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Universal bound on sampling bosons in linear optics and its computational implications

National Science Review 2019年第4期6卷 719-729页

作者： man-Hong Yung Xun gao Joonsuk Huh Shenzhen Institute for Quantum Science and Engineering and Department of Physics Southern University of Science and Technology Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Central Research Institute Huawei Technologies Center for Quantum Information Institute for Interdisciplinary Information SciencesTsinghua University Department of Chemistry Sungkyunkwan University

In linear optics, photons are scattered in a network through passive optical elements including beam splitters and phase shifters, leading to many intriguing applications in physics, such as Mach–Zehnder interferometry, the Hong–Ou–mandel effect, and tests of fundamental quantum mechanics. Here we present the fundamental limit in the transition amplitudes of bosons, applicable to all physical linear optical networks. Apart from boson sampling, this transition bound results in many other interesting applications,including behaviors of Bose–Einstein condensates(BEC) in optical networks, counterparts of Hong–Ou–mandel effects for multiple photons, and approximating permanents of matrices. In addition,this general bound implies the existence of a polynomial-time randomized algorithm for estimating the transition amplitudes of bosons, which represents a solution to an open problem raised by Aaronson and Hance(Quantum Inf Comput 2012; 14: 541–59). Consequently, this bound implies that computational decision problems encoded in linear optics, prepared and detected in the Fock basis, can be solved efficiently by classical computers within additive errors. Furthermore, our result also leads to a classical sampling algorithm that can be applied to calculate the many-body wave functions and the S-matrix of bosonic particles.

关键词： boson sampling quantum optics quantum supremacy linear optics computational complexity

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Land development suitability analysis for transport planning evaluation and optimization in mountainous ecological region

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Journal of Mountain Science 2022年第3期19卷 862-873页

作者： ZHU gao-ru WANG man LI qi-li LIU Jie ZHAO Yan-ni gao Jia-wei XU Hong-lei Laboratory of Transport Pollution Control and Monitoring Technology Transport Planning and Research InstituteMinistry of TransportBeijing 100028China College of Urban and Environmental Sciences Peking UniversityBeijing 100871China Key Laboratory for Environmental and Urban Sciences School of Urban Planning&DesignShenzhen Graduate SchoolPeking UniversityShenzhen 518055China

Transportation planning is a critical component for creating an orderly,intensive,and sustainable pattern of land *** comprehensively considering the potential and suitability of transport construction,a comprehensive method combining resources and environmental carrying capacity(RECC)and land development suitability(LDS)was developed by using techniques of GIS,analytic hierarchy process(AHP)and threedimensional magic *** Aba prefecture in Sichuan Province of Southwest China as a case study,LDS for transportation was analyzed from three aspects,including overall planning layout,different transport modes,and transportation *** results showed that the transport planning scales of most counties in Aba were suitable,and the order of LDS of different transport modes was railway>highway=superhighway>tourism track,which already included 42 new transportation *** found that two counties(Maoxian County and Jiuzhaigou County)should improve the ecological protection level of transportation,in which the railway network construction should be encouraged,and some transportation projects with low LDS should be postponed or constructed *** suggest the combination of RECC and LDS for transportation could enhance the territorial space optimization and sustainable transport construction.

关键词： Land development suitability Resources and environment carrying capacity Transport planning Evaluation Optimization Spatial analysis Mountainous ecological region

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Repetitive transcranial magnetic stimulation for lower extremity motor function in patients with stroke:a systematic review and network meta-analysis

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Neural Regeneration Research 2021年第6期16卷 1168-1176页

作者： Yun-Juan Xie Yi Chen Hui-Xin Tan qi-Fan Guo Benson Wui-man Lau qiang gao Department of Rehabilitation Medicine West China HospitalSichuan UniversityChengduSichuan ProvinceChina Key Laboratory of Rehabilitation Medicine in Sichuan Province West China HospitalSichuan UniversityChengduSichuan ProvinceChina Department of Rehabilitation Sciences The Hong Kong Polytechnic UniversityHong Kong Special Administrative RegionChina

