15 results on '"Zeng, Fei"'
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2. Enhanced Coupling Coefficient in Dual-Mode ZnO/SiC Surface Acoustic Wave Devices with Partially Etched Piezoelectric Layer
- Author
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Junyao Shen, Rongxuan Su, Zeng Fei, Huiping Xu, Feng Pan, Sulei Fu, and Cheng Song
- Subjects
SiC ,Technology ,Materials science ,QH301-705.5 ,QC1-999 ,02 engineering and technology ,01 natural sciences ,surface acoustic wave ,Etching (microfabrication) ,0103 physical sciences ,Miniaturization ,General Materials Science ,Particle velocity ,Biology (General) ,Instrumentation ,QD1-999 ,010302 applied physics ,Fluid Flow and Transfer Processes ,business.industry ,multilayer ,Process Chemistry and Technology ,Physics ,Surface acoustic wave ,Bandwidth (signal processing) ,General Engineering ,021001 nanoscience & nanotechnology ,Engineering (General). Civil engineering (General) ,coupling factor ,Piezoelectricity ,Computer Science Applications ,Chemistry ,Electrode ,ZnO ,Optoelectronics ,TA1-2040 ,0210 nano-technology ,business ,Coupling coefficient of resonators - Abstract
Surface acoustic wave (SAW) devices based on multi-layer structures have been widely used in filters and sensors. The electromechanical coupling factor (K2), which reflects energy-conversion efficiency, directly determines the bandwidth of the filter and the sensitivity of sensor. In this work, a new configuration of dual-mode (quasi-Rayleigh and quasi-Sezawa) SAW devices on a ZnO/SiC layered structure exhibiting significantly enhanced K2 was studied using the finite element method (FEM), which features in the partial etching of the piezoelectric film between the adjacent interdigitated electrodes (IDTs). The influences of piezoelectric film thickness, etching ratio, top electrodes, bottom electrodes, and the metallization ratio on the K2 were systematically investigated. The optimum K2 for the quasi-Rayleigh mode and quasi-Sezawa mode can exceed 12% and 8%, respectively, which increases by nearly 12 times and 2 times that of the conventional ZnO/SiC structure. Such significantly promoted K2 is of great benefit for better comprehensive performance of SAW devices. More specifically, a quasi-Rayleigh mode with relatively low acoustic velocity (Vp) can be applied into the miniaturization of SAW devices, while a quasi-Sezawa mode exhibiting a Vp value higher than 5000 m/s is suitable for fabricating SAW devices requiring high frequency and large bandwidth. This novel structure has proposed a viable route for fabricating SAW devices with excellent overall performance.
- Published
- 2021
- Full Text
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3. A novel 3D profile measurement method based on digital photoelastic technology
- Author
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Xu Shuang, Guanjun Chen, Zeng Fei, Gongfa Li, and Bo Tao
- Subjects
Measurement method ,Series (mathematics) ,Computer science ,business.industry ,Phase (waves) ,Phase unwrapping ,law.invention ,Reference plane ,Stress field ,Optics ,Projector ,law ,Pattern sequence ,business - Abstract
A three-dimensional profile measurement method based on digital photoelastic fringe analysis technology is proposed in this paper. According to the actual stress field of a disc under appropriate load, the photoelastic fringe patterns are generated. These patterns are illuminated on the reference plane and objects through a projector, which are regarded as the structured-light pattern sequence. Then a series of images including normal images and deformed fringe images are captured. These images contain two significant photoelastic parameters, isoclinic parameter and isochromatic parameter, which could be evaluated by the phase shifting method. Therefore, phase differences can be calculated by photoelastic isochromatic parameter after phase unwrapping. Depth information is carried in the phase differences and virtual 3D profile equal to real objects could be reconstructed. Experiments demonstrate that this method is robust and suitable for measuring objects with regular and general shape.
