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HEAVY BALL FLEXIBLE GMRES METHOD FOR NONSYMMETRIC LINEAR SYSTEMS

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Journal of Computational Mathematics 2022年第5期40卷 711-727页

作者： mei Yang ren-Cang Li School of Mathematical Sciences Shanghai Jiao Tong UniversityShanghai 200240China Department of Mathematics University of Texas at ArlingtonArlingtonTXUSA

Flexible GMRES(FGMRES)is a variant of preconditioned GMRES,which changes preconditioners at every Arnoldi *** often has to be restarted in order to save storage and reduce orthogonalization cost in the Arnoldi *** restarted GMRES,FGMRES may also have to be restarted for the same reason.A major disadvantage of restarting is the loss of convergence *** this paper,we present a heavy ball flexible GMRES method,aiming to recoup some of the loss in convergence speed in the restarted flexible GMRES while keep the benefit of limiting memory usage and controlling orthogonalization *** tests often demonstrate superior performance of the proposed heavy ball FGMRES to the restarted FGMRES.

关键词： GMRES Flexible GMRES Heavy ball GMRES Preconditioner Linear system.

基于移动可穿戴设备数据源的多中心医院药师工作强度和压力现状调查

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中国医院药学杂志 2017年第23期37卷 2400-2404页

作者：王婷唐洪梅蔡庆群刘韬区炳雄王若伦伍俊妍任结梅黄伟强肖焕钟艺李磊广州中医药大学广东广州510405 广州中医药大学第一附属医院广东广州510405 中山大学肿瘤防治中心广东广州510060 广东省中医院广东广州510120 广州医科大学附属第二医院广东广州510260 中山大学第二附属医院广东广州510120

目的:调查广州市5家三甲医院门诊调剂药师的工作强度和压力,为改善药师生活质量,提高工作效率和服务水平提供依据。方法:随机入组广州市5家三级甲等医院60位门诊西药房调剂药师,采用可携带实时量化工具采集药师岗位的日行走步数,调剂岗... 详细信息

目的:调查广州市5家三甲医院门诊调剂药师的工作强度和压力,为改善药师生活质量,提高工作效率和服务水平提供依据。方法:随机入组广州市5家三级甲等医院60位门诊西药房调剂药师,采用可携带实时量化工具采集药师岗位的日行走步数,调剂岗位日步行时间、以及调剂和发药药品条目数,在线完成MBI-GS职业倦怠量表和药师压力源问卷调查。用SPSS软件对数据进行整理和分析。结果:79.7%药师岗位日步数超过10 000步,42.4%药师超过15 000步,10.2%药师超过20 000步,均远远超过全国人均日步数(5 112步),且超过2016年步数最多的快递员群体人均日步数(8 803步)。调剂药师每日至少行走4 h,当排班到急诊、直落或者夜班时,药师需行走7 h。不同性别、年龄、职称和工作经验的药师职业倦怠各因素得分和总分均无统计学差异;不同学历的药师在情感衰竭和个人成就感方面的得分无统计学差异;但在去人性化得分方面,专科学历药师得分最高,且倦怠总分也最高(P<0.01)。81.36%药师工作压力在中等以上,其中工作压力高占22.03%,工作压力非常高占6.78%。被调查者中,40.98%对患者纪律感到压力,31.15%工作强度感到压力,8.20%对职称待遇感到压力,18.03%问责机制感到压力,只有1.64%无工作压力。结论:门诊调剂药师存在工作强度高、压力大的问题,应当引起管理者重视。

关键词：门诊调剂药师工作强度工作压力可携带实时量化工具可穿戴设备

Floquet analysis of fundamental,subharmonic and detuned secondary instabilities of Grtler vortices

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Science China(Physics,Mechanics & Astronomy) 2014年第3期57卷 555-561页

作者： ren jie FU Song School of Aerospace Engineering Tsinghua University

Nonlinear parabolized stability equations are employed in this work to investigate the nonlinear development of the G6rtler insta- bility up to the saturation stage. The perturbed boundary layer is highly inflectional both in the normalwise and spanwise directions and receptive to the secondary instabilities. The Floquet theory is applied to solve the fundamental, subharmonic and detuned secondary instabilities. With the Gortler-vortices-distorted base flow, two classes of secondary disturbances, i.e. odd modes and even modes, are identified according to the eigenfunctions of the disturbances. These modes may result in different patterns in the late stages of the transition process. Li and Malik [ 1 ] have shown the sinuous and varicose types of breakdown originating from the odd and even modes. The current study focuses on the four most amplified modes termed the even modes I ＆ Ⅱ and odd modes I ＆ lI. Odd mode II was missing in the work of Li and Malik [1] probably due to their inviscid simplifeation. The detuned modes are confirmed to be less amplifed than the fundamental （for the odd mode I） and subharmonic modes （for even modes I ＆ II and the odd mode II）.

