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Preliminary analysis of echolocation signals produced by fleeing Irrawaddy dolphins(Orcaella brevirostris)

Acta Oceanologica Sinica 2019年第1期38卷 85-89页

作者： Ying Jiang Xuelei Zhang Zhiguo Yang Saifullah Arifin Jaaman Qinzeng Xu Azmi Marzuki Muda Hairul Masrini Muhamad First Institute of Oceanography Ministry of Natural Resources Laboratory for Regional Oceanography and Numerical Modeling Pilot National Laboratory for Marine Science and Technology (Qingdao) Laboratory for Marine Ecology and Environmental Science Pilot National Laboratory for Marine Science and Technology (Qingdao) China National Deep Sea Center Ministry of Natural Resources Institute of Oceanography & Environment University Malaysia Terengganu Key Laboratory of Underwater Acoustics and Marine Information Technology Department of Applied Marine Physics & Engineering College of Ocean and Earth Xiamen University

In this study, echolocation signals were recorded from a wild Irrawaddy dolphin(Orcaella brevirostris) in shallow water in the Bay of Brunei. During sound recording, a small fishing boat engine startled a nearby Irrawaddy dolphin and began chasing it on two occasions. Variations in the acoustic parameters were detected. When the Irrawaddy dolphin was startled and chased, the sound pressure level, number of click trains per minute, pulse number, and average inter-pulse interval(PI) per click train were all affected. The PI increased and exhibited a slight downward trend during the chase. The increase in PI indicated an increase in the inspection distance as the dolphin escaped. Thus, Irrawaddy dolphins may adapt their echolocation signals to stand out from ambient noise in the wild and to improve their search efforts in potentially risky situations. Appropriate management of the burst noise around the dolphins is important.

关键词： click train echolocation signal Irrawaddy dolphin signal change

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Study of RF structure for W band sheet beam EIK

Study of RF structure for W band sheet beam EIK

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IET International Radar Conference 2015

作者： Shuyuan Chen Zhiye Jiang Jiaqi Liu Lu Gao Jingliang Bai Hongyan Liu Gang Meng Feng Xu Hu Li Chengguo Liu Guangsheng Zhu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing 100076 P. R. China

Microwave tubes are vacuum electron devices used for the generation and amplification of radio frequencies in the microwave frequency range. Klystron is a kind of microwave tubes which is used in radar. A sheet-beam Extended Interaction Klystron (SBEIK) is an attractive MMW amplifier because of its high gain per unit length and compact configuration. The RF structure is an important part of the whole tube, which is used for beam wave interaction. In this paper, two kinds of barbell cavity has been studied. The difference between the separating multi-gap barbell resonant cavity and the strong coupling multi-gap barbell cavity has been discussed. RF parameters have been calculated by 3D simulations.

关键词： EIK Klystron Microwave RF barbell cavity radiofrequency MICROWAVE microwave tubes Barbells Klystrons Electron devices high gain

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Adaptive feed-forward control for seeker based on the disturbance observer

Adaptive feed-forward control for seeker based on the distur...

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IEEE Advanced Information technology, Electronic and Automation Control Conference (IAEAC)

作者： Xin Liu Zhenhong Niu Yi Shu Lian Xue Mingchao Zhu National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematics Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

In order to improve the tracking and stabilization performance, a control method combining disturbance observer and adaptive feed-forward control using parameterization is proposed for seeker stabilized platforms. The system identification algorithm is used to identify dynamic model of the true plant. Then the discrete-time disturbance observer is designed. The feedback loop controller is designed using pole-placement techniques. The recursive least square (RLS) adaptive filter is used to build the inverse model of the feedback control loop and in this way, the feed-forward control is constructed. The adaptive filter and the feedback loop constitute a control scheme with two degrees-of-freedom (DOF). Tracking experiments conducted on velocity command inputs verify the validity of the adaptive feed-forward controller. Experimental results show that this method responses quickly to commands. For a sinusoidal signal at the frequency of 30Hz, the adaptive feed-forward controller can obtain an amplitude response without attenuation and the phase lag is reduced to 11° in contrast with the feedback control whose phase lag is 60°. This method significantly improves the transient performance and is superior to the feedback control alone.

