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1
Zhang, W., X. Ding et J. Liu. « A representation of the configurations and evolution of metamorphic mechanisms ». Mechanical Sciences 7, no 1 (9 février 2016) : 39–47. http://dx.doi.org/10.5194/ms-7-39-2016.
Texte intégralRésumé :
Abstract. Metamorphic mechanisms are members of the class of mechanisms that are able to change their configurations sequentially to meet different requirements. The paper introduces a comprehensive symbolic matrix representation for characterizing the topology of one of these mechanisms in a single configuration using general information concerning links and joints. Furthermore, a matrix representation of an original metamorphic mechanism that has the ability to evolve is proposed by uniting the matrices representing all of the mechanism's possible configurations. The representation of metamorphic kinematic joints is developed in accordance with the variation laws of these mechanisms. By introducing the joint variation matrices derived from generalized operations on the related symbolic adjacency matrices, evolutionary relationships between mechanisms in adjacent configurations and the original metmaorphic mechanism are made distinctly. Examples are provided to demonstrate the validation of the method.
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Zhai, Guangqing, Jianguo Tao, Hong Xiao, Hongwei Guo, Guang Yang, Runchao Zhao, Chen Yao et Rongqiang Liu. « Design of Multi-Wing Deployment Mechanism Based on Multiple Performance Indicators and Topology : Theoretical and Experimental Study ». Applied Sciences 14, no 24 (13 décembre 2024) : 11672. https://doi.org/10.3390/app142411672.
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The folding wing deployment mechanisms of aircraft are constrained by weight and space limitations, necessitating fewer actuators, multiple outputs, compact designs, and high efficiency. However, existing folding wing mechanisms often overlook the impact of performance in configuration design. Additionally, they struggle to achieve the synchronous unfolding of multiple wings using a single drive. This paper presents a design methodology for multi-wing deployment mechanisms based on configuration topology and multiple performance indicators. Specifically, seventeen configurations of multi-wing deployment mechanisms are developed based on functional requirements, along with expression methods for performance indicators, including compactness, mechanism stiffness, dynamic sensitivity, motion transmission, and joint transmission efficiency. The optimal configuration for the multi-wing deployment mechanism is identified utilizing the fuzzy comprehensive evaluation. Moreover, the transmission efficiency of multiple configurations is calculated across different scale parameters. Simulation analyses and prototype experiments are conducted to validate the design. The results indicate that the transmission efficiency of the optimized configuration consistently exceeds that of the other configurations. Maximum efficiencies surpass those of the other configurations by 2.4% and 5.7%. Importantly, this study introduces a quantitative expression method for multiple performance indicators at the configuration design stage. This approach enables the integration of various performance metrics with configuration designs. Overall, this research provides a novel approach for the innovative design of multi-wing deployment mechanisms in aircraft. Additionally, considering performance in the selection of mechanism configurations during engineering design offers valuable insights and potential applications.
3
Dijksman, E. A. « Assembling Complete Pole Configurations for (Over)Constrained Planar Mechanisms ». Journal of Mechanical Design 116, no 1 (1 mars 1994) : 215–25. http://dx.doi.org/10.1115/1.2919350.
Texte intégralRésumé :
The complete pole configuration of a planar n-link mechanism having one instantaneous degree of mobility, possesses (3n−4)/2 independent poles determining (n−2)2/2 remaining poles of the configuration. The dependency is demonstrated through Desargues’ Theorem and her generalizations. Simultaneously, pole configurations have been “elated” into three-dimensional point-lattices intersected by a plane. The insight obtained in these configurations allows the designer to find clues in building overconstrained linkage mechanisms meeting certain geometrical properties.
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Chen, Yan-song, I.-Ming Chen et Tyng Liu. « A design approach for multi-configuration hybrid transmission mechanisms ». Proceedings of the Institution of Mechanical Engineers, Part D : Journal of Automobile Engineering 234, no 12 (20 juin 2020) : 2744–58. http://dx.doi.org/10.1177/0954407020924981.
Texte intégralRésumé :
Several hybrid architectures have been widely used in hybrid electric vehicles. For example, power-split architecture brings seamless operation, while parallel architecture makes the internal combustion engine directly drive the wheel. To combine the advantages of various architectures, this study aims to develop a design approach to create a transmission mechanism that has multiple configurations and uses these configurations to achieve several hybrid architectures. First, this study standardized hybrid transmission mechanisms using the Function Power Graph; this powerful and intuitive tool inspired several elements and an element layout for the new mechanisms. Then, several configurations with up to five elements were enumerated and organized into the databases. Next, the mechanisms with multiple configurations and a limited number of clutching units (clutches or brakes) were evaluated, 10 of which were identified as the best group that provided five parallel configurations, two 2-motor electric vehicle configurations, and a power-split configuration. At the end of this paper, a novel hybrid transmission mechanism was developed as a demonstration. It provides higher power and torque at the output but there is no need to use the larger internal combustion engine or motor-generators. This mechanism also enables the internal combustion engine to drive in overdrive parallel architectures to avoid the loss in energy conversion when the power-split architecture is not required. As a result, after a designer specifies the desired hybrid configurations, follows the procedure, and uses the configuration databases built in this study, a novel hybrid transmission mechanism will be created.
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Kuo, Chin-Hsing, et Hong-Sen Yan. « On the Mobility and Configuration Singularity of Mechanisms With Variable Topologies ». Journal of Mechanical Design 129, no 6 (17 mai 2006) : 617–24. http://dx.doi.org/10.1115/1.2717230.
Texte intégralRésumé :
The mechanisms with variable topologies (MVTs) are usually changing their topological structures in accordance with the varying mobility and quasi-singular configurations. The mobility analysis and configuration singularity of MVTs are studied via screw theory in this paper. The configurations of MVTs are formulated by a set of variable combinations of screw coordinates. For the mobility analysis, two examples provided show that the proposed approach is adoptable for dealing with common MVTs. For the configuration singularity, the concepts of stationary configuration and uncertainty configuration are utilized to demonstrate the topology varying strategy of MVTs. The result in this work provides the theoretical basis and inspiration for the configuration synthesis and analysis of mechanisms with variable topologies.
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Yahlinskyi, V. P., S. S. Hutyria et V. V. Vovk. « AMBIGUITY AND SINGULARITY MECHANISMS OF PARALLEL STRUCTURE OF BIGLIDE TYPE ». Key title : Zbìrnik naukovih pracʹ Odesʹkoï deržavnoï akademìï tehnìčnogo regulûvannâ ta âkostì, no 1(22) (2023) : 45–52. http://dx.doi.org/10.32684/2412-5288-2023-1-22-45-52.
