摘要：
We report on the high thermoelectric performance of p-type polycrystalline BiCuSeO, a layered oxyselenide composed of alternating conductive (Cu2Se2)(2-) and insulating (Bi2O2)(2+) layers. The electrical transport properties of BiCuSeO materials can be significantly improved by substituting Bi3+ with Ca2+. The resulting materials exhibit a large positive Seebeck coefficient of similar to+330 mu VK-1 at 300 K, which may be due to the 'natural superlattice' layered structure and the moderate effective mass suggested by both electronic density of states and carrier concentration calculations. After doping with Ca, enhanced electrical conductivity coupled with a moderate Seebeck coefficient leads to a power factor of similar to 4.74 mu Wcm(-1)K(-2) at 923K. Moreover, BiCuSeO shows very low thermal conductivity in the temperature range of 300 (similar to 0.9 Wm(-1)K(-1)) to 923K (similar to 0.45 Wm(-1)K(-1)). Such low thermal conductivity values are most likely a result of the weak chemical bonds (Young's modulus, E similar to 76.5GPa) and the strong anharmonicity of the bonding arrangement (Gruneisen parameter, gamma similar to 1.5). In addition to increasing the power factor, Ca doping reduces the thermal conductivity of the lattice, as confirmed by both experimental results and Callaway model calculations. The combination of optimized power factor and intrinsically low thermal conductivity results in a high ZT of similar to 0.9 at 923K for Bi0.925Ca0.075CuSeO.
通讯机构：
[Zinin, Pavel V.] Univ Hawaii, Hawaii Inst Geophys & Planetol, Honolulu, HI 96822 USA.
摘要：
Here, we report measurements of the Raman spectra of graphitic g-C3N4 phase, using deep ultraviolet (UV, 244 nm) and near-infrared (NIR, 785 nm) light for excitation of Raman scattering. It is demonstrated that the UV and NIR Raman spectra of g-C3N4 phases are substantially different from those measured with visible Raman spectroscopy. A typical Raman spectrum of the g-C3N4 phase obtained with visible Raman spectroscopy shows two main overlapping bands at 1357 and 1560 cm (1). In contrast, UV and NIR Raman spectra of g-C3N4 phase exhibit two strong peaks around 691 and 988 cm (1). These peaks are tentatively assigned to different types of the s-triazine ring breathing modes. Strong and distinguished features of the UV and NIR Raman spectra of g-C3N4 phases should provide a valuable 'finger-print' for Raman spectroscopy studies of phase transition of these phases under high pressure and high temperatures. (C) 2009 Elsevier B. V. All rights reserved.
通讯机构：
[Wu, Xiaomeng] Univ Georgia, Dept Food Sci & Technol, Nanoscale Sci & Engn Ctr, Athens, GA 30602 USA.
摘要：
High-quality surface-enhanced Raman scattering (SERS) spectra of aflatoxin (AF) B(1), B(2), G(1) and G(2) have been acquired using silver nanorod (AgNR) array substrates fabricated by oblique angle deposition method. Significant vibrational peaks are identified on the argon plasma-cleaned substrates, and those peaks agree very well with the Raman spectra calculated by density function theory (DFT). The concentration-dependent SERS detection is also explored. The relationship between the concentration (C) of different AFs and the SERS intensity (I) of the Raman peak at Deltanu = 1592 cm(-1) is found to follow the general relationship I = AC(alpha), with alpha ranging from 0.32 to 0.46 for the four AFs. The limits of detection (LODs) reach 5 x 10(-5) mol L(-1) for AFB(1), 1 x 10(-4) mol L(-1) for AFB(2), and 5 x 10(-6) mol L(-1) for both AFG(1) and AFG(2) in bulk solution, or 6.17 x 10(-16) mol/1.93 x 10(-4) ng of AFB(1), 1.23 x 10(-15) mol/3.88 x 10(-4) ng for AFB(2), 6.17 x 10(-17) mol/2.03 x 10(-5) ng for AFG(1), and 6.17 x 10(-17) mol/2.04 x 10(-5) ng for AFG(2) per laser spot. Principal component analysis (PCA) is used to successfully differentiate these four different kinds of AFs at different concentrations up to their detection limits. The LODs obtained from PCA agree with the LODs obtained by using peak fitting method. With such a low detection limit and outstanding differentiation ability, we prove the possibility of utilizing the SERS detection system as a platform for highly sensitive mycotoxin detection.
