the magnon heat capacity and magnetic susceptibility. • The investigation of the effect of NNN coupling and the DMI strength on the magnon heat capacity and magnetic susceptibility.

  7. Coronal Heating Topology: The Interplay of Current Sheets and Magnetic Field Lines

    Energy Technology Data Exchange (ETDEWEB)

    Rappazzo, A. F.; Velli, M. [Department of Earth, Planetary, and Space Sciences, UCLA, Los Angeles, CA 90095 (United States); Matthaeus, W. H. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States); Ruffolo, D. [Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400 (Thailand); Servidio, S., E-mail: rappazzo@ucla.edu [Dipartimento di Fisica, Università della Calabria, Cosenza I-87036 (Italy)

    2017-07-20

    The magnetic topology and field line random walk (FLRW) properties of a nanoflare-heated and magnetically confined corona are investigated in the reduced magnetohydrodynamic regime. Field lines originating from current sheets form coherent structures, called current sheet connected (CSC) regions, which extend around them. CSC FLRW is strongly anisotropic, with preferential diffusion along the current sheets’ in-plane length. CSC FLRW properties remain similar to those of the entire ensemble but exhibit enhanced mean square displacements and separations due to the stronger magnetic field intensities in CSC regions. The implications for particle acceleration and heat transport in the solar corona and wind, and for solar moss formation are discussed.

  8. Plasma heating and confinement in toroidal magnetic bottle by means of microwave slowing-down structure

    International Nuclear Information System (INIS)

    Datlov, J.; Klima, R.; Kopecky, V.; Musil, J.; Zacek, F.

    1977-01-01

    An invention is described concerning high-frequency plasma heating and confinement in toroidal magnetic vessels. Microwave energy is applied to the plasma via one or more slowing-down structures exciting low phase velocity waves whose energy may be efficiently absorbed by plasma electrons. The wave momentum transfer results in a toroidal electrical current whose magnetic field together with an external magnetic field ensure plasma confinement. The low-frequency modulation of microwave energy may also be used for heating the ion plasma component. (J.U.)

  9. Design and heat load analysis of support structure of CR superconducting dipole magnet for FAIR

    International Nuclear Information System (INIS)

    Zhu Yinfeng; Wu Songtao; Wu Weiyue; Xu Houchang; Liu Changle

    2008-01-01

    In order to meet the requirement of the Collector ring (CR) dipole superconducting magnet of FAIR in the process of operation, meanwhile, and to ensure the heat loads coming from the support structures to be lower than the design demands, the 3D models of support structures have been constructed with CATIA, then the calculation of low-temperature heat-load and the structure analysis have been done with ANSYS, the support structure material, 316LN+G10, is decided according to the heat-load calculation and the structure optimization, these results are necessary for manufacturing the formal magnet. (authors)

  10. Some specific features of subcooled boiling heat transfer and crisis at extremely high heat flux densities

    International Nuclear Information System (INIS)

    Gotovsky, M.A.

    2001-01-01

    Forced convection boiling is the process used widely in a lot of industry branches including NPP. Heat transfer intensity under forced convection boiling is considered in different way in dependence on conditions. One of main problems for the process considered is an influence of interaction between forced flow and boiling on heat transfer character. For saturated water case a transition from ''pure'' forced convection to nucleate boiling can be realized in smooth form. (author)

  11. Electro-magnetic heating in viscous oil reservoir

    Energy Technology Data Exchange (ETDEWEB)

    Das, S. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Marathon Oil Corp., Houston, TX (United States)

    2008-10-15

    This paper discussed electromagnetic (EM) heating techniques for primary and secondary enhanced oil recovery (EOR) processes. Ohmic, induction, and formation resistive heating techniques were discussed. Issues related to energy equivalence and hardware requirements were reviewed. Challenges related to heat losses in vertical wellbores, well integrity, and galvanic corrosion were also outlined. A pair of 1500 foot horizontal wells in a heavy oil reservoir were then modelled in order to optimize EM recovery processes. DC current was used in a base case water flood run. Electrical conductivities were measured. The model was converted to a homogenous model in order to study injector and producer electrodes. The study showed that reservoir resistance was low, and most of the heating took place near the electrode area where electric lines diverged or converged. Results of the study suggested that EM heating in formations is not as efficient as steam-based processes. Accurate simulations of EM heating processes within reservoirs are difficult to obtain, as the amounts of estimated heat input are sensitive to grid refinement. It was concluded that hot spots in the EM electrodes have also caused failures in other field applications and studies. 11 refs., 12 figs.

  12. Determination and Application of Comprehensive Specific Frictional Resistance in Heating Engineering

    Directory of Open Access Journals (Sweden)

    Yanan Tian

    2018-01-01

    Full Text Available In this study, we analyze the deficiencies of specific frictional resistance in heating engineering. Based on economic specific frictional resistance, we put forward the concept of comprehensive specific frictional resistance, which considers the multiple factors of technology, economy, regulation modes, pipe segment differences, and medium pressure. Then, we establish a mathematical model of a heating network across its lifespan in order to develop a method for determining the comprehensive specific frictional resistance. Relevant conclusions can be drawn from the results. As an application, we have planned the heating engineering for Yangyuan County in China, which demonstrates the feasibility and superiority of the method.

  13. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Science.gov (United States)

    Suzuki, Masashi; Aki, Atsushi; Mizuki, Toru; Maekawa, Toru; Usami, Ron; Morimoto, Hisao

    2015-01-01

    We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  14. Encouragement of Enzyme Reaction Utilizing Heat Generation from Ferromagnetic Particles Subjected to an AC Magnetic Field.

    Directory of Open Access Journals (Sweden)

    Masashi Suzuki

    Full Text Available We propose a method of activating an enzyme utilizing heat generation from ferromagnetic particles under an ac magnetic field. We immobilize α-amylase on the surface of ferromagnetic particles and analyze its activity. We find that when α-amylase/ferromagnetic particle hybrids, that is, ferromagnetic particles, on which α-amylase molecules are immobilized, are subjected to an ac magnetic field, the particles generate heat and as a result, α-amylase on the particles is heated up and activated. We next prepare a solution, in which α-amylase/ferromagnetic particle hybrids and free, nonimmobilized chitinase are dispersed, and analyze their activities. We find that when the solution is subjected to an ac magnetic field, the activity of α-amylase immobilized on the particles increases, whereas that of free chitinase hardly changes; in other words, only α-amylase immobilized on the particles is selectively activated due to heat generation from the particles.

  15. Study on VCSEL laser heating chip in nuclear magnetic resonance gyroscope

    Science.gov (United States)

    Liang, Xiaoyang; Zhou, Binquan; Wu, Wenfeng; Jia, Yuchen; Wang, Jing

    2017-10-01

    In recent years, atomic gyroscope has become an important direction of inertial navigation. Nuclear magnetic resonance gyroscope has a stronger advantage in the miniaturization of the size. In atomic gyroscope, the lasers are indispensable devices which has an important effect on the improvement of the gyroscope performance. The frequency stability of the VCSEL lasers requires high precision control of temperature. However, the heating current of the laser will definitely bring in the magnetic field, and the sensitive device, alkali vapor cell, is very sensitive to the magnetic field, so that the metal pattern of the heating chip should be designed ingeniously to eliminate the magnetic field introduced by the heating current. In this paper, a heating chip was fabricated by MEMS process, i.e. depositing platinum on semiconductor substrates. Platinum has long been considered as a good resistance material used for measuring temperature The VCSEL laser chip is fixed in the center of the heating chip. The thermometer resistor measures the temperature of the heating chip, which can be considered as the same temperature of the VCSEL laser chip, by turning the temperature signal into voltage signal. The FPGA chip is used as a micro controller, and combined with PID control algorithm constitute a closed loop control circuit. The voltage applied to the heating resistor wire is modified to achieve the temperature control of the VCSEL laser. In this way, the laser frequency can be controlled stably and easily. Ultimately, the temperature stability can be achieved better than 100mK.

  16. Fundamental relations of mineral specific magnetic carriers for paleointensity determination

    Czech Academy of Sciences Publication Activity Database

    Kletetschka, Günther; Wieczorek, M. A.

    2017-01-01

    Roč. 272, November 2017 (2017), s. 44-49 ISSN 0031-9201 Institutional support: RVO:67985831 Keywords : Paleofield determination * TRM * Planetary magnetic anomalies * Néel’s theory of magnetism * Magnetic acquisition * Moon * Mars Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics OBOR OECD: Particles and field physics Impact factor: 2.075, year: 2016

  17. Heating water. Specifications for feedwater; Heizungswasser. Eine Standortbestimmung

    Energy Technology Data Exchange (ETDEWEB)

    Hannemann, M. [Hannemann Wassertechnik (Germany)

    2004-08-01

    Water is indispensable for life and for engineering. It is so universal that we seem to have lost respect for it. In heating systems, it is recommended to know about its technical properties and to account for them by appropriate measures. (orig.) [German] Wasser ist fuer Leben und Technik unverzichtbar. Vielleicht ist es auf die enormen Vorkommen und die Selbstverstaendlichkeit der Nutzung zurueckzufuehren, dass wir ein Stueck Achtung vor diesem Gut verloren haben. Wer bei der technischen Verwendung als Waermetraeger in Heizungsanlagen die speziellen Eigenschaften und die Wechselwirkungen mit Werkstoffen missachtet, kann schnell in unruhiges Fahrwasser geraten, mithin bis zum Schiffbruch. Wer die Wechselwirkungen kennt, beachtet und mit speziellen Behandlungsverfahren gegensteuert, ist daher gut beraten. (orig.)

  18. Specific heat of parabolic quantum dot with Dresselhaus spin-orbit interaction

    Energy Technology Data Exchange (ETDEWEB)

    Sanjeev Kumar, D., E-mail: sanjeevchs@gmail.com; Chatterjee, Ashok [School of Physics, University of Hyderabad, Hyderabad, India - 500046 (India); Mukhopadhyay, Soma [DVR College of Engineering & Technology, Kashipur, Medak, India - 502285 (India)

    2016-04-13

    The heat capacity of a two electron quantum dot with parabolic confinement in magnetic field in the presence of electron-electron interaction, Dresselhaus spin-orbit interaction (DSOI) has been studied. The electron-electron interaction has been treated by a model potential which makes the Hamiltonian to be soluble exactly. The RSOI has been treated by a unitary transformation and the terms up to second order in DSOI constants have been considered. The heat capacity is obtained by canonical averaging. So far no study has been reported in literature on the effect of DSOI on the heat capacity of quantum dot.

  19. Determination of the thermal conductivity and specific heat capacity of neem seeds by inverse problem method

    Directory of Open Access Journals (Sweden)

    S.N. Nnamchi

    2010-01-01

    Full Text Available Determination of the thermal conductivity and the specific heat capacity of neem seeds (Azadirachta indica A. Juss usingthe inverse method is the main subject of this work. One-dimensional formulation of heat conduction problem in a spherewas used. Finite difference method was adopted for the solution of the heat conduction problem. The thermal conductivityand the specific heat capacity were determined by least square method in conjunction with Levenberg-Marquardt algorithm.The results obtained compare favourably with those obtained experimentally. These results are useful in the analysis ofneem seeds drying and leaching processes.

  20. The effect of heat treatments on Ni43Mn42Co4Sn11 meta-magnetic shape memory alloys for magnetic refrigeration

    International Nuclear Information System (INIS)

    Bruno, Nickolaus M.; Yegin, Cengiz; Karaman, Ibrahim; Chen, Jing-Han; Ross, Joseph H.; Liu, Jian; Li, Jianguo

    2014-01-01

    The inverse magnetocaloric effect (MCE) in bulk polycrystalline and melt-spun ribbons of the Ni 43 Mn 42 Co 4 Sn 11 meta-magnetic shape memory alloy (MSMA) is investigated. The influence of several material properties on the MCE and relative cooling power (RCP) are discussed and the property combinations for optimum MCE and RCP identified for a given thermodynamic framework. These include a small slope of magnetic field vs. martensitic transformation temperature phase diagram, a narrow transformation range, low transformation thermal hysteresis and a large change in magnetization on martensitic transformation, which results in low levels of applied magnetic fields desired for repeated MCE on field cycling. The thermo-magnetic responses of the samples were measured before and after heat treatments. The heat-treated ribbons produced the most favorable MCE by exhibiting the highest magnetization change and smallest elastic energy storage through the transformation. This was attributed to the specific microstructural features, including grain size to thickness ratio and degree of L2 1 ordering. In addition, issues in the literature in determining RCP for MSMAs are discussed, and a new method to find RCP is proposed and implemented. Completely reversible magnetic-field-induced martensitic transformation cycles were used to investigate hysteresis losses relative to actual refrigeration cycles, whereby the RCP was calculated using the defined thermodynamic framework and indirectly measured entropy changes. The annealed ribbons exhibited the high RCP level of 242 J kg −1 under the applied field of 7 T compared with a theoretical maximum of 343 J kg −1 . Similar values of RCP in other MSMAs can be achievable if microstructural elastic energy storage and hysteresis loss are minimized during the transformation with the help of annealing treatments

  1. Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

    International Nuclear Information System (INIS)

    Rack, Michael Thomas

    2014-01-01

    Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

  2. Influence of resonant magnetic perturbations on transient heat load deposition and fast ion losses

    Energy Technology Data Exchange (ETDEWEB)

    Rack, Michael Thomas

    2014-07-11

    Thermonuclear fusion is the energy conversion process which keeps the sun shining. For the last six decades, researchers have been investigating the physics involved in order to enable the usage of this energy supply on Earth. The most promising candidates for fusion power plants are based on magnetic confinement of plasma to provide the ideal conditions for efficient thermonuclear fusion in well controlled surroundings. One important aspect is the control of instabilities that occur in the edge region of the plasma and lead to an ejection of huge amounts of energy. Magnetic perturbation fields which are resonant in the plasma edge are found to modify the plasma favourably and reduce the impact of these instabilities. This dissertation focuses on the effects of resonant magnetic perturbation fields on the ejected energy as well as on the drawbacks of these perturbation fields. The transient energy ejection which is triggered by the instabilities causes extreme heat loads on the wall components in fusion devices. Therefore, it is crucial to understand how resonant magnetic perturbation fields affect the heat load deposition. Furthermore, the impact of resonant magnetic perturbation fields on the confinement of fast ions is an important aspect as fast ions are still required to be well confined in order to avoid additional wall loads and increase the fusion efficiency. Recent upgrades on the Joint European Torus allow for a detailed study of the heat load deposition profiles caused by transient events. Throughout this work, the new features are used for the study of the modifications of the transient heat load depositions that occur if resonant magnetic perturbation fields are applied. This leads to a further understanding of the processes involved during the plasma edge instabilities. Additionally, an alternative method using lower hybrid waves for applying resonant magnetic perturbations is investigated. Furthermore, a new diagnostic, capable of detecting fast ion

  3. Flow of magnetic particles in blood with isothermal heating: A fractional model for two-phase flow

    Science.gov (United States)

    Ali, Farhad; Imtiaz, Anees; Khan, Ilyas; Sheikh, Nadeem Ahmad

    2018-06-01

    In the sixteenth century, medical specialists were of the conclusion that magnet can be utilized for the treatment or wipe out the illnesses from the body. On this basis, the research on magnet advances day by day for the treatment of different types of diseases in mankind. This study aims to investigate the effect of magnetic field and their applications in human body specifically in blood. Blood is a non-Newtonian fluid because its viscosity depends strongly on the fraction of volume occupied by red cells also called the hematocrit. Therefore, in this paper blood is considered as an example of non-Newtonian Casson fluid. The blood flow is considered in a vertical cylinder together with heat transfer due to mixed conviction caused by buoyancy force and the external pressure gradient. Effect of magnetic field on the velocities of blood and magnetic particles is also considered. The problem is modelled using the Caputo-Fabrizio derivative approach. The governing fractional partial differential equations are solved using Laplace and Hankel transformation techniques and exact solutions are obtained. Effects of different parameters such as Grashof number, Prandtl number, Casson fluid parameter and fractional parameters, and magnetic field are shown graphically. Both velocity profiles increase with the increase of Grashoff number and Casson fluid parameter and reduce with the increase of magnetic field.

  4. Natural convection and boiling heat transfer of a liquid metal in a magnetic field

    International Nuclear Information System (INIS)

    Seki, Masahiro; Kawamura, Hiroshi

    1983-02-01

    A liquid metal is often assumed as a coolant and a breeding material of a Tokamak fusion reactor. However, many problems on the thermo-hydraulics of a liquid metal in a magnetic field are still remained to be studied. In the present report, natural convection and boiling of a liquid metal in a strong magnetic field are studied to examine a fundamental feasibility of a fusion reactor cooled by a liquid metal. In the experimental study of the natural convection, the circulation of a liquid metal was found to be surpressed even by a magnetic field parallel to the gravity. A numerical study has confirmed the conclusion drawn by the experiment. In the study of boiling heat transfer, stable boiling of a liquid metal has been found also in a strong magnetic field. The burnout heat flux hardly affected by the magnetic field. These indicate a fundamental feasibility of the liquid-metal cooling for a Tokamak fusion reactor. (author)

  5. Flat super-oscillatory lens for heat-assisted magnetic recording with sub-50 nm resolution.

    Science.gov (United States)

    Yuan, Guanghui; Rogers, Edward T F; Roy, Tapashree; Shen, Zexiang; Zheludev, Nikolay I

    2014-03-24

    Heat-assisted magnetic recording (HAMR) is a future roadmap technology to overcome the superparamagnetic limit in high density magnetic recording. Existing HAMR schemes depend on a simultaneous magnetic stimulation and light-induced local heating of the information carrier. To achieve high-density recorded data, near-field plasmonic transducers have been proposed as light concentrators. Here we suggest and investigate in detail an alternative approach exploiting a far-field focusing device that can focus light into sub-50 nm hot-spots in the magnetic recording layer using a laser source operating at 473 nm. It is based on a recently introduced super-oscillatory flat lens improved with the use of solid immersion, giving an effective numerical aperture as high as 4.17. The proposed solution is robust and easy to integrate with the magnetic recording head thus offering a competitive advantage over plasmonic technology.

  6. The change of magnetic properties of minerals and rocks after their microwave heating

    Directory of Open Access Journals (Sweden)

    Brianèin Jaroslav

    2002-03-01

    Full Text Available The possibility of microwaves utilisation in drying processes of different materials (e.g. wood, textiles, coffee, paper, treating of synthetics, glass and ceramic materials, vulcanisation of gum, melting of ferrous and non-ferrous ores, intensification processes of disintegration of raw materials, desulphurization of coal as well as in processes of disposing hazardous wastes is studied. The presented paper describes the influence of microwave radiation on on the change of magnetic properties of minerals and ores. The modification of magnetic properties of valuable components of irradiated ores increases the efficiency of process of their magnetic separation. Changes of magnetic properties of samples were evaluated by measuring the magnetic susceptibility and by X-ray diffraction analysis before and after their microwave heating.Thermal pretreatment of weakly magnetic ores by applying of microwave radiation is tested on the samples of iron spathic ore from the Rudòany deposit (25.1 % of Fe, 5.1 % of SiO2 and the Nižná Slaná ore (31.1 % of Fe, 9.6 % of SiO2. The influence of microwave on a rate of change of iron spathic ore to magnetite depending on the time of heating was observed for a grain size of 0.5 – 1 mm at a constant oven output of 900 W. The weight of tested samples was 100 g. After 10 min. of heating, an essential change of magnetic properties of ore samples from both deposits occurs and after 15 min. a rapid growth of magnetic susceptibility value is observed. This fact testifies about an intensive decomposition of siderite. The achieved values of magnetic susceptibility, results of chemical analyses as well as the X-ray diffraction records of irradiated samples confirmed the formation of new strongly magnetic mineral phases. Finally, after 40 min. of heating, a sintering of grains resulting in agglomerates, accompanied by molten mass creation, were observed.

  7. Determination of Specific Heat Capacity on Composite Shape-Stabilized Phase Change Materials and Asphalt Mixtures by Heat Exchange System.

    Science.gov (United States)

    Ma, Biao; Zhou, Xue-Yan; Liu, Jiang; You, Zhanping; Wei, Kun; Huang, Xiao-Feng

    2016-05-19

    Previous research has shown that composite shape-stabilized phase change material (CPCM) has a remarkable capacity for thermal storage and stabilization, and it can be directly applied to highway construction without leakage. However, recent studies on temperature changing behaviors of CPCM and asphalt mixture cannot intuitively reflect the thermoregulation mechanism and efficiency of CPCM on asphalt mixture. The objective of this paper is to determine the specific heat capacity of CPCM and asphalt mixtures mixed with CPCM using the heat exchange system and the data acquisition system. Studies have shown that the temperature-rise curve of 5 °C CPCM has an obvious temperature plateau, while an asphalt mixture mixed with 5 °C CPCM does not; with increasing temperature, the specific heat capacities of both 5 °C CPCM and asphalt mixture first increase and then decrease, while the variation rate of 5 °C CPCM is larger than that of the asphalt mixture, and the maximum specific heat capacity of 5 °C CPCM appears around the initial phase change temperature. It is concluded that the temperature intervals of 5 °C CPCM are -18 °C-7 °C, 7 °C-25 °C and 25 °C-44 °C, respectively, and that of the asphalt mixture are -18 °C~10 °C, -10 °C~5 °C and 5 °C~28 °C. A low dosage of 5 °C CPCM has little influence on the specific heat capacity of asphalt mixture. Finally, the functions of specific heat capacities and temperature for CPCM and asphalt mixture mixed with CPCM were recommended by the sectional regression method.

  8. Optimal laser heating of plasmas confined in strong solenoidal magnetic fields

    International Nuclear Information System (INIS)

    Vitela, J.; Akcasu, A.Z.

    1987-01-01

    Optimal Control Theory is used to analyze the laser-heating of plasmas confined in strong solenoidal magnetic fields. Heating strategies that minimize a linear combination of heating time and total energy spent by the laser system are found. A numerical example is used to illustrate the theory. Results of this example show that by an appropriate modulation of the laser intensity, significant savings in the laser energy are possible with only slight increases in the heating time. However, results may depend strongly on the initial state of the plasma and on the final ion temperature. (orig.)

  9. Origin of two maxima in specific heat in enthalpy relaxation under thermal history composed of cooling, annealing, and heating.

    Science.gov (United States)

    Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

    2016-12-01

    The origin of two maxima in specific heat observed at the higher and the lower temperatures in the glass-transition region in the heating process has been studied for polymethyl methacrylate and polyvinyl chloride using differential scanning calorimetry, and the calculation was done using the phenomenological model equation under a thermal history of the typical annealing experiment composed of cooling, annealing, and heating. The higher maximum is observed above the glass-transition temperature, and it remains almost unchanged independent of annealing time t_{a}, while the lower one is observed above an annealing temperature T_{a} and shifts toward the higher one, increasing its magnitude with t_{a}. The analysis by the phenomenological model equation proposed in order to interpret the memory effect in the glassy state clarifies that under a typical annealing history, two maxima in specific heat essentially appear. The shift of the lower maximum toward higher temperatures from above T_{a} is caused by an increase in the amount of relaxation during annealing with t_{a}. The annealing temperature and the amount of relaxation during annealing play a major role in the determination of the number of maxima in the specific heat.

  10. Multi-band description of the specific heat and thermodynamic critical field in MgB2 superconductor

    Science.gov (United States)

    Szcześniak, R.; Jarosik, M. W.; Tarasewicz, P.; Durajski, A. P.

    2018-05-01

    The thermodynamic properties of MgB2 superconductor can be explained using the multi-band models. In the present paper we have examined the experimental data available in literature and we have found out that it is possible to reproduce the measured values of the superconducting energy gaps, the thermodynamic critical magnetic field and specific heat jump within the framework of two-band Eliashberg formalism and appropriate defined free energy difference between superconducting and normal state. Moreover, we found that the obtained results differ significantly from the predictions of the conventional Bardeen-Cooper-Schrieffer theory.

  11. Thermal fluctuations in the classical superconductor Nb{sub 3}Sn from high-resolution specific-heat measurements

    Energy Technology Data Exchange (ETDEWEB)

    Lortz, Rolf [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland)], E-mail: Rolf.Lortz@physics.unige.ch; Wang Yuxing; Junod, Alain [Department of Condensed Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva 4 (Switzerland); Toyota, Naoki [Physics Department, Graduate School of Science, Tohoku University, 980-8571 Sendai (Japan)

    2007-09-01

    The range of thermal fluctuations in 'classical' bulk superconductors is extremely small and especially in low-fields hardly experimentally accessible. With a new type of calorimeter we were able to detect a tiny lambda anomaly in the specific-heat of the superconductor Nb{sub 3}Sn within a narrow temperature range around the H{sub c2} line. We show that the evolution of the anomaly as a function of magnetic field follows scaling laws expected in the presence of critical thermal fluctuations.

  12. Measurement and Model Validation of Nanofluid Specific Heat Capacity with Differential Scanning Calorimetry

    Directory of Open Access Journals (Sweden)

    Harry O'Hanley

    2012-01-01

    Full Text Available Nanofluids are being considered for heat transfer applications; therefore it is important to know their thermophysical properties accurately. In this paper we focused on nanofluid specific heat capacity. Currently, there exist two models to predict a nanofluid specific heat capacity as a function of nanoparticle concentration and material. Model I is a straight volume-weighted average; Model II is based on the assumption of thermal equilibrium between the particles and the surrounding fluid. These two models give significantly different predictions for a given system. Using differential scanning calorimetry (DSC, a robust experimental methodology for measuring the heat capacity of fluids, the specific heat capacities of water-based silica, alumina, and copper oxide nanofluids were measured. Nanoparticle concentrations were varied between 5 wt% and 50 wt%. Test results were found to be in excellent agreement with Model II, while the predictions of Model I deviated very significantly from the data. Therefore, Model II is recommended for nanofluids.

  13. Cylinder pressure, performance parameters, heat release, specific heats ratio and duration of combustion for spark ignition engine

    International Nuclear Information System (INIS)

    Shehata, M.S.

    2010-01-01

    An experimental work were conducted for investigating cylinder pressure, performance parameters, heat release, specific heat ratio and duration of combustion for multi cylinder spark ignition engine (SIE). Ccylinder pressure was measured for gasoline, kerosene and Liquefied Petroleum Gases (LPG) separately as a fuel for SIE. Fast Fourier Transformations (FFT) was used to cylinder pressure data transform from time domain into frequency domain to develop empirical correlation for calculating cylinder pressures at different engine speeds and different fuels. In addition, Inverse Fast Fourier Transformations (IFFT) was used to cylinder pressure reconstruct into time domain. The results gave good agreement between the measured cylinder pressure and the reconstructed cylinder pressure in time domain with different engine speeds and different fuels. The measured cylinder pressure and hydraulic dynamotor were the sours of data for calculating engine performance parameters. First law of thermodynamics and single zone heat release model with temperature dependant specific heat ratio γ(T) were the main tools for calculating heat release and heat transfer to cylinder walls. Third order empirical correlation for calculating γ(T) was one of the main gains of the present study. The correlation gave good agreement with other researchers with wide temperatures range. For kerosene, cylinder pressure is higher than for gasoline and LPG due to high volumetric efficiency where kerosene density (mass/volume ratio) is higher than gasoline and LPG. In addition, kerosene heating value is higher than gasoline that contributes in heat release rate and pressure increases. Duration of combustion for different engine speeds was determined using four different methods: (I) Mass fuel burnt, (II) Entropy change, (III) Temperature dependant specific heat ratio γ(T), and (IV) Logarithmic scale of (P and V). The duration of combustion for kerosene is smaller than for gasoline and LPG due to high

  14. Cylinder pressure, performance parameters, heat release, specific heats ratio and duration of combustion for spark ignition engine

    Energy Technology Data Exchange (ETDEWEB)

    Shehata, M.S. [Mechanical Engineering Technology Department, Higher Institute of Technology, Banha University, 4Zagalol Street, Benha, Galubia 1235 Z (Egypt)

    2010-12-15

    An experimental work were conducted for investigating cylinder pressure, performance parameters, heat release, specific heat ratio and duration of combustion for multi cylinder spark ignition engine (SIE). Ccylinder pressure was measured for gasoline, kerosene and Liquefied Petroleum Gases (LPG) separately as a fuel for SIE. Fast Fourier Transformations (FFT) was used to cylinder pressure data transform from time domain into frequency domain to develop empirical correlation for calculating cylinder pressures at different engine speeds and different fuels. In addition, Inverse Fast Fourier Transformations (IFFT) was used to cylinder pressure reconstruct into time domain. The results gave good agreement between the measured cylinder pressure and the reconstructed cylinder pressure in time domain with different engine speeds and different fuels. The measured cylinder pressure and hydraulic dynamotor were the source of data for calculating engine performance parameters. First law of thermodynamics and single zone heat release model with temperature dependant specific heat ratio {gamma}(T) were the main tools for calculating heat release and heat transfer to cylinder walls. Third order empirical correlation for calculating {gamma}(T) was one of the main gains of the present study. The correlation gave good agreement with other researchers with wide temperatures range. For kerosene, cylinder pressure is higher than for gasoline and LPG due to high volumetric efficiency where kerosene density (mass/volume ratio) is higher than gasoline and LPG. In addition, kerosene heating value is higher than gasoline that contributes in heat release rate and pressure increases. Duration of combustion for different engine speeds was determined using four different methods: (I) Mass fuel burnt, (II) Entropy change, (III) Temperature dependant specific heat ratio {gamma}(T), and (IV) Logarithmic scale of (P and V). The duration of combustion for kerosene is smaller than for gasoline and

  15. Theoretical study of the magnetic heat capacity of praseodymium metal

    International Nuclear Information System (INIS)

    Glenn, R.L.

