Holographic heat current as Noether current

We reviewed some recent ideas to improve the efficiency and power output of thermoelectric nano-devices. We focused on two essentially independent aspects: (i) increasing the charge current by taking advantage of an interplay between the material and the thermodynamic parameters, which is only available in the non-linear regime; and (ii) decreasing the heat current by using nanowires with surface disorder, which helps excite localized phonons at random positions that can strongly scatter the propagating phonons carrying the thermal current.

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A Thermal Transport Study of Branched Carbon Nanotubes with Cross and T-Junctions

Applied Sciences ◽

10.3390/app11135933 ◽

2021 ◽

Vol 11 (13) ◽

pp. 5933

Author(s):

Wei-Jen Chen ◽

I-Ling Chang

Keyword(s):

Heat Transfer ◽

Carbon Nanotubes ◽

Thermal Management ◽

Thermal Transport ◽

Topological Defects ◽

Branch Length ◽

Phonon Transport ◽

Heat Current ◽

Transport Mechanisms ◽

Non Equilibrium Molecular Dynamics

This study investigated the thermal transport behaviors of branched carbon nanotubes (CNTs) with cross and T-junctions through non-equilibrium molecular dynamics (NEMD) simulations. A hot region was created at the end of one branch, whereas cold regions were created at the ends of all other branches. The effects on thermal flow due to branch length, topological defects at junctions, and temperature were studied. The NEMD simulations at room temperature indicated that heat transfer tended to move sideways rather than straight in branched CNTs with cross-junctions, despite all branches being identical in chirality and length. However, straight heat transfer was preferred in branched CNTs with T-junctions, irrespective of the atomic configuration of the junction. As branches became longer, the heat current inside approached the values obtained through conventional prediction based on diffusive thermal transport. Moreover, directional thermal transport behaviors became prominent at a low temperature (50 K), which implied that ballistic phonon transport contributed greatly to directional thermal transport. Finally, the collective atomic velocity cross-correlation spectra between branches were used to analyze phonon transport mechanisms for different junctions. Our findings deeply elucidate the thermal transport mechanisms of branched CNTs, which aid in thermal management applications.

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Quantum control of excitons for reversible heat transfer

Communications Physics ◽

10.1038/s42005-019-0215-8 ◽

2019 ◽

Vol 2 (1) ◽

Author(s):

Conor N. Murphy ◽

Paul R. Eastham

Keyword(s):

Heat Transfer ◽

Quantum Dot ◽

Quantum Control ◽

Heat Engine ◽

Laser Pulses ◽

Heat Current ◽

Light Emitting ◽

Laser Dressing ◽

Working Medium ◽

Heat Transfers

Abstract Lasers, photovoltaics, and thermoelectrically-pumped light emitting diodes are thermodynamic machines which use excitons (electron-hole pairs) as the working medium. The heat transfers in such devices are highly irreversible, leading to low efficiencies. Here we predict that reversible heat transfers between a quantum-dot exciton and its phonon environment can be induced by laser pulses. We calculate the heat transfer when a quantum-dot exciton is driven by a chirped laser pulse. The reversibility of this heat transfer is quantified by the efficiency of a heat engine in which it forms the hot stroke, which we predict to reach 95% of the Carnot limit. This performance is achieved by using the time-dependent laser-dressing of the exciton to control the heat current and exciton temperature. We conclude that reversible heat transfers can be achieved in excitonic thermal machines, allowing substantial improvements in their efficiency.

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Anomalous Hall Heat Current and Nernst Effect in theCuCr2Se4−xBrxFerromagnet

Physical Review Letters ◽

10.1103/physrevlett.93.226601 ◽

2004 ◽

Vol 93 (22) ◽

Cited By ~ 90

Author(s):

Wei-Li Lee ◽

S. Watauchi ◽

V. L. Miller ◽

R. J. Cava ◽

N. P. Ong

Keyword(s):

Heat Current ◽

Nernst Effect

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Problems of Cold-Bent Notched C-Shaped Profile Members

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.941-944.1871 ◽

2014 ◽

Vol 941-944 ◽

pp. 1871-1875 ◽

Cited By ~ 27

Author(s):

Nikolay I. Vatin ◽

Tatiana Nazmeeva ◽

Roman Guslinscky

Keyword(s):