- Published
- 2019
4. Dynamic optimizations of Monte Carlo simulation to assess locational capacity, transmission, and market parameters
- Author
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Rau, Narayan S. and Zeng, Fei
- Subjects
Monte Carlo method -- Analysis ,Electric power transmission -- Management ,Electric power systems -- Electric losses ,Electric power systems -- Management ,Company business management ,Business ,Electronics ,Electronics and electrical industries - Abstract
Risk indices of loss-of-load expectation and loss-of-energy expectation were traditionally used to determine generation adequacy. However, because responsibility of generation installation and transmission upgrades rests with different entities, both generation and transmission need to be examined to evaluate the resource adequacy of today's deregulated power systems. Further, it is important to delineate the contribution to curtailments arising from insufficient installed capacity and bottlenecks in transmission system. Hence, risk-based planning and market decision-makings have to address both generation and transmission jointly. This paper presents a procedure to combine dynamic optimization and Monte Carlo simulation to generate a vector space of solution, from which optimal solutions for different objectives can then be easily obtained. Determining locational capacity and transmission requirements serves the example of such an application. This paper closes with a discussion on some possible changes to risk criteria. Index Terms--Installed capacity, loss-of-load expectation (LOLE), optimization, reliability, risk, transfer capability.
- Published
- 2006
5. Adequacy and responsibility of locational generation and transmission--optimization procedures
- Author
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Rau, Narayan S. and Zeng, Fei
- Subjects
Electric utilities -- Research ,Business ,Electronics ,Electronics and electrical industries - Abstract
Under the deregulated environment of electric power industry, generation can be installed anywhere in the system resulting in an 'imbalance' between the generation and transmission. Shortages of generation in some subregions result in 'bottlenecks' within a system raising reliability concerns regarding subregional adequacy. Excess of generation capacity raises the issue of how much capacity in which location is entitled to receive payments for installed capacity. Therefore, there is a need to determine locational requirement for both generation and transmission such that assistance to subregions under random generator outages is not restricted. This paper presents optimization procedures for the determination of adequacy and responsibility for locational generation and transmission. The outlined procedures applicable to situations of planning to identify additional needs as well as to situations of market design for installed capacity in subregions. The paper closes by a discussion of forward auctions for the procurement of capacity in subregions. Index Terms--Installed capacity, loss of load expectation, optimization, reliability, risk, transfer capability.
- Published
- 2004
6. Image Segmentation Technology Based on Genetic Algorithm
- Author
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Bo Tao, Zeng Fei, Chong Tan, Ying Sun, Gongfa Li, and Xu Shuang
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Computer science ,business.industry ,media_common.quotation_subject ,ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION ,020206 networking & telecommunications ,Pattern recognition ,Image processing ,02 engineering and technology ,Image segmentation ,Adaptability ,Digital image ,Robustness (computer science) ,0202 electrical engineering, electronic engineering, information engineering ,Image segmentation algorithm ,Segmentation ,Artificial intelligence ,business ,MATLAB ,computer ,media_common ,computer.programming_language - Abstract
Image segmentation technology is one of the important topics in the field of digital image research. However, there is no uniform standard for existing image segmentation methods, and the traditional image segmentation method is only suitable for some specific occasions. Therefore, it is very urgent to research and develop new theories and methods of image segmentation technology. Genetic algorithm is a method for calculating the optimal solution by simulating the biological evolution process in the natural selection and genetic mechanism of biological evolution. It has strong robustness, parallelism, adaptability and fast convergence. It can be applied in image segmentation technology to determine the segmentation threshold. Therefore, this paper studies the image segmentation based on genetic algorithm, and compares different image segmentation algorithms. The experimental results show that the image segmentation effect based on genetic algorithm is better than the traditional image segmentation.
