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A Thermo-Tunable Metamaterial as an Actively Controlled Broadband Absorber

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Engineering 2023年第1期20卷 143-152页

作者： xiao-Chang xing Yang Cao xiao-Yong Tian Lingling Wu State Key Laboratory for Manufacturing Systems Engineering Xi’an Jiaotong UniversityXi’an 710049China

Metamaterials have attracted increasing attention in recent years due to their powerful abilities in manipulating electromagnetic (EM) waves. However, most previously reported metamaterials are unable to actively control full-band EM waves. In this paper, we propose a thermo-tunable broadband metamaterial (T-TBM) using paraffin-based composites (PD-Cs) with different phase transition temperatures. Active control of the T-TBM reflection loss peaks from low to high frequency is realized by manipulating the solid–liquid state of the PD-Cs at different phase transition temperatures. The absorption peak bandwidth (where the reflection loss value is less than −30 dB) can be changed, while the broad bandwidth absorption (where the reflection loss value is less than −10 dB) is satisfied by adjusting the temperature of the T-TBM. It is shown that the stagnation of the phase transition temperature of the PD-Cs in the T-TBM provides a time window for actively controlling the EM wave absorption response under different thermal conditions. The device has a broad application prospect in the fields of EM absorption, intelligent metamaterials, multifunctional structural devices, and more.

关键词： Metamaterials Active control Thermally tunable Br oadband absorption

Wormhole Solution in Vacuum Brans-Dicke Theory with Cosmological Constant

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Chinese Physics Letters 1996年第6期13卷 405-408页

作者： xiao xing-guo ZHU Jian-yang Department of Physics Tianjin College of EducationTianjin 300020 Department of Physics Jiangxi Normal UniversityNanchang 330027

In this paper,we give an Euclidean wormhole solution in the Brans-Dicke theory with cosmological *** show that this wormhole is unlike all the others,its configuration is *** throat radius of the wormhole will increas... 详细信息

关键词： Brans Dicke cosmic

DIRECT MEASUREMENT OF WEAK DEPLETION FORCE BETWEEN TWO SURFACES

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Chinese Journal of Polymer Science 2011年第1期29卷 1-11页

作者： Xiang-jun Gong xiao-chen xing xiao-ling Wei To Ngai Department of Chemistry the Chinese University ofHong Kong Shatin N.T. Hong Kong China Department of Physics the Chinese University ofHong Kong Shatin N.T. Hong Kong China

In a mixture of colloidal particles and polymer molecules, the particles may experience an attractive ＂depletion force＂ if the size of the polymer molecule is larger than the interparticle separation. This is because individual polymer molecules experience less conformational entropy if they stay between the particles than they escape the inter-particle space, which results in an osmotic pressure imbalance inside and outside the gap and leads to interparticle attraction. This depletion force has been the subject of several studies since the 1980s, but the direct measurement of this force is still experimentally challenging as it requires the detection of energy variations of the order of kBT and beyond. We present here our results for applying total internal reflection microscopy （TIRM） to directly measure the interaction between a free-moving particle and a flat surface in solutions consisting of small water-soluble organic molecules or polymeric surfactants. Our results indicate that stable nanobubbles （ca. 150 nm） exist free in the above aqueous solutions. More importantly, the existence of such nanobubbles induces an attraction between the spherical particle and flat surface. Using TIRM, we are able to directly measure such weak interaction with a range up to 100 nm. Furthermore, we demonstrate that by employing thermo^sensitive microgel particles as a depleting agent, we are able to quantitatively measure and reversibly control kBT-scale depletion attraction as function of solution pH.

