Artykuły w czasopismach: „Imact dynamics”

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Milić Beran, Ivona. "SYSTEM-DYNAMIC MODELING OF THE IMPACT OF SOCIAL CAPITAL ON ECONOMIC GROWTH". DIEM: Dubrovnik International Economic Meeting 6, nr 1 (wrzesień 2021): 25–32. http://dx.doi.org/10.17818/diem/2021/1.3.

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This paper presents a qualitative and quantitative system-dynamic modeling of the impact of social capital on economic growth. Social capital is the most problematic of all the concepts that determine progress. On a broad conceptual level, there is agreement about the importance of social capital, which has been used to explain differences in progress among nations with similar natural, human and physical capital. Recent research suggests that it is more important to include an explanation of the interaction of economic actors and their organization when measuring progress than to measure progress without the influence of social capital. The purpose of this paper is to develop a system-dynamic model of the impact of social capital on economic growth that will enable better understanding and management of social capital. In order to build a system dynamics model, the paper will: provide an analysis and overview of social capital and system dynamics; develop a system dynamics structural and mental-verbal model of the impact of social capital on economic growth; and develop a mathematical model of economic growth. This will provide a practical insight into the dynamic behavior of the observed system, i.e., analyzing economic growth and observing the mutual correlation between individual parameters. Keywords: social capital, economic growth, system dynamics, structural model

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Bae, Changwoo, Seungtae Oh, Jeonghoon Han, Youngsuk Nam i Choongyeop Lee. "Water penetration dynamics through a Janus mesh during drop impact". Soft Matter 16, nr 26 (2020): 6072–81. http://dx.doi.org/10.1039/d0sm00567c.

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Drop impact on a Janus membrane shows two distinct penetration dynamics: dynamic pressure driven penetration dynamics on a shorter timescale and capillary pressure driven penetration dynamics on a longer timescale.

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Mao, Jian, Yu Fu i Peichao Li. "Dynamics of Periodic Impulsive Collision in Escapement Mechanism". Shock and Vibration 20, nr 5 (2013): 1001–10. http://dx.doi.org/10.1155/2013/350429.

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Among various non-smooth dynamic systems, the periodically forced oscillation system with impact is perhaps the most common in engineering applications. The dynamical study becomes complicated due to the impact. This paper presents a systematic study on the periodically forced oscillation system with impact. A simplified model of the escapement mechanism is introduced. Impulsive differential equation and Poincare map are applied to describe the model and study the stability of the system. Numerical examples are given and the results show that the model is highly accurate in describing/predicting their dynamics.

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Caux, S., i R. Zapata. "Modeling and control of biped robot dynamics". Robotica 17, nr 4 (lipiec 1999): 413–26. http://dx.doi.org/10.1017/s0263574799001411.

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This paper addresses the problem of modeling biped dynamics and the use of such models for the control of walking, running and jumping robots. We describe two approaches to dynamic modeling: the basic Lagrange approach and the non-regular dynamic approach. The new non-regular dynamic approach takes into account discontinuities due to rigid contact between punctual feet and the ground without computing the exact impact time. The contact is close to the physical situation given by non-linear laws (impenetrability, non-smooth contact and real friction cone). Contact dynamics can be well managed with an accurate dynamic model that respects energy consistency during all the phases encountered during a step (0, 1 or 2 contacts). With this model, we can first study the equilibrum of a biped standing on one foot by a linearisation method. In the second stage, the unified modelized equation is used to establish a general control frame based on non-regular dynamical decoupling. A comparison is made and some simulation results are given with a two degree of freedom planar biped robot.

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Sun, Ao, i Ting Qiang Yao. "Modeling and Analysis of Planar Multibody System Containing Deep Groove Ball Bearing with Slider-Crank Mechanism". Advanced Materials Research 753-755 (sierpień 2013): 918–23. http://dx.doi.org/10.4028/www.scientific.net/amr.753-755.918.

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With the rotating machinery system developing toward high speed, high precision, and high reliability direction, ball bearing dynamic performance have a critical impact to dynamics characteristics of support system. Based on multibody dynamics theory and contact dynamics method,and considering the ball and ring raceway 3 d dynamic contact relationship, using ADAMS dynamics analysis software to establish the multibody dynamics model of crank slider mechanism containing ball bearing dynamic contact relationship.The simulation analysis of the dynamic performance of the ball bearing and the crank slider mechanism dynamics response, and the influence of dynamic performance for considering ball bearing rotating mechanical system dynamics analysis provides a reference method.The simulation analysts the influence of dynamic performance of the ball bearing to the crank slider mechanism dynamics response. It provides a reference method for rotating mechanical system dynamics analysis considering the dynamic performance of the ball bearing.

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Nie, Guang Hua, Shuai Zhang i Xue Fang Du. "Dynamics Simulation Analysis of Impact Mechanism in Impact Vibration Roller". Advanced Materials Research 765-767 (wrzesień 2013): 336–40. http://dx.doi.org/10.4028/www.scientific.net/amr.765-767.336.

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the paper adopts dynamic simulation software ADAMS for establishing virtual prototype model, and dynamics simulation analysis study is conducted on the impact mechanism in order to better study the impact mechanism in impact vibration composite roller with round idler wheels. The kinematics features and dynamics features are studied. The theoretical curves of rail disk opening size and driving angular velocity is obtained. The rail disk structure is improved, and it is proved through software simulation that the improved mechanism is beneficial for improving the impact efficiency of the roller.

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Zhang, Yu Bai, Hui Qun Yuan i Ming Xuan Liang. "Simulation Research on Tooth Root Dynamic Stress of Marine Helical Gear Meshing Impact". Applied Mechanics and Materials 331 (lipiec 2013): 7–10. http://dx.doi.org/10.4028/www.scientific.net/amm.331.7.

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Finite element model of helical gear meshing of large burden marine is built based on explicit dynamics finite element method, dynamics stress variation of helical gear tooth is simulated under multiple working conditions, research is focused on the impact of changes in working conditions on the dynamic stress of the tooth root. The results show that helical gear pair speed and center distance error have great impact on dynamic stress of tooth root. The results provide reference for dynamic performance optimization of marine gears.

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Duan, Yue Chen, Xia Li, Wei Wei Zhang, Guo Ning Liu i Ting Ting Wang. "Impact Dynamics of Flexible Multibody System Based on Continuous Contact Force Method". Applied Mechanics and Materials 744-746 (marzec 2015): 1628–34. http://dx.doi.org/10.4028/www.scientific.net/amm.744-746.1628.

