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Epsilon-near-zero or mu-near-zero materials composed of dielectric photonic crystals

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science China(Information sciences) 2013年第12期56卷 148-157页

作者： LUO Jie lai Yun Wave-Functional Materials Lab Department of Physics Soochow University

We theoretically demonstrate that at certain frequencies two-dimensional dielectric photonic crystals(PCs)may be regarded as either epsilon-near-zero or mu-near-zero *** show that the transmission through a slab of such materials upon normal incidence is normally non-unity and decays with slab ***,when the incident angle increases slightly,the transmittance experiences a dramatic increase due to the Brewster *** combination of the tunneling and resonance efects makes such materials good candidates for almost perfect bending waveguides and cloaking in *** zero index also enables applications of focusing and directive *** last,the distinction between the single-zero and double-zero media is *** all of the above results,the numerical simulations perfectly match with theoretical predictions from the efective medium analysis.

关键词： photonic crystal epsilon-near-zero material mu-near-zero material efective medium transmission properties Brewster efect

A sequential Partial Optimization Algorithm for Design of Near Linear-Phase IIR Digital Differentiators

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Chinese Journal of Electronics 2019年第5期28卷 968-977页

作者： MENG Hailong lai Xiaoping YI Huoping key Lab for IOT and Information Fusion Technology of Zhejiang Hangzhou Dianzi University Institute of Information and Control Hangzhou Dianzi University

The linear phase is a major characteristic of digital differentiators in many signal processing applications. This study presents a sequential partial optimization method for designing a fullband infinite impulse response digital differentiator with a near linear phase. To achieve a near linear phase, the group delay is treated as an optimization variable, and the maximum phase error is minimized within a constrained *** each iteration of the algorithm, in addition to the whole numerator and group delay, only one secondorder denominator factor is optimized. The necessary and sufficient stability triangles are applied to insure the stability of the differentiators, and the Gauss-Newton strategy is used to handle the nonconvexity of the design problems. Design examples show that the proposed method outperforms several state-of-the-art methods in terms of the maximum phase deviation from the desired linear phase.

关键词： Digital differentiator Linear phase sequential partial optimization Gauss-Newton strategy Mathematical programming

study on microscale adhesion between solid surfaces with scanning probe

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science China(Technological sciences) 2013年第12期56卷 2934-2952页

作者： lai TianMao HUANG Ping school of Mechanical and Automotive Engineering South China University of Technology

The adhesion between two parallel solid surfaces is of great interest with the rapid development of micro-nano devices and *** adhesion forces between a flat tip with a diameter^1.7μm and some surface have been determined by recording the force-displacement curves with an atomic force microscope(AFM).The flat tip is used to prevent wear and mimic the adhesion between two parallel *** free energy of the solid surface is calculated by the contact angles between the probe liquids and the *** adhesion force between parallel solid surfaces cannot be predicted by the theory of thermodynamic surface free *** adhesion measurements were carried out under ambient conditions,in a nitrogen-filled glove box,under distilled water,and under potassium chloride(kCl)*** outcome shows that the real contact area without the applied load is only a small proportion of the apparent contact *** measurement stability and repeatability of adhesion by the AFM depend on the surface characterization,measurement methods and the *** different environments,there are different interactions and factors affecting the adhesion force,and the dominant interactions and factors may be different *** various interactions and factors are mutually coupled to determine the final adhesion force.

关键词： micro-scale adhesion force atomic force microscope force-displacement curve flat tip surface free energy

Fast two-dimensional weighted least squares techniques for the design of two-dimensional finite impulse response filters

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控制理论与应用（英文版） 2013年第2期11卷 180-185页

作者： Ruijie ZHAO Xiaoping lai school of Mechanical Electrical and Information Engineering Shandong University at Weihai Institute of Information and Control Hangzhou Dianzi University

This paper focuses on the design of two-dimensional （2D） quadrantally symmetric finite impulse response （FIR） filters, and presents three very efficient algorithms for the weighted least squares （WLs） design with a weight matrix that assigns four different weights to four different frequency bands. The first algorithm seeks for iterative solutions to the matrix equation describing the optimality condition of the design problem. The second algorithm aims at the limit solution of the solution sequence to the first algorithm, analytically obtained by using matrix diagonalization techniques. The third algorithm belongs to the category of iterative reweighting techniques. It uses the second algorithm as its iteration core, and aims at reducing the maximum magnitude error of the filter by iteratively adjusting the four entry values of the weight matrix. Design examples are provided to demonstrate the performance of the proposed algorithms.

