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Controlling chaos to unstable periodic orbits and equilibrium state solutions for the coupled dynamos system

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Chinese Physics B 2010年第2期19卷 149-156页

作者：吴淑花郝建红许海波 school of Electric and Electronic engineering North China Electric Power University Department of Physics and electrical Information engineering Shijiazhuang Normal College Institute of Applied Physics and Computational Mathematics

In the case where the knowledge of goal states is not known, the controllers are constructed to stabilize unstable steady states for a coupled dynamos system. A delayed feedback control technique is used to suppress chaos to unstable focuses and unstable periodic orbits. To overcome the topological limitation that the saddle-type steady state cannot be stabilized, an adaptive control based on LaSalle＇s invariance principle is used to control chaos to unstable equilibrium （i.e. saddle point, focus, node, etc.）. The control technique does not require any computer analysis of the system dynamics, and it operates without needing to know any explicit knowledge of the desired steady-state position.

关键词： coupled dynamos system delayed feedback control adaptive control controlling chaos

Hydrodynamic characteristics and noise reduction mechanism of a wave leading hydrofoil placed in the wake of a cylinder

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Journal of Hydrodynamics 2023年第6期35卷 1089-1100页

作者： Bing Zhu Yue Li Wen-jun Xu Wei Zhang school of Energy and Power engineering University of Shanghai for Science and TechnologyShanghai200093China National Key Laboratory of marine Engine Science and Technology Shanghai201108China marine Design and Research Institute of China Shanghai200011China

We have investigated the hydrodynamic and acoustic performance of a hydrofoil with a wave leading edge that is being ingested in a cylindrical wake,to explore the interaction and noise reduction mechanism with the use of near flow field and far field noise decoupled prediction methods of large eddy simulation(LES)and Ffowcs Williams-Hawkings(FW-H).Our results indicate that the wave leading edge has minimal effect on the hydrodynamic performance,however,it has demonstrated the ability to significantly improve the acoustic *** the comparison of sound pressure level(SPL)and acoustic directivity,we have observed that the wave leading edge can significantly reduce the broadband noise in the far *** is due to its ability to break the large-scale structure of the incoming flow,which weakens the direct impact and therefore reduces the tone ***,the interaction between the broken vortex and the boundary layer around the hydrofoil surface is weakened,leading to a reduction in surface pressure pulsation and broadband noise *** wave structure primarily affects the flow structure near the leading edge,resulting in a reduction in flow disturbance and sound source intensity,and an improvement in the acoustic feedback loop between the foil and the fore-cylinder.

关键词： Wave leading hydrofoil cylinder wake ingesting turbulence noise reduction large eddy simulation(LES)

Malware-Propagative Mobile Ad Hoc Networks:Asymptotic Behavior Analysis

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Journal of Computer Science & Technology 2008年第3期23卷 389-399页

作者： Vasileios Karyotis Anastasios Kakalis Symeon Papavassiliou Network Management and Optimal Design Lab(NETMODE) School of Electrical and Computer Engineering National Technical University of Athens(NTUA)AthensGreece

In this paper, the spreading of malicious software over ad hoc networks, where legitimate nodes are prone to propagate the infections they receive from either an attacker or their already infected neighbors, is analyzed. Considering the Susceptible-Infected-Susceptible （SIS） node infection paradigm we propose a probabilistic model, on the basis of the theory of closed queuing networks, that aims at describing the aggregated behavior of the system when attacked by malicious nodes. Because of its nature, the model is also able to deal more effectively with the stochastic behavior of attackers and the inherent probabilistic nature of the wireless environment. The proposed model is able to describe accurately the asymptotic behavior of malware-propagative large scale ad hoc networking environments. Using the Norton equivalent of the closed queuing network, we obtain analytical results for its steady state behavior, which in turn is used for identifying the critical parameters affecting the operation of the network. Finally, through modeling and simulation, some additional numerical results are obtained with respect to the behavior of the system when multiple attackers are present, and regarding the time-dependent evolution and impact of an attack.