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The article deals with the issues of planning and obtaining shaping trajectories of the mechanisms of a parallel structure of the biglide type. The possibilities of forming functional trajectories of a biaxial two-coordinate biglide in the direct problem in the form of generalized coordinates of the degrees of freedom and the inverse problem in the form of gripper pole coordinates are considered. The conditions for the occurrence of ambiguity in the position of the mechanism in direct and inverse problems are revealed. To avoid ambiguity, it is proposed to control the process of forming a trajectory using an additional parameter. In the process of computer 3-D modeling, singular configurations of the biaxial bigglide mechanism with parallel guides were studied. Analytical models for the formation of trajectories are developed and kinematic conditions are proposed for avoiding locking processes in the mechanism in singular configurations. Singular configurations with quasi-zero and negative stiffness have been found for the mechanism of a parallel structure of the biglide type. Using the Lagrange principle of virtual (possible) displacements, analytical models of the generalized stiffness coefficients of the mechanism are obtained depending on the formed configuration. Configurations with quasi-zero stiffness correspond to zero values of the stiffness coefficients, and for negative stiffness, a characteristic transition through a singular configuration. Analytical expressions for the relative rigidities of the biglide mechanism are obtained and diagrams of their change for different configurations are constructed. The influence of the design parameters of the biglide on the value of the relative generalized stiffness of the entire mechanism has been studied. It has been established that within the range of configuration angle change from 0 to 12° and from 45° to 80°, the values of relative stiffness coefficients are much higher than within the range from 15° to 45°, which allows controlling the rigidity of the mechanism and having a positive effect on the positioning accuracy of the pole. biglide.
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Brunetti, Jacopo, Walter D’Ambrogio et Annalisa Fregolent. « Configuration-Dependent Substructuring as a Tool to Predict the Vibrational Response of Mechanisms ». Machines 10, no 12 (1 décembre 2022) : 1146. http://dx.doi.org/10.3390/machines10121146.
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Dynamic substructuring allows us to predict the dynamic behavior of mechanical systems built by linking together several subsystems, whose dynamic behavior is known. The classical formulation, originally conceived for invariant systems, was extended by the authors to include mechanical systems made by invariant subsystems that may be coupled in different configurations. A mechanism is a typical example of a mechanical system built by coupling together invariant subsystems; during its motion, it can take several configurations that significantly affect its vibrational behavior. Therefore, the configuration-dependent substructuring approach can provide meaningful insights into the dynamic behavior of the mechanism. In this paper, the proposed approach is exploited to evaluate the vibrational behavior of a three-point linkage, a widely used mechanism to connect agricultural tractors to operating machines, considering a significant range of operative configurations. The proposed substructuring approach is able to predict the frequency response functions, the natural frequencies and the mode shapes of the mechanism in a wide range of configurations.
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Kuo, Chin-Hsing, Jyun-Wei Su et Lin-Chi Wu. « An Algebraic Formulation for the Configuration Transformation of a Class of Reconfigurable Cube Mechanisms ». Mechanical Sciences 8, no 1 (12 avril 2017) : 101–9. http://dx.doi.org/10.5194/ms-8-101-2017.
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Abstract. This paper presents an algebraic strategy for formulating the configuration transformation of a special class of reconfigurable cube mechanism (RCM) made by 23 cyclically connected sub-cubes. The RCM studied here is kinematically equivalent to a spatial eight-bar linkage having eight transformable configurations. In this paper, the reconfiguration characteristics of the RCM are figured out first. Then, the initial configuration of the RCM is described by a joint-screw matrix, from which all the consecutive joint-screw matrices that represent the configuration transformation of the RCM can be derived. An illustrative example is provided to determine the eight joint-screw matrices of an RCM at an initial configuration. This reconfiguration formulation is further applied to enumerate all feasible topological configurations of such a special reconfigurable mechanism. The results show that, for such a special kind of reconfigurable cube mechanisms, there is only one feasible initial topological configuration for the RCM to perform a complete cycle of reconfiguration.
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Chen, Tzu-Hsia, et Long-Chang Hsieh. « The Design of Mold Clamping Mechanisms with Two Dead-Position Configurations ». Advances in Technology Innovation 5, no 1 (1 janvier 2020) : 33–44. http://dx.doi.org/10.46604/aiti.2020.4164.
Texte intégralRésumé :
Blow-molding machines are divided into two types: (1) rotary type blow-molding machine, and (2) linear type blow-molding machine. Good kinematic characteristics of mold clamping mechanism is the goal pursued by manufacturers of blow-molding machine. Traditionally, the mold clamping mechanism has only one dead-position configuration for the mold in the closed position. When the mold is in the open position, the mold clamping mechanism does not have dead-position configuration. This study focuses on the design of mold clamping mechanisms with two dead-position configurations when the mold is in open and closed positions. Firstly, with reference to the existing patents, based on the Yan's creative design methodology, four design concepts of mold clamping mechanisms are synthesized. Then, according to the studies on kinematics of mechanisms, three mold clamping mechanisms with two dead-position configurations are also synthesized. The results of this paper will enhance the research and development (R&D) capability of the mold clamping mechanisms to improve industrial competitiveness.
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WANG, JING, et CLÉMENT M. GOSSELIN. « PASSIVE MECHANISMS WITH MULTIPLE EQUILIBRIUM CONFIGURATIONS ». Transactions of the Canadian Society for Mechanical Engineering 28, no 2A (mai 2004) : 139–51. http://dx.doi.org/10.1139/tcsme-2004-0011.
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Krishnamurty, S., et David A. Turcic. « Branching Determination in Nondyadic Planar Multiloop Mechanisms ». Journal of Mechanical Design 114, no 2 (1 juin 1992) : 245–50. http://dx.doi.org/10.1115/1.2916938.
Texte intégralRésumé :
The paper presents the development of a sub-Jacobian based method for the identification and elimination of branch defects during synthesis in nondyadic planar multiloop mechanisms. Branching occurrences in a given mechanism can be recognized by the resulting changes in the configurations of one or more of the sets of three constraints that form the mechanism. Further, any such change in a constraint set configuration will be characterized by a corresponding change in the determinant sign of its sub-Jacobian matrix. Applying this method, branching can be eliminated during synthesis by identifying all such constraint sets for the mechanism and using the determinant signs of their sub-Jacobian matrices to maintain the mechanism’s original configuration.
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Lerbet, J., et M. Fayet. « Singularities of mechanisms and the degree of mobility ». Proceedings of the Institution of Mechanical Engineers, Part K : Journal of Multi-body Dynamics 217, no 2 (1 juin 2003) : 111–19. http://dx.doi.org/10.1243/146441903321898601.
Texte intégralRésumé :
The Kinematics, statics and dynamics of singular configurations of mechanisms are analysed. Using Lie group theory, the tangent cone at such a configuration is defined and calculated. It is clear that the structure of the cone is directly linked with one of Lie algebra. The statics and dynamics of singularity analysis are addressed, making it possible to apply the concept of the transitory degree of mobility.