摘要：
In this work, ultrahigh molecular weight polyethylene (UHMWPE) was modified with oxygen plasma generated by microwave electron cyclotron resonance (ECR). Surface microstructure and properties of UHMWPE were studied by means of water contact angle measurement, Fourier transform infrared spectroscopy (FTIR). X-ray photoelectron spectroscopy, scratch test and wear test. The results showed that O-2 plasma treatment could effectively improve the wettability, anti-scratch and tribological properties of UHMWPE. Many oxygen-based functional groups generated on the surface of the O-2 plasma modified UHMWPE, which resulted in the improvement of wettability. The plasma treatment process increased the crosslinking of UHMWPE molecular chains, which further enhanced the action force between the molecular chains and finally increased the surface hardness, anti-scratch capacity and tribological properties of UHMWPE. (C) 2010 Published by Elsevier B.V.
作者机构：
[Wei, L. F.; Jia, W. Z.] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Quantum Optoelect Lab, Chengdu 610031, Peoples R China.;[Wei, L. F.] Sun Yet Sen Univ, Sch Phys Sci & Engn, State Key Lab Optoelect Mat & Technol, Guangzhou 510275, Guangdong, Peoples R China.;[Li, Yong] Beijing Computat Sci Res Ctr, Beijing 100084, Peoples R China.;[Li, Yong] Univ Sci & Technol China, Synerget Innovat Ctr Quantum Informat & Quantum P, Hefei 230026, Anhui, Peoples R China.;[Liu, Yu-Xi] Tsinghua Univ, Inst Microelect, Beijing 100084, Peoples R China.
通讯机构：
[Jia, W. Z.] Southwest Jiaotong Univ, Sch Phys Sci & Technol, Quantum Optoelect Lab, Chengdu 610031, Peoples R China.
摘要：
We explore theoretically the optical response properties in an optomechanical system under an electromagnetically induced transparency condition but with the mechanical resonator being driven by an additional coherent field. In this configuration, more complex quantum coherent and interference phenomena occur. In particular, we find that the probe transmission spectra depend on the total phase of the applied fields. Our study also provides an efficient way to control propagation of a probe field from perfect absorption to remarkable amplification.
摘要：
Recent works [Shen et al., Phys. Rev. Lett. 95, 213001 (2005); Zhou et al., Phys. Rev. Lett. 101, 100501 (2008)] showed that the incident photons cannot transmit along an optical waveguide containing a resonant two-level atom (TLA). Here we propose an approach to overcome such a difficulty by using asymmetric couplings between the photons and a TLA. Our numerical results show that the transmission spectrum of the photon depends on both the frequency of the incident photons and the photon-TLA couplings. Consequently, this system can serve as a controllable photon attenuator, by which the transmission probability of the resonantly incident photons can be changed from 0% to 100 % . A possible application to explain the recent experimental observations [Astafiev et al., Science 327, 840 (2010)] is also discussed.
作者：
Hubmayr, J.*;Beall, J.;Becker, D.;Cho, H-M;Devlin, M.;Dober, B.;Groppi, C.;Hilton, G. C.;Irwin, K. D.;Li, D.;Mauskopf, P.;Pappas, D. P.;Van Lanen, J.;Vissers, M. R.;Wang, Y.;Wei, L. F.;Gao, J.
作者机构：
[Becker, D.; Van Lanen, J.; Cho, H-M; Vissers, M. R.; Li, D.; Hilton, G. C.; Pappas, D. P.; Wang, Y.; Gao, J.; Hubmayr, J.; Beall, J.] NIST, 325 Broadway, Boulder, CO 80305 USA.;[Dober, B.; Devlin, M.] Univ Penn, Dept Phys & Astron, Philadelphia, PA 19104 USA.;[Groppi, C.; Mauskopf, P.] Arizona State Univ, Sch Earth & Space Explorat, Tempe, AZ 85281 USA.;[Irwin, K. D.] Stanford Univ, Dept Phys, Stanford, CA 94305 USA.;[Wei, L. F.; Wang, Y.] Southwest Jiaotong Univ, Quantum Optoelect Lab, Chengdu, Peoples R China.
通讯机构：
[Hubmayr, J.] NIST, 325 Broadway, Boulder, CO 80305 USA.
