检索结果-南通市图书馆

Natural vibration and critical velocity of translating Timoshenko beam with non-homogeneous boundaries

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1523-1538页

作者： Yanan LI jieyu ding Hu ding Liqun CHEN Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Frontier Science Center of MechanoinformaticsSchool of Mechanics and Engineering Science Shanghai University School of Mathematics and Statistics Qingdao University

In most practical engineering applications, the translating belt wraps around two fixed wheels. The boundary conditions of the dynamic model are typically specified as simply supported or fixed boundaries. In this paper, non-homogeneous boundaries are introduced by the support wheels. Utilizing the translating belt as the mechanical prototype, the vibration characteristics of translating Timoshenko beam models with nonhomogeneous boundaries are investigated for the first time. The governing equations of Timoshenko beam are deduced by employing the generalized Hamilton's principle. The effects of parameters such as the radius of wheel and the length of belt on vibration characteristics including the equilibrium deformations, critical velocities, natural frequencies,and modes, are numerically calculated and analyzed. The numerical results indicate that the beam experiences deformation characterized by varying curvatures near the *** radii of the wheels play a pivotal role in determining the change in trend of the relative difference between two beam models. Comparing the results unearths that the relative difference in equilibrium deformations between the two beam models is more pronounced with smaller-sized wheels. When the two wheels are of equal size, the critical velocities of both beam models reach their respective minima. In addition, the relative difference in natural frequencies between the two beam models exhibits nonlinear variation and can easily exceed 50%. Furthermore, as the axial velocities increase, the impact of non-homogeneous boundaries on modal shape of translating beam becomes more significant. Although dealing with non-homogeneous boundaries is challenging, beam models with non-homogeneous boundaries are more sensitive to parameters, and the differences between the two types of beams undergo some interesting variations under the influence of non-homogeneous boundaries.

关键词：

右美托咪定联合氯普鲁卡因在剖宫产硬膜外麻醉中的应用效果

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

中国基层医药 2024年第3期31卷 412-416页

作者：刘俊涛王岩丁洁羽金华市人民医院麻醉科金华321000

目的探讨右美托咪定联合氯普鲁卡因在剖宫产硬膜外麻醉中的应用效果。方法采取前瞻性研究,选取2020年1月至2022年12月金华市人民医院麻醉科行剖宫产硬膜外麻醉产妇133例采用病例对照,按照随机数字表法分为罗哌卡因组(66例)与氯普鲁卡因... 详细信息

目的探讨右美托咪定联合氯普鲁卡因在剖宫产硬膜外麻醉中的应用效果。方法采取前瞻性研究,选取2020年1月至2022年12月金华市人民医院麻醉科行剖宫产硬膜外麻醉产妇133例采用病例对照,按照随机数字表法分为罗哌卡因组(66例)与氯普鲁卡因组(67例)。罗哌卡因组予以右美托咪定联合罗哌卡因麻醉,氯普鲁卡因组予以右美托咪定联合氯普鲁卡因麻醉。观察两组的麻醉效果(麻醉起效时间、麻醉持续时间、达峰效应时间)、血压变化(收缩压、舒张压)、不良反应(术中寒战、恶心呕吐、尿潴留、皮肤瘙痒、下肢麻木)以及肌松满意度。结果氯普鲁卡因组的麻醉起效时间、麻醉持续时间、达峰效应时间分别为(6.91±1.54)min、(61.54±5.31)min、(11.79±4.12)min,均短于罗哌卡因组的(9.65±1.92)min、(83.57±6.69)min、(18.32±4.81)min,差异均有统计学意义(t=9.08、21.05、8.41,均P<0.001);两组麻醉10 min、麻醉结束时的收缩压、舒张压均升高,但氯普鲁卡因组的升高幅度较小,两组的组间、时点间、组间·时点间交互作用比较,差异均有统计学意义(F=7.36,P<0.001;F=10.03,P<0.001;F=9.83,P<0.001与F=5.12,P=0.001;F=6.72,P<0.001;F=8.01,P<0.001);氯普鲁卡因组的不良反应发生率为4.48%(3/67),低于罗哌卡因组的15.15%(10/66),差异有统计学意义(χ^(2)=4.29,P<0.05);氯普鲁卡因组的肌松满意度为94.03%(63/66),高于罗哌卡因组的81.82%(54/66),差异有统计学意义(Z=5.73,P<0.05)。结论右美托咪定联合氯普鲁卡因在剖宫产硬膜外麻醉中的应用效果较好,可提高麻醉效果,稳定产妇血压,减少不良反应,且肌松满意度高,值得应用。

