2011
2011
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Record 373 of
Title:Fabrication of high thermal conductive Al-cBN ceramic sinters by high temperature high pressure method
Author(s):Wang, P.F.(1,2); Li, Zh.H.(2); Zhu, Y.M.(2)Source: Solid State Sciences Volume: 13 Issue: 5 DOI: 10.1016/j.solidstatesciences.2011.01.023 Published: May 2011Abstract:Al-cBN ceramic sinters were fabricated by sintering micro-powder mixture of Al and cBN under high temperature and high pressure condition. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), scanning electronic microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) elemental mapping analyses and laser flashing thermal conductivity measurements were performed to investigate the sintering properties and thermal conductivity of the Al-cBN ceramic sinters. XRD analysis revealed these Al-cBN ceramic sinters were composed of a large portion of cBN and of a small portion of AlN, and very little amount of AlB12 and hBN. Formation of boundary phase resulted in the rapid densification of the sinters, as well as the increase of their relative density with increasing Al additions. The Al-cBN ceramic sinters have a maximum thermal conductivity of about 1.94 W/cm K at room temperature and a much higher value of about 2.04 W/cm K at 200 °C. Their high thermal conductivity over that of AlN-hBN composites promise Al-cBN ceramic sinters favorite candidates as high efficiency heat sink materials for wide band gap semiconductors. ? 2011 Elsevier Masson SAS. All rights reserved.Accession Number: 20111813948956 -
Record 374 of
Title:Distributed temperature sensing system based on Rayleigh scattering BOTDA
Author(s):Cui, Qingsong(1,2); Pamukcu, Sibel(2); Lin, Aoxiang(3,4); Xiao, Wen(5); Herr, Douglas(6); Toulouse, Jean(7); Pervizpour, Mesut(8)Source: IEEE Sensors Journal Volume: 11 Issue: 2 DOI: 10.1109/JSEN.2010.2066558 Published: 2011Abstract:A distributed temperature sensor based on Rayleigh scattering Brillouin optical time domain analysis (Rayleigh-BOTDA) is proposed in this paper. The sensor uses Rayleigh backscattering effect of microwave modulated pulse base sidebands as probe wave and a high sensitive photon counting detector for Brillouin signal intensity detection. Compared with a conventional BOTDA system, the Rayleigh-BOTDA effectively suppresses polarization-induced signal fluctuation resulting in improved signal intensity. The experimental scheme presented is simplified by using a single laser with one-end access. The temperature accuracy of the new sensing system was demonstrated as 1 °C on spatial resolution of 3 m. ? 2010 IEEE.Accession Number: 20104813428530 -
Record 375 of
Title:Influences of the thickness, misalignment, and dispersion of the Savart polariscope on the optical path difference and spectral resolution in the polarization interference imaging spectrometer
Author(s):Zhang, Chunmin(1); Zhao, Jianke(1,2); Sun, Yao(1,3)Source: Applied Optics Volume: 50 Issue: 20 DOI: 10.1364/AO.50.003497 Published: July 10, 2011Abstract:After reviewing the spectrum-dividing principle of the Savart polariscope (SP) in the polarization interference imaging spectrometer (PIIS) that we developed, we analyze the influences of the thickness, misalignment, and dispersion of the SP on the optical path difference (OPD). The theoretical expression of the OPD for the misalignment of the SP optical axis is deduced, and the OPD is analyzed when the incident plane is parallel, at 45°, or orthogonal to the principal section of the left plate of the SP. The selective thickness of the single Savart plate is analyzed when it is placed at the ideal and misalignment positions. The influence of dispersion of the SP on the OPD is analyzed when the misalignment error is ±1'. The relationships between the OPD and wavelength are simulated and validated with experiments. This work can provide theoretical and practical guidance for the design, calibration, modulation, innovation, experiment, and engineering of the PIIS. ? 2011 Optical Society of America.Accession Number: 20112914149153 -
Record 376 of
Title:Integrated solution for high resolution CCD camera imaging circuits
Author(s):Bai, Zhe(1,2); Xu, Yanbing(3); Zhang, Boheng(1); Duan, Kailiang(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 8194 Issue: DOI: 10.1117/12.901001 Published: 2011Abstract:In this paper,compared with the traditional CCD camera imaging circuits, a kind of integrated solution for CCD imaging circuits is put forward.The principle of the traditional CCD camera imaging circuits is described briefly, and the foundational functions are introduced. CCD imaging circuits are the most important parts of the CCD camera, and they are mainly made up of CCD driver circuits and CCD signal processing circuits. The CCD signal processing circuits mainly consist of timing generator, preamplifier circuits, CDS circuits, low-pass filter circuits, PGA circuits, ADC circuits, storage circuits, output interface circuits, and so on. The popular solution is that all the circuits are made with separate components.Complex circuit configuration, difficult debugging, uptight power dissipation are evident. However, it goes without saying that the integrated solutions which combine ADC with FPGA device are high integration, simple configuration and better agility. Finally, the integrated solution for CCD imaging circuits is illustrated, and the problems of the circuits are analyzed and summarized in detail. ? 2011 SPIE.Accession Number: 20113714325934 -