关键词： Adaptive filters Feedback control Disturbance observers Feedforward systems Low pass filters Tracking loops Stability analysis

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Summer Persistence Barrier of Sea Surface Temperature Anomalies in the Central Western North Pacific

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Advances in Atmospheric sciences 2012年第6期29卷 1159-1173页

作者：赵霞李建平张文君 Laboratory of Ocean Circulation and Waves Institute of OceanologyChinese Academy of Sciences National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric PhysicsChinese Academy of Science State Key Laboratory of Tropical Oceanography South China Sea Institute of OceanologyChinese Academy of Sciences Key Laboratory of Meteorological Disaster of Ministry of Education and College of Atmospheric Sciences Nanjing University of Information Science and Technology

The persistence barrier of sea surface temperature anomalies （SSTAs） in the North Pacific was investigated and compared with the ENSO spring persistence barrier. The results show that SSTAs in the central western North Pacific （CWNP） have a persistence barrier in summer： the persistence of SSTAs in the CWNP shows a significant decline in summer regardless of the starting month. Mechanisms of the summer persistence barrier in the CWNP are different from those of the spring persistence barrier of SSTAs in the central and eastern equatorial Pacific. The phase locking of SSTAs to the annual cycle does not explain the CWNP summer persistence barrier. Remote ENSO forcing has little linear influence on the CWNP summer persistence barrier, compared with local upper-ocean process and atmospheric forcing in the North Pacific. Starting in wintertime, SSTAs extend down to the deep winter mixed layer then become sequestered beneath the shallow summer mixed layer, which is decoupled from the surface layer. Thus, wintertime SSTAs do not persist through the following summer. Starting in summertime, persistence of summer SSTAs until autumn can be explained by the atmospheric forcing through a positive SSTAs-cloud/radiation feedback mechanism because the shallow summertime mixed layer is decoupled from the temperature anomalies at depth, then the following autumnwinter-spring, SSTAs persist. Thus, summer SSTAs in the CWNP have a long persistence, showing a significant decline in the following summer. In this way, SSTAs in the CWNP show a persistence barrier in summer regardless of the starting month.

关键词： SST anomalies persistence barrier oceanic mixed layer atmospheric forcing positive cloudfeedback on SSTAs

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A Jamming Decision-Making Method Based on Next State Prediction SAC 6

A Jamming Decision-Making Method Based on Next State Predict...

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6th IEEE International Conference on Electronic Information and Communication technology, ICEICT 2023

作者： Chen, Geng Gao, Jingpeng Zhang, Tianran Jiang, Zhiye Shen, Chen College of Information and Communication Engineering Harbin Engineering University Harbin China Beijing Institute of Electronic System Engineering Beijing100854 China Beijing Institute of Space Long March Vehicle National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

ISBN: (纸本)9798350399059

In light of the growing complexity of the electromagnetic environment, traditional jamming decision-making methods have become less effective due to poor generalization and inefficient jamming performance. This paper proposes a jamming decision-making method based on next state prediction SAC (Soft Actor-Critic) to address this issue. Firstly, we design the state, action, and reward elements under electronic warfare scenarios. Secondly, a next state prediction critic network is proposed to accurately estimate the value function by modeling the environment dynamics and extracting richer representational information. Finally, a negative activation ReLU is introduced to improve the utilization ratio of network parameters. Simulation results show that the proposed method achieves a 98.4% success rate at a distance of 90 km from the radar and a 70.0% success rate at 30 km. Therefore, this method exhibits good adaptability and jamming performance in the field of jamming decision-making. © 2023 IEEE.