    1976-01-01

    The heat capacity of praseodymium metal at low temperatures is calculated using a valence change model. The effect of the presence of a small temperature-dependent and field-dependent percentage of 4+ ions is computed using crystalfield techniques. Good agreement with the experimentally determined values is obtained for polycrystalline and single-crystal praseodymium in zero field and various other fields up to 30 koe. In addition, the effects of selected exchange models on the heat capacity and susceptibility are computed. The model is shown to be compatible with both the parallel and perpendicular susceptibilities

  16. Detection of magnetic-labeled antibody specific recognition events by combined atomic force and magnetic force microscopy

    International Nuclear Information System (INIS)

    Hong Xia; Liu Yanmei; Li Jun; Guo Wei; Bai Yubai

    2009-01-01

    Atomic force (AFM) and magnetic force microscopy (MFM) were developed to detect biomolecular specific interaction. Goat anti-mouse immunoglobulin (anti-IgG) was covalently attached onto gold substrate modified by a self-assembly monolayer of thioctic acid via 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide (EDC) activation. Magnetic-labeled IgG then specifically adsorbed onto anti-IgG surface. The morphological variation was identified by AFM. MFM was proved to be a fine assistant tool to distinguish the immunorecognized nanocomposites from the impurities by detection of the magnetic signal from magnetic-labeled IgG. It would enhance the understanding of biomolecular recognition process.

  17. Detection of magnetic-labeled antibody specific recognition events by combined atomic force and magnetic force microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hong Xia [Center for Advanced Optoelectronic Functional Materials Research, Key Laboratory of UV Light-Emitting Materials and Technology, Ministry of Education, Northeast Normal University, Changchun 130024 (China); College of Chemistry, Jilin University, Changchun 130023 (China)], E-mail: xiahong@nenu.edu.cn; Liu Yanmei; Li Jun; Guo Wei; Bai Yubai [College of Chemistry, Jilin University, Changchun 130023 (China)

    2009-09-15

    Atomic force (AFM) and magnetic force microscopy (MFM) were developed to detect biomolecular specific interaction. Goat anti-mouse immunoglobulin (anti-IgG) was covalently attached onto gold substrate modified by a self-assembly monolayer of thioctic acid via 1-ethyl-3-[3-(dimethylamino) propyl] carbodiimide (EDC) activation. Magnetic-labeled IgG then specifically adsorbed onto anti-IgG surface. The morphological variation was identified by AFM. MFM was proved to be a fine assistant tool to distinguish the immunorecognized nanocomposites from the impurities by detection of the magnetic signal from magnetic-labeled IgG. It would enhance the understanding of biomolecular recognition process.

  18. An analysis of boundary-effects in obtaining the frequency dependent specific heat by effusivity measurements

    DEFF Research Database (Denmark)

    Christensen, Tage Emil; Behrens, Claus

    The frequency dependent specific heat is a significant response function characterizing the glass transition. Contrary to the dielectric response it is not easily measured over many decades. The introduction of the 3-omega method, where the temperature oscillations at a planar oscillatoric heat g...

  19. Demonstration of Efficient Core Heating of Magnetized Fast Ignition in FIREX project

    Science.gov (United States)

    Johzaki, Tomoyuki

    2017-10-01

    Extensive theoretical and experimental research in the FIREX ``I project over the past decade revealed that the large angular divergence of the laser generated electron beam is one of the most critical problems inhibiting efficient core heating in electron-driven fast ignition. To solve this problem, beam guiding using externally applied kilo-tesla class magnetic field was proposed, and its feasibility has recently been numerically demonstrated. In 2016, integrated experiments at ILE Osaka University demonstrated core heating efficiencies reaching > 5 % and heated core temperatures of 1.7 keV. In these experiments, a kilo-tesla class magnetic field was applied to a cone-attached Cu(II) oleate spherical solid target by using a laser-driven capacitor-coil. The target was then imploded by G-XII laser and heated by the PW-class LFEX laser. The heating efficiency was evaluated by measuring the number of Cu-K- α photons emitted. The heated core temperature was estimated by the X-ray intensity ratio of Cu Li-like and He-like emission lines. To understand the detailed dynamics of the core heating process, we carried out integrated simulations using the FI3 code system. Effects of magnetic fields on the implosion and electron beam transport, detailed core heating dynamics, and the resultant heating efficiency and core temperature will be presented. I will also discuss the prospect for an ignition-scale design of magnetized fast ignition using a solid ball target. This work is partially supported by JSPA KAKENHI Grant Number JP16H02245, JP26400532, JP15K21767, JP26400532, JP16K05638 and is performed with the support and the auspices of the NIFS Collaboration Research program (NIFS12KUGK057, NIFS15KUGK087).

  20. Pressure dependence of thermal conductivity and specific heat in CeRh2Si2 measured by an extended thermal relaxation method

    Science.gov (United States)

    Nishigori, Shijo; Seida, Osamu

    2018-05-01

    We have developed a new technique for measuring thermal conductivity and specific heat under pressure by improving a thermal relaxation method. In this technique, a cylindrical sample with a small disc heater is embedded in the pressure-transmitting medium, then temperature variations of the sample and heater were directly measured by thermocouples during a heating and cooling process. Thermal conductivity and specific heat are estimated by comparing the experimental data with temperature variations simulated by a finite element method. The obtained thermal conductivity and specific heat of the test sample CeRh2Si2 exhibit a small enhancement and a clear peak arising from antiferromagnetic transition, respectively. The observation of these typical behaviors for magnetic compounds indicate that the technique is valid for the study on thermal properties under pressure.

  1. Blockage effects on viscous fluid flow and heat transfer past a magnetic obstacle in a duct

    International Nuclear Information System (INIS)

    Zhang Xi-Dong; Huang Hu-Lin

    2013-01-01

    The effect of lateral walls on fluid flow and heat transfer is investigated when a fluid passes a magnetic obstacle. The blockage ratio β that represents the ratio between the width of external magnet M y and the spanwise width L y is employed to depict the effect. The finite volume method (FVM) based on the PISO algorithm is applied for the blockage ratios of 0.2, 0.3, and 0.4. The results show that the value of Strouhal number St increases as the blockage ratio β increases, and for small β, the variation of St is very small when the interaction parameter and Reynolds number are increasing. Moreover, the cross-stream mixing induced by the magnetic obstacle can enhance the wall-heat transfer and the maximum value of the overall heat transfer increment is about 50.5%

  2. Heat transfer from aluminum to He II: application to superconductive magnetic energy storage

    International Nuclear Information System (INIS)

    Van Sciver, S.W.; Boom, R.W.

    1979-01-01

    Heat transfer problems associated with large scale Superconductive Magnetic Energy Storage (SMES) are unique due to the proposed size of a unit. The Wisconsin design consists of a cryogenically stable magnet cooled with He II at 1.8 K. The special properties of He II (T 2 at 1.91 K and a recovery at 0.7 W/cm 2 . The advantages of operating the magnet under subcooled conditions are exemplified by improved heat transfer. The maximum at 1.89 K and 1.3 atm pressure is 2.3 W/cm 2 with recovery enhanced to 1.9 W/cm 2 . A conservative maximum heat flux of 0.5 W/cm 2 with an associated temperature difference of 0.5 K has been chosen for design. Elements of the experimental study as well as the design will be discussed

  3. Specific heat measurements of CePt{sub 3}Si and Ce{sub 1+x}Pt{sub 3+y}Si{sub 1+z}

    Energy Technology Data Exchange (ETDEWEB)

    Motoyama, G. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan)]. E-mail: motoyama@sci.u-hyogo.ac.jp; Watanabe, M. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Maeda, K. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Oda, Y. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Ueda, K. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan); Kohara, T. [Graduate School of Material Science, University of Hyogo, Kamigori-cho, Ako-gun, Hyogo 678-1297 (Japan)

    2007-03-15

    We have measured the specific heat of a series of polycrystalline CePt{sub 3}Si and Ce{sub 1+x}Pt{sub 3+y}Si{sub 1+z} samples whose compositions vary slightly from the stoichiometric composition. We observed two peaks derived from magnetic anomalies on the specific heat measurements of the Ce{sub 1+x}Pt{sub 3+y}Si{sub 1+z} samples. One of the peaks relates to the antiferromagnetic phase transition at T{sub N}=2.2K. The other is a large peak at 2.7K observed for the sample that showed a ferromagnetic anomaly at 3.0K on the temperature dependence of the magnetization. Heat treatment had different effects between these anomalies.

  4. Magnetic nanoparticles with high specific absorption rate of electromagnetic energy at low field strength for hyperthermia therapy

    Science.gov (United States)

    Shubitidze, Fridon; Kekalo, Katsiaryna; Stigliano, Robert; Baker, Ian

    2015-03-01

    Magnetic nanoparticles (MNPs), referred to as the Dartmouth MNPs, which exhibit high specific absorption rate at low applied field strength have been developed for hyperthermia therapy applications. The MNPs consist of small (2-5 nm) single crystals of gamma-Fe2O3 with saccharide chains implanted in their crystalline structure, forming 20-40 nm flower-like aggregates with a hydrodynamic diameter of 110-120 nm. The MNPs form stable (>12 months) colloidal solutions in water and exhibit no hysteresis under an applied quasistatic magnetic field, and produce a significant amount of heat at field strengths as low as 100 Oe at 99-164 kHz. The MNP heating mechanisms under an alternating magnetic field (AMF) are discussed and analyzed quantitatively based on (a) the calculated multi-scale MNP interactions obtained using a three dimensional numerical model called the method of auxiliary sources, (b) measured MNP frequency spectra, and (c) quantified MNP friction losses based on magneto-viscous theory. The frequency responses and hysteresis curves of the Dartmouth MNPs are measured and compared to the modeled data. The specific absorption rate of the particles is measured at various AMF strengths and frequencies, and compared to commercially available MNPs. The comparisons demonstrate the superior heating properties of the Dartmouth MNPs at low field strengths (therapy to deeper tumors that were previously non-viable targets, potentially enabling the treatment of some of the most difficult cancers, such as pancreatic and rectal cancers, without damaging normal tissue.

  5. Low-temperature specific heat of the degenerate supersymmetric t-J model in one dimension

    International Nuclear Information System (INIS)

    Lee, K.; Schlottmann, P.

    1996-01-01

    We consider the one-dimensional SU(N)-invariant t-J model, which consists of electrons with N spin components on a lattice with nearest-neighbor hopping t constrained by the excluded multiple occupancy of the sites and spin-exchange J between neighboring lattice sites. The model is integrable and has been diagonalized in terms of nested Bethe ansatze at the supersymmetric point t=J. The low-T specific heat is proportional to T. The γ-coefficient is extracted from the thermodynamic Bethe-ansatz equations and is expressed in terms of the spin wave velocities and the group velocity of the charges for arbitrary N, band filling, and splitting of the levels (magnetic and crystalline fields). Our results contain the following special cases: (i) For N=2 the traditional spin-1/2 supersymmetric t-J model, (ii) for exactly one electron per site the SU(N)-Heisenberg chain, and (iii) for N=4 the two-band supersymmetric t-J model with crystalline field splitting. copyright 1996 American Institute of Physics

  6. Specific absorption rate dependence on temperature in magnetic field hyperthermia measured by dynamic hysteresis losses (ac magnetometry)

    Science.gov (United States)

    Garaio, Eneko; Sandre, Olivier; Collantes, Juan-Mari; Garcia, Jose Angel; Mornet, Stéphane; Plazaola, Fernando

    2015-01-01

    Magnetic nanoparticles (NPs) are intensively studied for their potential use for magnetic hyperthermia, a treatment that has passed a phase II clinical trial against severe brain cancer (glioblastoma) at the end of 2011. Their heating power, characterized by the ‘specific absorption rate (SAR)’, is often considered temperature independent in the literature, mainly because of the difficulties that arise from the measurement methodology. Using a dynamic magnetometer presented in a recent paper, we measure here the thermal dependence of SAR for superparamagnetic iron oxide (maghemite) NPs of four different size-ranges corresponding to mean diameters around 12 nm, 14 nm, 15 nm and 16 nm. The article reports a parametrical study extending from 10 to 60 {}^\\circ C in temperature, from 75 to 1031 kHz in frequency, and from 2 to 24 kA m-1 in magnetic field strength. It was observed that SAR values of smaller NPs decrease with temperature whereas for the larger sample (16 nm) SAR values increase with temperature. The measured variation of SAR with temperature is frequency dependent. This behaviour is fully explained within the scope of linear response theory based on Néel and Brown relaxation processes, using independent magnetic measurements of the specific magnetization and the magnetic anisotropy constant. A good quantitative agreement between experimental values and theoretical values is confirmed in a tri-dimensional space that uses as coordinates the field strength, the frequency and the temperature.

  7. Technical specifications for the provision of heat and steam sources for INPP and Visaginas. Final report

    International Nuclear Information System (INIS)

    2003-01-01

    In October 1999, the National Energy Strategy was approved by the Lithuanian Parliament. The National Energy Strategy included the decision to close Unit-1 of INPP before 2005. Later is has been decided to close Unit 2 before the end of 2009 as well. The closure and decommissioning will have heavy impact on the heat supply for the city of Visaginas. Unit 1 and Unit 2 of INPP supplies hot water and steam to INPP for process purposes and for space heating of residential and commercial buildings. When Unit 1 is permanently shut down, reliable heat and steam sources independent of the power plants own heat and steam generation facilities are required for safety reasons in the event of shutdown of the remaining unit for maintenance or in an emergency. These steam and heat sources must be operational before single unit operation is envisaged. Provision of a reliable independent heat and steam source is therefore urgent. After both reactors are shut down permanently, a steam source will be needed at the plant for radioactive waste storage and disposal. INPP and DEA has performed a feasibility study for the provision of a reliable heat source for Ignalina Nuclear Power Plant and Visaginas, and the modernisation of Visaginas district heating system. The objective of this project is to prepare technical specifications for the provision of new heat and steam sources for INPP and Visaginas, and for rehabilitation of the heat transmission pipeline between INPP, the back-up boiler station and Visaginas City. The results of the study are presented in detail in the reports and technical specifications: 1. Transient analysis for Visaginas DH system, 2. Non-destructive testing of boiler stations, pump stations and transmission lines, 3. Conceptual design, 4. Technical specifications, Package 1 to 6. The study has suggested: 1. Construction of new steam boiler station, 2. Construction of new heat only boiler station, 3. Renovation of existing back-up heat only boiler station, 4

  8. Effects of coating molecules on the magnetic heating properties of Au-Fe3O4 heterodimer nanoparticles

    Science.gov (United States)

    Yamamoto, Y.; Ogasawara, J.; Himukai, H.; Itoh, T.

    2016-10-01

    In this paper, we report the heating properties of gold-magnetite (Au-Fe3O4) heterodimer nanoparticles (NPs) subjected to an alternating magnetic field. The Au-Fe3O4 NPs coated with oleic acid and oleylamine (OA) were synthesized through a method that combines seed mediation and high-temperature decomposition. The coating was replaced with dimercaptosuccinic acid (DMSA) by the ligand-exchange method. The specific absorption rates (SARs) for the OA- and DMSA-coated Au-Fe3O4 NPs coated with OA and DMSA at room temperature were determined through the calorimetric and magnetometric methods. SAR depended on the square of the magnetic field H up to an H value of 4 kA/m. The absolute value of the SAR for DMSA-coated NPs is about fivefold higher than that of the OA-coated NPs. The AC magnetic hysteresis measurements showed the recovery of the magnetic volume and the decrease in the magnetic anisotropy of the DMSA-coated NPs relative to those of the OA-coated NPs. These results suggest that the protective agent influences the magnetic properties of magnetite NPs via gold NPs.

  9. Heat and momentum transfer for magnetoconvection in a vertical external magnetic field

    Science.gov (United States)

    Zürner, Till; Liu, Wenjun; Krasnov, Dmitry; Schumacher, Jörg

    2016-11-01

    The scaling theory of Grossmann and Lohse for the turbulent heat and momentum transfer is extended to the magnetoconvection case in the presence of a (strong) vertical magnetic field. The comparison with existing laboratory experiments and direct numerical simulations in the quasistatic limit allows to restrict the parameter space to very low Prandtl and magnetic Prandtl numbers and thus to reduce the number of unknown parameters in the model. Also included is the Chandrasekhar limit for which the outer magnetic induction field B is large enough such that convective motion is suppressed and heat is transported by diffusion. Our theory identifies four distinct regimes of magnetoconvection which are distinguished by the strength of the outer magnetic field and the level of turbulence in the flow, respectively. LIMTECH Research Alliance and Research Training Group GK 1567 on Lorentz Force Velocimetry, funded by the Deutsche Forschungsgemeinschaft.

  10. Heat characteristic analysis of a conduction cooling toroidal-type SMES magnet

    International Nuclear Information System (INIS)

    Kim, K.M.; Kim, A.R.; Kim, J.G.; Kim, D.W.; Park, M.; Yu, I.K.; Eom, B.Y.; Sim, K.; Kim, S.H.; Shon, M.H.; Kim, H.J.; Bae, H.J.; Seong, K.C.

    2010-01-01

    This paper analyzed the heat characteristics of a conduction cooling toroidal-type SMES magnet. The authors designed and manufactured a conduction cooling toroidal-type SMES magnet which consists of 30 double pancake coils. One (a single pancake coil) of a double pancake coil is arranged at an angle of 6 o from each other. The shape of the toroidal-type SMES magnet was designed by a 3D CAD program. The heat invasion was investigated under no-load condition and the thermal characteristic of the toroidal-type SMES magnet was analyzed using the Finite Elements Method program. Both the analyzed and the experiment results are compared and discussed in detail.

  11. Stability and fast heat removal with He-II cooling for pulsed superconductive magnets

    International Nuclear Information System (INIS)

    Desportes, H.

    1979-01-01

    The use of pressurized superfluid helium between 1.6 K and 1.8 K is being considered for a number of superconducting magnet applications. This type of cooling is particularly interesting in the case of pulsed field magnets where large heat fluxes need to be evacuated in a short time. This paper reviews a few recent experiments on heat transport properties and stability in He-II, which contribute to evaluating its potential use for such an application. Present technology is illustrated by the description of a large test facility recently operated at Saclay

  12. EFFECT OF HORIZONTALLY INHOMOGENEOUS HEATING ON FLOW AND MAGNETIC FIELD IN THE CHROMOSPHERE OF THE SUN

    Energy Technology Data Exchange (ETDEWEB)

    Song, P.; Vasyliūnas, V. M., E-mail: paul_song@uml.edu [Space Science Laboratory and Department of Physics, University of Massachusetts Lowell, Lowell, MA 01854 (United States)

    2014-12-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models.

  13. EFFECT OF HORIZONTALLY INHOMOGENEOUS HEATING ON FLOW AND MAGNETIC FIELD IN THE CHROMOSPHERE OF THE SUN

    International Nuclear Information System (INIS)

    Song, P.; Vasyliūnas, V. M.

    2014-01-01

    The solar chromosphere is heated by damped Alfvén waves propagating upward from the photosphere at a rate that depends on magnetic field strength, producing enhanced heating at low altitudes in the extended weak-field regions (where the additional heating accounts for the radiative losses) between the boundaries of the chromospheric network as well as enhanced heating per particle at higher altitudes in strong magnetic field regions of the network. The resulting inhomogeneous radiation and temperature distribution produces bulk flows, which in turn affect the configuration of the magnetic field. The basic flow pattern is circulation on the spatial scale of a supergranule, with upward flow in the strong-field region; this is a mirror image in the upper chromosphere of photospheric/subphotospheric convection widely associated with the formation of the strong network field. There are significant differences between the neutral and the ionized components of the weakly ionized medium: neutral flow streamlines can form closed cells, whereas plasma is largely constrained to flow along the magnetic field. Stresses associated with this differential flow may explain why the canopy/funnel structures of the network magnetic field have a greater horizontal extent and are relatively more homogeneous at high altitudes than is expected from simple current-free models

  14. Magnetic flux tubes and transport of heat in the convection zone of the sun

    International Nuclear Information System (INIS)

    Spruit, H.C.

    1977-01-01

    This thesis consists of five papers dealing with transport of heat in the solar convection zone on the one hand, and with the structure of magnetic flux tubes in the top of the convection zone on the other hand. These subjects are interrelated. For example, the heat flow in the convection zone is disturbed by the presence of magnetic flux tubes, while exchange of heat between a flux tube and the convection zone is important for the energy balance of such a tube. A major part of this thesis deals with the structure of small magnetic flux tubes. Such small tubes (diameters less than about 2'') carry most of the flux appearing at the solar surface. An attempt is made to construct models of the surface layers of such small tubes in sufficient detail to make a comparison with observations possible. Underlying these model calculations is the assumption that the magnetic elements at the solar surface are flux tubes in a roughly static equilibrium. The structure of such tubes is governed by their pressure equilibrium, exchange of heat with the surroundings, and transport of heat by some modified form of convection along the tube. The tube models calculated are compared with observations

  15. Parametric investigation of heating due to magnetic fluid hyperthermia in a tumor with blood perfusion

    Energy Technology Data Exchange (ETDEWEB)

    Liangruksa, Monrudee [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States); Ganguly, Ranjan [Department of Power Engineering, Jadavpur University, Kolkata 700098 (India); Puri, Ishwar K., E-mail: ikpuri@vt.ed [Department of Engineering Science and Mechanics, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061 (United States)

    2011-03-15

    Magnetic fluid hyperthermia (MFH) is a cancer treatment that can selectively elevate the tumor temperature without significantly damaging the surrounding healthy tissue. Optimal MFH design requires a fundamental parametric investigation of the heating of soft materials by magnetic fluids. We model the problem of a spherical tumor and its surrounding healthy tissue that are heated by exciting a homogeneous dispersion of magnetic nanoparticles infused only into the tumor with an external AC magnetic field. The key dimensionless parameters influencing thermotherapy are the Peclet, Fourier, and Joule numbers. Analytical solutions for transient and steady hyperthermia provide correlations between these parameters and the portions of tumor and healthy tissue that are subjected to a threshold temperature beyond which they are damaged. Increasing the ratio of the Fourier and Joule numbers also increases the tumor temperature, but doing so can damage the healthy tissue. Higher magnetic heating is required for larger Peclet numbers due to the larger convection heat loss that occurs through blood perfusion. A comparison of the model predictions with previous experimental data for MFH applied to rabbit tumors shows good agreement. The optimal MFH conditions are identified based on two indices, the fraction I{sub T} of the tumor volume in which the local temperature is above a threshold temperature and the ratio I{sub N} of the damaged normal tissue volume to the tumor tissue volume that also lies above it. The spatial variation in the nanoparticle concentration is also considered. A Gaussian distribution provides efficacy while minimizing the possibility of generating a tumor hot spot. Varying the thermal properties of tumor and normal tissue alters I{sub T}and I{sub N} but the nature of the temperature distribution remains unchanged. - Research highlights: > Analytical model of magnetic fluid hyperthermia of tumor tissue perfused with magnetic nanoparticles that is surrounded

  16. Parametric investigation of heating due to magnetic fluid hyperthermia in a tumor with blood perfusion

    International Nuclear Information System (INIS)

    Liangruksa, Monrudee; Ganguly, Ranjan; Puri, Ishwar K.

    2011-01-01

    Magnetic fluid hyperthermia (MFH) is a cancer treatment that can selectively elevate the tumor temperature without significantly damaging the surrounding healthy tissue. Optimal MFH design requires a fundamental parametric investigation of the heating of soft materials by magnetic fluids. We model the problem of a spherical tumor and its surrounding healthy tissue that are heated by exciting a homogeneous dispersion of magnetic nanoparticles infused only into the tumor with an external AC magnetic field. The key dimensionless parameters influencing thermotherapy are the Peclet, Fourier, and Joule numbers. Analytical solutions for transient and steady hyperthermia provide correlations between these parameters and the portions of tumor and healthy tissue that are subjected to a threshold temperature beyond which they are damaged. Increasing the ratio of the Fourier and Joule numbers also increases the tumor temperature, but doing so can damage the healthy tissue. Higher magnetic heating is required for larger Peclet numbers due to the larger convection heat loss that occurs through blood perfusion. A comparison of the model predictions with previous experimental data for MFH applied to rabbit tumors shows good agreement. The optimal MFH conditions are identified based on two indices, the fraction I T of the tumor volume in which the local temperature is above a threshold temperature and the ratio I N of the damaged normal tissue volume to the tumor tissue volume that also lies above it. The spatial variation in the nanoparticle concentration is also considered. A Gaussian distribution provides efficacy while minimizing the possibility of generating a tumor hot spot. Varying the thermal properties of tumor and normal tissue alters I T and I N but the nature of the temperature distribution remains unchanged. - Research Highlights: →Analytical model of magnetic fluid hyperthermia of tumor tissue perfused with magnetic nanoparticles that is surrounded by healthy tissue

  17. MAGNETIC END CLOSURES FOR PLASMA CONFINING AND HEATING DEVICES

    Science.gov (United States)

    Post, R.F.

    1963-08-20

    More effective magnetic closure field regions for various open-ended containment magnetic fields used in fusion reactor devices are provided by several spaced, coaxially-aligned solenoids utilized to produce a series of nodal field regions of uniform or, preferably, of incrementally increasing intensity separated by lower intensity regions outwardly from the ends of said containment zone. Plasma sources may also be provided to inject plasma into said lower intensity areas to increase plasma density therein. Plasma may then be transported, by plasma diffusion mechanisms provided by the nodal fields, into the containment field. With correlated plasma densities and nodal field spacings approximating the mean free partl cle collision path length in the zones between the nodal fields, optimum closure effectiveness is obtained. (AEC)

  18. Unsteady free convection MHD flow between two heated vertical parallel plates in induced magnetic field

    International Nuclear Information System (INIS)

    Chakraborty, S.; Borkakati, A.K.

    1999-01-01

    An unsteady viscous incompressible free convection flow of an electrically conducting fluid between two heated vertical parallel plates is considered in presence of a uniform magnetic field applied transversely to the flow. The approximate analytical solutions for velocity, induced field and temperature distributions are obtained for small and large magnetic Reynolds number. The skin-friction on the two plates are obtained and plotted graphically. The problem is extended for thermometric case. (author)

  19. Stabilization of a magnetic island by localized heating in a tokamak with stiff temperature profile

    Science.gov (United States)

    Maget, Patrick; Widmer, Fabien; Février, Olivier; Garbet, Xavier; Lütjens, Hinrich

    2018-02-01

    In tokamaks plasmas, turbulent transport is triggered above a threshold in the temperature gradient and leads to stiff profiles. This particularity, neglected so far in the problem of magnetic island stabilization by a localized heat source, is investigated analytically in this paper. We show that the efficiency of the stabilization is deeply modified compared to the previous estimates due to the strong dependence of the turbulence level on the additional heat source amplitude inside the island.

  20. Measurements of thermal diffusivity, specific heat capacity and thermal conductivity with LFA 447 apparatus

    DEFF Research Database (Denmark)

    Zajas, Jan Jakub; Heiselberg, Per

    The LFA 447 can be successfully used for measurements of thermal diffusivity, specific heat and thermal conductivity of various samples. It is especially useful when determining the properties of materials on a very small scale. The matrix measurement mode allows for determining the local...... that the heat losses from both samples during the measurement are similar. Finally, the leveling of the samples is very important. Very small discrepancies can cause a massive error in the derivation of specific heat capacity and, as a result, thermal conductivity....