Record 377 of
Title:Electrical pulse generation technology for laser pulse shaping
Author(s):Gou, Yongsheng(1,2); Liu, Baiyu(1); Zhang, Wei(1,2); Bai, Yonglin(1); Bai, Xiaohong(1); Yang, Wenzheng(1); Qin, Junjun(1); Wang, Bo(1)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 11 DOI: Published: November 2011Abstract:A new circuit to generate ultra-wide-band pulse for laser pulse shaping used in "Shen Guang III" device was presented in this paper. This circuit was based on the characteristics of the step recovery diode (SRD) that the quantity of the carriers in the middle layer was controllable, the SRD had little parasitical capacitor and it would cut off rapidly. The pulse generation circuit was designed by combining the SRD in series and parallel. The ultra-wide-band pulse was tested specifically and test results of the practical circuit were given and analyzed in physical level. They were tallied with the theoretical results. This pulse generation circuit could output a pulse with amplitude about 10 V and pulse width about 150 ps. The trigger jitter of the pulse was less than 3 ps, amplitude stability was better than 3%. Thus, this circuit can meet the requirement of the pulse shaping.Accession Number: 20120314688090 -
Record 378 of
Title:Eliminating influence of grating encoder's eccentricity and vibration to moiré fringes signal by four reading heads
Author(s):Zhu, Fan(1); Wu, Yiming(1); Liu, Changchun(2)Source: Guangxue Xuebao/Acta Optica Sinica Volume: 31 Issue: 4 DOI: 10.3788/AOS201131.0412008 Published: April 2011Abstract:Presently, grating encoder is an important way to accurately measure angle, however, the eccentric inaccuracy of assembling adjusting and the vibration of rotating shaft influence grating encoder's measuring accuracy and then confine the application range of grating encoder. A new method to eliminate the influence of eccentricity and vibration with four reading heads is proposed and the theoretical derivation and simulation results are given out. The conclusion hints that the method which gets moiré fringes signal by four reading heads well-distributed along the circumference of grating is more effective in improving the measuring accuracy than the one that uses double reading heads. Consequently, the new method decreases the requirements of assembling adjusting. The direction and magnitude also can be solved by four reading heads, so the influence of rotating shaft can be eliminated. All the results are useful to deeper research.Accession Number: 20112013990640 -
Record 379 of
Title:Optical design of visible/infrared integrative camera
Author(s):Yang, Lihua(1,2); Fan, Xuewu(1); Zou, Gangyi(1); Yu, Shunjing(3)Source: Hongwai yu Jiguang Gongcheng/Infrared and Laser Engineering Volume: 40 Issue: 10 DOI: Published: October 2011Abstract:The optical system design of the visible/infrared integrative camera was introduced. In the system, the primary mirror was used for two wave bands together whose aperture was 1 m. In the visible band of 450-900 nm, the coaxial three-mirror-anastigmat system was chosen with focal length of 12.0 m and field of view of 1.5° × 0.5°, and TDICCD was used. In the infrared band of 8-12μm, the prime focus system was chosen with focal length of 2.0 m and field of view of 2.0°, which was composed of the primary mirror and three Ge lenses, and uncooled infrared detector was used. The first lens of the prime focus system was set behind the secondary mirror, the retainer of which can circumrotate 180°. When the secondary mirror was switched into the system, the visible camera was working, and when the secondary mirror was switched out of the system, the infrared camera was working. The optical system combines the two wave bands cameras together, which reduces the quality and volume of the camera, and realize the double uses of one star in its orbit.Accession Number: 20114814570319 -
Record 380 of
Title:Non-absorption grating approach for X-ray phase contrast imaging
Author(s):Du, Yang(1,2); Liu, Xin(1); Lei, Yaohu(1); Guo, Jinchuan(1); Niu, Hanben(1)Source: Optics Express Volume: 19 Issue: 23 DOI: 10.1364/OE.19.022669 Published: November 7, 2011Abstract:we demonstrate a non-absorption grating approach for X-ray phase contrast imaging based-on grating interferometry. This technique overcomes the limitations imposed by absorption gratings, provides another choice for X-ray phase contrast imaging and potentially improves the image quality for higher X-ray photon energies. We constructed the key devices, established the system and obtained phase contrast images with a field of view larger than 5 centimeters, which is the limitation imposed by the size of our current CCD detector. This method has no need for absorption gratings, which represents a significant development for future promising applications in medicine and industry. ? 2011 Optical Society of America.Accession Number: 20114614511971 -
Record 381 of
Title:The classification of SSH tunneled traffic using maximum likelihood classifier
