Journal articles on the topic 'Load Path Theory'
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1
Qiu, Gong An, Guoan Zhang, Xiao Ge Zhang, and Min Liu. "Safety Information Dissemination Path Prediction in High-Density Vehicular Wireless Networks." Advanced Materials Research 655-657 (January 2013): 1770–73. http://dx.doi.org/10.4028/www.scientific.net/amr.655-657.1770.
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Many safety applications needed safety warning information to be disseminated to all vehicles in an area quickly. A path prediction model was built from the fused evidences by evidence theory, in which the basic probability assignment function of the local load and the old path load could be achieved using fuzzy set. And the loads became the evidences of the dissemination path prediction respectively. The prediction result with the maximal confidence was regarded as the quasi-real-time dissemination path load. Simulations show that the average end-to-end delay of safety information under heavy load with path prediction is less than the half of the delay without path prediction. However, the average packets loss rate of two schemes is almost the same.
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Bai, Xin Lei, Li Ping Guo, and Liang Ze Liu. "Optimization Scheme of Load Transferring Path for Distribution Network." Applied Mechanics and Materials 494-495 (February 2014): 1656–59. http://dx.doi.org/10.4028/www.scientific.net/amm.494-495.1656.
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For the power distribution network load transferring path optimization problem, this paper focuses on optimization scheme of load transferring path based on the fast non-dominated storing genetic algorithm (NSGA-II) with elitist strategy, this proposed method can avoid the selection of weight and the preference of the solution, and the solution sets can highlight the essence of optimization problems, then the fuzzy theory and the entropy weight are employed to extract the comprehensive optimal solution. IEEE33 node system simulation results verify the effectiveness of the model and algorithm.
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Jie Gao and Li Zhang. "Load-balanced short-path routing in wireless networks." IEEE Transactions on Parallel and Distributed Systems 17, no. 4 (April 2006): 377–88. http://dx.doi.org/10.1109/tpds.2006.49.
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Gebhardt, Clemens, and Michael Kaliske. "Reliable simulation of timber structures by combined load and displacement control." Engineering Computations 32, no. 3 (May 5, 2015): 766–78. http://dx.doi.org/10.1108/ec-04-2014-0069.
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Purpose – The purpose of this paper is to propose a path-finding algorithm to solve problems with an arbitrary load-displacement relationship which results from geometrical and material nonlinear models to simulate e.g. timber structures realistically. Design/methodology/approach – A method using combined load and displacement control for the Newton method along with path-characterising measures and sub-incremention is introduced. A path-related stiffness measure is used to identify the situation when it is necessary to select the displacement control and chose the best degree of freedom as a parameter instead of the load factor. The nonlinearity index extracts information about the convergence behaviour during one incremental step. Together with the reduction of the load increments it avoids leaving the equilibrium path. Findings – The method is discussed based on numerical examples with highly nonlinear behaviour. It is capable to solve systems with decreasing load capacity and snap-back effects. Originality/value – The algorithm combines load and displacement control and adaptively choses the method and the corresponding degree of freedom and cares for reliable path following.
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Yang, Chao, Yansong Wang, Hui Guo, Jiang Lv, Ningning Liu, and Hongzhong Qi. "Vibration load and transfer path identification of vehicle using inverse matrix method based on singular value decomposition." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 234, no. 6 (November 22, 2019): 1703–13. http://dx.doi.org/10.1177/0954407019887887.
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Based on the theory of inverse transfer matrix, a novel method for simultaneous load identification of vehicle vibration is presented in this paper. Some response, excitation, reference points (called key points) and their transfer paths, which have severe effects on the vibration of a whole vehicle, are defined. The transfer functions among the key points are measured by experiments, and thereby a transfer function matrix of vehicle vibration is established. To solve ill-conditioning problem in the transfer function matrix, the methodology of singular value decomposition is introduced into matrix inversion in the excitation load identification. To reduce the identification error, four transfer function matrices with different reference points and condition numbers are selected and discussed. The results show that the more the reference points are, the smaller the condition number of transfer function matrix is, the higher the accuracy of excitation load identification. The transfer function matrix with minimum condition number is used to identify the excitation loads at the vehicle key points. Experimental verifications suggest that the newly proposed method is effective and feasible for excitation load identification of vehicle vibration. Using the identified excitation loads, furthermore, the vibration causes of the steering wheel and seat rail are obtained, which is helpful for improving vibration performance of the sample vehicle. In applications, the excitation load identification method proposed in this paper may be applied not only to other types of vehicle, but also to other complex electromechanical products for load identification in engineering.
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Liang, Ke, and Qin Sun. "Koiter’s Reduction Finite Element Method for Nonlinear Stability Analysis of Thin-Walled Shells." International Journal of Computational Methods 17, no. 01 (September 30, 2019): 1843004. http://dx.doi.org/10.1142/s0219876218430041.
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Thin-walled structures are widely used in aeronautical and aerospace engineering. Conical and cylindrical shells structures, under axial compression, are prone to failure by buckling and typically show a snap-back phenomenon in the end-shortening curve. Path-following technologies based on Newton-type methods have difficulties to trace reliably the snap-back response due to the extremely sharp turning angle near the limit point. In this paper, a Koiter’s reduction finite element method, termed the Koiter–Newton (KN) method, is presented to trace reliably the post-buckling path of cylinders and cones considering either linear buckling modes or dimples from lateral perturbation loads as geometric imperfection. A robust algorithm based on the bifurcation-detection technique is applied during the solution of the reduced order model to achieve a successful path-tracing. The numerical results presented reveal that the nonlinear prediction obtained from Koiter’s perturbation theory at the unloaded state of the structure is numerically accurate up to the buckling load and the initial post-buckling path.
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Yang, Bin, Qin Shou Huang, Ping Liang, and Hua Xu. "Simulation of Reflective Crack Propagation Path in Asphalt Overlay under the Partial Wheel Load." Advanced Materials Research 189-193 (February 2011): 2001–4. http://dx.doi.org/10.4028/www.scientific.net/amr.189-193.2001.
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Partial wheel load is one of the main causes that lead to shear-type reflective crack of asphalt overlay in the old cement concrete pavement. Based on the theory of fracture mechanics and finite element method, this paper focuses on the numerical simulation of the reflective crack propagation path in asphalt overlay under the partial wheel load. Calculation result and analysis show that reflective crack partially expands upwards at the side of wheel load under the effect of partial wheel load with a sequential increase of crack propagation length. As the crack propagation length increases, stress intensity factors grow rapidly in the early period, and then increase by degrees slowly and, in the later period, the amplitude grows increasingly. Stress and strain fields enhance as the reflective crack increases upwards and the crack propagation angle expands gradually with the increase of reflective crack propagation length.
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He, Longlong, Zhifang Liu, Junjie Gu, Jinliang Wang, and Kunfa Men. "Fatigue Crack Propagation Path and Life Prediction Based on XFEM." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 737–43. http://dx.doi.org/10.1051/jnwpu/20193740737.
