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Parity–time symmetric photonics

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National Science Review 2018年第2期5卷 183-199页

作者： han zhao Liang Feng Department of Electrical and Systems Engineering University of Pennsylvania Department of Materials Science and Engineering University of Pennsylvania

The establishment of non-Hermitian quantum mechanics(such as parity–time(PT) symmetry) stimulates a paradigmatic shift for studying symmetries of complex potentials. Owing to the convenient manipulation of optical gain and loss in analogy to complex quantum potentials, photonics provides an ideal platform for the visualization of many conceptually striking predictions from non-Hermitian quantum theory. A rapidly developing field has emerged, namely, PT-symmetric photonics, demonstrating intriguing optical phenomena including eigenstate coalescence and spontaneous PT-symmetry breaking. The advance of quantum physics, as the feedback, provides photonics with brand-new paradigms to explore the entire complex permittivity plane for novel optical functionalities. Here, we review recent exciting breakthroughs in PT-symmetric photonics while systematically presenting their underlying principles guided by non-Hermitian symmetries. The potential device applications for optical communication and computing,biochemical sensing and healthcare are also discussed.

关键词： photonics parity–time symmetry non-Hermitian phase transition exceptional point

STABILITY EIGENFUNCTIONS OF A BOUNDARY-LAYER FLOW OVER VISCOELASTIC COMPLIANT WALL

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Journal of Hydrodynamics 2001年第4期13卷 48-54页

作者： zhao, han-Zhong Dept. of Mech. Huazhong Univ. of Sci. and Technol. Wuhan 430074 China

The eigenfunctions in a stability problem of boundary-layer flow over a viscoelastic compliant wall were studied. Two categories of modes, TSI and CIFI, exist in the eigenvalue solutions. The eigenfunctions of flow-based TSI were investigated together with those in the flow over rigid wall, whereas the eigenfunctions of wall-based CIFI were compared with the wall functions in an individual wall without fluid constraint. The physical characteristics of the eigenmodes were discussed based on their eigenfunctions.

关键词： Eigenvalues and eigenfunctions Naval vessels Stability Viscoelasticity

New Cnoidal and Solitary Wave Solutions of Coupled Higher-Order Nonlinear SchrSdinger System in Nonlinear Optics

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Communications in Theoretical Physics 2007年第1期47卷 10-14页

作者： han zhao-Xiu Collage of Statistics and Computing Science ZhejizLng Gongshagng University HzLngzhou 310018 China

The coupled higher-order nonlinear Schroedinger system is a major subject in nonlinear optics as one of the nonlinear partial differential equation which describes the propagation of optical pulses in optic fibers. By using coupled amplitude-phase formulation, a series of new exact cnoidal and solitary wave solutions with different parameters are obtained, which may have potential application in optical communication.

关键词： coupled higher-order nonlinear SchrSdinger system Jacobi elliptic function solitary wave

MULTI-AGENT AGGREGATION BEHAVIOR ANALYSIS: THE DYNAMIC COMMUNICATION TOPOLOGY

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Journal of Systems Science & Complexity 2008年第2期21卷 209-216页

作者： Sheng CHEN Lindu zhao Ying han Institute of Systems Engineering Southeast University Nanjing 210018 China

The authors extend the Gazi＇s swarm model with local neighbor rules and the dynamic communication topology, and study its aggregation properties. Results of analysis show that all agents in the models aggregate and eventually form a cohesive cluster of finite size around the swarm center or the appointed point. Finally, simulations are provided to testify some of the results. Models in the paper are more applicable to the reality for the advantage that each agent only needs the partial information of the entire dynamic system when making motion decision.

关键词： Aggregation behavior dynamic communication topology local neighbor rules multi-agent system.

ZP2:the precision regulator of egg coat architecture during fertilization

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Science China(Life Sciences) 2024年第8期67卷 1779-1780页

作者： Yi Dong Shigang zhao han zhao State Key Laboratory of Reproductive Medicine and Offspring Health Center for Reproductive MedicineInstitute of WomenChildren and Reproductive HealthShandong UniversityJinan 250012China

In a recent study published in Cell,(Nishio et al.,2024)elucidated the molecular regulatory mechanism through which organisms prevent *** process intricately involves conformational changes in the zona pellucida(ZP)*** authors present a fascinating mechanism whereby post-fertilization cleavage of the ZP subunit ZP2 triggers its oligomerization,leading to crosslinking of filaments to harden the egg coat and prevent *** also systematically analyzed the pattern of ZP filament assembly,which revealed that two protofilaments comprising type I(ZP3)and type II(ZP1/ZP2/ZP4)components interlock to form a left-handed double helix *** findings are immensely beneficial for understanding the specific role of the egg coat,providing a plethora of insights.

关键词： mechanism finding crosslinking

Efficiency of Different Methods for dsRNA Delivery in Cotton Bollworm(Helicoverpa armigera)

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Journal of Integrative Agriculture 2014年第1期13卷 115-123页

作者： YANG Jing han zhao-jun Key Laboratory of Integrated Management of Crop Diseases and Pests Ministry of Education/College of Plant ProtectionNanjing Agricultural University

RNAi trigged by dsRNA not only facilitates the development of molecular biology, but also initiates a new way for pest control by silence of fatal genes. However, one of the key limitations in pest control is lack of the convenient and efficient method for dsRNA delivery. In this study, different dsRNA delivery methods at their own optimum conditions were evaluated comparatively for their efficiency with Helicoverpa armigera as test animal. It was found that the popular one- time injection of larvae with dsRNA could reduce the pupation rate by 43.0% and enhance larva mortality by 11.7%. One- time ingestion of dsRNA did not result in any significant effect on phenotype. Continuous ingestion of in vitro synthesized dsRNA by refreshing the bait diet every day caused 40.4% decrease in successful pupation and 10.0% increase in larval mortality, which was similar as one-time injection. The most efficient method was found to be the continuous ingestion of the bacteria containing dsRNA expressed, which reduced the rate of pupation by 68.7% and enhanced the larval mortality by 34.1%. Further analysis found that dsRNA was degraded faster in midgut juice than in hemolymph. However, the cell of bacteria could protect dsRNA and delay the degradation in the midgut juice of H. armigera. These results throw light on the application of dsRNA in pest management with proper ways.

