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| 1 | Phase demodulation method based on a dual-identical-chirped-pulse and weak fiber Bragg gratings for quasi-distributed acoustic sensing显示文摘A phase demodulation method for quasi-distributed acoustic sensing(DAS)systems based on a dual-identicalchirped-pulse and weak fiber Bragg gratings(WFBGs)is proposed.Compared to the use of Rayleigh backscattering light in optical fibers,the implementation of WFBGs can contribute to obtaining an optical signal with a higher signal-to-noise ratio(SNR).The dual-identical-chirped-pulse is generated by a time-delay fiber,and the sinusoidal carrier is generated by the interference between the two chirped pulses reflected by adjacent WFBGs.The phase of the sinusoidal carrier represents the dynamic strain change posed on the sensing fiber.Discrete Fourier transform is used to directly retrieve the phase information.The performance of the phase demodulation from interference signals under different sinusoidal carrier frequencies and SNRs is numerically investigated.The piezoelectric transducer is employed to emulate the sound in the experiment to verify the effectiveness of our method.It is shown that the dynamic strain can be well reconstructed at the end of a 101.64 km fiber when the signal SNR is down to 3.234 d B.Our proposed method enables the application of the long-distance sensing in quasi-DAS systems. | Guanhua Liang Junfeng Jiang Kun Liu Shuang Wang Tianhua Xu Wenjie Chen Zhe Ma Zhenyang Ding Xuezhi Zhang Yongning Zhang Tiegen Liu | 2020 | Photonics Research2020，8，7： | 6 |
| 2 | Strain effects on valence bands of wurtzite ZnO显示文摘Based on the k.p theory of Luttinger-Kohn and Bir-Pikus,analytical E-k solutions for the valence band of strained wurtzite ZnO materials are obtained.Strain effects on valence band edges and hole effective masses in strained wurtzite ZnO materials are also discussed.In comparison with unstrained ZnO materials,apparent movement of valence band edges such as 'light hole band','heavy hole band' and 'crystal splitting band' at Γ point is found in strained wurtzite ZnO materials.Moreover,effective masses of 'light hole band','heavy hole band' and 'crystal splitting band' for strained wurtzite ZnO materials as the function of stress are given.The analytical results can provide a theoretical foundation for the understanding of physics of strained ZnO materials and its applications with the framework for an effective mass theory. | QIAO LiPing CHAI ChangChun JIN Zhao YANG YinTang MA ZhenYang | 2013 | Science China(Physics,Mechanics & Astronomy)2013，56，9： | 3 |
| 3 | Application of Phase-Locked PIV Technique to the Measurements of Flow Field in a Turbine Stage显示文摘For the purpose of improving turbine efficiency,a detailed investigation of flow field near rim seal region in the main annulus is absolutely essential.Purge flow egressed from the seal gap penetrates the hub boundary layer and travels along with the secondary flow in the main path.The propagation of the purge flow and its influence on the turbine performance are crucial and cannot be neglected in the aerodynamic and thermal design.In addition,the interaction of vane wake and blade potential field also has a significant impact on the turbine stage performance.In this study,flow field between inlet guide vanes(IGV)and rotor blades was experimentally investigated at specific positions with the help of a two-dimensional particle image velocimetry(2-D PIV).A phase-locking technique was also employed to capture the images of flow field at different rotor blade positions.Data acquired characterizes the impact of emergent purge flow on the flow structures within the main annulus.The impacts of vane wake and blade potential field on the flow fields were analyzed through characterizations provided by the time-averaged field results.Finally,flow fields at different main flow rates and under different seal gap widths were also presented and assessed. | ZHANG Zhenyang MA Hongwei | 2020 | Journal of Thermal Science2020，29，3： | 2 |