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Based on the theory of linear elastic fracture mechanics, the relationships between material constants c3, c4 required in Abaqus and constants C, m in Paris formula are derived. Then extended finite element method (XFEM) of Abaqus software is used to is used to predict the crack propagation path and life of the plate with center inclined through crack and typical stiffened wing spar with initial crack under the constant amplitude fatigue load. The results show that the predicted crack propagation path is in good agreement with the experimental results, and the crack propagation life error is less than 6.3%. It also shows that this method can accurately predict the fatigue crack growth path and life of two-dimensional and three-dimensional complex structures under constant amplitude loads. This study can provide an effective way for damage tolerance analysis of structures and has certain engineering application value.
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Zhang, Jun Ping, Ai Rong Liu, Gang Wu, and Ke Zeng. "Study on Operating Vehicle Load Limit of Sub-Health Bridge." Advanced Materials Research 163-167 (December 2010): 3369–75. http://dx.doi.org/10.4028/www.scientific.net/amr.163-167.3369.
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Depending on the actual service condition of sub-health bridge, the following investigation is carried out: 1)The concept of damage limit state is proposed, from which the subject of the serviceability carrying capacity is revealed, then the evaluation path of serviceability carrying capacity of sub-health beam is given.2) The difference between the reliability of sub-health bridge and new bridge is analyzed, consequently, the problem about reasonable limit vehicle load is solved preliminarily in theory.
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Liu, Weiling. "Knowledge map: a creative visual path to library guides and resources." Electronic Library 38, no. 5/6 (November 26, 2020): 943–62. http://dx.doi.org/10.1108/el-03-2020-0055.
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Purpose This paper aims to indicate that library guides seem to be unfamiliar to most students or not easy to find or use. Some improvements have been made by embedding the guides in the learning management system or promoting the guides in formal library instructional classes. Are there other ways to promote or improve the use of library guides? The author proposes an exploratory visual solution to minimize this gap between library users and library guides. Design/methodology/approach Guided by the cognitive load theory, the proposed solution is a knowledge map created with Freeplane. The proposal is illustrated by comparing a sample knowledge map with its content source, a subject guide in LibGuides, via three browsing paths in locating a recommended database for a particular course on the sample subject guide website. Findings The knowledge map can display contents in different ways and provide a simple and visual layout with direct access to the library resources, which may help lessen users’ intrinsic cognitive load, minimize extraneous load or promote germane load. The map can also be beneficial to librarians for preparing teaching materials or guides management. Practical implications The proposed solution can be implemented with Freeplane based on existing library guides or created from scratch. Originality/value The proposed solution addresses a gap in the library field, where the use of knowledge maps for library services is overlooked.
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Thompson, J. Michael T. "Advances in Shell Buckling: Theory and Experiments." International Journal of Bifurcation and Chaos 25, no. 01 (January 2015): 1530001. http://dx.doi.org/10.1142/s0218127415300013.
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In a recent feature article in this journal, coauthored by Gert van der Heijden, I described the static-dynamic analogy and its role in understanding the localized post-buckling of shell-like structures, looking exclusively at integrable systems. We showed the true significance of the Maxwell energy criterion load in predicting the sudden onset of "shock sensitivity" to lateral disturbances. The present paper extends the survey to cover nonintegrable systems, such as thin compressed shells. These exhibit spatial chaos, generating a multiplicity of localized paths (and escape routes) with complex snaking and laddering phenomena. The final theoretical contribution shows how these concepts relate to the response and energy barriers of an axially compressed cylindrical shell. After surveying NASA's current shell-testing programme, a new nondestructive technique is proposed to estimate the "shock sensitivity" of a laboratory specimen that is in a compressed metastable state before buckling. A probe is used to measure the nonlinear load-deflection characteristic under a rigidly applied lateral displacement. Sensing the passive resisting force, it can be plotted in real time against the displacement, displaying an equilibrium path along which the force rises to a maximum and then decreases to zero: having reached the free state of the shell that forms a mountain-pass in the potential energy. The area under this graph gives the energy barrier against lateral shocks. The test is repeated at different levels of the overall compression. If a symmetry-breaking bifurcation is encountered on the path, computer simulations show how this can be suppressed by a controlled secondary probe tuned to deliver zero force on the shell.
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Potočnik, Roki, Jože Flašker, Bostjan Zafošnik, and Srečko Glodež. "The Parametric Study of the Crack Growth in the Lubricated Rolling-Sliding Contact Problems." Key Engineering Materials 348-349 (September 2007): 689–92. http://dx.doi.org/10.4028/www.scientific.net/kem.348-349.689.
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A two-dimensional numerical model is used to describe the crack path in the lubricated rolling-sliding contact problems. The model assumes that the crack is initiated in a pre-existing micro pit, which resulted from the crack growth on the surface of a gear tooth flank. The lubricated rolling-sliding contact problem is modelled using the Hertz theory of contact, the Coulomb's law of friction and hydraulic pressure mechanism with constant pressure which simulates the effect of lubricant trapped into the crack. Different load cases are used to simulate the moving of a contact load. The crack propagation path is evaluated by a maximum tangential stress criterion and modified maximum tangential stress criterion which considers the stress intensity factors KI and KII, the T-stress, the critical distance ahead the crack tip rc, and the stress on the crack surfaces. The computational results show that the consideration of the T-stress has a significant influence on the crack path in the lubricated rolling-sliding contact problems.
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Wei, Li Dui, Shu Lin Duan, Qi Li Wu, Ji Wu, and Wei Guo. "Lubrication Simulation of Main Bearing about a Marine Diesel Engine Based on Multi-Body Dynamics and Elastohydrodynamic." Advanced Materials Research 347-353 (October 2011): 2679–83. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.2679.
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The purpose of this paper is to find a method to study the lubrication character of the main bearings and load condition of the crankshaft about the marine two-stroke diesel engine. Based on the finite element method, multi-body dynamics, elastohydrodynamic and Green-Tripp theory about contact, the simulation of coupling between the elastic crankshaft and engine block is carried out. The load of main bearings, the minimum of oil film thick, orbital path of journal, average of asperity contact pressure are explored. The results indicate that the lubrication is good except No.2 main bearing. Parts of main bearings appear three peaks in a working cycle, which shows that above theory and elastic crankshaft and engine block is obligatory to simulate the lubrication and load condition accurately.
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He, Haoxiang, Honggang Xu, Xiaobing Wang, Xiaofu Zhang, and Shaoyong Fan. "Optimal Sensor Placement for Spatial Structure Based on Importance Coefficient and Randomness." Shock and Vibration 2018 (2018): 1–14. http://dx.doi.org/10.1155/2018/7540129.
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The current methods of optimal sensor placement are majorly presented based on modal analysis theory, lacking the consideration of damage process of the structure. The effect of different minor damage cases acting on the total spatial structure is studied based on vulnerability theory in structural analysis. The concept of generalized equivalent stiffness is introduced and the importance coefficient of component is defined. For numerical simulation, the random characteristics for both structural parameters and loads are considered, and the random samples are established. The damage path of each sample is calculated and all the important members on the damage failure path are listed; therefore the sensor placement scheme is determined according to the statistical data. This method is extended to dynamic analysis. For every dynamic time-history analysis, time-varying responses of the structure are calculated by selecting appropriate calculating interval and considering the randomness of structural parameters and load. The time-varying response is analyzed and the importance coefficient of members is sorted; finally the dynamic sensor placement scheme is determined. The effectiveness of the method in this paper is certified by example.