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Kuźma, Dominika, et Piotr Zieliński. « Finite Length Effects on Switching Mechanisms in Chains of Magnetic Particles ». Magnetochemistry 6, no 4 (1 octobre 2020) : 47. http://dx.doi.org/10.3390/magnetochemistry6040047.
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Periodic systems of magnetic nanoparticles are now of interest as they support GHz spin waves. Their equilibrium configurations, switchable with the external magnetic field, are crucial for such applications. We study infinite and finite chains of particles of two shapes (i) ellipsoidal and (ii) rectangular stripes with long axes perpendicular to the chain axis. A variable magnetic field is applied parallel to the long axes. Micromagnetic simulations are compared with the corresponding discrete spin models (Stoner-Wohlfarth model, S-W). An antiferromagnetic configuration is the ground state for all the systems at vanishing field but a ferromagnetic configuration occurs when the field is strong enough. The switching of the infinite chains to the reversed ferromagnetic configuration proceeds directly for the ellipsoids and by an intermediate configuration, in which the magnetization within the particle is non-uniform, in the case of the stripes. The non-uniform configurations are well represented by tilted states in S-W model. Important differences are found in the finite analogs: the switching of ellipsoids becomes multistage and starts from the innermost particles relatively well reproduced with S-W model, whereas the reversal of the stripes, starts from the outermost particles and has no analog in S-W model. Practical consequences of the findings are discussed.
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binti Harun, Siti Fatimah, Mohd Fais bin Mansor et Norbahiah binti Misran. « Reconfigurable Reflectarray Antenna : Background, Classification and Configurable Mechanisms ». Jurnal Kejuruteraan 35, no 5 (30 septembre 2023) : 1249–64. http://dx.doi.org/10.17576/jkukm-2023-35(5)-24.
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Reflectarray antennas have emerged as one of the most suitable choice for 5G network base station antennas due to their ability to combine the advantages of parabolic reflectors and phased array antennas. These antennas offer a lightweight structure, high gain, and low impedance mismatch losses. High gain and low loss are crucial factors in ensuring the antenna delivers low latency and high-quality 5G radio signals. The application of 5G technology becomes more practical and efficient with the capability to adjust the functionality of a single 5G antenna or enable reconfiguration. This reconfigurable technique simplifies the multi-antenna systems and significantly reduces costs, making it more practical and systematic. Furthermore, this reconfigurability is particularly beneficial for satellite applications, as it allows for the reconfiguration of the signal in the event of satellite movement on the space. This paper aims to discuss the historical development of reconfigurable reflectarray antennas, focusing on the innovations in each configurable mechanism. The paper further explores the classification of configurations employed by this antenna, encompassing frequency configuration, radiation pattern, polarization, and hybrid configurations that integrate multiple existing configuration classifications. Finally, the research paper provides a discussion of the most recent research and innovations in the configurable mechanisms of reflectarray antennas.
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Zhu, Jialong, Chuang Shi, Xiaodong Fan, Xiaofei Ma, Hongwei Guo, Shikun Zheng et Rongqiang Liu. « Synthesis and Networking of Spaceborne Deployable Prismatic Antenna Mechanisms Based on Graph Theory ». International Journal of Aerospace Engineering 2024 (10 janvier 2024) : 1–19. http://dx.doi.org/10.1155/2024/4347716.
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Spaceborne deployable cylindrical antennas have broad application prospects in the fields of space earth observation and remote-sensing detection because of their significant advantages of ultralong aperture, high gain, and flexible beam scanning. As application requirements rapidly develop, a new type of spaceborne deployable cylindrical antenna mechanism with a large diameter and deployability is urgently needed. This paper presents an innovative design for a cylindrical deployable antenna mechanism based on 18R triangular prism elements based on graph theory. The correctness of the configuration is verified by developing a prototype. First, four kinds of nonoverconstrained 12-bar triangular prism-stabilized truss structure configurations and their corresponding topological diagrams are constructed. Second, based on graph theory, three types of 102 triangular prism-stabilized truss mechanism configurations that can be folded into linear mechanisms are derived. Third, the kinematic pair configuration is established to achieve a single-degree-of-freedom 7R2U9S triangular prism deployable unit. Fourth, combined with the geometric topology characteristics of the unit network, a triangular prism unit networking method is proposed, and a cylindrical network mechanism configuration based on 18R triangular prism units is obtained. A prototype was fabricated by 3D printing, and an expansion and retraction function test was conducted, which verified the correctness of the theoretical analysis in this paper. Finally, a new concept configuration for a parabolic cylindrical antenna is proposed. This paper provides a reference for the configuration of large-scale folding truss structures with unit expansion.
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Yu, S. L., W. D. Zhao, J. Chen, N. Wang et X. D. Cai. « Investigation of Flow Boiling Heat Transfer Mechanisms in Channels with Complex Wall Configurations ». Advances in Engineering Technology Research 12, no 1 (18 février 2025) : 1376. https://doi.org/10.56028/aetr.12.1.1376.2024.
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Flow boiling has numerous applications in many daily life and industrial fields due to its high heat transfer efficiency. By using the Lattice Boltzmann Method (LBM) with the pseudopotential model, coupled with the finite difference method to solve the temperature field, the flow boiling process of water in a 2D horizontal channel with complex configurations is simulated. The study investigates the impact of different factors such as wall configurations and fluid velocity on the flow and heat transfer processes. The results show that the more cavities and finer pillars in the wall structure, the higher the heat transfer efficiency. Increasing the flow velocity effectively promotes bubble detachment and enhances heat transfer efficiency. This study provides insights for channels configuration designs.
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Zhang, W. X., X. L. Ding et J. S. Dai. « Morphological synthesis of metamorphic mechanisms based on constraint variation ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 225, no 12 (22 août 2011) : 2997–3010. http://dx.doi.org/10.1177/0954406211408953.
Texte intégralRésumé :
A metamorphic mechanism can be considered as a mechanism set composed by multiple kinematic chains which have the ability to be transformed sequentially from one to another following specific rules in order to meet different requirements of tasks. The process of its configuration transformation results from the variation of constraints. A special classification approach of constraints is proposed based on its characteristic of multi-configuration. The basic modes to achieve configuration transformation of metamorphic mechanisms and the design principle of metamorphic kinematic pairs are further presented. Finally, a configuration synthesis methodology of the metamorphic mechanism is proposed based on a morphological matrix. The essence of this methodology is to realize variation and coupling of mechanisms in adjacent configurations by applying metamorphic kinematic joints according to the functions, constraints, and configuration sequence. The approach is verified by developing a vehicle that can convey materials with a metamorphic driving mechanism. This study provides a fundamental theory for the design of new metamorphic mechanisms.