关键词： Goirtler vortices secondary instability Floquet theory

Competition of the multiple Grtler modes in hypersonic boundary layer flows

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Science China(Physics,Mechanics & Astronomy) 2014年第6期57卷 1178-1193页

作者： ren jie FU Song School of Aerospace Engineering Tsinghua University

Competition of multiple Gortler modes in hypersonic boundary layer flows are investigated with the local and marching methods. The wall-layer mode （mode W） and the trapped-layer mode （mode T） both occur in the compressible boundary layer where there exists a temperature adjustment layer near the upper edge. The mode T has the largest growth rate at a lower Gortler number while the mode W dominates at larger G/Srtler numbers. These two modes are both responsible for the flow transition in the hypersonic flows especially when Gortler number is in the high value range in which the crossover of these two modes takes place. Such high Gortler numbers are virtually far beyond the neutral regime. The nonparallel base flows, therefore, cease to influence the stability behavior of the Gortler modes. The effects of the Mach number on the multiple Gortler modes are studied within a chosen Mach number of 0.95, 2, 4 and 6. When the flow Mach number is sufficiently large, e.g., Ma ≥4, the growth rate crossover of the mode T and mode W occurs both in the conventional G-β map as well as on the route downstream for a fixed wavelength disturbance. Four particular regions （Region T, T-W, W-T and W） around the crossover point are highlighted with the marching analysis and the result matches that of the local analysis. The initial disturbance of a normal mode maintains the shape in its corresponding dominating region while a shape-transformation occurs outside this region.

关键词： Gortler vortices linear stability theory multiple modes local analysis marching analysis

A Special Two-Soliton Solution of sine-Gordon Equation

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Communications in Theoretical Physics 2005年第1期43卷 9-12页

作者： AOSheng-mei YANJia-ren DepartmentofPhysics HunanNormalUniversityChangsha410081China

A special two-soliton solution of sine-Gordon equation is obtained by using the Hirota direct method. It is shown in a mass-centre system how two kinks move and interact with each other.

关键词： soliton sine-Gordon equation Hirota direct method kink

Comparative permeability of three saikosaponins and corresponding saikogenins in Caco-2 model by a validated UHPLC-MS/MS method

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Journal of Pharmaceutical Analysis 2021年第4期11卷 435-443页

作者： Siqi ren Jingjing Liu Yunwen Xue mei Zhang Qiwei Liu jie Xu Zunjian Zhang Rui Song Key Laboratory of Drug Quality Control and Pharmacovigilance China Pharmaceutical UniversityNanjing210009China State Key Laboratory of Natural Medicine China Pharmaceutical UniversityNanjing210009China

Saikosaponins(SSs)are the main active components extracted from Bupleuri Radix(BR)which has been used as an important herbal drug in Asian countries for thousands of *** has been reported that the intestinal bacteria plays an important role in the in vivo disposal of oral *** the deglycosylated derivatives(saikogenins,SGs)of SSs metabolized by the intestinal bacteria are speculated to be the main components absorbed into the blood after oral administration of SSs,no studies have been reported on the characteristics of SGs for their intestinal absorption,and those for SSs are also ***,a rapid UHPLC-MS/MS method was developed to investigate and compare the apparent permeability of three common SSs(SSa,SSd,SSb2)and their corresponding SGs(SGF,SGG,SGD)through a bidirectional transport experiment on Caco-2 cell monolayer *** method was validated according to the latest FDA guidelines and applied to quantify the six analytes in transport medium samples extracted via liquid-liquid extraction(LLE).The apparent permeability coefficient(Papp)determined in this study indicated that the permeability of SGs improved to the moderate class compared to the corresponding parent compounds,predicting a higher in vivo ***,the efflux ratio(ER)value demonstrated an active uptake of SSd and the three SGs,while a passive diffusion of SSa and SSb2.