  1. Heat-Assisted Magnetic Recording: Fundamental Limits to Inverse Electromagnetic Design

    Science.gov (United States)

    Bhargava, Samarth

    In this dissertation, we address the burgeoning fields of diffractive optics, metals-optics and plasmonics, and computational inverse problems in the engineering design of electromagnetic structures. We focus on the application of the optical nano-focusing system that will enable Heat-Assisted Magnetic Recording (HAMR), a higher density magnetic recording technology that will fulfill the exploding worldwide demand of digital data storage. The heart of HAMR is a system that focuses light to a nano- sub-diffraction-limit spot with an extremely high power density via an optical antenna. We approach this engineering problem by first discussing the fundamental limits of nano-focusing and the material limits for metal-optics and plasmonics. Then, we use efficient gradient-based optimization algorithms to computationally design shapes of 3D nanostructures that outperform human designs on the basis of mass-market product requirements. In 2014, the world manufactured ˜1 zettabyte (ZB), ie. 1 Billion terabytes (TBs), of data storage devices, including ˜560 million magnetic hard disk drives (HDDs). Global demand of storage will likely increase by 10x in the next 5-10 years, and manufacturing capacity cannot keep up with demand alone. We discuss the state-of-art HDD and why industry invented Heat-Assisted Magnetic Recording (HAMR) to overcome the data density limitations. HAMR leverages the temperature sensitivity of magnets, in which the coercivity suddenly and non-linearly falls at the Curie temperature. Data recording to high-density hard disks can be achieved by locally heating one bit of information while co-applying a magnetic field. The heating can be achieved by focusing 100 microW of light to a 30nm diameter spot on the hard disk. This is an enormous light intensity, roughly ˜100,000,000x the intensity of sunlight on the earth's surface! This power density is ˜1,000x the output of gold-coated tapered optical fibers used in Near-field Scanning Optical Microscopes

  2. Heat transfer enhancement of Fe{sub 3}O{sub 4} ferrofluids in the presence of magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Fadaei, Farzad; Shahrokhi, Mohammad; Molaei Dehkordi, Asghar, E-mail: amolaeid@sharif.edu; Abbasi, Zeinab

    2017-05-01

    In this article, three-dimensional (3D) forced-convection heat transfer of magnetic nanofluids in a pipe subject to constant wall heat flux in the presence of single or double permanent magnet(s) or current-carrying wire has been investigated and compared. In this regard, laminar fluid flow and equilibrium magnetization for the ferrofluid were considered. In addition, variations of magnetic field in different media were taken into account and the assumption of having a linear relationship of magnetization with applied magnetic field intensity was also relaxed. Effects of magnetic field intensity, nanoparticle volume fraction, Reynolds number value, and the type of magnetic field source (i.e., a permanent magnet or current-carrying wire) on the forced-convection heat transfer of magnetic nanofluids were carefully investigated. It was found that by applying the magnetic field, the fluid mixing could be intensified that leads to an increase in the Nusselt number value along the pipe length. Moreover, the obtained simulation results indicate that applying the magnetic field induced by two permanent magnets with a magnetization of 3×10{sup 5} (A/m) (for each one), the fully developed Nusselt number value can be increased by 196%. - Highlights: • 3D forced-convection heat transfer of magnetic nanofluids is investigated. • Effects of single or double permanent magnet on the heat transfer are studied. • Influences of magnetic field induced by a current-carrying wire are studied. • Effects of magnetic field intensity and Reynolds number value are studied. • Variations of magnetic field in different media are taken into account.

  3. Modelling of Quench Limit for Steady State Heat Deposits in LHC Magnets

    CERN Document Server

    Bocian, D; Siemko, A

    2008-01-01

    A quench, the transition of a conductor from the superconducting to the normal conducting state, occurs irreversibly in the accelerator magnets if one of the three parameters: temperature, magnetic field or current density exceeds a critical value. Energy deposited in the superconductor by the particle beams provokes quenches detrimental for the accelerator operation. In particular if particles impacting on the vacuum chamber and their secondary showers depose energy in the magnet coils. The Large Hadron Collider (LHC) nominal beam intensity is 3.2 ldr 10^14 protons. A quench occurs if a fraction of the order of 10^7 protons per second is lost locally. A network model is used to simulate the thermodynamic behaviour of the magnets. The heat flow in the network model was validated with measurements performed in the CERN magnet test facility. A steady state heat flow was introduced in the coil by using the quench heaters implemented in the LHC magnets. The value of the heat source current is determined by the ne...

  4. Buoyancy effects in vertical rectangular duct with coplanar magnetic field and single sided heat load

    Science.gov (United States)

    Kostichev, P. I.; Poddubnyi, I. I.; Razuvanov, N. G.

    2017-11-01

    In some DEMO blanket designs liquid metal flows in vertical ducts of rectangular cross-section between ceramic breeder units providing their cooling. Heat exchange in these conditions is governed by the influence of magnetic field (coplanar) and by buoyancy effects that depend on the flow orientation to the gravity vector (downward and upward flow). Magnetohydrodynamic and heat transfer of liquid metal in vertical rectangular ducts is not well researched. Experimental study of buoyancy effects in rectangular duct with coplanar magnetic field for one-sided heat load and downward and upward flowsis presented in this paper. The detail research with has been done on mercury MHD close loop with using of the probe technique allow to discover several advantageous and disadvantageous effects. The intensive impact of buoyancy force has been observed in a few regime of downward flow which has been laminarized by magnetic field. Due to the development in the flow of the secondary large-scale vortices heat transfer improved and the temperature fluctuations of the abnormally high intensity have been fixed. On the contrary, in the upward flow the buoyancy force stabilized the flow which lead to decreasing of the turbulence heat transfer ratio and, consequently, deterioration of heat transfer.

  5. Experimental Investigation on the Specific Heat of Carbonized Phenolic Resin-Based Ablative Materials

    Science.gov (United States)

    Zhao, Te; Ye, Hong; Zhang, Lisong; Cai, Qilin

    2017-10-01

    As typical phenolic resin-based ablative materials, the high silica/phenolic and carbon/phenolic composites are widely used in aerospace field. The specific heat of the carbonized ablators after ablation is an important thermophysical parameter in the process of heat transfer, but it is rarely reported. In this investigation, the carbonized samples of the high silica/phenolic and carbon/phenolic were obtained through carbonization experiments, and the specific heat of the carbonized samples was determined by a 3D DSC from 150 °C to 970 °C. Structural and compositional characterizations were performed to determine the mass fractions of the fiber and the carbonized product of phenolic which are the two constituents of the carbonized samples, while the specific heat of each constituent was also measured by 3D DSC. The masses of the carbonized samples were reduced when heated to a high temperature in the specific heat measurements, due to the thermal degradation of the carbonized product of phenolic resin in the carbonized samples. The raw experimental specific heat of the two carbonized samples and the carbonized product of phenolic resin was modified according to the quality changes of the carbonized samples presented by TGA results. Based on the mass fraction and the specific heat of each constituent, a weighted average method was adopted to obtain the calculated results of the carbonized samples. Due to the unconsolidated property of the fiber samples which impacts the reliability of the DSC measurement, there is a certain deviation between the experimental and calculated results of the carbonized samples. Considering the similarity of composition and structure, the data of quartz glass and graphite were used to substitute the specific heat of the high silica fiber and carbon fiber, respectively, resulting in better agreements with the experimental ones. Furthermore, the accurate specific heat of the high silica fiber and carbon fiber bundles was obtained by

  6. HEATING MECHANISMS IN THE LOW SOLAR ATMOSPHERE THROUGH MAGNETIC RECONNECTION IN CURRENT SHEETS

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Lei; Lin, Jun [Yunnan Observatories, Chinese Academy of Sciences, Kunming 650011 (China); Roussev, Ilia I. [Division of Geosciences, National Science Foundation Arlington, Virginia (United States); Schmieder, Brigitte, E-mail: leini@ynao.ac.cn [Observatoire de Paris, LESIA, Meudon (France)

    2016-12-01

    We simulate several magnetic reconnection processes in the low solar chromosphere/photosphere; the radiation cooling, heat conduction and ambipolar diffusion are all included. Our numerical results indicate that both the high temperature (≳8 × 10{sup 4} K) and low temperature (∼10{sup 4} K) magnetic reconnection events can happen in the low solar atmosphere (100–600 km above the solar surface). The plasma β controlled by plasma density and magnetic fields is one important factor to decide how much the plasma can be heated up. The low temperature event is formed in a high β magnetic reconnection process, Joule heating is the main mechanism to heat plasma and the maximum temperature increase is only several thousand Kelvin. The high temperature explosions can be generated in a low β magnetic reconnection process, slow and fast-mode shocks attached at the edges of the well developed plasmoids are the main physical mechanisms to heat the plasma from several thousand Kelvin to over 8 × 10{sup 4} K. Gravity in the low chromosphere can strongly hinder the plasmoid instability and the formation of slow-mode shocks in a vertical current sheet. Only small secondary islands are formed; these islands, however, are not as well developed as those in the horizontal current sheets. This work can be applied to understand the heating mechanism in the low solar atmosphere and could possibly be extended to explain the formation of common low temperature Ellerman bombs (∼10{sup 4} K) and the high temperature Interface Region Imaging Spectrograph (IRIS) bombs (≳8 × 10{sup 4}) in the future.

  7. Interplanetary magnetic field orientations associated with bidirectional electron heat fluxes detected at ISEE 3

    International Nuclear Information System (INIS)

    Stansberry, J.A.; Gosling, J.T.; Thomsen, M.F.; Bame, S.J.; Smith, E.J.

    1988-01-01

    A statistical survey of interplanetary magnetic field orientations associated with bidirectional electron heat fluxes observed at ISEE 3 in orbit about the Sunward Lagrange point indicates that magnetic connection of the spacecraft to the Earth's bow shock was frequently the source of the bidirectionality. When the interplanetary magnetic field was oriented within 5 0 of the Earth-spacecraft line, backstreaming electrons from the bow shock were clearly observed approximately 18% of the time, and connections apparently occurred for angles as large as ∼30 0 --35 0 . copyright American Geophysical Union 1988

  8. Thermal conductance of heat transfer interfaces for conductively cooled superconducting magnets

    International Nuclear Information System (INIS)

    Cooper, T.L.; Walters, J.D.; Fikse, T.H.

    1996-01-01

    Minimizing thermal resistances across interfaces is critical for efficient thermal performance of conductively cooled superconducting magnet systems. Thermal conductance measurements have been made for a flexible thermal coupling, designed to accommodate magnet-to-cryocooler and cryocooler-to-shield relative motion, and an interface incorporating Multilam designed as a sliding thermal connector for cryocoolers. Temperature changes were measured across each interface as a function of heat input. Thermal conductances have been calculated for each interface, and the impact of each interface on conductively cooled magnet systems will be discussed

  9. Stress-induced heating in commercial conductors and its possible influence on magnet performance

    International Nuclear Information System (INIS)

    Easton, D.S.; Kroeger, D.M.; Moazed, A.

    1976-01-01

    Calorimetric measurements show that significant amounts of heat are generated when a multifilamentary composite conductor is stressed in tension to levels expected to occur in large, high-field magnet systems. When the stress on the conductor is repetitively cycled between zero and some maximum value, the amount of heat produced per cycle is constant after the first few cycles. Comparison is made between calorimetric determinations of heat injections and the work done on the specimen as indicated by stress-strain curves. Stress-strain curves for a number of commercial conductors indicate that the most important determinant of the magnitude of this effect is the choice of matrix material

  10. Local entropy generation analysis of a rotary magnetic heat pump regenerator

    International Nuclear Information System (INIS)

    Drost, M.K.; White, M.D.

    1990-01-01

    The rotary magnetic heat pump has attractive thermodynamic performance but it is strongly influenced by the effectiveness of the regenerator. This paper uses local entropy generation analysis to evaluate the regenerator design and to suggest design improvements. The results show that performance of the proposed design is dominated by heat transfer related entropy generation. This suggests that enhancement concepts that improve heat transfer should be considered, even if the enhancement causes a significant increase in viscous losses (pressure drop). One enhancement technique, the use of flow disruptors, was evaluated and the results showed that flow disruptors can significantly reduce thermodynamic losses

  11. Numerical Simulation of the Moving Induction Heating Process with Magnetic Flux Concentrator

    Directory of Open Access Journals (Sweden)

    Feng Li

    2013-01-01

    Full Text Available The induction heating with ferromagnetic metal powder bonded magnetic flux concentrator (MPB-MFC demonstrates more advantages in surface heating treatments of metal. However, the moving heating application is mostly applied in the industrial production. Therefore, the analytical understanding of the mechanism, efficiency, and controllability of the moving induction heating process becomes necessary for process design and optimization. This paper studies the mechanism of the moving induction heating with magnetic flux concentrator. The MPB-MFC assisted moving induction heating for Inconel 718 alloy is studied by establishing the finite element simulation model. The temperature field distribution is analyzed, and the factors influencing the temperature are studied. The conclusion demonstrates that the velocity of the workpiece should be controlled properly and the heat transfer coefficient (HTC has little impact on the temperature development, compared with other input parameters. In addition, the validity of the static numerical model is verified by comparing the finite element simulation with experimental results on AISI 1045 steel. The numerical model established in this work can provide comprehensive understanding for the process control in production.

  12. Bulk ion acceleration and particle heating during magnetic reconnection in a laboratory plasma

    Energy Technology Data Exchange (ETDEWEB)

    Yoo, Jongsoo; Yamada, Masaaki; Ji, Hantao; Jara-Almonte, Jonathan; Myers, Clayton E. [Center for Magnetic Self-Organization, Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

    2014-05-15

    Bulk ion acceleration and particle heating during magnetic reconnection are studied in the collisionless plasma of the Magnetic Reconnection Experiment (MRX). The plasma is in the two-fluid regime, where the motion of the ions is decoupled from that of the electrons within the ion diffusion region. The reconnection process studied here is quasi-symmetric since plasma parameters such as the magnitude of the reconnecting magnetic field, the plasma density, and temperature are compatible on each side of the current sheet. Our experimental data show that the in-plane (Hall) electric field plays a key role in ion heating and acceleration. The electrostatic potential that produces the in-plane electric field is established by electrons that are accelerated near the electron diffusion region. The in-plane profile of this electrostatic potential shows a “well” structure along the direction normal to the reconnection current sheet. This well becomes deeper and wider downstream as its boundary expands along the separatrices where the in-plane electric field is strongest. Since the in-plane electric field is 3–4 times larger than the out-of-plane reconnection electric field, it is the primary source of energy for the unmagnetized ions. With regard to ion acceleration, the Hall electric field causes ions near separatrices to be ballistically accelerated toward the outflow direction. Ion heating occurs as the accelerated ions travel into the high pressure downstream region. This downstream ion heating cannot be explained by classical, unmagnetized transport theory; instead, we conclude that ions are heated by re-magnetization of ions in the reconnection exhaust and collisions. Two-dimensional (2-D) simulations with the global geometry similar to MRX demonstrate downstream ion thermalization by the above mechanisms. Electrons are also significantly heated during reconnection. The electron temperature sharply increases across the separatrices and peaks just outside of the

  13. An Induction Heating Method with Traveling Magnetic Field for Long Structure Metal

    Science.gov (United States)

    Sekine, Takamitsu; Tomita, Hideo; Obata, Shuji; Saito, Yukio

    A novel dismantlable adhesion method for recycling operation of interior materials is proposed. This method is applied a high frequency induction heating and a thermoplastic adhesive. For an adhesion of interior material to long steel stud, a conventional spiral coil as like IH cooking heater gives inadequateness for uniform heating to the stud. Therefore, we have proposed an induction heating method with traveling magnetic field for perfect long structures bonding. In this paper, we describe on the new adhesion method using the 20kHz, three-phase 200V inverter and linear induction coil. From induction heating characteristics to thin steel plates and long studs, the method is cleared the usefulness for uniform heating to long structures.

  14. The effect of magnetic field on instabilities of heat transfer from an obstacle in a channel

    International Nuclear Information System (INIS)

    Rashidi, S.; Esfahani, J.A.

    2015-01-01

    This paper presents forced convective heat transfer in a channel with a built-in square obstacle. The governing equations with the boundary conditions are solved using a finite volume method. The computations were done for a fixed blockage ratio (S=1/8) at Pr=0.71, and Reynolds (Re) and Stuart (N) numbers ranging from 1 to 250 and 0 to 10, respectively. The results are presented to show the effect of the channel walls and streamwise magnetic field at different Reynolds numbers on forced convection heat transfer from a square cylinder. A correlation is obtained for Nusselt number, in which the effect of a magnetic field is taken into account. The obtained results revealed that the existence of channel walls decreases the effects of magnetic field on Nusselt number. It also showed that by increasing Stuart number the thickness of thermal boundary layer increases and the convective heat transfer decreases. - Highlights: • The magnetic field is used to control the instabilities of heat transfer. • The thickness of thermal boundary layer increases by increasing Stuart number. • Unsteadiness in temperature field increases with increase in Reynolds number. • Time-averaged Nusselt number decreases with increase in Stuart number. • The Lorentz forces are much denser near the surface of the obstacle

  15. On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

    NARCIS (Netherlands)

    Kenjeres, S.

    2016-01-01

    In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and

  16. Numerical and Experimental Investigation of Heat Flow in Permanent Magnet Brushless DC Hub Motor

    DEFF Research Database (Denmark)

    Fasil, Muhammed; Plesner, Daniel; Walther, Jens Honore

    2014-01-01

    This paper investigates the heat dissipation in the hub motor of an electric two-wheeler using lumped parameter (LP), finite element (FE) and computational fluid dynamic (CFD) models. The motor uses external rotor permanent magnet brushless DC topology and nearly all of its losses are generated...

  17. Transient heat transfer analysis of superconducting magnetic levitating flywheel rotor operating in vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Mochida, A.; Kudo, K.; Higasa, H.

    1999-07-01

    In the present study, transient temperature rise is analyzed in a flywheel type power storage system operated in vacuum environment. The flywheel rotor is levitated by high-temperature-superconducting magnetic bearing to reduce the bearing loss. Though the superconductor is cooled by liquid nitrogen, the temperature of the whole system rises due to Joule heating in the coils of the bearings and the motor during the operation. If the temperature should reach the critical temperature of the permanent magnet used for the magnetic bearings after long time operation, the magnetic bearings lose their effect. The heat generated in the levitated rotor diffuses within it by heat conduction and finally emitted to its surrounding solid materials by thermal radiation from the rotor surfaces across vacuum layer. Numerical simulation is carried out calculating the transient radiative-conductive heat transfer and time-dependent profiles of temperature within the rotor are obtained. The results are compared with the experimentally obtained temperatures by measured a test model of 1kWh power storage and the measured profiles of the temperature rise of the rotor fit very well with the calculated ones. Using this simulation tool, the effects of the surface emissivity of the materials of the rotor and the stator, the temperature of the surrounding casings and the thermal conductivity of the materials on the temperature profiles in the system are estimated.

  18. Hyperthermia with rotating magnetic nanowires inducing heat into tumor by fluid friction

    Energy Technology Data Exchange (ETDEWEB)

    Egolf, Peter W.; Pawlowski, Anne-Gabrielle; Tsague, Paulin; Marco, Bastien de; Bovy, William; Tucev, Sinisa [Institute of Thermal Sciences and Engineering, University of Applied Sciences of Western Switzerland, CH 1401 Yverdon-les-Bains (Switzerland); Shamsudhin, Naveen, E-mail: snaveen@ethz.ch; Pané, Salvador; Pokki, Juho; Ansari, M. H. D.; Nelson, Bradley J. [Multi-Scale Robotics Lab, Institute of Robotics and Intelligent Systems, ETH Zurich, CH 8092 Zurich (Switzerland); Vuarnoz, Didier [Ecole Polytechnique Fédérale de Lausanne (EPFL), EPFL Fribourg, CH 1701 Fribourg (Switzerland)

    2016-08-14

    A magnetic hyperthermia cancer treatment strategy that does not operate by means of conventional heating mechanisms is presented. The proposed approach consists of injecting a gel with homogeneously distributed magnetic nanowires into a tumor. Upon the application of a low-frequency rotating or circularly polarized magnetic field, nanowires spin around their center of viscous drag due to torque generated by shape anisotropy. As a result of external rotational forcing and fluid friction in the nanoparticle's boundary layer, heating occurs. The nanowire dynamics is theoretically and experimentally investigated, and different feasibility proofs of the principle by physical modeling, which adhere to medical guidelines, are presented. The magnetic nanorotors exhibit rotations and oscillations with quite a steady center of gravity, which proves an immobile behavior and guarantees a time-independent homogeneity of the spatial particle distribution in the tumor. Furthermore, a fluid dynamic and thermodynamic heating model is briefly introduced. This model is a generalization of Penne's model that for this method reveals theoretic heating rates that are sufficiently high, and fits well into medical limits defined by present standards.

  19. Performance-oriented Analysis of a Hybrid magnetic Assembly for a Heat-pump Magnetocaloric Device

    DEFF Research Database (Denmark)

    Insinga, Andrea Roberto; Smith, Anders; Bahl, Christian R.H.

    2014-01-01

    Conventional active-regenerator magnetocaloric devices include moving parts, with the purpose of generating an oscillating magnetic field in the magneto-caloric material, placed inside the regenerator. In this work a different design is analyzed, for application in a magnetocaloric heat pump...

  20. Specific heat of the chiral-soliton-lattice phase in Yb(Ni0.94Cu0.06)3Al9

    Science.gov (United States)

    Ninomiya, Hiroki; Sato, Takaaki; Inoue, Katsuya; Ohara, Shigeo

    2018-05-01

    We have studied the monoaxial-chiral helimagnet YbNi3Al9 and its-substituted analogue Yb(Ni0.94Cu0.06)3Al9. These compounds belong to a chiral space group R32. In Yb(Ni0.94Cu0.06)3Al9 with the magnetic ordering temperature TM = 6.4 K , only when the magnetic field is applied perpendicular to the helical axis, the chiral soliton lattice is observed below Hc = 10 kOe . YbNi3Al9 with TM = 3.4 K exhibits a metamagnetic transition at Hc = 1 kOe in 2 K. To study the formation of chiral helimagnetic state and chiral soliton lattice, we have measured the specific heat in magnetic fields applied parallel and perpendicular to the helical axis. In zero field, with decreasing temperature, specific heat shows λ-type phase transition from paramagnetic state to chiral helimagnetic one. At the temperature where the chiral soliton lattice emerges, we have found that the specific heat shows a sharp peak. In addition, at around the crossover between paramagnetic state and forced-ferromagnetic one, a broad maximum has been observed. We have determined the magnetic phase diagrams of YbNi3Al9 and Yb(Ni0.94Cu0.06)3Al9.

  1. Specification of steam generator, condenser and regenerative heat exchanger materials for nuclear applications

    International Nuclear Information System (INIS)

    Jovasevic, J.V.; Stefanovic, V.M.; Spasic, Z.LJ.

    1977-01-01

    The basic standards specifications of materials for nuclear applications are selected. Seamless Ni-Cr-Fe alloy Tubes (Inconel-600) for steam generators, condensers and other heat exchangers can be employed instead of austenitic stainless steal or copper alloys tubes; supplementary requirements for these materials are given. Specifications of Ni-Cr-Fe alloy plate, sheet and strip for steam generator lower sub-assembly, U-bend seamless copper-alloy tubes for heat exchanger and condensers are also presented. At the end, steam generator channel head material is proposed in the specification for carbon-steel castings suitable for welding

  2. Unsteady Magnetized Flow and Heat Transfer of a Viscoelastic fluid over a Stretching Surface

    Science.gov (United States)

    Ghosh, Sushil Kumar

    2017-12-01

    This paper is to study the flow of heated ferro-fluid over a stretching sheet under the influence of magnetic field. The fluid considered in the present investigation is a mixture of blood as well as fluid-dispersed magnetic nano particles and under this context blood is found to be the appropriate choice of viscoelastic, Walter's B fluid. The objective of the present work is to study the effect of various parameters found in the mathematical analysis. Taking into account the blood has zero electrical conductivity, magnetization effect has been considered in the governing equation of the present study with the use of ferro-fluid dynamics principle. By introducing appropriate non-dimensional variables into the governing equations of unsteady two-dimensional flow of viscoelastic fluid with heat transfer are converted to a set of ordinary differential equations with appropriate boundary conditions. Newton's linearization technique has been employed for the solution of non-linear ordinary differential equations. Important results found in the present investigation are the substantial influence of ferro-magnetic parameter, Prandlt number and the parameter associated with the thermal conductivity on the flow and heat transfer. It is observed that the presence of magnetic dipole essentially reduces the flow velocity in the vertical direction and that helps to damage the cancer cells in the tumor region.

  3. Coronal heating driven by a magnetic gradient pumping mechanism in solar plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Tan, Baolin, E-mail: bltan@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories of Chinese Academy of Sciences, Beijing 100012 (China)

    2014-11-10

    The heating of the solar corona is a longstanding mystery in astrophysics. Considering that the solar magnetic field is spatially inhomogeneous with a considerable magnetic gradient from the solar surface to the corona, this work proposes a magnetic gradient pumping (MGP) mechanism to try to explain the formation of hot plasma upflows, such as hot type II spicules and hot plasma ejections. In the MGP mechanism, the magnetic gradient may drive the energetic particles to move upward from the underlying solar atmosphere and form hot upflows. These upflow energetic particles are deposited in the corona, causing it to become very hot. Rough estimations indicate that the solar corona can be heated to above 1 million degrees, and the upflow velocity is about 40 km s{sup –1} in the chromosphere and about 130 km s{sup –1} in the corona. The solar magnetic flux tubes act as pumpers to extract energetic particles from the underlying thermal photosphere, convey them, and deposit them in the corona. The deposit of these energetic particles causes the corona to become hot, and the escape of such particles from the photosphere leaves it a bit cold. This mechanism can present a natural explanation to the mystery of solar coronal heating.

  4. Magnetic pumping as a source of particle heating in the solar wind

    Science.gov (United States)

    Lichko, E. R.; Egedal, J.; Daughton, W. S.; Kasper, J. C.

    2017-12-01

    Magnetic pumping is a means of heating plasmas for both fusion and astrophysical applications. In this study a magnetic pumping model is developed as a possible explanation for the heating and the generation of power-law distribution functions observed in the solar wind plasma. In most previous studies turbulent energy is only dissipated at microscopic kinetic scales. In contrast, magnetic pumping energizes the particles through the largest scale turbulent fluctuations, thus bypassing the energy cascade. Kinetic simulations are applied to verify these analytic predictions. Previous results for the one-dimensional model, as well as initial results for a two-dimensional model which includes the effects of trapped and passing particles are presented. Preliminary results of the presence of this mechanism in the bow shock region, using spacecraft data from the Magnetospheric Multiscale mission, are presented as well.

  5. Study and Development of an Air Conditioning System Operating on a Magnetic Heat Pump Cycle

    Science.gov (United States)

    Wang, Pao-Lien

    1991-01-01

    This report describes the design of a laboratory scale demonstration prototype of an air conditioning system operating on a magnetic heat pump cycle. Design parameters were selected through studies performed by a Kennedy Space Center (KSC) System Simulation Computer Model. The heat pump consists of a rotor turning through four magnetic fields that are created by permanent magnets. Gadolinium was selected as the working material for this demonstration prototype. The rotor was designed to be constructed of flat parallel disks of gadolinium with very little space in between. The rotor rotates in an aluminum housing. The laboratory scale demonstration prototype is designed to provide a theoretical Carnot Cycle efficiency of 62 percent and a Coefficient of Performance of 16.55.

  6. A practical nonlocal model for heat transport in magnetized laser plasmas

    International Nuclear Information System (INIS)

    Nicolaie, Ph.D.; Feugeas, J.-L.A.; Schurtz, G.P.

    2006-01-01

    A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaie, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case

  7. A practical nonlocal model for heat transport in magnetized laser plasmas

    Science.gov (United States)

    Nicolaï, Ph. D.; Feugeas, J.-L. A.; Schurtz, G. P.

    2006-03-01

    A model of nonlocal transport for multidimensional radiation magnetohydrodynamics codes is presented. In laser produced plasmas, it is now believed that the heat transport can be strongly modified by the nonlocal nature of the electron conduction. Other mechanisms, such as self-generated magnetic fields, may also affect the heat transport. The model described in this work, based on simplified Fokker-Planck equations aims at extending the model of G. Schurtz, Ph. Nicolaï, and M. Busquet [Phys. Plasmas 7, 4238 (2000)] to magnetized plasmas. A complete system of nonlocal equations is derived from kinetic equations with self-consistent electric and magnetic fields. These equations are analyzed and simplified in order to be implemented into large laser fusion codes and coupled to other relevant physics. The model is applied to two laser configurations that demonstrate the main features of the model and point out the nonlocal Righi-Leduc effect in a multidimensional case.

  8. On the importance of specific heats as regards efficiency increases for highly dilute IC engines

    International Nuclear Information System (INIS)

    Caton, Jerald A.

    2014-01-01

    Highlights: • Importance of specific heats towards increasing engine efficiency was quantified. • Decreases of specific heats contribute 3.5–6.3% (abs) to the efficiency. • Dilute engines benefit from decreases of specific heats due to lower temperatures. - Abstract: Engineering and scientific efforts continue with the development of advanced, IC engines using highly dilute mixtures, and relatively high compression ratios. Such engines are known to provide opportunities for low emissions as well as high efficiencies. The main features of these engines include higher compression ratios, lean operation, use of EGR, and shorter burn durations. First, this study reviews the quantitative contributions of each of these features as determined by an engine cycle simulation. Second, this study provides the quantitative contributions to the increased efficiency in terms of fundamental thermodynamic considerations. An automotive engine operated at 2000 rpm was selected for this study. For the conditions examined, the net indicated thermal efficiency increased from 37.0% (conventional engine) to 53.9% (high efficiency engine) – for an incremental increase of 16.9% (absolute). The contribution of increases of the ratio of specific heats towards the final thermal efficiency is quantified. This aspect has been well known, but has not been quantified for actual engines. For the various conditions examined, 21–35% of the total efficiency improvement was estimated to be due to the increase of the ratio of specific heats

  9. Domain Specific Language for Magnetic Measurements at CERN

    CERN Document Server

    Petrone, C

    2009-01-01

    CERN, the European Organization for Nuclear Research, is one of the world’s largest and most respected centres for scientific research. Founded in 1954, the CERN Laboratory sits astride the Franco–Swiss border near Geneva. It was one of Europe’s first joint ventures and now has 20 Member States. Its main purpose is fundamental research in partcle physics, namely investigating what the Universe is made of and how it works. At CERN, the design and realization of the new particle accelerator, the Large Hadron Collider (LHC), has required a remarkable technological effort in many areas of engineering. In particular, the tests of LHC superconducting magnets disclosed new horizons to magnetic measurements. At CERN, the objectively large R&D effort of the Technolgy Department/Magnets, Superconductors and Cryostats (TE/MSC) group identified areas where further work is required in order to assist the LHC commissioning and start-up, to provide continuity in the instrumentation for the LHC magnets maintenance,...