摘要：
We demonstrate photon-noise limited performance at sub-millimeter wavelengths in feedhorn-coupled, microwave kinetic inductance detectors made of a TiN/Ti/TiN trilayer superconducting film, tuned to have a transition temperature of 1.4 K. Micro-machining of the silicon-on-insulator wafer backside creates a quarter-wavelength backshort optimized for efficient coupling at 250 mu m. Using frequency read out and when viewing a variable temperature blackbody source, we measure device noise consistent with photon noise when the incident optical power is >0.5 pW, corresponding to noise equivalent powers > 3 x 10(-17)W/root Hz. This sensitivity makes these devices suitable for broadband photometric applications at these wavelengths. (C) 2015 AIP Publishing LLC.
摘要：
A stable and efficient anti-collision protocol is very important for tags identification in many radio frequency identification (RFID) system such as flow productions and automatic controls. In this paper, we introduce an efficient anti-collision protocol named collision tree protocol (CT) and analyze the stability of it in detail. Both theoretical results and experimental results indicate that the performance of CT is only dependent on the number of tags to be identified and not influenced by the distribution of tag IDs and other factors, and the average performance of CT for one-tag identification converges to a constant. According to the definition of the stability of an anti-collision protocol, CT is a stable anti-collision protocol for RFID tag identification. The stability proposed in this paper provides a new performance metric for evaluating the performance of different anti-collision protocols for RFID tag identification. As a stable protocol, the time delay and the power consumption for one-tag identification of CT tend to be constant. Therefore, CT can be applied to various tags identification systems and especially suited to the RFID systems in which both the time delay and the power consumption for tags (or objects) identification are required to be limited and stable.
期刊：
PROGRESS IN ELECTROMAGNETICS RESEARCH-PIER,2010年108:141-153 ISSN：1559-8985
通讯作者：
Wu, Y. -L
作者机构：
[Liao, C.; Wu, Y. -L; Xiong, X. -Z] SW Jiaotong Univ, Inst Electromagnet, Chengdu 610031, Peoples R China.
通讯机构：
[Wu, Y. -L] SW Jiaotong Univ, Inst Electromagnet, Chengdu 610031, Peoples R China.
摘要：
A novel dual-wideband microstrip bandpass filter (BPF) with improved upper-stopband performance is presented. With the use of some special structures such as E-shaped microstrip Stepped-Impedance Resonator (SIR) and input-output cross-coupling feed structure, this filter can generate five transmission zeros which are beneficial for improving its frequency selectivity and upper-stopband performance. finally the microstrip dual-wideband BPF has been simulated, fabricated and measured. Measurement results show that the two passbands are centered at 3.7 GHZ and 5.8 GHZ with the fractional bandwith of 31% and 13% respectively. Meanwhile more than 50% relative upper-stopband bandwith the 20 dB rejection has been realized. The simulated and measured results are in good agreement.
关键词：
Eddy current thermography;Lateral heat conduction;Rail oblique crack;Parallel crack
摘要：
Rail tread oblique crack, initiated by rolling contact fatigue (RCF) damage, is one of the most significant phenomena and has serious influence on rail industry. Electromagnetic non-destructive testing (EM NDT) methods are usually used in rail regular inspection. However, the conventional EM NDT methods based on eddy current field distribution are difficult to detect the cracks parallel to the inductive coil (parallel cracks) and natural oblique cracks. This paper studied lateral heat conduction (LHC) induced by eddy current for detection of these defects. The proposed method was verified through both numerical and experimental studies as well as the investigation of characteristic of LHC. Due to significant temperature gradient in the direction of lateral heat conduction, the spatial derivative and gradient were proposed to improve the defect detectability on the thermo-grams. Finally, the test of natural oblique cracks on a rail was conducted to validate the proposed methods. (C) 2015 Elsevier Ltd. All rights reserved.
通讯机构：
[Hou, B. P.] Sichuan Normal Univ, Inst Solid Phys, Coll Phys & Elect Engn, Chengdu 610101, Peoples R China.
摘要：
We present the normal-mode splitting and optomechanically induced transparency or absorption phenomena in the strongly tunnel-coupled optomechanical cavities. In the probe output spectrum, there appear central transparency windows or absorption peaks around which two broad sidebands are symmetrically located. It has been confirmed by the quantitative findings that two broad sidebands, which include the distorted absorption peaks, indicate the normal-mode splitting of the two hybridized cavities, and central transparency windows or absorption peaks character the interference induced by the optomechanical interactions. Additionally, the switching from absorption to amplification can be realized by only adjusting the tunnel interaction. These spectrum properties can be used for the coherent control of light pulses via microfabricated optomechanical arrays.