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The impact dynamics of spatial multi-link flexible multibody system is studied based on the continuous contact force method (CCFM). According to the rigid-flexible coupling dynamic theory of flexible multibody system, the rigid-flexible coupling continuous dynamic equations of the system are established by using the recursive Lagrange method. The impact dynamic equations of the system are stylized derived on the use of CCFM basing on the nonlinear spring-damper model. The contact separation criterion is given to achieve the conversion and calculation of the dynamic model for the system at different stages. An impact dynamic simulation example for a two-link planar flexible multibody system is given, as well as the global dynamic response. The results show that the impact dynamic solving method based on CCFM can be used for the global impact dynamics of multi-link flexible multibody systems. The dynamic behavior of the system changes dramatically during the impact process. The large overall motion, the small deformation motion and the impact effect are coupled.

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Kamal, Tvezhar, i Shram Shawkat. "Impact of Dynamic Capabilities on Knowledge Management in Kurdistan Region of Iraq". Black Sea Journal of Management and Marketing 1, nr 1 (25.08.2020): 41–48. http://dx.doi.org/10.47299/bsjmm.v1i1.30.

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There are different factors that contribute and affect Knowledge Management such as the management system, teamwork, and dynamic capabilities within the organization. The aim of this study is to investigate dynamic capabilities of a firm and their impact on knowledge management at various companies in the Kurdistan Region of Iraq. Furthermore, it is aimed to examine the effects of employee experience on dynamic capabilities and knowledge management. Driven from the results, it was observed that organizational dynamics is one of the significant indicators of knowledge management. Secondly, the findings have revealed that experience is an important moderator between organizational dynamics and knowledge management.

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Qin, Zhenhua, i Rongjun Gai. "Neuro-Based Consensus Seeking for Nonlinear Uncertainty Multi-Agent Systems Constrained by Dead-Zone Input". International Journal on Semantic Web and Information Systems 19, nr 1 (25.08.2023): 1–26. http://dx.doi.org/10.4018/ijswis.328767.

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The topic about consensus target track seeking for high-order nonlinear multi-agent systems (MASs) with unmodeled dynamics, dynamic disturbances, and dead-zone input is considered in the paper. Using the strong nonlinear map characteristic of radial basis function neural networks (RBFNNs), the complex functions arising from recursive procedure are simplified. Also, inspired by input-to-state practical stability (ISpS), the authors construct a dynamical signal in order to counteract the impact of unmodeled dynamics and dynamic disturbances. The bounded inequality expression has been applied to tackle the unknown input of dead zone. Based on this, consensus control protocol suitable for nonlinear constraints has been constructed by using the recursive backstepping technique and adaptive neural network method. Theoretical analysis indicates not only the uniform boundary of all signals in the closed-loop under the neuro-based consensus controller, but uniform ultimate convergence of consensus tracking errors. The final simulations also confirmed the correctness of the theoretical analysis.

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Sheng, Yun, i Guangqiang Wu. "58857 Study on the Characteristics of Vehicle Full Frontal Impact Based on the Integrated Primary and Secondary Impact Model (IPSIM)(Vehicle Dynamics & Control including Tire Dynamics)". Proceedings of the Asian Conference on Multibody Dynamics 2010.5 (2010): _58857–1_—_58857–9_. http://dx.doi.org/10.1299/jsmeacmd.2010.5._58857-1_.

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Kurth, Jutta G., Thorsten Rings i Klaus Lehnertz. "Testing Jump-Diffusion in Epileptic Brain Dynamics: Impact of Daily Rhythms". Entropy 23, nr 3 (5.03.2021): 309. http://dx.doi.org/10.3390/e23030309.

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Stochastic approaches to complex dynamical systems have recently provided broader insights into spatial-temporal aspects of epileptic brain dynamics. Stochastic qualifiers based on higher-order Kramers-Moyal coefficients derived directly from time series data indicate improved differentiability between physiological and pathophysiological brain dynamics. It remains unclear, however, to what extent stochastic qualifiers of brain dynamics are affected by other endogenous and/or exogenous influencing factors. Addressing this issue, we investigate multi-day, multi-channel electroencephalographic recordings from a subject with epilepsy. We apply a recently proposed criterion to differentiate between Langevin-type and jump-diffusion processes and observe the type of process most qualified to describe brain dynamics to change with time. Stochastic qualifiers of brain dynamics are strongly affected by endogenous and exogenous rhythms acting on various time scales—ranging from hours to days. Such influences would need to be taken into account when constructing evolution equations for the epileptic brain or other complex dynamical systems subject to external forcings.

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Fang, Wei, Kaixuan Zhang, Qi Jiang, Cunjing Lv, Chao Sun, Qunyang Li, Yanlin Song i Xi-Qiao Feng. "Drop impact dynamics on solid surfaces". Applied Physics Letters 121, nr 21 (21.11.2022): 210501. http://dx.doi.org/10.1063/5.0124256.

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Drop impact on solid surfaces widely occurs both in nature and engineering. In this Perspective, we review the recent advances in experimental, theoretical, and numerical investigations of drop impact dynamics on solid surfaces. The relevant theoretical models and numerical methods, such as the wetting transition models and the volume-of-fluid method, are briefly described. The influences of key factors on the drop impact dynamics, and the underlying mechanisms of forces and energies, are examined. Especially, we analyze the contact time for a drop impacting on a solid surface and discuss the effective strategies to tune the dynamic impact behavior. The design principles of functional surfaces and some typical applications are also discussed. Finally, Perspectives are given on future development of the drop impact dynamics and its potential applications in diverse engineering fields.

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Mousseau, R., i G. Markale. "Obstacle Impact Simulation of an ATV Using an Efficient Tire Model". Tire Science and Technology 31, nr 4 (1.10.2003): 248–69. http://dx.doi.org/10.2346/1.2135271.

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Abstract When a vehicle travels over a large obstacle at a significant speed, dynamic loads are created that are severe enough to cause damage to its components. Prediction of these impact loads early in the design can greatly aid the vehicle development process. Thus, automobile manufactures have devoted considerable effort developing computer models to simulate durability events. An important part of any durability simulation is the tire model. This paper focuses on the problem of efficiently predicting dynamic loads that occur when an all terrain vehicle (ATV) impacts obstacle impact. An ATV simulation model that uses an efficient and simple tire model to represent the enveloping behavior and dynamic response was developed with the AUTOSIM multibody dynamics program. This program, using Kane's Method and symbolic algebra to automatically generate fully parametric simulations that are both efficient and easy to use, was used to model both the tire and ATV rigid body dynamics. This paper describes the combined ATV multi-body vehicle dynamics and tire simulation. To demonstrate the effectiveness of tire simulation, results from the efficient tire model isolated from the vehicle are compared to output from a nonlinear finite element model. Also, the paper compares results from the full vehicle ATV simulation and a field test.