Transcranial magnetic stimulation,a type of noninvasive brain stimulation,has become an ancillary therapy for motor function *** previous studies have focused on the effects of repetitive transcranial magnetic stimulation(rTMS)on motor function in stroke *** have been relatively few studies on the effects of different modalities of rTMS on lower extremity motor function and corticospinal excitability in patients with *** MEDLINE,Embase,Cochrane Library,ISI Science Citation Index,Physiotherapy Evidence Database,China National Knowledge Infrastructure Library,and *** databases were *** or crossover randomized controlled trials that addressed the effectiveness of rTMS in patients with stroke,published from inception to November 28,2019,were *** pairwise meta-analysis was conducted using R version 3.6.1 with the“meta”*** network analysis using the Markov chain Monte Carlo algorithm was conducted to investigate the effectiveness of different rTMS protocol *** meta-analysis results of 18 randomized controlled trials regarding lower extremity motor function recovery revealed that low-frequency rTMS had better efficacy in promoting lower extremity motor function recovery than sham *** meta-analysis results of five randomized controlled trials demonstrated that highfrequency rTMS led to higher amplitudes of motor evoked potentials than low-frequency rTMS or sham *** findings suggest that rTMS can improve motor function in patients with stroke,and that low-frequency rTMS mainly affects motor function,whereas high-frequency rTMS increases the amplitudes of motor evoked *** highquality randomized controlled trials are needed to validate this *** work was registered in PROSPERO(registration ***42020147055)on April 28,2020.

关键词： cortical excitability lower extremity motor function network meta-analysis noninvasive brain stimulation stroke systematic review transcranial magnetic stimulation

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Identifying the limiting distribution by a general approach of Stein's method

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Science China Mathematics 2016年第12期59卷 2379-2392页

作者： SHAO qi-man ZHANG Zhuo-Song Department of Statistics The Chinese University of Hong Kong

A general exchange pair approach is developed to identify the limiting distribution for any sequence of random variables, by calculating the conditional mean and the conditional second moments. The error of approximation is also studied. In particular, a Berry-Esseen type bound of O(n^(-3/4)) is obtained for the Curie-Weiss model at the critical temperature.

关键词： Stein's method exchangeable pair limiting distribution Berry-Esseen bounds Curie-Weiss model

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On the Longest Length of Consecutive Integers

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Acta Mathematica Sinica,English Series 2011年第2期27卷 329-338页

作者： Min Zhi ZHAO qi-man SHAO Department of Mathematics Zhejiang University Hangzhou 310027 P. R. China Department of Mathematics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong P. R. China

Choose m numbers from the set {1,2,... ,n} at random without replacement. In this paper we first establish the limiting distribution of the longest length of consecutive integers and then apply the result to test rand... 详细信息

关键词： Sampling without replacement consecutive integers limit distribution test of randomness

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Self-normalization:Taming a wild population in a heavy-tailed world

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Applied Mathematics(A Journal of Chinese Universities) 2017年第3期32卷 253-269页

作者： SHAO qi-man ZHOU Wen-xin Department of Statistics The Chinese University of Hong Kong Department of Mathematics University of California

The past two decades have witnessed the active development of a rich probability theory of Studentized statistics or self-normalized processes, typified by Student’s t-statistic as introduced by W. S. Gosset more than a century ago, and their applications to statistical problems in high dimensions, including feature selection and ranking, large-scale multiple testing and sparse, high dimensional signal detection. many of these applications rely on the robustness property of Studentization/self-normalization against heavy-tailed sampling distributions. This paper gives an overview of the salient progress of self-normalized limit theory, from Student’s t-statistic to more general Studentized nonlinear statistics. Prototypical examples include Studentized one- and two-sample U-statistics. Furthermore, we go beyond independence and glimpse some very recent advances in self-normalized moderate deviations under dependence.

关键词： Berry-Esseen inequality Hotelling’s T 2-statistic large deviation moderate deviation self-normalization Student’s t-statistic U-statistic

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Numerical simulation of viscous flows with adaptively refined Cartesian grid

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航空动力学报 2014年第2期29卷 467-474页

作者： HAN Yu-qi gao Ge National Key Laboratory of Science and Technology on Aero-Engine Aero-thermodynamics School of Energy and Power EngineeringBeijing University of Aeronautics and Astronautics

Quadtree-based Cartesian grid was automatically generated from specified *** refinements were performed according to geometric parameters and solution of flow *** altered CCST(curvature corrected symmetry technique)approach was proposed to apply solid wall boundary conditions. Driven flows in a square cavity and flows around NACA0012airfoil were simulated and compared with the result of published structured grid and stretched Cartesian *** results show that solid wall boundary condition are accurately applied by current altered CCST approach,while incompressible/compressible subsonic, transonic and supersonic viscous flows are adequately simulated with adaptively refined Cartesian grid.

