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effects of fluid recirculation on mass transfer from the arterial surface to flowing blood

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Acta Mechanica Sinica 2012年第3期28卷 904-910页

作者： Zhi-Guo zhang xi-Wen zhang Ying-xi Liu Department of engineering Mechanics Faculty of Vehicle Engineering and MechanicsState Key Laboratory of Structural Analysisfor Industrial EquipmentDalian University of Technology116024 DalianChina School of Aerospace Tsinghua University100084 BeijingChina

The effect of disturbed flow on the mass trans- fer from arterial surface to flowing blood was studied nu- merically, and the results were compared with that of our previous work. The arterial wall was assumed to be vis- coelastic and the blood was assumed to be incompressible and non-Newtonian fluid, which is more close to human arte- rial system. Numerical results indicated that the mass trans- fer from the arterial surface to flowing blood in regions of disturbed flow is positively related with the wall shear rates and it is significantly enhanced in regions of disturbed flow with a local minimum around the reattachment point which is higher than the average value of the downstream. There- fore, it may be implied that the accumulation of cholesterol or lipids within atheromatous plaques is not caused by the reduced efflux of cholesterol or lipids, but by the infiltration of the LDL （low-density lipoprotein） from the flowing blood to the arterial wall.

关键词： Disturbed flow Arterial wall Mass transfer Atherosclerosis Wall shear rates

Strategic integration of 2D perovskite and chiral quantum dot hybrid heterostructures for superior CPL detection

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Science China Technological Sciences 2025年第1期 368-377页

作者： Jiahe YAN xi zhang Lei LIU Hualin BI Mengke WANG Jing LI Jun WANG Department of Chemistry College of SciencesNortheastern University Technical Institute of Physics and Chemistry Chinese Academy of Sciences

Circularly polarized light（CPL） detection has garnered significant research interest due to its extensive applications in optoelectronics and quantum *** perovskites possess CPL detection capabilities due to their inherent ***,incorporating organic amine spacers distorts the crystal lattice,resulting in defects that reduce the sensitivity of CPL *** study introduces the concept of chiral superposition for the first time,reporting two mixed heterostructures composed of two-dimensional（2D） chiral perovskite（R/S-MBA）2MAPb2I7（R/S）,chiral quantum dots（R/S-MBA）-CsPbBr3（R/SQD）,and chiral carbon dots（Ch-CDs）.The addition of chiral quantum dots/Ch-CDs fills the defects of the chiral perovskite films and reduces the electron-hole recombination rate in chiral hybrid perovskites,thereby significantly enhancing the circularly polarized sensitivity of the CPL *** adjusting the concentration of chiral quantum dots,controllability of spin electron transfer is achieved,which has a notable impact on circular dichroism（CD） and anisotropy factor *** anisotropy factor glhpof the mixed heterostructure R/S-R/SQD is approximately 21.58 times higher than that of single-phase chiral perovskites,and the asymmetry factor gCDincreases ***,this work opens up a new effective pathway for achieving high-sensitivity CPL detection,with promising applications in optoelectronic technologies such as spin information communication and quantum optics.

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Atmospheric regimes and trends on exoplanets and brown dwarfs

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Research in Astronomy and Astrophysics 2020年第7期20卷 1-92页

作者： xi zhang Department of earth and Planetary Sciences University of California Santa CruzCA 95064USA

A planetary atmosphere is the outer gas layer of a planet. Besides its scientific significance among the first and most accessible planetary layers observed from space, it is closely connected with planetary formation and evolution, surface and interior processes, and habitability of planets. Current theories of planetary atmospheres were primarily obtained through the studies of eight large planets, Pluto and three large moons(Io, Titan, and Triton) in the Solar System. Outside the Solar System, more than four thousand extrasolar planets(exoplanets) and two thousand brown dwarfs have been confirmed in our Galaxy, and their population is rapidly growing. The rich information from these exotic bodies offers a database to test, in a statistical sense, the fundamental theories of planetary climates. Here we review the current knowledge on atmospheres of exoplanets and brown dwarfs from recent observations and theories. This review highlights important regimes and statistical trends in an ensemble of atmospheres as an initial step towards fully characterizing diverse substellar atmospheres, that illustrates the underlying principles and critical *** are obtained through analysis of the dependence of atmospheric characteristics on basic planetary parameters. Dominant processes that influence atmospheric stability, energy transport, temperature, composition and flow pattern are discussed and elaborated with simple scaling laws. We dedicate this review to Dr. Adam P. Showman(1968–2020) in recognition of his fundamental contribution to the understanding of atmospheric dynamics on giant planets, exoplanets and brown dwarfs.

关键词： planets and satellites:atmospheres planets and satellites:gaseous planets planets and satellites:terrestrial planets planets and satellites:physical evolution stars:brown dwarfs

Resilient predictive control for a class of uncertain time-delay systems

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Journal of Systems engineering and electronics 2007年第2期18卷 334-340页

作者： zhang Qunliang xi Yugeng Dept. of Automation Shanghai Jiaotong Univ. Shanghai 200240 P.R. China

In practice, gain perturbations of controllers which axe caused by actuator degradation and other reasons often lead to performance degradation. They are capable of violating the closed-loop stability. For a system with constrained inputs, the actual controllers might exceed their limits because of gain perturbations. By the reason, this article considers the problem of resilient predictive control for a class of uncertain time-delay systems. By describing the gain perturbation as a time-varying uncertainty, the sufficient conditions to ensure the closedloop stability and the input constraints are derived. Additionally, an approach to design the resilient predictive controllers is presented in terms of LMI. Finally, the simulation shows that the proposed approach is very effective.