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Mo, Shuai, Ting Zhang, Guoguang Jin, Zhanyong Feng, Jiabei Gong i Shengping Zhu. "Dynamic Characteristics and Load Sharing of Herringbone Wind Power Gearbox". Mathematical Problems in Engineering 2018 (31.10.2018): 1–24. http://dx.doi.org/10.1155/2018/7251645.

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In this study, the dynamic model for the herringbone planetary gear transmission system is established by the lumped parameter method based on the system dynamics and the Lagrange equation, and the impact of the support stiffness and the torsional stiffness on dynamic characteristics is studied. The research results have a guiding significance for the design of the herringbone gear transmission system. In this model, the herringbone gear is treated as a special gear coupled by 2 opposite helical gears, where the stagger angle, comprehensive meshing error, support stiffness, support damping, and load inertia are considered in the analysis of dynamics. Moreover, the dynamic characteristic of the carrier is considered as well. By calculating the meshing force curve of the transmission system, the impact of the stagger angle, supporting stiffness, and the torsional stiffness on meshing force and load sharing coefficient is analyzed. The results show that the stagger angle has an obvious impact on load sharing coefficient while it has little impact on maximum meshing force. And the support stiffness has a more obvious impact on the dynamic characteristics of the system. The recommendary support stiffness of the system is that all of the support stiffness of the sun gear, planetary gear, ring gear, and carrier is 107 N/m. The torsional stiffness has little impact on the dynamic characteristics of transmission system, except the torsional stiffness of planetary gear, and carrier has an obvious impact on load sharing coefficient. The commercial software ADAMS carried out dynamics analysis of the transmission system to verify the necessity validity of the theoretical analysis.

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Müller, Norbert. "River dynamics and floodplain vegetation and their alterations due to human impact". River Systems 9, nr 3-4 (12.02.1996): 477–512. http://dx.doi.org/10.1127/lr/9/1996/477.

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Leary, Matthew, Curtis Rusch, Zhe Zhang i Bryson Robertson. "Comparison and Validation of Hydrodynamic Theories for Wave Energy Converter Modelling". Energies 14, nr 13 (1.07.2021): 3959. http://dx.doi.org/10.3390/en14133959.

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Dynamic Wave Energy Converter (WEC) models utilize a wide variety of fundamental hydrodynamic theories. When incorporating novel hydrodynamic theories into numerical models, there are distinct impacts on WEC rigid body motions, cable dynamics, and final power production. This paper focuses on developing an understanding of the influence several refined hydrodynamic theories have on WEC dynamics, including weakly nonlinear Froude-Krylov and hydrostatic forces, body-to-body interactions, and dynamic cable modelling. All theories have evolved from simpler approaches and are of importance to a wide array of WEC archetypes. This study quantifies the impact these theories have on modelling accuracy through a WEC case study. Theoretical differences are first explored in a regular sea state. Subsequently, numerical validation efforts are performed against field data following wave reconstruction techniques. Comparisons of significance are WEC motion and cable tension. It is shown that weakly nonlinear Froude-Krylov and hydrostatic force calculations and dynamic cable modelling both significantly improve simulated WEC dynamics. However, body-to-body interactions are not found to impact simulated WEC dynamics.

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Wei, Yufen, Guoyou Han, Lingyi Yang i Haiying Zu. "Research on Dynamic Characteristics of Rub-Impact of Progressive Cavity Pump with Rotation Speed". Advances in Engineering Technology Research 1, nr 2 (23.09.2022): 148. http://dx.doi.org/10.56028/aetr.1.2.148.

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The dynamic characteristics of Progressive Cavity Pump (PCP) have an important influence on the stability of oil wells string system. A nonlinear dynamics model of rotor system was presented. The equations of unbalance rotor were established by the Lagrange approach and the vibration characteristics of the rotor system under rub-impact was analyzed by used the modern nonlinear dynamics and bifurcation theories, through numerical calculation. The bifurcation diagrams, time domain charts and Poincaré maps were obtained to analyze dynamic characteristics of the system and the results reveal the multiform complex nonlinear dynamic behavior of the rotor-bearing system under rub-impact. Moreover, the influence of the speed on the relatively stable speed of the rotor system was analyzed. These analysis results provide theoretical bases for the rotor system's status recognition, diagnosis as well as safe and economic operation.

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Wei, Yufen, Guoyou Han, Lingyi Yang i Haiying Zu. "Research on Dynamic Characteristics of Rub-Impact of Progressive Cavity Pump with Rotation Speed". Advances in Engineering Technology Research 2, nr 1 (23.09.2022): 148. http://dx.doi.org/10.56028/aetr.2.1.148.

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The dynamic characteristics of Progressive Cavity Pump (PCP) have an important influence on the stability of oil wells string system. A nonlinear dynamics model of rotor system was presented. The equations of unbalance rotor were established by the Lagrange approach and the vibration characteristics of the rotor system under rub-impact was analyzed by used the modern nonlinear dynamics and bifurcation theories, through numerical calculation. The bifurcation diagrams, time domain charts and Poincaré maps were obtained to analyze dynamic characteristics of the system and the results reveal the multiform complex nonlinear dynamic behavior of the rotor-bearing system under rub-impact. Moreover, the influence of the speed on the relatively stable speed of the rotor system was analyzed. These analysis results provide theoretical bases for the rotor system's status recognition, diagnosis as well as safe and economic operation.

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Habtour, Ed, William (Skip) Connon, Michael F. Pohland, Samuel C. Stanton, Mark Paulus i Abhijit Dasgupta. "Review of Response and Damage of Linear and Nonlinear Systems under Multiaxial Vibration". Shock and Vibration 2014 (2014): 1–21. http://dx.doi.org/10.1155/2014/294271.