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Zhang, Pengchao. "Backstepping control based on L1 adaptive theory for large transport aircraft heavy load airdrop." International Journal of Advanced Robotic Systems 15, no. 1 (January 1, 2018): 172988141774948. http://dx.doi.org/10.1177/1729881417749483.
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A study of the L1 adaptive controller is conducted based on the backstepping method for the model of large transport aircraft with drastic changes appearing in heavy load airdrop process. The system is divided into an attitude subsystem and a velocity subsystem. For the attitude subsystem, the backstepping control is used to design the virtual control of path angle and the pitch angle in external loop with the L1 adaptive controller designed in internal loop to estimate the uncertainties and disturbances in the subsystem and to compensate them. In the stability analysis, the uniform boundedness of all signals in the closed-loop system is proven. Simulation results show that the proposed control method preserves the quick dynamic torque response, high efficiency, and robustness in heavy load airdrop; to some extent it can alleviate the control switch lead or lag problem and ensure the safety of the transport aircraft to fulfill the complete airdrop mission.
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Boulbibane, Mostapha, and Ian F. Collins. "Development Of A Pavement Rutting Model Using Shakedown Theory." International Journal on Pavement Engineering & Asphalt Technology 16, no. 1 (May 1, 2015): 55–65. http://dx.doi.org/10.1515/ijpeat-2015-0003.
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Abstract The rutting of flexible pavements during their exploitation is considered to be one of the main problems in UK as well as worldwide. It is a serious mode of distress alongside fatigue in bituminous pavements that may lead to premature failure, as indicated by permanent deformation or rut depth along the wheel load path, and results in early and costly rehabilitation. This kind of pavement distress makes a negative impact to the serviceability characteristics of the flexible pavement, to the residual life of pavement structure and also to the safety and ride quality for traffic. Two design methods have been used to control rutting: one to limit the vertical compressive strain on the top of subgrade and the other to limit rutting to a tolerable amount usually around “12 mm”. Although experimental data and practical experience have been introduced into these design methods through empirical parameters, there is not a simple relationship between the elastic strain and the long-term plastic behaviour of pavement materials. This paper describes a method based on the kinematic shakedown theorem for constructing a mathematical model to predict the long-term behaviour of pavement structures under the action of repeated and cyclic loadings imposed by moving traffic. This method seeks the mechanism from within a class of mechanisms that minimises the shakedown limit load for pavement structures consisting of layers of Mohr-Coulomb materials. The model differs from extant models, in that the cyclic nature of the loading on a pavement is recognised from the outset, and the current method which is based upon foundation analysis, is replaced by a procedure employing shakedown theory that features the capabilities and applications of the developed technique for assessing rutting in flexible pavements. The basic concepts are outlined together with the most recent calculations of the critical design shakedown load. The influence of the design parameters such as, the strength, stiffness and depth of the granular base-course material as well as the consequences of traffic loading (number of equivalent standard axel loads – ESAL’s) are discussed.
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XUE, QIANG, and JOHN L. MEEK. "A REVIEW OF THE INSTABILITY PROBLEM FOR FRAME STRUCTURES." International Journal of Structural Stability and Dynamics 01, no. 02 (June 2001): 181–94. http://dx.doi.org/10.1142/s0219455401000184.
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This paper presents large deflection, post-buckling analysis of plane and spatial elastic frames from a dynamic point of view. A co-rotational formulation combined with small deflection beam theory with the inclusion of the effect of axial force is adopted. A constant arc length method combined with the modified Newton–Raphson iteration method and the extrapolation technique to improve the convergence behaviour are employed to trace the non-linear equilibrium path up to the limit point. The change in the sign of the incremental work done is used to determine the occurrence of a limit point. As the limit state being examined is passed, the previous converged solution is adopted to start the non-linear dynamic analysis based on the average acceleration of the Newmark algorithm with a slow rate of load increment and in order to trace the post-buckling load-deflection path. As a result, the snap through problem is overcome without decreasing the external load. Numerical examples are presented to demonstrate the performance of the method.
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Cai, J. G., Y. X. Xu, J. Feng, and J. Zhang. "Mechanical behaviour of bistable struts." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 226, no. 5 (September 16, 2011): 1321–25. http://dx.doi.org/10.1177/0954406211420618.
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The mechanical behaviour of a bistable structural element, which is based on the snap-through and bifurcation properties of the von Mises truss, has been investigated in this article. By assuming the joint behaviour as ideal hinges and using the large deformation theory based on a linear elastic material, a simple analytical model for the stability of the von Mises truss was formulated. The governing set of non-linear equilibrium equations was obtained by applying the principle of stationary total potential energy. Then, the formulae of the snap-through and bifurcation buckling loads and the equilibrium path were given. In addition to the well-known cases of primary and secondary branches, a third type that the bifurcation buckling point lying on the descending branch of the load versus displacement curve was discussed. In this case, although its upper bifurcation load is lower than its upper snap-through buckling load, the truss experiences a symmetric snap-through mode first, and hence the bifurcation point is not physically relevant. Finally, the assumptions of the classical von Mises truss analysis are discussed.
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Zhan, Yuzhuo, Weimin Lei, Yunchong Guan, and Hao Li. "Research on the Load Distribution Strategy to Meet the QoE Requirements for Conversational Real-Time HD Video Service." Electronics 9, no. 5 (May 11, 2020): 790. http://dx.doi.org/10.3390/electronics9050790.
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A reliable transmission with QoE (Quality of Experience) guarantee is crucial for internet conversational service applications. However, due to the limited network bandwidth bottleneck effect and the drawback of transmission technology, there exists no mature and open QoE technical solution for this service. In this paper, we focused our attention on a load distribution strategy for multipath relay transmission to meet the QoE requirements of conversational real-time HD video services. It consisted of three stages: First, a series of relay nodes was deployed in the backbone network, and a software defined overlay network was constructed to perform the multipath relay transmission for the service. Second, by an analysis of the QoE feature, a bijection was built for each quantitative QoE and its MOS (Mean Opinion Score) score. Finally, considering the influence of the coupling relation between paths on the service quality in multipath relay transmission, fuzzy cooperative game theory was used to design the service load distribution strategy. Many experiments showed that compared with state-of-the-art methods in the single-path transmission scene, the strategy we designed can dynamically adjust the load distribution of each sub-path according to the change in QoS (Quality of Service) information of the transmission path in real time. While meeting the strict real-time constraints of the service, it can effectively avoid the impact of network random congestion on the service QoE.
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Chang, Cheng-Shang. "A new ordering for stochastic majorization: theory and applications." Advances in Applied Probability 24, no. 03 (September 1992): 604–34. http://dx.doi.org/10.1017/s0001867800024435.