| 4 | Effects of a Kind of Surface Groove on Flow Loss in Both Rectangular and Circular Ducts at Different Reynolds Numbers显示文摘Pipes are widely used to transport gas,oil and water in industries.Drag reduction in pipes is an increasingly concerned problem to save energy.Some researches have indicated that the non-smooth surface with special structures can reduce flow loss.In this paper,an experimental investigation has been performed on the effects of a kind of surface groove on the drag in both rectangular and circular duct at different Reynolds numbers.In the experiment of the rectangular duct,total pressure at both inlet and outlet were measured.Static pressure on the wall was measured on the surface with smooth and grooved film respectively.In the circular duct,a boundary layer pressure probe was used to measure the total pressure distribution at both inlet and outlet.Four taps at inlet and outlet were used to measure static pressure.The loss coefficient is used to evaluate the effects of the surface groove on drag reduction.The experiment was conducted with the Reynolds number range from 1.28×10~4 to 2.57×10~4.The result shows a maximum drag loss reduction of approximately 2.4% in rectangular duct at Reynolds number of 2.4×10~4.A 10%reduction of pipe pressure loss by grooved surface is measured in circular duct at a Reynolds number of 3.0×10~5. | MA Rong MA Hongwei ZHANG Zhenyang ZHANG Jinghui | 2016 | Journal of Thermal Science2016，25，5： | 2 |
| 5 | A novel colorimetric determination of reduced glutathione in A549 cells based on Fe304 magnetic nanoparticles as peroxidase mimetics显示文摘 | MA Yanhua ZHANG Zhenyang REN Cuiling | 2012 | Analyst2012，137，2： | 1 |
| 6 | Hardening measures for bipolar transistors against microwave-induced damage显示文摘 | Chai Changchun Ma Zhenyang Ren Xingrong | 2013 | Chinese Physics B2013，22，68： | 1 |
| 7 | Analysis of temperature-dependent characteristics of a 4H-SiC metal-semiconductor-metal ultraviolet photodetector显示文摘We investigate the temperature dependence of current-voltage and spectral response characteristics of a 4H-SiC metal-semicon-ductor-metal (MSM) ultraviolet photodetector in the temperature range from room temperature to 800 K with two-dimensional (2D) numerical simulator ISE-DESSIS. It is found that the dark current and photocurrent increase with the increasing temperature. For the range of 500-800 K, the dark current increases by nearly a factor 3.5 every 150 K larger than that of photocurrent, leading to a negative effect on photodetector current ratio (PDCR). Nevertheless, the PDCR is still greater than 200 even at 800 K, which exhibits the excellent thermal stability. In addition, the responsivity has an unsymmetrical trend. As temperature rises, it is clear that a remarkable red-shift of 12 nm occurs and overall responsivity is enhanced for longer wavelength. While the short-wave-length response remains relatively independent of temperature. The mechanism of indirect and direct band absorption transition is responsible for temperature-dependent spectrum distribution. These findings provide a significant insight on the design of the MSM detector operated at elevated temperature. | CHEN Bin YANG YinTang XIE XuanRong WANG Ning MA ZhenYang SONG Kun ZHANG XianJun | 2012 | Chinese Science Bulletin2012，57，34： | 1 |
| 8 | Controllable growth of GeSi nanostructures by molecular beam epitaxy显示文摘We present an overview on the recent progress achieved on the controllable growth of diverse GeSi alloy nanostructures by molecular beam epitaxy. Prevailing theories for controlled growth of Ge nanostructures on patterned as well as inclined Si surfaces are outlined firstly, followed by reviews on the preferential growth of Ge nanoislands on patterned Si substrates, Ge nanowires and high density nanoislands grown on inclined Si surfaces,and the readily tunable Ge nanostructures on Si nanopillars. Ge nanostructures with controlled geometries, spatial distributions and densities, including two-dimensional ordered nanoislands, three-dimensional ordered quantum dot crystals, ordered nanorings, coupled quantum dot molecules, ordered nanowires and nanopillar alloys, are discussed in detail. A single Ge quantum dot-photonic crystal microcavity coupled optical emission device demonstration fabricated by using the preferentially grown Ge nanoisland technique is also introduced. Finally, we summarize the current technology status with a look at the future development trends and application challenges for controllable growth of Ge nanostructures. | Yingjie Ma Tong Zhou Zhenyang Zhong Zuimin Jiang | 2018 | Journal of Semiconductors2018，39，6： | 1 |