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A review of past and recent developments in multiaxial excitation of linear and nonlinear structures is presented. The objective is to review some of the basic approaches used in the analytical and experimental methods for kinematic and dynamic analysis of flexible mechanical systems, and to identify future directions in this research area. In addition, comparison between uniaxial and multiaxial excitations and their impact on a structure’s life-cycles is provided. The importance of understanding failure mechanisms in complex structures has led to the development of a vast range of theoretical, numerical, and experimental techniques to address complex dynamical effects. Therefore, it is imperative to identify the failure mechanisms of structures through experimental and virtual failure assessment based on correctly identified dynamic loads. For that reason, techniques for mapping the dynamic loads to fatigue were provided. Future research areas in structural dynamics due to multiaxial excitation are identified as (i) effect of dynamic couplings, (ii) modal interaction, (iii) modal identification and experimental methods for flexible structures, and (iv) computational models for large deformation in response to multiaxial excitation.

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Michaľčonok, German, Maximilián Strémy i Andrej Eliáš. "Quality and Dynamic Characteristics of Control System Visualization in Control Web". Research Papers Faculty of Materials Science and Technology Slovak University of Technology 19, nr 30 (1.01.2011): 67–72. http://dx.doi.org/10.2478/v10186-010-0041-z.

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Quality and Dynamic Characteristics of Control System Visualization in Control Web Progress of information technologies and their applications create the necessary need to explore the analysis of techniques to estimate the impact of architecture control system on dynamic characteristics of control. Major impact factors on dynamics and quality of visualization, control modes selection and impact analysis are described in the article.

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Zhu, Zhiqiang. "Control Analysis of Propagation Dynamics on Networks". Journal of Physics: Conference Series 2224, nr 1 (1.04.2022): 012092. http://dx.doi.org/10.1088/1742-6596/2224/1/012092.

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Abstract It is generally the dynamic behavior of multiple information in the network. Based on the principle of propagation dynamics and mathematical model, this paper simulates the dynamic process of information in the network, and analyzes the influence of network structure and propagation dynamics on the dynamic behavior of information in the network through the simulation results. By simulating the dynamic process of communication, we find that the location and release time of intervention information in the network will have an impact, and we can control the dynamic behavior of information in the network by controlling the location and release time of intervention information.

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Duan, Yue Chen, i Ding Guo Zhang. "Rigid-Flexible Coupling Dynamics of a Flexible Robot with Impact". Advanced Materials Research 199-200 (luty 2011): 243–50. http://dx.doi.org/10.4028/www.scientific.net/amr.199-200.243.

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The rigid-flexible coupling dynamics of a radially rotating flexible beam with impact is investigated in this paper. The transversal deformation and nonlinear coupled deformation, which means the longitudinal shortening caused by transversal deformation, is considered here. The impact force is calculated based on Hertz contact theory and nonlinear damping theory. By introducing the concept of impact potential energy, the system’s rigid-flexible coupling dynamic equations with impact is obtained by using Lagrange equation. The dynamic simulation is given to validate the method presented here, and get some dynamic response, such as impact force and flexible deformation.

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Liu, Yang, Yinghou Jiao, Shiyuan Qi, Guangbin Yu i Mengdi Du. "Study on the Nonlinear Dynamic Behavior of Rattling Vibration in Gear Systems". Machines 10, nr 12 (23.11.2022): 1112. http://dx.doi.org/10.3390/machines10121112.

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To reveal the nonlinear dynamic behavior of gear rattling vibration caused by gear backlash, a 2-DOF oscillator model with spring and damping elements was established. Based on the theory of discontinuous dynamical systems, the phase plane of gear motion was divided into three parts: the domain of tooth surface meshing motion, the domain of free motion and the domain of tooth back meshing motion. Introducing the global mapping and local mapping dynamics method, the process of gear teeth from impact to meshing and then impact and meshing was accurately described. The influence of different restitution coefficients on gear impact-meshing motion was studied by numerical simulation. The results showed that the grazing bifurcation caused by gear backlash will lead to complex mapping structures of the system and even chaos. The restitution coefficient directly affects the impact-meshing behavior. The introduction of meshing stiffness and restitution coefficient can reasonably characterize the elastic deformation and energy loss during gear meshing, which provides a theoretical model for the application of the theory of discontinuous dynamical systems to a more complex multi-degree of freedom flexible contact gear transmission system.

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Ivanova, Kseniya, i Aleksey Kolos. "Dynamic Forces of Wheel Impact on Rail at Ballastless Track Structure RHEDA 2000". Bulletin of scientific research results 2023, nr 1 (27.03.2023): 197–205. http://dx.doi.org/10.20295/2223-9987-2023-1-197-205.

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Purpose: Experimental determination of vertical dynamic forces of wheel impact on a rail at ballastless construction of railway track RHEDA2000 upper structure with subsequent analysis of obtained data; definition of main factors affecting vertical dynamic force value; identification of dependence of change in the value of wheel vertical dynamic force impact on a rail from motion speed and rolling stock type; calculation of coefficients of vertical dynamics at ballastless construction of rail upper structure. Methods: Measurement of wheel vertical dynamic force impact on a rail was carried out by strain-gauge method (Schlumpf method). Numerical values of those, obtained in the course of experiment, were processed by mathematical statistics method, in its turn, probability level was taken equal to 0.994. Results: The values of vertical dynamic forces of wheel impact on a rail for ballastless structure of RHEDA2000 type at rolling stock different types and various ranges of motion speed have been determined. The dependence of change in the value of wheel vertical dynamic force impact on a rail from motion speed and rolling stock type has been graphically built. Comparison of vertical dynamics coefficients of ballastless construction of railway RHEDA2000 upper structure with the construction of a track on a ballast has been carried out. Practical significance: The obtained results can be used in projection, construction, reconstruction and repair of railway track where track ballastless upper composition is provided.

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Chikore, Tichaona, Farai Nyabadza i K. A. Jane White. "Exploring the Impact of Nonlinearities in Police Recruitment and Criminal Capture Rates: A Population Dynamics Approach". Mathematics 11, nr 7 (30.03.2023): 1669. http://dx.doi.org/10.3390/math11071669.

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The interplay between criminal activity and crime control/prevention measures is inherently dynamic. This paper presents a simple nonlinear dynamical system in which criminal activity levels are coupled to policing effort. Through the process of non-dimensionalisation and sensitivity analysis, policing efficiency and the responsiveness of policing effort are identified as key parameter groupings. An analysis of the system shows that bi-stability is a feature of the dynamics. When there is no feedback between criminal activity and police recruitment, a saddle-node bifurcation occurs and threshold levels of criminal activity are required for the activity to be maintained. When feedback is permitted, we also find a backward bifurcation and criminal activity can be contained for policing efficiency below its threshold level. We demonstrate proof of concept for how the model might be used as a predictive tool with real data.