  10. Ordering effects on structure and specific heat of nonstoichiometric titanium carbide

    International Nuclear Information System (INIS)

    Lipatnikov, V.N.; Gusev, A.I.

    1999-01-01

    The experimental results on the change in the crystal structure and specific heat of the nonstoichiometric titanium carbide TiC y (0.5 2 C phases with cubic and trigonal symmetry and the rhombic ordered Ti 3 C 2 phase are formed in the titanium carbide at the temperature below 1000 K by the phase transitions mechanism. The temperatures and heats of the order-disorder phase transitions are determined [ru

  11. Specific microRNAs Regulate Heat Stress Responses in Caenorhabditis elegans

    DEFF Research Database (Denmark)

    Nehammer, Camilla; Podolska, Agnieszka; Mackowiak, Sebastian D

    2015-01-01

    have identified additional functions for already known players (mir-71 and mir-239) as well as identifying mir-80 and the mir-229 mir-64-66 cluster as important regulators of the heat stress response in C. elegans. These findings uncover an additional layer of complexity to the regulation of stress...... to heat stress in Caenorhabditis elegans and show that a discrete subset of miRNAs is thermoregulated. Using in-depth phenotypic analyses of miRNA deletion mutant strains we reveal multiple developmental and post-developmental survival and behavioral functions for specific miRNAs during heat stress. We...

  12. Optimal size for heating efficiency of superparamagnetic dextran-coated magnetite nanoparticles for application in magnetic fluid hyperthermia

    Science.gov (United States)

    Shaterabadi, Zhila; Nabiyouni, Gholamreza; Soleymani, Meysam

    2018-06-01

    Dextran-coated magnetite (Fe3O4) nanoparticles with average particle sizes of 4 and 19 nm were synthesized through in situ and semi-two-step co-precipitation methods, respectively. The experimental results confirm the formation of pure phase of magnetite as well as the presence of dextran layer on the surface of modified magnetite nanoparticles. The results also reveal that both samples have the superparamagnetic behavior. Furthermore, calorimetric measurements show that the dextran-coated Fe3O4 nanoparticles with an average size of 4 nm cannot produce any appreciable heat under a biologically safe alternating magnetic field used in hyperthermia therapy; whereas, the larger ones (average size of 19 nm) are able to increase the temperature of their surrounding medium up to above therapeutic range. In addition, measured specific absorption rate (SAR) values confirm that magnetite nanoparticles with an average size of 19 nm are very excellent candidates for application in magnetic hyperthermia therapy.

  13. Specific heat of filled skutterudite PrOs4P12

    International Nuclear Information System (INIS)

    Matsuhira, Kazuyuki; Doi, Yoshihiro; Wakeshima, Makoto; Hinatsu, Yukio; Kihou, Kunihiro; Sekine, Chihiro; Shirotani, Ichimin

    2005-01-01

    We report the specific heat of filled skutterudite compounds PrOs 4 P 12 and LaOs 4 P 12 down to 1.8K. The specific heat divided by temperature C(T)/T in PrOs 4 P 12 shows a shoulder around 13K. This shoulder is caused by a Schottky anomaly due to a crystalline electric field effect. The electronic specific heat coefficients γ of PrOs 4 P 12 and LaOs 4 P 12 are estimated to be 56.5 and 21.6mJ/K 2 mol, respectively. The value of γ in PrOs 4 P 12 is 2.6 times larger than that in LaOs 4 P 12

  14. Beam Energy Scan of Specific Heat Through Temperature Fluctuations in Heavy Ion Collisions

    Science.gov (United States)

    Basu, Sumit; Nandi, Basanta K.; Chatterjee, Sandeep; Chatterjee, Rupa; Nayak, Tapan

    2016-01-01

    Temperature fluctuations may have two distinct origins, first, quantum fluctuations that are initial state fluctuations, and second, thermodynamical fluctuations. We discuss a method of extracting the thermodynamic temperature from the mean transverse momentum of pions, by using controllable parameters such as centrality of the system, and range of the transverse momenta. Event-by-event fluctuations in global temperature over a large phase space provide the specific heat of the system. We present Beam Energy Scan of specific heat from data, AMPT and HRG model prediction. Experimental results from NA49, STAR, PHENIX, PHOBOS and ALICE are combined to obtain the specific heat as a function of beam energy. These results are compared to calculations from AMPT event generator, HRG model and lattice calculations, respectively.

  15. Phonon spectrum of YBCO obtained by specific heat inversion method for real data

    CERN Document Server

    Tao Wen; Dai Xian Xi; Dai Ji Xin; Evenson, W E

    2003-01-01

    In this paper, the phonon spectrum of YBCO is obtained from experimental specific heat data by an exact inversion formula with a parameter for eliminating divergences. The results can be compared to those of neutron inelastic scattering, which can only be carried out in a few laboratories. Some key points of specific heat-phonon spectrum inversion (SPI) theory and a method of asymptotic behaviour control are discussed. An improved unique existence theorem is presented, and a universal function set for numerical calculation of SPI is calculated with high accuracy, which makes the inversion method applicable and convenient in practice. This is the first time specific heat-phonon SPI has been realized for a concrete system.

  16. Specific heat study of quasi-one-dimensional antiferromagnetic model for an organic polymer chain

    International Nuclear Information System (INIS)

    Qu Shaohua; Zhu Lin

    2008-01-01

    The specific heat of an infinite one-dimensional polymer chain bearing periodically arranged side radicals connected to the even sites is studied by means of quantum transfer-matrix method based on a Ising-Heisenberg model. In the absence of the exchange interactions between side radicals and the main chain, the curves of specific heat show a round peak due to the antiferromagnetic excitations for the all antiferromagnetic interactions along the polymer chain. Considering the exchange interactions between the side radicals and the main chain, the curves of the specific heat show double-peak structure for ferromagnetic interactions between the radicals and main chain, indicating that a competition between ferromagnetic and antiferromagnetic interactions and the possibility of the occurrence of the stable ferrimagnetic state along the polymer chain

  17. Negative specific heat, phase transition and particles spilling from a potential well

    International Nuclear Information System (INIS)

    Rao, J.; Liu, Q.H.; Liu, T.G.; Li, L.X.

    2008-01-01

    For a finite number of noninteracting particles in a box with a potential well in the center, the microcanonical kinetic energy in dependence on the total energy as it is negative can be classified into three categories. The first exhibits a monotonical rise and the specific heat is positive. The second shows a diminishing sawtooth wave with a global rise. The last corresponds to the extreme case and takes the regular sawtooth wave form. The sawtooth wave portion associates periodically a kinetic energy fall in spite of an increase of the total energy; and we attribute to such a fall the negative specific heat. The phase transition can be defined when the relatively dense particle state in the well and relatively dilute particle state in the rest volume of the box coexist, and the appearance of the negative specific heat is sufficient but not necessary for the onset of the phase transition

  18. Theoretical analysis for the specific heat and thermal parameters of solid C60

    Science.gov (United States)

    Soto, J. R.; Calles, A.; Castro, J. J.

    1997-08-01

    We present the results of a theoretical analysis for the thermal parameters and phonon contribution to the specific heat in solid C60. The phonon contribution to the specific heat is calculated through the solution of the corresponding dynamical matrix, for different points in the Brillouin zone, and the construccion of the partial and generalized phonon density of states. The force constants are obtained from a first principle calculation, using a SCF Hartree-Fock wave function from the Gaussian 92 program. The thermal parameters reported are the effective temperatures and vibrational amplitudes as a function of temperature. Using this model we present a parametization scheme in order to reproduce the general behaviour of the experimental specific heat for these materials.

  19. On the low-temperature specific heat of icosahedral and decagonal quasicrystals

    International Nuclear Information System (INIS)

    Chernikov, M.A.

    2005-01-01

    Calorimetric experiments on icosahedral (Al-Re-Pd, Al-Mn-Pd) and decagonal (Al-Cu-Co, Al-Ni-Co) quasicrystals are described. For quasicrystals of both classes, the coefficient γ of the linear term to the specific heat falls into the range of 0.1-0.6 mJ/g-atom K 2 indicating a low density of energy states at Fermi level. For icosahedral Al-Mn-Pd, the cubic-in-temperature term to the specific heat is distinctly larger than the estimated contribution of long-wave acoustic excitations. On the contrary, the magnitude of the cubic-in-temperature term to the specific heat of decagonal Al-Ni-Co is in agreement,within the experimental accuracy, with the Debye acoustic contribution from the results of low-temperature measurements of the elastic modules [ru

  20. Parallel transport of long mean-free-path plasma along open magnetic field lines: Parallel heat flux

    International Nuclear Information System (INIS)

    Guo Zehua; Tang Xianzhu

    2012-01-01

    In a long mean-free-path plasma where temperature anisotropy can be sustained, the parallel heat flux has two components with one associated with the parallel thermal energy and the other the perpendicular thermal energy. Due to the large deviation of the distribution function from local Maxwellian in an open field line plasma with low collisionality, the conventional perturbative calculation of the parallel heat flux closure in its local or non-local form is no longer applicable. Here, a non-perturbative calculation is presented for a collisionless plasma in a two-dimensional flux expander bounded by absorbing walls. Specifically, closures of previously unfamiliar form are obtained for ions and electrons, which relate two distinct components of the species parallel heat flux to the lower order fluid moments such as density, parallel flow, parallel and perpendicular temperatures, and the field quantities such as the magnetic field strength and the electrostatic potential. The plasma source and boundary condition at the absorbing wall enter explicitly in the closure calculation. Although the closure calculation does not take into account wave-particle interactions, the results based on passing orbits from steady-state collisionless drift-kinetic equation show remarkable agreement with fully kinetic-Maxwell simulations. As an example of the physical implications of the theory, the parallel heat flux closures are found to predict a surprising observation in the kinetic-Maxwell simulation of the 2D magnetic flux expander problem, where the parallel heat flux of the parallel thermal energy flows from low to high parallel temperature region.

  1. Specific heat of amorphous 3He films and confined liquid 3He

    International Nuclear Information System (INIS)

    Golov, A.; Pobell, F.

    1995-01-01

    We have measured the heat capacities of 3 He films and liquid 3 He in porous Vycor glass at 10 to 600 mK. With increasing the film thickness front 1 to 3 atomic layers , the specific heat evolves gradually from that typical to solid to that of liquid 3 He. At about 2 atomic layers, however, its low-temperature part is nearly temperature-independent; we interpret this as a result of gradual freezing of spins in an amorphous solid 3 He film with decreasing the temperature. The contribution of liquid 3 He in the center of the Vycor pores can be described as the specific heat of bulk liquid 3 He at corresponding pressures in the range 0 to 28 bar. The thickness of amorphous solid on the pore walls increases with external pressure roughly linearly. Preplating the walls with 4 He allows to determine the positions of 3 He atoms contributing to the surface specific heat at 10 to 50 mK. In addition, the contribution from the specific heat of 3 He- 4 He mixing at 100 to 600 mK is discussed as a function of pressure and amount of 4 He

  2. High performance wash-free magnetic bioassays through microfluidically enhanced particle specificity.

    Science.gov (United States)

    Bechstein, Daniel J B; Lee, Jung-Rok; Ooi, Chin Chun; Gani, Adi W; Kim, Kyunglok; Wilson, Robert J; Wang, Shan X

    2015-06-30

    Magnetic biosensors have emerged as a sensitive and versatile platform for high performance medical diagnostics. These magnetic biosensors require well-tailored magnetic particles as detection probes, which need to give rise to a large and specific biological signal while showing very low nonspecific binding. This is especially important in wash-free bioassay protocols, which do not require removal of particles before measurement, often a necessity in point of care diagnostics. Here we show that magnetic interactions between magnetic particles and magnetized sensors dramatically impact particle transport and magnetic adhesion to the sensor surfaces. We investigate the dynamics of magnetic particles' biomolecular binding and magnetic adhesion to the sensor surface using microfluidic experiments. We elucidate how flow forces can inhibit magnetic adhesion, greatly diminishing or even eliminating nonspecific signals in wash-free magnetic bioassays, and enhancing signal to noise ratios by several orders of magnitude. Our method is useful for selecting and optimizing magnetic particles for a wide range of magnetic sensor platforms.

  3. Specific heat of 4He and 3He--4He mixtures at their lambda transition

    International Nuclear Information System (INIS)

    Gasparini, F.M.; Moldover, M.R.

    1975-01-01

    We have measured the specific heat near the lambda transition of pure 4 He and of five 3 He-- 4 He mixtures up to a mole fraction of 0.39 3 He in 4 He. Our data for 4 He confirm the results of Ahlers revealing an asymmetry in the exponents above and below T/sub lambda/ when the specific heat is represented by a simple-power-law temperature dependence. Our results for these exponents (α = 0.012 plus-or-minus 0.002 and α' = -0.012 plus-or-minus 0.004) differ somewhat from Ahlers's. Our results can be reconciled with the requirement of scaling (α = α') only by supposing substantial contributions to C/sub p/ are made by singular correction terms to a simple power law. The measured specific heat of the mixtures richest in 3 He appears to be finite, continuous, and cusped at the lambda line. These qualitative features have been termed ''renormalization'' by Fisher. An analysis of our mixture data with a power-law temperature dependence does not yield a fully renormalized exponent, but rather an effective exponent. Derivatives at the lambda line were used to calculate the specific heat along paths of constant pressure and constant relative chemical potential.This specific heat behaves very much like C/sub p/ of pure 4 He, this behavior supporting the idea of universality for the specific-heat exponents. It is also true that the same asymmetry in the branches above and below T/sub lambda/ which is []bserved in pure 4 He is retained in the mixtures. The persistence of the asymmetry of C/subp//sub phi/ as one moves along the lambda line towards increasing 3 He concentration (at the saturated vapor pressure of the mixtures) is analogous to the persistence of the asymmetry of C/subp/ as one moves along the lambda line towards increasing pressure in pure 4 He

  4. Material impacts and heat flux characterization of an electrothermal plasma source with an applied magnetic field

    Science.gov (United States)

    Gebhart, T. E.; Martinez-Rodriguez, R. A.; Baylor, L. R.; Rapp, J.; Winfrey, A. L.

    2017-08-01

    To produce a realistic tokamak-like plasma environment in linear plasma device, a transient source is needed to deliver heat and particle fluxes similar to those seen in an edge localized mode (ELM). ELMs in future large tokamaks will deliver heat fluxes of ˜1 GW/m2 to the divertor plasma facing components at a few Hz. An electrothermal plasma source can deliver heat fluxes of this magnitude. These sources operate in an ablative arc regime which is driven by a DC capacitive discharge. An electrothermal source was configured with two pulse lengths and tested under a solenoidal magnetic field to determine the resulting impact on liner ablation, plasma parameters, and delivered heat flux. The arc travels through and ablates a boron nitride liner and strikes a tungsten plate. The tungsten target plate is analyzed for surface damage using a scanning electron microscope.

  5. Specific heat jump at T/sub c/ of proximity effect sandwiches containing nonmagnetic localized states

    International Nuclear Information System (INIS)

    Maneeratankul, S.; Tang, I.M.

    1987-01-01

    The decrease in the transition temperature and the jump in the specific heat at T/sub c/ of proximity effect sandwiches containing nonmagnetic Anderson impurities in the normal layer are studied. The effects of the resonant scattering by the impurities are treated in the same manner as that used by Kaiser in his study of the effects of resonant scattering on the properties of bulk superconductors. Numerical calculations of the decrease in T/sub c/ and the jump in the specific heat at T/sub c/ as a function of the thickness of the normal layer are presented

  6. Specific heat studies of pure Nb3Sn single crystals at low temperature

    International Nuclear Information System (INIS)

    Escudero, R; Morales, F; Bernes, S

    2009-01-01

    Specific heat measurements performed on high purity vapor-grown Nb 3 Sn crystals show clear features related to both the martensitic and superconducting transitions. Our measurements indicate that the martensitic anomaly does not display hysteresis, meaning that the martensitic transition could be a weak first-order or a second-order thermodynamic transition. Careful measurements of the two transition temperatures display an inverse correlation between them. At low temperature, specific heat measurements show the existence of a single superconducting energy gap feature.

  7. Elastic modulus, thermal expansion, and specific heat at a phase transition

    International Nuclear Information System (INIS)

    Testardi, L.R.

    1975-01-01

    The interrelation of the elastic modulus, thermal-expansion coefficient, and specific heat of a transformed phase relative to the untransformed phase is calculated assuming a particular but useful form of the thermodynamic potential. For second-order phase transitions where this potential applies, measurements of modulus, expansion, and specific heat can yield the general (longitudinal as well as shear) first- and second-order stress (or strain) dependences of the transition temperature and of the order parameter at absolute zero. An exemplary application to one type of phase transition is given

  8. Specific heats of lunar surface materials from 90 to 350 degrees Kelvin

    Science.gov (United States)

    Robie, R.A.; Hemingway, B.S.; Wilson, W.H.

    1970-01-01

    The specific heats of lunar samples 10057 and 10084 returned by the Apollo 11 mission have been measured between 90 and 350 degrees Kelvin by use of an adiabatic calorimeter. The samples are representative of type A vesicular basalt-like rocks and of finely divided lunar soil. The specific heat of these materials changes smoothly from about 0.06 calorie per gram per degree at 90 degrees Kelvin to about 0.2 calorie per gram per degree at 350 degrees Kelvin. The thermal parameter ??=(k??C)-1/2 for the lunar surface will accordingly vary by a factor of about 2 between lunar noon and midnight.

  9. Structure of slow shocks in a magnetized plasma with heat conduction

    International Nuclear Information System (INIS)

    Tsai, C.L.; Tsai, R.H.; Wu, B.H.; Lee, L.C.

    2002-01-01

    The structure of slow shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. In this study, a pair of slow shocks is formed through the evolution of a current sheet initiated by the presence of a normal magnetic field. It is found that the slow shock consists of two parts: The isothermal main shock and foreshock. Significant jumps in plasma density, velocity and magnetic field occur across the main shock, but the temperature is found to be continuous across the main shock. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. It is shown that the jumps in plasma density, pressure, velocity, and magnetic field across the main shock are determined by the set of modified isothermal Rankine-Hugoniot conditions. It is also found that a jump in the temperature gradient is present across the main shock in order to satisfy the energy conservation. The present results can be applied to the heating in the solar corona and solar wind

  10. On Electromagnetic Modulation of Flow Instabilities, Mixing and Heat Transfer in Conducting and Magnetized Fluids

    Science.gov (United States)

    Kenjeres, S.

    2016-09-01

    In the present paper we give a concise review of some recent highlights of our research dealing with electromagnetic control of flow, mixing and heat transfer of electrically conductive or magnetized fluids. We apply a combination of state-of-art numerical (DNS and LES) and experimental (PIV and LIF) techniques to provide fundamental insights into the complex phenomena of interactions between imposed (or induced) electromagnetic fields and underlying fluid flow. Our analysis covers an extensive range of working fluids, i.e. weakly- and highly-electrically-conductive, as well as magnetized fluids. These interactions are defined through the presence of different types of body forces acting per volume of fluid. A fully closed system of governing equations containing an extended set of the Navier-Stokes and a simplified set of the Maxwell equations is presented. The four characteristic examples are selected: the electromagnetic control of self-sustained jet oscillations, the electromagnetic enhancement of heat transfer in thermal convection, the wake interactions behind magnetic obstacles and finally, the thermo-magnetic convection in differentially heated cubical enclosure. The comparative assessment between experimental and numerical results is presented. It is concluded that generally good agreement between simulations and experiments is obtained for all cases considered, proving the concept of electromagnetic modulation, which can be used in numerous technological applications.

  11. Magnetic Characteristics of Active Region Heating Observed with TRACE, SOHO/EIT, and Yohkoh/SXT

    Science.gov (United States)

    Porter, J. G.; Falconer, D. A.; Moore, R. L.; Rose, M. Franklin (Technical Monitor)

    2001-01-01

    Over the past several years, we have reported results from studies that have compared the magnetic structure and heating of the transition region and corona (both in active regions and in the quiet Sun) by combining X-ray and EUV images from Yohkoh and Solar and Heliospheric Observatory (SOHO) with photospheric magnetograms from ground-based observatories. Our findings have led us to the hypothesis that most heating throughout the corona is driven from near and below the base of the corona by eruptive microflares occurring in compact low-lying "core magnetic fields (i.e., fields rooted along and closely enveloping polarity inversion lines in the photospheric magnetic flux). We now extend these studies, comparing sequences of UV images from Transition Region and Coronal Explorer (TRACE) with longitudinal magnetograms from Kitt Peak and vector magnetograms from MUSIC. These comparisons confirm the previous results regarding the importance of core-field activity to active region heating. Activity in fields associated with satellite polarity inclusions and/or magnetically sheared configurations is especially prominent. This work is funded by NASA's Office of Space Science through the Sun-Earth Connection Guest Investigator Program and the Solar Physics Supporting Research and Technology Program.

  12. Magnetic hyperthermia properties of nanoparticles inside lysosomes using kinetic Monte Carlo simulations: Influence of key parameters and dipolar interactions, and evidence for strong spatial variation of heating power

    Science.gov (United States)

    Tan, R. P.; Carrey, J.; Respaud, M.

    2014-12-01

    Understanding the influence of dipolar interactions in magnetic hyperthermia experiments is of crucial importance for fine optimization of nanoparticle (NP) heating power. In this study we use a kinetic Monte Carlo algorithm to calculate hysteresis loops that correctly account for both time and temperature. This algorithm is shown to correctly reproduce the high-frequency hysteresis loop of both superparamagnetic and ferromagnetic NPs without any ad hoc or artificial parameters. The algorithm is easily parallelizable with a good speed-up behavior, which considerably decreases the calculation time on several processors and enables the study of assemblies of several thousands of NPs. The specific absorption rate (SAR) of magnetic NPs dispersed inside spherical lysosomes is studied as a function of several key parameters: volume concentration, applied magnetic field, lysosome size, NP diameter, and anisotropy. The influence of these parameters is illustrated and comprehensively explained. In summary, magnetic interactions increase the coercive field, saturation field, and hysteresis area of major loops. However, for small amplitude magnetic fields such as those used in magnetic hyperthermia, the heating power as a function of concentration can increase, decrease, or display a bell shape, depending on the relationship between the applied magnetic field and the coercive/saturation fields of the NPs. The hysteresis area is found to be well correlated with the parallel or antiparallel nature of the dipolar field acting on each particle. The heating power of a given NP is strongly influenced by a local concentration involving approximately 20 neighbors. Because this local concentration strongly decreases upon approaching the surface, the heating power increases or decreases in the vicinity of the lysosome membrane. The amplitude of variation reaches more than one order of magnitude in certain conditions. This transition occurs on a thickness corresponding to approximately

  13. Kalman Filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry.

    Science.gov (United States)

    Zhang, Yuxin; Chen, Shuo; Deng, Kexin; Chen, Bingyao; Wei, Xing; Yang, Jiafei; Wang, Shi; Ying, Kui

    2017-01-01

    To develop a self-adaptive and fast thermometry method by combining the original hybrid magnetic resonance thermometry method and the bio heat transfer equation (BHTE) model. The proposed Kalman filtered Bio Heat Transfer Model Based Self-adaptive Hybrid Magnetic Resonance Thermometry, abbreviated as KalBHT hybrid method, introduced the BHTE model to synthesize a window on the regularization term of the hybrid algorithm, which leads to a self-adaptive regularization both spatially and temporally with change of temperature. Further, to decrease the sensitivity to accuracy of the BHTE model, Kalman filter is utilized to update the window at each iteration time. To investigate the effect of the proposed model, computer heating simulation, phantom microwave heating experiment and dynamic in-vivo model validation of liver and thoracic tumor were conducted in this study. The heating simulation indicates that the KalBHT hybrid algorithm achieves more accurate results without adjusting λ to a proper value in comparison to the hybrid algorithm. The results of the phantom heating experiment illustrate that the proposed model is able to follow temperature changes in the presence of motion and the temperature estimated also shows less noise in the background and surrounding the hot spot. The dynamic in-vivo model validation with heating simulation demonstrates that the proposed model has a higher convergence rate, more robustness to susceptibility problem surrounding the hot spot and more accuracy of temperature estimation. In the healthy liver experiment with heating simulation, the RMSE of the hot spot of the proposed model is reduced to about 50% compared to the RMSE of the original hybrid model and the convergence time becomes only about one fifth of the hybrid model. The proposed model is able to improve the accuracy of the original hybrid algorithm and accelerate the convergence rate of MR temperature estimation.

  14. Investigating the efficacy of magnetic nanofluid as a coolant in double-pipe heat exchanger in the presence of magnetic field

    International Nuclear Information System (INIS)

    Bahiraei, Mehdi; Hangi, Morteza

    2013-01-01

    Highlights: • Efficacy of magnetic nanofluid as coolant was studied in double-pipe heat exchanger. • Effect of applying quadrupole magnetic field with different magnitudes was analyzed. • Magnetic force makes the concentration distribution more uniform in tube side. • Applying magnetic field enhances both pressure drop and heat transfer. • Optimization was performed to reach maximum heat transfer and minimum pressure drop. - Abstract: The current study attempts to investigate the performance of water based Mn–Zn ferrite magnetic nanofluid in a counter-flow double-pipe heat exchanger under quadrupole magnetic field using the two-phase Euler–Lagrange method. The nanofluid flows in the tube side as coolant, while the hot water flows in the annulus side. The effects of different parameters including concentration, size of the particles, magnitude of the magnetic field and Reynolds number are examined. Distribution of the particles is non-uniform at the cross section of the tube such that the concentration is higher at central regions of the tube. Application of the magnetic field makes the distribution of particles more uniform and this uniformity increases by increasing the distance from the tube inlet. Increasing each of the parameters of concentration, particle size and magnitude of the magnetic field will lead to a greater pressure drop and also higher heat transfer improvement. At higher Reynolds numbers, the effect of magnetic force is diminished. Optimization was performed using genetic algorithm coupled with compromise programming technique in order to reach the maximum overall heat transfer coefficient along with the minimum pressure drop. For this purpose, the models of objective functions of overall heat transfer coefficient and pressure drop of the nanofluid were first extracted in terms of the effective parameters using neural network. The neural network model predicts the output variables with a very good accuracy. The optimal values were

  15. Quantifying variety-specific heat resistance and the potential for adaptation to climate change.

    Science.gov (United States)

    Tack, Jesse; Barkley, Andrew; Rife, Trevor W; Poland, Jesse A; Nalley, Lawton Lanier

    2016-08-01

    The impact of climate change on crop yields has become widely measured; however, the linkages for winter wheat are less studied due to dramatic weather changes during the long growing season that are difficult to model. Recent research suggests significant reductions under warming. A potential adaptation strategy involves the development of heat resistant varieties by breeders, combined with alternative variety selection by producers. However, the impact of heat on specific wheat varieties remains relatively unstudied due to limited data and the complex genetic basis of heat tolerance. Here, we provide a novel econometric approach that combines field-trial data with a genetic cluster mapping to group wheat varieties and estimate a separate extreme heat impact (temperatures over 34 °C) across 24 clusters spanning 197 varieties. We find a wide range of heterogeneous heat resistance and a trade-off between average yield and resistance. Results suggest that recently released varieties are less heat resistant than older varieties, a pattern that also holds for on-farm varieties. Currently released - but not yet adopted - varieties do not offer improved resistance relative to varieties currently grown on farm. Our findings suggest that warming impacts could be significantly reduced through advances in wheat breeding and/or adoption decisions by producers. However, current adaptation-through-adoption potential is limited under a 1 °C warming scenario as increased heat resistance cannot be achieved without a reduction in average yields. © 2015 John Wiley & Sons Ltd.

