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PIV EXPERIMENTAL RESEARCH OF FLOW STRUCTURE IN RECTANGULAR CHANNEL WITH TRANSVERSELY PLACED SPIRAL COIL INSERT

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Journal of Hydrodynamics 2012年第4期24卷 518-525页

作者： TANG yu-feng TIAN Mao-cheng ZHANG guan-min School of Energy Source and Power Engineering Shandong UniversityJinan 250061China

The flow field in a rectangular channel with a transversely placed spiral coil insert is investigated by Particle Image Velocimetry （PIV） measurements in both transverse and longitudinal sections. The experimental results show that multi-longitudinal vortices are induced downstream of the spiral coil and are distributed as a symmetrical vortex array along the horizontal central line of the transverse section. Along the mainstream, due to the spiral motion of the longitudinal vortices, the velocity fluctuates in a manner of the damped sinusoidal curve and the velocity component in the wall normal direction is improved in the channel. Com- pared with the flow field in a smooth channel it is found that the movement of the longitudinal vortices can cause a continuous dis- turbance near the channel walls and thus enhances the fluid velocity in the near wall region, which consequently leads to the redu- ction of the velocity gradient and a more uniform velocity distribution. With the increase of the Reynolds number, the induced longitudinal vortices gain strength and become straighter and closer to the channel walls, thus the turbulence intensity is further enha- nced in this area.

关键词： Particle Image Velocimetry (PIV) spiral coil longitudinal vortices flow disturbance

Response Solutions for Degenerate Reversible Harmonic Oscillators with Zero-average Perturbation

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Acta Mathematica Sinica,English Series 2023年第10期39卷 2006-2030页

作者： Xin yu guan Jian Guo SI Wen SI School of Statistics and Mathematics Shandong University of Finance and EconomicsJi’nan 250002P.R.China School of Mathematics Shandong UniversityJi’nan 250100P.R.China

In this paper,we consider a class of normally degenerate quasi-periodically forced reversible systems,obtained as perturbations of a set of harmonic oscillators,{x˙=y+∈f1(ωt,x,y),y˙=λx^(l)+∈f2(ωt,x,y),where 0≠λ∈R,l>1 is an integer and the corresponding involution G is(−θ,x,−y)→(θ,x,y).The existence of response solutions of the above reversible systems has already been proved in[22]if[f2(ωt,0,0)]satisfies some non-zero average conditions(See the condition(H)in[22]),here[·]denotes the average of a continuous function on T^(d).However,discussing the existence of response solutions for the above systems encounters difficulties when[f_(2)(ωt,0,0)]=0,due to a degenerate implicit function must be *** article will be doing work in this *** purpose of this paper is to consider the case where[f2(ωt,0,0)]=*** precisely,with 2p˜0(seeλ˜in(2.2))and sufficiently small,response solutions exist for eachωsatisfying a weak non-resonant condition;(2)Forλ0 and l−p is even,we prove the system admits no response solutions in most regions.

关键词： Degenerate harmonic oscillators zero-average perturbation KAM theory reversible system response solutions

Iterative Phase Noise Suppression for Full-Duplex Communication Systems

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China Communications 2023年第2期20卷 226-234页

作者： Pengxin guan Yiru Wang Hongkang yu yuping Zhao School of Electronics Engineering and Computer Science Peking UniversityBeijing 100871China Wireless Product Research and Development Institute ZTE CorporationShenzhen 518057China

Oscillator phase noise is one of the bottlenecks that limits the self-interference(SI)cancellation capability of full-duplex *** this paper,we propose a method for the suppression of common phase error(CPE)and intercarrier interference(ICI)induced by the phase noise in full-duplex orthogonal frequency division multiplexing(OFDM)***,we regard the effect of CPE as a portion of the SI channel and perform estimation,reconstruction and elimination in the time ***,the ICI signal is estimated and suppressed in the frequency ***,by analysing the performance of proposed algorithm,we further develop an iterative mechanism to reduce the parameter estimation error and improve SI cancellation *** results show that the proposed method has a significant SI cancellation capability improvement over the traditional SI cancellation schemes.

