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Singularities of the Curve Shortening Flow in a Riemannian Manifold

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Acta Mathematica Sinica,English Series 2021年第11期37卷 1783-1793页

作者： Shu Jing pan School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026P.R.China

In this paper,the curve shortening flow in a general Riemannian manifold is studied,Altschuler’s results about the flow for space curves are *** any n-dimensional(n ≥ 2)Riemannian manifold(M,g) with some natural ass... 详细信息

关键词： Curve shortening flow blow-up singularity formation

Shape optimisation of basin insulator for DC gas insulated switchgear/gas insulated transmission lines based on artificial bee colony algorithm

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High Voltage 2024年第2期9卷 275-286页

作者： Yi Luo Shiyi Mao Ju Tang Zijun pan Cheng pan State Key Laboratory of Power Grid Environmental Protection School of Electrical Engineering and AutomationWuhan UniversityWuhanChina

The surface charge accumulation on the basin insulator is a particular problem in high-voltage direct current(HVDC)gas insulated switchgears(GIS)and gas insulated trans-mission lines(GIL),which restricts the development and application of extra/ultra high-voltage(EHV/UHV)*** surface charge distribution and anti-flashover performance are closely related to the insulator *** obtain the optimal basin insulator,a shape optimisation model based on artificial bee colony algorithm was established,and the minimisation objective functions based on capacitive(initial)electric field distribution and resistive(steady-state)electric field distribution were respectively *** optimisation results of the two objective functions were calculated,and the electric field and charge distribution on the surface of the insulator before and after optimisation were evaluated and compared using the simulation *** results indicated that the optimisation based on the capacitive electric field can significantly inhibit the surface charge accumulation,and the optimised insulator can significantly reduce the surface normal electric field and make the distribution of the tangential electric field more uniform,and the maximum tangential electric field can be reduced by 10%;the optimisation based on resistive electric field can achieve similar results,but requires more computational *** on the results,the‘anti-charge’basin insulator structure suitable for the DC field was given.

关键词： insulator artificial charge

Characteristics of river discharge and its indirect effect on the tidal bore in the Qiantang River, China

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International Journal of Sediment Research 2023年第2期38卷 253-264页

作者： Cunhong pan Qiushun Wang Dongzi pan Chengfei Hu Zhejiang Institute of Hydraulics and Estuary Zhejiang Provincial Key Laboratory of Estuary and Coast

Based on field data of river discharge, tide, tidal bore, and riverbed topography, the characteristics of river discharge, the effect of river discharge on riverbed erosion and sedimentation, and the feedback effect of riverbed erosion and sedimentation on the tide and tidal bore in the Qiantang River are analyzed. The results show that the inter-annual and seasonal variation of river discharge in the Qiantang River is noticeable, while the seasonal distribution of river discharge tends to be uniform after the construction of Xin’anjiang Reservoir. River discharge has a major effect on the erosion and sedimentation in the reach from Zhakou to Yanguan. There are laws of riverbed erosion in wet seasons and years and sedimentation in dry seasons and years. Relations in the Zhakou to Yanguan reach among the riverbed volume after the flood season, the mean and maximum river discharge during the flood season, and riverbed volume before the flood season are established. With the riverbed erosion from Zhakou to Yanguan, the low tide level decreases and the tidal range is amplified, and thus, the tidal bore is enhanced. The relation among tidal range, river discharge, and riverbed volume, as well as the one between the tidal bore height and tidal range is established on the basis of the field data. Furthermore, the variation range of tidal bores after the flood season is analyzed in wet and dry years. The indirect effect of the Xin’anjiang Reservoir on the height of the tidal bore is predicted and the mean height of the tidal bore from Zhakou to Yanguan decreases by 0.1-0.2 m.

关键词： Qiantang River Tidal bore Tide River discharge Riverbed erosion Riverbed sedimentation

Test and simulation of full-scale self-centering beam-to-column connection

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Earthquake Engineering and Engineering Vibration 2013年第4期12卷 599-607页

作者： Deng Kailai pan Peng Alexandre Lam pan Zhenhua Ye Lieping Key Laboratory of Civil Engineering Safety and Durability of China Education Ministry Department of Civil EngineeringTsinghua University

A new type of beam-to-column connection for steel moment flames, designated as a ＂self-centering connection,＂ is studied. In this connection, bolted top-and-seat angles, and post-tensioned （PT） high-strength steel strands running along the beam are used. The PT strands tie the beam flanges on the column flange to resist moment and provide self-centering force. After an earthquake, the connections have zero deformation, and can be restored to their original status by simply replacing the angles. Four full-scale connections were tested under cyclic loading. The strength, energy-dissipation capacity, hysteresis curve, as well as angles and PT strands behavior of the connections are investigated. A general FEM analysis program called ABAQUS 6.9 is adopted to model the four test specimens. The numerical and test results match very well. Both the test and analysis results suggest that：（1） the columns and beams remain elastic while the angles sustain plastic deformations for energy dissipation when the rotation of the beam related to the column equals 0.05 tad, （2） the energy dissipation capacity is enhanced when the thickness of the angle is increased, and （3） the number of PT strands has a significant influence on the behavior of the connections, whereas the distance between the strands is not as important to the performance of the connection.

