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Field observation of wave overtopping at sea dike using shore-based video images

Journal of Hydrodynamics 2021年第4期33卷 657-672页

作者： Shan-hang Chi Chi Zhang ti-ti Sui Zhu-bin Cao Jin-hai Zheng Jiang-shan Fan State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai UniversityNanjing210098China Key Laboratory of Ministry of Education for Coastal Disaster and Protection Hohai UniversityNanjing210098China College of Harbour Coastal and Offshore EngineeringHohai UniversityNanjing210098China Rizhao Port Group Co. Ltd.Rizhao276826China

Wave overtopping at a sea dike was observed using video images during a storm in July 2018 at Rizhao Coast,China.A shore-based video monitoring system was mounted to collect coastal images with a sample frequency of 1 Hz in the beginning 10 min of each hour during daylight.A method to extract the frequency,location,width and duration of individual overtopping events based on the shore-based video monitoring system was developed.A total of 6252 individual overtopping events were detected over a 360m long sea dike during the storm of 10 h in a safe and labor-saving way,enabling a detailed analysis of the temporal and spatial variation of wave *** temporal variation of overtopping duration,frequency and volume is basically in sync with the change of tidal level(R=0.87,0.82 and 0.76,respectively).The increase of wave height increases the overtopping frequency *** found a high correlation between the hourly observed data and the predicted results of two commonly used *** the previous field measurements of overtopping that were limited in a single location,significant spatial variation of overtopping in the alongshore direction is *** overtopping volume varies with a factor of 6 within the range of several wave *** is further revealed that the spatial variation of overtopping is highly correlated with the alongshore variation of surf zone width with a correlation coefficient of *** present study suggests the feasibility of shore-based video monitoring technique to capture the main features of wave overtopping at coastal dikes,providing new possibilities to monitor wave overtopping in the field and to improve prediction tools.

关键词： Wave overtopping coastal video monitoring field measurement temporal and spatial variations storm events

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“Transient”or“Persistent”Coding for Working Memory

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Neuroscience Bulletin 2020年第10期36卷 1233-1235页

作者： Yixuan Ku ti-Fei Yuan Guangdong Provincial Key Laboratory of Social Cognitive Neuroscience and Mental Health Department of PsychologySun Yat-sen UniversityGuangzhou 510006China Peng Cheng Laboratory Shenzhen 518040China Shanghai Key Laboratory of Psychotic Disorders Shanghai Mental Health CenterShanghai Jiao Tong University School of MedicineShanghai 200030China Co-innovation Center of Neuroregeneration Nantong UniversityNantong 226001China

Working memory(WM)maintains information temporarily for subsequent goal-directed behaviors,such as remembering a telephone number to *** serves as a supporting mental workspace for many cognitive functions such as mental calculation,reading,and learning new *** critical role of persistent activity in the prefrontal cortex in WM,originally proposed to bridge sensory information and motor responses[1],has been severely debated recently[2,3].

关键词： telephone such tempo

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Estimating rice paddy areas in China using multi-temporal cloud-free normalized difference vegetation index (NDVI) imagery based on change detection

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Pedosphere 2020年第6期30卷 734-746页

作者： Bolun LI Chaopu ti Xiaoyuan YAN State Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China University of Chinese Academy of Sciences Beijing 100049China

The spatial pattern of rice paddies is an essential parameter used for studies of greenhouse gas emissions,agricultural resource management,and environmental *** large spatial scales,previous studies have usually mapped rice paddies using a single vegetation index product based on a traditional classification method,or a combined analysis of various vegetation and water indices derived from the moderate resolution imaging spectroradiometer(MODIS)satellite ***,different indices increase the computational cost and constrain the satellite data sources,and traditional classification methods(e.g.,maximum likelihood classification)may be time-consuming and difficult to carry out over a large area like *** this study,we designed an auto-thresholding and single vegetation index(normalized difference vegetation index(NDVI))-based procedure to estimate the spatial distribution of rice paddies in *** MOD09Q1 product,which was available at MODIS’s highest spatial resolution(250 m),was taken as the input *** auto-threshold function was also introduced into the change detection process to distinguish rice paddies from other *** MODIS-derived maps were validated with ground surveys and then compared with China national statistical data of rice paddy *** results indicated that the best classification result was achieved for plain regions,and that the accuracy declined for hilly regions,where the complex landscape could lead to an underestimation of the rice paddy area.A comparison between the modeled results and other analyses using 500-m MODIS data suggests that rice paddies may be identified routinely using a single vegetation index with finer resolution on large spatial scales.

