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Time delay and cross-correlated Gaussian noises-induced stochastic stability and regime shift between steady states for an insect outbreak system

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International Journal of Biomathematics 2019年第4期12卷 301-323页

作者： kang-kang wang Ya-Jun wang Hui Ye Sheng-Hong Li School of Science Jiangsu University of Science and Technology Zhenjiang 212003 P. R. China Center of Complex Systems and Network Science Research Southeast University Nanjing 210096 P. R. China School of Mathematical Sciences Nanjing Normal University Nanjing 210097 P. R. China

In this paper, we focus on investigating the stochastic stability and the regime transition between the endangered state and the boom state for a time-delayed insect growth system driven by correlated external and internal noises. By use of the Fokker Planck equation, the method of small time delay approximation and the fast descent method, we explore in detail the joint action of noise terms and time delay on the mean reproduction and depression time for the insect population. Our investigations indicate that the pseudo-resonance phenomenon of the mean first-passage time (MFPT) occurs because of the impact of different noises and time delay. Through the numerical calculation, it is discovered that multiplicative noise can speed up the shift of the insect population from the boom state to the endangered one, while the noise correlation and time delay can propel the insect system to evolve from the endangered state to the boom state and improve the biological stability. In addition, the impact of the additive noise on the stability of the biological system depends on the positive and negative situation of the noise correlation. On the other hand, during the process of suppressing the insect explosion, it is beneficial to the pest control to amplify the association noise strength and weaken the intensities of the multiplicative, additive noises and time delay. However, during the process of eliminating the pests, it can produce nice effect on the disinsection to increase time delay, the intensities of multiplicative and additive noises and weaken the strength of noise correlation.

关键词： Insect outbreak model correlated noises time delay mean reproduction time mean depression time

Gradient Descent Algorithm for Small UAV Parameter Estimation System

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第6期34卷 680-687页

作者： Guo Jiandong Liu Qingwen wang kang Key Laboratory of Unmanned Aerial Vehicle Technology of the Ministry of Industry and Information Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China College of Automation Engineering Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China

A gradient descent algorithm with adjustable parameter for attitude estimation is developed,aiming at the attitude measurement for small unmanned aerial vehicle(UAV)in real-time flight *** accelerometer and magnetometer are introduced to construct an error equation with the gyros,thus the drifting characteristics of gyroscope can be compensated by solving the error equation utilized by the gradient descent *** of the presented algorithm is evaluated using a self-proposed micro-electro-mechanical system(MEMS)based attitude heading reference system which is mounted on a tri-axis *** on-ground,turntable and flight experiments indicate that the estimation attitude has a good ***,the presented system is compared with an open-source flight control system which runs extended Kalman filter(EKF),and the results show that the attitude control system using the gradient descent method can estimate the attitudes for UAV effectively.

关键词： gradient descent algorithm attitude estimation quaternions small unmanned aerial vehicle(UAV)

Security Analysis of a Block Encryption Algorithm Based on Dynamic Sequences of Multiple Chaotic Systems

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Chinese Physics Letters 2011年第1期28卷 39-42页

作者： DU Mao-kang HE Bo wang Yong Key Laboratory of Electronic Commerce and Logistics Chongqing University of Posts and Telecommunications Chongqing 400065

Recently, the cryptosystem based on chaos has attracted much attention. wang and Yu （Commun. Nonlin. Sci. Numer. Simulat. 14（2009）574） proposed a block encryption algorithm based on dynamic sequences of multiple chaotic systems. We analyze the potential flaws in the algorithm. Then, a chosen-plaintext attack is presented. Some remedial measures are suggested to avoid the flaws effectively. Furthermore, an improved encryption algorithm is proposed to resist the attacks＂ and to keep all the merits of the original cryptosystem.

关键词： Computational physics Quantum information and quantum mechanics Statistical physics and nonlinear systems

Experimental study of the mechanism of nanofluid in enhancing the oil recovery in low permeability reservoirs using microfluidics

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Petroleum Science 2023年第1期20卷 382-395页

作者： kang wang Qing You Qiu-Ming Long Biao Zhou Pan wang School of Energy Resources China University of GeosciencesBeijing100083China School of Petroleum Engineering China University of PetroleumQingdao266580ShandongChina Chengdu Natural Gas Chemical General Factory Chengdu610213SichuanChina

Due to the low porosity and low permeability in unconventional reservoirs,a large amount of crude oil is trapped in micro-to nano-sized pores and throats,which leads to low oil *** have great potential to enhance oil recovery(EOR)in low permeability *** this work,the regulating ability of a nanofluid at the oil/water/solid three-phase interface was *** results indicated that the nanofluid reduced the oil/water interfacial tension by two orders of magnitude,and the expansion modulus of oil/water interface was increased by 77% at *** addition,the solid surface roughness was reduced by 50%,and the three-phase contact angle dropped from 135(oil-wet)to 48(water-wet).Combining the displacement experiments using a 2.5D reservoir micromodel and a microchannel model,the remaining oil mobilization and migration processes in micro-to nano-scale pores and throats were *** was found that the nanofluid dispersed the remaining oil into small oil droplets and displaced them via multiple mechanisms in porous ***,the high strength interface film formed by the nanofluid inhibited the coalescence of oil droplets and improved the flowing *** results help to understand the EOR mechanisms of nanofluids in low permeability reservoirs from a visual perspective.