关键词： wireless ad hoc networks infection efficiency closed queuing networks

Optimization of dielectric constant temperature coefficient of pyrochlores containing bismuth

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中国有色金属学会会刊：英文版 2005年第2期15卷 252-256页

作者：任庆利罗强陈寿田 school of Technical Physics Xidian University Xi'an 710071 China school of electrical engineering Xi'an Jiaotong University Xi'an 710049 China The First Department The Second Artillery Institute of Engineering Xi'an 710025 China

The Bi2O3-ZnO-Nb2O5（BZN）-based ceramic samples were prepared according to the optimum composition of (Bi3xZn2-3x)(ZnxNb2-x)O7 by solid state reaction. The BZN ceramic structure and the dielectric properties were explored via X-ray diffractometer（XRD）, differential thermal analysis（DTA）, scanning electron microscope（SEM）, and HP4275A impedance analysis. The amphoteric surface active agent with alcohol amine double nature is introduced when the raw materials are mixed and ground. The anatase titania doped BZN-based ceramics was also investigated. Either doping the anatase TiO2 or adding the surface active agent or both of them can widen sintering temperature range which satisfies the zero temperature coefficient (0±30×10-6/℃) of the BZN ceramics. And these BZN ceramics with diphasic pyrochlore structure possess excellent dielectric properties.

关键词：相转换三氧化二铋氧化锌五氧化二铌绝缘陶瓷

Photothermal hygroscopic hydrogel for simultaneous generation of clean water and electricity

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Science China(Technological Sciences) 2023年第10期66卷 2958-2967页

作者： REN TingTing HUANG Lu XIE ShangZhen CHEN GuoPeng LIU Peng CHEN LinGen Institute of Thermal Science and Power engineering Wuhan Institute of TechnologyWuhan 430205China school of Mechanical&electrical engineering Wuhan Institute of TechnologyWuhan 430205China

Harvesting water from the air using adsorbents and obtaining fresh water by solar-driven desorption is considered as one of the most effective ways to solve the freshwater crisis in arid and desert *** on a simple and low-cost photothermal hygroscopic hydrogel,a new strategy is proposed to boost solar energy efficiency by coupling solar-driven atmospheric water harvesting technology with thermoelectric power generation technology in this *** hygroscopic hydrogel ink PAM-CaCl_(2)is prepared by in situ polymerization using Acrylamide as monomer,Ammonium persulfate as thermal initiator and CaCl_(2)as hygroscopic *** the day,the photothermal hygroscopic hydrogel absorbs solar energy and evaporates its own internal water to obtain fresh ***,the residual waste heat is utilized to power the thermoelectric panel,which produces electricity based on Seebeck *** night,the hydrogel harvests water molecules in the air to achieve *** hybrid system can achieve a water production rate of 0.33 kg m^(-2)h^(-1)and an additional electrical energy gain of 124 mW m^(-2)at 1 kW m^(-2)solar *** model of the hybrid system is developed to understand the heat flow and thermoelectric generation *** results provide new insights into energy and freshwater replenishment options in arid or desert areas with abundant solar energy.

关键词： photothermal hygroscopic hydrogel atmospheric water harvesting solar steam generation thermoelectric power generation

Corrections of Original CFPREV Control in LCC-HVDC Links and Analysis of Its Inherent Plateau Effect

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CSEE Journal of Power and Energy Systems 2022年第1期8卷 10-16页

作者： Dachuan Tian Xiaofu Xiong College of Automation Chongqing University of Posts and TelecommunicationsChongqing 400065China school of electrical engineering Chongqing UniversityChongqing 400044China

The most effective approach to suppressing the first commutation failure(CF)of the LCC-HVDC link at fault inception is to advance firings of the inverter,and the commutation failure prevention(CFPREV)control is the most commonly used method in practical ***,it is discovered in this study that there exist a few serious defects in its original scheme,and thus targeted vital corrections were ***,an interesting phenomenon termed the plateau effect,which states that an excessive advancement of firings will contrarily and inevitably lead to more commutation failures,is also revealed and *** turns out that the inherent commutation dents of the Graetz bridge should be primarily responsible,which bridges the knowledge gap and further enhances the cognition of the limitation of CFPREV control,and it may also be conducive to the design of related control *** results then validate the necessity of these presented corrections and confirm the existence of the plateau effect.