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In this paper, we develop a unified approach for stochastic load balancing on various multiserver systems. We expand the four partial orderings defined in Marshall and Olkin, by defining a new ordering based on the set of functions that are symmetric, L-subadditive and convex in each variable. This new partial ordering is shown to be equivalent to the previous four orderings for comparing deterministic vectors but differs for random vectors. Sample-path criteria and a probability enumeration method for the new stochastic ordering are established and the ordering is applied to various fork-join queues, routing and scheduling problems. Our results generalize previous work and can be extended to multivariate stochastic majorization which includes tandem queues and queues with finite buffers.
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Chang, Cheng-Shang. "A new ordering for stochastic majorization: theory and applications." Advances in Applied Probability 24, no. 3 (September 1992): 604–34. http://dx.doi.org/10.2307/1427482.
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In this paper, we develop a unified approach for stochastic load balancing on various multiserver systems. We expand the four partial orderings defined in Marshall and Olkin, by defining a new ordering based on the set of functions that are symmetric, L-subadditive and convex in each variable. This new partial ordering is shown to be equivalent to the previous four orderings for comparing deterministic vectors but differs for random vectors. Sample-path criteria and a probability enumeration method for the new stochastic ordering are established and the ordering is applied to various fork-join queues, routing and scheduling problems. Our results generalize previous work and can be extended to multivariate stochastic majorization which includes tandem queues and queues with finite buffers.
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Zhang, Long, Purong Jia, Bo Wang, and Bin Xu. "Optimization Method of Composite Blade Lay-up Considering Bent-Twist Coupling Effect." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 36, no. 6 (December 2018): 1093–101. http://dx.doi.org/10.1051/jnwpu/20183661093.
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In the design of composite blades, the bent-twist coupling effect can be used to reduce the aeroelastic deformation of the blades by lay-up optimization design to improve the efficiency of blade structure. In this paper, the composite blade was simplified as symmetric unbalanced cantilever laminate, and based on the classical laminated theory(CLT), two analysis parameters are proposed:the stiffness weights and load factors. The influence of the two analysis parameters on the structural deformation of the bent-twist coupling effect is studied by experiments and finite element analysis(FEA). The symmetrical laminated plates containing 0°, 90° and ±45° plies were analyzed and calculated with the feasible region of stiffness weights as the constraint condition and the minimum blade curvature as the objective function, and the optimal path of the stiffness weights relate to the load factors was obtained. A 16-plies symmetric laminated plate was used as an example to verify the optimal path of the stiffness weights. By the inverse calculation of the optimal path of the stiffness weights, the optimal ply sequences can be obtained. The method of this paper may provide some references and basis for the optimal design of the composite blades.
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Sotoudeh, Zahra, and Dewey H. Hodges. "Structural Dynamics Analysis of Rotating Blades Using Fully Intrinsic Equations, Part I: Formulation and Verification of Single-Load-Path Configurations." Journal of the American Helicopter Society 58, no. 3 (July 1, 2013): 1–9. http://dx.doi.org/10.4050/jahs.58.032003.
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As part of an ongoing investigation into potential advantages of so-called fully intrinsic formulations, this paper presents an application of the fully intrinsic equations of motion and kinematics for beams to rotor blades. A fully intrinsic formulation is devoid of displacement and rotation variables. Although the governing equations are geometrically exact, they are free of the attendant singularities and infinite-degree nonlinearities found in other types of formulations. These nonlinear, first-order partial differential equations are suitable for analyzing initially curved and twisted, anisotropic beams and thus are very attractive for analysis of both helicopter and wind turbine blades. This two-part paper is devoted to the structural dynamics modeling of rotor blades with a wide variety of boundary conditions—in particular hingeless and bearingless rotor configurations. In Part I, the theory and the formulation are presented, along with verification of single-load-path configurations. Part II is devoted to the verification of dual-load-path configurations.
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Zhan, Yong, Hai Tao Zhu, and Yu Guang Zhong. "Open Shop Dense Scheduling Algorithm Based on Semi-Matching Theory." Key Engineering Materials 572 (September 2013): 249–52. http://dx.doi.org/10.4028/www.scientific.net/kem.572.249.
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Open shop scheduling problem was studied, and a dense scheduling algorithm based on semi-matching theory was proposed. Using decomposition strategy, the scheduling problem was converted into iterations of resource assignment. Based on this, dense scheduling was constructed by the construction and optimization of primal solution. To improve computational efficiency, the semi-matching model of the resource assignment problem with the optimal function of load balancing was developed. The optimal semi-matching searching algorithm based on augmenting path was proposed. And a dense scheduling construction method with two steps was proposed, as well as initial solution optimization methods and mechanisms to eliminate interference among machines. At last, the validity of the developed scheduling algorithm was illustrated by benchmarks of Taillard.
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Liang, Yixiao, Yinong Li, Ling Zheng, Yinghong Yu, and Yue Ren. "Yaw rate tracking-based path-following control for four-wheel independent driving and four-wheel independent steering autonomous vehicles considering the coordination with dynamics stability." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 235, no. 1 (July 15, 2020): 260–72. http://dx.doi.org/10.1177/0954407020938490.
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The path-following problem for four-wheel independent driving and four-wheel independent steering electric autonomous vehicles is investigated in this paper. Owing to the over-actuated characters of four-wheel independent driving and four-wheel independent steering autonomous vehicles, a novel yaw rate tracking-based path-following controller is proposed. First, according to the kinematic relationships between vehicle and the reference path, the yaw rate generator is designed by linear matrix inequality theory, with the ability to minimize the disturbances caused by vehicle side slip and varying curvature of path. Considering that the path-following objective and dynamics stability are in conflict with each other in some extreme path-following conditions, a coordinating mechanism based on yaw rate prediction is proposed to satisfy the two conflicting objectives. Then, according to the desired yaw rate and longitudinal velocity, a hierarchical structure is introduced for motion control. The upper-level controller calculates the generalized tracking forces while the allocation layer optimally distributes the generalized forces to tires considering tire vertical load and adhesive utilization. Finally, simulation results indicate that the proposed method can achieve excellent path-following performances in different driving conditions, while both path-following objective and dynamics stability can be satisfied.
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Wu, Jiazheng, Hongyun Liu, Yingjun Ruan, Shanshan Wang, Jiamin Yuan, and Huiming Lu. "A Novel Method for Network Design and Optimization of District Energy Systems: Considering Network Topology Planning and Pipe Diameter." Applied Sciences 11, no. 4 (February 18, 2021): 1795. http://dx.doi.org/10.3390/app11041795.
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This paper proposes a new network topology design method that considers all the road nodes, energy stations and load centers to ensure the distribution of pipes along the road. The traditional graph theory and Prim Minimum Spanning Tree (MST) are used to simplify the map and minimize the length of the pipeline. After analyzing the limitations of the traditional network topology model, Point-to-Point (PTP), we present a new model, Energy Station-to-Load Point (ESLP). The model is optimized by minimum cost, not the shortest path. Finally, Pipe Diameter Grading (PDG) is proposed based on ESLP by solving for the pipe diameter that gives the minimum cost under different load demands in the process of optimization. The network design method is effectively applied in a case, and the results show that the path of the optimized plan is 1.88% longer than that of the pre-optimized plan, but the cost is 2.38% lower. The sensitivity analysis shows that the cost of pipeline construction, project life and electricity price all have an impact on the optimization results, and the cost of pipeline construction is the most significant. The difference between the different classifications of pipelines affects whether PDG is effective or not.