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Varela-Vaca , Ángel Jesús, Rafael M. Gasca, Rafael Ceballos, María Teresa Gómez-López et Pedro Bernáldez Torres. « CyberSPL : A Framework for the Verification of Cybersecurity Policy Compliance of System Configurations Using Software Product Lines ». Applied Sciences 9, no 24 (8 décembre 2019) : 5364. http://dx.doi.org/10.3390/app9245364.
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Cybersecurity attacks affect the compliance of cybersecurity policies of the organisations. Such disadvantages may be due to the absence of security configurations or the use of default configuration values of software products and systems. The complexity in the configuration of products and systems is a known challenge in the software industry since it includes a wide range of parameters to be taken into account. In other contexts, the configuration problems are solved using Software Product Lines. This is the reason why in this article the framework Cybersecurity Software Product Line (CyberSPL) is proposed. CyberSPL is based on a methodology to design product lines to verify cybersecurity policies according to the possible configurations. The patterns to configure the systems related to the cybersecurity aspects are grouped by defining various feature models. The automated analysis of these models allows us to diagnose possible problems in the security configurations, reducing or avoiding them. As support for this proposal, a multi-user and multi-platform solution has been implemented, enabling setting a catalogue of public or private feature models. Moreover, analysis and reasoning mechanisms have been integrated to obtain all the configurations of a model, to detect if a configuration is valid or not, including the root cause of problems for a given configuration. For validating the proposal, a real scenario is proposed where a catalogue of four different feature models is presented. In this scenario, the models have been analysed, different configurations have been validated, and several configurations with problems have been diagnosed.
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Wang, Jianping, Youchao Wang, Boyan Chen, Xiaoyue Jia et Dexi Pu. « Trajectory Classification and Recognition of Planar Mechanisms Based on ResNet18 Network ». Algorithms 17, no 8 (25 juillet 2024) : 324. http://dx.doi.org/10.3390/a17080324.
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This study utilizes the ResNet18 network to classify and recognize trajectories of planar mechanisms. This research begins by deriving formulas for trajectory points in various typical planar mechanisms, and the resulting trajectory images are employed as samples for training and testing the network. The classification of trajectory images for both upright and inverted configurations of a planar four-bar linkage is investigated. Compared with AlexNet and VGG16, the ResNet18 model demonstrates superior classification accuracy during testing, coupled with reduced training time and memory consumption. Furthermore, the ResNet18 model is applied to classify trajectory images for six different planar mechanisms in both upright and inverted configurations as well as to identify whether the trajectory images belong to the upright or inverted configuration for each mechanism. The test results affirm the feasibility and effectiveness of the ResNet18 network in the classification and recognition of planar mechanism trajectories.
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Dai, Jian S., et John Rees Jones. « Matrix Representation of Topological Changes in Metamorphic Mechanisms ». Journal of Mechanical Design 127, no 4 (24 juillet 2004) : 837–40. http://dx.doi.org/10.1115/1.1866159.
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Metamorphic mechanisms form a class of mechanisms that has the facilities to change configuration from one kind to another with a resultant change in the number of effective links and mobility of movement. This paper develops formal matrix operations to describe the distinct topology of configurations found in a metamorphic mechanism and to complete transformation between them. A new way is hence introduced for modeling topological changes of metamorphic mechanisms in general. It introduces a new elimination E-elementary matrix together with a U-elementary matrix to form an EU-elementary matrix operation to produce the configuration transformation. The use of these matrix operations is demonstrated in both spherical and spatial metamorphic mechanisms, the mechanistic models taken from the industrial packaging operations of carton folding manipulation that stimulated this study.
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Zhang, Li, Yang Liu et Yongju Zhang. « An Improved Metamorphosis-Based Scheme of Feed Mechanism Using Configuration Synthesis ». Processes 10, no 12 (23 novembre 2022) : 2487. http://dx.doi.org/10.3390/pr10122487.
Texte intégralRésumé :
In this work, the principle of metamorphic mechanism is optimized for the product design based on variable topological structures. One metamorphic element consisting of kinematic pair and kinematic size is proposed firstly and a configuration synthesis strategy for feed mechanism is performed in term of the translocation, inversion and duplication variation methods. Metamorphic elements are obtained by decomposing the source metamorphic mechanism. A novelty configuration scheme based on constraint variation features is established by the solution of the constraint relationship of metamorphic elements, and three kinds of configurations are synthesized. Comparisons with kinematic performances between source mechanism and developed mechanism configurations are modelled by the kinematic simulation. Results demonstrate that the multiple types of metamorphic mechanisms can be successfully synthesized, and the demands of functional targets are satisfied completely.
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Chu, Chia-Chun, et Deng-Maw Lu. « THE SYNTHESIS OF THE PLANAR LINKAGES WITH SYMMETRICAL CONFIGURATIONS ». Transactions of the Canadian Society for Mechanical Engineering 40, no 5 (décembre 2016) : 971–79. http://dx.doi.org/10.1139/tcsme-2016-0080.
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The mechanisms that employ symmetrical configurations can be found in the steering mechanisms, double open refrigerator, roof boxes, and double open windows, among others. They are useful for some special applications with kinematic symmetry. There have been studies about the linkage synthesis, especially in the research of planar closed chains, from as early as 1960s. However, no study has focused on the symmetry of planar linkages. Thus, the purpose of this paper is to present a methodology to synthesize the configurations of planar linkages. The systematic methodology can be divided into structure synthesis, configuration synthesis and results produced from three major processes. Finally, four suitable results of up to six-bar linkages can be obtained, for example. The four results include one four-bar linkage and three six-bar linkages.
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Sun, Wei, Jianyi Kong et Liangbo Sun. « A holographic matrix representation of the metamorphic parallel mechanisms ». Mechanical Sciences 10, no 2 (12 août 2019) : 437–47. http://dx.doi.org/10.5194/ms-10-437-2019.
Texte intégralRésumé :
Abstract. Metamorphic mechanisms belong to the class of mechanisms that are able to change their configurations sequentially to meet different requirements. In this paper, a holographic matrix representation for describing the topological structure of metamorphic mechanisms was proposed. The matrix includes the adjacency matrix, incidence matrix, links attribute and kinematic pairs attribute. Then, the expanded holographic matrix is introduced, which includes driving link, frame link and the identifier of the configurations. Furthermore, a matrix representation of an original metamorphic mechanism is proposed, which has the ability to evolve into various sub-configurations. And evolutionary relationships between mechanisms in sub-configurations and the original metamorphic mechanism are determined distinctly. Examples are provided to demonstrate the validation of the method.
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Burneika, Linas. « Managing Changes in Product Configurations ». Solid State Phenomena 144 (septembre 2008) : 208–13. http://dx.doi.org/10.4028/www.scientific.net/ssp.144.208.