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Zhao, Da Peng, Xiong Fei Wei i Sheng Xiang Chen. "An Experimental Study of Head Stack Assembly Dynamics Impact on Head Disc Interaction". Applied Mechanics and Materials 311 (luty 2013): 222–25. http://dx.doi.org/10.4028/www.scientific.net/amm.311.222.

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As head-disk clearance has been reduced to nearly 1 nm, air bearing slider dynamic stability becomes increasingly important. This paper presents an experimental study about the coupling effects of Head Gimbal Assembly (HGA) dynamics and arm vibration on Head Disk Interaction (HDI). HDI dynamics was evaluated on a disc with defect. It was found that a much bigger vibration of the slider was observed when suspension local bending mode and arm bending mode are closed to each other than the situation that the two modes are separated. It is proved that both HGA and arm are related to HDI dynamics in a hard disc drive. This study is helpful to characterize system dynamics for robust HDI design.

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Lan, Tian, Kairong Lin, Chong-Yu Xu, Zhiyong Liu i Huayang Cai. "A framework for seasonal variations of hydrological model parameters: impact on model results and response to dynamic catchment characteristics". Hydrology and Earth System Sciences 24, nr 12 (8.12.2020): 5859–74. http://dx.doi.org/10.5194/hess-24-5859-2020.

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Abstract. Previous studies have shown that the seasonal dynamics of model parameters can compensate for structural defects of hydrological models and improve the accuracy and robustness of the streamflow forecast to some extent. However, some fundamental issues for improving model performance with seasonal dynamic parameters still need to be addressed. In this regard, this study is dedicated to (1) proposing a novel framework for seasonal variations of hydrological model parameters to improve model performance and (2) expanding the discussion on model results and the response of seasonal dynamic parameters to dynamic characteristics of catchments. The procedure of the framework is developed with (1) extraction of the dynamic catchment characteristics using current data-mining techniques, (2) subperiod calibration operations for seasonal dynamic parameters, considering the effects of the significant correlation between the parameters, the number of multiplying parameters, and the temporal memory in the model states in two adjacent subperiods on calibration operations, and (3) multi-metric assessment of model performance designed for various flow phases. The main finding is that (1) the proposed framework significantly improved the accuracy and robustness of the model; (2) however, there was a generally poor response of the seasonal dynamic parameter set to catchment dynamics. Namely, the dynamic changes in parameters did not follow the dynamics of catchment characteristics. Hence, we deepen the discussion on the poor response in terms of (1) the evolutionary processes of seasonal dynamic parameters optimized by global optimization, considering that the possible failure in finding the global optimum might lead to unreasonable seasonal dynamic parameter values. Moreover, a practical tool for visualizing the evolutionary processes of seasonal dynamic parameters was designed using geometry visualization techniques. (2) We also discuss the strong correlation between parameters considering that dynamic changes in one parameter might be interfered with by other parameters due to their interdependence. Consequently, the poor response of the seasonal dynamic parameter set to dynamic catchment characteristics may be attributed in part to the possible failure in finding the global optimum and strong correlation between parameters. Further analysis also revealed that even though individual parameters cannot respond well to dynamic catchment characteristics, a dynamic parameter set could carry the information extracted from dynamic catchment characteristics and improve the model performance.

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Lu, Ning, i Jian Mao. "Dynamics Analysis for Periodically Forced Oscillation System". Advanced Materials Research 139-141 (październik 2010): 2427–30. http://dx.doi.org/10.4028/www.scientific.net/amr.139-141.2427.

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Among various non-smooth dynamic systems, the periodically forced oscillation system with impact is the most common in engineering applications. The dynamics becomes complicate due to the impact against the stops. This paper presented a systematic study on the periodically forced oscillation system with impact. In particular, impulsive differential equation, Poincare map is applied. The proposed model has high numerical accuracy in describing their dynamics. It helps to optimize the design of a commercial product.

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Harton, Helen C., Laura R. Green, Craig Jackson i Bibb Latané. "Demonstrating Dynamic Social Impact: Consolidation, Clustering, Correlation, and (Sometimes) the Correct Answer". Teaching of Psychology 25, nr 1 (styczeń 1998): 31–35. http://dx.doi.org/10.1207/s15328023top2501_9.

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This demonstration illustrates principles of group dynamics and dynamic social impact and can be used in classes in social psychology or group dynamics. Students discuss their answers to multiple-choice questions with neighbors and answer them again. Discussion consistently leads to the consolidation (reduced diversity), clustering (spatial-self-organization), correlation (emergent linkages), and continuing diversity of responses. “Truth” does not necessarily win, showing that the social reality of the group may be more important than objective reality.

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Xia, Wen Min, i Xue Mei Liu. "The Response Analysis of the Train-Bridge System under Seismic Action". Applied Mechanics and Materials 587-589 (lipiec 2014): 1443–47. http://dx.doi.org/10.4028/www.scientific.net/amm.587-589.1443.

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This article based on bridge structural dynamics, vehicle dynamics and soil dynamics theory, set up the practical space mode, with an example of a dual-line 32 m single box section beam on Beijing-Shanghai Railway Line. According to the typical soft soil sites of Shanghai, the dynamic response of the bridge was analyzed by the large finite element software ANSYS under seismic action. Moreover the impact about the dynamic interaction of pile-soil-structure affecting on the design of high-speed railway bridges was got which will provide reference and basis for the construction and design similar project.

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Qian, Zhen Jie, i Ding Guo Zhang. "Impact Dynamics of Multi-Link Robots with Link and Joint Flexibility". Applied Mechanics and Materials 226-228 (listopad 2012): 685–92. http://dx.doi.org/10.4028/www.scientific.net/amm.226-228.685.

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The dynamic analysis of a flexible-link-joint robot colliding with its environments is presented in this paper. Kinematics of both rotary-joint motion and link deformation is described by 4×4 homogenous transformation matrices. Both the stretching deformation, bending deformation and the torsional deformation of the flexible links are considered. Furthermore, the flexibility and the mass of the joint are considered too. The concept of impact force potential energy is introduced, so that the generalized forces due to the impact force can be computed easily. The Lagrange dynamic equations are used to establish the complete mathematic model of the system with impact. Dynamics simulation of a spatial flexible-link-joint manipulator arm is given as an example to validate the algorithm presented in this paper. And the numerical results indicate that the flexibility of the link and joint have distinguished influence on the impact dynamics of the flexible robots.