  16. Determination of the specific heat petroleum derivates; Determinacao do calor especifico de derivados ultrapesados de petroleo

    Energy Technology Data Exchange (ETDEWEB)

    Ballesteros Hernandez, Julie A.; Zuniga Linan, Lamia; Jardini, Andre; Maciel, Maria Regina Wolf; Maciel Filho, Rubens Maciel [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Quimica; Medina, Lilian Carmen [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil). Centro de Pesquisas (CENPES)

    2008-07-01

    In the development of the specific mathematical modeling for heavy and ultra heavy petroleum fractions in a molecular distiller is very important the definition of physical and chemical parameters as density and specific heat of the mixture, the enthalpy of vaporization, among others, since they are used in the energy balance. Information on these properties and their variation with temperature are found in the open literature for mixture with few components (simple mixtures). However, for multicomponent solutions consisting of complex mixtures such as oil and its heavy and ultraheavy fractions, available data are few, or are limited to low temperatures. The specific heat is an important property in the energy balance. This property can be measured by Differential Scanning Calorimetry (DSC), which gives results with great sensitivity and accuracy. This paper presents the variation of specific heat with the temperature of ultra-heavy oil fractions in the range from 80 deg to 350 deg C . Through the study of this variation, the equation nowadays used can be adjusted, in order to determine the specific heat. New values of the constants are determined, so that the equation can be used for these complex products, optimizing the estimative of Cp and so no experimental data are always necessary for simulations. (author)

  17. Anomalous heating and plasmoid formation in pulsed power driven magnetic reconnection experiments

    Science.gov (United States)

    Hare, Jack

    2017-10-01

    Magnetic reconnection is an important process occurring in various plasma environments, including high energy density plasmas. In this talk we will present results from a recently developed magnetic reconnection platform driven by the MAGPIE pulsed power generator (1 MA, 250 ns) at Imperial College London. In these experiments, supersonic, sub-Alfvénic plasma flows collide, bringing anti-parallel magnetic fields into contact and producing a well-defined, elongated reconnection layer. This layer is long-lasting (>200 ns, > 10 hydrodynamic flow times) and is diagnosed using a suite of high resolution, spatially and temporally resolved diagnostics which include laser interferometry, Thomson scattering and Faraday rotation imaging. We observe significant heating of the electrons and ions inside the reconnection layer, and calculate that the heating must occur on time-scales far faster than can be explained by classical mechanisms. Possible anomalous mechanisms include in-plane electric fields caused by two-fluid effects, and enhanced resistivity and viscosity caused by kinetic turbulence. We also observe the repeated formation of plasmoids in the reconnection layer, which are ejected outwards along the layer at super-Alfvénic velocities. The O-point magnetic field structure of these plasmoids is determined using in situ magnetic probes, and these plasmoids could also play a role in the anomalous heating of the electrons and ions. In addition, we present further modifications to this experimental platform which enable us to study asymmetric reconnection or measure the out-of-plane magnetic field inside the plasmoids. This work was supported in part by the Engineering and Physical Sciences Research Council (EPSRC) Grant No. EP/N013379/1, and by the U.S. Department of Energy (DOE) Awards No. DE-F03-02NA00057 and No. DE-SC-0001063.

  18. Formation of toroidal pre-heat plasma without residual magnetic field for high-beta pinch experiments

    International Nuclear Information System (INIS)

    Ikeda, Nagayasu; Tamaru, Ken; Nagata, Akiyoshi.

    1979-01-01

    Formation of toroidal pre-heat plasma was studied. The pre-heat plasma without residual magnetic field was made by chopping the current for pre-heat, A small toroidal-pinch system was used for the experiment. The magnetic field was measured with a magnetic probe. One turn loop was used for the measurement of the toroidal one-turn electric field. A pair of Rogoski coil was used for the measurement of plasma current. The dependence of residual magnetic field on chopping time was measured. By fast chopping of the primary current in the pre-heating circuit, the poloidal magnetic field was reduced to several percent within 5 microsecond. After chopping, no instability was observed in the principal discharge plasma produced within several microsecond. As the conclusion, it can be said that the control of residual field can be made by current chopping. (Kato, T.)

  19. Falkner-Skan Flow of a Maxwell Fluid with Heat Transfer and Magnetic Field

    Directory of Open Access Journals (Sweden)

    M. Qasim

    2013-01-01

    Full Text Available This investigation deals with the Falkner-Skan flow of a Maxwell fluid in the presence of nonuniform applied magnetic fi…eld with heat transfer. Governing problems of flow and heat transfer are solved analytically by employing the homotopy analysis method (HAM. Effects of the involved parameters, namely, the Deborah number, Hartman number, and the Prandtl number, are examined carefully. A comparative study is made with the known numerical solution in a limiting sense and an excellent agreement is noted.

  20. Specific heat measurement set-up for quench condensed thin superconducting films.

    Science.gov (United States)

    Poran, Shachaf; Molina-Ruiz, Manel; Gérardin, Anne; Frydman, Aviad; Bourgeois, Olivier

    2014-05-01

    We present a set-up designed for the measurement of specific heat of very thin or ultra-thin quench condensed superconducting films. In an ultra-high vacuum chamber, materials of interest can be thermally evaporated directly on a silicon membrane regulated in temperature from 1.4 K to 10 K. On this membrane, a heater and a thermometer are lithographically fabricated, allowing the measurement of heat capacity of the quench condensed layers. This apparatus permits the simultaneous thermal and electrical characterization of successively deposited layers in situ without exposing the deposited materials to room temperature or atmospheric conditions, both being irreversibly harmful to the samples. This system can be used to study specific heat signatures of phase transitions through the superconductor to insulator transition of quench condensed films.

  1. Comparison of air-standard rectangular cycles with different specific heat models

    International Nuclear Information System (INIS)

    Wang, Chao; Chen, Lingen; Ge, Yanlin; Sun, Fengrui

    2016-01-01

    Highlights: • Air-standard rectangular cycle models are built and investigated. • Finite-time thermodynamics is applied. • Different dissipation models and variable specific heats models are adopted. • Performance characteristics of different cycle models are compared. - Abstract: In this paper, performance comparison of air-standard rectangular cycles with constant specific heat (SH), linear variable SH and non-linear variable SH are conducted by using finite time thermodynamics. The power output and efficiency of each cycle model and the characteristic curves of power output versus compression ratio, efficiency versus compression ratio, as well as power output versus efficiency are obtained by taking heat transfer loss (HTL) and friction loss (FL) into account. The influences of HTL, FL and SH on cycle performance are analyzed by detailed numerical examples.

  2. Specific features of the motion of neutrons in a medium with a helical magnetic structure

    International Nuclear Information System (INIS)

    Fraerman, A. A.; Udalov, O. G.

    2007-01-01

    The specific features of the motion of neutrons in a noncoplanar magnetic field are considered by an example of the magnetization distribution in the form of a conical helix. The reflection coefficients of neutrons from holmium crystals are calculated. It is shown that, for a noncoplanar distribution of a magnetic field in a crystal, the reflection coefficient of neutrons with spin flip exhibits an additional feature

  3. Lattice specific heat and local density of states of Ni-based dilute ...

    Indian Academy of Sciences (India)

    The required perfect lattice phonons of Ni are calculated using a general 4 Th neighbour force model derived by Birge- neau et al [14], on the basis of Born Von Karman fit to the measured dispersion curves in neutron scattering experiments. A comparison of calculated and experi- mental lattice specific heat provides us an ...

  4. Investigation of enthalpy and specific heat of the gallium-indium-tin eutectic alloy

    International Nuclear Information System (INIS)

    Roshchupkin, V.V.; Migaj, L.L.; Fordeeva, L.K.; Perlova, N.L.

    1978-01-01

    Enthalpy and specific heat of the fusible (melting point is 10.6 deg C) eutectic alloy (67% Ga - 20.5% In - 12.5% Sn according to mass) are determined by the mixing method. The determination was carried out in vacuum at the residual pressure of >= 1x10 -5 torr in the temperature range from 59.3 to 437.0 deg C. It is established that temperature dependence of alloy enthalpy is described by the equation: Hsub(t) - Hsub(0degC)=1.014+0.0879t-0.0000129 t 2 , where (Hsub(t) - Hsub(0degC)) is enthalpy, cal/g; t-temperature, deg C. Mean-square dispersion is +-0.6%. Temperature dependence of alloy specific heat in the temperature range under study was determined by differentiation of the equation obtained for enthalpy: Csub(p)=0.0879-0.000026t, where Csub(p)-specific heat, cal/gx deg. It is supposed that temperature increase makes it possible to decrease slightly specific heat

  5. Low-temperature specific-heat and thermal-conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.

    1992-01-01

    Specific heat, C(p), and thermal conductivity, lambda, have been measured on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Results for both C(p)(T) and lambda(T) confirm that the different length-scale regions observed in the aerogel structure are reflected...

  6. Low-temperature specific heat and thermal conductivity of silica aerogels

    DEFF Research Database (Denmark)

    Sleator, T.; Bernasconi, A.; Posselt, D.

    1991-01-01

    Specific-heat and thermal-conductivity measurements were made on a series of base-catalyzed silica aerogels at temperatures between 0.05 and 20 K. Evidence for a crossover between regimes of characteristically different excitations was observed. The data analysis indicates a "bump" in the density...

  7. Summary of some feasibility studies for site-specific solar industrial process heat

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-01-01

    Some feasibility studies for several different site specific solar industrial process heat applications are summarized. The followng applications are examined. Leather Tanning; Concrete Production: Lumber and Paper Processing; Milk Processing; Molding, Curing or Drying; Automobile Manufacture; and Food Processing and Preparation. For each application, site and process data, system design, and performance and cost estimates are summarized.

  8. Laboratory Activity: Specific Heat by Change in Internal Energy of Silly Putty

    Science.gov (United States)

    Koser, John

    2011-01-01

    Students in introductory physics courses often don't study thermodynamics or thermodynamic events. If any thermal physics is taught in introductory courses (e.g., Physics 101 for Liberal Arts Majors), it usually involves the concepts of specific heat and various temperature scales. Seldom are the first and second laws of thermodynamics taught in…

  9. Effect of heat treatment on interface driven magnetic properties of CoFe films

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Akhilesh Kr., E-mail: drakhintu@gmail.com; Hsu, Jen-Hwa

    2017-06-15

    Highlights: • Ta underlayer and cap layer dependent anisotropy nature in thin CoFe films. • Thin Ta layer induces the magnetization component along normal to the film plane. • Heat treatment and Ta layers driven surface morphology, roughness and grain size. • Roughness reduces more than an order of magnitude with 2 nm Ta cap layer. • H{sub C}, domain patterns and domain size depend on Ta layers and heat treatment. - Abstract: We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (T{sub A} = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M–H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for T{sub A} above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (H{sub C}) shows a strong variation with T{sub A}, underlayer and cap layers. H{sub C} increases significantly with Ta underlayer and cap layers. The out of plane M–H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on T{sub A} and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the T{sub A}, and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the T{sub A}. Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also

  10. Effect of heat treatment on interface driven magnetic properties of CoFe films

    International Nuclear Information System (INIS)

    Singh, Akhilesh Kr.; Hsu, Jen-Hwa

    2017-01-01

    Highlights: • Ta underlayer and cap layer dependent anisotropy nature in thin CoFe films. • Thin Ta layer induces the magnetization component along normal to the film plane. • Heat treatment and Ta layers driven surface morphology, roughness and grain size. • Roughness reduces more than an order of magnitude with 2 nm Ta cap layer. • H C , domain patterns and domain size depend on Ta layers and heat treatment. - Abstract: We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (T A = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M–H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for T A above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (H C ) shows a strong variation with T A , underlayer and cap layers. H C increases significantly with Ta underlayer and cap layers. The out of plane M–H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on T A and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the T A , and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the T A . Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also show a smooth surface at a wide

  11. Stage- and sex-specific heat tolerance in the yellow dung fly Scathophaga stercoraria

    OpenAIRE

    Blanckenhorn Wolf U.; Gautier Roland; Nick Marcel; Puniamoorthy Nalini; Schäfer Martin A.

    2014-01-01

    Thermal tolerance varies at all hierarchical levels of biological organization: among species populations individuals and even within individuals. Age or developmental stage and sex specific thermal effects have received relatively little attention in the literature despite being crucial for understanding thermal adaptation in nature and responses to global warming. We document stage and sex specific heat tolerance in the yellow dung fly Scathophaga stercoraria (Diptera: Scathophagidae) a...

  12. Cytokines profile changers after magnetic-heat-vibromassage in chronic abacterial prostatitis with erectile disfunction

    Directory of Open Access Journals (Sweden)

    D. G. Коren’kov

    2016-01-01

    Full Text Available The aim of the study was to examine the influence of magnetic-heat-vibromassage procedure in treatment of 27 patients with chronic abacterial prostatitis with erectile dysfunction, by mean of transrectal electrodes application of MAVIT® apparatus (ULP-01-“ELAT”. In the prostatic gland (PG media and blood plasma the pro-inflammatory cytokine concentrations was investigated. PG hemodynamic, and erectile dysfunction also was determined. Control group was presented by 10 healthy males (23–45 years old. Measurements were done before treatment, and after 10 procedures of PG massage, and 30 days after procedure.It was shown that chronic abacterial prostatitis with erectile dysfunction with low clinical performance is supported by pro-inflammatory cytokines produced by the PG. The usage of magnetic-heat-vibromassage procedure increased prostatic microcirculation, as well as testosterone level, and improved the erectile dysfunction in all 27 patients enrolled into the study

  13. Wave heating and the U.S. magnetic fusion energy program

    International Nuclear Information System (INIS)

    Staten, H.S.

    1985-01-01

    The U.S. Government's support of the fusion program is predicated upon the long-term need for the fusion option in our energy future, as well as the near-term benefits associated with developments on the frontier of science and high technology. As a long-term energy option, magnetic fusion energy has the potential to provide an inexpensive, vast, and secure fuel reserve, to be environmentally clean and safe. It has many potential uses, which include production of central station electricity, fuel for fission reactors, synthetic fuels, and process heat for such applications as desalination of sea water. This paper presents an overview of the U.S. Government program for magnetic fusion energy. The goal and objectives of the U.S. program are reviewed followed by a summary of plasma experiments presently under way and the application of wave heating to these experiments

  14. Prototyping Energy Efficient Thermo-Magnetic & Induction Hardening for Heat Treat & Net Shape Forming Applications

    Energy Technology Data Exchange (ETDEWEB)

    Aquil Ahmad

    2012-08-03

    Within this project, Eaton undertook the task of bringing about significant impact with respect to sustainability. One of the major goals for the Department of Energy is to achieve energy savings with a corresponding reduction in carbon foot print. The use of a coupled induction heat treatment with high magnetic field heat treatment makes possible not only improved performance alloys, but with faster processing times and lower processing energy, as well. With this technology, substitution of lower cost alloys for more exotic alloys became a possibility; microstructure could be tailored for improved magnetic properties or wear resistance or mechanical performance, as needed. A prototype commercial unit has been developed to conduct processing of materials. Testing of this equipment has been conducted and results demonstrate the feasibility for industrial commercialization.

  15. Approximate method for calculating heat conditions in the magnetic circuits of transformers and betatrons

    International Nuclear Information System (INIS)

    Loginov, V.S.

    1986-01-01

    A technique for engineering design of two-dimensional stationary temperature field of rectangular cross section blending pile with inner heat release under nonsymmetrical cooling conditions is suggested. Area of its practical application is determined on the basis of experimental data known in literature. Different methods for calculating temperature distribution in betatron magnetic circuit are compared. Graph of maximum temperature calculation error on the basis of approximated expressions with respect to exact solution is given

  16. Improvement of stability of Nb3 Sn superconductors by introducing high specific heat substances

    Energy Technology Data Exchange (ETDEWEB)

    Xu, X. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Li, P. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Zlobin, A. V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Peng, X. [Unlisted, US, OH

    2018-01-24

    High-Jc Nb3Sn conductors have low stability against perturbations, which accounts for the slow training rates of high-field Nb3Sn magnets. While it is known that adding substances with high specific heat (C) into Nb3Sn wires can increase their overall specific heat and thus improve their stability, there has not been a practical method that is compatible with the fabrication of long-length conductors. In this work, we put forward a scheme to introduce such substances to distributed-barrier Nb3Sn wires, which adds minimum difficulty to the wire manufacturing process. Multifilamentary wires using a mixture of Cu and high-C Gd2O3 powders have been successfully fabricated along this line. Measurements showed that addition of Gd2O3 had no negative effects on residual resitivity ratio or non-Cu Jc, and that flux jumps were remarkably reduced, and minimum quench energy values at 4.2 K, 14 T were increased by a factor of three, indicating that stability was significantly improved. We also discussed the influences of the positioning of high-C substances and their thermal diffusivity on their effectiveness in reducing the superconductor temperature rise against perturbations. Based on these results, we proposed an optimized conductor architecture to maximize the effectiveness of this approach.

  17. Melting of the flux line lattice observed by specific heat experiments in YBa2Cu3O7-δ

    International Nuclear Information System (INIS)

    Roulin, M.; Junod, A.; Erb, A.; Walker, E.

    1996-01-01

    High resolution adiabatic specific heat experiments on YBa 2 Cu 3 O 7-δ (0≤δ≤0.05) are performed in magnetic fields from 0 to 14 T (B parallel c and B perpendicular c). In a 0.3 gram, twinned crystal with strong pinning, a step is consistently observed at the melting temperature T m of the vortex solid up to a critical point that depends on δ. The field B m and step temperature T m obey the relation B m =B m0 (δ)(1-T m /T c ) ∼4/3 . The anisotropy of B m and that of the upper critical field B c2 are found to be equal. Alternatively, in a 18 mg, twinned crystal of high purity with low pinning, first-order-like specific heat peaks are observed on the melting line from 8 to 14 T. The entropy under these peaks is ∼0.5 k B /vortex/bilayer. These characteristic features are attributed to the melting of a vortex glass in the former case and that of a vortex lattice in the latter case

  18. Divertor Heat Flux Reduction by Resonant Magnetic Perturbations in the LHD-Type Helical DEMO Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Yanagi, N.; Sagara, A.; Goto, T.; Masuzaki, S.; Miyazawa, J., E-mail: yanagi@lhd.nifs.ac.jp [National Institute for Fusion Science, Toki (Japan)

    2012-09-15

    Full text: The conceptual design studies of the LHD-type helical fusion DEMO reactor, FFHR-d1, are progressing steadfastly. The LHD-type heliotron magnetic configuration equipped with the built- in helical divertors has a potential to realize low divertor heat flux in spatial average. However, the toroidal asymmetry may give more than a couple of times higher peak heat flux at some locations, as has been experimentally observed in LHD and confirmed by magnetic field-line tracing. By providing radiation dispersion accompanied with a plasma detachment, the heat flux may decrease significantly though the compatibility with a good core plasma confinement is an important issue to be explored. Whereas the engineering difficulties for developing materials to be used under the neutron environment require even further decrease of the heat flux (even though the heliotron is a unique configuration that divertor plates be largely shielded from the direct irradiation of neutrons by breeder blankets). In this respect, we proposed, in the last IAEA FEC, a new strike point sweeping scheme using a set of auxiliary helical coils, termed helical divertor (HD) coils. The HD coils carrying a few percent of the current amplitude of the main helical coils sweep the divertor strike points without altering the core plasma. Though this scheme is effective in dispersing the heat flux in the poloidal direction, the toroidal asymmetry still remains. The AC operation may also give unforeseen engineering difficulties. We here propose that the peak heat flux be mitigated using RMP fields in steady-state. The magnetic field-lines are numerically traced in the vacuum configuration and their footprints coming to the divertor regions are counted. Their fraction plotted as a function of the toroidal angle indicates that the peak heat flux be mitigated to {approx} 20 MW per square meters at 3 GW fusion power generation without having radiation dispersion when an RMP field is applied. We note that the

  19. Numerical Study of Erosion, Heating, and Acceleration of the Magnetic Cloud as Impacted by Fast Shock

    International Nuclear Information System (INIS)

    Mao, Shoudi; He, Jiansen; Yang, Liping; Wang, Linghua; Zhang, Lei

    2017-01-01

    The impact of an overtaking fast shock on a magnetic cloud (MC) is a pivotal process in CME–CME (CME: coronal mass ejection) interactions and CME–SIR (SIR: stream interaction region) interactions. MC with a strong and rotating magnetic field is usually deemed a crucial part of CMEs. To study the impact of a fast shock on an MC, we perform a 2.5 dimensional numerical magnetohydrodynamic simulation. Two cases are run in this study: without and with impact by fast shock. In the former case, the MC expands gradually from its initial state and drives a relatively slow magnetic reconnection with the ambient magnetic field. Analyses of forces near the core of the MC as a whole body indicates that the solar gravity is quite small compared to the Lorentz force and the pressure gradient force. In the second run, a fast shock propagates, relative to the background plasma, at a speed twice that of the perpendicular fast magnetosonic speed, catches up with and takes over the MC. Due to the penetration of the fast shock, the MC is highly compressed and heated, with the temperature growth rate enhanced by a factor of about 10 and the velocity increased to about half of the shock speed. The magnetic reconnection with ambient magnetic field is also sped up by a factor of two to four in reconnection rate as a result of the enhanced density of the current sheet, which is squeezed by the forward motion of the shocked MC.

  20. Numerical Study of Erosion, Heating, and Acceleration of the Magnetic Cloud as Impacted by Fast Shock

    Energy Technology Data Exchange (ETDEWEB)

    Mao, Shoudi; He, Jiansen; Yang, Liping; Wang, Linghua [School of Earth and Space Sciences, Peking University No. 5 Yiheyuan Road, Haidian District Beijing, 100871 (China); Zhang, Lei, E-mail: jshept@gmail.com [SIGMA Weather Group, State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences No.1 Nanertiao, Zhongguancun, Haidian district Beijing, 100190 (China)

    2017-06-20

    The impact of an overtaking fast shock on a magnetic cloud (MC) is a pivotal process in CME–CME (CME: coronal mass ejection) interactions and CME–SIR (SIR: stream interaction region) interactions. MC with a strong and rotating magnetic field is usually deemed a crucial part of CMEs. To study the impact of a fast shock on an MC, we perform a 2.5 dimensional numerical magnetohydrodynamic simulation. Two cases are run in this study: without and with impact by fast shock. In the former case, the MC expands gradually from its initial state and drives a relatively slow magnetic reconnection with the ambient magnetic field. Analyses of forces near the core of the MC as a whole body indicates that the solar gravity is quite small compared to the Lorentz force and the pressure gradient force. In the second run, a fast shock propagates, relative to the background plasma, at a speed twice that of the perpendicular fast magnetosonic speed, catches up with and takes over the MC. Due to the penetration of the fast shock, the MC is highly compressed and heated, with the temperature growth rate enhanced by a factor of about 10 and the velocity increased to about half of the shock speed. The magnetic reconnection with ambient magnetic field is also sped up by a factor of two to four in reconnection rate as a result of the enhanced density of the current sheet, which is squeezed by the forward motion of the shocked MC.

  1. Effect of water content on specific heat capacity of porcine septum cartilage

    Science.gov (United States)

    Chae, Yongseok; Lavernia, Enrique J.; Wong, Brian J.

    2002-06-01

    The effect of water content on specific heat capacity was examined using temperature modulated Differential Scanning Calorimetry (TMDSC). This research was motivated in part by the development laser cartilage reshaping operations, which use photothermal heating to accelerate stress relaxation and shape change. Deposition of thermal energy leads to mechanical stress relaxation and redistribution of cartilage internal stresses, which may lead to a permanent shape change. The specific heat of cartilage specimens (dia: 3 mm and thickness 1-2 mm) was measured using a heating rate of 2 degree(s)C/min for conventional DSC and 2 degree(s)C/min with an amplitude 0.38-0.45 degree(s)C and a period 60-100 sec for TMDSC. The amount of water in cartilaginous tissue was determined using thermogravimetry analysis (TGA) under ambient conditions. In order to correlate changes in heat flow with alterations in cartilage mechanical behavior, dynamic mechanical temperature analysis (DMTA) was used to estimate the specific transition temperatures where stress relaxation occurs. With decreasing water content, we identified a phase transition that shifted to a higher temperature after 35-45% water content was measured. The phase transition energy increased from 0.12 J/g to 1.68 J/g after a 45% weight loss. This study is a preliminary investigation focused on understanding the mechanism of the stress relaxation of cartilage during heating. The energy requirement of such a transition estimated using TMDSC and temperature range, where cartilage shape changes likely occur, was estimated.

  2. Changes in cause-specific mortality during heat waves in central Spain, 1975-2008

    Science.gov (United States)

    Miron, Isidro Juan; Linares, Cristina; Montero, Juan Carlos; Criado-Alvarez, Juan Jose; Díaz, Julio

    2015-09-01

    The relationship between heat waves and mortality has been widely described, but there are few studies using long daily data on specific-cause mortality. This study is undertaken in central Spain and analysing natural causes, circulatory and respiratory causes of mortality from 1975 to 2008. Time-series analysis was performed using ARIMA models, including data on specific-cause mortality and maximum and mean daily temperature and mean daily air pressure. The length of heat waves and their chronological number were analysed. Data were stratified in three decadal stages: 1975-1985, 1986-1996 and 1997-2008. Heat-related mortality was triggered by a threshold temperature of 37 °C. For each degree that the daily maximum temperature exceeded 37 °C, the percentage increase in mortality due to circulatory causes was 19.3 % (17.3-21.3) in 1975-1985, 30.3 % (28.3-32.3) in 1986-1996 and 7.3 % (6.2-8.4) in 1997-2008. The increase in respiratory cause ranged from 12.4 % (7.8-17.0) in the first period, to 16.3 % (14.1-18.4) in the second and 13.7 % (11.5-15.9) in the last. Each day of heat-wave duration explained 5.3 % (2.6-8.0) increase in respiratory mortality in the first period and 2.3 % (1.6-3.0) in the last. Decadal scale differences exist for specific-causes mortality induced by extreme heat. The impact on heat-related mortality by natural and circulatory causes increases between the first and the second period and falls significantly in the last. For respiratory causes, the increase is no reduced in the last period. These results are of particular importance for the estimation of future impacts of climate change on health.

  3. Pseudogap and the specific heat of high Tc superconductors: a Hubbard model in a n-pole approximation

    International Nuclear Information System (INIS)

    Calegari, E J; Lausmann, A C; Magalhaes, S G; Chaves, C M; Troper, A

    2015-01-01

    In this work the specific heat of a two-dimensional Hubbard model, suitable to discuss high-T c superconductors (HTSC), is studied taking into account hopping to first (t) and second (t 2 ) nearest neighbors. Experimental results for the specific heat of HTSC's, for instance, the YBCO and LSCO, indicate a close relation between the pseudogap and the specific heat. In the present work, we investigate the specific heat by the Green's function method within a n-pole approximation. The specific heat is calculated on the pseudogap and on the superconducting regions. In the present scenario, the pseudogap emerges when the antiferromagnetic (AF) fluctuations become sufficiently strong. The specific heat jump coefficient Δγ decreases when the total occupation per site (n T ) reaches a given value. Such behavior of Δγ indicates the presence of a pseudogap in the regime of high occupation

  4. Pseudogap and the specific heat of high Tc superconductors: a Hubbard model in a n-pole approximation

    Science.gov (United States)

    Calegari, E. J.; Lausmann, A. C.; Magalhaes, S. G.; Chaves, C. M.; Troper, A.

    2015-03-01

    In this work the specific heat of a two-dimensional Hubbard model, suitable to discuss high-Tc superconductors (HTSC), is studied taking into account hopping to first (t) and second (t2) nearest neighbors. Experimental results for the specific heat of HTSC's, for instance, the YBCO and LSCO, indicate a close relation between the pseudogap and the specific heat. In the present work, we investigate the specific heat by the Green's function method within a n-pole approximation. The specific heat is calculated on the pseudogap and on the superconducting regions. In the present scenario, the pseudogap emerges when the antiferromagnetic (AF) fluctuations become sufficiently strong. The specific heat jump coefficient Δγ decreases when the total occupation per site (nT) reaches a given value. Such behavior of Δγ indicates the presence of a pseudogap in the regime of high occupation.

  5. Measurement and analysis of SPS kicker magnet heating and outgassing with Different Bunch Spacing

    CERN Document Server

    Barnes, M J; Cornelis, K; Ducimetière, L; Mahner, E; Papotti, G; Rumolo, G; Senaj, V; Shaposhnikova, E

    2010-01-01

    Fast kicker magnets are used to inject beam into and eject beam out of the CERN SPS accelerator ring. These kickers are generally ferrite loaded transmission line type magnets with a rectangular shaped aperture through which the beam passes. Unless special precautions are taken the impedance of the ferrite yoke can provoke significant beam induced heating, over several hours, even above the Curie temperature of the ferrite. At present the nominal bunch spacing in the SPS is 25 ns, however for an early stage of LHC operation it is preferable to have 50 ns bunch spacing. Machine Development (MD) studies have been carried out with an inter-bunch spacing of 25 ns, 50 ns or 75 ns. For some of the SPS kicker magnets the 75 ns bunch spacing resulted in considerable beam induced heating. In addition the MDs showed that 50 ns bunch spacing could result in a very rapid pressure rise in the kicker magnet and thus cause an interlock. This paper discusses the MD observations of the SPS kickers and analyses the available d...