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In modern engineering environment all information about product is stored in the PDM (Product Data Management) system. These systems allow enumerated configurations of product by using mechanisms of BOM or versioning. However problems arise when product has a large number of configurations that are updated frequently. This is common situation in market of consumer goods. In the present paper this issue is addressed by extending an engineering configuration concept. An initial idea of engineering configurator is to have a product defined by generic BOM with all possible components. The BOM also includes a set of constrains, that define valid combinations of components. However it is difficult to maintain such generic BOM. This paper proposes an idea of BOM decomposition into simple and manageable units belonging to single product space. Decomposition is also performed in the domain of constrains. Configuration problem is split into independent sub-problems, which could be delegated to different engineers to work on, or to do maintenance. The resultant structure is easy to comprehend for engineer, because it follows a natural way of thinking during product design. Therefore, changes in configurations could be done much faster, less time is spend for verifications.
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Zarkandi, Soheil. « A new geometric method for singularity analysis of spherical mechanisms ». Robotica 29, no 7 (19 avril 2011) : 1083–92. http://dx.doi.org/10.1017/s0263574711000385.
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SUMMARYFinding singular configurations (singularities) has an important role during the design, trajectory planning, and control stages of mechanisms because in these configurations, the instantaneous kinematics is locally undetermined. In this paper, a systematic method is presented to obtain singular configurations of spherical mechanisms with input and output links. The method extends the use of instantaneous poles to singularity analysis of spherical mechanisms and offers geometric conditions for any type of singularities occurring in these mechanisms.
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Cademartori, Stefano, Carlo Cravero, Martino Marini et Davide Marsano. « CFD Simulation of the Slot Jet Impingement Heat Transfer Process and Application to a Temperature Control System for Galvanizing Line of Metal Band ». Applied Sciences 11, no 3 (27 janvier 2021) : 1149. http://dx.doi.org/10.3390/app11031149.
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A CFD model to simulate the cooling technique trough slot jet impingement has been developed. Such a technique has been tested on an existing vertical galvanizing industrial line, which initially envisaged a round jet configuration, the subject of a previous work. Two different slot jet configurations have been simulated and compared to the pre-existing one, in order to provide design information for a possible new jet cooler after exploring different solutions. The numerical model has been appropriately calibrated and validated by comparing it with experimental measurements from a literature case. At first, a single slot jet configuration was simulated through a 2D model, then multi slot configurations were calculated using 3D models. Different turbulence models were compared to select the best candidate for the CFD approach. Finally, several configurations with different slots numbers and jet-wall distances were considered. It was possible to understand the physical mechanisms underlying this cooling technique and to be able to select the most promising configuration for the reference industrial cooling process.
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Wang, Luofeng, et Renliang Chen. « Handling Qualities Assessment and Discussion for Helicopter with Slung Load Systems Utilizing Various Sling Configurations ». Aerospace 11, no 9 (31 août 2024) : 711. http://dx.doi.org/10.3390/aerospace11090711.
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Sling configurations significantly influence the coupled dynamics of the helicopter with slung load system (HSLS), resulting in alterations to handling qualities (HQs) that remain inadequately understood. This study introduces a computer-oriented, generalized method for constructing the HSLS model with various sling configurations. To evaluate the HQs of 1-point, 2-point, and 4-point sling configurations, both the stability and response criteria outlined in ADS-33E and a newly proposed criterion for slung loads towards the updated ADS-33F were employed. Modal analysis was conducted to elucidate the coupled mechanisms of the HSLS under different sling configurations. The findings reveal that the dynamics of the main rotor can attenuate the lateral swing motions of the load in the 4-point sling configuration. While multiple-point sling configurations can enhance the helicopter’s bandwidth, they also amplify the magnitude notch in the helicopter’s response. Nevertheless, when a larger hook distance is employed, the notch frequency is sufficiently distant from the load swing bandwidth, leading to a reduced degradation in HQs. A 4-point configuration with lateral and longitudinal hook distances equal to twice the width and length of the slung load is recommended in practice to achieve sufficient swing stability and mitigate HQ degradation.
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Salih, Khalid A. M., Ismail Amin Ali et Ramadhan J. Mstafa. « Impact of Video Motion Content on HEVC Coding Efficiency ». Computers 13, no 8 (18 août 2024) : 204. http://dx.doi.org/10.3390/computers13080204.
Texte intégralRésumé :
Digital video coding aims to reduce the bitrate and keep the integrity of visual presentation. High-Efficiency Video Coding (HEVC) can effectively compress video content to be suitable for delivery over various networks and platforms. Finding the optimal coding configuration is challenging as the compression performance highly depends on the complexity of the encoded video sequence. This paper evaluates the effects of motion content on coding performance and suggests an adaptive encoding scheme based on the motion content of encoded video. To evaluate the effects of motion content on the compression performance of HEVC, we tested three coding configurations with different Group of Pictures (GOP) structures and intra refresh mechanisms. Namely, open GOP IPPP, open GOP Periodic-I, and closed GOP periodic-IDR coding structures were tested using several test sequences with a range of resolutions and motion activity. All sequences were first tested to check their motion activity. The rate–distortion curves were produced for all the test sequences and coding configurations. Our results show that the performance of IPPP coding configuration is significantly better (up to 4 dB) than periodic-I and periodic-IDR configurations for sequences with low motion activity. For test sequences with intermediate motion activity, IPPP configuration can still achieve a reasonable quality improvement over periodic-I and periodic-IDR configurations. However, for test sequences with high motion activity, IPPP configuration has a very small performance advantage over periodic-I and periodic-IDR configurations. Our results indicate the importance of selecting the appropriate coding structure according to the motion activity of the video being encoded.
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Bonev, Ilian A., Dimiter Zlatanov et Cle´ment M. Gosselin. « Singularity Analysis of 3-DOF Planar Parallel Mechanisms via Screw Theory ». Journal of Mechanical Design 125, no 3 (1 septembre 2003) : 573–81. http://dx.doi.org/10.1115/1.1582878.
Texte intégralRésumé :
This paper presents the results of a detailed study of the singular configurations of 3-DOF planar parallel mechanisms with three identical legs. Only prismatic and revolute joints are considered. From the point of view of singularity analysis, there are ten different architectures. All of them are examined in a compact and systematic manner using planar screw theory. The nature of each possible singular configuration is discussed and the singularity loci for a constant orientation of the mobile platform are obtained. For some architectures, simplified designs with easy to determine singularities are identified.
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Mewes, JC, SA Ahmed et HJM Vrijhoef. « How do integrated care programmes work for patients with cardiovascular disease, chronic obstructive pulmonary disease, depression, diabetes and multi-morbidity ? A rapid realist review ». International Journal of Care Coordination 21, no 3 (17 juillet 2018) : 87–97. http://dx.doi.org/10.1177/2053434518788593.