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Li, Ming Fang, and Yuan Qi Cai. "A Comparison of Combined and Tubular Cast Steel Joint on Mechanical Properties." Applied Mechanics and Materials 174-177 (May 2012): 1294–98. http://dx.doi.org/10.4028/www.scientific.net/amm.174-177.1294.
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In order to provide scientific basis for design and application of cast steel joint, this paper researches on mechanical properties of tubular-plate combined cast steel joint and tubular cast steel joint, which work in International Expo Center in the most unfavorable load condition. Finite Element Method (FEM) is employed to analysis the mechanical properties of the complex cast steel joint and an optimize solution is given. FEM based on large deformation theory and material nonlinearity obtained ultimate load and failure mode of the joints. The results show that, force transmission path of combined cast steel joint is complex for its cross-section shape of branch changes much; stress concentration is very obvious on the branch. In contrast, the force transmission path of tubular cast steel joint is clear and concise; the phenomenon of stress concentration alleviated effectively, the efficiency of material improved greatly; in the same amount of material, the ultimate bearing capacity of tubular cast steel joint increased by 9.5%. The joint design should follow the principle of simple and practical in premise of mechanical requirements.
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Pedrero, José I., Izaskun I. Vallejo, and Miguel Pleguezuelos. "Calculation of Tooth Bending Strength and Surface Durability of High Transverse Contact Ratio Spur and Helical Gear Drives." Journal of Mechanical Design 129, no. 1 (August 28, 2006): 69–74. http://dx.doi.org/10.1115/1.2403773.
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Calculation methods of spur and helical gear drives with a transverse contact ratio higher than 2, accurate enough for preliminary designs or standardization purposes, are not available in technical literature. If the load is assumed to be uniformly distributed along the line of contact, simple equations given by the linear theory of elasticity and the Hertzian contact model are not in good agreement with experimental results. However, these simple equations may work quite accurately with a more realistic model of load distribution accounting the changing rigidity of the pair of teeth along the path of contact. In this paper a nonuniform model of load distribution along the line of contact, obtained from the minimum elastic potential criterion, has been considered for stress calculation of spur and helical gear drives with transverse contact ratio between 2 and 2.5. The determinant load conditions have been calculated and the nominal contact stress and the nominal tooth-root stress have been computed.
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RODMAN, URBAN, MIRAN SAJE, IGOR PLANINC, and DEJAN ZUPAN. "THE LATERAL BUCKLING OF TIMBER ARCHES." International Journal of Structural Stability and Dynamics 13, no. 08 (October 21, 2013): 1350040. http://dx.doi.org/10.1142/s0219455413500405.
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This paper presents the stability analyses of glulam arches subjected to distributed vertical loading. The present analysis employs a strain-based formulation of a nonlinear geometrically exact three-dimensional beam theory. The influence of the relative height of the arch on the lateral buckling load is studied. The buckling load is determined by bisection method with observing the sign of the determinant of the tangent stiffness matrix. The post-critical load deflection path is traced by a modified arc–length method. Such influences are shown for arches with a constant cross-section or constant volume. After determining the most favorable height of the arch, the influence of the number and position of lateral supports is shown. We also compare the deflections, bending, and radial stresses at the lateral buckling states to the limit values which are recommended by European standards.
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WU, JIAN-JUN, HUI-JUN SUN, ZI-YOU GAO, and SHU-BIN LI. "EFFECTS OF ROUTE GUIDANCE SYSTEMS ON SMALL-WORLD NETWORKS." International Journal of Modern Physics C 18, no. 08 (August 2007): 1243–50. http://dx.doi.org/10.1142/s0129183107011285.
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The route guidance systems (RGS) are efficient in alleviating traffic congestion and reducing transit time of transportation networks. This paper studies the effects of RGS on performance of variably weighted small-world networks. The properties of the average shortest path length, the maximum degree, and the largest betweenness, as important indices for characterizing the network structure in complex networks, are simulated. Results show that there is an optimal guided rate of RGS to minimize the total system cost and the average shortest path length, and proper RGS can reduce the load of the node with maximum degree or largest betweenness. In addition, we found that the load distribution of nodes guided by RGS decay as the power laws which is very important for us to understand and control traffic congestion feasible.
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Song, Qun, and Zhi Lin Yang. "Buckling and Post-Buckling Behavior for Roof Strata in Longwall Mining." Applied Mechanics and Materials 170-173 (May 2012): 751–54. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.751.
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In accordance with the occurrence behavior of roof strata and the fracture characteristics of key stratum in shallow seam longwall mining, this paper studied the post-buckling behaviors of key roof stratum in the process of mining by using initial post-buckling theory, which derived a critical load and a breaking span of the main roof during the first weighting, determined the final subsidence for broken key stratum, and presented an application with the example of Daliuta 1203 face. The results indicate that the rock blocks a in are state of non-equilibrium after main roof breaking, the equilibrium path of main roof is unstable from breaking to final subsidence; thick unconsolidated layers above roof have effect on post-buckling behaviors of key stratum; the stability for bifurcation point equilibrium configuration and post-buckling equilibrium path of roof strata could be revealed and an effective method for determining displacement field of imperfection structure could be provided by using initial post -buckling theory.
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Asmolovskiy, Nikolay, Anton Tkachuk, and Manfred Bischoff. "Numerical approaches to stability analysis of cylindrical composite shells based on load imperfections." Engineering Computations 32, no. 2 (April 20, 2015): 498–518. http://dx.doi.org/10.1108/ec-10-2013-0246.
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Purpose – Current procedures of buckling load estimation for thin-walled structures may provide very conservative estimates. Their refinement offers the potential to use structure and material properties more efficiently. Due to the large variety of design variables, for example laminate layup in composite structures, a prohibitively large number of tests would be required for experimental assessment, and thus reliable numerical techniques are of particular interest. The purpose of this paper is to analyze different methods of numerical buckling load estimation, formulate simulation procedures suitable for commercial software and give recommendations regarding their application. All investigations have been carried out for cylindrical composite shells; however similar approaches are feasible for other structures as well. Design/methodology/approach – The authors develop a concept to apply artificial load imperfections with the aim to estimate as good as possible lower bounds for the buckling loads of shells for which the actual physical imperfections are not known. Single and triple perturbation load approach, global and local dynamic perturbation approach and path following techniques are applied to the analysis of a cylindrical composite shell with known buckling characteristics. Results of simulations are compared with published experimental data. Findings – A single perturbation load approach is reproduced and modified. Buckling behavior for negative values of the perturbation load is examined and a pattern similar to a positive perturbation load is observed. Simulations with three perturbation forces show a decreased (i. e. more critical) value of the buckling load compared to the single perturbation load approach. Global and local dynamic perturbation approaches exhibit a behavior suitable for lower bound estimation for structures with arbitrary geometries. Originality/value – Various load imperfection approaches to buckling load estimation are validated and compared. All investigated methods do not require knowledge of the real geometrical imperfections of the structure. Simulations were performed using a commercial finite element code. Investigations of sensitivity with respect to a single perturbation load are extended to the negative range of the perturbation load amplitude. A specific pattern for a global perturbation approach was developed, and based on it a novel simulation procedure is proposed.