关键词： Decision making

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A novel non-enzymatic hydrogen peroxide sensor based on Co:ZnO modified electrodes

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Progress in Natural science:Materials International 2018年第1期28卷 24-27页

作者： Long Wang Tong Wu Han Wu Jun Zhong Ning Wang Rongming Wang Department of Equipment Manufacture Zhongshan Torch Polytechnic National Institute of Metrology China National Computer Products Quality Supervising Test Center Beijing Key Laboratory for Carbon-Based Functional Materials and Devices Institute of Functional Nano and Soft Materials Laboratory (FUNSOM) Soochow University Center for Green Innovation School of Mathematics and Physics University of Science and Technology Beijing

There is currently intense interest in the use of nanoparticles for a wide range of biomedical and technological applications. In this paper, the hierarchical Co doped ZnO nanoflowers were synthesized by a facile wet chemical method and explored as biosensing material. The as-modified novel hydrogen peroxide sensor exhibited a wide linear range（0.25–20 mM）, highly reproducible response（R.S.D. of 2.7%） and long-term stability. The doping Co2+ions carried out the oxidations rapidly and efficiently for the catalysis of hydrogen peroxide（H2O2）. A high activity toward H2O2in the presence of ascorbic acid（AA） and NaNO2, which are only common for natural enzymes, has also been demonstrated. The good analytical performance, low cost and straightforward preparation method makes this doped semiconductor promising for a wide range of potential applications in medicine, biotechnology and environmental chemistry.

关键词： Nonenzymatic H2O2 sensor Co:ZnO Nanoflowers Electrocatalysis

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A Stability Analysis of Hybrid Schemes to Cure Shock Instability

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Communications in Computational physics 2014年第5期15卷 1320-1342页

作者： Zhijun Shen Wei Yan Guangwei Yuan National Key Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational MathematicsP.O.Box 8009-26Beijing 100088China Center for Applied Physics and Technology HEDPSPeking UniversityBeijing 100871China.

The carbuncle phenomenon has been regarded as a spurious solution produced by most of contact-preserving *** hybrid method of combining high resolution flux with more dissipative solver is an attractive attempt to cure this kind of non-physical *** this paper,a matrix-based stability analysis for 2-D Euler equations is performed to explore the cause of instability of numerical *** combining the Roe with HLL flux in different directions and different flux components,we give an interesting explanation to the linear numerical *** on such analysis,some hybrid schemes are compared to illustrate different mechanisms in controlling shock *** experiments are presented to verify our analysis *** conclusion is that the scheme of restricting directly instability source is more stable than other hybrid schemes.

关键词： Godunov methods numerical shock instability hybrid scheme.

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Learning to Infer Weather States Using Partial Observations

Journal of Geophysical Research: Machine Learning and Comput...

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Journal of Geophysical Research: Machine Learning and Computation 2025年第1期2卷

作者： Jie Chao Baoxiang Pan Quanliang Chen Shangshang Yang Jingnan Wang Congyi Nai Yue Zheng Xichen Li Huiling Yuan Xi Chen Bo Lu Ziniu Xiao National Key Laboratory of Earth System Numerical Modeling and Application Institute of Atmospheric Physics Chinese Academy of Science Beijing China School of Atmospheric Sciences Chengdu University of Information Technology Chengdu China Key Laboratory of Mesoscale Severe Weather Ministry of Education and School of Atmospheric Sciences Nanjing University Nanjing China College of Computer National University of Defense Technology Hunan China Clustertech LTD Hong Kong China National Climate Center China Meteorological Administration Beijing China

Accurate state estimation of the high-dimensional, chaotic Earth's atmosphere marks a Sisyphean task, yet is indispensable for initiating weather forecasts and gauging climate variability. While much effort is devoted to assimilating observations and forecasts to infer weather states, the inherent low-dimensional statistical structure in atmospheric circulation, shaped by geophysical laws and geographic boundaries, is underutilized as an informative prior for state inference, or as reference for assessing representative of existing observations and planning new ones. We realize these potential by learning climatological distribution from climate reanalysis/simulation, using a deep generative model. For a case study of estimating 2 m temperature spatial patterns, the learned distribution faithfully reproduces climatology statistics. A combination of the learned climatological prior with few station observations yields strong posterior of spatial pattern estimates, which are spatially coherent, faithful and adaptive to observational constraints, and uncertainty-aware. This allows us to evaluate each observation's value in reducing pattern estimation uncertainty, and guide optimal observation network design by pinpointing the most informative sites. Our study showcases how generative models can extract and utilize information produced in the chaotic evolution of climate system. Deep generative model enables accurate spatial interpolation of weather variables from sparse observations The generative model produces spatially coherent and uncertainty-aware estimates, effectively constrained by observational data The approach provides a framework to quantify observation impact on uncertainty reduction, enabling optimization of observation networks Accurate estimation of weather conditions across a large area is crucial but challenging due to the complex and chaotic nature of the atmosphere. Traditional methods rely on combining observations with forecasts, which can be comp