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Background In previous years, many multi-faceted initiatives have been set up to improve outcomes for people with chronic diseases. Evaluation studies about the (cost-)effectiveness of these integrated care programs showed heterogeneity in outcomes. Hence, it has been suggested to use realist evaluation for the evaluation of integrated care programmes. Thus, our aim was to gain insight into whether and how existing integrated care programmes work for people with cardiovascular disease, chronic obstructive pulmonary disease, depression, diabetes and multi-morbidity, and under what conditions within the Dutch healthcare setting. Methods A rapid realist review was conducted to identify the context and mechanisms that are associated with the outcomes of integrated care programmes. From a selection of systematic reviews and meta-analyses and Dutch literature, data on the context, mechanisms and outcomes of integrated care programmes were extracted. The data were analysed by placing the extracted variables in context-mechanism-outcome configurations which showed their interrelatedness. A panel of executives from Dutch care groups assessed the face validity of the context-mechanism-outcome configurations. Results Based on the existing literature, context-mechanism-outcome configurations were compiled for all five diseases. Some configurations could be filled with more detail than others, with the configuration of integrated care for people with diabetes being the most complete. Context-mechanism-outcome configurations were completed and confirmed by executives from Dutch care groups. Conclusion The configurations together with the identified factors in them reveal the underlying preliminary program theories of integrated care programmes. These theories need to be tested in further research.
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Chen, Xiaoyan, Ting Wang, Yan Liu et Zixin Dou. « Configurational Path to Collaborative Innovation in Large and Complex Construction Projects ». Buildings 14, no 1 (2 janvier 2024) : 117. http://dx.doi.org/10.3390/buildings14010117.
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Collaborative innovation contributes to sustainable development in many industries. Although there is a growing literature on collaborative innovation, it is still unclear whether and how configurations of drivers affect collaborative innovation in large and complex construction projects (hereafter megaprojects). This research adopts fuzzy-set qualitative comparative analysis (fsQCA) to explore multiple conjunctural causations of collaborative innovation in megaprojects. The findings show that four equifinal solutions can influence collaborative innovation in megaprojects, i.e.: “system innovation-oriented” (configuration 1), “radical innovation-oriented” (configuration 2), “second-tier supplier oriented” (configuration 3), and “modular or architectural innovation-oriented” (configuration 4). This study contributes to explaining the mechanisms regarding how configurations of drivers contribute to collaborative innovation in megaprojects. It also contributes to the development of collaborative innovation research in a construction project context. The research findings provide construction project managers with four useful suggestions for promoting collaborative innovation in megaprojects.
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Ma, Kun, Hongwei Ma et Haibo Tian. « Kinematic analysis of a novel 2-PrRS-PR(P)S metamorphic parallel mechanism ». Advances in Mechanical Engineering 11, no 11 (novembre 2019) : 168781401988977. http://dx.doi.org/10.1177/1687814019889776.
Texte intégralRésumé :
Lower mobility parallel mechanisms have been developed in different structures and widely applied in industry, but still have disadvantages in various tasks and functional requirements. A 2-PrRS-PR(P)S metamorphic parallel mechanism with two working configurations and a transiting configuration is presented. First, the architecture and the way of metamorphosis about the mechanism are described in detail. The mobility of the metamorphic parallel mechanism is obtained with screw theory. Furthermore, the parasitic motions in different configurations are derived based on the geometry constraint conditions. Both the inverse kinematic problem and forward kinematic problem of the mechanism are investigated by the closed-loop equation and validated via numerical examples. Then, the velocity and acceleration in two working configurations are obtained by the derivation of the inverse kinematic problem. Finally, the reachable orientation workspaces are discussed using the three-dimensional search method in different configurations. A comparison with the 3-PRS PM without metamorphic mechanism in workspace is presented and an example of the metamorphic parallel mechanism in robotic supporting leg is presented. The above analyses provide theoretical foundations for application of this mechanism.
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Chahed, Hamza, et Andreas Kassler. « TSN Network Scheduling—Challenges and Approaches ». Network 3, no 4 (16 décembre 2023) : 585–624. http://dx.doi.org/10.3390/network3040026.
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Time-Sensitive Networking (TSN) is a set of Ethernet standards aimed to improve determinism in packet delivery for converged networks. The main goal is to provide mechanisms that enable low and predictable transmission latency and high availability for demanding applications such as real-time audio/video streaming, automotive, and industrial control. To provide the required guarantees, TSN integrates different traffic shaping mechanisms including 802.1Qbv, 802.1Qch, and 802.1Qcr, allowing for the coexistence of different traffic classes with different priorities on the same network. Achieving the required quality of service (QoS) level needs proper selection and configuration of shaping mechanisms, which is difficult due to the diversity in the requirements of the coexisting streams under the presence of potential end-system-induced jitter. This paper discusses the suitability of the TSN traffic shaping mechanisms for the different traffic types, analyzes the TSN network configuration problem, i.e., finds the optimal path and shaper configurations for all TSN elements in the network to provide the required QoS, discusses the goals, constraints, and challenges of time-aware scheduling, and elaborates on the evaluation criteria of both the network-wide schedules and the scheduling algorithms that derive the configurations to present a common ground for comparison between the different approaches. Finally, we analyze the evolution of the scheduling task, identify shortcomings, and suggest future research directions.
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Shen, Zhaohua, Xuelin Yang, Shan Wu, Huayang Huang, Xiaolan Yan, Ning Tang, Fujun Xu et al. « Mechanism for self-compensation in heavily carbon doped GaN ». AIP Advances 13, no 3 (1 mars 2023) : 035026. http://dx.doi.org/10.1063/5.0133421.
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Heavy carbon (C) doping is of great significance for semi-insulating GaN in power electronics. However, the doping behaviors, especially the atomic configurations and related self-compensation mechanisms, are still under debate. Here, with the formation energy as the input parameter, the concentrations of C defects with different atomic configurations are calculated by taking the configurational entropy into account. The result shows that the concentrations of tri-carbon complexes (CNCiCN, where Ci refers to interstitial carbon) and dicarbon complexes (CNCGa) cannot be neglected under heavy doping conditions. The concentration of CNCiCN can even exceed that of CN at sufficiently high doping levels. Especially, we suggest that it is the tri-carbon complex CNCiCN, instead of the commonly expected CGa, that acts as the self-compensation centers in semi-insulating GaN under heavy C doping conditions. The results provide a fresh look on the long-standing problem about the self-compensation mechanisms in C doped GaN.
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Yan, H. S., et F. C. Chen. « A METHODOLOGY FOR THE CONFIGURATION SYNTHESIS OF MACHINING CENTRES ». Transactions of the Canadian Society for Mechanical Engineering 21, no 2 (juin 1997) : 123–40. http://dx.doi.org/10.1139/tcsme-1997-0009.
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The purpose of this paper is to present a design methodology for the configuration synthesis of machining centres with tool change mechanisms to meet required topology and motion requirements. This methodology is computerized and the machining centres with tool change mechanisms of up to ten links are synthesized. As the result the minimum number of links of the mechanism of machining centres is 8 and the numbers of configurations of machining centres with 8, 9 and 10 links are 75, 331 and 793, respectively. Furthermore, this work provides a systematic approach for synthesizing spatial open-type mechanisms with motion requirements.
