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Classical imaging with undetected photons using four-wave mixing in silicon core fibers

Photonics Research 2023年第2期11卷 137-142页

作者： m.HUANG D.WU H.REN L.SHEN T.W.HAWKINS j.BALLATO U.j.GIBSON m.BERESNA R.SLAVíK j.E.SIPE m.LISCIDINI A.C.PEACOCK Optoelectronics Research Centre University of SouthamptonSouthamptonSO171BJUK School of Optoelectronic Engineering and Instrumentation Science Dalian University of TechnologyDalian 116024China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China Centre for Optical materials Science and Engineering Technologies and Department of materials Science and Engineering Clemson UniversityClemsonSouth Carolina 29634USA Department of Physics University of TorontoTorontoOntario M5S 1A7Canada Department of Physics University of PaviaI-27100 PaviaItaly

Undetected-photon imaging allows for objects to be imaged in wavelength regions where traditional components are unavailable. Although first demonstrated using quantum sources, recent work has shown that the technique also holds with classical beams. To date, however, all the research in this area has exploited parametric downconversion processes using bulk nonlinear crystals within free-space systems. Here, we demonstrate undetectedphoton-based imaging using light generated via stimulated four-wave mixing within highly nonlinear silicon fiber waveguides. The silicon fibers have been tapered to have a core diameter of915 nm to engineer the dispersion and reduce the insertion losses, allowing for tight mode confinement over extended lengths to achieve practical nonlinear conversion efficiencies(-30 dB) with modest pump powers(48 m W). Both amplitude and phase images are obtained using classically generated light, confirming the high degree of spatial and phase correlation of our system. The high powers(>10 nW) and long coherence lengths(>4 km) associated with our large fiber-based system result in high contrast and stable images.

关键词： mixing fibers nonlinear

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High-dimensional neural network potentials for magnetic systems using spin-dependent atom-centered symmetry functions

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npj Computational materials 2021年第1期7卷 1541-1551页

作者： marco Eckhoff jörg Behler Universität Göttingen Institut für Physikalische ChemieTheoretische ChemieTammannstrasse 637077 GöttingenGermany Universität Göttingen International Center for Advanced Studies of Energy Conversion(ICASEC)Tammannstrasse 637077 GöttingenGermany

machine learning potentials have emerged as a powerful tool to extend the time and length scales of first-principles quality ***,most machine learning potentials cannot distinguish different electronic spin arrangements and thus are not applicable to materials in different magnetic *** we propose spin-dependent atom-centered symmetry functions as a type of descriptor taking the atomic spin degrees of freedom into *** used as an input for a high-dimensional neural network potential(HDNNP),accurate potential energy surfaces of multicomponent systems can be constructed,describing multiple collinear magnetic *** demonstrate the performance of these magnetic HDNNPs for the case of manganese oxide,*** method predicts the magnetically distorted rhombohedral structure in excellent agreement with density functional theory and *** efficiency allows to determine the Néel temperature considering structural fluctuations,entropic effects,and *** method is general and is expected to be useful also for other types of systems such as oligonuclear transition metal complexes.

关键词： magnetic symmetry neural

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巴基斯坦立方星ICUBE-Q任务综述

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中国航天 2024年第7期 45-56页

作者：吴树范 Qamarul Islam 曾小勤 m.Rizwan mughal 慕忠成 Khurram Khurshid 上海交通大学航空航天学院巴基斯坦空间技术研究所

作为“嫦娥”六号任务搭载的国际载荷之一,巴基斯坦ICUBE-Q立方星于2024年5月3日随“嫦娥”六号探测器发射升空。5月8日16时,ICUBE-Q在周期为12h的环月大椭圆轨道的远月点附近与“嫦娥”六号轨道器分离,随后成功拍摄第一幅影像。任务实... 详细信息

作为“嫦娥”六号任务搭载的国际载荷之一,巴基斯坦ICUBE-Q立方星于2024年5月3日随“嫦娥”六号探测器发射升空。5月8日16时,ICUBE-Q在周期为12h的环月大椭圆轨道的远月点附近与“嫦娥”六号轨道器分离,随后成功拍摄第一幅影像。任务实现“成功分离,获得遥测”的既定目标,取得圆满成功。重点从卫星总体方案、关键技术和解决途径、卫星总体研制情况、在轨运维情况及研制经验等多个方面对ICUBE-Q立方星进行介绍,为未来深空探月纳卫星任务积累技术基础。

关键词：立方星对月成像在轨智能处理地月测控

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Characterization of the ZnO thin film prepared by single source chemical vapor deposition under low vacuum condition