关键词： full-duplex self-interference phase noise suppression

Elastic buckling analysis and optimization of thin-walled bamboo-like pipe beam subjected to pure bending

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Chinese Journal of Aeronautics 2024年第3期37卷 133-152页

作者： Yayun yu Dongli MA Liang ZHANG Xiaopeng YANG Hao guan School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China

In this paper,a stiffening design imitating the bamboo node is proposed for weight reduction of the long composite pipe beam subjected to bending *** distribution of bamboo nodes can efficiently suppress the ovalization of the section,thus significantly improving the bending resistance of the *** on this principle,ring stiffeners are proposed to be fixed to the pipe beam,making the long beam equivalent to the combination of a series of short pipes that suffered less section ovalization.A database of the optimal laminate orientations for different normalized lengths is obtained through optimizations,where the discreteness of the ply count is *** on this database,weight optimizations are conducted,and the optimal designs of beams with and without stiffeners are obtained and *** comparison results show that the proposed bamboo-like stiffened beam not only regains a near-linear load–displacement relationship,but also reduces the weight by up to 16%under the same buckling *** addition,it is found that for the pipe beams with radius-to-thickness ratios of more than 18,increasing the radius leads to a decrease in elastic buckling resistance when the weight remains a constant,which is opposite to the design for strength and *** model and database developed in this paper can provide a reference for weight reduction design and weight estimation for composite pipe beams.

关键词： Composite beam Buckling Thin-walled structure Unmanned aerial vehicles Bamboo

Microstructural evolution and strengthening mechanism of Al–Mg alloys with fine grains processed by accumulative continuous extrusion forming

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Journal of Materials Science & Technology 2022年第33期128卷 195-204页

作者： Bowei Yang yu Wang Minqiang Gao Changfeng Wang Renguo guan School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Key Laboratory of Near-Net Forming of Light Metals of Liaoning Province Dalian Jiaotong UniversityDalian 116028China Engineering Research Center of Continuous Extrusion Ministry of EducationDalian Jiaotong UniversityDalian 116028China

In this work,the mechanical properties and strengthening mechanisms induced by microstructural evolution in a rheo-extruded 5087 alloy processed via accumulative continuous extrusion forming(ACEF)were *** back-scattered diffraction(EBSD)and transmission electron microscopy(TEM)were utilized to characterize the microstructure of the alloy subjected to ACEF with various *** grain refinement caused by continuous dynamic recrystallization(CDRX)was *** results demonstrated that after 3 passes of ACEF,there was a significant grain refinement effect on the alloy,and the average grain size decreased from 45.6μm to 2.5μm;the ultimate tensile strength(UTS)and yield strength(YS)of the alloy increased to 362.8 MPa and 234.6 MPa,*** cells/walls generated during deformation promoted the formation of low angle grain boundaries(LAGBs).The accumulative strain accelerated the transformation of LAGBs to high angle grain boundaries(HAGBs).Dislocation pile-up enhanced the driving force of CDRX,and nano-sized Al_6(Mn,Fe)phases at the grain boundaries inhibited the growth of grains due to the pinning *** on the quantitative estimation,dislocation strengthening and grain boundary strengthening dominated the enhancement in YS of the ACEFed alloy.

关键词： Al-Mg alloy Grain refinement Mechanical property Dynamic recrystallization Strengthening mechanism

关注学习路上的慢跑者——苏霍姆林斯基“学困生”教育思想及启示

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兵团教育学院学报 2025年第1期35卷 56-64页

作者：王福关满姗翟玉洁石河子大学师范学院/兵团教育学院新疆石河子832003 石河子大学师范学院新疆石河子832003

苏霍姆林斯基在长期的教育实践中,形成了其独特的学困生教育观。本研究基于苏霍姆林斯基关于学困生的教育思想,主要从学校教育和家庭教育两方面分析了学困生的成因,并提出了相应的转化策略。苏霍姆林斯基的教育思想对当下学困生教育有... 详细信息

苏霍姆林斯基在长期的教育实践中,形成了其独特的学困生教育观。本研究基于苏霍姆林斯基关于学困生的教育思想,主要从学校教育和家庭教育两方面分析了学困生的成因,并提出了相应的转化策略。苏霍姆林斯基的教育思想对当下学困生教育有着重要启示,应让学生养成良好的学习习惯和学习的自觉性,构建学校的全面育人系统,强化教师的主导作用,引导学困生发挥自我转化的主体作用。

关键词：学困生苏霍姆林斯基转化策略启示

Radar fast long-time coherent integration via TR-SKT and robust sparse FRFT

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Journal of Systems Engineering and Electronics 2023年第5期34卷 1116-1129页

作者： CHEN Xiaolong guan Jian ZHENG Jibin ZHANG yue yu Xiaohan Naval Aviation University Yantai 264001China National Laboratory of Radar Signal Processing Xidian UniversityXi’an 710071China School of Electronic and Communication Engineering Sun Yat-Sen UniversityGuangzhou 510000China Unit 91977 of the PLA Beijing 100036China