关键词： HANTS algorithm moderate resolution imaging spectroradiometer(MODIS) land surface water index Otsu’s algorithm rice cultivation

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Feasibility of semi-solid die casting of ADC12 aluminum alloy

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Transactions of Nonferrous Metals Society of China 2010年第9期20卷 1756-1762页

作者： S.JANUDOM T.RATTANOCHAIKUL R.bura PA S.WISUTMETHANGOON J.WANNASIN Department of Mining and Materials Engineering Faculty of EngineeringPrince of Songkla University Department of Industrial Engineering Faculty of Engineering Rajamangala University of Technology Srivijaya Department of Mechanical Engineering Faculty of EngineeringPrince of Songkla University

The feasibility of semi-solid die casting of ADC12 aluminum alloy was studied. The effects of plunger speed, gate thickness, and solid fraction of the slurry on the defects were determined. The defects investigated are gas and shrinkage porosity. In the experiments, semi-solid slurry was prepared by the gas-induced semi-solid （GISS） technique. Then, the slurry was transferred to the shot sleeve and injected into the die. The die and shot sleeve temperatures were kept at 180 ℃ and 250 ℃, respectively. The results show that the samples produced by the GISS die casting give little porosity, no blister and uniform microstructure. From all the results, it can be concluded that the GISS process is feasible to apply in the ADC12 aluminum die casting process. In addition, the GISS process can give improved properties such as decreased porosity and increased microstructure uniformity.

关键词： ADC12 aluminum alloys semi-solid die casting gas induced semi-solid (GISS) rheocasting

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A Single-legged Robot Inspired by the Jumping Mechanism of Click Beetles and Its Hopping Dynamics Analysis

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Journal of Bionic Engineering 2020年第6期17卷 1109-1125页

作者： Gang Chen Jiajun Tu Xiaocong ti Huosheng Hu Faculty of Mechanical Engineering and Automation Zhejiang Sci-Tech UniversityHangzhou 310018China School of Computer Science and Electronic Engineering University of EssexColchester C043SQUK

The click beetle can jump up with a hinge when it is on the dorsal *** jumping mechanism is simple and suitable as an inspiration for designing a simple,small,and reliable hopping *** report a single-legged robot inspired by the jumping mechanism of click *** is 85 mm high,60 mm long,and 41 mm wide,and weighs about 49 *** robot has good hopping performance that the hopping height is about 4 times-4.3 times of its body *** is capable for rescue missions that require to enter enclosed spaces through cracks and narrow *** addition,hopping dynamics of the robot is important to understand its jumping mechanism and improve the robot’s hopping *** existing dynamic study does not complete the analysis including all stages in the hopping which are pre-hopping,take-off,and *** propose the decomposition method to study dynamics of the three stages separately,and synthesize them with related *** dynamic synthesis of multi-motion states in a hopping cycle of the single-legged hopping robot is *** hopping performance and dynamic synthesis theory of the robot are verified by simulations and *** study helps lay the foundation for design and hopping control of simple hopping robot systems.

关键词： single-legged hopping robots hopping cycle dynamics synthesis multi-motion states jumping mechanism imitaion of click beetles

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Inorganic A‑site cations improve the performance of band‑edge carriers in lead halide perovskites

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Frontiers of Optoelectronics 2023年第3期16卷 115-121页

作者： Cheng Wang Yaoguang Rong ti Wang Key Laboratory of Artifcial Micro-and Nano-Structures of Ministry of Education School of Physics and TechnologyWuhan UniversityWuhan 430072China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China

In lead halide perovskites,organic A-site cations are generally introduced to fne-tune the *** of the questions under debate is whether organic A-site cations are essential for high-performance solar *** this study,we compare the band edge carrier dynamics and difusion process in MAPbBr_(3)and CsPbBr_(3)single-crystal *** transient absorption microscopy,the band-edge carrier difusion constants are *** the replacement of inorganic A-site cations,the difusion constant in CsPbBr_(3)increases almost 8 times compared to that in MAPbBr_(3).This work reveals that introducing inorganic A-site cations can lead to a much larger difusion length and improve the performance of band-edge carriers.

