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A Combination Model for Image Denoising

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Acta Mathematicae Applicatae Sinica 2016年第3期32卷 781-792页

作者： Yi-ping xu School of Science Southwest University of Science and Technology

In this paper, we propose an efficient combination model of the second-order ROF model and a simple fourth-order partial differential equation （PDE） for image denoising. The split Bregman method is used to convert the nonlinear combination model into a linear system in the outer iteration, and an algebraic multigrid method is applied to solve the linear system in the inner iteration. Furthermore, Krylov subspace acceleration is adopted to improve convergence in the outer iteration. At the same time, we prove that the model is strictly convex and exists a unique global minimizer. We have also conducted a variety of numerical experiments to analyze the parameter selection criteria and discuss the performance of ~he fourth-order PDE in the combination model. The results show that our model can reduce blocky effects and our algorithm is efficient and robust to solve the proposed model.

关键词： image denoising partial differential equations split Bregman method algebraic multi-grid method Krylov subspace acceleration

The Inversionless Amplification in a Tripod System of SrRb Atoms in a Magneto-optical Trap

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Chinese Physics Letters 2014年第4期31卷 33-36页

作者： SUN Zhen JIA Feng-Dong LV Shuang-Fei RUAN Ya-ping QING Bo xuE ping xu Xiang-yuan DAI Xing-Can ZHONG zhi-ping School of Physics University of Chinese Academy of Sciences Beijing 100049 State Key Laboratory of Low-dimensional Quantum Physics Department of PhysicsTsinghua University and Collaborative Innovation Center of Quantum M~tter Beijing 100084 Research Center of Laser Fusion China Academy of Engineering Physics Mianyang 621900 Department of Physics Capital Normal University Beijing 100037

The probe transmission spectra around the atomic transition 52S1/2,F = 2 → 52P3/2,F = 2 of 87Rb are measured in a magneto-optical trap by adding a coupling field around the atomic transition 52S1/2, F = 2 → 52 P3/2, F1 = 2. The inversionless amplification is observed in the spectrum over the atomic transition 5 2 S1/2, F = 2 → 52pa/2, Fr = 2. The tripod eleetromagnetically induced transparency is proposed to account for the ampli- fication feature, in which population distributions among these related atomic levels play an important role.

关键词： MAGNETOOPTICS ATOMIC transitions COUPLING reactions (Chemistry) AMPLIFICATION reactions ELECTROMAGNETIC interactions

PIV analysis and high-speed photographic observation of cavitating flow field behind circular multi-orifice plates

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Water Science and Engineering 2020年第2期13卷 145-153页

作者： zhi-ping Guo Xi-huan Sun zhi-yong Dong College of Hydro-Science and Engineering Taiyuan University of TechnologyTaiyuan 030024China Department of Transportation Engineering Shanxi Conservancy Technical InstituteYuncheng 044004China College of Civil Engineering and Architecture Zhejiang University of TechnologyHangzhou 310014China

Based on a self-developed hydrodynamic cavitation device with different geometric parameters for circular multi-orifice plates,turbulence characteristics of cavitating flow behind multi-orifice plates,including the effects of orifice number and orifice layout on longitudinal velocity,turbulence intensity,and Reynolds stress,were measured with the particle image velocimetry(PIV)*** regimes of the cavitating flow were also observed with high-speed *** experimental results showed the following:(1)high-velocity multiple cavitating jets occurred behind the multi-orifice plates,and the cavitating flow fields were characterized by topological structures;(2)the longitudinal velocity at each cross-section exhibited a sawtooth-like distribution close to the multi-orifice plate,and each sawtooth indicated one jet issuing from one orifice;(3)there were similar magnitudes and forms for the longitudinal and vertical turbulence intensities at the same cross-section;(4)the variation in amplitude of Reynolds stress increased with an increase in orifice number;and(5)the cavitation clouds in the flow fields became denser with the increase in orifice number,and the clouds generated by the staggered layout of orifices were greater in number than those generated by the checkerboard-type one for the same orifice *** experimental results can be used to analyze the mechanism of killing pathogenic microorganisms through hydrodynamic cavitation.