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Kumar, V. « Instantaneous Kinematics of Parallel-Chain Robotic Mechanisms ». Journal of Mechanical Design 114, no 3 (1 septembre 1992) : 349–58. http://dx.doi.org/10.1115/1.2926560.
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This paper addresses the instantaneous kinematics of robotic manipulators which have an in-parallel scheme of actuation. Hybrid geometries which require both serial and parallel actuation are also considered. Multifingered grippers, walking vehicles, and multiarm manipulation systems in addition to robot arms with a parallel structure can be included in this broad category. The direct and inverse kinematics (and statics) of these devices is discussed with particular attention to applications in control. An analytical method based on screw system theory for obtaining transformation equations between joint and end-effector coordinates is described. Special configurations in which the end-effector gains or loses a degree of freedom, which are also known as geometric singularities, are an important consideration in this study. This is because the number of special configurations or singularities in the workspace is far more for in-parallel manipulators than that for serial manipulators. The special configurations for a planar dual-arm manipulation system, which can be kinematically modeled as a 5-R linkage, are discussed in some detail as an example.
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Luo, Ji Man, Guang Qi Cai, X. Chen, B. J. Yang et W. Huang. « A New Method of Structural Synthesis about the Partly-DOF Parallel Robot Mechanisms Based on the Screw Theory ». Key Engineering Materials 315-316 (juillet 2006) : 425–29. http://dx.doi.org/10.4028/www.scientific.net/kem.315-316.425.
Texte intégralRésumé :
In this paper, based on some disciplinarians about the configuration design of Parallel Robot Mechanisms (PRM), the theory bases was established for parallel structural configuration design by developing different types of the partly degrees of freedom (DOF) parallel configuration designs. The new method to synthesize the partly DOF parallel mechanisms, called constraint accession, is provided to the classification of kinematical chains by use of screw theory. The active kinematical chains control the necessary DOF and the passive kinematical chains control the needless ones. In this paper, the relevant active and passive kinematical chains are put forward and the constraint chains are classified in detail. It is demonstrated by an example that new configurations can be obtained by assembling different kinematical limbs.
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Jensen, Brian D., et Larry L. Howell. « Identification of Compliant Pseudo-Rigid-Body Four-Link Mechanism Configurations Resulting in Bistable Behavior ». Journal of Mechanical Design 125, no 4 (1 décembre 2003) : 701–8. http://dx.doi.org/10.1115/1.1625399.
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Bistable mechanisms, which have two stable equilibria within their range of motion, are important parts of a wide variety of systems, such as closures, valves, switches, and clasps. Compliant bistable mechanisms present design challenges because the mechanism’s energy storage and motion characteristics are strongly coupled and must be considered simultaneously. This paper studies compliant bistable mechanisms which may be modeled as four-link mechanisms with a torsional spring at one joint. Theory is developed to predict compliant and rigid-body mechanism configurations which guarantee bistable behavior. With this knowledge, designers can largely uncouple the motion and energy storage requirements of a bistable mechanism design problem. Examples demonstrate the power of the theory in bistable mechanism design.
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Huang, Bo, Minghui Hu, Li Zeng, Guangshun Fu et Qinglong Jia. « Design Method for Hybrid Electric Vehicle Powertrain Configuration with a Single Motor ». Sustainability 14, no 13 (5 juillet 2022) : 8225. http://dx.doi.org/10.3390/su14138225.
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Existing design methods for hybrid power system configurations obtain new solutions based on experience, structure improvement or optimization, exhaustive searching, and the screening of schemes at the expense of less innovation and less efficiency. Furthermore, these methods lack mechanisms involving automotive theory to guide powertrain configuration design. In this study, a design method of configuration with a single motor based on basic schemes of speed and torque decoupling was proposed from the perspective of the hybrid electric vehicle fuel-saving mechanism. First, the coupling characteristics of speed and torque in the basic scheme were analyzed from four perspectives. Thereafter, new configurations that meet operation requirements were derived via configuration reconstruction, which combined the better basic schemes with brakes, clutches, and transmissions. A multidimensional evaluation and screening method based on dynamic performance, economic performance, and adaptability was built. A comparison of S-4 with Toyota Hybrid System, which was performed to demonstrate the feasibility of the design method, revealed that both configurations perform similarly in terms of economic performance, but the dynamic performance of the S-4 is greater by approximately 50%. The times required to attain 100 km/h from 0 km/h for THS and S-4 are 13.5 s and 6.69 s, respectively.
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WANG, Yuxin. « Bifurcation property and persistence of configurations for parallel mechanisms ». Science in China Series E 46, no 1 (2003) : 49. http://dx.doi.org/10.1360/03ye9005.
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Smulders, Frido E., Harry Boer, Poul H. K. Hansen, Ebbe Gubi et Kees Dorst. « Configurations of NPD - Production Interfaces and Interface Integration Mechanisms ». Creativity and Innovation Management 11, no 1 (mars 2002) : 62–73. http://dx.doi.org/10.1111/1467-8691.00237.
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Zlatanov, D., R. G. Fenton et B. Benhabib. « Identification and classification of the singular configurations of mechanisms ». Mechanism and Machine Theory 33, no 6 (août 1998) : 743–60. http://dx.doi.org/10.1016/s0094-114x(97)00053-0.
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Xiao, Chengli, Timothy P. McNamara, Shaozheng Qin et Weimin Mou. « Neural mechanisms of recognizing scene configurations from multiple viewpoints ». Brain Research 1363 (décembre 2010) : 107–16. http://dx.doi.org/10.1016/j.brainres.2010.09.068.
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Xu, Yundou, Jiantao Yao et Yongsheng Zhao. « Type synthesis of spatial mechanisms for forging manipulators ». Proceedings of the Institution of Mechanical Engineers, Part C : Journal of Mechanical Engineering Science 226, no 9 (5 janvier 2012) : 2320–30. http://dx.doi.org/10.1177/0954406211433246.
Texte intégralRésumé :
In this study, a systematic method is proposed to synthesize the parallel and hybrid serial–parallel mechanisms for the forging manipulators based on the screw theory. First, several typical configurations of five-degrees-of-freedom parallel mechanism for the forging manipulators are synthesized, and they are all non-overconstrained mechanisms. Then, two kinds of hybrid serial–parallel mechanisms for the forging manipulators with the advantages of motion decoupling are constructed, which are also not overconstrained. The configurations obtained in this study would provide more type selection for the heavy-duty forging manipulators in engineering.
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Sousa, Pedro. « A Framework for Highly Reconfigurable P2P Trackers ». Journal of Communications Software and Systems 9, no 4 (22 décembre 2013) : 236. http://dx.doi.org/10.24138/jcomss.v9i4.144.