Author(s):Tan, Xiaobing(1,2); Su, Xiuqin(1,2); Qian, Qingming(1,2)Source: 2011 International Conference on Electronics, Communications and Control, ICECC 2011 - Proceedings Volume: Issue: DOI: 10.1109/ICECC.2011.6066732 Published: 2011Abstract:Secure SHell(SSH) [1] provides TCP/IP port forwarding for any Application-layer protocols. It is useful in protecting the privacy of users, but it can lead to the illegal use of some forbidden protocols. Because of the encryption, the Deep Payload Inspection (DPI) technique is ineffective in classifying the network traffic. This paper introduces how to employ the statistical pattern recognition method, Maximum Likelihood Classification [2, 3], to classify the SSH tunneled traffic, i.e. to decide which protocols is tunneled in the encrypted tunnels. It is very important to find out the boundary of a tunneled flow in processing the originate data. So we proposed a method for detecting the boundaries of SSH tunneled traffic. ? 2011 IEEE.Accession Number: 20114714545013 -
Record 382 of
Title:Frequency compression of SR for detecting rotor's incipient fault signal
Author(s):Wang, Guo-Fu(1,2); Zhang, Hai-Ru(1); Zhang, Fa-Quan(1); Ye, Jin-Cai(1)Source: Dianji yu Kongzhi Xuebao/Electric Machines and Control Volume: 15 Issue: 6 DOI: Published: June 2011Abstract:Stochastic resonance system is only for small parameter (small amplitude and low frequency) system. However, the frequency of the fault signal of the rotor is higher than the stochastic resonance system. According to the basic theory of stochastic resonance systems, the limit of frequency range of the measure signal of the stochastic resonance system was eliminated by introducing the time-frequency compression algorithm, and stochastic resonance system was extended to the whole band. Theoretical and experimental results show that: by continuous compression transformation, an appropriate input signal was obtained to stochastic resonance system. The unknown frequencies of the original signal can be obtained, according to the change of resonant peaks and transformation operations. The algorithm is 6 orders of magnitude faster than the traditional algorithm of frequency sweep, and it can detect the fault signal under the limit SNR (-50 dB).Accession Number: 20113114198865 -
Record 383 of
Title:Research on endmember extraction algorithm based on spectral classification
Author(s):Gao, Xiao-Hui(1,3); Xiangli, Bin(2); Wei, Ru-Yi(1,3); Lü, Qun-Bo(2); Wei, Jun-Xia(1,3)Source: Guang Pu Xue Yu Guang Pu Fen Xi/Spectroscopy and Spectral Analysis Volume: 31 Issue: 7 DOI: 10.3964/j.issn.1000-0593(2011)07-1995-04 Published: July 2011Abstract:Spectral unmixing is an important task for data processing of hyperspectral remote sensing, which is comprised of extracting the pure spectra (endmember) and calculating the abundance value of pure spectra. The most efficient endmember extracting algorithms (EEAs) is designed based on convexity geometry such as pure pixel index (PPI), N-finder algorithm (N-FINDR). Most EEAs choose pure spectra from all pixels of an image so that they have disadvantages like slow processing speed and poor precision. Partial algorithms need reducing the spectral dimension, which results in the difficulty in small target identification. This paper proposed an algorithm that classifies the hyperspetral image into some classes with homogeneous spectra and considers the mean spectra of a class as standard spectra for the class, then extracts pure spectrum from all standard spectra of classes. It reduces computation and the effect of system error, enhancing the speed and precision of endmember extraction. Using the least squares with constraints on spectral extraction and spectral unmixing, by controlling the band average value of the maximum spectral redundant allowance to control the number of endmembers, does not need to reduce the spectral dimension and predetermine the number of endmembers, so compared to N-finder algorithm, such algorithm is more rational.Accession Number: 20112814137360 -
Record 384 of
Title:Image quality assessment based on S-CIELAB model
Author(s):He, Lihuo(1); Gao, Xinbo(1); Lu, Wen(1); Li, Xuelong(2); Tao, Dacheng(3)Source: Signal, Image and Video Processing Volume: 5 Issue: 3 DOI: 10.1007/s11760-010-0200-x Published: September 2011Abstract:This paper proposes a new image quality assessment framework which is based on color perceptual model. By analyzing the shortages of the existing image quality assessment methods and combining the color perceptual model, the general framework of color image quality assessment based on the S-CIELAB color space is presented. The S-CIELAB color model, a spatial extension of CIELAB, has an excellent performance for mimicking the perceptual processing of human color vision. This paper incorporates excellent color perceptual characteristics model with the geometrical distortion measurement to assess the image quality. First, the reference and distorted images are transformed into S-CIELAB color perceptual space, and the transformed images are evaluated by existing metric in three color perceptual channels. The fidelity factors of three channels are weighted to obtain the image quality. Experimental results achieved on LIVE database II shows that the proposed methods are in good consistency with human subjective assessment results. ? 2011 Springer-Verlag London Limited.Accession Number: 20113414264436