关键词： Cavitating flow Circular multi-orifice plate PIV technique High-speed photography Turbulence characteristics

Hierarchical Management Scheme by Local Fields

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Acta Mathematica Sinica,English Series 2011年第1期27卷 155-168页

作者： zhi Hong YUE Mao zhi xu School of Mathematical Sciences Peking University Beijing 100871 P. R. China Key Laboratory of Network and Software Security Assurance School of Mathematical Sciences Peking University Beijing 100871 P. R. China

In the present paper we propose a new hierarchical management scheme within suitable extensions of 2-adic numbers, in which the subfields are treated as classes, and the communications are realized by computation on elliptic curves. The security of our system is much stronger than that of the traditional public key cryptographic systems.

关键词： Hierarchical management local fields elliptic curves

Numerical study on roll dynamics of damaged ship in beam waves and calm water

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Journal of Hydrodynamics 2023年第3期35卷 482-497页

作者： zhi-yun Huang zhi-liang Gao Sang-ming xu Key Laboratory of High Performance Ship Technology Ministry of Education Wuhan University of TechnologyWuhan 430063China Wuhan University of Technology College of Marine and Energy Power EngineeringWuhan 430063China Union Strong(Beijing)Technology Co. LtdBeijing 100176China

Computational fluid dynamics is used to study the roll dynamics of a damaged ship in beam waves with various steepnesses and in calm *** wave-making method,which combines the velocity-inlet boundary and momentum source with the fifth-order Stokes theory,is employed for wave *** SST k-ωturbulence model with a modification to the turbulent viscosity in Reynolds stress is adopted to prevent the over-production of turbulence in the numerical wave *** lateral drift restrained model with a combined dynamic mesh strategy is utilized to deal with the coupled heave-sway-roll motions of the ***,benchmarking tests are performed,including wave generation and roll response of the damaged ship in regular beam ***,the effects of incident wave steepness on the roll response of the damaged ship are *** different wave steepnesses,the ship roll motion is dominated by the first-order harmonic *** second-order component increases with the increase of wave ***,the roll hydrodynamic coefficients for different parts of the damaged ship are investigated with different rolling *** added moment of inertia for the whole damaged ship is mainly attributed to the external hull composition and changes slightly with the change of roll amplitude and *** added moment of inertia for the compartments could be negative in particular *** damping coefficients of the whole damaged ship and external hull increase with the increase of roll amplitude and frequency,while that of the compartments appears complicated with the change of roll amplitude and frequency.

关键词： Damaged ship roll dynamics wave steepness hydrodynamic coefficients computational fluid dynamics(CFD)

A Novel Series of Refractory High-Entropy Alloys Ti2ZrHf0.5VNbx with High Specific Yield Strength and Good Ductility

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 925-931页

作者： Dong-xu Qiao Hui Jiang Wen-Na Jiao Yi-ping Lu zhi-Qiang Cao Ting-Ju Li Key Laboratory of Solidification Control and Digital Preparation Technology(Liaoning Province) School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China College of Mechanical and Electronic Engineering Shandong University of Science and TechnologyQingdao 266590China

A series of Ti2ZrHf0.5VNbx( x = 0, 0.25, 0.5, 0.75 and 1.0) refractory high-entropy alloys were prepared to investigate the alloying effect of Nb on the microstructures and mechanical *** the alloys displayed a simple BCC *** microstructures of the alloys changed from the initial single-phase columnar structure( x = 0) to dendrite microstructure( x > 0).At room temperature, all the alloys exhibited high ductility(with the compressive strains of more than 50%).With the increase in Nb content, the yield strength slightly decreased from 1160 to 980 MPa and the hardness dropped from 338 to 310 ***, the alloys exhibited low density from 6.47 to 6.84 g/cm3 and high specific yield strength(SYS) from 143 to 179 kPa m3/*** comprehensive performance of ductility and SYS was superior to most of the reported highentropy *** yield strength of the alloys increased from 405 to 859 MPa and from 85 to 195 MPa with the addition of Nb element at 873 K and 1073 K, respectively.