Texte intégralRésumé :
The increasing use of Peer to Peer (P2P) applications,usually ruled by selfish behaviors, is posing new challengesto the research community. As contributions of this work we firstly devise a general framework underpinning the development of highly reconfigurable P2P trackers. Following that, a novel tracker architecture is proposed and several illustrative and enhanced tracker configurations are described. As result, the devised solution turns possible that flexible, programmable and adaptive peer selection mechanisms can be introduced at the P2P application level.The proposed solution assumes the general framework of one of the most popular P2P solutions, in this case a BitTorrent-like approach. As illustrative examples of the proposed framework capabilities, several straightforward and easy to deploy tracker configuration examples are presented, including methods for qualitative differentiation of swarm peers and advanced P2P Traffic Engineering mechanisms fostering the collaboration efforts between ISPs and P2P applications. Both the framework and the devised tracker configurations are validated resorting tosimulation experiments.
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Lyon, S. M., P. A. Erickson, M. S. Evans et L. L. Howell. « Prediction of the First Modal Frequency of Compliant Mechanisms Using the Pseudo-Rigid-Body Model ». Journal of Mechanical Design 121, no 2 (1 juin 1999) : 309–13. http://dx.doi.org/10.1115/1.2829459.
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The pseudo-rigid-body modeling technique is used to simplify the nonlinear analysis of compliant mechanisms. This paper presents the first work that investigates the possibility of using the pseudo-rigid-body model to predict the first modal response of compliant mechanisms. Four different configurations of the parallel-guiding mechanism are modeled and tested, as well as two configurations of compliant straight-line mechanisms. The model predictions of the first natural frequencies were compared with experimental results for all six mechanism configurations. The model predictions are within 9 percent of the experimental results for all cases.
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Sousa, Pedro, Vitor Pereira, Paulo Cortez, Miguel Rio et Miguel Rocha. « A Framework for Improving Routing Configurations using Multi-Objective Optimization Mechanisms ». Journal of Communications Software and Systems 12, no 3 (13 mars 2017) : 145. http://dx.doi.org/10.24138/jcomss.v12i3.79.
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IP networks are nowadays well established technologiesbeing used to support a myriad of applications and services,thus assuming a crucial role in todays telecommunication systems. Nevertheless, such infrastructures usually require network administrators to perform a wide set of complex planning and management tasks trying to attain adequate network configurations. Many of such management tasks can be mathematically formulated as NP-hard optimization problems, sometimes involving several objective functions. In this context, this work explores and demonstrates the potential of using computational intelligence methods as optimization engines to tackle complex network optimization problems. In particular, Multi-objective Evolutionary Algorithms (MOEAs) are used to attain near-optimal link state routing configurations robust to distinct operational conditions. As result, network administrators will be provided with a set of alternative routing configurations representing distinct tradeoffs between the considered optimization goals. The robustness of the proposed methods is illustrated by presenting several multiobjective optimization examples able to improve the performance and resilience levels of a network infrastructure. In this perspective, this work presents a contribution for this research area by proposing specific MOEAs based optimization methods able to improve network routing configurations. Furthermore, the devised methods are also integrated in a freely available Traffic Engineering optimization framework able to be used by network administrators interested in improving the routing configurations of their network infrastructures.
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Juárez-Campos, Ignacio, Diego A. Núñez-Altamirano, Lucia Márquez-Pérez, Leonardo Romero-Muñoz et Beatriz Juárez-Campos. « Hexapod with legs based on Peaucellier–Lipkin mechanisms ». International Journal of Advanced Robotic Systems 15, no 4 (1 juillet 2018) : 172988141879592. http://dx.doi.org/10.1177/1729881418795929.
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This article describes the way in which six nontraditional legs collaborate to provide locomotion to a walking machine when it moves along a path. Such legs are based on the one-degree-of-freedom Peaucellier–Lipkin mechanism, which was modified by the addition of four degrees of freedom. Such five-degree-of-freedom legs have the ability to adapt their postures according to the center of rotation around of which the machine walks. The attributes and abilities of the hexapod are expressed by means of a mathematical framework, which grants the spatial description and required joint variables, according to a specific task, resulting in the configuration of its legs for a particular path planning. Additionally, the article presents an illustrative example describing a detailed procedure concerning the configurations and collaboration of their legs according to an imposed center of rotation around of which the six-legged robot walks.
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Sandor, George N., Yongxian Xu et Tzu-Chen Weng. « On the elimination of branching in the synthesis of spatial single-loop mechanisms with lower pairs ». Robotica 6, no 2 (avril 1988) : 149–54. http://dx.doi.org/10.1017/s0263574700003969.
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SUMMARYA single-loop spatial mechanism kinematically becomes an open robot, if we separate the grounded joint of the input link which may then be considered as the end effector of the robot. Any position of the end-effector within the workspace of such an open robot can be reached via a number of different configurations of the links. These configurations are called “branches” of the open robot for that particular position of the end effector.If the open robot is now stretched to a limiting position by a force exerted on the end effector, all the possible branches of the mechanism approach each other. When they become coincident, they form the “limiting configuration”. Any two related branches are at opposite sides of the limiting configuration. From the relationship between the links in th elimiting configuration and in related branches, conditions for aviodance of branching of the original closed-loop mechanism can be obtained. This is necessary in order to assure that a set of consistent relative displacements are specified for the open robot to move displacements are specified for the open robot to move toward the desired end-effector position without jumping from one branch to another. As for the closed-loop mechanism, open robot branching aviodance ensures that a desired sequence of positions of a particular floating link in the loop will be generated without changing the branch of the link configuration.In this paper, the above approach is applied to RSSR, RRSC, RRSRR, RRRRRRR and RPCRRR spatial closed-loop motion-generator mechanisms and the corresponding conditions for aviodance of branching in the synthesis of the mechanisms are derived.
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Reinholtz, Charles F., George N. Sandor et Joseph Duffy. « Branching Analysis of Spherical RRRR and Spatial RCCC Mechanisms ». Journal of Mechanisms, Transmissions, and Automation in Design 108, no 4 (1 décembre 1986) : 481–86. http://dx.doi.org/10.1115/1.3258759.
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Most mechanisms can be assembled in two or more distinct configurations for a given position of the input link. Each distinct configuration is called a branch. When the prescribed positions of a synthesized mechanism lie on more than one branch, the mechanism is said to have branching problems or to suffer from “branch defect.” Usually, branching problems will render a mechanism unsuitable for the design task because the mechanism must be moved to the other branch during the course of motion. In most cases, this would require disassembly and reassembly of the mechanism. In this paper, conditions are developed for avoiding the branching problem in the spherical RRRR and spatial RCCC mechanisms. These conditions are ideally suited for incorporation into an optimization scheme as constraints because they do not require iterative calculations or a position analysis of the mechanism.