关键词： Perovskite Inorganic cations Carrier difusion

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Operational Risk-averse Routing Optimization for Cyber-physical Power Systems

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CSEE Journal of Power and Energy Systems 2022年第3期8卷 801-811页

作者： Baozhong ti Jianxiao Wang Gengyin Li Ming Zhou State Key Laboratory of Alternate Electrical Power System with Renew-able Energy Sources North China Electric Power UniversityBeijing 102206China

The extensive application of modern information and communication technology in the power system through the in-depth integration of the information system and the power system has led to the gradual development of the cyberphysical power system(CPPS).While advanced information technology increases the safety and reliability of power system operations,it also increases the risks of fault *** improve the reliability of CPPS from the perspective of power communication routing,it is proposed that the CPPS model and vulnerability assessment of power node reflect the correlation between information and energy flows with the service impact on power grid operation,which is an important index for evaluating communication *** to the distribution of services at the different important levels on the links,the importance of the cross-layer link is established as the vulnerability evaluation index of the communication ***,the routing optimization model is proposed in combination with the service transmission risk under cyber-attack and the operating characteristics of the information system,which is solved through an improved fast-convergent genetic *** simulation results show that the proposed method allocates the alternate route to the low-risk link without significantly increasing the delay of the main route,which effectively improves the power supply reliability of CPPS in extreme cyber-attack scenarios.

关键词： Comprehensive balanced degree cross-layer link importance cyber-attack cyber-physical power system routing optimization model service importance

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Graphene Fibers: Advancing Applications in Sensor, Energy Storage and Conversion

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Chinese Journal of Polymer Science 2019年第6期37卷 535-547页

作者： Guan-Hang Yu Qing Han Liang-ti Qu Beijing Key Laboratory of Photoelectronic/Electrophotonic Conversion Materials Key Laboratory of Cluster Science Ministry of Education School of Chemistry Beijing Institute of Technology

Graphene fibers are a kind of novel carbon fibers assembled by orderly aligned graphene sheets with high flexibility, good conductivity, high thermal conductivity, and low density, which make them possible to be widely used in high-performance and multifunctional compound materials as well as flexible electronic devices. In this review, we summarize the research progress in the synthesis of graphene fibers, and their applications in sensor, energy storage, and energy conversion. Furthermore, the current issues and some prospects for the future trend of graphene fibers are discussed.

关键词： Graphene fibers Assembly Functionalization Sensor Energy storage and conversion

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A special kind of local structure in the CMB intensity maps: duel peak structure

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Chinese Journal of Astronomy and Astrophysics 2009年第3期9卷 302-306页

作者： Hao Liu ti-Pei Li Key Laboratory of Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing 100049 China Graduate School of Chinese Academy of Sciences Beijing 100039 China Department of Physics ＆ Center for Astrophysics Tsinghua University Beijing 100084 China Department of Engineering Physics ＆ Center for Astrophysics Tsinghua University Beijing100084 China

We study the local structure of Cosmic Microwave Background （CMB） temperature maps released by the Wilkinson Microwave Anisotropy Probe （WMAP） team, and find a new kind of structure, which can be described as follows： a peak （or valley） of average temperature is often followed by a peak of temperature fluctuation that is 4° away. This structure is important for the following reasons： both the well known cold spot detected by Cruz et al. and the hot spot detected by Vielva et al. with the same technology （the third spot in their article） have such structure; more spots that are similar to them can be found on CMB maps and they also tend to be significant cold/hot spots; if we change the 4° characteristic into an artificial one, such as 3° or 5°, there will be less ＂similar spots＂, and the temperature peaks or valleys will be less significant. The presented ＂sim- ilar spots＂ have passed a strict consistency test which requires them to be significant on at least three different CMB temperature maps. We hope that this article could arouse some interest in the relationship of average temperature with temperature fluctuation in local areas; meanwhile, we are also trying to find an explanation for it which might be important to CMB observation and theory.

关键词： cosmic microwave background -- cosmology observations - methods data analysis

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Hamiltonian Gromov–Witten Invariants on C^n+1 with S^1-action

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Acta Mathematica Sinica,English Series 2016年第3期32卷 309-330页

作者： ti Yao LI Bo Hui CHEN Department of Mathematics Sichuan University Chengdu 610064 P. R. China School of Mathematical Sciences Chongqing Normal University Chongqing 401331 P. R. China Department of Mathematics and Yangtze Mathematical Center Sichuan University Chengdu 610064 P. R. China

Consider a Hamiltonian action of S1 on （Cn^n＋1,ωstd）, we shown that the Hamiltonian Gromov-Witten invariants of it are well-defined. After computing the Hamiltonian Gromov-Witten invariants of it, we construct a ring homomorphism from HS1,CR（X, R） to the small orbifold quantum cohomology of X//rS^1 and obtain a simpler formula of the Gromov-Witten invariants for weighted projective space.

关键词： Hamiltonian Gromov-Witten invariants orbifold Gromov-Witten invariants weighted projective space

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