2017
2017
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Record 1 of
Title:Ultrafast all-optical imaging technique using low-temperature grown GaAs/AlxGa1 ? xAs multiple-quantum-well semiconductor
Author(s):Gao, Guilong(1,2,3); Tian, Jinshou(1,4); Wang, Tao(1); He, Kai(1); Zhang, Chunmin(2); Zhang, Jun(5); Chen, Shaorong(5); Jia, Hui(5); Yuan, Fenfang(5); Liang, Lingliang(5); Yan, Xin(1); Li, Shaohui(1); Wang, Chao(1); Yin, Fei(1)Source: Physics Letters, Section A: General, Atomic and Solid State Physics Volume: 381 Issue: 41 DOI: 10.1016/j.physleta.2017.08.064 Published: November 5, 2017Abstract:We report and experimentally demonstrate an ultrafast all-optical imaging technique capable of single-shot ultrafast recording with a picosecond-scale temporal resolution and a micron-order two-dimensional spatial resolution. A GaAs/AlxGa1 ? xAs multiple-quantum-well (MQW) semiconductor with a picosecond response time, grown using molecular beam epitaxy (MBE) at a low temperature (LT), is used for the first time in ultrafast imaging technology. The semiconductor transforms the signal beam information to the probe beam, the birefringent delay crystal time-serializes the input probe beam, and the beam displacer maps different polarization probe beams onto different detector locations, resulting in two frames with an approximately 9 ps temporal separation and approximately 25 lp/mm spatial resolution in the visible range. ? 2017 Elsevier B.V.Accession Number: 20202208736873 -
Record 2 of
Title:An Efficient Contrast Enhancement Method for Remote Sensing Images
Author(s):Liu, Jiahang(1,2); Zhou, Chenghu(2); Chen, Peng(3); Kang, Chaomeng(1)Source: IEEE Geoscience and Remote Sensing Letters Volume: 14 Issue: 10 DOI: 10.1109/LGRS.2017.2730247 Published: October 2017Abstract:Remote sensing images often suffer low contrast. Although many contrast enhancement methods have been proposed in recent literature, the efficiency and robustness of remote sensing image contrast enhancement is still a challenge. In this letter, a novel self-adaptive histogram compacting transform-based contrast enhancement method for remote sensing images is presented to meet with the requirements of automation, robustness, and efficiency in applications. First, the histogram of an input image is optimized into compact and continuous status with the constraints of the merging cost, the moderate global brightness, and the entropy contribution of gray levels. Then, a local remapping algorithm is proposed to catch more details during the course of gray extending with the linear stretch. Finally, a dual-gamma transform is proposed to enhance the contrast in both bright and black areas. Experimental and comparison results demonstrate that the proposed method yields better results than the state-of-the-art methods and maintains robustness in different cases. It provides an effective approach for remote sensing image automatic contrast enhancement. ? 2017 IEEE.Accession Number: 20173504105805 -
Record 3 of
Title:Electron optics design of an 8-in. spherical MCP-PMT
Author(s):Chen, Ping(1,2,4); Tian, Jinshou(1,4); Qian, Sen(3); Zhao, Tianchi(3); Liu, Hulin(1); Wei, Yonglin(1); Sai, Xiaofeng(1); He, Jianping(1); Wang, Xing(1); Lu, Yu(1); Chen, Lin(1,2); Guo, Lehui(1,2); Pei, Chengquan(1,2); Hui, Dandan(1,2)Source: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment Volume: 848 Issue: DOI: 10.1016/j.nima.2016.11.054 Published: March 11, 2017Abstract:This paper discusses the electron optical system of an 8-in. spherical MCP-PMT. The MCP assembly, the supporting pole and the supply voltages are carefully designed to optimize the photoelectron collection efficiency and the transit time spread. Coating the MCP nickel-chromium electrode with an additional high secondary emission material is employed to make a breakthrough on the collection efficiency. With the simulation software CST, the Finite Integration method and the Monte Carlo method are combined to evaluate the collection efficiency, the time properties and the Earth's magnetic field effects. Simulation results show that the photocathode active solid angle is over 3.5 πsr, the average collection efficiency can exceed 95% with the coated MCP and the mean transit time spread is 2.2?ns for a typical electric potential of 500?V applied between the photocathode and the MCP input facet. The prototype and the measured single photoelectron spectrum are also presented. ? 2016 Elsevier B.V.Accession Number: 20170103208641 -