关键词： Nanofluid EOR mechanism Micromodel Low permeability Three-phase interface

Application of non-equilibrium dendrite growth model considering thermo-kinetic correlation in twin-roll casting

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Journal of Materials Science & Technology 2020年第9期44卷 209-222页

作者： Yubing Zhang Jinglian Du kang wang Huiyuan wang Shu Li Feng Liu State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an710072China Key Laboratory of Automobile Materials of Ministry of Education and Department of Materials Science and Engineering Jilin UniversityChangchun130025China School of Science Harbin University of Science and TechnologyHarbin150080China Analytical&Testing Center Northwestern Polytechnical UniversityXi’an710072China

Upon non-equilibrium solidifications, dendrite growth, generally as precursor of as-solidified structures,has severe effects on subsequent phase transformations. Considering synergy of thermodynamics and kinetics controlling interface migration and following conservation of heat flux in solid temperature field, a more flexible modeling for the dendrite growth is herein developed for multi-component alloys,where, two inherent problems, i.e. correlation between thermodynamics and kinetics(i.e. the thermokinetic correlation), and theoretical connection between dendrite growth model and practical processing,have been successfully solved. Accordingly, both the thermodynamic driving force G and the effective kinetic energy barrier Qeffhave been found to control quantitatively the dendrite growth(i.e. especially the growth velocity, V), as reflected by the thermo-kinetic trade-off. Compared with previous models, it is the thermo-kinetic correlation that guarantees quantitative connection between the practical processing parameters and the current theoretical framework, as well as more reasonable description for kinetic behaviors involved. Applied to the vertical twin-roll casting(VTC), the present model, realizes a good prediction for kissing points, which influences significantly alloy design and processing *** work deduces quantitatively the thermo-kinetic correlation controlling the dendrite growth, and by proposing the parameter-triplets(i.e. G-Qeff-V), further opens a new beginning for connecting solidification theories with industrial applications, such as the VTC.

关键词： Dendrite growth Multi-component alloys Thermo-kinetic correlation Vertical twin-roll casting

An algorithm for decomposing a polynomial system into normal ascending sets

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Science China Mathematics 2007年第10期50卷 1441-1450页

作者： Ding-kang wang Yan ZHANG Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China Key Laboratory of Mathematics Mechanization Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing 100080 China

We present an algorithm to decompose a polynomial system into a finite set of normal ascending sets such that the set of the zeros of the polynomial system is the union of the sets of the regular zeros of the normal ascending sets. If the polynomial system is zero dimensional, the set of the zeros of the polynomials is the union of the sets of the zeros of the normal ascending sets.

关键词： zero decomposition, normal ascending set, polynomial system

All-inorganic perovskite nanocrystal materials: new generation of scintillators for high quality X-ray imaging

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Science Bulletin 2019年第17期64卷 1205-1206页

作者： kang wang Hao Zhang Zhanjun Gu Aerospace Institute of Advanced Materials & Processing Technology Beijing 100074 China bCAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety Institute of High Energy Physics and National Center for Nanoscience and Technology o f China Chinese Academy of Sciences Beijing 100049 China

Scintillating materials, which can convert high energy X-ray radiation into visible luminescence [1], are crucial parts of Xray imaging technology. Since the discovery of X-ray in 1895, scintillating materials have witnessed wild applications in various fields, including security inspection, space exploration, nondestructive detection, and medical diagnostics [2,3]- Conventional scintillators are generally large inorganic crystals and can only be grown at high temperature, which significantly increases the manufacturing difficulty and cost. The luminescence of current crystal scintillators is usually limited by lowefficiency or afterglow effects, and is difficult to be tuned cross the visible spectrum. As traditional scintillators have reached their performance limits, exploration of new scintillators has become a crucial topic considering the increased demands of X-ray imaging and detection technology [4-6].

关键词： space exploration visible spectrum high energy

CCM3 and cerebral cavernous malformation disease

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Stroke & Vascular Neurology 2019年第2期4卷 67-70页

作者： kang wang Huanjiao Jenny Zhou Min wang Interdepartmental Program in Vascular Biology and Therapeutics Department of PathologyYale University School of MedicineNew HavenConnecticutUSA

Cerebral cavernous malformations(CCMs)are vascular lesions characterised by enlarged and irregular structure of small blood vessels in the brain,which can result in increased risk of stroke,focal neurological defects and *** different genes,CCM1/Krev/Rap1 Interacting Trapped 1,CCM2/MGC4607 and CCM3/PDCD10,are associated with the CCMs’progression,and mutations in one of three CCM genes cause CCM *** three CCM proteins have similar function in maintaining the normal structure of small blood ***,CCM3 mutation results in a more severe form of the disease which may suggest that CCM3 has unique biological function in the *** current review focuses on the signalling pathways mediated by CCM3 in regulating endothelial cell junction,proliferation,migration and *** findings may offer potential therapeutic strategies for the treatment of CCMs.

关键词： cerebral malformation finding

On abundant wave structures of the unsteady korteweg-de vries equation arising in shallow water

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Journal of Ocean Engineering and Science 2023年第6期8卷 595-601页

作者： kang-jia wang Jing-Hua Liu School of Physics and Electronic Information Engineering Henan Polytechnic UniversityJiaozuo 454003China

The aim of this paper is to study the unsteady korteweg-de vries equation that plays an important role in describing the shallow *** analytical techniques namely the Sardar-subequation method and the energy balance method are employed to seek the abundant traveling wave solutions for the first *** these two methods,plenty of traveling wave solutions such as the bright solitary wave solutions,dark solitary wave solutions,singular periodic wave solutions and perfect periodic wave solution that expressed in terms of the generalized hyperbolic functions,generalized trigonometric functions and the cosine function are ***,the dynamic behaviors of the solutions are described through the 3D plot and 2D *** results in this paper demonstrate that the proposed methods are powerful and effective to construct the traveling wave solutions of the nonlinear evolution equations in ocean engineering and science.

关键词： Sardar-subequation method Energy balance method Unsteady korteweg-de vries equation Solitary wave solution Periodic wave solution