Long-time coherent integration(LTCI)is an effective way for radar maneuvering target detection,but it faces the problem of a large number of search parameters and large amount of *** the simultaneous compensation of the range and Doppler migrations in complex clutter back-ground,and at the same time improving the calculation efficiency has become an urgent problem to be *** sparse transformation theory is introduced to LTCI in this paper,and a non-parametric searching sparse LTCI(SLTCI)based maneuvering target detection method is *** method performs time reversal(TR)and second-order Keystone transform(SKT)in the range frequency&slow-time data to complete high-order range walk compensation,and achieves the coherent integra-tion of maneuvering target across range and Doppler units via the robust sparse fractional Fourier transform(RSFRFT).It can compensate for the nonlinear range migration caused by high-order motion.S-band and X-band radar data measured in sea clutter background are used to verify the detection performance of the proposed method,which can achieve better detection performance of maneuvering targets with less computational burden compared with several popular integration methods.

关键词： radar maneuvering target detection sea clutter long-time coherent integration(LTCI) sparse transformation time reversal(TR) second-order Keystone transform(SKT)

Deep Learning Blockchain Integration Framework for Ureteropelvic Junction Obstruction Diagnosis Using Ultrasound Images

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Tsinghua Science and Technology 2024年第1期29卷 1-12页

作者： yu guan Pengceng Wen Jianqiang Li Jinli Zhang Xianghui Xie Faculty of Information Technology Beijing University of TechnologyBeijing 100124China Beijing Children’s Hospital Affiliated to Capital Medical University Beijing 100020China

UreteroPelvic Junction Obstruction(UPJO)is a common hydronephrosis disease in children that can result in an even progressive loss of renal *** is an economical,radiationless,noninvasive,and high noise preliminary diagnostic step for *** intelligence has been widely applied to medical fields and can greatly assist doctors'diagnostic *** demand for a highly secure network environment in transferring electronic medical data online,therefore,has led to the development of blockchain *** this study,we built and tested a framework that integrates a deep learning diagnosis model with blockchain *** diagnosis model is a combination of an attention-based pyramid semantic segmentation network and a discrete wavelet transformation-processed residual classification *** also compared the performance between benchmark models and our *** diagnosis model outperformed benchmarks on the segmentation task and classification task with MloU=87.93,MPA=93.52,and accuracy=91.77%.For the blockchain system,we applied the InterPlanetary File System protocol to build a secure and private sharing *** framework can automatically grade the severity of UPJO using ultrasound images,guarantee secure medical data sharing,assist in doctors'diagnostic ability,relieve patients'burden,and provide technical support for future federated learning and linkage of the Internet of Medical Things(loMT).

关键词： data mining image processing and computer vision machine learning medical information systems

Two-dimensional capillaries assembled by van der Waals heterostructures

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Nano Research 2023年第3期16卷 4119-4129页

作者： Jiaojiao Ma Kaiwen guan yu Jiang Yang Cao Sheng Hu State Key Laboratory of Physical Chemistry of Solid Surfaces Collaborative Innovation Center of Chemistry for Energy Materials(iChEM)College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Innovation Laboratory for Sciences and Technologies of Energy Materials of Fujian Province(IKKEM) Xiamen 361005China Pen-Tung Sah Institute of Micro-Nano Science and Technology Xiamen UniversityXiamen 361005China

Research on two-dimensional materials in the past decades has brought many insights of low-dimensional science on a wide range of related *** a novel two-dimensional structure,the atomic-scale capillaries which can conceptually be seen as the empty space left by removing few layers of two-dimensional materials from their bulk van der Waals crystals offer a unique platform of investigating physical and chemical processes of ions,molecules,and atoms under two-dimensional *** of many important problems,such as capillary condensation and water network structure that are difficult to be explored experimentally in other confinement structures,has now been accessible;two-dimensional migration of ions,water,and gases shows abnormal transport properties beyond conventional theory prediction;influence of quantum effect to molecule permeation is observable even at room *** these discoveries greatly extend our fundamental understandings of nano-science,and stimulate the development of potential *** review the fabrication of these two-dimensional capillaries which are created by the assembly of van der Waals heterostructures,and discuss the ultimate steric effects in the smallest possible *** interactions between capillary interior and confined particles are also *** coupled with external stimuli,these channels exhibit tunable mass transport behaviors,which not only gives feedback to the mechanism understanding but in turn guides the channel structure optimization.

关键词： atomic-scale capillaries van der Waals heterostructures two-dimensional materials smallest confinement mass transport