Record 4 of
Title:Research of nested X-ray concentrator for future X-ray timing astronomy
Author(s):Sheng, Lizhi(1,2); Zhao, Baosheng(1); Qiang, Pengfei(1); Liu, Duo(1)Source: Proceedings of SPIE - The International Society for Optical Engineering Volume: 10328 Issue: DOI: 10.1117/12.2268991 Published: 2017Abstract:X-ray grazing incidence optics are widely used in X-ray astronomy, especially for imaging payloads Wolter optics are the most workhorse. However, as there are two cascaded mirrors in Wolter type, the efficiency is quite low after two reflections. In this paper a kind of nested conical concentrator is developed with only one reflection to concentrate the X-ray photons and obtain the timing information. The mirror length is 200mm, the mirror foils cover from 38.8 to 100mm in diameter. D263T glass of 0.3mm thickness is used as mirror substrate with Iridium film deposited in order to improve the X-ray reflection. The D263T glass is slumped at 580°C with precisely machined and polished mold. 3D printed resin serves as upper mold for glass cutting. The quality of mirror substrate is mainly determined by the surface of forming mandrel. As the surface roughness is quite important for X-ray reflection, after deposition it is tested with interferometer and AFM, and the roughness is 0.6nm. Mirror integration based on visible light is built, and the conical mirrors are assembled and adjusted by real time monitoring for the focal point of visible light. With the monochromic X-ray source, the concentrator efficiency is tested as 38%@1.49keV, 20%@4.51keV. The focal point is Φ8.2mm in Xray, with 80% of its energy encircled in a 4mm width. This kind of X-ray concentrator could be used in X-ray navigation, X-ray communication and other X-ray timing astronomy. ? 2017 SPIE.Accession Number: 20171403517380 -
Record 5 of
Title:Measurement Method and Device for Transient Thermal Impedance of High Power IGBT Module
Author(s):Lu, Guoquan(1,2); Li, Jie(1); Mei, Yunhui(1); Li, Xin(1); Wang, Lei(3)Source: Tianjin Daxue Xuebao (Ziran Kexue yu Gongcheng Jishu Ban)/Journal of Tianjin University Science and Technology Volume: 50 Issue: 7 DOI: 10.11784/tdxbz201606072 Published: July 15, 2017Abstract:To characterize the thermal performance of high power insulated gate bipolar transistor(IGBT)module, a transient thermal impedance measurement device based on the electrical method for IGBT module was designed and built. By changing heating pulse duration of the measurement device equal to the thermal time constants of different material layers, the effective thermal conduction paths in IGBT module can be controlled and the transient thermal impedance of each component within the IGBT module can be obtained. In addition, the impacts of the transient noise in the instant transformation of high-low level and the boundary heat condition on measurement accuracy were discussed. Results show that the device has good accuracy and repeatability, which will prove useful in analyzing the thermal dispersion performance of different devices and packaging materials under transient conditions accurately and nondestructively and guiding the IGBT module structure design and packaging material selection. ? 2017, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.Accession Number: 20174304293547 -
Record 6 of
Title:Online measurement of atmospheric density based on space vehicle platform
Author(s):Wang, Chao-Jie(1,2); Wang, Bo(3); Guo, Hui-Nan(4); Qin, Lai-An(5)Source: Guangxue Jingmi Gongcheng/Optics and Precision Engineering Volume: 25 Issue: 1 DOI: 10.3788/OPE.20172501.0015 Published: January 1, 2017Abstract:In view of the high-altitude atmospheric density fluctuation and the difficulty to identify aerodynamic characteristics of the aircraft in orbit, a technical solution for atmospheric density measurement by lidar based on Rayleigh scattering principle was proposed. The online data of atmospheric density at different distances was acquired through the analysis of the laser backscattering Rayleigh optical cylinder, which was captured by the Electron-Multiplying Charge Coupled Device (EMCCD) in the measuring flow field based on the principle that the density of gas molecules is in direct proportion to Rayleigh scattering intensity. Furthermore the atmospheric density online measuring instrument was developed and calibrated. Experimental and calibration results show that the online measurement precision of atmospheric density is controlled within 5%. The instrument has a promising application in optimization of spacecraft appearance and improvement of aerodynamic identification. ? 2017, Science Press. All right reserved.Accession Number: 20172203698736 -
