ScholarBank@NUShttps://scholarbank.nus.edu.sgThe DSpace digital repository system captures, stores, indexes, preserves, and distributes digital research material.Tue, 22 Oct 2019 12:43:51 GMT2019-10-22T12:43:51Z5071- Temperature dependence of thermal conductivity in 1D nonlinear latticeshttps://scholarbank.nus.edu.sg/handle/10635/98223Title: Temperature dependence of thermal conductivity in 1D nonlinear lattices
Authors: Li, N.; Li, B.
Abstract: We examine the temperature dependence of thermal conductivity of one-dimensional nonlinear (anharmonic) lattices with and without on-site potential. It is found from computer simulation that the heat conductivity depends on temperature via the strength of nonlinearity. Based on this correlation, we make a conjecture in the effective phonon theory that the mean-free-path of the effective phonon is inversely proportional to the strength of nonlinearity. We demonstrate analytically and numerically that the temperature behavior of the heat conductivity κ 1/T is not universal for 1D harmonic lattices with a small nonlinear perturbation. The computer simulations of temperature dependence of heat conductivity in general 1D nonlinear lattices are in good agreement with our theoretic predictions. Possible experimental tests are discussed. © Europhysics Letters Association.
Tue, 01 May 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/982232007-05-01T00:00:00Z
- Colloquium: Phononics: Manipulating heat flow with electronic analogs and beyondhttps://scholarbank.nus.edu.sg/handle/10635/96016Title: Colloquium: Phononics: Manipulating heat flow with electronic analogs and beyond
Authors: Li, N.; Ren, J.; Wang, L.; Zhang, G.; Hänggi, P.; Li, B.
Abstract: The form of energy termed heat that typically derives from lattice vibrations, i.e., phonons, is usually considered as waste energy and, moreover, deleterious to information processing. However, in this Colloquium, an attempt is made to rebut this common view: By use of tailored models it is demonstrated that phonons can be manipulated similarly to electrons and photons, thus enabling controlled heat transport. Moreover, it is explained that phonons can be put to beneficial use to carry and process information. In the first part ways are presented to control heat transport and to process information for physical systems which are driven by a temperature bias. In particular, a toolkit of familiar electronic analogs for use of phononics is put forward, i.e., phononic devices are described which act as thermal diodes, thermal transistors, thermal logic gates, and thermal memories. These concepts are then put to work to transport, control, and rectify heat in physically realistic nanosystems by devising practical designs of hybrid nanostructures that permit the operation of functional phononic devices; the first experimental realizations are also reported. Next, richer possibilities to manipulate heat flow by use of time-varying thermal bath temperatures or various other external fields are discussed. These give rise to many intriguing phononic nonequilibrium phenomena such as, for example, the directed shuttling of heat, geometrical phase-induced heat pumping, or the phonon Hall effect, which may all find their way into operation with electronic analogs. © 2012 American Physical Society.
Tue, 17 Jul 2012 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/960162012-07-17T00:00:00Z
- Parameter-dependent thermal conductivity of one-dimensional 4 latticehttps://scholarbank.nus.edu.sg/handle/10635/97487Title: Parameter-dependent thermal conductivity of one-dimensional 4 lattice
Authors: Li, N.; Li, B.
Abstract: We examine the thermal conductivity of a one-dimensional 4 lattice with strong on-site harmonic potential. The expression for the thermal conductivity in terms of different parameters is derived from the effective phonon theory. Numerical calculations using nonequilibrium molecular dynamics are compared with the predictions of the effective phonon theory and the theory of the Peierls-Boltzmann transport equation. It is found that the numerical results are consistent with the prediction of the effective phonon theory in the intermediate parameter range and approach the predictions of Peierls-Boltzmann transport theory in the strongly pinned limit. © 2007 The American Physical Society.
Fri, 13 Jul 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/974872007-07-13T00:00:00Z
- Thermal conductivity of one-dimensional lattices with self-consistent heat baths: A heuristic derivationhttps://scholarbank.nus.edu.sg/handle/10635/98350Title: Thermal conductivity of one-dimensional lattices with self-consistent heat baths: A heuristic derivation
Authors: Li, N.; Li, B.
Abstract: We derive the thermal conductivities of one-dimensional harmonic and anharmonic lattices with selfconsistent heat baths from the single-mode relaxation time (SMRT) approximation. For harmonic lattice, we obtain the same result as previous works. However, our approach is heuristic and reveals phonon picture explicitly within the heat transport process. The results for harmonic and anharmonic lattices are compared with numerical calculations from Green-Kubo formula. The consistency between derivation and simulation strongly supports that effective (renormalized) phonons are energy carriers in anharmonic lattices although there exist some other excitations such as solitons and breathers. © 2009 The Physical Society of Japan.
Wed, 01 Apr 2009 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983502009-04-01T00:00:00Z
- Ratcheting heat flux against a thermal biashttps://scholarbank.nus.edu.sg/handle/10635/97759Title: Ratcheting heat flux against a thermal bias
Authors: Li, N.; Hänggi, P.; Li, B.
Abstract: Merely rocking the temperature in one heat bath can direct a steady heat flux from cold to hot against a (time-averaged) non-zero thermal bias in stylized nonlinear lattice junctions that are sandwiched between two heat baths. Likewise, for an average zero-temperature difference between the two contacts a net, ratchet-like heat flux emerges. Computer simulations show that this very heat flux can be manipulated and even reversed by suitably tailoring the frequency (≲100 MHz) of the alternating-temperature field. © Europhysics Letters Association. 2008.
Tue, 01 Jan 2008 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/977592008-01-01T00:00:00Z
- Thermal rectification and negative differential thermal resistance in lattices with mass gradienthttps://scholarbank.nus.edu.sg/handle/10635/98362Title: Thermal rectification and negative differential thermal resistance in lattices with mass gradient
Authors: Yang, N.; Li, N.; Wang, L.; Li, B.
Abstract: We study thermal properties of one-dimensional (1D) harmonic and anharmonic lattices with a mass gradient. It is found that a temperature gradient can be built up in the 1D harmonic lattice with a mass gradient due to the existence of gradons. The heat flow is asymmetric in anharmonic lattices with a mass gradient. Moreover, in a certain temperature region, negative differential thermal resistance is observed. Possible applications in constructing thermal rectifiers and thermal transistors by using the graded material are discussed. © 2007 The American Physical Society.
Tue, 24 Jul 2007 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/983622007-07-24T00:00:00Z
- Effective phonons in anharmonic lattices: Anomalous vs. normal heat conductionhttps://scholarbank.nus.edu.sg/handle/10635/96354Title: Effective phonons in anharmonic lattices: Anomalous vs. normal heat conduction
Authors: Li, N.; Tong, P.; Li, B.
Abstract: We study heat conduction in one-dimensional (1D) anharmonic lattices analytically and numerically by using an effective phonon theory. It is found that every effective phonon mode oscillates quasi-periodically. By weighting the power spectrum of the total heat flux in the Debye formula, we obtain a unified formalism that can explain anomalous heat conduction in momentum conserved lattices without on-site potential and normal heat conduction in lattices with on-site potential. Our results agree very well with numerical ones for existing models such as the Fermi-Pasta-Ulam model, the Prenkel-Kontorova model and the Φ4 model etc. © EDP Sciences.
Sat, 01 Jul 2006 00:00:00 GMThttps://scholarbank.nus.edu.sg/handle/10635/963542006-07-01T00:00:00Z