关键词：剖宫产术麻醉,硬膜外血压肌松弛药物相关性副作用和不良反应右美托咪定氯普鲁卡因罗哌卡因

Robust cross-modal retrieval with alignment refurbishment

在线全文

学校读者我要写书评

暂无评论

Frontiers of Information Technology & Electronic Engineering 2023年第10期24卷 1403-1415页

作者： Jinyi GUO jieyu ding School of Computer Science and Engineering Nanjing University of Science and TechnologyNanjing 210094China School of Mathematics and Statistics Qingdao UniversityQingdao 266071China

Cross-modal retrieval tries to achieve mutual retrieval between modalities by establishing consistent alignment for different modal ***,many cross-modal retrieval methods have been proposed and have achieved excellent results;however,these are trained with clean cross-modal pairs,which are semantically matched but costly,compared with easily available data with noise alignment(i.e.,paired but mismatched in semantics).When training these methods with noise-aligned data,the performance degrades ***,we propose a robust cross-modal retrieval with alignment refurbishment(RCAR),which significantly reduces the impact of noise on the ***,RCAR first conducts multi-task learning to slow down the overfitting to the noise to make data ***,RCAR uses a two-component beta-mixture model to divide them into clean and noise alignments and refurbishes the label according to the posterior probability of the noise-alignment *** addition,we define partial and complete noises in the noise-alignment *** results show that,compared with the popular cross-modal retrieval methods,RCAR achieves more robust performance with both types of noise.

关键词： Cross-modal retrieval Robust learning Alignment correction Beta-mixture model

地理信息低代码开发平台的编排设计和实现方法

在线全文

学校读者我要写书评

暂无评论

测绘地理信息 2024年第2期49卷 131-134页

作者：翁杰任福刘鹏程瑛李栩滨江河胡君丁婕玉武汉大学资源与环境科学学院湖北武汉430079 武汉浮木科技有限公司湖北武汉430223 武汉大学地理信息系统教育部重点实验室湖北武汉430079 自然资源部数字制图与国土信息应用重点实验室湖北武汉430079 武汉大学政治与公共管理学院湖北武汉430072

描述了一种基于浏览器/服务器(browser/server,B/S)架构的地理信息低代码开发平台的可视化编排设计和实现方法,为组件库、界面层编排、逻辑层编排和数据层编排设计了完善的行为规则。通过该方法实现平台的编排能力,采用拖拽组件和配置... 详细信息

描述了一种基于浏览器/服务器(browser/server,B/S)架构的地理信息低代码开发平台的可视化编排设计和实现方法,为组件库、界面层编排、逻辑层编排和数据层编排设计了完善的行为规则。通过该方法实现平台的编排能力,采用拖拽组件和配置参数、逻辑编排、数据编排等方式实现领域地理信息应用软件开发,并用实例证明了该方法能够大幅提高地理信息应用软件开发效率、减少开发成本。

关键词：低代码组件界面层编排逻辑层编排数据层编排

Optimization of multibody systems based on the generalized-α projection method for DAEs

在线全文

学校读者我要写书评

暂无评论

Theoretical & Applied Mechanics Letters 2012年第6期2卷 61-64页

作者： jieyu ding Zhenkuan Pan College of Information Engineering Qingdao University Qingdao 266071China

Efficient optimization strategy of multibody systems is developed in this paper. Aug- mented Lagrange method is used to transform constrained optimal problem into unconstrained form firstly. Then methods based on second order sensitivity are used to solve the unconstrained problem, where the sensitivity is solved by hybrid method. Generalized-α method and generalized-α projection method for the differential-algebraic equation, which shows more efficient properties with the lager time step, are presented to get state variables and adjoint variables during the optimization procedure. Numerical results validate the accuracy and efficiency of the methods is presented.