Record 7 of
Title:Ultrafast all-optical solid-state framing camera with picosecond temporal resolution
Author(s):Gao, Guilong(1,2,3); He, Kai(1); Tian, Jinshou(1,4); Zhang, Chunmin(2); Zhang, Jun(5); Wang, Tao(1); Chen, Shaorong(5); Jia, Hui(5); Yuan, Fenfang(5); Liang, Lingliang(1,2,3); Yan, Xin(1); Li, Shaohui(1); Wang, Chao(1); Yin, Fei(1)Source: Optics Express Volume: 25 Issue: 8 DOI: 10.1364/OE.25.008721 Published: April 17, 2017Abstract:A new ultrafast all-optical solid-state framing camera (UASFC) capable of single-shot ultrafast imaging is proposed and experimentally demonstrated. It is composed of an ultrafast semiconductor chip (USC), an optical time-series system (TSS), and a spatial mapping device (SMD) with an USC to transform signal beam information to the probe beam, a TSS to convert the time axis to wavelength-polarization, and a SMD to map wavelength-polarization image to different spatial positions. In our recent proof-of-principle experiment, better performance than ever of this technique is confirmed by giving six frames with ～3 ps temporal resolution and ～30 lp/mm spatial resolution. ? 2017 Optical Society of America.Accession Number: 20171703605084 -
Record 8 of
Title:Transfer process of LT-GaAs epitaxial films for on-chip terahertz antenna integrated device
Author(s):Guo, Chun-Yan(1,2,3); Xu, Jian-Xing(3,4); Peng, Hong-Ling(5); Ni, Hai-Qiao(4); Wang, Tao(1); Tian, Jin-Shou(1); Niu, Zhi-Chuan(4); Wu, Zhao-Xin(2); Zuo, Jian(6); Zhang, Cun-Lin(6)Source: Hongwai Yu Haomibo Xuebao/Journal of Infrared and Millimeter Waves Volume: 36 Issue: 2 DOI: 10.11972/j.issn.1001-9014.2017.02.016 Published: April 1, 2017Abstract:A process for LT-GaAs used as photoconductive switch in epitaxial layer transfer of on-chip THz antenna integrated device was provided. Hall indicated resistivity of the epitaxial materials gained by MBE was about 106Ω·cm. HNO3-NH4OH-H2O-C3H8O7·H2O-H2O2-HCl and wet chemical etching were used to etch epitaxial materials grown by MBE. Gained the structure that 1.5μm LT-GaAs bounded with COP after lift-off of SI-GaAs and Al0.9Ga0.1As. AFM, SEM and high-power microscope indicated that the structure was flat and smooth after lift-off. RMS=2.28 nm. EDAX indicated there wasn't Al in this structure. It can be used to make photoconductive switch. ? 2017, Science Press. All right reserved.Accession Number: 20172103693124 -
Record 9 of
Title:Comparison of nanoparticle generation by two plasma techniques: Dielectric barrier discharge and spark discharge
Author(s):Jiang, Lun(1,2); Li, Qing(1); Zhu, Dandan(1); Attoui, Michel(3); Deng, Zhi(2); Tang, Jie(4); Jiang, Jingkun(1,5)Source: Aerosol Science and Technology Volume: 51 Issue: 2 DOI: 10.1080/02786826.2016.1260681 Published: February 1, 2017Abstract:Dielectric barrier discharge (DBD) and spark discharge, two versatile atmospheric pressure plasma-based techniques, have been employed to generate nanoparticles. This study compares the characteristics of metal nanoparticles generated by a DBD reactor and a spark discharge generator with argon as the working gas. The gas temperature in the discharge region of the DBD reactor remained near room temperature, while that of the spark reactor varied from 470 to 1120?K and generally increased with increasing applied voltage amplitude in the range of 2–10?kV and driving frequency in the range of 1–10?kHz. Comparing to spark-generated nanoparticles under the same voltage, frequency, and flow rate, DBD-generated nanoparticles have smaller sizes, better monodispersity, and lower number concentrations. The number concentration of DBD-generated particles decreases significantly under high working voltage and frequency, while the number concentration of spark-generated particles increases with increasing working voltage. Under continuous operations over several hours, the DBD reactor has better temporal stability in generating nanoparticles than the spark generator. ? 2017 American Association for Aerosol Research ? 2017 American Association for Aerosol Research.Accession Number: 20165003113716 -