关键词： Specific yield strength Refractory metals Structure Mechanical properties

Numerical investigation of the effects of aquatic plants on wind-induced currents in Taihu Lake in China

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Journal of Hydrodynamics 2019年第4期31卷 778-787页

作者： Tian-ping xu Ming-liang Zhang Hcng-zhi Jiang Jun Tang Hong-xing Zhang Hui-ting Qiao School of Ocean Science and Environment Dalian Ocean University Dalian 116023 China National Marine Environmental Monitoring Center Dalian 116023 China State Key Laboratory of Coastal and Offshore Engineering Dalian University of Technology Dalian 116023 China

Shallow lakes are an important part of the earth's water circulation system, and many factors may impact the evolution of the lake water circulation, including the wind, the topography, the human activities, and the aquatic plants. This paper proposes a depth-averaged 2-D hydrodynamic model to investigate the interaction of the wind-induced current and the aquatic plant in the lake. The model is based on the generalized shallow water equations solved by an explicit finite volume method with unstructured triangular grids. The drag force of the vegetation is considered into the momentum equations as the source term. Remote sensing techniques are applied to evaluate the aquatic vegetation in the Taihu Lake, China, based on Landsat TM satellite images. The study model is then used to simulate the characteristics of the wind-induced currents in the Taihu Lake, without and with the vegetation effects. The simulation results are in good agreement with the field measurements, demonstrating that the aquatic plants significantly affect the magnitude of the velocity and the flow circulation induced by the wind in the Taihu Lake. In addition, a sensitivity analysis reveals that the plant parameters (the density and the drag force coefficient) are significant factors influencing the velocity and the structure of the currents in the Taihu Lake.

关键词： Finite volume method Roe solver shallow lake wind-induced current aquatic plant

Thrombolysis and extracorporeal cardiopulmonary resuscitation for cardiac arrest due to pulmonary embolism:A case report

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World Journal of Critical Care Medicine 2025年第1期14卷 111-117页

作者： Guan-Xing Yuan zhi-ping Zhang Jia Zhou Department of Emergency Wuhan Asia General HospitalWuhan 430056Hubei ProvinceChina Department of Neurosurgery Central Theater Command General HospitalWuhan 430000Hubei ProvinceChina

BACKGROUND Cardiac arrest caused by acute pulmonary embolism(PE)is the most serious clinical circumstance,necessitating rapid identification,immediate cardiopulmonary resuscitation(CPR),and systemic thrombolytic *** CPR(ECPR)is typically employed as a rescue therapy for selected patients when conventional CPR is failing in settings where it can be *** SUMMARY We present a case of a 69-year-old male who experienced a prolonged cardiac arrest in an ambulance with pulseless electrical *** arrival at the emergency department with ongoing manual chest compressions,bedside pointof-care ultrasound revealed an enlarged right ventricle without *** PE was suspected as the cause of cardiac arrest,and intravenous thrombolytic therapy with 50 mg tissue plasminogen activator was administered during mechanical chest *** 31 minutes of CPR,return of spontaneous circulation was not achieved until 8 minutes after initiation of Veno-arterial extracorporeal membrane oxygenation(ECMO)*** ECMO support,the hemodynamic status and myocardial contractility significantly ***,the patient ultimately did not survive due to intracerebral hemorrhagic complications,leading to death a few days later in the *** This case illustrates the potential of combining systemic thrombolysis with ECPR for refractory cardiac arrest caused by acute PE,but it also highlights the increased risk of significant bleeding complications,including fatal intracranial hemorrhage.

关键词： Pulmonary embolism Cardiac arrest Thrombolytic therapy Cardiopulmonary resuscitation Extracorporeal membrane oxygenation Intracranial hemorrhage Case report

A Series of Variable Separation Solutions and New Soliton Structures of （2＋1）-Dimensional Korteweg-de Vries Equation

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Communications in Theoretical Physics 2006年第3X期46卷 403-406页

作者： xu Chang-zhi Department of Physics Jinhua Education College Jinhua 321000 China

Variable separation approach is introduced to solve the （2＋1）-dimensional KdV equation. A series of variable separation solutions is derived with arbitrary functions in system. We present a new soliton excitation model （24）. Based on this excitation, new soliton structures such as the multi-lump soliton and periodic soliton are revealed by selecting the arbitrary function appropriately.

关键词： variable separation approach (2+1)-dimensional KdV equation new soliton excitation