  6. 2D heat flux pattern in ASDEX upgrade L-mode with magnetic perturbation

    Energy Technology Data Exchange (ETDEWEB)

    Faitsch, Michael; Sieglin, Bernhard; Eich, Thomas; Herrmann, Albrecht; Suttrop, Wolfgang [Max-Planck-Institute for Plasma Physics, Boltzmannstr. 2, D-85748 Garching (Germany); Collaboration: the ASDEDX Upgrade Team

    2016-07-01

    A future fusion reactor is likely to operate in high confinement mode (H-mode). This mode is associated with a periodic instability at the plasma edge that expels particles and energy. This instability is called edge localized mode (ELM). External magnetic perturbation (MP) is one technique that is thought to be able to mitigate or even suppress large ELMs in next step fusion devices such as ITER, where the ELM induced heat load for unmitigated ELMs might limit the lifetime of the divertor. Applying an external magnetic perturbation breaks the axisymmetry and leads to a 2D steady state heat flux pattern at the divertor. The ASDEX Upgrade tokamak is equipped with 16 perturbation coils, 8 above (upper row) and 8 below (lower row) the outer mid plane, toroidal equally distributed. A high resolution infra red system is measuring the heat flux at the outer target at a fixed toroidal position with a resolution of around 0.6 mm. In order to measure the 2D structure a slow rotation of the MP field was applied (1 Hz) with a toroidal mode number n=2. The differential phase between the upper and lower row was changed to investigate the effect of the alignment with the field lines at the edge. The density was varied to study the density dependence of the heat transport with applied external MP and compare it to the axisymmetric scenario.

  7. Pulsatile flow of blood and heat transfer with variable viscosity under magnetic and vibration environment

    International Nuclear Information System (INIS)

    Shit, G.C.; Majee, Sreeparna

    2015-01-01

    Unsteady flow of blood and heat transfer characteristics in the neighborhood of an overlapping constricted artery have been investigated in the presence of magnetic field and whole body vibration. The laminar flow of blood is taken to be incompressible and Newtonian fluid with variable viscosity depending upon temperature with an aim to provide resemblance to the real situation in the physiological system. The unsteady flow mechanism in the constricted artery is subjected to a pulsatile pressure gradient arising from systematic functioning of the heart and from the periodic body acceleration. The numerical computation has been performed using finite difference method by developing Crank–Nicolson scheme. The results show that the volumetric flow rate, skin-friction and the rate of heat transfer at the wall are significantly altered in the downstream of the constricted region. The axial velocity profile, temperature and flow rate increases with increase in temperature dependent viscosity, while the opposite trend is observed in the case of skin-friction and flow impedance. - Highlights: • We have investigated the pulsatile MHD flow of blood and heat transfer in arteries. • The influence of periodic body acceleration has been taken into account. • The temperature dependent viscosity of blood is considered. • The variable viscosity has an increasing effect on blood flow and heat transfer. • The overall temperature distribution enhances in the presence of magnetic field

  8. Pulsatile flow of blood and heat transfer with variable viscosity under magnetic and vibration environment

    Energy Technology Data Exchange (ETDEWEB)

    Shit, G.C., E-mail: gopal_iitkgp@yahoo.co.in; Majee, Sreeparna

    2015-08-15

    Unsteady flow of blood and heat transfer characteristics in the neighborhood of an overlapping constricted artery have been investigated in the presence of magnetic field and whole body vibration. The laminar flow of blood is taken to be incompressible and Newtonian fluid with variable viscosity depending upon temperature with an aim to provide resemblance to the real situation in the physiological system. The unsteady flow mechanism in the constricted artery is subjected to a pulsatile pressure gradient arising from systematic functioning of the heart and from the periodic body acceleration. The numerical computation has been performed using finite difference method by developing Crank–Nicolson scheme. The results show that the volumetric flow rate, skin-friction and the rate of heat transfer at the wall are significantly altered in the downstream of the constricted region. The axial velocity profile, temperature and flow rate increases with increase in temperature dependent viscosity, while the opposite trend is observed in the case of skin-friction and flow impedance. - Highlights: • We have investigated the pulsatile MHD flow of blood and heat transfer in arteries. • The influence of periodic body acceleration has been taken into account. • The temperature dependent viscosity of blood is considered. • The variable viscosity has an increasing effect on blood flow and heat transfer. • The overall temperature distribution enhances in the presence of magnetic field.

  9. Estimating thermal diffusivity and specific heat from needle probe thermal conductivity data

    Science.gov (United States)

    Waite, W.F.; Gilbert, L.Y.; Winters, W.J.; Mason, D.H.

    2006-01-01

    Thermal diffusivity and specific heat can be estimated from thermal conductivity measurements made using a standard needle probe and a suitably high data acquisition rate. Thermal properties are calculated from the measured temperature change in a sample subjected to heating by a needle probe. Accurate thermal conductivity measurements are obtained from a linear fit to many tens or hundreds of temperature change data points. In contrast, thermal diffusivity calculations require a nonlinear fit to the measured temperature change occurring in the first few tenths of a second of the measurement, resulting in a lower accuracy than that obtained for thermal conductivity. Specific heat is calculated from the ratio of thermal conductivity to diffusivity, and thus can have an uncertainty no better than that of the diffusivity estimate. Our thermal conductivity measurements of ice Ih and of tetrahydrofuran (THF) hydrate, made using a 1.6 mm outer diameter needle probe and a data acquisition rate of 18.2 pointss, agree with published results. Our thermal diffusivity and specific heat results reproduce published results within 25% for ice Ih and 3% for THF hydrate. ?? 2006 American Institute of Physics.

  10. Custom-designed Laser-based Heating Apparatus for Triggered Release of Cisplatin from Thermosensitive Liposomes with Magnetic Resonance Image Guidance.

    Science.gov (United States)

    Dou, Yannan N; Weersink, Robert A; Foltz, Warren D; Zheng, Jinzi; Chaudary, Naz; Jaffray, David A; Allen, Christine

    2015-12-13

    Liposomes have been employed as drug delivery systems to target solid tumors through exploitation of the enhanced permeability and retention (EPR) effect resulting in significant reductions in systemic toxicity. Nonetheless, insufficient release of encapsulated drug from liposomes has limited their clinical efficacy. Temperature-sensitive liposomes have been engineered to provide site-specific release of drug in order to overcome the problem of limited tumor drug bioavailability. Our lab has designed and developed a heat-activated thermosensitive liposome formulation of cisplatin (CDDP), known as HTLC, to provide triggered release of CDDP at solid tumors. Heat-activated delivery in vivo was achieved in murine models using a custom-built laser-based heating apparatus that provides a conformal heating pattern at the tumor site as confirmed by MR thermometry (MRT). A fiber optic temperature monitoring device was used to measure the temperature in real-time during the entire heating period with online adjustment of heat delivery by alternating the laser power. Drug delivery was optimized under magnetic resonance (MR) image guidance by co-encapsulation of an MR contrast agent (i.e., gadoteridol) along with CDDP into the thermosensitive liposomes as a means to validate the heating protocol and to assess tumor accumulation. The heating protocol consisted of a preheating period of 5 min prior to administration of HTLC and 20 min heating post-injection. This heating protocol resulted in effective release of the encapsulated agents with the highest MR signal change observed in the heated tumor in comparison to the unheated tumor and muscle. This study demonstrated the successful application of the laser-based heating apparatus for preclinical thermosensitive liposome development and the importance of MR-guided validation of the heating protocol for optimization of drug delivery.

  11. Magnetic fluid with high dispersion and heating performance using nano-sized Fe{sub 3}O{sub 4} platelets

    Energy Technology Data Exchange (ETDEWEB)

    Kishimoto, Mikio, E-mail: kishimoto.mikio.gb@u.tsukuba.ac.jp [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Miyamoto, Ryoichi; Oda, Tatsuya [Department of Surgery, Division of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Yanagihara, Hideto [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Ohkohchi, Nobuhiro [Department of Surgery, Division of Medicine, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan); Kita, Eiji [Institute of Applied Physics, University of Tsukuba, Tsukuba, Ibaraki 305-8573 (Japan)

    2016-01-15

    Magnetic fluid with high dispersion and heating performance was developed using 30 to 50 nm platelet Fe{sub 3}O{sub 4} particles. This fluid was prepared by mechanical dispersion in ethyl alcohol with a silane coupling agent, bonding with polyethylene glycol (PEG), and removal of aggregates formed by precipitation. The peak diameter of the resulting Fe{sub 3}O{sub 4} particles, measured by dynamic light scattering, was approximately 150 nm. The fluid exhibited a 300 W/g specific loss power (measured at 114 kHz by a 50.9 kA/m magnetic field). Distribution of the Fe{sub 3}O{sub 4} particles in tissues was observed by intravenously administrating the fluid in mice. The Fe{sub 3}O{sub 4} particles passed through the lungs, and were uniformly distributed throughout the liver and spleen. High dispersion and high heating performance were simultaneously achieved in the magnetic fluid using platelet Fe{sub 3}O{sub 4} particles surface modified with PEG. - Highlights: • Magnetic fluid with high dispersion and heating performance using Fe{sub 3}O{sub 4} particles. • Fluid prepared by mechanical dispersion, bonding with polyethylene glycol. • TEM observation and measurements of particle size distribution and specific loss power of fluid. • Observation of distribution of particles in mice tissues intravenously administrated fluid.

  12. Effect of heat treatment on interface driven magnetic properties of CoFe films

    Science.gov (United States)

    Singh, Akhilesh Kr.; Hsu, Jen-Hwa

    2017-06-01

    We report systematic studies on non-magnetic Ta underlayer and cap layer driven microstructural and magnetic properties at a wide temperature range for CoFe films. All the films were grown at room temperature and post annealed at different annealing temperatures (TA = 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C). The in-plane magnetic hysteresis (M-H) loops of 10 nm thick CoFe single layer films, grown directly on thermally oxidized Si substrate, exhibit anisotropic nature for TA above 250 °C. However, the CoFe (10 nm) films grown on the 5 nm thick Ta underlayer show reduced anisotropy. Moreover, with underlayer and cap layers (2 nm) the anisotropy is disappeared. The in-plane coercivity (HC) shows a strong variation with TA, underlayer and cap layers. HC increases significantly with Ta underlayer and cap layers. The out of plane M-H loops exhibit increase in the remanence magnetization and squareness with both Ta underlayer and cap layers due to transition of in-plane magnetization component to the out of plane direction. The atomic force microscopic observations revealed that grain/particle size and shape depend strongly on TA and Ta layers. Moreover, a large reduction in the surface roughness is observed with the Ta cap layer. The magnetic domain patterns depend on the TA, and Ta layers. However, for Ta/CoFe/Ta films no clear domains were observed for all the TA. Hence, the Ta cap layers not only protect the CoFe magnetic layer against the heat treatment, but also show a smooth surface at a wide temperature range. These results could be discussed on the basis of random anisotropy model, TA, underlayer and cap layers driven microstructure and magnetization orientation of the CoFe films.

  13. Specific heat capacities of different clayey samples obtained by differential scanning calorimetry

    International Nuclear Information System (INIS)

    Fernandez, A.M.

    2012-01-01

    Document available in extended abstract form only. The thermo-physical properties allow to calculate heat flows and to determine the thermal behaviour of the materials. Temperature influences the rates of the physical, chemical and biological reactions and processes in the soil or a material. Variations in temperature and water content in thermal, hydraulic, mechanical and geochemical processes affect the thermal properties such as density, specific heat, thermal conductivity and thermal diffusivity. Therefore, mathematical models that describe the dependence of the thermal properties on temperature and concentration are of interest to be used in computational programs applied to the modelling of coupled thermo-mechanical-hydraulic and chemical (THMC) processes. In this work, the specific heat capacity of different clayey international reference materials was determined. Differential Scanning Calorimetry (DSC) was used for such purpose. DSC is the main tool for determining the specific heat capacities of materials as a function of temperature. The specific heat capacity, c p (J/Kg.K), is a measurement of the amount of heat required to raise the temperature of a unit mass of a substance by one unit of temperature. A change in temperature, caused by a gain or a loss of heat from a material, depends on the specific heat capacity of the material. Thus, the specific heat capacity is a key and characteristic property of a material and/or substance, which should be determine accurately. The specific heat capacity is an intensive property and, unlike the thermal conductivity and thermal diffusivity, is independent of the dry density of the material. C p of the solid samples was determined by using a SETSYS Evolution 16 thermal analyser coupled to a differential scanning calorimeter (TG-DSC-DTA) from SETARAM Instrumentation. The thermal analyser system can use a heating rate from 0.01 to 100 C/min under a dynamic argon atmosphere and temperatures ranging from ambient to

  14. Calculation of cracking under pulsed heat loads in tungsten manufactured according to ITER specifications

    International Nuclear Information System (INIS)

    Arakcheev, A.S.; Skovorodin, D.I.; Burdakov, A.V.; Shoshin, A.A.; Polosatkin, S.V.; Vasilyev, A.A.; Postupaev, V.V.; Vyacheslavov, L.N.; Kasatov, A.A.; Huber, A.; Mertens, Ph; Wirtz, M.; Linsmeier, Ch; Kreter, A.; Löwenhoff, Th; Begrambekov, L.; Grunin, A.; Sadovskiy, Ya

    2015-01-01

    A mathematical model of surface cracking under pulsed heat load was developed. The model correctly describes a smooth brittle–ductile transition. The elastic deformation is described in a thin-heated-layer approximation. The plastic deformation is described with the Hollomon equation. The time dependence of the deformation and stresses is described for one heating–cooling cycle for a material without initial plastic deformation. The model can be applied to tungsten manufactured according to ITER specifications. The model shows that the stability of stress-relieved tungsten deteriorates when the base temperature increases. This proved to be a result of the close ultimate tensile and yield strengths. For a heat load of arbitrary magnitude a stability criterion was obtained in the form of condition on the relation of the ultimate tensile and yield strengths.

  15. Magnetic reconnection in plasma under inertial confinement fusion conditions driven by heat flux effects in Ohm's law.

    Science.gov (United States)

    Joglekar, A S; Thomas, A G R; Fox, W; Bhattacharjee, A

    2014-03-14

    In the interaction of high-power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. Such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. We show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2D Vlasov-Fokker-Planck code. Under such conditions, the reconnection rate is dictated by heat flows rather than Alfvènic flows. We find that this mechanism is only relevant in a high β plasma. However, the Hall parameter ωcτei can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system.

  16. Neural basis of exertional fatigue in the heat: A review of magnetic resonance imaging methods.

    Science.gov (United States)

    Tan, X R; Low, I C C; Stephenson, M C; Soong, T W; Lee, J K W

    2018-03-01

    The central nervous system, specifically the brain, is implicated in the development of exertional fatigue under a hot environment. Diverse neuroimaging techniques have been used to visualize the brain activity during or after exercise. Notably, the use of magnetic resonance imaging (MRI) has become prevalent due to its excellent spatial resolution and versatility. This review evaluates the significance and limitations of various brain MRI techniques in exercise studies-brain volumetric analysis, functional MRI, functional connectivity MRI, and arterial spin labeling. The review aims to provide a summary on the neural basis of exertional fatigue and proposes future directions for brain MRI studies. A systematic literature search was performed where a total of thirty-seven brain MRI studies associated with exercise, fatigue, or related physiological factors were reviewed. The findings suggest that with moderate dehydration, there is a decrease in total brain volume accompanied with expansion of ventricular volume. With exercise fatigue, there is increased activation of sensorimotor and cognitive brain areas, increased thalamo-insular activation and decreased interhemispheric connectivity in motor cortex. Under passive hyperthermia, there are regional changes in cerebral perfusion, a reduction in local connectivity in functional brain networks and an impairment to executive function. Current literature suggests that the brain structure and function are influenced by exercise, fatigue, and related physiological perturbations. However, there is still a dearth of knowledge and it is hoped that through understanding of MRI advantages and limitations, future studies will shed light on the central origin of exertional fatigue in the heat. © 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Temperature and air-fuel ratio dependent specific heat ratio functions for lean burned and unburned mixture

    International Nuclear Information System (INIS)

    Ceviz, M.A.; Kaymaz, I.

    2005-01-01

    The most important thermodynamic property used in heat release calculations for engines is the specific heat ratio. The functions proposed in the literature for the specific heat ratio are temperature dependent and apply at or near stoichiometric air-fuel ratios. However, the specific heat ratio is also influenced by the gas composition in the engine cylinder and especially becomes important for lean combustion engines. In this study, temperature and air-fuel ratio dependent specific heat ratio functions were derived to minimize the error by using an equilibrium combustion model for burned and unburned mixtures separately. After the error analysis between the equilibrium combustion model and the derived functions is presented, the results of the global specific heat ratio function, as varying with mass fraction burned, were compared with the proposed functions in the literature. The results of the study showed that the derived functions are more feasible at lean operating conditions of a spark ignition engine

  18. Optimizing the District Heating Primary Network from the Perspective of Economic-Specific Pressure Loss

    Directory of Open Access Journals (Sweden)

    Haichao Wang

    2017-07-01

    Full Text Available A district heating (DH system is one of the most important components of infrastructures in cold areas. Proper DH network design should balance the initial investment and the heat distribution cost of the DH network. Currently, this design is often based on a recommended value for specific pressure loss (R = ∆P/L in the main lines. This will result in a feasible network design, but probably not be optimal in most cases. The paper develops a novel optimization model to facilitate the design by considering the initial investment in the pipes and the heat distribution costs. The model will generate all possible network scenarios consisting of different series of diameters for each pipe in the flow direction of the network. Then, the annuity on the initial investment, the heat distribution cost, and the total annual cost will be calculated for each network scenario, taking into account the uncertainties of the material prices and the yearly operating time levels. The model is applied to a sample DH network and the results indicate that the model works quite well, clearly identifying the optimal network design and demonstrating that the heat distribution cost is more important than the initial investment in DH network design.

  19. Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions.

    Science.gov (United States)

    Driscoll, P E; Barnes, R

    2015-09-01

    The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the "tidal zone," where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life.

  20. Gas gap heat switch for a cryogen-free magnet system

    International Nuclear Information System (INIS)

    Barreto, J; De Sousa, P Borges; Martins, D; Bonfait, G; Catarino, I; Kar, S

    2015-01-01

    Cryogen-free superconducting magnet systems (CFMS) have become popular over the last two decades for the simple reason that the use of liquid helium is rather cumbersome and that helium is a scarce resource. Some available CFMS use a mechanical cryocooler as the magnet's cold source. However, the variable temperature insert (VTI) for some existing CFMS are not strictly cryogen-free as they are still based on helium gas circulation through the sample space. We designed a prototype of a gas gap heat switch (GGHS) that allows a thermal management of a completely cryogen-free magnet system, with no helium losses. The idea relies on a parallel cooling path to a variable temperature insert (VTI) of a magnetic properties measurement system under development at Inter-University Accelerator Centre. A Gifford-McMahon cryocooler (1.5 W @ 4.2 K) would serve primarily as the cold source of the superconducting magnet, dedicating 1 W to this cooling, under quite conservative safety factors. The remaining cooling power (0.5 W) is to be diverted towards a VTI through a controlled GGHS that was designed and built with a 80 μm gap width. The built GGHS thermal performance was measured at 4 K, using helium as the exchange gas, and its conductance is compared both with a previously developed analytical model and a finite element method. Lessons learned lead to a new and more functional prototype yet to be reported. (paper)

  1. Thermal modeling of head disk interface system in heat assisted magnetic recording

    Energy Technology Data Exchange (ETDEWEB)

    Vemuri, Sesha Hari; Seung Chung, Pil; Jhon, Myung S., E-mail: mj3a@andrew.cmu.edu [Department of Chemical Engineering and Data Storage Systems Center, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, Pennsylvania 15213 (United States); Min Kim, Hyung [Department of Mechanical System Engineering, Kyonggi University, Suwon, Gyeonggi-do 440-746 (Korea, Republic of)

    2014-05-07

    A thorough understanding of the temperature profiles introduced by the heat assisted magnetic recording is required to maintain the hotspot at the desired location on the disk with minimal heat damage to other components. Here, we implement a transient mesoscale modeling methodology termed lattice Boltzmann method (LBM) for phonons (which are primary carriers of energy) in the thermal modeling of the head disk interface (HDI) components, namely, carbon overcoat (COC). The LBM can provide more accurate results compared to conventional Fourier methodology by capturing the nanoscale phenomena due to ballistic heat transfer. We examine the in-plane and out-of-plane heat transfer in the COC via analyzing the temperature profiles with a continuously focused and pulsed laser beam on a moving disk. Larger in-plane hotspot widening is observed in continuously focused laser beam compared to a pulsed laser. A pulsed laser surface develops steeper temperature gradients compared to continuous hotspot. Furthermore, out-of-plane heat transfer from the COC to the media is enhanced with a continuous laser beam then a pulsed laser, while the temperature takes around 140 fs to reach the bottom surface of the COC. Our study can lead to a realistic thermal model describing novel HDI material design criteria for the next generation of hard disk drives with ultra high recording densities.

  2. Effect of heat sink layer on ultrafast magnetization recovery of FeCo films

    International Nuclear Information System (INIS)

    Ren, Y; Zhao, J Q; Zhang, Z Z; Jin, Q Y; Hu, H N; Zhou, S M

    2008-01-01

    For FeCo alloy thin films with Ag, Cu, Pt, Ta and Cr as heat sink layers, ultrafast demagnetization and recovery processes of transient magnetization have been studied by the time-resolved magneto-optical Kerr effect. For all samples, the ultrafast demagnetization process is accomplished within almost the same time interval of 500 fs, which is independent of the heat sink layer material and the pump fluence. The recovery rate of the FeCo film grown on the Si(1 0 0) substrate is enhanced with a heat sink layer. In addition, the recovery rate is found to be independent of the heat sink layer thickness; it decreases with increasing pump fluence. Among all heat sink layers, the sample with the Cr layer achieves the highest recovery rate because it has the same bcc structure as that of the FeCo layer and the small lattice mismatch. The sample with the Ta layer, has the largest damage threshold of pump fluence because of the highest melting point

  3. Numerical simulation of magnetic nano drug targeting in patient-specific lower respiratory tract

    Science.gov (United States)

    Russo, Flavia; Boghi, Andrea; Gori, Fabio

    2018-04-01

    Magnetic nano drug targeting, with an external magnetic field, can potentially improve the drug absorption in specific locations of the body. However, the effectiveness of the procedure can be reduced due to the limitations of the magnetic field intensity. This work investigates this technique with the Computational Fluid Dynamics (CFD) approach. A single rectangular coil generates the external magnetic field. A patient-specific geometry of the Trachea, with its primary and secondary bronchi, is reconstructed from Digital Imaging and Communications in Medicine (DICOM) formatted images, throughout the Vascular Modelling Tool Kit (VMTK) software. A solver, coupling the Lagrangian dynamics of the magnetic nanoparticles with the Eulerian dynamics of the air, is used to perform the simulations. The resistive pressure, the pulsatile inlet velocity and the rectangular coil magnetic field are the boundary conditions. The dynamics of the injected particles is investigated without and with the magnetic probe. The flow field promotes particles adhesion to the tracheal wall. The particles volumetric flow rate in both cases has been calculated. The magnetic probe is shown to increase the particles flow in the target region, but at a limited extent. This behavior has been attributed to the small particle size and the probe configuration.

  4. Theoretical approach to the phonon modes and specific heat of germanium nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Trejo, A.; López-Palacios, L.; Vázquez-Medina, R.; Cruz-Irisson, M., E-mail: irisson@ipn.mx

    2014-11-15

    The phonon modes and specific heat of Ge nanowires were computed using a first principles density functional theory scheme with a generalized gradient approximation and finite-displacement supercell algorithms. The nanowires were modeled in three different directions: [001], [111], and [110], using the supercell technique. All surface dangling bonds were saturated with Hydrogen atoms. The results show that the specific heat of the GeNWs at room temperature increases as the nanowire diameter decreases, regardless the orientation due to the phonon confinement and surface passivation. Also the phonon confinement effects could be observed since the highest optical phonon modes in the Ge vibration interval shifted to a lower frequency compared to their bulk counterparts.

  5. The effect of Ca doping on specific heat of YCoO{sub 3} cobaltate

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Rasna, E-mail: rasnathakur@yahoo.com; Thakur, Rajesh K., E-mail: thakur.rajesh2009@gmail.com; Gaur, N. K., E-mail: srl-nkgaur@yahoo.co.in [Department of Physics, Barkatullah University, Bhopal, 462026 (India)

    2016-05-06

    We have investigated the thermodynamic properties of Y{sub 1-x}Ca{sub x}CoO{sub 3} (0.0≤x≤0.1) perovskites by means of a modified rigid ion model (MRIM). The variations of specific heat at wide temperatures 1 K ≤ T ≤ 1000 K are reported. Also, the effect of lattice distortions on the elastic and thermal properties of pure and Ca doped cobaltates has been studied by an atomistic approach. Besides, we have reported bulk modulus (B), cohesive energy (ϕ), molecular force constant (f), Reststrahlen frequency (υ), Debye temperature (θ{sub D}), Gruneisen parameter (γ) and specific heat (C). It is found that the present model has a promise to predict the thermodynamic properties of other perovskites as well.

  6. Specific-heat measurements in superconducting indium-thallium alloys and the pseudopotential form factor

    International Nuclear Information System (INIS)

    Munukutla, L.V.; Cappelletti, R.L.

    1980-01-01

    Normal-state specific heats between 1 and 4.4 K and superconducting transition temperatures of pure indium and In-Tl alloys have been measured. Excellent agreement with previous results was found. N/sub bs/(0) was extracted using our γ values and Dynes's lambda values and shows a large variation. The measured variation of lambda 2 > was also obtained from Dynes's results and found to be nearly linear in spite of the large variation of N/sub bs/(0). This is shown to be a consequence of the fact that the ratio of the calculated average screened pseudopotential form factor to electron density of states, 2 /sub s/>/N/sub bs/(0), is nearly constant across the alloy series for each element. No anomaly was found in the specific heat of In/sub 0.69/Tl/sub 0.31/ at the expected martensitic transition temperature

  7. Specific-heat measurements on dilute 3He-4He mixtures

    International Nuclear Information System (INIS)

    Zeeuw, H.C.M. van der.

    1985-01-01

    The author measured the specific heat of dilute 3 He- 4 He mixtures in the concentration range from X = 1 x 10 -3 to X = 3 x 10 -3 and in the temperature range from 100 mK to 600 mK. This has been done by means of a thermal relaxation method. This method provides some interesting features and is applied, to our knowledge, for the first time to dilute 3 He- 4 He mixtures. To reach the required temperature range for our experiments a 4 He circulating 3 He- 4 He dilution refrigerator has been constructed. The results confirm the deviation of the 3 He contribution to the specific heat from the ideal Fermi gas behaviour. (Auth.)

  8. Communication: High pressure specific heat spectroscopy reveals simple relaxation behavior of glass forming molecular liquid

    DEFF Research Database (Denmark)

    Roed, Lisa Anita; Niss, Kristine; Jakobsen, Bo

    2015-01-01

    The frequency dependent specific heat has been measured under pressure for the molecular glass forming liquid 5-polyphenyl-4-ether in the viscous regime close to the glass transition. The temperature and pressure dependences of the characteristic time scale associated with the specific heat...... is compared to the equivalent time scale from dielectric spectroscopy performed under identical conditions. It is shown that the ratio between the two time scales is independent of both temperature and pressure. This observation is non-trivial and demonstrates the existence of specially simple molecular...... liquids in which different physical relaxation processes are both as function of temperature and pressure/density governed by the same underlying “inner clock.” Furthermore, the results are discussed in terms of the recent conjecture that van der Waals liquids, like the measuredliquid, comply...

  9. Specific heat of ceramic and single crystal MgB{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Junod, A.; Wang, Y.; Bouquet, F.; Sheikin, I.; Toulemonde, P.; Eskildsen, M.R.; Eisterer, M.; Weber, H.W.; Lee, S.; Tajima, S

    2003-05-15

    The two-gap structure of MgB{sub 2} gives rise to unusual thermodynamic properties which depart markedly from the single-gap BCS model, both in their temperature- and field-dependence. We report measurements of the specific heat up to 16 T on ceramic and single crystal samples, which demonstrate these effects in bulk. The low-temperature mixed-state specific heat reveals a field-dependent anisotropy, and points to the existence of unusually large vortices, in agreement with local density-of-states measurements by scanning tunneling spectroscopy. It is finally shown that a suitable irradiation process nearly doubles H{sub c2} in the bulk.

  10. The DNA electronic specific heat at low temperature: The role of aperiodicity

    Energy Technology Data Exchange (ETDEWEB)

    Sarmento, R.G. [Departamento de Física, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Mendes, G.A. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Albuquerque, E.L., E-mail: eudenilson@gmail.com [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Fulco, U.L. [Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Vasconcelos, M.S. [Escola de Ciências e Tecnologia, Universidade Federal do Rio Grande do Norte, 59072-970, Natal, RN (Brazil); Ujsághy, O. [Department of Theoretical Physics and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budapest University of Technology and Economics, Budafoki út 8, H-1521 Budapest (Hungary); Freire, V.N. [Departamento de Física, Universidade Federal do Ceará, 60455-760, Fortaleza, CE (Brazil); Caetano, E.W.S. [Instituto Federal de Educação, Ciência e Tecnologia do Ceará, 60040-531, Fortaleza, CE (Brazil)

    2012-07-16

    The electronic specific heat spectra at constant volume (C{sub V}) of a long-range correlated extended ladder model, mimicking a DNA molecule, is theoretically analyzed for a stacked array of a double-stranded structure made up from the nucleotides guanine G, adenine A, cytosine C and thymine T. The role of the aperiodicity on C{sub V} is discussed, considering two different nucleotide arrangements with increasing disorder, namely the Fibonacci and the Rudin–Shapiro quasiperiodic structures. Comparisons are made for different values of the band fillings, considering also a finite segment of natural DNA, as part of the human chromosome Ch22. -- Highlights: ► Quasiperiodic sequence to mimic the DNA nucleotides arrangement. ► Electronic tight-binding Hamiltonian model. ► Electronic density of states. ► Electronic specific heat spectra.