Record 10 of
Title:Overlapping community detection for multimedia social networks
Author(s):Huang, Faliang(1); Li, Xuelong(2); Zhang, Shichao(3); Zhang, Jilian(4); Chen, Jinhui(5); Zhai, Zhinian(6)Source: IEEE Transactions on Multimedia Volume: 19 Issue: 8 DOI: 10.1109/TMM.2017.2692650 Published: August 2017Abstract:Finding overlapping communities from multimedia social networks is an interesting and important problem in data mining and recommender systems. However, extant overlapping community discovery with swarm intelligence often generates overlapping community structures with superfluous small communities. To deal with the problem, in this paper, an efficient algorithm (LEPSO) is proposed for overlapping communities discovery, which is based on line graph theory, ensemble learning, and particle swarm optimization (PSO). Specifically, a discrete PSO, consisting of an encoding scheme with ordered neighbors and a particle updating strategy with ensemble clustering, is devised for improving the optimization ability to search communities hidden in social networks. Then, a postprocessing strategy is presented for merging the finer-grained and suboptimal overlapping communities. Experiments on some real-world and synthetic datasets show that our approach is superior in terms of robustness, effectiveness, and automatically determination of the number of clusters, which can discover overlapping communities that have better quality than those computed by state-of-the-art algorithms for overlapping communities detection. ? 1999-2012 IEEE.Accession Number: 20173704163011 -
Record 11 of
Title:Optical spectroscopic characterizations of laser irradiated olivine grains
Author(s):Yang, Yazhou(1); Zhang, Hao(1,2); Wang, Ziwei(1); Yuan, Ye(1); Li, Shaolin(3); Hsu, Weibiao(3); Liu, Chujian(4)Source: Astronomy and Astrophysics Volume: 597 Issue: DOI: 10.1051/0004-6361/201629327 Published: January 1, 2017Abstract:Context. Visible and near-infrared spectra of asteroids are known to be susceptible to nanophase irons produced by space weathering processes, thus making mineral identifications difficult. Mid-infrared spectroscopy may retain more mineral features owing to its lattice vibrational nature. Aims. We investigate the structure and reflectance spectral feature changes of olivine grains before and after simulated space weathering. Methods. We irradiate olivine grains by using pulsed laser to simulate varying degrees of micrometeorite bombardments. Reflectance measurements from 0.5 to 25 μm and radiative transfer calculations were carried out in order to compare them with each other. Results. Both the experimental simulations and modeling results indicate that the mid-infrared spectral features of olivine grains can survive the intense irradiations. Although the Christansen Feature is slightly shifted to longer wavelength, major vibrational bands remain essentially unchanged, because the lattice structure is quite immune to even the strongest irradiations, as revealed by both the X-ray diffraction and Raman scattering measurements. Conclusions. Mid-infrared spectroscopy is much more immune to productions of nanophase irons and amorphous materials and thus may be used more reliably in remote detections of minerals on asteroid surfaces. ? ESO, 2016.Accession Number: 20165303205453 -
Record 12 of
Title:Novel frontiers in the stabilization of FD-FWM microcombs
Author(s):Bao, Hualong(1); Cooper, Andrew(1); Chu, Sai T.(2); Moss, David J.(3); Morandotti, Roberto(4); Little, Brent E.(5); Peccianti, Marco(1); Pasquazi, Alessia(1)Source: ICOCN 2017 - 16th International Conference on Optical Communications and Networks Volume: 2017-January Issue: DOI: 10.1109/ICOCN.2017.8121593 Published: November 27, 2017Abstract:In this contribution, we will review our recent activities in the development of double nested cavity lasers. Several stable operating regimes can be achieved over a wide range of conditions. ? 2017 IEEE.Accession Number: 20181104902971