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Jin, Guo Feng, Wei Zhang, Yuan Jia Song, Zheng Wei Yang, and Gan Tian. "Stability Analysis of Rectangular Plate Based on Catastrophe Theory." Applied Mechanics and Materials 148-149 (December 2011): 968–72. http://dx.doi.org/10.4028/www.scientific.net/amm.148-149.968.
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Plates and shells are well used in structures. In order to study the nonlinear stability of plate, the total potential energy expression was deduced after analyzing the geometrical conditions of four ends simply supported rectangular plate on large deflection, the cusp catastrophic model of the rectangular plate was established based on catastrophe theory, and the bifurcation set that makes the system unstable was obtained to analyze the instability conditions of rectangular plate. The instability conditions of rectangular plate were analyzed based on this set, the critical inner stress is at the cusp point, the necessary condition of instability is σ>σcr, but the plate is stable when the movement path of control variables composed by inner stress and landscape load not across the bifurcation curves in the control space. Structures in some projects can be predigested to such a rectangular plate and this cusp catastrophic model can be used for analyzing its instability conditions for taking preventive measures.
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Tong, Xinxing, Wenjie Ge, and Yonghong Zhang. "Topology optimization of compliant mechanisms with curvilinear fiber path laminated composites." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 230, no. 17 (August 9, 2016): 3101–10. http://dx.doi.org/10.1177/0954406215604878.
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An approach for designing compliant mechanisms with curvilinear fiber path laminated composites is presented to obtain the optimum topology structure in this paper. A laminated plate with curvilinear fiber path is built by using the shifted fiber path method. Meanwhile, an equivalent constitutive relationship of the laminated plate has been obtained based on the laminated plate theory. Taking the element relative density as design variable, minimizing the weighted linear combination of the mutual strain energy and the strain energy is considered as an objective function to achieve the desired deformation and enough load-carrying capacity of compliant mechanisms with the volume constraint. The topology optimization problem is solved via the optimality criteria and the sensitivity filtering technology. The numerical examples of designing compliant inverters are investigated to demonstrate the effectiveness of the proposed method. And furthermore, the displacements and the stress levels are also discussed for the compliant inverters with different curvilinear fiber laminated sequences.
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Li, Xiaoling, and Hai Hu. "QoS Routing Algorithm Based on Entropy Granularity in the Network Transmission." Cybernetics and Information Technologies 19, no. 4 (November 1, 2019): 61–72. http://dx.doi.org/10.2478/cait-2019-0036.
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Abstract With the rapid development of computer networks, more hosts are connected to the Internet where they could communicate with each other. The need for network service has exceeded the service capacity of the network, and the Quality of Service (QoS) is gradually declining. Based on existing Shortest Path First (SPF) algorithm, this paper proposes a new QoS required transmission path approach by considering the overhead balance of network resources. This paper uses the entropy granularity as the main line in the application of routing protocols. Firstly, it researches the optimization of routing algorithms for network load balancing resources, routing algorithms based on link traffic distributing weights, link weight optimization based on adaptive genetic algorithm and computational intelligence based on entropy granularity theory. This research proposes a method to apply entropy granularity to Open Shortest Path First (OSPF) routing, including the implementation of the method. After that, a case study is presented by using some examples.
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Gao, Meng Qi, Ping Ying Wang, and He Ping Ding. "Analysis on the Fatigue Life of Asphalt Pavement under Traffic Flow Loads." Applied Mechanics and Materials 361-363 (August 2013): 1727–34. http://dx.doi.org/10.4028/www.scientific.net/amm.361-363.1727.
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To study the fatigue life of asphalt pavement under traffic loads, a 3-D finite element analysis (FEA) Visio-elastic road model was established on the layered theory with ANSYS software. The fatigue damage was calculated with the maximum horizontal tensile strain of asphalt layer bottom based on the fatigue fracture mechanics, when single axis went across. Then the fatigue life was obtained after the fatigue damage occurred in some degree by the Miners linear cumulative damage rule. The results show that it taken 3.4 years when the damage area reached 10% of wheel path area, and 4.5years when reached 45%; while the calculated result was 5.5 years by axial-load conversion method. The analysis shows that the fatigue life of asphalt pavement calculated by fatigue fracture mechanics rule has more significance in practice.
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DV, Shwetha, and Lakshman Rao S. Paragond. "Comparison of the different controlling techniques for buck converter in LED application." International Journal of Power Electronics and Drive Systems (IJPEDS) 10, no. 1 (March 1, 2019): 256. http://dx.doi.org/10.11591/ijpeds.v10.i1.pp256-264.
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<p>This paper recounts the design and construction of various controlling techniques for buck converter. If the designed controller for any converter is not proper which leads to high overshoot and steady state error, and its dynamic response varies with changes in load, especially at high load current conditions. The lead-lag controller for the converter is desgined using classical control theory ,Bode Plot technique is used to examine the stability of the system.By using deravetive part of the PID controller on output signal instead of voltage error signal,this combination of control technique reduces the overshoot and settling time,and how the transient response will be affected if deravetive controller is in the forward path.</p>
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Alshannaq, Ammar A., Lawrence C. Bank, David W. Scott, and Russell Gentry. "A Decommissioned Wind Blade as a Second-Life Construction Material for a Transmission Pole." Construction Materials 1, no. 2 (July 7, 2021): 95–104. http://dx.doi.org/10.3390/constrmater1020007.
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This paper demonstrates the concept of adaptive repurposing of a portion of a decommissioned Clipper C96 wind turbine blade as a pole in a power transmission line application. The current research program is aimed at creating a path towards sustainable repurposing of wind turbine blades after they are removed from service. The present work includes modelling and analysis of expected load cases as prescribed in ASCE 74 and NESC using simplified boundary conditions for tangent pole applications. Load cases involving extreme wind, concurrent ice and wind, extreme ice, differential ice, broken conductor, and broken shield have been analyzed and governing load cases for bending, shear, and torsion have been examined. Relative stiffnesses of different parts forming the wind blade’s cross section (i.e., shell, web, and spar cap) are determined. The corresponding stresses associated with each part under the governing loads are compared to allowable strength values which are determined from composite laminate theory and modelling of the known laminate structure of the E-Glass FRP material. Stresses and deflections obtained are compared with governing reliability-based design criteria and code requirements. The results of the structural analysis indicate that the wind blade can resist the expected loads with reasonable safety factors and that the expected deflections are within permissible limits. Recommendations are provided for detailing and modification of the wind blade for a power pole application in which crossarm and davit connections are highlighted, and foundation details are emphasized.
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Galaburdin, A. V. "The problem of infinite plate loaded with normal force following a complex trajectory*." Vestnik of Don State Technical University 19, no. 3 (October 4, 2019): 208–13. http://dx.doi.org/10.23947/1992-5980-2019-19-3-208-213.