摘要：
The filter function of the metal–insulator–metal (MIM) waveguide with a gear-shaped nanocavity is investigated using the finite-difference time-domain method. Since the gear breaks the symmetric distribution of the resonance, Fano resonance occurs in the gear-shaped nanocavity. Fano resonance strongly depends on the structural parameters of the gear. Compared to the MIM waveguide with a disk-shaped nanocavity, the MIM waveguide with a gear-shaped nanocavity allows for a much more sensitive detection of small refractive index changes of the filled media inside the nanocavity, which reveals a potential sensor application of the MIM waveguide with a gear-shaped nanocavity.
作者：
Amenomori, M.*;Bi, X. J.;Chen, D.;Cui, S. W.;Danzengluobu;Ding, L. K.;Ding, X. H.;Fan, C.;Feng, C. F.;Feng, Zhaoyang;Feng, Z. Y.;Gao, X. Y.;Geng, Q. X.;Guo, H. W.;He, H. H.;He, M.;Hibino, K.;Hotta, N.;Hu, Haibing;Hu, H. B.
作者机构：
[Amenomori, M.; Nanjo, H.] Hirosaki Univ, Dept Phys, Hirosaki, Aomori 0368561, Japan.;[Wu, H. R.; Hu, H. B.; Zhang, Y.; Zhang, J. L.; Lu, S. L.; Tan, Y. H.; Lu, H.; Wang, Y.; Ding, L. K.; Wang, H.; Zhang, Yi; Zhang, H. M.; Ren, J. R.; Feng, Zhaoyang; He, H. H.; Bi, X. J.; Wang, B.; Huang, J.] Chinese Acad Sci, Inst High Energy Phys, Key Lab Particle Astrophys, Beijing 100049, Peoples R China.;[Takita, M.; Chen, D.; Ohnishi, M.; Sako, T. K.; Kawata, K.; Huang, J.; Yan, C. T.] Univ Tokyo, Inst Cosm Ray Res, Kashiwa, Chiba 2778582, Japan.;[Cui, S. W.] Hebei Normal Univ, Dept Phys, Shijiazhuang 050016, Peoples R China.;[Yuan, A. F.; Labaciren; Hu, Haibing; Zhaxisangzhu; Danzengluobu; Ding, X. H.; Guo, H. W.; Meng, X. R.] Tibet Univ, Dept Math & Phys, Lhasa 850000, Peoples R China.
摘要：
The Tibet-III air shower array, consisting of 533 scintillation detectors, has been operating successfully at Yangbajing in Tibet, China since 1999. Using the data set collected by this array from 1999 November through 2005 November, we obtained the energy spectrum of gamma-rays from the Crab Nebula, expressed by a power law as (dJ/dE) = (2.09 +/- 0.32) x 10(-12)(E/3 TeV)(-2.96 +/- 0.14) cm(-2) s(-1) TeV(-1) in the energy range of 1.7-40 TeV. This result is consistent with other independent gamma-ray observations by imaging air Cherenkov telescopes. In this paper, we carefully checked and tuned the performance of the Tibet-III array using data on the Moon's shadow in comparison with a detailed Monte Carlo (MC) simulation. The shadow is shifted to the west of the Moon's apparent position as an effect of the geomagnetic field, although the extent of this displacement depends on the primary energy of positively charged cosmic rays. This finding enables us to estimate the systematic error in determining the primary energy from its shower size. This error is estimated to be less than +/- 12% in our experiment. This energy scale estimation is the first attempt among cosmic ray experiments at ground level. The systematic pointing error is also estimated to be smaller than 0 degrees.011. The deficit rate and the position of the Moon's shadow are shown to be very stable within a statistical error of +/- 6% year by year. This guarantees the long-term stability of pointlike source observation with the Tibet-III array. These systematic errors are adequately taken into account in our study of the Crab Nebula.
关键词：
air;argon;finite difference time-domain analysis;high-frequency discharges;Monte Carlo methods;plasma collision processes;plasma simulation;plasma transport processes
摘要：
A modified electron energy distribution function (EEDF) is introduced into the fluid model and its effects on the high power microwave (HPM) breakdown in air and argon are investigated. A proper numerical scheme for the finite-difference time-domain method is employed to solve the fluid model. Numerical simulations show that the HPM breakdown time in argon predicted by the fluid model with the modified EEDF agrees well with the results of Particle-in-cell-Monte Carlo collision simulations, while the Maxwellian EEDF results in faster HPM breakdown when the mean electron energy is less than 20 eV. We also confirm that the Maxwellian EEDF can be used in the fluid model for simulating the air breakdown at the low frequencies based on the reported experiments. (C) 2011 American Institute of Physics. [doi:10.1063/1.3652845]
关键词：
Eddy current pulsed thermography;Rolling contact fatigue;Helmholtz coils;Nondestructive evaluation
摘要：
This paper reports on the use of eddy current pulsed thermography (ECPT) for detection and characterization of rolling contact fatigue (RCF). Detection mechanisms with eddy currents and heat propagation effects were discussed with RCF modeled as a simple angled defect. Two different angled defects were studied through numerical simulations and experimentally by using uniform magnetic field (UMF) excited by Helmholtz coils. Finally, a rail sample with RCF defects was inspected using UMF excitation. It is shown that ECPT with UMF excitation provides an efficient and robust method to detect angled defects, compared with nonuniform magnetic field (NUMF) excitation. (C) 2015 Elsevier Ltd. All rights reserved.
