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91.
Bangdao ChenHongzhong Liu Hongtao WangFan Fan Li WangYucheng Ding Bingheng Lu 《Applied Surface Science》2011,257(21):9125-9128
Significant emission current enhancement has been achieved for surface conduction electron emitter, due to the special three-dimensional nanocrack structure fabricated by the thermal shock process. The three-dimensional configuration strongly changed the electric field distribution and controlled the emission electron trajectory. Thermal shock treatment was also used to increase the edge roughness of the nanocrack and thereby dramatically improved the field emission characteristics. Stable and uniform electron emission was observed with turn-on voltage of 150 V. The surface conduction current of 400 μA for 6 cells was obtained with the detector voltage of 1 kV and the gap voltage of 170 V. 相似文献
92.
Yuan MoWei-Qing Huang Gui-Fang Huang Wangyu Hu Ling-Ling Wang Anlian Pan 《Physics letters. A》2011,375(19):2000-2006
We investigate the ballistic phonon transport through a Fibonacci array of acoustic nanocavities in a narrow constriction of a semiconductor nanowire at low temperatures. It is found that the transmission spectrum of such a system consists of quasiband gaps and narrow resonances caused by the coupling of phonon waves. Both phonon transmission and thermal conductance exhibit the similarity due to the Fibonacci sequence structure. The similarity is sensitive to the number n and parameters of nanocavities. The results are compared with those in a periodic acoustic nanocavities. 相似文献
93.
Masuo Suzuki 《Physica A》2011,390(11):1904-1916
94.
Hongnian Li Yabo Xu Shining Bao Haiyang Li Peimo He Haijie Qian Fengqin Liu Yibulaxi Kuirexi 《中国科学A辑(英文版)》2000,43(11):1189-1194
K3C60, single crystal film was prepared on the cleaved (111) surface of C60, single crystal. Synchrotron radiation angle-resolved photoemission spectra were measured at normal emission with sample
temperature at × 150K. Up to four subpeaks of LUMO-derived band were observed. These sub-peaks exhibit distinct energy dispersions
which resemble in general the theoretical ones calculated for K3C60 at low temperature with the so-called one-dimensional disordered structure. But there is large deviation of experimental
sub-band intervals from the theoretical values. This result is meaningful for the studies of the physical properties of alkali-doped
C60 solids, e.g. the mechanism for superconductivity. 相似文献
95.
96.
Jumpei Saito Manabu Tanaka Kenji Miyatake Masahiro Watanabe 《Journal of polymer science. Part A, Polymer chemistry》2010,48(13):2846-2854
A new series of sulfonated polyimide (SPI) copolymers containing NH, OH, or COOH groups were synthesized by the polycondensation of 1,4,5,8‐naphthalnetetracarboxylic dianhydride, 3,3′‐bis(sulfopropoxy)‐4,4′‐diaminobiphenyl, and 3‐(4‐aminophenyl)‐5‐(3‐aminophenyl)‐1H‐1,2,4‐triazole (SPI‐8‐m), 3,5‐bis(4‐aminophenyl)‐1H‐1,2,4‐triazole (SPI‐8‐p), 3,6‐diaminocarbazole (SPI‐9), 3,5‐diamino‐1H‐1,2,4‐triazole (SPI‐10), bis(3‐aminopropyl)‐amine (SPI‐11), 2,6‐diaminopurine (SPI‐12), 2,4‐diamino‐6‐hydroxyprymidine (SPI‐13), or 3,5‐bis(4‐aminophenoxy)benzoic acid (SPI‐14). The obtained SPIs were soluble in polar organic solvents and gave tough and flexible membranes by solution casting. The SPI membranes having NH and COOH groups showed high thermal (decomposition temperature ≈200 °C) and mechanical (maximum stress >22 MPa) stability. Introducing NH groups, especially triazole and carbazole groups, was effective in improving proton conductive properties of SPI membranes at low humidity. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2846–2854, 2010 相似文献
97.
Thermography is a promising method for detecting subsurface defects, but accurate measurement of defect depth is still a big challenge because thermographic signals are typically corrupted by imaging noise and affected by 3D heat conduction. Existing methods based on numerical models are susceptible to signal noise and methods based on analytical models require rigorous assumptions that usually cannot be satisfied in practical applications. This paper presents a new method to improve the measurement accuracy of subsurface defect depth through determining the thermal wave reflection coefficient directly from observed data that is usually assumed to be pre-known. This target is achieved through introducing a new heat transfer model that includes multiple physical parameters to better describe the observed thermal behaviour in pulsed thermographic inspection. Numerical simulations are used to evaluate the performance of the proposed method against four selected state-of-the-art methods. Results show that the accuracy of depth measurement has been improved up to 10% when noise level is high and thermal wave reflection coefficients is low. The feasibility of the proposed method in real data is also validated through a case study on characterising flat-bottom holes in carbon fibre reinforced polymer (CFRP) laminates which has a wide application in various sectors of industry. 相似文献
98.
S.H. Momeni‐Masuleh A. Malek 《Numerical Methods for Partial Differential Equations》2007,23(5):1139-1148
This research aims to develop a time‐dependent pseudospectral‐finite difference scheme for solving a 3D dual‐phase‐lagging heat transport equation in a submicroscale thin film. The scheme uses periodic pseudospectral discretization in space and a fully second‐order finite difference discretization in time. The three consecutive time steps model is then solved explicitly, by using a preconditioned conjugate gradient method. The scheme is illustrated by an example which is used to investigate the heat transfer in a gold submicroscale thin film. Comparisons are made with available literature. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
99.
Mo Jiaqi Chen Xianfeng Xie Feng 《Annals of Differential Equations》2007,23(1):45-49
In this paper, the heat conductive problem with boundary perturbations is considered. Using the solvability of the problem, two eigenfunctions corresponding to two eigenvalues for the nm-th modular form are obtained. 相似文献
100.
K. -M. Haendel U. Denker O. G. Schmidt A. G. M. Jansen R. J. Haug 《Physica E: Low-dimensional Systems and Nanostructures》2004,21(2-4):487
We use magneto-transport spectroscopy to study a dramatic instability between a low and high conductivity mode in Si/SiGe-based resonant tunneling diodes with an embedded layer of self-assembled Ge hut cluster quantum dots in the Si barrier. In the low current regime a simple activation-type behavior with an astonishingly low activation energy in the order of 0.1 meV is determined. In the high current regime a region of negative differential conduction can be observed. We discuss the influence of different layer structures and magnetic fields. 相似文献