| 9 | Microbial diversity in lake sediments detected by PCR-DGGE显示文摘In this study,PCR-denaturing gradient gel electrophoresis(DGGE)was applied to analyze the microbial communities in lake sediments from Lake Xuanwu,Lake Mochou in Nanjing and Lake Taihu in Wuxi.Sediment samples from seven locations in three lakes were collected and their genomic DNAs were extracted.The DNA yields of the sediments of Lake Xuanwu and Lake Mochou were high(10 mg/g),while that of sediments in Lake Taihu was relatively low.After DNA purification,the 16S rDNA genes(V3 to V5 region)were amplified and the amplified DNA fragments were separated by parallel DGGE.The DGGE profiles showed that there were five common bands in all the lake sediment samples indicating that there were similarities among the populations of microorganisms in all the lake sediments.The DGGE profiles of Lake Xuanwu and Lake Mochou were similar and about 20 types of micro-organisms were identified in the sediment samples of both lakes.These results suggest that the sediment samples of these two city lakes(Xuanwu,Mochou)have similar microbial communities.However,the DGGE profiles of sediment samples in Lake Taihu were significantly different from these two lakes.Furthermore,the DGGE profiles of sediment samples in different locations in Lake Taihu were also different,suggesting that the microbial communities in Lake Taihu are more diversified than those in Lake Xuanwu and Lake Mochou.The differences in microbial diversity may be caused by the different environmental conditions,such as redox potential,pH,and the concentrations of organic matters.Seven major bands of 16S rDNA genes fragments from the DGGE profiles of sediment samples were further reamplified and sequenced.The results of sequencing analysis indicate that five sequences shared 99%-100%homology with known sequences(Bacillus and Brevibacillus,uncultured bacteria),while the other two sequences shared 93%-96%homology with known sequences(Acinetobacter,and Bacillus).The study shows that the PCR-DGGE technique combined with sequence analysis is a feasible and efficient method for the determination of microbial communities in sediment samples. | Xinqing ZHAO Liuyan YANG Can CHEN Lin XIAO Lijuan JIANG Zhe MA Haowei ZHU Zhenyang YU Daqiang YIN | 2008 | Frontiers in Biology2008，3，3： | 0 |
| 10 | Oxygen-modulated metal nitride clusters with moderate binding ability to insoluble Li_(2)S_(x) for reversible polysulfide electrocatalysis显示文摘Multiphase sulfur redox reactions with advanced homogeneous and heterogeneous electrochemical processes in lithium–sulfur(Li–S)batteries possess sluggish kinetics.The slow kinetics leads to significant capacity decay during charge/discharge processes.Therefore,electrocatalysts with adequate sulfurredox properties are required to accelerate reversible polysulfide conversion in cathodes.In this study,we have fabricated an oxygen-modulated metal nitride cluster(C-MoN_(x)-O)that has a moderate binding ability to the insoluble Li_(2)S_(x)for reversible polysulfide electrocatalysis.A Li–S battery equipped with CMoN_(x)-O electrocatalyst displayed a high discharge capacity of 875 mAh g^(-1)at 0.5 C.The capacity decay rate of each cycle was only 0.10%after 280 cycles,which is much lower than the control groups(C-MoO_(x):0.16%;C-MoN_(x):0.21%).Kinetic studies and theoretical calculations suggest that C-MoN_(x)-O electrocatalyst presents a moderate binding ability to the insoluble Li_(2)S_(2)and Li_(2)S when compared to the C-MoO_(x)and C-MoN_(x)surfaces.Thus,the C-MoN_(x)-O can effectively immobilize and reversibly catalyze the solid–solid conversion of Li_(2)S_(2)–Li_(2)S during charge–discharge cycling,thus promoting reaction kinetics and eliminating the shuttle effect.This study to design oxygen-doped metal nitrides provides innovative structures and reversible solid–solid conversions to overcome the sluggish redox chemistry of polysulfides. | Menghao Cheng Zhenyu Xing Rui Yan Zhenyang Zhao Tian Ma Mi Zhou Xikui Liu Shuang Li Chong Cheng | 2023 | InfoMat2023，5，4： | 0 |
| 11 | PIV Measurements of Coolant Flow Field in a Diesel Engine Cylinder Head显示文摘This paper presents experimental measurements of coolant flow field in the water jacket of a diesel engine cylinder head. The test was conducted at three different flow rates using a 2-D PIV system. Appropriate tracing particles were selected and delivery device was designed and manufactured before the test. The flow parameters, such as velocity, vorticity and turbulence, were used to analyze the flow field. The effects of vortex which was located between the intake valve and the exhaust valve were discussed. The experimental results showed an asymmetric distribution of velocity in the water jacket. This led to an asymmetric thermal distribution, which would shorten the service life of the cylinder head. The structure optimization to the water jacket of cylinder head was proposed in this paper. The experimental system, especially the 2-D PIV system, is a great help to study the coolant flow structure and analyze cooling mechanism in the diesel engine cylinder head. | MA Hongwei ZHANG Zhenyang XUE Cheng HUANG Yunlong | 2015 | Journal of Thermal Science2015，24，2： | 0 |
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