- Published
- 2019
7. Systematical Study of the Basic Properties of Surface Acoustic Wave Devices Based on ZnO and GaN Multilayers
- Author
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Zeng Fei, Feng Pan, Cheng Song, Huiping Xu, Sulei Fu, Rongxuan Su, and Junyao Shen
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Electromechanical coupling coefficient ,Materials science ,Computer Networks and Communications ,Multiphysics ,lcsh:TK7800-8360 ,02 engineering and technology ,01 natural sciences ,surface acoustic wave ,GaN ,Crystal ,0103 physical sciences ,Electrical and Electronic Engineering ,Thin film ,010302 applied physics ,multilayer ,business.industry ,lcsh:Electronics ,Surface acoustic wave ,021001 nanoscience & nanotechnology ,2-D electron gas ,Hardware and Architecture ,Control and Systems Engineering ,Signal Processing ,ZnO ,Optoelectronics ,Phase velocity ,0210 nano-technology ,business ,Fermi gas - Abstract
Recently, surface acoustic wave (SAW) devices based on layered structures are a popular area of research. Multilayered structures, including ZnO and GaN, have shown great performance and can be applied in diverse fields. Meanwhile, thin films, such as AlGaN and n-ZnO, can be added to these structures to form a 2-D electron gas (2DEG) which makes the devices tunable. This work systematically studies the basic properties of SAW devices based on ZnO and GaN multilayers via COMSOL Multiphysics. The sorts of structures with different crystal orientations are simulated, and various acoustic modes are considered. Results show that a range of phase velocity from about 2700 m/s to 6500 m/s can be achieved, and devices based on ZnO and GaN multilayers can meet the requirements of the electromechanical coupling coefficient from about 0 to 7%. Every structure&rsquo, s unique properties are valuable for diverse applications. For example, c-ZnO/c-GaN/c-sapphire structure can be used for high-frequency and large-bandwidth SAW devices, while SAW devices based on a-ZnO/a-GaN/r-sapphire and 2DEG are suitable for programmable SAW sensors. This work has great reference value for future research into SAW devices.
- Published
- 2020
8. A fuzzy Petri net based approach for fault diagnosis in power systems considering temporal constraints
- Author
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Chung-Li Tseng, Fushuan Wen, Yong Zhang, Yubo Yuan, Chi Yung Chung, Xiaoyi Zhang, Yan Zhang, and Zeng Fei
- Subjects
Engineering ,Event (computing) ,business.industry ,020209 energy ,Distributed computing ,Energy Engineering and Power Technology ,Topology (electrical circuits) ,02 engineering and technology ,Petri net ,Fault (power engineering) ,Reliability engineering ,Constraint (information theory) ,Matrix (mathematics) ,Electric power system ,Identification (information) ,0202 electrical engineering, electronic engineering, information engineering ,020201 artificial intelligence & image processing ,Electrical and Electronic Engineering ,business - Abstract
The fuzzy Petri net is a promising and efficient approach that can tackle the complexities of power system fault diagnosis. In this work, the temporal constraint between event occurrences in power systems is investigated. Then, it is introduced to a fuzzy Petri net (FPN) for fault diagnosis. The temporal attributes are assigned to the propositions in the Petri net, so that temporal information can be taken into account, which makes the true hypothesis distinguishable from the false ones. The modified matrix execution algorithm can enhance computational efficiency, with a “weighted average” operation included to improve the fault-tolerance. The developed model possesses a modular structure, which is easy to adapt to topology changes, and to accommodate modern protection schemes. A preliminary evaluation of the operating performance of protective devices is also carried out after fault section identification. The testing results on the IEEE 14-bus power system and Zhejiang provincial power system in China demonstrate that the developed model is correct and efficient. Compared with three existing fault diagnosis methods, the proposed one has stronger fault-tolerance with lower computational cost, and is suitable for on-line fault diagnosis in large-scale power systems.