  11. Electron heating, magnetic field amplification, and cosmic-ray precursor length at supernova remnant shocks

    Energy Technology Data Exchange (ETDEWEB)

    Laming, J. Martin [Space Science Division, Naval Research Laboratory, Code 7684, Washington, DC 20375 (United States); Hwang, Una [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Ghavamian, Parviz [Department of Physics, Astronomy and Geosciences, Towson University, Towson, MD 21252 (United States); Rakowski, Cara, E-mail: laming@nrl.navy.mil, E-mail: Una.Hwang-1@nasa.gov, E-mail: pghavamian@towson.edu

    2014-07-20

    We investigate the observability, by direct and indirect means, of a shock precursor arising from magnetic field amplification by cosmic rays. We estimate the depth of such a precursor under conditions of nonresonant amplification, which can provide magnetic field strengths comparable to those inferred for supernova remnants. Magnetic field generation occurs as the streaming cosmic rays induce a plasma return current, and it may be quenched by either nonresonant or resonant channels. In the case of nonresonant saturation, the cosmic rays become magnetized and amplification saturates at higher magnetic fields. The precursor can extend out to 10{sup 17}-10{sup 18} cm and is potentially detectable. If resonant saturation occurs, the cosmic rays are scattered by turbulence and the precursor length will likely be much smaller. The dependence of precursor length on shock velocity has implications for electron heating. In the case of resonant saturation, this dependence is similar to that in the more familiar resonantly generated shock precursor, which when expressed in terms of the cosmic-ray diffusion coefficient kappav and shock velocity v{sub s} is kappav/v{sub s} . In the nonresonantly saturated case, the precursor length declines less quickly with increasing v{sub s} . Where precursor length proportional to 1/v{sub s} gives constant electron heating, this increased precursor length could be expected to lead to higher electron temperatures for nonresonant amplification. This should be expected at faster supernova remnant shocks than studied by previous works. Existing results and new data analysis of SN 1006 and Cas A suggest some observational support for this idea.

  12. Numerical analysis of magnetic field effects on hydro-thermal behavior of a magnetic nanofluid in a double pipe heat exchanger

    Energy Technology Data Exchange (ETDEWEB)

    Shakiba, Ali, E-mail: Shakiba7858@yahoo.com [Department of Mechanical Engineering, Mazandaran Institute of Technology, Babol (Iran, Islamic Republic of); Vahedi, Khodadad, E-mail: Khvahedi@ihu.ac.ir [Department of Mechanical Engineering, Imam Hossein University, Tehran (Iran, Islamic Republic of)

    2016-03-15

    This study attempts to numerically investigate the hydro-thermal characteristics of a ferrofluid (water and 4 vol% Fe{sub 3}O{sub 4}) in a counter-current horizontal double pipe heat exchanger, which is exposed to a non-uniform transverse magnetic field with different intensities. The magnetic field is generated by an electric current going through a wire located parallel to the inner tube and between two pipes. The single phase model and the control volume technique have been used to study the flow. The effects of magnetic field have been added to momentum equation by applying C++ codes in Ansys Fluent 14. The results show that applying this kind of magnetic field causes kelvin force to be produced perpendicular to the ferrofluid flow, changing axial velocity profile and creating a pair of vortices which leads to an increase in Nusselt number, friction factor and pressure drop. Comparing the enhancement percentage of Nusselt number, friction factor and pressure drop demonstrates that the optimum value of magnetic number for Re{sub ff}=50 is between Mn=1.33×10{sup 6} and Mn=2.37×10{sup 6}. So applying non-uniform transverse magnetic field can control the flow of ferrofluid and improve heat transfer process of double pipe heat exchanger. - Highlights: • Effect of applying non-uniform transverse magnetic field on a ferrofluid for enhancing the cooling process in a double pipe heat exchanger is investigated. • Heat exchanger is exposed to a non-uniform transverse magnetic field with different intensities. • The magnetic field is generated by an electric current going through a wire located parallel to inner tube and between two pipes. • Applying this field produces kelvin force to change axial velocity profile and creating a pair of vortices increasing Nusselt number, friction factor and pressure drop.

  13. Phonon-induced anomalous specific heat of a model nanocrystal by computer simulation

    International Nuclear Information System (INIS)

    Wang, J.; Wolf, D.; Phillpot, S.R.; Gleiter, H.

    1994-10-01

    The authors construct a simple model of a nanocrystalline material in which all the grains are the same size and shape, and in which all the grain boundaries are crystallographically identical. The authors show that the model nanocrystal has a low-temperature specific-heat anomaly similar to that seen in experiment, which arises from the presence of low-frequency phonons localized at the grain boundaries

  14. Low temperature specific heat of the spin-density-wave compound (TMTSF)2PF6

    DEFF Research Database (Denmark)

    Odin, J.; Lasjaunias, J.C.; Biljakovic, K.

    1994-01-01

    We report on specific heat measurements of the SDW compound (TMTSF)2PF6 between 2 and 25 K, performed by two different techniques. We discuss the two successive transitions which occur in this T-range : the SDW ordering transition at T = 12.1 K, and a glass transition around-3-3.5 K. The latter i...... is very dependent on the kinetics of measurements, and has all characteristic features of freezing of supercooled liquids....

  15. Susceptibility and specific heat of the Heisenberg antiferromagnet on the Kagome lattice

    International Nuclear Information System (INIS)

    Bernhard, B.H.; Canals, B.; Lacroix, C.

    2001-01-01

    The dynamic susceptibility of the S=((1)/(2)) Heisenberg antiferromagnet is calculated on the Kagome lattice by means of a Green's function decoupling scheme. The spin-spin correlation functions decrease exponentially with distance. The specific heat exhibits a single-peak structure with a T 2 dependence at low temperature and the correct high-temperature behaviour. The calculated total change in entropy indicates a ground-state entropy of 0.46 ln 2

  16. Specific heat of rare earth cobaltates RCoO{sub 3} (R = La, Pr and Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Thakur, Rasna, E-mail: rasnathakur@yahoo.com [Department of Physics, Barkatullah University, Bhopal 462026 (India); Srivastava, Archana [Department of Physics, Sri Sathya Sai College for Women, Bhopal 462024 (India); Thakur, Rajesh K.; Gaur, N.K. [Department of Physics, Barkatullah University, Bhopal 462026 (India)

    2012-03-05

    Highlights: Black-Right-Pointing-Pointer We have reported the temperature dependence (5 K {<=} T {<=} 1000 K) of the lattice contribution to the specific heat of rhombohedral LaCoO{sub 3} and orthocobaltates RCoO{sub 3} (R = Pr and Nd). Black-Right-Pointing-Pointer The strong electron phonon interactions are present in these compounds and lattice distortions can affect them substantially. Black-Right-Pointing-Pointer Thus Rigid Ion Model (RIM) is used for the first time to study the cohesive and thermal properties of the cobaltates RCoO{sub 3} with rare earth cation (R = La, Pr and Nd). Black-Right-Pointing-Pointer The values of specific heat calculated by us have shown remarkably good agreement with corresponding experimental data. Black-Right-Pointing-Pointer In addition, the results on the temperature dependence of cohesive energy ({phi}), molecular force constant (f), Reststrahlen frequency ({upsilon}), Debye temperature ({theta}{sub D}) and Gruneisen parameter ({gamma}) are also reported. - Abstract: We have reported the temperature dependence (5 K {<=} T {<=} 1000 K) of the lattice contribution to the specific heat of rhombohedral LaCoO{sub 3} and orthocobaltates RCoO{sub 3} (R = Pr and Nd). The strong electron phonon interactions are present in these compounds and lattice distortions can affect them substantially. Thus Rigid Ion Model (RIM) is used for the first time to study the cohesive and thermal properties of the cobaltates RCoO{sub 3} with rare earth cation (R = La, Pr and Nd). The values of specific heat calculated by us have shown remarkably good agreement with corresponding experimental data. In addition, the results on the temperature dependence of cohesive energy ({phi}), molecular force constant (f), Reststrahlen frequency ({upsilon}), Debye temperature ({theta}{sub D}) and Gruneisen parameter ({gamma}) are also reported.

  17. Hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements

    International Nuclear Information System (INIS)

    Michel, J.

    1969-01-01

    We have studied the hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements down to 0.3 K. In the first part we describe the apparatus used to perform our measurements. The second part is devoted to some theoretical considerations. We have studied in detail the case of praseodymium which is an exception in the rare earth series. The third part shows the results we have obtained. (author) [fr

  18. Renormalisation-group specific heat of the square lattice Potts ferromagnet

    International Nuclear Information System (INIS)

    Martin, H.O.; Tsallis, C.

    1982-01-01

    The free and internal energies and specific heat of the q-state Potts ferromagnet are discussed. A real space renormalisation group approach is presented which recovers a considerable amount of exact particular results for all dimensionalities (hypercubic lattices). The square lattice case is calculated in detail by using self-dual clusters (which provide the exact critical point for all q). Comparison with Onsager results (q=2) is satisfactory; the general tendencies for q different 2 (1 [pt

  19. Mössbauer spectroscopy, magnetization, magnetic susceptibility, and low temperature heat capacity of α-Na2NpO4

    International Nuclear Information System (INIS)

    Smith, Anna L; Hen, Amir; Magnani, Nicola; Colineau, Eric; Griveau, Jean-Christophe; Raison, Philippe E; Caciuffo, Roberto; Konings, Rudy J M; Sanchez, Jean-Pierre; Cheetham, Anthony K

    2016-01-01

    The physical and chemical properties at low temperatures of hexavalent disodium neptunate α-Na 2 NpO 4 are investigated for the first time in this work using Mössbauer spectroscopy, magnetization, magnetic susceptibility, and heat capacity measurements. The Np(VI) valence state is confirmed by the isomer shift value of the Mössbauer spectra, and the local structural environment around the neptunium cation is related to the fitted quadrupole coupling constant and asymmetry parameters. Moreover, magnetic hyperfine splitting is reported below 12.5 K, which could indicate magnetic ordering at this temperature. This interpretation is further substantiated by the existence of a λ-peak at 12.5 K in the heat capacity curve, which is shifted to lower temperatures with the application of a magnetic field, suggesting antiferromagnetic ordering. However, the absence of any anomaly in the magnetization and magnetic susceptibility data shows that the observed transition is more intricate. In addition, the heat capacity measurements suggest the existence of a Schottky-type anomaly above 15 K associated with a low-lying electronic doublet found about 60 cm −1 above the ground state doublet. The possibility of a quadrupolar transition associated with a ground state pseudoquartet is thereafter discussed. The present results finally bring new insights into the complex magnetic and electronic peculiarities of α-Na 2 NpO 4 . (paper)

  20. Evaluation of the transfer of heat from the coil of the LHC dipole magnet to Helium II

    International Nuclear Information System (INIS)

    Richter, D.; Sevred, A.; Fleiter, J.; Baudouy, B.; Devred, A.

    2007-01-01

    During operation of the Large Hadron Collider at CERN, heat will be generated inside the coils of its superconducting magnets as a consequence of ramping of magnetic field, and of the interaction of lost beam particles with the magnet mass. Heat has to be transferred from the conductor into the He II coolant and removed from the magnet environment. During the LHC R and D stage, this transfer has been extensively studied on simulated coil segments at CEA/Saclay, and by analyzing dynamic behavior of short model magnets at CERN. Owing to the importance of efficient cooling for the design of future superconducting accelerator magnets, study of heat transfer has been restored at CERN and in frame of the Next European Dipole Collaboration. The article features two recently performed works: 1) Attempt to analyse archived high ramp rate quench data of 1-m-long LHC model dipole magnets of the 2. generation. 2) Development of a method for direct measurement of heat transfer on segments of production LHC dipole magnet coils. (authors)

  1. Long-time tails of the heat-conductivity time correlation functions for a magnetized plasma - a kinetic theory approach

    NARCIS (Netherlands)

    Schoolderman, A.J.; Suttorp, L.G.

    1989-01-01

    The long-time behaviour of the longitudinal and the transverse heat conductivity time correlation functions for a magnetized one-component plasma is studied by means of kinetic theory. To that end these correlation functions, which are defined as the inverse Laplace transforms of the dynamic heat

  2. Expression of Heat Shock Proteins in Human Fibroblast Cells under Magnetic Resonant Coupling Wireless Power Transfer

    Directory of Open Access Journals (Sweden)

    Kohei Mizuno

    2015-10-01

    Full Text Available Since 2007, resonant coupling wireless power transfer (WPT technology has been attracting attention and has been widely researched for practical use. Moreover, dosimetric evaluation has also been discussed to evaluate the potential health risks of the electromagnetic field from this WPT technology based on the International Commission on Non-Ionizing Radiation Protection (ICNIRP guidelines. However, there has not been much experimental evaluation of the potential health risks of this WPT technology. In this study, to evaluate whether magnetic resonant coupling WPT induces cellular stress, we focused on heat shock proteins (Hsps and determined the expression level of Hsps 27, 70 and 90 in WI38VA13 subcloned 2RA human fibroblast cells using a western blotting method. The expression level of Hsps under conditions of magnetic resonant coupling WPT for 24 h was not significantly different compared with control cells, although the expression level of Hsps for cells exposed to heat stress conditions was significantly increased. These results suggested that exposure to magnetic resonant coupling WPT did not cause detectable cell stress.

  3. Precise determination of the heat delivery during in vivo magnetic nanoparticle hyperthermia with infrared thermography

    Science.gov (United States)

    Rodrigues, Harley F.; Capistrano, Gustavo; Mello, Francyelli M.; Zufelato, Nicholas; Silveira-Lacerda, Elisângela; Bakuzis, Andris F.

    2017-05-01

    Non-invasive and real-time monitoring of the heat delivery during magnetic nanoparticle hyperthermia (MNH) is of fundamental importance to predict clinical outcomes for cancer treatment. Infrared thermography (IRT) can determine the surface temperature due to three-dimensional heat delivery inside a subcutaneous tumor, an argument that is supported by numerical simulations. However, for precise temperature determination, it is of crucial relevance to use a correct experimental configuration. This work reports an MNH study using a sarcoma 180 murine tumor containing 3.9 mg of intratumorally injected manganese-ferrite nanoparticles. MNH was performed at low field amplitude and non-uniform field configuration. Five 30 min in vivo magnetic hyperthermia experiments were performed, monitoring the surface temperature with a fiber optical sensor and thermal camera at distinct angles with respect to the animal’s surface. The results indicate that temperature errors as large as 7~\\circ C can occur if the experiment is not properly designed. A new IRT error model is found to explain the data. More importantly, we show how to precisely monitor temperature with IRT during hyperthermia, which could positively impact heat dosimetry and clinical planning.

  4. The role of electron heat flux in guide-field magnetic reconnection

    International Nuclear Information System (INIS)

    Hesse, Michael; Kuznetsova, Masha; Birn, Joachim

    2004-01-01

    A combination of analytical theory and particle-in-cell simulations are employed in order to investigate the electron dynamics near and at the site of guide field magnetic reconnection. A detailed analysis of the contributions to the reconnection electric field shows that both bulk inertia and pressure-based quasiviscous processes are important for the electrons. Analytic scaling demonstrates that conventional approximations for the electron pressure tensor behavior in the dissipation region fail, and that heat flux contributions need to be accounted for. Based on the evolution equation of the heat flux three tensor, which is derived in this paper, an approximate form of the relevant heat flux contributions to the pressure tensor is developed, which reproduces the numerical modeling result reasonably well. Based on this approximation, it is possible to develop a scaling of the electron current layer in the central dissipation region. It is shown that the pressure tensor contributions become important at the scale length defined by the electron Larmor radius in the guide magnetic field

  5. Laser surface modification of medical grade alloys for reduced heating in a magnetic resonance imaging environment

    Energy Technology Data Exchange (ETDEWEB)

    Benafan, O., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu; Vaidyanathan, R., E-mail: othmane.benafan@nasa.gov, E-mail: raj@ucf.edu [Advanced Materials Processing and Analysis Center (AMPAC), Materials Science and Engineering, Mechanical and Aerospace Engineering, University of Central Florida, Orlando, Florida 32816 (United States); Chen, S.-Y.; Kar, A. [Laser-Advanced Materials Processing Laboratory, Center for Research and Education in Optics and Lasers (CREOL), College of Optics and Photonics, University of Central Florida, Orlando, Florida 32816 (United States)

    2015-12-15

    Nanoscale surface modification of medical grade metallic alloys was conducted using a neodymium-doped yttrium aluminum garnet laser-based dopant diffusion technique. The objective of this approach was to minimize the induction heating by reducing the absorbed radio frequency field. Such an approach is advantageous in that the dopant is diffused into the alloy and is not susceptible to detachment or spallation as would an externally applied coating, and is expected to not deteriorate the mechanical and electrical properties of the base alloy or device. Experiments were conducted using a controlled environment laser system with the ability to control laser properties (i.e., laser power, spot size, and irradiation time) and dopant characteristics (i.e., temperature, concentration, and pressure). The reflective and transmissive properties of both the doped and untreated samples were measured in a radio frequency (63.86 MHz) magnetic field using a system comprising a high power signal generator, a localized magnetic field source and sensor, and a signal analyzer. The results indicate an increase in the reflectivity of the laser-treated samples compared to untreated samples. The effect of reflectivity on the heating of the alloys is investigated through a mathematical model incorporating Maxwell’s equations and heat conduction.

  6. Effects of variable specific heat on energy transfer in a high-temperature supersonic channel flow

    Science.gov (United States)

    Chen, Xiaoping; Li, Xiaopeng; Dou, Hua-Shu; Zhu, Zuchao

    2018-05-01

    An energy transfer mechanism in high-temperature supersonic turbulent flow for variable specific heat (VSH) condition through turbulent kinetic energy (TKE), mean kinetic energy (MKE), turbulent internal energy (TIE) and mean internal energy (MIE) is proposed. The similarities of energy budgets between VSH and constant specific heat (CSH) conditions are investigated by introducing a vibrational energy excited degree and considering the effects of fluctuating specific heat. Direct numerical simulation (DNS) of temporally evolving high-temperature supersonic turbulent channel flow is conducted at Mach number 3.0 and Reynolds number 4800 combined with a constant dimensional wall temperature 1192.60 K for VSH and CSH conditions to validate the proposed energy transfer mechanism. The differences between the terms in the two kinetic energy budgets for VSH and CSH conditions are small; however, the magnitude of molecular diffusion term for VSH condition is significantly smaller than that for CSH condition. The non-negligible energy transfer is obtained after neglecting several small terms of diffusion, dissipation and compressibility related. The non-negligible energy transfer involving TIE includes three processes, in which energy can be gained from TKE and MIE and lost to MIE. The same non-negligible energy transfer through TKE, MKE and MIE is observed for both the conditions.

  7. q-deformed Einstein's model to describe specific heat of solid

    Science.gov (United States)

    Guha, Atanu; Das, Prasanta Kumar

    2018-04-01

    Realistic phenomena can be described more appropriately using generalized canonical ensemble, with proper parameter sets involved. We have generalized the Einstein's theory for specific heat of solid in Tsallis statistics, where the temperature fluctuation is introduced into the theory via the fluctuation parameter q. At low temperature the Einstein's curve of the specific heat in the nonextensive Tsallis scenario exactly lies on the experimental data points. Consequently this q-modified Einstein's curve is found to be overlapping with the one predicted by Debye. Considering only the temperature fluctuation effect(even without considering more than one mode of vibration is being triggered) we found that the CV vs T curve is as good as obtained by considering the different modes of vibration as suggested by Debye. Generalizing the Einstein's theory in Tsallis statistics we found that a unique value of the Einstein temperature θE along with a temperature dependent deformation parameter q(T) , can well describe the phenomena of specific heat of solid i.e. the theory is equivalent to Debye's theory with a temperature dependent θD.

  8. Technical specification improvements to containment heat removal and emergency core cooling systems: Final report

    International Nuclear Information System (INIS)

    Sullivan, W.P.; Ha, C.; Pentzien, D.C.; Visweswaran, S.

    1988-07-01

    This report presents the results of an analysis for technical specification improvements to the emergency core cooling systems (ECCS) and containment heat removal systems (EPRI Research Project 2142-3). The objective of this project is to further develop a reliability- and risk-based methodology to provide improvements by considering groups of surveillance test intervals and allowed out-of-service times jointly. This was done for the technical specifications for the ECCS, containment heat removal equipment, and supporting systems of a boiling water reactor plant. The project (1) developed a methodology for optimizing groups of surveillance test intervals and allowed out-of-service times jointly, (2) applied the methodology in a case study of a specific operating plant, Hatch-2, and (3) evaluated benefits of the application. The results of the case study demonstrate that beneficial technical specification improvements can be realized with application of the methodology. By tightening a small group of sensitive surveillance test intervals (STIs) and allowed out-of-service times (AOTs), a larger group of less sensitive STIs and AOTs can be extended resulting in an overall plant operating cost improvement without reducing the plant safety. The reliability- and risk-based methodology and results from this project can be effectively applied for technical specification improvements at other operating plants

  9. Increment of specific heat capacity of solar salt with SiO2 nanoparticles.

    Science.gov (United States)

    Andreu-Cabedo, Patricia; Mondragon, Rosa; Hernandez, Leonor; Martinez-Cuenca, Raul; Cabedo, Luis; Julia, J Enrique

    2014-01-01

    Thermal energy storage (TES) is extremely important in concentrated solar power (CSP) plants since it represents the main difference and advantage of CSP plants with respect to other renewable energy sources such as wind, photovoltaic, etc. CSP represents a low-carbon emission renewable source of energy, and TES allows CSP plants to have energy availability and dispatchability using available industrial technologies. Molten salts are used in CSP plants as a TES material because of their high operational temperature and stability of up to 500°C. Their main drawbacks are their relative poor thermal properties and energy storage density. A simple cost-effective way to improve thermal properties of fluids is to dope them with nanoparticles, thus obtaining the so-called salt-based nanofluids. In this work, solar salt used in CSP plants (60% NaNO3 + 40% KNO3) was doped with silica nanoparticles at different solid mass concentrations (from 0.5% to 2%). Specific heat was measured by means of differential scanning calorimetry (DSC). A maximum increase of 25.03% was found at an optimal concentration of 1 wt.% of nanoparticles. The size distribution of nanoparticle clusters present in the salt at each concentration was evaluated by means of scanning electron microscopy (SEM) and image processing, as well as by means of dynamic light scattering (DLS). The cluster size and the specific surface available depended on the solid content, and a relationship between the specific heat increment and the available particle surface area was obtained. It was proved that the mechanism involved in the specific heat increment is based on a surface phenomenon. Stability of samples was tested for several thermal cycles and thermogravimetric analysis at high temperature was carried out, the samples being stable. 65.: Thermal properties of condensed matter; 65.20.-w: Thermal properties of liquids; 65.20.Jk: Studies of thermodynamic properties of specific liquids.

  10. Heat kernel expansion for fermionic billiards in an external magnetic field

    International Nuclear Information System (INIS)

    Antoine, M.; Comtet, A.; Knecht, M.

    1989-05-01

    Using Seeley's heat kernel expansion, we compute the asymptotic density of states of the Dirac operator coupled to a magnetic field on a two dimensional manifold with boundary (fermionic billiard). Local boundary conditions compatible with vector current conservation depend on a free parameter α. It is shown that the perimeter correction identically vanishes for α = 0. In that case, the next order constant term is found to be proportional to the Euler characteristic of the manifold. These results are independent of the external magnetic field and of the shape of the billiard, provided the boundary is sufficiently smooth. For the flat circular billiard, the constant term is found to be - 1/12, in agreement with a numerical result by M.V. BERRY and R.J. MONDRAGON (1987)

  11. Heat Treatment of Iron-Carbon Alloys in a Magnetic Field (Phase 2)

    Energy Technology Data Exchange (ETDEWEB)

    Ludtka, Gerard Michael [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-11-01

    Thermomagnetic processing was shown to shift the phase transformation temperatures and therefore microstructural evolution in the high performance engine valve spring 9254 steel alloy by applying a high magnetic field during cooling. These effects would be anticipated to improve performance such as high cycle fatigue as demonstrated in prior projects. Thermomagnetic processing of gears and crank shafts was constrained by the size of the prototype equipment currently available at ORNL. However, the commercial procurement viability of production scale 9-Tesla, 16-inch diameter bore thermomagnetic processing equipment for truck idler gears up to ~11-inch diameter and potential crank shaft applications was shown, as multiple superconducting magnet manufacturing companies (in conjunction with an induction heat treating company, AjaxTOCCO Magnethermic) offered cryogen-free or cryocooler equipment designs to Cummins.

  12. Magnetic field profiles during turbulent heating in a toroidal hydrogen plasma

    International Nuclear Information System (INIS)

    Kalfsbeek, H.W.

    1978-12-01

    A description is given of the measurements of both poloidal and toroidal magnetic field components as functions of radius and time in a small turbulently heated tokamak. These measurements have been carried out with an array of miniature pick-up coils, enclosed in a quartz tube which is inserted into the plasma. The electric fields inside the plasma, as well as the parallel resistivity profiles are deduced from the measured magnetic fields. The ohmically dissipated energy is determined from the field distributions and compared with the total input energy. The experimental results are compared with the outcome of a numerical model. The consistency with information obtained from other diagnostic measurements is checked. (Auth.)

  13. Magnetic properties of doped Mn-Ga alloys made by mechanical milling and heat treatment

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Daniel R. [Department of Material Science and Engineering, Florida State University, Tallahassee, FL 32304 (United States); National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Han, Ke; Niu, Rongmei [National High Magnetic Field Laboratory, Tallahassee, FL 32310 (United States); Siegrist, Theo; Besara, Tiglet [Department of Material Science and Engineering, Florida State University, Tallahassee, FL 32304 (United States); Department of Chemical Engineering, Florida Agricultural and Mechanical University-Florida State University, Tallahassee, FL 32304 (United States)

    2016-05-15

    Mn-Ga alloys have shown hard magnetic properties, even though these alloys contain no rare-earth metals. However, much work is needed before rare-earth magnets can be replaced. We have examined the magnetic properties of bulk alloys made with partial replacement of both the Mn and Ga elements in the Mn{sub 0.8}Ga{sub 0.2} system. Bulk samples of Mn-Ga-Bi, Mn-Ga-Al, Mn-Fe-Ga and Mn-(FeB)-Ga alloys were fabricated and studied using mechanically milling and heat treatments while altering the atomic percentage of the third element between 2.5 and 20 at%. The ternary alloy exhibits all hard magnetic properties at room temperature with large coercivity. Annealed Mn-Ga-X bulk composites exhibit high coercivities up to 16.6 kOe and remanence up to 9.8 emu/g, that is increased by 115% over the binary system.

  14. Magnetic properties of doped Mn-Ga alloys made by mechanical milling and heat treatment

    Directory of Open Access Journals (Sweden)

    Daniel R. Brown

    2016-05-01

    Full Text Available Mn-Ga alloys have shown hard magnetic properties, even though these alloys contain no rare-earth metals. However, much work is needed before rare-earth magnets can be replaced. We have examined the magnetic properties of bulk alloys made with partial replacement of both the Mn and Ga elements in the Mn0.8Ga0.2 system. Bulk samples of Mn-Ga-Bi, Mn-Ga-Al, Mn-Fe-Ga and Mn-(FeB-Ga alloys were fabricated and studied using mechanically milling and heat treatments while altering the atomic percentage of the third element between 2.5 and 20 at%. The ternary alloy exhibits all hard magnetic properties at room temperature with large coercivity. Annealed Mn-Ga-X bulk composites exhibit high coercivities up to 16.6 kOe and remanence up to 9.8 emu/g, that is increased by 115% over the binary system.

  15. Structure of intermediate shocks and slow shocks in a magnetized plasma with heat conduction

    International Nuclear Information System (INIS)

    Tsai, C.L.; Wu, B.H.; Lee, L.C.