关键词： Depletion interaction Total internal reflection microscopy (TIRM) Nanobubbles Microgel particles

Enhancing point defect scattering in copper antimony selenides via Sm and S Co-doping

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Rare Metals 2018年第4期37卷 290-299页

作者： Tian-Hua Zou Wen-Jie Xie Marc Widenmeyer xing-xing xiao xiao-Yin Qin Anke Weidenkaff Institute for Materials Science University of Stuttgart 70569Stuttgart Germany Key Laboratory of Materials Physics Institute of Solid StatePhysics Chinese Academy of Sciences Hefei 230031 China

Doping- and alloying-induced point defects lead to mass and strain field fluctuations which can be used as effective strategies to decrease the lattice thermal conductivity and consequently boost the performance of thermoelectric materials. Herein, we report the effects of Sm and S co-doping on thermoelectric transport properties of copper antimony selenides in the temperature range of 300 K 〈 T〈 650 K. Through the Callaway model, it demonstrates that Sm and S co-doping induces strong mass differences and strain field fluctuations in Cu3SbSe4. The results prove that doping with suitable elements can increase point defect scattering of heat-carrying phonons, leading to a lower thermal conductivity and a better ther- moelectric performance. The highest figure of merit （ZT） of - 0.55 at 648 K is obtained for the Sm and S co-doped sample with nominal composition of Cu2.995Sm0.005Sb- Se3.95S0.05, which is about 55% increase compared to the ZT of pristine Cu3SbSe4.

关键词： Thermoelectric Point defect scatteringCu3SbSe4 Lattice thermal conductivity

Regular Space-like Hypersurfaces in S1^m+1 with Parallel Para-Blaschke Tensors

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Acta Mathematica Sinica,English Series 2017年第10期33卷 1361-1381页

作者： xing xiao LI Hong Ru SONG School of Mathematics and Information Science He'nan Normal UniversityXinxiang 453007P.R.China

In this paper, we give a complete conformal classification of the regular space-like hyper- surfaces in the de Sitter Space S~＋1 with parallel para-Blaschke tensors.

关键词： Conformal form parallel para-Blaschke tensor conformal metric conformal second fun-damental form constant scalar curvature constant mean curvature

On the Asymptotic Behavior of the Storage Process Fed by a Markov Modulated Brownian Motion

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Acta Mathematicae Applicatae Sinica 2008年第1期24卷 75-84页

作者： xiao-yu xing Xue-qiang Wang School of Mathematical Sciences and LPMC Nankai University Tianjin 300071 China

Consider a storage model fed by a Markov modulated Brownian motion. We prove that the stationary distribution of the model exits and that the running maximum of the storage process over the interval [0, t] grows asymp... 详细信息

关键词： Markov modulated Brownian motion stationary distribution

Survival Probability of Population-size-dependent Branching Processes in Random Environments

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Acta Mathematicae Applicatae Sinica 2016年第2期32卷 477-484页

作者： Shi-xia MA xiao-yu xing School of Sciences Hebei University of Technology

The class of population-size-dependent branching processes in independent identically distributed random environments is investigated. Under the critical case and appropriate moment assumption, we establish an asympto... 详细信息

关键词： branching processes population-size-dependent processes random environments survival proba-bility

Isometric Immersions of Higher Codimension in to the Product S~κ×H^(n+p-k)

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Acta Mathematica Sinica,English Series 2014年第12期30卷 2146-2160页

作者： xing xiao LI Tian Qun ZHANG Department of Mathematics He'nan Normal University Luoyang No.43 Middle School

In this paper,we obtain a sufficient and necessary condition for a simply connected Riemannian manifold（M^n,g） to be isometrically immersed,as a submanifold with codimension p 〉 1,into the product S^k×H^n＋p＋k of... 详细信息

关键词： Isometric immersions of higher codimension product structure spheres and hyperboloids

Immersed Hypersurfaces in the Unit Sphere S^(m+1) with Constant Blaschke Eigenvalues

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Acta Mathematica Sinica,English Series 2007年第3期23卷 533-548页

作者： xing xiao LI Feng Yun ZHANG Department of Mathematics He'nan Normal University Xinxiang 453007 He'nan P. R. China

For an immersed submanifold x ： M^m→ Sn in the unit sphere S^n without umbilics, an eigenvalue of the Blaschke tensor of x is called a Blaschke eigenvalue of x. It is interesting to determine all hypersurfaces in Sn with constant Blaschke eigenvalues. In this paper, we are able to classify all immersed hypersurfaces in S^m＋1 with vanishing MSbius form and constant Blaschke eigenvalues, in case （1） x has exact two distinct Blaschke eigenvalues, or （2） m = 3. With these classifications, some interesting examples are also presented.

关键词： Moebius form Blaschke eigenvalues Blaschke tensor MSbius metric MSbius second fundamental form