关键词： Gain perturbations Constraints Resilient predictive controllers Stability.

Application of MLPG in large deformation analysis

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Acta Mechanica Sinica 2006年第4期22卷 331-340页

作者： xi zhang Zhenhan Yao zhangfei zhang Department of engineering Mechanics Tsinghua University Beijing 100084 China

Two-dimensional large deformation analysis of hyperelastic and elasto-plastic solids based on the Meshless Local Petrov-Galerkin method （MLPG） is presented. A material configuration based the nonlinear MLPG formulation is introduced for the large deformation analysis of both path-dependent and path-independent materials. The supports of the MLS approximation functions cover the same sets of nodes during material deformation, thus the shape function needs to be computed only in the initial stage. The multiplicative hyperelasto-plastic constitutive model is adopted to avoid objective time integration for stress update in large rota- tion. With this constitutive model, the computational formulations for path-dependent and path-independent materials become identical. Computational efficiency of the nonlinear MLPG method is discussed and optimized in several aspects to make the MLPG an O（N） algorithm. The numerical examples indicate that the MLPG method can solve large deformation problems accurately. Moreover, the MLPG computations enjoy better convergence rate than the FeM under very large particle distortion.

关键词： Meshless method MLPG. Large deformation Hyperelasticity Hyperelasto-plasticity

A Study on the Technique of Observing Interplanetary Scintillation with Simultaneous Dual-Frequency Measurements

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 712-720页

作者： xi-Zhen zhang National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

Ground-based observation of Interplanetary Scintillation （IPS） is an important approach of monitoring solar wind speed. We describe both the principle and method of observing the solar wind speed by using the normalized cross-spectrum of simultaneous dualfrequency IPS measurement. The effects of the solar wind properties and the angular size of the scintillation source on the measurement of solar wind speed are investigated by numerical analysis. We carry out a comparison of this method with the traditional single station-single frequency method. We outline a new IPS observation system using this method now under construction at the National Astronomical Observatories, CAS （NAOC）.

关键词： interplanetary scintillation -- method -- instrument -- telescope

The limiting behaviour of the Hermitian-Yang-Mills flow over compact non-Kahler manifolds

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Science China Mathematics 2020年第7期63卷 1369-1390页

作者： Yanci Nie xi zhang School of Mathematical Sciences Xiamen UniversityXiamen 361005China School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China

In this paper,we analyze the asymptotic behaviour of the Hermitian-Yang-Mills flow over a compact non-Kahler manifold(X,g)with the Hermitian metric g satisfying the Gauduchon and Astheno-Kahler condition.

关键词： Gauduchon Astheno-Kahler Hermitian-Yang-Mills flow

A review of the neurotransmitter system associated with cognitive function of the cerebellum in Parkinson's disease

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Neural Regeneration Research 2024年第2期19卷 324-330页

作者： xi Chen Yuhu zhang Department of Neurology Guangdong Neuroscience InstituteGuangdong Provincial People’s Hospital(Guangdong Academy of Medical Sciences)Southern Medical UniversityGuangzhouGuangdong ProvinceChina Shantou University Medical College ShantouGuangdong ProvinceChina

The dichotomized brain system is a concept that was generalized from the‘dual syndrome hypothesis’to explain the heterogeneity of cognitive impairment,in which anterior and posterior brain systems are independent but partially *** dopaminergic system acts on the anterior brain and is responsible for executive function,working memory,and *** contrast,the cholinergic system acts on the posterior brain and is responsible for semantic fluency and visuospatial *** from dopaminergic/cholinergic imaging or functional neuroimaging has shed significant insight relating to the involvement of the cerebellum in the cognitive process of patients with Parkinson’s *** research has reported evidence that the cerebellum receives both dopaminergic and cholinergic ***,whether these two neurotransmitter systems are associated with cognitive function has yet to be fully ***,the precise role of the cerebellum in patients with Parkinson’s disease and cognitive impairment remains ***,in this review,we summarize the cerebellar dopaminergic and cholinergic projections and their relationships with cognition,as reported by previous studies,and investigated the role of the cerebellum in patients with Parkinson’s disease and cognitive impairment,as determined by functional *** findings will help us to understand the role of the cerebellum in the mechanisms underlying cognitive impairment in Parkinson’s disease.

关键词： anterior brain system cerebellum cholinergic cognitive impairment dopaminergic dual syndrome hypothesis neuroimage neurotransmitter Parkinson’s disease posterior brain system therapeutic targets

Higgs bundles over foliation manifolds

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Science China Mathematics 2021年第2期64卷 399-420页

作者： Di Wu xi zhang School of Mathematical Sciences University of Science and Technology of ChinaHefei 230026China

In this paper,we consider the stability,semi-stability and canonical metric structures on transverse Higgs bundles over a class of foliation *** a transversal Bogomolov inequality is obtained.

关键词： foliation manifold Higgs bundle (approximate)transverse Hermitian-einstein transversal Bogomolov inequality