    2005-01-01

    The structure of slow shocks and intermediate shocks in the presence of a heat conduction parallel to the local magnetic field is simulated from the set of magnetohydrodynamic equations. This study is an extension of an earlier work [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002)], in which the effects of heat conduction are examined for the case that the tangential magnetic fields on the two side of initial current sheet are exactly antiparallel (B y =0). For the B y =0 case, a pair of slow shocks is formed as the result of evolution of the initial current sheet, and each slow shock consists of two parts: the isothermal main shock and the foreshock. In the present paper, cases with B y ≠0 are also considered, in which the evolution process leads to the presence of an additional pair of time-dependent intermediate shocks (TDISs). Across the main shock of the slow shock, jumps in plasma density, velocity, and magnetic field are significant, but the temperature is continuous. The plasma density downstream of the main shock decreases with time, while the downstream temperature increases with time, keeping the downstream pressure constant. The foreshock is featured by a smooth temperature variation and is formed due to the heat flow from downstream to upstream region. In contrast to the earlier study, the foreshock is found to reach a steady state with a constant width in the slow shock frame. In cases with B y ≠0, the plasma density and pressure increase and the magnetic field decreases across TDIS. The TDIS initially can be embedded in the slow shock's foreshock structure, and then moves out of the foreshock region. With an increasing B y , the propagation speed of foreshock leading edge tends to decrease and the foreshock reaches its steady state at an earlier time. Both the pressure and temperature downstreams of the main shock decrease with increasing B y . The results can be applied to the shock heating in the solar corona and

  16. Effect of microwave irradiation on selective heating behavior and magnetic separation characteristics of Panzhihua ilmenite

    International Nuclear Information System (INIS)

    Zhao, Wei; Chen, Jin; Chang, Xiaodong; Guo, Shenghui; Srinivasakannan, C.; Chen, Guo; Peng, Jinhui

    2014-01-01

    Highlights: • Microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite. • The mineral processing properties of microwave treated ilmenite were generally as good as or better than that of initial ilmenite. • The microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. - Abstract: The influences of microwave irradiation on the surface characteristics of Panzhihua ilmenite were systematically investigated. The crystal structures, surface morphology and surface chemical functional groups of ilmenite were characterized before and after microwave irradiation and magnetic separation for different microwave treatment times by using various methods, such as XRD, SEM, and FT-IR, respectively. XRD analysis showed that the microwave treated ilmenite has the strongest peaks of phase more than that of raw samples, indicates that the crystalline compound of ilmenite increased with the microwave irradiation time. SEM analysis showed the micro-cracking appeared at many grain boundaries of ilmenite after being pretreated by microwave treatment. The separations of ilmenite from gangue minerals were completed and the micro-fissure within ilmenite minerals were also formed, which could be attributed to the microwave selective heating characteristics of the different minerals and compounds, and the thermal stresses were caused by the uniform heat rate disturbed under microwave irradiation. The mineral processing results showed that the magnetic separation characteristics and properties of microwave treated ilmenite samples were better than that of microwave untreated ilmenite samples. It was concluded that microwave irradiation can be applied effectively and efficiently to the irradiation processes of Panzhihua ilmenite

  17. The real gas dynamics of the fluids of high specific heat

    International Nuclear Information System (INIS)

    Meier, G.E.A.

    1987-01-01

    The gas dynamics of real fluids show several new effects beyond the gas dynamics of ideal substances. Many of these effects rely on phase changes in the flow fields and can be explained with the help of more complicated thermal and caloric state equations of the real fluids. Complete adiabatic liquefaction and evaporation are possible for those substances whose specific heat exceeds a limit of about twenty gas constants. These fluids consisting of great molecules have so much internal energy storage capacity in their numerous vibrational degrees of freedom that the heat of evaporation can be supplied or also stored in the case of condensation. So liquefaction shock waves, which transform a gas completely or partly into a liquid, are possible. The shock front becomes thereby the surface of a liquid. Partial liquefaction with droplet condensation occurs in weaker shock waves. On the other hand a superheated liquid with high specific heat can be changed into a gas or mixture state in expansion waves or flows. (orig.)

  18. The specific heat of Cu-Al-Ni shape memory alloys

    International Nuclear Information System (INIS)

    Ruiz-Larrea, I.; Lopez-Echarri, A.; Bocanegra, E.H.; No, M.L.; San Juan, J.M.

    2006-01-01

    The specific heat of Cu 81.8 Al 13.7 Ni 4.5 (AK10) shape memory alloy has been studied by means of conventional DSC and adiabatic calorimetry techniques. The transformation temperatures and the shape of the calorimetric curves obtained by adiabatic calorimetry do not show any noticeable dependence on the temperature measurement rates, contrarily to what is observed by other calorimetric techniques. The dynamical character of the various experimental methods together with the influence of the latent heat associated to the first order character of these phase transitions are discussed. The specific heat of AK10 has been measured from 50 to 350 K which covers the phase transformation temperature range. The forward and reverse martensitic transformation peaks were found at 299.5 and 304.6 K, showing a thermal hysteresis of 5.1 deg. C. The C p accuracy can be estimated in 0.1% of C p and permits a reliable assignment of the following values to the phase transition thermodynamic functions: ΔH = 7.4 ± 0.2 J/g and ΔS = 0.025 ± 0.001 J/gK

  19. Research supporting potential modification of the NASA specification for dry heat microbial reduction of spacecraft hardware

    Science.gov (United States)

    Spry, James A.; Beaudet, Robert; Schubert, Wayne

    Dry heat microbial reduction (DHMR) is the primary method currently used to reduce the microbial load of spacecraft and component parts to comply with planetary protection re-quirements. However, manufacturing processes often involve heating flight hardware to high temperatures for purposes other than planetary protection DHMR. At present, the specifica-tion in NASA document NPR8020.12, describing the process lethality on B. atrophaeus (ATCC 9372) bacterial spores, does not allow for additional planetary protection bioburden reduction credit for processing outside a narrow temperature, time and humidity window. Our results from a comprehensive multi-year laboratory research effort have generated en-hanced data sets on four aspects of the current specification: time and temperature effects in combination, the effect that humidity has on spore lethality, and the lethality for spores with exceptionally high thermal resistance (so called "hardies"). This paper describes potential modifications to the specification, based on the data set gener-ated in the referenced studies. The proposed modifications are intended to broaden the scope of the current specification while still maintaining confidence in a conservative interpretation of the lethality of the DHMR process on microorganisms.

  20. High heat generation ability in AC magnetic field for nano-sized magnetic Y3Fe5O12 powder prepared by bead milling

    International Nuclear Information System (INIS)

    Aono, Hiromichi; Ebara, Hiroki; Senba, Ryota; Naohara, Takashi; Maehara, Tsunehiro; Hirazawa, Hideyuki; Watanabe, Yuji

    2012-01-01

    Nano-sized magnetic Y 3 Fe 5 O 12 ferrite having a high heat generation ability in an AC magnetic field was prepared by bead milling. A commercial powder sample (non-milled sample) of ca. 2.9 μm in particle size did not show any temperature enhancement in the AC magnetic field. The heat generation ability in the AC magnetic field improved with a decrease in the average crystallite size for the bead-milled Y 3 Fe 5 O 12 ferrites. The highest heat ability in the AC magnetic field was for the fine Y 3 Fe 5 O 12 powder with a 15-nm crystallite size (the samples were milled for 4 h using 0.1 mmφ beads). The heat generation ability of the excessively milled Y 3 Fe 5 O 12 samples decreased. The main reason for the high heat generation property of the milled samples was ascribed to an increase in the Néel relaxation of the superparamagnetic material. The heat generation ability was not influenced by the concentration of the ferrite powder. For the samples milled for 4 h using 0.1 mmφ beads, the heat generation ability (W g −1 ) was estimated using a 3.58×10 −4 fH 2 frequency (f/kHz) and the magnetic field (H/kA m −1 ), which is the highest reported value of superparamagnetic materials. - Highlights: ► The nano-sized Y 3 Fe 5 O 12 powder prepared by bead-milling has the highest heat generation ability in an AC magnetic field. ► The heat generation properties are ascribed to an increase in the Néel relaxation of the superparamagnetic material. ► The heat ability (W g −1 ) can be estimated using 3.58×10 −4 fH 2 (f=kHz, H=kA m −1 ). ► This is an expectable material for use in a drug delivery system for the thermal coagulation therapy of cancer tumors.

  1. Instantaneous Metabolic Cost of Walking: Joint-Space Dynamic Model with Subject-Specific Heat Rate.

    Directory of Open Access Journals (Sweden)

    Dustyn Roberts

    Full Text Available A subject-specific model of instantaneous cost of transport (ICOT is introduced from the joint-space formulation of metabolic energy expenditure using the laws of thermodynamics and the principles of multibody system dynamics. Work and heat are formulated in generalized coordinates as functions of joint kinematic and dynamic variables. Generalized heat rates mapped from muscle energetics are estimated from experimental walking metabolic data for the whole body, including upper-body and bilateral data synchronization. Identified subject-specific energetic parameters-mass, height, (estimated maximum oxygen uptake, and (estimated maximum joint torques-are incorporated into the heat rate, as opposed to the traditional in vitro and subject-invariant muscle parameters. The total model metabolic energy expenditure values are within 5.7 ± 4.6% error of the measured values with strong (R2 > 0.90 inter- and intra-subject correlations. The model reliably predicts the characteristic convexity and magnitudes (0.326-0.348 of the experimental total COT (0.311-0.358 across different subjects and speeds. The ICOT as a function of time provides insights into gait energetic causes and effects (e.g., normalized comparison and sensitivity with respect to walking speed and phase-specific COT, which are unavailable from conventional metabolic measurements or muscle models. Using the joint-space variables from commonly measured or simulated data, the models enable real-time and phase-specific evaluations of transient or non-periodic general tasks that use a range of (aerobic energy pathway similar to that of steady-state walking.

  2. Numerical renormalization group calculation of impurity internal energy and specific heat of quantum impurity models

    Science.gov (United States)

    Merker, L.; Costi, T. A.

    2012-08-01

    We introduce a method to obtain the specific heat of quantum impurity models via a direct calculation of the impurity internal energy requiring only the evaluation of local quantities within a single numerical renormalization group (NRG) calculation for the total system. For the Anderson impurity model we show that the impurity internal energy can be expressed as a sum of purely local static correlation functions and a term that involves also the impurity Green function. The temperature dependence of the latter can be neglected in many cases, thereby allowing the impurity specific heat Cimp to be calculated accurately from local static correlation functions; specifically via Cimp=(∂Eionic)/(∂T)+(1)/(2)(∂Ehyb)/(∂T), where Eionic and Ehyb are the energies of the (embedded) impurity and the hybridization energy, respectively. The term involving the Green function can also be evaluated in cases where its temperature dependence is non-negligible, adding an extra term to Cimp. For the nondegenerate Anderson impurity model, we show by comparison with exact Bethe ansatz calculations that the results recover accurately both the Kondo induced peak in the specific heat at low temperatures as well as the high-temperature peak due to the resonant level. The approach applies to multiorbital and multichannel Anderson impurity models with arbitrary local Coulomb interactions. An application to the Ohmic two-state system and the anisotropic Kondo model is also given, with comparisons to Bethe ansatz calculations. The approach could also be of interest within other impurity solvers, for example, within quantum Monte Carlo techniques.

  3. Helium flow dynamics and heat transfer in a cable in conduit conductor of superconducting magnets: a review

    International Nuclear Information System (INIS)

    Vaghela, Hitensinh; Sarkar, Biswanath; Lakhera, Vikas

    2016-01-01

    Superconducting (SC) magnets with Cable in Conduit Conductor (CICC) winding, cooled by helium at 4 K temperature are employed for many applications which require high magnetic field and high current densities. The construction of CICC aims to maintain superconductivity state by optimization of various parameters, i.e., thermal stability, ratio of normal conductor to superconductor material, mechanical strength, low hydraulic impedance, current density, magnetic field, etc. The cryogenic thermal stability of the CICC is of prime importance for the safe, stable and reliable operation of SC magnets. The prediction of thermal and hydraulic behaviour of CICC in large SC magnets is difficult due to the complex geometry, variation of fluid properties, various heat in-flux incidences over the long length of CICC and a complex heat transport phenomenon. A systematic review of the thermal and hydraulic studies of CICC has been presented in the paper highlighting the challenges and opportunities for further improvement in its design and performance. (author)

  4. Time of isothermal holding in the course of in-air heat treatment of soft magnetic Fe-based amorphous alloys and their magnetic properties

    Science.gov (United States)

    Skulkina, N. A.; Ivanov, O. A.; Pavlova, I. O.; Minina, O. A.

    2011-12-01

    On the example of soft magnetic Fe81B13Si4C2 and Fe77Ni1Si9B13 amorphous alloys, the relation between the level of magnetic properties and duration of isothermal holding in the course of heat treatment in air has been studied. The optimum temperature-dependent time τ of isothermal holding has been shown to be related to the volume fraction of domains ( V orth) with orthogonal magnetization in the initial (quenched) ribbon by equation V orth = ττ1/3. A temperature dependence of the proportionality coefficient α, which determines the degree of diffusion-process activity, has been determined. The results obtained allow us to substantially simplify the choice of optimum conditions of atmospheric heat treatment of soft magnetic Fe-based amorphous ribbons.

  5. FDTD-based Transcranial Magnetic Stimulation model applied to specific neurodegenerative disorders.

    Science.gov (United States)

    Fanjul-Vélez, Félix; Salas-García, Irene; Ortega-Quijano, Noé; Arce-Diego, José Luis

    2015-01-01

    Non-invasive treatment of neurodegenerative diseases is particularly challenging in Western countries, where the population age is increasing. In this work, magnetic propagation in human head is modelled by Finite-Difference Time-Domain (FDTD) method, taking into account specific characteristics of Transcranial Magnetic Stimulation (TMS) in neurodegenerative diseases. It uses a realistic high-resolution three-dimensional human head mesh. The numerical method is applied to the analysis of magnetic radiation distribution in the brain using two realistic magnetic source models: a circular coil and a figure-8 coil commonly employed in TMS. The complete model was applied to the study of magnetic stimulation in Alzheimer and Parkinson Diseases (AD, PD). The results show the electrical field distribution when magnetic stimulation is supplied to those brain areas of specific interest for each particular disease. Thereby the current approach entails a high potential for the establishment of the current underdeveloped TMS dosimetry in its emerging application to AD and PD. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  6. Rapid further heating of tokamak plasma by fast-rising magnetic pulse

    International Nuclear Information System (INIS)

    Inoue, N.; Nihei, H.; Yamazaki, K.; Ichimura, M.; Morikawa, J.; Hoshino, K.; Uchida, T.

    1977-01-01

    The object of the experiment was to study the rapid further heating of a tokamak plasma and its influence on confinement. For this purpose, a high-voltage theta-pinch pulse was applied to a tokamak plasma and production of a high-temperature (keV) plasma was ensured within a microsecond. The magnetic pulse is applied at the plasma current maximum parallel or antiparallel to the study toroidal field. In either case, the pulsed field quickly penetrates the plasma and the plasma resistivity estimated from the penetration time is about 100 times larger than the classical. A burst of energetic neutrals of approximately 1 μs duration was observed and the energy distribution had two components of the order of 1 keV and 0.1 keV in the antiparallel case. Doppler broadening measurement shows heating of ions to a temperature higher than 200 eV; however, the line profile is not always Maxwellian distribution. The X-rays disappear at the moment of applying the magnetic pulse and reappear about 100 μs later with an intensive burst, while both energy levels are the same (approximately 100 keV). (author)

  7. Thermal effects on transducer material for heat assisted magnetic recording application

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Rong, E-mail: Ji-Rong@dsi.a-star.edu.sg; Xu, Baoxi; Cen, Zhanhong; Ying, Ji Feng; Toh, Yeow Teck [Data Storage Institute, Agency for Science, Technology and Research (A-STAR), 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2015-05-07

    Heat Assisted Magnetic Recording (HAMR) is a promising technology for next generation hard disk drives with significantly increased data recording capacities. In HAMR, an optical near-field transducer (NFT) is used to concentrate laser energy on a magnetic recording medium to fulfill the heat assist function. The key components of a NFT are transducer material, cladding material, and adhesion material between the cladding and the transducer materials. Since transducer materials and cladding materials have been widely reported, this paper focuses on the adhesion materials between the Au transducer and the Al{sub 2}O{sub 3} cladding material. A comparative study for two kinds of adhesion material, Ta and Cr, has been conducted. We found that Ta provides better thermal stability to the whole transducer than Cr. This is because after thermal annealing, chromium forms oxide material at interfaces and chromium atoms diffuse remarkably into the Au layer and react with Au to form Au alloy. This study also provides insights on the selection of adhesion material for HAMR transducer.

  8. Heat Load Measurements on a Large Superconducting Magnet An Application of a Void Fraction Meter

    CERN Document Server

    Pengo, R; Junker, S; Passardi, Giorgio; ten Kate, H H J

    2004-01-01

    ATLAS is one of the two major experiments of the LHC project at CERN using cryogenics. The superconducting magnet system of ATLAS is composed of the Barrel Toroid (BT), two End Caps Toroids and the Central Solenoid. The BT is formed of 8 race-track superconducting dipoles, each one 25 m long and 5 m wide. A reduced scale prototype (named B0) of one of the 8 dipoles, about one third of the length, has been constructed and tested in a dedicated cryogenic facility at CERN. To simulate the final thermal and hydraulic operating conditions, the B0 was cooled by a forced flow of 4.5 K saturated liquid helium provided by a centrifugal pump of 80 g/s nominal capacity. Both static and dynamic heat loads, generated by the induced currents on the B0 casing during a slow dump or a ramp up, have been measured to verify the expected thermal budget of the entire BT. The instrument used for the heat load measurements was a Void Fraction Meter (VFM) installed on the magnet return line. The instrument constructed at CERN was ca...

  9. Application of optimal control theory to laser heating of a plasma in a solenoidal magnetic field

    International Nuclear Information System (INIS)

    Neal, R.D.

    1975-01-01

    Laser heating of a plasma column confined by a solenoidal magnetic field is studied via modern optimal control techniques. A two-temperature, constant pressure model is used for the plasma so that the temperature and density are functions of time and location along the plasma column. They are assumed to be uniform in the radial direction so that refraction of the laser beam does not occur. The laser intensity used as input to the column at one end is taken as the control variable and plasma losses are neglected. The localized behavior of the plasma heating dynamics is first studied and conventional optimal control theory applied. The distributed parameter optimal control problem is next considered with minimum time to reach a specified final ion temperature criterion as the objective. Since the laser intensity can only be directly controlled at the input end of the plasma column, a boundary control situation results. The problem is unique in that the control is the boundary value of one of the state variables. The necessary conditions are developed and the problem solved numerically for typical plasma parameters. The problem of maximizing the space-time integral of neutron production rate in the plasma is considered for a constant distributed control problem where the laser intensity is assumed fixed at maximum and the external magnetic field is taken as a control variable

  10. Physical Properties and Specific Heat Capacity of Tamarind (Tamarindus indica Seed

    Directory of Open Access Journals (Sweden)

    A. Dauda

    2017-04-01

    Full Text Available This study investigated the effect of moisture content on physical properties and specific heat capacity of Tamarindus indica seed. Physical properties investigated were axial dimensions, one thousand seed weight, bulk and true densities, porosity, roundness and sphericity, surface area, angle of repose and static coefficient of friction. The thermal property determined was the specific heat. These properties of Tamarindus indica seed were investigated within the moisture content range of 7.55 - 10.47% (d.b. The length, width and thickness increased from 9.979 to 10.634mm, 8.909 to 10.089mm and 5.039 to 5.658mm, respectively in the above moisture range. One thousand seed weight, surface area, seed volume, true density and porosity, increased from 388.4 to 394.8g, 86.916 to 87.58cm2, 0.353 to 0.366cm3, 1217.5 to 1287.00kg/m3 and 28.22 to 33.87%, respectively, as moisture content increased in the above range, while bulk density decreased from 873.9 to 851.4kg/m3. Roundness and sphericity, and angle of repose also increased from 41 to 42.4% and 73.7 to 76.3% and 36.1 to 38.93o, respectively. Specific heat capacity values increased linearly from 589.00J/kgK to 638.61 J/kgK in the above moisture range.

  11. Competing pseudogap and impurity effects on the normal-state specific heat properties of cuprate superconductors

    Science.gov (United States)

    Dzhumanov, S.; Karimboev, E. X.

    2014-07-01

    In this paper, we show that the pseudogap in the excitation spectra of high-Tc cuprates together with the impurity phase and charge inhomogeneity plays key roles in determining the essential features of their anomalous specific heat properties observed above Tc. We consider the doped cuprate superconductor as a multi-carrier model system (which consists of intrinsic and extrinsic polarons and pre-formed bosonic Cooper pairs) and study the competing pseudogap and impurity effects on the normal-state electronic specific heat of high-Tc cuprates taking into account charge inhomogeneities. We argue that unconventional electron-phonon interactions are responsible for the precursor Cooper pairing in the polaronic band below a mean-field temperature T∗ and the existence of a pseudogap above Tc in the cuprates. The electronic specific heat Ce(T) of doped cuprates below T∗ is calculated taking into account three contributions coming from the excited components of Cooper pairs, the ideal Bose-gas of incoherent Cooper pairs and the unpaired carriers in the impurity band. Above T∗, two contributions to Ce(T) coming from the unpaired intrinsic and extrinsic polarons are calculated within the two-component degenerate Fermi-gas model. By comparing our results with the experimental Ce(T) data obtained for La- and Y-based cuprates, we find that the observed behaviors of Ce(T) (below and above T∗) are similar to the calculated results for Ce(T) and the BCS-type jumps of Ce(T) at T∗ may be depressed by the impurity effects and may become more or less pronounced BCS-type anomalies in Ce(T) .

  12. Effect of magnetic fields on the Kondo insulator CeRhSb: Magnetoresistance and high-field heat capacity measurements

    International Nuclear Information System (INIS)

    Malik, S.K.; Menon, L.; Pecharsky, V.K.; Gschneidner, K.A. Jr.

    1997-01-01

    The compound CeRhSb is a mixed valent Ce-based compound which shows a gap in the electronic density of states at low temperatures. The gap manifests by a rise in electrical resistivity below about 8 K from which the gap energy is estimated to be about 4 K. We have carried out heat capacity measurements on this compound in various applied fields up to 9.85 T. The magnetic contribution to the heat capacity, ΔC, is found to have a maximum in ΔC/T vs T at 10 K, below which ΔC/T is linear with T. This is attributed to the fact that below this temperature, in the gapped state, the electronic density of states decreases linearly with decreasing temperature. On application of a magnetic field, the electronic specific heat coefficient γ in the gapped state increases by ∼4mJ/molK 2 . The maximum in ΔC/T vs T is observed in all fields, which shifts to lower temperatures ∼1K at 5.32 T and raises again at 9.85 T to about the same values as at H=0T. This suggests that the gap exists for all fields up to 9.85 T. Above 10 K, in the mixed-valent state, ΔC/T vs T decreases with increasing temperature in zero field. There is hardly any effect of application of field in the mixed-valent state. We have also carried out magnetoresistance measurements on CeRhSb up to fields of 5.5 T at 2, 4.5, 10, 20, and 30 K. The magnetoresistance in CeRhSb is positive at temperatures of 4.5 K and above, in applied fields up to 5.5 T. At 5.5 T, the magnetoresistance is maximum at 4.5 K (6%) and decreases with increasing temperature. The observation of the maximum is consistent with the observation of a maximum in ΔC/T vs T and is due to a change in the density of states. At a temperature of 2 K, a negative magnetoresistance is observed for magnetic fields greater than ∼3.5T which suggests reduction in the gap. copyright 1997 The American Physical Society

  13. Magnetic flux and heat losses by diffusive, advective, and Nernst effects in MagLIF-like plasma

    International Nuclear Information System (INIS)

    Velikovich, A. L.; Giuliani, J. L.; Zalesak, S. T.

    2014-01-01

    The MagLIF approach to inertial confinement fusion involves subsonic/isobaric compression and heating of a DT plasma with frozen-in magnetic flux by a heavy cylindrical liner. The losses of heat and magnetic flux from the plasma to the liner are thereby determined by plasma advection and gradient-driven transport processes, such as thermal conductivity, magnetic field diffusion and thermomagnetic effects. Theoretical analysis based on obtaining exact self-similar solutions of the classical collisional Braginskii's plasma transport equations in one dimension demonstrates that the heat loss from the hot plasma to the cold liner is dominated by the transverse heat conduction and advection, and the corresponding loss of magnetic flux is dominated by advection and the Nernst effect. For a large electron Hall parameter ω e τ e effective diffusion coefficients determining the losses of heat and magnetic flux are both shown to decrease with ω e τ e as does the Bohm diffusion coefficient, which is commonly associated with low collisionality and two-dimensional transport. This family of exact solutions can be used for verification of codes that model the MagLIF plasma dynamics

  14. Specific feature of magnetooptical images of stray fields of magnets of various geometrical shapes

    Science.gov (United States)

    Ivanov, V. E.; Koveshnikov, A. V.; Andreev, S. V.

    2017-08-01

    Specific features of magnetooptical images (MOIs) of stray fields near the faces of prismatic hard magnetic elements have been studied. Attention has primarily been focused on MOIs of fields near faces oriented perpendicular to the magnetic moment of hard magnetic elements. With regard to the polar sensitivity, MOIs have practically uniform brightness and geometrically they coincide with the figures of the bases of the elements. With regard to longitudinal sensitivity, MOIs consist of several sectors, the number of which is determined by the number of angles of the image. Each angle is divided by the bisectrix into two sectors of different brightnesses; therefore, the MOI of a triangular magnet consists of three sectors. A rectangle consists of four sectors separated by the bisectrices of the interior angles. In all types of figures, these lines converge at the center of the figure and form a singular point of the source or sink type.

  15. Analysis of the phonon surface specific heat using Green function techniques

    International Nuclear Information System (INIS)

    Carrico, A.S.; Albuquerque, E.L.

    1980-01-01

    Green functions are derived for the displacement associated with acoustic vibrations in isotropic elastic media and used to evaluate the surface specific heat in the harmonic approximation. We consider only the low-temperature limit case since, provided K B 1/h is very samll, we can replace the dispersion relation for the three acoustic branches by its long-wavelenghts form. The contributions of surface elastic waves ot the Rayleigh and Love types are pointed out and their features discussed. The nature of the result and their relations to previous work in this field is also presented and discussed. (author) [pt

  16. Pressure dependence of the specific heat of heavy-fermion YbCu4.5

    International Nuclear Information System (INIS)

    Amato, A.; Fisher, R.A.; Phillips, N.E.; Jaccard, D.; Walker, E.

    1990-03-01

    The specific heat of a polycrystalline sample of YbCu 4.5 has been measured between 0.3 and 20K at pressures to 8.2 kbar. Unlike cerium-based heavy-fermion compounds, an increase of C/T is observed with increasing pressure, with the linear term enhanced by about 16% at 8.2 kbar. Above 7K, (∂C/∂P) T is negative. The nuclear contribution observed at P = 0 is increased by roughly a factor of two at 8.2 kbar. 7 refs., 3 figs

  17. Analysis of the phonon surface specific heat using Green function techniques

    International Nuclear Information System (INIS)

    Silva Carrico, A. da; Albuquerque, E.L. de

    1981-01-01

    Green functions are derived for the displacement associated with acoustic vibrations in isotropic elastic media and used to evaluate the surface specific heat in the harmonic approximation. Only the low-temperature limit case is considered since, provided K sub(B) T/h is very small, the dispersion relation for the three acoustic branches can be replaced by its long-wavelenght form. The contributions of surface elastic waves of the Rayleigh and Love types are pointed out and their features discussed. The nature of the result and their relations to previous work in this field is also presented and discussed. (Author) [pt

  18. Specific heat of Ginzburg-Landau fields in the n-1 expansion

    International Nuclear Information System (INIS)

    Bray, A.J.

    1975-01-01

    The n -1 expansion for the specific heat C/subv/ of the n-component Ginzburg-Landau model is discussed in terms of an n -1 expansion for the irreducible polarization. In the low-temperature limit, each successive term of the latter expansion diverges more strongly than the last, invalidating a truncation of this series at any finite order in 1/n. The most divergent terms in each order are identified and summed. The results provide justification for the usual truncated expansions for C/subv/

  19. Dynamic properties of silica aerogels as deduced from specific-heat and thermal-conductivity measurements

    DEFF Research Database (Denmark)

    Bernasconi, A.; Sleator, T.; Posselt, D.

    1992-01-01

    The specific heat C(p) and the thermal conductivity lambda of a series of base-catalyzed silica aerogels have been measured at temperatures between 0.05 and 20 K. The results confirm that the different length-scale regions observed in the aerogel structure are reflected in the dynamic behavior of...... SiO2 are most likely not due to fractal behavior....... the possibility of two spectral dimensions characterizing the fracton modes. Our data imply important differences between the physical mechanisms dominating the low-temperature behavior of aerogels and dense glasses, respectively. From our analysis we also conclude that the low-temperature properties of amorphous...

  20. Effects of phonon dimensionality in the specific heat of multiwall carbon nanotubes at low temperatures

    International Nuclear Information System (INIS)

    Jorge, Guillermo A; Bekeris, V; Acha, C; Escobar, M M; Goyanes, S; Zilli, D; Cukierman, A L; Candal, R J

    2009-01-01

    We have measured the specific heat at constant pressure, C p , of three different samples of multiwall carbon nanotubes (MWNT). For all samples, C p departs from a graphitic behavior at T p measurements show a temperature threshold from a linear regime for intermediate temperature to a higher-order power law for low temperatures. Moreover, it was found that this crossover only depends on the internal structure of the individual MWNT and not on the spatial order of the MWNT within a bundle.