关键词： Helicoverpa armigera dsRNA delivery methods RNAi effect pest control

Dynamic Modeling and Simulation of Multi-body Systems Using the Udwadia-Kalaba Theory

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Chinese Journal of Mechanical Engineering 2013年第5期26卷 839-850页

作者： zhao han ZHEN Shengchao CHEN Ye-Hwa School of Mechanical Engineering Hefei University of Technology School of Mechanical Engineering Georgia Institute of Technology

Laboratory experiments were conducted for falling U-chain,but explicit analytic form of the general equations of motion was not *** modeling methods were developed for fish robots,however they just focused on the whole fish’s locomotion which does little favor to understand the detailed swimming behavior of ***-Kalaba theory is used to model these two multi-body systems and obtain explicit analytic equations of *** falling U-chain,the mass matrix is ***-order constraints are used to get the constraint force and equations of motion and the numerical simulation is *** results show that the chain tip falls faster than the freely falling *** fish robot,two-joint Carangiform fish robot is focused ***-steady wing theory is used to approximately calculate fluid lift force acting on the caudal *** on the obtained explicit analytic equations of motion(the mass matrix is singular),propulsive characteristics of each part of the fish robot are *** these two cases of U chain and fish robot,how to use Udwadia-Kalaba equation to obtain the dynamical model is shown and the modeling methodology for multi-body systems is *** is also shown that Udwadia-Kalaba theory is applicable to systems whether or not their mass matrices are *** the whole process of applying Udwadia-Kalaba equation,Lagrangian multipliers and quasi-coordinates are not ***-Kalaba theory is creatively applied to dynamical modeling of falling U-chain and fish robot problems and explicit analytic equations of motion are obtained.

关键词： Udwadia-Kalaba equation multi-body systems falling U-chain fish robot

Thermal Stability of Fe_2O_3 Nanowires

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Journal of Materials Science & Technology 2008年第4期24卷 594-596页

作者： Xiongdian ZhanG Qin han zhao DONG Yingying XU han ZhanG State Key Laboratory for Mesoscopic Physics Department of Physics Peking University. Beijing 100871 China

The thermal stability of α-Fe203 and γ-Fe2O3 nanowires was studied by post annealing the samples at different temperatures. Before and after annealing, the samples were characterized by X-ray diffraction and scanning electron microscopy. The α-Fe2O3 nanowires are stable at the temperatures up to 600℃, and the crystalline structure becomes more perfect after annealing. This behavior supplies a way to improve the quality of the α-Fe2O3 nanowires. The γ-Fe2O3 nanowires become unstable when annealed at 350℃. Raman spectra of both nanowires have been measured, which also indicate that the γ-Fe203 nanowires are transformed into α-Fe2O3 under the strong laser beam.

关键词： Fe2O3 nanowire Thermal stability Structural transformation

Udwadia–Kalaba Equation for Constrained Mechanical Systems:Formulation and Applications

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Chinese Journal of Mechanical Engineering 2018年第6期31卷 11-24页

作者： Xiao-Min zhao Ye-Hwa Chen han zhao Fang-Fang Dong School of Automotive and Transportation Engineering Hefei University of TechnologyHefei 230009China The George W.Woodruff School of Mechanical Engineering Georgia Institute of TechnologyAtlanta 30332USA School of Mechanical Engineering Hefei University of TechnologyHefei 230009China

There are many achievements in the field of analytical mechanics, such as Lagrange Equation, Hamilton’s Principle, Kane’s Equation. Compared to Newton–Euler mechanics, analytical mechanics have a wider range of applications and the formulation procedures are more mathematical. However, all existing methods of analytical mechanics were proposed based on some auxiliary variables. In this review, a novel analytical mechanics approach without the aid of Lagrange’s multiplier, projection, or any quasi or auxiliary variables is introduced for the central problem of mechanical systems. Since this approach was firstly proposed by Udwadia and Kalaba, it was called Udwadia–Kalaba Equation. It is a representation for the explicit expression of the equations of motion for constrained mechanical systems. It can be derived via the Gauss’ s principle, d’Alembert’s principle or extended d’Alembert’s principle. It is applicable to both holonomic and nonholonomic equality constraints, as long as they are linear with respect to the accelerations or reducible to be that form. As a result, the Udwadia–Kalaba Equation can be applied to a very broad class of mechani?cal systems. This review starts with introducing the background by a brief review of the history of mechanics. After that, the formulation procedure of Udwadia–Kalaba Equation is given. Furthermore, the comparisons of Udwadia–Kalaba Equation with Newton–Euler Equation, Lagrange Equation and Kane’s Equation are made, respectively. At last, three di erent types of examples are given for demonstrations.

关键词： Udwadia–Kalaba Equation Mechanical system Constraint Moore–Penrose inverse