关键词： adaptively refined Cartesian grid viscous flow CCST(curvature corrected symmetry technique) boundary condition

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Multi-scale analysis on the pulverized coal flow behaviors under high,pressure dense-phase pneumatic conveying

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Particuology 2022年第1期20卷 107-114页

作者： Heming gao Xiaojuan Wang qi Chang School of Mechanical and Precision Instrument Engineering Xi'an University of TechnologyXi'an 710048China

To deeply knowledge of the flow behaviors of pulverized coal particles in dense gas-solid two-phase flow,a multi-scale analysis method based on electrostatic sensor array is applied for the multi-scale characterization of flow behaviors of dense gas-solid *** experimental results indicate that:for steady flow,with the increment of conveying pressure difference,the individual particles increase and the particle clusters decrease,the individual particle distribution is always inhomogeneous but the particle cluster distribution tends to be more homogeneous over the cross-section of pipe,while the average flow behavior of pulverized coal particles is always in the relatively static *** unsteady flow,the average flow behavior of pulverized coal particles is dynamic,and the flow behaviors of the multi-scale flow structures over the cross-section of pipe are all significantly ***,the effect of particle size on flow behavior of pulverized coal is also investigated and validated.

关键词： Dense-phase pneumatic conveying Pulverized coal Multi-scale Particle charging

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A triple-exposure color PIV technique for pressure reconstruction

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Science China(Technological Sciences) 2017年第1期60卷 1-15页

作者： WANG ZhongYi gao qi WANG JinJun Key Laboratory of Fluid Mechanics Ministry of Education Beijing University of Aeronautics and Astronautics Beijing 100191 China

The study developed a triple-exposure color particle image velocimetry(TE-CPIV) technique associated with pressure reconstruction, and validated its feasibility. A light source with the three primary colors of red, green, and blue(R, G, and B) is produced in a time sequence by a liquid crystal display(LCD) projector. Particle images at three different instants under the color illuminations are captured in one snapshot using a color digital single-lens reflex(SLR) camera with a complementary metal-oxide semiconductor(CMOS) sensor. A contamination correction algorithm based on a specific calibration is performed on the different color layers(R layer, G layer, and B layer) of the raw color image to reduce the contaminated intensity of each color illumination on the other two color layers. The corrected intensity generates three new color layers, from which a standard cross-correlation process in the classical PIV method is used to obtain two velocity fields. Eventually, an instantaneous pressure field is reconstructed from the two velocity fields. The feasibility of TE-CPIV was tested by two experiments with a solid body rotation flow and a cylinder wake flow. The results show acceptable accuracy and robustness of the new technique. The idea of the TE-CPIV is believed to provide a simple and effective way of estimating a pressure field with low cost and high convenience.

关键词： triple exposures color PIV pressure reconstruction

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Cognition-Based Interactive Phases and Strategies in Teaching Academic Reading

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Journal of Electronic Science and Technology 2017年第1期15卷 33-40页

作者： Zhao gao Shan gao qi Yang School of Foreign Languages University of Electronic Science and TechnologyChengdu 610054China

Academic English reading requires deeper cognitive involvement in addition to language proficiency and plays a vital role in moulding a critical mindset. However, cognitive progress is seldom targeted in classroom teaching. This study proposed a teaching method of three reading phases in terms of cognitive mechanism and communicative teaching *** university freshmen of non-English major participated in the study, who were taking the course of Academic English Reading in the 2nd semester. The data were collected from self-report Research Skills Assessment twice and semi-structured interview, and analyzed with paired sample t test and Pearson correlation. The results showed that 1） “critical thinking”, “organizing ideas”, and “finding information” were believed to improve significantly at the end of the course; 2） reading skill was associated with writing skill and the sense of “big picture” in self perception; 3） the cognition-based interactive reading instruction was acknowledged to be conducive to academic reading. It complements Academic English reading pedagogy by juxtaposing the need for both individual cognition and group interaction in classroom teaching.

关键词： Reading classroom skill proficiency interview thinking acknowledged instruction comprehension cognition

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