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Wang, Guo Hui, i Bo Zhao. "Dynamic Analysis of Electrical Control Components under Tank Gun Firing Impact". Applied Mechanics and Materials 628 (wrzesień 2014): 235–39. http://dx.doi.org/10.4028/www.scientific.net/amm.628.235.

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To acquire the dynamic characteristics of electrical control component under tank gun firing impact, the author simplified tank structure, combined the three-dimensional modeling software Solidworks and dynamics simulation software ADAMS, constructed a full vehicle dynamics simulation model of a main battle tank and simulated the firing of tank gun. The compare between experimental and simulated results proved the validity and reliability of this model. This set the foundation for the analysis of fault principles of fire control computer and its internal structure under the impact of tank gun firing.

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Mattia, Maurizio, i Paolo Del Giudice. "Efficient Event-Driven Simulation of Large Networks of Spiking Neurons and Dynamical Synapses". Neural Computation 12, nr 10 (1.10.2000): 2305–29. http://dx.doi.org/10.1162/089976600300014953.

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A simulation procedure is described for making feasible large-scale simulations of recurrent neural networks of spiking neurons and plastic synapses. The procedure is applicable if the dynamic variables of both neurons and synapses evolve deterministically between any two successive spikes. Spikes introduce jumps in these variables, and since spike trains are typically noisy, spikes introduce stochasticity into both dynamics. Since all events in the simulation are guided by the arrival of spikes, at neurons or synapses, we name this procedure event-driven. The procedure is described in detail, and its logic and performance are compared with conventional (synchronous) simulations. The main impact of the new approach is a drastic reduction of the computational load incurred upon introduction of dynamic synaptic efficacies, which vary organically as a function of the activities of the pre- and postsynaptic neurons. In fact, the computational load per neuron in the presence of the synaptic dynamics grows linearly with the number of neurons and is only about 6% more than the load with fixed synapses. Even the latter is handled quite efficiently by the algorithm. We illustrate the operation of the algorithm in a specific case with integrate-and-fire neurons and specific spike-driven synaptic dynamics. Both dynamical elements have been found to be naturally implementable in VLSI. This network is simulated to show the effects on the synaptic structure of the presentation of stimuli, as well as the stability of the generated matrix to the neural activity it induces.

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Gao, Qin He, i Xiang Yang Li. "Research on Dynamic Modelling and Simulation of Erection System of Mobile Equipment in Absolute Coordinates". Applied Mechanics and Materials 66-68 (lipiec 2011): 2034–40. http://dx.doi.org/10.4028/www.scientific.net/amm.66-68.2034.

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This paper employed the theories of multibody system dynamics to analyze the multi-rigid-body model of erection system and build the general dynamic models in absolute coordinates. The impact theory of contact mechanics and nonlinear spring-damper force function were used to model the impact problems between rods of multi-stage hydraulic cylinder of erection system and educe the dynamic models of multi-rigid-body erection system with impact. An automatic violation correction method according to the step of integration time was given to solve the violation which is an incident problem in numerical integration of dynamic models in absolute coordinates. Simulation results show that these dynamic models are effective.

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Smith, Samuel, Paul W. Staten i Jian Lu. "How Moist and Dry Intrusions Control the Local Hydrologic Cycle in Present and Future Climates". Journal of Climate 34, nr 11 (czerwiec 2021): 4343–59. http://dx.doi.org/10.1175/jcli-d-20-0780.1.

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AbstractModels disagree on how much the hydrologic cycle could intensify under climate change. These changes are expected to scale with the Clausius–Clapeyron relation but may locally diverge due in part to the uncertain response of the general circulation, causing the hydrologic cycle to inherit this uncertainty. To identify how the circulation contributes, we link circulation changes to changes in the higher moments of the hydrologic cycle using the novel dynamical framework of the local hydrologic cycle, the portion of the hydrologic cycle driven by moist or dry intrusions. We expand this dynamical framework, developing a closed budget that diagnoses thermodynamic, advective, and overturning contributions to future hydrologic cycle changes. In analyzing these changes for the Community Earth System Model Large Ensemble, we show that overturning is the main dynamic contributor to the tropical and subtropical annual response, consistent with a weakening of this circulation. In the extratropics, we show that advective contributions, likely from storm track changes, dominate the response. We achieve a cleaner separation between dynamic and thermodynamic contributions through a semiempirical scaling, which reveals the robustness of the Clausius–Clapeyron scaling for the local hydrologic cycle. This scaling also demonstrates the slowing of the local hydrologic cycle and how changing subtropical dynamics asymmetrically impact wave breaking and suppress meridional moisture transport. We conclude that dynamic changes in the subtropics are predominantly responsible for the annual, dynamic response in the extratropics and thus a significant contributor to uncertainty in future projections.

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Linker, Stephanie M., Christian Schellhaas, Benjamin Ries, Hans-Jörg Roth, Marianne Fouché, Stephane Rodde i Sereina Riniker. "Polar/apolar interfaces modulate the conformational behavior of cyclic peptides with impact on their passive membrane permeability". RSC Advances 12, nr 10 (2022): 5782–96. http://dx.doi.org/10.1039/d1ra09025a.

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Rivera-Morán, J. Alejandro, Yi Liu, Samuel Monter, Chiao-Peng Hsu, Pia Ruckdeschel, Markus Retsch, Maciej Lisicki i Peter R. Lang. "The effect of morphology and particle–wall interaction on colloidal near-wall dynamics". Soft Matter 17, nr 45 (2021): 10301–11. http://dx.doi.org/10.1039/d1sm01191j.

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Sun, Xiuquan, Ruiliang Zhang, Zuolu Wang, Tie Wang, Fengshou Gu, Andrew D. Ball i Bo Liang. "Investigation of Spur Gear Dynamics with Gear MeshImpacts Induced by Tooth Wear". Journal of Physics: Conference Series 2184, nr 1 (1.03.2022): 012039. http://dx.doi.org/10.1088/1742-6596/2184/1/012039.

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Abstract Tooth wear is one of the most common faults in gear transmission systems. However, due to its limited influences on gear dynamics, the condition monitoring of gear wear experiences more challenges. To investigate the relationship between tooth wear and gear dynamics, this study develops an eight-degree of freedom dynamic model which takes into account the gear mesh impact induced by tooth wear. In this model, the gear mesh impact force induced by tooth wear was calculated as an extra input excitation for the gear dynamic model. Besides, a comparative study was carried out to explore the real reason that causes the poor dynamic behaviour due to the wear from two points of view: 1) the reduction in gear mesh stiffness; 2) the increase in gear mesh impact force. The simulation results show that the wear causes a slight reduction in gear mesh stiffness, thus leading to the decrease in the amplitude of gear mesh frequency. This is not consistent with the phenomena observed in the lab experiment which shows the increase in the gear vibrations. The second simulation of impact force demonstrates that the wear causes an increase in the impact force which further leads to the increase in the amplitude of gear mesh frequency. This study investigates the cause for the deterioration in gear dynamics induced by gear wear, which can benefit the early condition monitoring and fault diagnosis of the gear tooth wear.