Bearing Capacity ◽

Cross Sections ◽

Experimental Investigations ◽

Heat Current ◽

Thermal Profile ◽

Engineering Structures ◽

Normative Documents ◽

Steel Members ◽

Global Buckling ◽

Stability Of Structures

Nowadays cold bent steel thermal сold-bent С-profile is widely used in building construction but we still have some little studied questions in the fields of thermal conductivity, air permeability, resistibility and corrosion behavior of the profile. Cold-bent notched С-profile is used for interior exterior panel members. Lengthwise notches made chequerwise in the profile walls increase the distance of heat flow and decrease heat conductivity and eliminate cold bridges that is why the profile is called “thermal profile”. Cold-bent profile made by cold bending requires alternate approach when engineering structures are designed and maintained. The approach means thin walls’ and the profile special form’ impact on the bearing capacity and stability of the structures should be taken into account. In spite of the wide use of cold-bent notched C-profile in building frameworks, we see lack of information on how the notches influence the bearing capacity and stability of structures. There are no official normative documents on calculation and designing of cold-bent notched profile structures. We carry out theoretical and experimental investigations on global buckling and bearing capacity of steel members of C-shaped notched profiles of different cross-sections area. We carry out theoretical and experimental investigations on heat current passing through the thermal profile structure is held with the use of testing bed.

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On the Possibility of Detecting Phonon Drag Due to an Electronic Heat Current

Thermal Conductivity 14 ◽

10.1007/978-1-4899-3751-3_21 ◽

1976 ◽

pp. 121-126 ◽

Cited By ~ 1

Author(s):

R. Fletcher

Keyword(s):

Heat Current ◽

Phonon Drag ◽

Electronic Heat

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ABELIAN ANOMALIES IN NONLOCAL REGULARIZATION

International Journal of Modern Physics A ◽

10.1142/s0217751x94001801 ◽

1994 ◽

Vol 09 (26) ◽

pp. 4549-4564 ◽

Cited By ~ 6

Author(s):

M.A. CLAYTON ◽

L. DEMOPOULOS ◽

J.W. MOFFAT

Keyword(s):

Path Integral ◽

Invariant Theory ◽

Axial Anomaly ◽

Regularization Scheme ◽

Integral Measure ◽

Nonlocal Regularization ◽

Noether Current

The nonlocal regularization of QED is shown to possess an axial anomaly of the same form as other regularization schemes. The Noether current is explicitly constructed and the symmetries are shown to be violated, whereas the identities constructed when one properly considers the contribution from the path integral measure are respected. We also discuss the merits and new features of the regularization scheme, as well as the barrier to quantizing the fully gauged chiral-invariant theory.

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Heat current rectification in segmented XXZ chains

Physical Review E ◽

10.1103/physreve.99.032136 ◽

2019 ◽

Vol 99 (3) ◽

Cited By ~ 12

Author(s):

Vinitha Balachandran ◽

Giuliano Benenti ◽

Emmanuel Pereira ◽

Giulio Casati ◽

Dario Poletti

Keyword(s):

Heat Current ◽

Current Rectification

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Optimal Power and Efficiency of Multi-Stage Endoreversible Quantum Carnot Heat Engine with Harmonic Oscillators at the Classical Limit

Entropy ◽

10.3390/e22040457 ◽

2020 ◽

Vol 22 (4) ◽

pp. 457 ◽

Cited By ~ 4

Author(s):

Zewei Meng ◽

Lingen Chen ◽

Feng Wu

Keyword(s):

Classical Limit ◽

Heat Engine ◽

Combined Cycle ◽

Harmonic Oscillators ◽

Total Power ◽

Cycle Period ◽

Carnot Cycle ◽

Heat Current ◽

Operating Modes ◽

Multi Stage

At the classical limit, a multi-stage, endoreversible Carnot cycle model of quantum heat engine (QHE) working with non-interacting harmonic oscillators systems is established in this paper. A simplified combined cycle, where all sub-cycles work at maximum power output (MPO), is analyzed under two types of combined form: constraint of cycle period or constraint of interstage heat current. The expressions of power and the corresponding efficiency under two types of combined constrains are derived. A general combined cycle, in which all sub-cycles run at arbitrary state, is further investigated under two types of combined constrains. By introducing the Lagrangian function, the MPO of two-stage combined QHE with different intermediate temperatures is obtained, utilizing numerical calculation. The results show that, for the simplified combined cycle, the total power decreases and heat exchange from hot reservoir increases under two types of constrains with the increasing number (N) of stages. The efficiency of the combined cycle decreases under the constraints of the cycle period, but keeps constant under the constraint of interstage heat current. For the general combined cycle, three operating modes, including single heat engine mode at low “temperature” (SM1), double heat engine mode (DM) and single heat engine mode at high “temperature” (SM2), appear as intermediate temperature varies. For the constraint of cycle period, the MPO is obtained at the junction of DM mode and SM2 mode. For the constraint of interstage heat current, the MPO keeps constant during DM mode, in which the two sub-cycles compensate each other.

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