期刊：
JOURNAL OF OPTICS A-PURE AND APPLIED OPTICS,2009年11(10) ISSN：1464-4258
通讯作者：
Ji, Xiaoling
作者机构：
[Zhang, Tingrong; Jia, Xinhong; Ji, Xiaoling] Sichuan Normal Univ, Dept Phys, Chengdu 610068, Peoples R China.;[Zhang, Tingrong] SW Jiaotong Univ, Dept Phys, Coll Sci, Chengdu 610031, Peoples R China.
通讯机构：
[Ji, Xiaoling] Sichuan Normal Univ, Dept Phys, Chengdu 610068, Peoples R China.
关键词：
beam propagation factor (M-2-factor);partially coherent Hermite-Gaussian (H-G) array beam;superposition of the cross-spectral density function and of the intensity
摘要：
The analytical expression for the beam propagation factor (M-2-factor) of partially coherent Hermite-Gaussian (H-G) array beams is derived. It is shown that for the superposition of the intensity the M-2-factor increases monotonically with increasing the beam order, the beam number and the relative beam separation distance, and decreasing the beam coherence parameter. However, for the superposition of the cross-spectral density function there may appear a minimum of the M-2-factor as the beam number or the beam coherence parameter changes. On the other hand, a comparison of the M-2-factor between the two types of superposition is also given. It is found that the M-2-factor for the superposition of the cross-spectral density function may be smaller or larger than that for the superposition of the intensity depending on the beam order and the relative beam separation distance. However, the M-2-factor for the superposition of the cross-spectral density function is always smaller than that for the superposition of the intensity when the beam order is equal to zero or the relative beam separation distance is small enough. In particular, the M-2-factor is nearly the same for the two types of superposition when the beam coherence parameter is small enough or the relative beam separation distance is large enough.
关键词：
cosmic rays;diffusion;ISM: magnetic fields;solar neighborhood;Sun: activity
摘要：
We analyze the large-scale two-dimensional sidereal anisotropy of multi-TeV cosmic rays (CRs) by the Tibet Air Shower Array, with the data taken from 1999 November to 2008 December. To explore temporal variations of the anisotropy, the data set is divided into nine intervals, each with a time span of about one year. The sidereal anisotropy of magnitude, about 0.1%, appears fairly stable from year to year over the entire observation period of nine years. This indicates that the anisotropy of TeV Galactic CRs remains insensitive to solar activities since the observation period covers more than half of the 23rd solar cycle.
摘要：
In this work, pectin, a by-product has not been recycled sustainably, is introduced as an insulator to fabricate a novel organic resistive switching memory devices with Ag/Pectin/FTO structure for the first time. The device exhibits superior switching endurance accompanied by an OFF/ON resistance ratio (storage density window) of similar to 450. This work reveals for the first time that pectin from fruit peel is a promising material for nonvolatile memory applications. (C) 2016 Elsevier B.V. All rights reserved.
摘要：
The paper presents the investigation of the effect of the process parameters on the structure of hydrogenated amorphous carbon (a-C:H) films deposited on Si(100) substrate by electron cyclotron resonance microwave plasma chemical vapor deposition method (ECR-PCVD). The investigation is based on an orthogonal experimental design and analysis method. Both the carbon sp(3)/sp(2) bonding ratio and hydrogen content are evaluated from the visible Raman spectra deconvolution. The statistical results indicate that the sp(3)/sp(2) bonding ratio is mainly affected by microwave power, and it decreases as the microwave power increases. The hydrogen content in a-C:H films is mainly affected by the substrate bias voltage, and it decreases with increasing the bias voltage. The effect of other parameters on the structure of a-C:H films is relatively not significant, but is also discussed in the paper. (C) 2010 Elsevier B.V. All rights reserved.