关键词： steel frame connection angle post-tensioned prestressing self-centering

Perovskite sensitized 2D photodiodes

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Light(Science & Applications) 2023年第6期12卷 951-952页

作者： Dong Li Anlian pan Key Laboratory for Micro-Nano Physics and Technology of Hunan Province State Key Laboratory of Chemo/Biosensing and ChemometricsHunan Institute of Optoelectronic IntegrationCollege of Materials Science and EngineeringHunan UniversityChangshaChina

A new type of perovskite sensitized programmable WSe_(2) photodiode is constructed based on MAPbI_(3)/WSe_(2) heterojunction,presenting flexible reconfigurable characteristics and prominent optoelectronic performances.

关键词： heterojunction optoelectronic reconfigurable

Fixed point behavior of cumulants in the three-dimensional Ising universality class

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Chinese Physics C 2022年第2期46卷 112-121页

作者： Xue pan School of Electronic Engineering Chengdu Technological UniversityChengdu 611730China

High-order cumulants and factorial cumulants of conserved charges are suggested for the study of the critical dynamics in heavy-ion collision experiments. In this paper, using the parametric representation of the threedimensional Ising model which is believed to belong to the same universality class as quantum chromo-dynamics,the temperature dependence of the second-to fourth-order(factorial) cumulants of the order parameter is studied. It is found that the values of the normalized cumulants are independent of the external magnetic field at the critical temperature, which results in a fixed point in the temperature dependence of the normalized cumulants. In finite-size systems simulated using the Monte Carlo method, this fixed point behavior still exists at temperatures near the critical. This fixed point behavior has also appeared in the temperature dependence of normalized factorial cumulants from at least the fourth order. With a mapping from the Ising model to QCD, the fixed point behavior is also found in the energy dependence of the normalized cumulants(or fourth-order factorial cumulants) along different freezeout curves.

关键词： cumulants factorial cumulants fixed point Ising universality class

New approach for improving throughput in multi-channel packet radio systems

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Journal of Systems Engineering and Electronics 2010年第2期21卷 180-185页

作者： Su pan Shengmei Liu College of Telecommunications and Information Engineering Nanjing University of Posts and Telecommunications Nanjing 210003 P. R. China

A new approach for improving the throughputs of multi- channel packet radio systems is proposed. Based on the charac- teristics of multi-code CDMA technology, the scheme factitiously improves the transmission bit rate of a terminal by compressing the packet transmission time and thereby increases the number of the orthogonal spreading codes used by the terminal. By this means, the average interference level of the system is reduced and the system capacity is improved. Simulation results show that the proposed scheme exhibits larger throughput compared with the traditional multi-code CDMA slotted Aloha systems.

关键词： packet radio multi-channel throughput MAC

Investigation on the Pinch Point Position in Heat Exchangers

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Journal of Thermal Science 2016年第3期25卷 258-265页

作者： pan Lisheng SHI Weixiu State Key Laboratory of High-temperature Gas Dynamics Institute of MechanicsChinese Academy of Sciences School of Environment and Energy Engineering Beijing University of Civil Engineering and Architecture

The pinch point is important for analyzing heat transfer in thermodynamic cycles. With the aim to reveal the importance of determining the accurate pinch point, the research on the pinch point position is carried out by theoretical method. The results show that the pinch point position depends on the parameters of the heat transfer fluids and the major fluid properties. In most cases, the pinch point locates at the bubble point for the evaporator and the dew point for the condenser. However, the pinch point shills to the supercooled liquid state in the near critical conditions for the evaporator. Similarly, it shifts to the superheated vapor state with the condensing temperature approaching the critical temperature for the condenser. It even can shift to the working fluid entrance of the evaporator or the supereritical heater when the heat source fluid temperature is very high compared with the absorb- ing heat temperature. A wrong position for the pinch point may generate serious mistake. In brief, the pinch point should be founded by the itcrativc method in all conditions rather than taking for granted.

关键词： pinch point position heat exchanger heat transfer phase transition supercritical condition

Fundamental theories and basic principles of triboelectric effect: A review

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Friction 2019年第1期7卷 2-17页

作者： Shuaihang pan Zhinan ZHANG School of Mechanical Engineering Shanghai Jiao Tong University School of Mechanical & Aerospace Engineering University of California Los Angeles

Long-term observation of the triboelectric effect has not only proved the feasibility of many novel and useful tribo-devices(e.g., triboelectric nanogenerators), but also constantly motivated the exploration of its mysterious nature. In the pursuit of a comprehensive understanding of how the triboelectric process works, a more accurate description of the triboelectric effect and its related parameters and factors is urgently required. This review critically goes through the fundamental theories and basic principles governing the triboelectric process. By investigating the difference between each charging media, the electron, ion, and material transfer is discussed and the theoretical deduction in the past decades is provided. With the information from the triboelectric series, interesting phenomena including cyclic triboelectric sequence and asymmetric triboelectrification are precisely analyzed. Then, the interaction between the tribo-system and its operational environment is analyzed, and a fundamental description of its effects on the triboelectric process and results is summarized. In brief, this review is expected to provide a strong understanding of the triboelectric effect in a more rigorous mathematical and physical sense.

关键词： triboelectric effect triboelectrification triboelectric nanogenerators(TENGs) interface