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Stability analysis of discrete Boltzmann simulation for supersonic flows: Influencing factors, coupling mechanisms and optimization strategies

arXiv

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arXiv 2025年

作者： Wu, Yanhong Gan, Yanbiao Xu, Aiguo Yang, Bin Hebei Key Laboratory of Trans-Media Aerial Underwater Vehicle North China Institute of Aerospace Engineering Langfang065000 China National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics P. O. Box 8009-26 Beijing100088 China National Key Laboratory of Shock Wave and Detonation Physics Mianyang621999 China HEDPS Center for Applied Physics and Technology College of Engineering Peking University Beijing100871 China State Key Laboratory of Explosion Science and Safety Protection Beijing Institute of Technology Beijing100081 China School of Energy and Safety Engineering Tianjin Chengjian University Tianjin300384 China

Supersonic flow simulations encounter challenges in threefold: trans-scale modeling, numerical stability and complex field analysis, due to their inherent nonlinear, nonequilibrium and multiscale characteristics. The discrete Boltzmann method (DBM) provides a multiscale kinetic modeling framework and a set of analysis tools to capture complex discrete/nonequilibrium states and effects. While the stable numerical scheme plays a fundamental role in DBM simulations, a comprehensive and systematic stability analysis remains lacking. Similar to the lattice Boltzmann method, the complexity lies mainly in the intrinsic coupling between velocity and spatiotemporal discretizations, compared with the traditional computational fluid dynamics. Based on the von Neumann stability analysis, we investigate influences of the following aspects: (i) approaches for determining equilibrium distribution functions and designing discrete velocities, (ii) thermodynamic nonequilibrium (TNE) levels, (iii) spatiotemporal discretization schemes, (iv) initial conditions, and (v) model parameters, on the stability of DBM simulation. key findings include: (i) Among the equilibrium distribution discretization methods considered, the moment-matching approach outperforms expansion- and weighting-coefficient-based methods in the test simulations. (ii) As TNE intensity/Knudsen number increases, the nonlinear behavior of the system is enhanced. Accordingly, the intrinsic nonlinearity embedded in the matching model equation increases, regardless of whether the model is kinetic or macroscopic. In numerical simulations, instabilities induced by fast-changing behaviors, such as shock waves, are often amplified by nonlinear terms in the model equation. Therefore, the higher the nonlinear order of the model, the weaker its capability to handle such rapidly varying modes, and the more demanding the requirements on the numerical scheme. This reflects a common phenomenon. (iii) Although additional viscous dissip

关键词： Supersonic flow

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numerical Simulations on Buckling Failure of Preloaded Cylindrical Shell Irradiated by High Power Laser Beam

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Journal of Beijing Institute of technology 2004年第3期13卷 236-241页

作者：王吉王肖钧王峰赵凯 Department of Mechanics and Mechanical Engineering University of Science and Technology of China Hefei Anhui230027 China .National Key Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China

With finite-element software ANSYS 7.0 and simple thermal-mechanical coupling constitutive relations,the buckling failure of preloaded cylindrical shell irradiated by high power laser beam was studied by numerical simulations. The buckling mode and buckling critical loading were analysed for different preloading conditions. The influence of laser intensity, beam irradiation time, preloading conditions and geometric parameters of cylindrical shell on the buckling mode were discussed. The numerical results show that: ① the buckling deformation of the cylindrical shell was concentrated in the area of laser spot and the radial buckling was the main buckling mode, ② a linear relationship between the buckling eigenvalue and the maximum temperature at the center of laser spot was approached, ③ the buckling failure of cylindrical shell was attributed to the coupling effect of the material softening and the radial deformation in the laser spot, and hence to raise the stiffness of the material would enhance the ability for anti-irradiation of structure substantially..

关键词： cylindrical shell buckling laser beam irradiation

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