关键词： 2D FIR filters Diagonalization Quadrantal symmetry WLs design

ON THE EMBEDDING OF TOP IN THE CATEGORY OF sTRATIFIED L-TOPOLOGICAL sPACEs

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Chinese Annals of Mathematics,series B 2005年第2期26卷 219-228页

作者： lai Hongliang ZHANG Dexue Department of Mathematics Sichuan UniversityChengdu 610064China Department of Mathematics Sichuan UniversityChengdu 610064China

Let L be a meet continuous lattice. It is proved that the category Top of topological spaces can be embedded in the category of strati?ed L-topological spaces as a concretely both re?ective and core?ective full subcat... 详细信息

关键词： Continuous lattice L-topological space Re?ective subcategory Core-flective subcategory

User centric dynamic web information visualization

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science China(Information sciences) 2013年第5期56卷 36-49页

作者： sALEHEEN shibli lai Wei Faculty of Information and Communication Technologies Swinburne University of TechnologyHawthorn 3122VictoriaAustralia

Visualization of information after retrieval from the World Wide Web is a very challenging task because of the huge amount of data in *** on rules,information is retrieved through mining techniques and then visualized in different *** web-graph is one way for users to visualize web data and its *** because of its huge size,the web-graph lacks simplicity for end *** clustering plays a very important role in reducing the complexity of the web graph by making it compact and simple,existing clustering techniques are insufficient to provide personalized visualization for ***,these clustering techniques end up showing the same clustered graph to every user,despite their varying *** work aims to make information visualization personalized based on user interests;to provide a good first impression of web information to end users;to make web navigation easier;and to create scope for further ***,we develop a system for clustering which first considers user interests and then visualizes the clustered web graph to make the information more useful to the end *** this paper,we present some experimental examples that show the improvements achieved by our approach over existing ones.

关键词： information retrieval user profile clustering personalization visualization

Experimental investigation on the wing-wake interaction at the mid stroke in hovering flight of dragonfly

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science China(Physics,Mechanics & Astronomy) 2012年第11期55卷 2167-2178页

作者： lai GuoJun sHEN GongXin FFFOM Laboratory School of Aeronautic Science and EngineeringBeihang UniversityBeijing 100191China

This paper focuses on flow structures of the wing-wake interaction between the hind wing and the wake of the forewing in hovering flight of a dragonfly since there are arguments whether the wing-wake interaction is useful or not.A mechanical flapping model with two tandem wings is used to study the *** the device,two identical simplified model wings are mounted to the flapping model and they are both scaled up to keep the Reynolds number similar to those of dragonfly in hovering flight since our experiment is conducted in a water *** kinetic pattern of dragonfly(Aeschna juncea) is chosen because of its special interesting asymmetry.A multi-slice phase-locked stereo particle image velocimetry(PIV) system is used to record flow structures around the hind wing at the mid downstroke(t/T=0.25) and the mid upstroke(t/T=0.75).To make comparison of the flow field between with and without the influence of the wake,flow structures around a single flapping wing(hind wing without the existence of the forewing) at these two stroke phases are also recorded.A local vortex identification scheme called swirling strength is applied to determine the vortices around the wing and they are visualized with the iso-surface of swirling *** paper also presents contour lines of z at each spanwise position of the hind wing,the vortex core position of the leading edge vortex(LEV) of hind wing with respect to the upper surface of hind wing,the circulation of the hind wing LEV at each spanwise position and so *** results show that dimension and strength of the hind wing LEV are impaired at the mid stroke in comparison with the single wing LEV because of the downwash from the *** results also reveal that a wake vortex from the forewing traverses the upper surface of the hind wing at the mid downstroke and its distance to the upper surface is about 40% of the wing chord *** the instant,the distance of the hind wing LEV to the upper surface is abo

关键词： dragonfly hovering flight particle image velocimetry (PIV) flow interaction leading edge vortex

Vagus nerve stimulation in intracerebral hemorrhage:the need for further research

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Neural Regeneration Research 2025年第11期20卷 3213-3214页

作者： sheharyar s.Baig Ali N.Ali Arshad Majid sheffield Institute for Translational Neuroscience Division of NeuroscienceThe University of SheffieldSheffieldUK

Vagus nerve stimulation(VNs)and stroke:stroke is the second leading cause of death and the third leading cause of disability worldwide(Baig et al.,2023).There have been significant paradigm shifts in the management of acute ischemic stroke through mechanical *** chronic ischemic stroke,invasive VNs paired with rehabilitation is associated with a significant increase in upper limb motor recovery and is FDA-approved(Baig et al.,2023).There are no treatments of similar efficacy in acute intracerebral hemorrhage(ICH)where several promising trials,e.g.,TICH-2,sTOP-AUsT,and TRAIGE did not show improvements in functional outcomes(Puy et al.,2023).

关键词： stimulation acute

New constructions for (multiparty) one-round key exchange with strong security

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science China(Information sciences) 2018年第5期61卷 332-337页

作者： Zheng YANG Junyu lai school of Computer science and Engineering Chongqing University of Technology Department of Computer science University of Helsinki school of Aeronautics and Astronautics University of Electronic Science and Technology of China

Dear editor,One-round key exchange(ORkE)represents a special class of two-message key *** enables two parties to establish a shared session key within only one communication *** first merit of ORkE is its communication efficiency,particularly because two parties are able to simultaneously run the protocol ***,the messages of two session participants(in an ORkE protocol)are completely independent.

关键词： New constructions for multiparty Eph DDH PFs