关键词： multibody system optimization augmented Lagrange method differential-algebraic equa-tions generalized-α method

Whittle’s Index Based Sensor Scheduling for Multiprocess Systems Under DoS Attacks

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science & Complexity 2024年第1期37卷 329-350页

作者： CAI Zai ding Kemi Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and TechnologyShenzhen 518055China.

In this paper,the authors consider how to design defensive countermeasures against DoS attacks for remote state estimation of multiprocess *** each system,a sensor will measure its state and transmits the data packets through an unreliable channel which is vulnerable to be jammed by an *** limited communication bandwidth,only a subset of sensors are allowed for data transmission,and how to select the optimal one to maximize the accuracy of remote state estimation is the focus of the proposed *** authors first formulate this problem as a Markov decision process and investigate the existence of optimal ***,the authors demonstrate the piecewise monotonicity structure of optimal *** the difficulty of obtaining an optimal policy of large-scale problems,the authors develop a suboptimal heuristic policy based on the aforementioned policy structure and Whittle’s ***,a closed form of the indices is derived in order to reduce implementation complexity of proposed scheduling policy and numerical examples are provided to illustrate the proposed developed results.

关键词： DoS attacks Kalman filter remote state estimation Whittle’s index.

A vertical track nonlinear energy sink

在线全文

学校读者我要写书评

暂无评论

Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 931-946页

作者： Meng LI Hu ding Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai 200444China

Eliminating the effects of gravity and designing nonlinear energy sinks(NESs)that suppress vibration in the vertical direction is a challenging task with numerous damping *** this paper,the dynamic design of a vertical track nonlinear energy sink(VTNES)with zero linear stiffness in the vertical direction is proposed and realized for the first *** motion differential equations of the VTNES coupled with a linear oscillator(LO)are *** the strong nonlinearity considered of the VTNES,the steady-state response of the system is analyzed with the harmonic balance method(HBM),and the accuracy of the HBM is verified *** this basis,the VTNES prototype is manufactured,and its nonlinear stiffness is *** damping effect and dynamic characteristics of the VTNES are studied theoretically and *** results show that the VTNES has better damping effects when strong modulation responses(SMRs)***,even for small-amplitude vibration,the VTNES also has a good vibration suppression *** sum up,in order to suppress the vertical vibration,an NES is designed and developed,which can suppress the vertical vibration within certain ranges of the resonance frequency and the vibration intensity.

关键词： track nonlinear energy sink(TNES) vertical direction gravity nonlinear stiffness harmonic balance method(HBM) vibration control

Deep structure of the Southeast Asian curved subduction system and its dynamic process

在线全文

学校读者我要写书评

暂无评论

Journal of Oceanology and Limnology 2024年第3期42卷 701-704页

作者： Weiwei ding Key Laboratory of Submarine Geoscience&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China

The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical *** on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was *** is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate *** work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.

关键词： curved subduction system deep structure material recycling dynamic process Southeast Asia

New advances in the study of Tethyan Geodynamic System

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2024年第3期67卷 874-878页

作者： Lin ding State Key Laboratory of Tibetan Plateau Earth System Science(LATPES) Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

Tethyan Ocean was initially proposed by Austrian geologist Eduard Suess in 1893. The study of the Tethyan evolution by European geologists has led to the development of modern geology, but not to the establishment of plate tectonics theory(Trümpy, 2001). With the progress in various studies, the concept of Tethys has evolved from a Mesozoic ocean into three long-term evolving oceans:Proto-Tethys, Paleo-Tethys, and Neo-Tethys (Figure 1), and their life cycles cover the entire Phanerozoic era (Wu et al., 2020).

关键词： geology Mesozoic ocean

同方期刊数据库