关键词： Commutation failure CFPREV LCC-HVDC transmission plateau effect

Measurement of out-of-plane deformation of curved objects with digital speckle pattern interferometry

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Chinese Optics Letters 2018年第11期16卷 40-46页

作者： Pengfei Li Ping Cai Jun Long Chiyue Liu Hao Yan Department of Instrument School of Electronic Information and Electrical EngineeringShanghai Jiao Tong UniversityShanghai 200240China Corresponding author：pcai@***

Digital speckle pattern interferometry （DSPI） is a high-precision deformation t technique for planar objects. However, for curved objects, the three-dimensional （3D） shape information is needed in order to obtain correct deformation measurement in DSPI. Thus, combined shape and deformation measurement techniques of DSPI have been proposed. However, the current techniques are either complex in setup or complicated in operation. Furthermore, the operations of some techniques are too slow for real-time measurement. In this work, we propose a DSPI technique for both 3D shape and out-of-plane deformation measurement. Compared with current techniques, the proposed technique is simple in both setup and operation and is capable of fast deformation measurement. Theoretical analysis and experiments are performed. For a cylinder surface with an arch height of 9 mm, the error of out-of-plane deformation measurement is less than 0.15 μm. The effectiveness of the proposed scheme is verified.

关键词： Measurement of out-of-plane deformation of curved objects with digital speckle pattern interferometry

Three-phase flow of submarine gas hydrate pipe transport

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Journal of Central South University 2015年第9期22卷 3650-3656页

作者：李立徐海良杨放琼 State Key Laboratory of High Performance and Complex Manufacturing (Central South University) school of Mechanical and electrical engineering Central South University

In the hydraulic transporting process of cutter-suction mining natural gas hydrate, when the temperature-pressure equilibrium of gas hydrate is broken, gas hydrates dissociate into gas. As a result, solid-liquid two-phase flow(hydrate and water) transforms into gas-solid-liquid three-phase flow(methane, hydrate and water) inside the pipeline. The Euler model and CFD-PBM model were used to simulate gas-solid-liquid three-phase flow. Numerical simulation results show that the gas and solid phase gradually accumulate to the center of the pipe. Flow velocity decreases from center to boundary of the pipe along the radial direction. Comparison of numerical simulation results of two models reveals that the flow state simulated by CFD-PBM model is more uniform than that simulated by Euler model, and the main behavior of the bubble is small bubbles coalescence to large one. Comparison of numerical simulation and experimental investigation shows that the values of flow velocity and gas fraction in CFD-PBM model agree with experimental data better than those in Euler model. The proposed PBM model provides a more accurate and effective way to estimate three-phase flow state of transporting gas hydrate within the submarine pipeline.

关键词： gas hydrate pipe transport three-phase flow Euler model CFD-PBM model

Component Content Soft-sensor Based on Neural Networks in Rare-earth Countercurrent Extraction Process

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自动化学报 2006年第4期32卷 489-495页

作者： YANG Hui CHAI Tian-You school of Electronics and electrical engineering East China Jiaotong University Nanchang 330013 Research Center of Automation Northeastern University Shenyang 110004

Throught fusion of the mechanism modeling and the neural networks modeling,a compo- nent content soft-sensor,which is composed of the equilibrium calculation model for multi-component rare earth extraction and the error compensation model of fuzzy system,is proposed to solve the prob- lem that the component content in countercurrent rare-earth extraction process is hardly measured *** industry experiment in the extraction Y process by HAB using this hybrid soft-sensor proves its effectiveness.

关键词： Rare-earth countercurrent extraction soft-sensor equilibrium calculation model neural networks