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Introduction. A method for solving the problem of an infinite plate on an elastic foundation is proposed. The plate is affected by a periodic load in the form of a force following an arbitrary closed path. The work objective is to develop a numerical method for solving problems of the elasticity theory for bodies under a moving load. Materials andMethods. Given the periodicity of the load under consideration, it is decomposed in a Fourier series in a time interval whose length is equal to the load period. The solution to the original problem is constructed by superposition of the solutions to the problems corresponding to the load specified by the terms of the Fourier series described above. The final solution to the problem is presented as a segment of a series. In this case, each term corresponds to the solution of the problem of the impact on an infinite plate of a load distributed along a closed curve (the trajectory of the force motion). To find these solutions, the fundamental solution to the equation of vibration of an infinite plate lying on an elastic base is used.Research Results. A new method is proposed for solving problems on the elasticity theory for bodies with a load following a closed path of arbitrary shape. The problem of an infinite plane along which a concentrated force moves at a constant speed is solved. It is determined that the trajectory of motion is a smooth closed curve consisting of circular arcs. The behavior of displacements and stresses near a moving force is considered. The energy propagation of the elastic waves is studied. For this purpose, the coordinates of the Umov – Poynting vector are calculated. The effect of the force motion speed on the length of the Umov – Poynting vector is investigated.Discussion and Conclusions. The method is applicable when considering more complex objects (plates of complex shape, layered plates, viscoelastic plates). Its advantage is profitability since the known problem solutions are used to build the solution. The final decision is expressed in a convenient form – as the sum of curvilinear integrals. The results obtained can be used in the road design process. Studying the energy propagation of elastic waves from moving vehicles will enable to evaluate the impact of these waves on buildings near the road. The wear of the pavement is estimated considering data on the behavior of displacements and stresses
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Wang, Jing-min, Yan Liu, Yi-fei Yang, Wei Cai, Dong-xuan Wang, and Zhao-wei Jia. "The Location of Electric Vehicle Charging Stations based on FRLM with Robust Optimization." International Journal of Pattern Recognition and Artificial Intelligence 33, no. 08 (June 25, 2019): 1959027. http://dx.doi.org/10.1142/s0218001419590274.
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It is very important for the application of artificial intelligence to accurately and quickly help the electric vehicles to find matching charging facilities. The site selection for electric vehicle charging station (EVCS) is a new field of artificial intelligence application, using artificial intelligence to analyze the current complex urban electric vehicle driving path, and then determining the location of charging stations. This paper proposes a novel hybrid model to decide the location of EVCS. First of all, this paper carries out the flow-refueling location model (FRLM) based on path requirement to determine the site selection of EVCS. Secondly, robust optimization algorithm is used to resolve the location model considering the uncertainty of charging demand. Then, queuing theory, which takes the charging load as a constraint in the location model, is integrated into the model. Last, but not the least, a case is conducted to verify the validity of the proposed model when dealing with location problem. As a result of the above analysis, it is effective to apply robust optimization algorithm and to determine the location of EVCSs effectively when charging demand generated on the path is uncertain. At the same time, queuing theory can help to determine the optimal number of EVCSs effectively, and reduce the cost of building EVCSs.
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Wang, Zheng, Kui Wang, Lu Wang, and Zi Hao Zhao. "Study on Group Behavior of Short Crack for Low Cycle at High Temperature Based on Fractal Theory." Advanced Materials Research 228-229 (April 2011): 1143–49. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.1143.
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The propagation of fatigue short crack is a fractal curve, the irregular path can be described by fractal dimension. The fractal dimension of the crack implicit in many of the physical factors, such as microstructure of material, load conditions and so on. In this paper, the short crack for low cycle at high temperature is studied. The material 20# steel in the various stress state is experimentally studied, the initiation, propagation and coalescence influence of short crack are observed. By analyzing experiment results, characters of crack fractal dimensions evolving with the cycle process are as follows, the behavior of short fatigue cracks satisfies fractal feature, with the development of the fatigue process, the fractal dimension is increased.
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Wang, Yu Sheng, Ming Ming Wang, and Ming Yan. "Research on Contact Deformation and Influencing Factor of Ball Screw." Advanced Materials Research 430-432 (January 2012): 755–59. http://dx.doi.org/10.4028/www.scientific.net/amr.430-432.755.
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It was calculated contact deformation of ball screw respectively by hertz theory and finite element method, and analyzed the influencing factors. It is found that as the gradually increasing of ball screw load, axial deformation is also increasing gradually,and its deformation gradually smooths. As the increasing of lead angle, deformation of ball screw is gradually decreasing. As the increasing of contact angle, deformation of ball screw is gradually decreasing. Finite element calculated results are in good agreement with the theoretical results,and the error is gradually increasing with the increase of the nut load.The reason is that turning of ball is not fixed in the roller path,and along with the increase of the load, the contact point position is constantly changing among ball,leading screaw and nut.
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Han, Cheng Shuang, Hong Mei Zhang, and Zai Ling Cheng. "Modeling for Initial Post-Buckling Analysis of Laminated Plates and Shells by FEM." Applied Mechanics and Materials 166-169 (May 2012): 520–25. http://dx.doi.org/10.4028/www.scientific.net/amm.166-169.520.
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Nonlinear analysis of plate and shell structures can explain the phenomenon which cannot been explained by classical stability theory, and can obtain better validation of experimental results. Stability problems are essentially nonlinear and their nonlinear finite element solutions ultimately result in solving nonlinear algebraic equations and nonlinear eigenvalue problems. The solutions can define the shape of basic path and determine critical load by using the incremental method, The perturbation methods are used near the critical point, and the basic formulas are given for initial post-buckling analysis by FEM.
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Yang, Xue, Li Yu, and Xiao-Shun Zhao. "Optimization of the reefed parachute using genetic algorithm." Engineering Computations 34, no. 6 (August 7, 2017): 1923–38. http://dx.doi.org/10.1108/ec-05-2016-0163.
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Purpose The purpose of this paper is to find optimal reef parameters to minimize the maximum instantaneous opening load for a reefed parachute with geometry and environmental parameters given in the model. Design/methodology/approach The dynamic model Drop Test Vehicle Simulation (DTVSim) is used to model the inflation and descent of the reefed parachute system. It is solved by the fourth-order Runge–Kutta method, and the opening load values are thereby obtained. A parallel genetic algorithm (GA) code is developed to optimize the reefed parachute. A penalty scheme is used to have the maximum dynamic pressure restricted within a certain range. Findings The simulation results from DTVSim fit well with experimental data from drop tests, showing that the simulator has high accuracy. The one-stage and two-stage reefed parachute systems are optimized by GA and their maximum opening loads are decreased by 43 and 25 per cent, respectively. With the optimal reef parameters, two of the peaks in the opening load curve are almost equal. The velocity, loiter time and flight path angle of the parachute system all change, but these changes have no negative effect on the parachute’s operational performance. Originality/value An optimization method for reefed parachute design is proposed for the first time. This methodology can be used in the preliminary design phase for a reefed parachute system and significantly improve design efficiency.