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Angelova, Elena, i Hassan Chamati. "Dynamic simulation of the quasiparticle excitations spectra in the magnetic bcc iron". Journal of Physics: Conference Series 2436, nr 1 (1.01.2023): 012011. http://dx.doi.org/10.1088/1742-6596/2436/1/012011.

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Abstract We used the LAMMPS algorithm for spin-lattice dynamics to model the coupled relaxation processes of the spin and lattice subsystems in bcc Fe with the aim to investigate the relevant phonon and magnon dispersion laws at T = 300 K. The atomic interactions were modeled via the semi-empirical many-body Chamati EAM potential, while the distance-dependent spin coupling relied on the Heisenberg-type Hamiltonian. In the state of mutual equilibrium of the spin and lattice ensembles, we have calculated the dynamic matrix of the phonons, the intermediate scattering function, the dynamical structure factor and finally the phonon spectra in bcc-iron. We found that the experimental data could be described best by the elastic [100] and [110] modes calculated in the dynamic structure factor approach for all wavevector absolute values q. Moreover, the impact of magnons on the phonon spectra is pronounced for all investigated directions, but there are elastic vibrations which remain unaltered by interaction with magnons.

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Yaumil Utami, Fakhira, Ni Luh Arjani i Ni Made Wiasti Ni Made Wiasti. "Dinamika Pola Kepemimpinan Adat di Dusun Adat Karampuang Sulawesi Selatan". Sunari Penjor : Journal of Anthropology 4, nr 1 (11.07.2021): 24. http://dx.doi.org/10.24843/sp.2020.v4.i01.p04.

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This research discusses the dynamics of customary leadership patterns in the Karampuang customary hamlet of South Sulawesi and the impact of these dynamics. The problems that will be discussed in this research are (1) Why is there a dynamic of customary leadership patterns in Karampuang village (2) What is the impact of the dynamics of customary leadership patterns in Karampuang customary village. This research is a qualitative research using social change theory and leadership theory. as a basis for answering both problems. The results of this study reveal that the dynamics of customary leadership patterns in the Karampuang customary village are influenced by internal factors and external factors. The dynamics of customary leadership towards the community can be classified into several fields, namely the impact in the legal and environmental, economic, socio-cultural fields all of which have a beneficial impact on indigenous peoples; whereas the field of education is less profitable for indigenous peoples due to less motivation to demand higher education.

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Song, Yanyan, Boyan Chang, Guoguang Jin, Zhan Wei i Bo Li. "An Approach for the Impact Dynamic Modeling and Simulation of Planar Constrained Metamorphic Mechanism". Shock and Vibration 2020 (5.08.2020): 1–18. http://dx.doi.org/10.1155/2020/8837838.

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This paper studied the impact dynamic modeling of the planar constrained metamorphic mechanism (PCMM) during configuration transformation. Based on the dynamic theory of the multi-rigid-body system and the coefficient of restitution equation, a new method for dynamic modeling of PCMM considering impact motions generated by configuration transformation is presented, which can be treated as a theoretical foundation for performance design and dynamic control. Firstly, the topology theory based on the impact motion can be classified as the stable impact motion and the mobile impact motion, which is the prerequisite for dynamic modeling and simulation. Secondly, the stable and mobile impact dynamic models for PCMM are established according to the dynamic theory of the multi-rigid-body system. Then, using these models, the corresponding impulse solving models are deduced combining with the coefficient of restitution equation. Finally, the examples of the stable impact motion and the mobile impact motion are respectively given, and the configuration-complete dynamic simulations are carried out. By comparing with the dynamic models without considering the impact motion, the dynamic characteristics of PCMM are analyzed. The theory and method proposed in this paper can be also applied in general planar robotic systems to deal with the problem of internal collision dynamics.

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Ye, Ziyang, Changmin Yang i Honggang Li. "Dynamic Response of a Single-Pier Jacking of a Continuous Box Girder Bridge Based on Vehicle–Bridge Coupling". Applied Sciences 13, nr 16 (16.08.2023): 9287. http://dx.doi.org/10.3390/app13169287.

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In order to improve the bearing capacity of a bridge under dynamic impact and at the same time to improve the durability and safety of the bridge, the bridge should be jacked up, and most of the current research on bridge jacking upgrading is on synchronous jacking upgrading. There has been little research on single-pier jacking upgrading, especially the dynamics response problem under single-pier jacking upgrading of the bridge. This paper is based on the principle of vehicle–bridge coupling, and the vehicle was analyzed at different speeds by using the established model, vehicle weight, and multi-lane driving, comparing the dynamic response of the bridge before and after the single-pier jacking retrofit. The study analyzed the impact of the bridge single-pier jacking retrofit on the bridge impact coefficient, and evaluated the impact coefficient of the bridge from the perspective of dynamics. A comprehensive evaluation of the bridge single-pier jacking retrofit project was carried out. The following conclusions are drawn: the single-pier jacking modification of the bridge increased the bridge’s capacity under dynamic impact and also enhanced the durability and safety of the bridge.

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Zhang, Sara Q., T. Matsui, S. Cheung, M. Zupanski i C. Peters-Lidard. "Impact of Assimilated Precipitation-Sensitive Radiances on the NU-WRF Simulation of the West African Monsoon". Monthly Weather Review 145, nr 9 (1.09.2017): 3881–900. http://dx.doi.org/10.1175/mwr-d-16-0389.1.

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Abstract This work assimilates multisensor precipitation-sensitive microwave radiance observations into a storm-scale NASA Unified Weather Research and Forecasting (NU-WRF) Model simulation of the West African monsoon. The analysis consists of a full description of the atmospheric states and a realistic cloud and precipitation distribution that is consistent with the observed dynamic and physical features. The analysis shows an improved representation of monsoon precipitation and its interaction with dynamics over West Africa. Most significantly, assimilation of precipitation-affected microwave radiance has a positive impact on the distribution of precipitation intensity and also modulates the propagation of cloud precipitation systems associated with the African easterly jet. Using an ensemble-based assimilation technique that allows state-dependent forecast error covariance among dynamical and microphysical variables, this work shows that the assimilation of precipitation-sensitive microwave radiances over the West African monsoon rainband enables initialization of storms. These storms show the characteristics of continental tropical convection that enhance the connection between tropical waves and organized convection systems.