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Science China(Technological Sciences) 2003年第4期46卷 355-360页

作者：邓宏 B.GONG A.j.Petrella j.j.Russell R.N.Lamb School of microelectronics and Solid State Electronics University of Electronic Scienceand Technology of China School of Chemistry the University of New South Wales Sydney2052Australia

A novel technique is developed for growing high quality ZnO thin films by means of single source chemical vapor deposition (SS CVD) under low vacuum conditions with the precursor of zinc carbamate Zn4O(CO2Net2)6. SEm, AFm and XRD studies show that the resultant thin films have high density, smooth surface, uniform polycrystalline structure and excellent c-axis orientation. XPS investigation indicates that the ZnO films are free of decomposed precursor residues in the bulk. Careful quantitative XPS analysis reveals that the ZnO films are stoichiometric with O/Zn atomic ratio very close to that of ZnO single crystal.

关键词： ZnO thin film, low vacuum deposition, SSCVD.

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PHOTOCATALYTIC PERFORmANCE OF PLASmA SPRAYED TiO_2-ZnFe_2O_4 COATINGS

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Acta metallurgica Sinica(English Letters) 2005年第3期18卷 363-368页

作者： Y.Zeng j.T.Liu W.j.Qian j.H.Gao ShanghaiInstituteofCeramics TheChineseAcademyofSciencesShanghai200050China

A novel TiO2-ZnFe2O4 coating is prepared by plasma spraying. The effects of spra ying parameters and the composition of powders on the microstructure, surface mo rphology and photo-absorption of plasma sprayed coatings are studied. The photoc atalytic efficiency of the as-sprayed coatings is evaluated through the photo mi neralization of methylene blue. It was found that TiO2 coatings can decompose me thylene blue under the illumination of ultraviolet rays, and the degrading effic iency is improved with an increase in the content of FeTiO3 in the coatings. How ever, the presence of large amount of ZnFe2O4 compound will substantially lower the photocatalytic efficiency of the TiO2-ZnFe2O4 coatings for the unfavorable p hoto-excited electron-hole transfer process.

关键词： plasma spraying photocatalytic activity TiO2 ZnFe2O4

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Effect of tilt angle on the performance and electrical parameters of a PV module:Comparative indoor and outdoor experimental investigation

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Energy and Built Environment 2022年第3期3卷 278-290页

作者： m.A.A.mamun m.m.Islam m.Hasanuzzaman jeyraj Selvaraj Higher Institution Centre of Excellence(HICoE) UM Power Energy Dedicated Advanced Centre(UMPEDAC)Level 4Wisma R&DUniversity of MalayaJalan Pantai Baharu59990 Kuala LumpurMalaysia

Photovoltaic(PV)system’s performance is significantly affected by its orientation and tilt *** investigation(indoor and outdoor)has been carried out to trace the variation in PV performance and electrical parameters at varying tilt angles in malaysian *** were two experimental modus:1)varying module tilt under constant irradiation level,2)varying irradiation intensity at the optimum tilt set *** the former scheme,the irradiation level was maintained at 750 W/m^(2),and for the later arrangement,the module tilt angle was varied from 0 o to 80 o by means of a single-axis *** show that under constant irradiation of 750 W/m^(2),every 5 o increase in tilt angle causes a power drop of 2.09 W at indoor and 3.45 W at *** contrast,for the same condition,efficiency decreases by 0.54%for indoor case and by 0.76%at *** the other hand,for every 100 W/m^(2)increase in irradiation,solar cell temperature rises by 7.52℃at indoor and by 5.67℃at *** of module electrical parameters,open-circuit voltage,short-circuit current,maximum power point voltage and maximum power point current drops substantially with increasing tilt angle,whereas fill factor drops rather *** experimental investigation confirms that the optimum tilt angle at malaysian conditions is 15 o and orienting a PV module this angle will maximize the sun’s energy captured and thereby enhance its performance.

关键词： Photovoltaic Irradiation intensity Tilt angle PV performance module electrical parameters

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Small Zeros of Additive Forms in Several Variables

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Acta mathematica Sinica,English Series 1998年第1期14卷 57-66页

作者： j. S. Hwang Institute of mathematics Academia Sinica Taipei Taiwan 11529 China