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Kolakowski, Zbigniew, and Andrzej Teter. "Eigenproblem Versus the Load-Carrying Capacity of Hybrid Thin-Walled Columns with Open Cross-Sections in the Elastic Range." Materials 14, no. 13 (June 22, 2021): 3468. http://dx.doi.org/10.3390/ma14133468.
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The phenomena that occur during compression of hybrid thin-walled columns with open cross-sections in the elastic range are discussed. Nonlinear buckling problems were solved within Koiter’s approximation theory. A multimodal approach was assumed to investigate an effect of symmetrical and anti-symmetrical buckling modes on the ultimate load-carrying capacity. Detailed simulations were carried out for freely supported columns with a C-section and a top-hat type section of medium lengths. The columns under analysis were made of two layers of isotropic materials characterized by various mechanical properties. The results attained were verified with the finite element method (FEM). The boundary conditions applied in the FEM allowed us to confirm the eigensolutions obtained within Koiter’s theory with very high accuracy. Nonlinear solutions comply within these two approaches for low and medium overloads. To trace the correctness of the solutions, the Riks algorithm, which allows for investigating unsteady paths, was used in the FEM. The results for the ultimate load-carrying capacity obtained within the FEM are higher than those attained with Koiter’s approximation method, but the leap takes place on the identical equilibrium path as the one determined from Koiter’s theory.
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Zhao, Wei Tao, and Da Qian Zhang. "Discussion of Reliability Analysis for Aircraft Wing Box Structural System." Advanced Materials Research 118-120 (June 2010): 236–40. http://dx.doi.org/10.4028/www.scientific.net/amr.118-120.236.
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It is very complex problem that the reliability of aircraft wing box structural system with many random variables (such as area, thickness, material modulus, load etc.) is analyzed. In the paper, the reliability analysis method of aircraft wing box structural system is proposed based on the theory of structural reliability and stochastic finite element. The explicit expression of safe margin and the sensitivity of safe margin to each random variable are given, which improves the accuracy and efficiency of reliability calculation. The relationship of the level of failure path with structural system failure probability is discussion. The failure probability of element is calculated by using first order second moment method, and the main failure path of structural system is identified by using the advanced branch and bound method, and the failure probability of structural system is evaluated by using probabilistic network evaluation technique method. Numerical examples show that the method is of efficient and accurate, and the 3 or 4 level of failure path is acceptable for wing box structural system considering efficiency and accuracy.
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Guo, Jin, Shengbing Zhang, Bo Zheng, Hengyang Zhang, and Weilun Liu. "Study on Multi-Priority and Multi-Path QoS Routing Protocol for Airborne Heterogeneous Networks." Xibei Gongye Daxue Xuebao/Journal of Northwestern Polytechnical University 37, no. 4 (August 2019): 851–56. http://dx.doi.org/10.1051/jnwpu/20193740851.
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In order to guarantee the QoS requirements of multiple services in airborne all-domain heterogeneous and flexible networks, we propose a novel multi-priority and multi-path based QoS routing (MP2R) protocol in this paper. In the protocol, in terms of the route effectiveness and reliability, the route cost penalty function is constructed based on the multi-priority M/M/1 queueingqueuing system with the preemptive-resume policy. The minimum value of the function is derived through the optimization theory, and the optimum routing solution is acquired. The simulation results show that the MP2R protocol not only has the capabilities of differentiation services for different kinds of traffic and QoS provision, but also can utilize the network resource rationally, avoid congestion, achieve the load balancing, and meet the requirements of airborne all-domain heterogeneous and flexible networks effectively.
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Cho, Hye-Kyung, Bum-Hee Lee, and Myoung-Sam Ko. "Path constrained time-optimal motion of a cooperative two robot system." Robotica 13, no. 4 (July 1995): 363–74. http://dx.doi.org/10.1017/s0263574700018798.
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SummaryThis paper presents a systematic approach to the time-optimal motion planning of a cooperative two robot system along a prescribed path. First, the minimum-time motion planning problem is formulated in a concise form by parameterizing the dynamics of the robot system through a single variable describing the path. The constraints imposed on the input actuator torques and the exerted forces on the object are then converted into those on that variable, which result in the so-called admissible region in the phase plane of the variable. Considering the load distribution problem that is also involved in the motion, we present a systematic method to construct the admissible region by employing the orthogonal projection technique and the theory of multiple objective optimization. Especially, the effects of viscous damping and state-dependent actuator bounds are incorporated into the problem formulation so that the case where the admissible region is not simply connected can be investigated in detail. The resultant time-optimal solution specifies not only the velocity profile, but also the force assigned to each robot at each instant. Physical interpretation on the characteristics of the optimal actuator torques is also included with computer simulation results.
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Wang, Fei, Yu’e Ma, Yanning Guo, and Wei Huang. "Numerical studies on mixed-mode crack propagation behavior for functionally graded material based on peridynamic theory." International Journal of Computational Materials Science and Engineering 07, no. 04 (December 2018): 1850027. http://dx.doi.org/10.1142/s2047684118500276.
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Peridynamics (PD) is a new nonlocal theory that unifies the mechanics of discrete particles, continuum, and continuum with discontinuities, and it has inherent advantages in calculating the mixed-mode crack propagating. Functionally graded materials (FGMs) are the advanced composite materials, fracture behavior of which is complicated to be simulated by the traditional continuum mechanics. Hence, a PD model for FGMs is given to investigate the mixed-mode fracture behavior under quasi-static loading. Basic PD equations, damage model, and PD [Formula: see text]-integral for FGMs are discussed. A FORTRAN program of PD algorithm is coded to calculate the [Formula: see text]-integral and crack propagation of FGMs. The [Formula: see text]-integral and the crack paths of the PD model are verified by comparing with the published numerical and experimental results. Effects of the material gradient, the material gradient direction, and the stress load magnitude on the fracture behavior are investigated. It is shown that the PD [Formula: see text]-integral and the crack path are strongly affected by the material gradient and the gradient direction under the same stress load. When the gradient of FGMs is linear, the material gradient direction decides whether the mixed-mode crack kinks or not and the magnitude of stress determines the kinking angle.
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Yu, Qun, Ya Di Wang, Ji Hong Han, Hong Shan Kong, and Yu Chen Zhang. "The Analysis of the Two-Wire Transmission Line in a Cavity with Apertures Illuminated by a Plane Wave Based on Electromagnetic Topology." Applied Mechanics and Materials 110-116 (October 2011): 4133–39. http://dx.doi.org/10.4028/www.scientific.net/amm.110-116.4133.
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By using electromagnetic topology (EMT) method, this paper discusses the issue of the electromagnetic field penetration through an aperture to a cavity and coupling to a two-wire transmission line in the cavity. By representing the electromagnetic field propagation path as “tube”, and combining with transmission line theory, this paper creates the Baum-Liu-Tesche (BLT) equation of radiation coupling. Then, by employing the BLT equation, the semi-analytic solutions of the load response of the two-wire transmission line in the cavity are obtained. Numerical examples are constructed to demonstrate the validity of this technique.