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Kawa, S. R., P. A. Newman, R. S. Stolarski i R. M. Bevilacqua. "Fall vortex ozone as a predictor of springtime total ozone at high northern latitudes". Atmospheric Chemistry and Physics Discussions 5, nr 1 (12.01.2005): 155–78. http://dx.doi.org/10.5194/acpd-5-155-2005.

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Abstract. Understanding the impact of atmospheric dynamical variability on observed changes in stratospheric O3 is a key to understanding how O3 will change with future climate dynamics and trace gas abundances. In this paper we examine the linkage between interannual variability in total column O3 at northern high latitudes in March and lower-to-mid stratospheric vortex O3 in the prior November. We find that these two quantities are significantly correlated in the years available from TOMS, SBUV, and POAM data (1978–2004). Additionally, we find that the apparent decadal shift in March O3 variability from the 1980s to years post-1990 is also seen in the November vortex O3, so that interannual variability in both quantities is largely driven by the later years. The cause of this correlation is not clear, however. Interannual variations in March total O3 are known to correspond closely with variations in winter stratospheric wave driving consistent with the effects of varying residual circulation, temperature, and chemical loss. Variation in November vortex O3 may also depend on dynamical wave activity, however, the dynamics in fall are less variable than in winter and spring. We do not find significant correlations of dynamic indicators for November such as temperature, heat flux, or polar average total O3 with the November vortex O3, nor with dynamical indicators later in winter and spring that might lead to a connection to March. We discuss several potential hypotheses for the observed correlation but do not find strong evidence for any considered mechanism. We present the observations as a phenomenon whose understanding may improve our ability to predict the dependence of O3 on changing dynamics and chemistry.

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Kawa, S. R., P. A. Newman, R. S. Stolarski i R. M. Bevilacqua. "Fall vortex ozone as a predictor of springtime total ozone at high northern latitudes". Atmospheric Chemistry and Physics 5, nr 6 (4.07.2005): 1655–63. http://dx.doi.org/10.5194/acp-5-1655-2005.

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Abstract. Understanding the impact of atmospheric dynamical variability on observed changes in stratospheric O3 is a key to understanding how O3 will change with future climate dynamics and trace gas abundances. In this paper we examine the linkage between interannual variability in total column O3 at northern high latitudes in March and lower-to-mid stratospheric vortex O3 in the prior November. We find that these two quantities are significantly correlated in the years available from TOMS, SBUV, and POAM data (1978-2004). Additionally, we find that the increase in March O3 variability from the 1980s to years post-1990 is also seen in the November vortex O3, i.e., interannual variability in both quantities is much larger in the later years. The cause of this correlation is not clear, however. Interannual variations in March total O3 are known to correspond closely with variations in winter stratospheric wave driving consistent with the effects of varying residual circulation, temperature, and chemical loss. Variation in November vortex O3 may also depend on dynamical wave activity, but the dynamics in fall are less variable than in winter and spring. We do not find significant correlations of dynamic indicators for November such as temperature, heat flux, or polar average total O3 with the November vortex O3, nor with dynamical indicators later in winter and spring that might lead to a connection to March. We discuss several potential hypotheses for the observed correlation but do not find strong evidence for any considered mechanism. We present the observations as a phenomenon whose understanding may improve our ability to predict the dependence of O3 on changing dynamics and chemistry.

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Leine, R. I., D. H. Van Campen i C. H. Glocker. "Nonlinear Dynamics and Modeling of Various Wooden Toys with Impact and Friction". Journal of Vibration and Control 9, nr 1-2 (styczeń 2003): 25–78. http://dx.doi.org/10.1177/107754603030741.

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In this paper, we study bifurcations in systems with impact and friction, modeled with a rigid multibody approach. Knowledge from the field of nonlinear dynamics is therefore combined with theory from the field of non-smooth mechanics. We study the nonlinear dynamics of three commercial wooden toys. The toys show complex dynamical behavior but can be studied with one-dimensional maps, which allows for a thorough analysis of the bifurcations.

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Toma, Milan, Shelly Singh-Gryzbon, Elisabeth Frankini, Zhenglun (Alan) Wei i Ajit P. Yoganathan. "Clinical Impact of Computational Heart Valve Models". Materials 15, nr 9 (5.05.2022): 3302. http://dx.doi.org/10.3390/ma15093302.

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This paper provides a review of engineering applications and computational methods used to analyze the dynamics of heart valve closures in healthy and diseased states. Computational methods are a cost-effective tool that can be used to evaluate the flow parameters of heart valves. Valve repair and replacement have long-term stability and biocompatibility issues, highlighting the need for a more robust method for resolving valvular disease. For example, while fluid–structure interaction analyses are still scarcely utilized to study aortic valves, computational fluid dynamics is used to assess the effect of different aortic valve morphologies on velocity profiles, flow patterns, helicity, wall shear stress, and oscillatory shear index in the thoracic aorta. It has been analyzed that computational flow dynamic analyses can be integrated with other methods to create a superior, more compatible method of understanding risk and compatibility.

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Dessens, Olivier, i Pascal Simon. "The importance of dynamics/chemistry coupling in the evaluation of aircraft emission impact studies". Meteorologische Zeitschrift 11, nr 3 (2.08.2002): 161–75. http://dx.doi.org/10.1127/0941-2948/2002/0011-0161.

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Xu, Shuqi, Manuel Sebastian Mariani i Linyuan Lü. "Modeling the dynamics of firms’ technological impact*". Chinese Physics B 30, nr 12 (1.12.2021): 120517. http://dx.doi.org/10.1088/1674-1056/ac364c.

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Recent studies in complexity science have uncovered temporal regularities in the dynamics of impact along scientific and other creative careers, but they did not extend the obtained insights to firms. In this paper, we show that firms’ technological impact patterns cannot be captured by the state-of-the-art dynamical models for the evolution of scientists’ research impact, such as the Q model. Therefore, we propose a time-varying returns model which integrates the empirically-observed relation between patent order and technological impact into the Q model. The proposed model can reproduce the timing pattern of firms’ highest-impact patents accurately. Our results shed light on modeling the differences behind the impact dynamics of researchers and firms.

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