- Published
- 2016
9. Development status and trend of airborne laser communication terminals
- Author
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张 鑫 Zhang Xin, 曾 飞 Zeng Fei, 高世杰 Gao Shi-Jie, and 伞晓刚 San Xiao-Gang
- Subjects
010309 optics ,020210 optoelectronics & photonics ,Computer science ,business.industry ,0103 physical sciences ,0202 electrical engineering, electronic engineering, information engineering ,02 engineering and technology ,Telecommunications ,business ,01 natural sciences ,Atomic and Molecular Physics, and Optics ,Free-space optical communication - Published
- 2016
10. Waveguide holographic head-mounted display technology
- Author
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张新 Zhang Xin and 曾飞 Zeng Fei
- Subjects
Physics ,Optics ,business.industry ,law ,General Engineering ,Holography ,Holographic display ,Waveguide (acoustics) ,Optical head-mounted display ,business ,law.invention - Published
- 2014
11. Improved method to fully compensate the spatial phase nonuniformity of LCoS devices with a Fizeau interferometer
- Author
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Lei Sheng, Yanfeng Qiao, Shijie Gao, Zeng Fei, and Qiang Lu
- Subjects
Wavefront ,Fizeau interferometer ,Materials science ,business.industry ,Materials Science (miscellaneous) ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Residual ,01 natural sciences ,Industrial and Manufacturing Engineering ,010309 optics ,Liquid crystal on silicon ,Optics ,Liquid crystal ,Frequency domain ,0103 physical sciences ,Business and International Management ,0210 nano-technology ,business ,Phase modulation ,Voltage - Abstract
Liquid crystal on silicon (LCoS) devices usually show spatial phase nonuniformity (SPNU) in applications of phase modulation, which comprises the phase retardance nonuniformity (PRNU) as a function of the applied voltage and inherent wavefront distortion (WFD) introduced by the device itself. We propose a multipoint calibration method utilizing a Fizeau interferometer to compensate SPNU of the device. Calibration of PRNU is realized by defining a grid of 3×6 cells onto the aperture and then calculating phase retardance of each cell versus a gradient gray pattern. With designing an adjusted gray pattern calculated by the calibrated multipoint phase retardance function, compensation of inherent WFD is achieved. The peak-to-valley (PV) value of the residual WFD compensated by the multipoint calibration method is significantly reduced from 2.5λ to 0.140λ, while the PV value of the residual WFD after global calibration is reduced to 0.364λ. Experimental results of the generated finite-energy 2D Airy beams in Fourier space demonstrate the effectiveness of this multipoint calibration method.
- Published
- 2016
12. 3D reconstruction of material transportation status on belt conveyors
- Author
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Li Zilong, Yue Zhangsi, Zeng Fei, and Qing Wu
- Subjects
Laser scanning ,business.industry ,Computer science ,Delaunay triangulation ,Contour line ,OpenGL ,Computer vision ,Artificial intelligence ,Solid modeling ,business ,Material flow ,Visualization ,Data modeling - Abstract
Real timely, intuitively monitoring the transportation status of material flow is a fundamental basis on belt conveyor speed control operation. To improve the detection precision and visualization degree, the article presents a method on 3D reconstruction of material transportation status on belt conveyor. A Laser Scanner LMS291-S05 is used to acquire a serials of 2D contour lines in real time, combined with velocity sensors to match the third coordinate of the 2D contour lines, making 3D points cloud data of the contour of material flow obtained. Based on Visual C++ 6.0 and OpenGL, Delaunay triangulation mesh is adopted to 3D reconstruct the points cloud. Applying the system to monitor the transportation status of hematite ore running at a constant speed on belt conveyor, the result shows that the method can effectively reconstruct the acquired data and obtain the 3D model of material flow, providing important data for reducing energy consumption in belt conveyor speed control strategy.
- Published
- 2015
13. A new strategy for optimal PMU placement based on limited exhaustive approach
- Author
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Xiaoyi Zhang, Yubo Yuan, Daonong Zhang, Hao Xu, and Zeng Fei
- Subjects
Engineering ,Mathematical optimization ,business.industry ,business - Published
- 2014
14. Influence of Sky Background Radiation on Bit Error Rate of Atmospheric Laser Communication System
- Author
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乔彦峰 Qiao Yan-feng, 鲁强 Lu Qiang, 曾飞 Zeng Fei, 张鑫 Zhang Xin, and 张玉良 Zhang Yuliang
- Subjects
Physics ,Optics ,business.industry ,Sky ,media_common.quotation_subject ,Bit error rate ,Electrical and Electronic Engineering ,business ,Atomic and Molecular Physics, and Optics ,Free-space optical communication ,Remote sensing ,media_common ,Background radiation - Published
- 2016
15. Holographic Waveguide Head-Mounted Display System Design Based on Prisms-Grating Structure
- Author
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史广维 Shi Guang-wei, 张继真 Zhang Jizhen, 张建萍 Zhang Jian-ping, 曲贺盟 Qu Hemeng, 曾飞 Zeng Fei, and 张新 Zhang Xin
- Subjects
Optics ,Materials science ,business.industry ,law ,Holography ,Optical head-mounted display ,Systems design ,Waveguide (acoustics) ,Grating ,business ,Atomic and Molecular Physics, and Optics ,Electronic, Optical and Magnetic Materials ,law.invention - Published
- 2013
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