关键词： Bupleuri Radix Saikosaponin Saikogenin UHPLC-MS/MS Caco-2 cells Permeability

Study on the long-term performance of shield tunnel passing through the gas-bearing strata

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Underground Space 2023年第2期9卷 1-19页

作者： jie He Xiangyang Wei mei Yin College of Civil Engineering Tongji UniversityShanghai 200092China State Key Laboratory for Disaster Reduction in Civil Engineering Tongji UniversityShanghai 200092China Key Laboratory of Geotechnical and Underground Engineering of Ministry of Education Tongji UniversityShanghai 200092China Civil and Environmental Engineering Department Brunel University LondonLondon UB83PHUK Recei

When the shield tunnel passes through the gas-bearing strata,gas and water leakage may occur depending on the sealing performance of the segment *** process involves the complex multiphase seepage flow phenomenon in unsaturated *** this study,a fully coupled solid-liquid-gas model of the GIL Utility Tunnel was established to investigate the influence of the high-pressure gas on the mechanical properties of the tunnel segments and *** constitutive model of the Extended Barcelona Basic Model was imple-mented to simulate the effect of the seepage process on soil *** results show that significant upward displacement occurred in the gas reservoir and its overlying strata,and the maximum displacement reached 30 *** addition,during the leakage of the gas and the water,an increase in the average soil effective stress was *** would induce a reduction in the suction and expansion of the yield *** tunnel tended to be stable from 20 years onwards,thus the soil deformation due to the water leakage only occurred at the early *** addition,the joint opening under the most unfavorable internal force combination was 0.69 mm,and the correspond-ing bolt stress was 119.5 MPa,which is below the yield *** results of this study help to understand the influence of high-pressure gas on tunnel safety and the sealing performance of the joints.

关键词： A coupled solid-liquid-gas model Unsaturated soil Multiphase seepage Gas-bearing strata Shield tunnel FEM

WALL EFFECTS ON FLOWS PAST TWO TANDEM CYLINDERS OF DIFFErenT DIAMETERS

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Journal of Hydrodynamics 2012年第1期24卷 1-10页

作者： JIANG ren-jie LIN Jian-zhong State Key Laboratory of Fluid Power Transmission and Control Zhejiang UniversityHangzhou 310027China China Jiliang University Hangzhou 310018China

Flows past two tandem cylinders of different diameters placed centrally in a channel with fixed centre-to-centre spacing 6D and diameter ratio are simulated based on the Lattice Boltzmann Method（LBM）.In all the simulations,the diameter of the smaller cylinder is chosen as the characteristic *** Reynolds number based on the average inflow velocity is 20-120 and studies are over the range of blockage ratio *** both Small-Big Arrangement（SBA）and Big-Small Arrangement（BSA）,the effects of the channel width and Reynolds number on the flow structures and force coefficients are *** show that the flows in BSA are more regular than those in SBA for the same flow *** BSA with and,the force coefficients all fluctuate with constant amplitudes and a coupled frequency,the coupled frequency becomes small as the blockage ratio decreases and by an exact test we give out the relation of the blockage ratio and Strouhal *** the blockage ratio decreases to 2,there exist pitchfork bifurcations in both SBA and BSA,and results show that the critical Reynolds numbers of pitchfork bifurcations for SBA and BSA are both between 60 and *** SBA with,the flow structure has a static asymmetric *** is found that the channel width has also an effect on the critical spacing where the flow changes from single body mode into co-shedding *** an accurate survey on flows past two cylinders with equal diameters placed inside a channel with the width,the relation between channel width and the critical spacing is given and results show that the critical spacing increases as the channel width increases.

关键词： two tandem cylinders different diameters blockage ratio critical spacing Lattice Boltzmann Method(LBM)

Output Feedback Stabilization of an Unstable Wave Equation with Observations Subject to Time Delay

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Journal of Systems Science & Complexity 2016年第1期29卷 99-118页

作者： YANG Kunyi ren Xiang ZHANG jie College of Science North China University of Technology

This paper focuses on boundary stabilization of a one-dimensional wave equation with an unstable boundary condition,in which observations are subject to arbitrary fixed time *** observability inequality indicates that the open-loop system is observable,based on which the observer and predictor are designed:The state of system is estimated with available observation and then predicted without *** that equivalently the authors transform the original system to the well-posed and exponentially stable system by backstepping *** equivalent system together with the design of observer and predictor give the estimated output *** is shown that the closed-loop system is exponentially *** simulations are presented to illustrate the effect of the stabilizing controller.

关键词： Exponential stability observability inequality output feedback unstable boundary condition time delay wave equation