Let f（X） be an additive form defined by f（X）=f（x1. x2,…,xs）=σ1α1x1k+σα2x2k+…+σsαsxsk, where αo≠0 is integer, i=1, 2,…, s. In 1979, Schmidt proved that if ε>0 then there is a large constant C（k, ε） such that for s≥C（k, ε） the equation f（X）=0 has a nontrivial integer solution in σ1. σ2,…σs, x1, x2…,xs satisfying σi=±1 and |xi|≤Aε, i=1, 2.…,s where A=max|ai|. Schmidt did not estimate this constant C（k. ε） since it would be extremely large. In this paper, we prove the following result: Theorem 1 If log A≤1/ε,then C（k,ε）≤max （2/ε,20）; if log A>1/ε,A is sufficiently larye and 1/2A≤5≤|ai|≤A,i=1. 2,…, s, then C（k,ε）≤c1c2p and if the last condition is omitted, then C（k. ε）≤[4/ε]c1c2,where c1={2k+1 for≤k≤11 [5k2log k] for k≥12, c2=100c1k22k+c12 and p=2[log 2c1/ε]. We note that the inequality in the first case is sharp but not in the second case.

关键词： Additive form Subset sums Small zeros

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A refined finite element method for bending analysis of laminated plates integrated with piezoelectric fiber-reinforced composite actuators

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Acta mechanica Sinica 2018年第4期34卷 689-705页

作者： j.Rouzegar A.Abbasi Department of mechanical and Aerospace Engineering Shiraz University of Technology

This research presents a finite element formulation based on four-variable refined plate theory for bending analysis of cross-ply and angle-ply laminated composite plates integrated with a piezoelectric fiber-reinforced composite actuator under electromechanical loading. The four-variable refined plate theory is a simple and efficient higher-order shear deformation theory, which predicts parabolic variation of transverse shear stresses across the plate thickness and satisfies zero traction conditions on the plate free surfaces. The weak form of governing equations is derived using the principle of minimum potential energy, and a 4-node non-conforming rectangular plate element with 8 degrees of freedom per node is introduced for discretizing the domain. Several benchmark problems are solved by the developed mATLAB code and the obtained results are compared with those from exact and other numerical solutions, showing good agreement.

关键词： Finite elementmethod Laminated plate Piezoelectric fiber-reinforced composite(PFRC)actuator Piezoelectric Refined plate theory Smart structures

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NUmERICAL SImULATION OF FLOWS FOR SECOND-ORDER VISCOELASTIC FLUID COUPLED WITH HEAT TRANSFER BY DIFFERENTIAL QUADRATURE mETHOD

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journal of Hydrodynamics 2005年第2期17卷 209-215页

作者： AL-SAIF A.S.j. Shanghai Institute of Applied mathematics and mechanics Shanghai University Shanghai 200072 China

The problem of two-dimensional steady flow of an incompressible second-order viscoelastic fluid coupled with heat transfer between parallel plates was considered. A viscous dissipation function was included in the energy equation. When the elastic property of the fluid is weaker, the zeroth-order and first-order approximate governing equations were obtained by means of the perturbation method. To understand the behavior of flow near the tube wall, the half-domain was divided into two sub-domains, in which one is a thin layer near the wall called the inner domain and the remainder is called the outer domain. The governing equations in the inner domain and in the outer domain were discretized respectively by using the Differential Quadrature method (DQm). The matching conditions at the interface between the inner and outer domains were presented. An iterative method for solving these discretized equations was given in this paper. The numerical results obtained agree with existing results.

关键词： momentum equations heat equation second-order viscoelastic fluid Differential Quadrature method (DQm)

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Bio-Imitation of mexican migration Routes to the USA with Slime mould on 3D Terrains

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journal of Bionic Engineering 2013年第2期10卷 242-250页

作者： Andrew Adamatzky Genaro j martinez Department of Computer Sciences University of the West of England Bristol BS16 1QY UK Escuela Superior de Computo Instituto Politecnico Nacional Mexico

Plasmodium ofPhysarum polycephalum （P. polycephalum） is a large single cell visible by an unaided eye. It shows sophisticated behavioural traits in foraging for nutrients and developing an optimal transport network of protoplasmic tubes spanning sources of nutrients. When placed in an environment with distributed sources of nutrients the cell computes＇ an optimal graph spanning the nutrients by growing a network of protoplasmic tubes. P. polycephalum imitates development ofman-made transport networks of a country when configuration of nutrients represents major urban areas, We employed this feature of the slime mould to imitate mexican migration to USA. The mexican migration to USA is the World＇s larger migration system. We bio-physically imitated the migration using slime mould P. poIycephalum. In laboratory experiments with 3D Nylon terrains of USA we imitated development of migratory routes from mexico-USA border to ten urban areas with high concentration of mexican migrants. From results of laboratory experiments we extracted topologies of migratory routes, and highlighted a role of elevations in shaping the human movement networks.

关键词： biomimetics bio-inspired computing migration routes slime mould

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