Current Issue : January - March Volume : 2017 Issue Number : 1 Articles : 5 Articles
A novel dynamic co-simulation methodology of overall wind turbine systems is presented.\nThis methodology combines aerodynamics, mechanism dynamics, control system dynamics, and\nsubsystems dynamics. Aerodynamics and turbine properties were modeled in FAST (Fatigue,\nAerodynamic, Structures, and Turbulence), and ADAMS (Automatic Dynamic Analysis of Mechanical\nSystems) performed the mechanism dynamics; control system dynamics and subsystem dynamics\nsuch as generator, pitch control system, and yaw control system were modeled and built in\nMATLAB/SIMULINK. Thus, this comprehensive integration of methodology expands both the\nflexibility and controllability of wind turbines. The dynamic variations of blades, rotor dynamic\nresponse, and tower vibration can be performed under different inputs of wind profile, and the\ncontrol strategies can be verified in the different closed loop simulation. Besides, the dynamic\nsimulation results are compared with the measuring results of SCADA (Supervisory Control and\nData Acquisition) of a 2MW wind turbine for ensuring the novel dynamic co-simulation methodology....
The contact problem of an Euler-Bernoulli nanobeam of finite length bonded to a homogeneous elastic half plane is studied in the\npresent work. Both the beam and the half plane are assumed to display a linear elastic behaviour under infinitesimal strains. The\nanalysis is performed under plane strain condition.Owing to the bending stiffness of the beam, shear and peeling stresses arise at the\ninterface between the beam and the substrate within the contact region.The investigation allows evaluating the role played by the\nPoisson ratio of the half plane (and, in turn, its compressibility) on the beam-substrate mechanical interaction. Different symmetric\nand skew-symmetric loading conditions for the beam are considered, with particular emphasis to concentrated transversal and\nhorizontal forces and couples acting at its edges. It is found that the Poisson ratio of the half plane affects the behaviour of the\ninterfacial stress field, particularly at the beam edges, where the shear and peel stresses are singular....
Undergraduate robotics students often find it difficult to design and validate control algorithms for teams of mobile robots. This is\nmainly due to two reasons. First, very rarely, educational laboratories are equipped with large teams of robots, which are usually\nexpensive, bulky, and difficult to manage and maintain. Second, robotics simulators often require students to spend much time to\nlearn their use and functionalities. For this purpose, a simulator of multi agent mobile robots named MARS has been developed\nwithin the Matlab environment, with the aim of helping students to simulate a wide variety of control algorithms in an easy way\nand without spending time for understanding a new language. Through this facility, the user is able to simulate multi robot teams\nperforming different tasks, from cooperative to competitive ones, by using both centralized and distributed controllers. Virtual\nsensors are provided to simulate real devices. A graphical user interface allows students to monitor the robots behaviour through\nan online animation....
Dynamic contact analysis on the level of surface asperities is a powerful means to study the wear behavior of surface and\nthe physical contact properties of interface. This article established an analytical model of asperity contacts between\nnominal rough planes during sliding process based on the statistical contact analysis of rough surfaces. The analytical\nexpression describes the mathematical relationship between the total number of asperity contacts and its main influencing\nfactors including the nominal contact area, sliding distance, the spacing between two contact planes, and surface\ntopographical parameters. A simulation model of dynamic contact of asperities on rough planes was established to rapidly\ncalculate the number of asperity contacts during the sliding process. The comparison between the calculation results\nand simulation results of the number of asperity contacts obtained through multifactor and multilevel analysis verified\nthe rationality of the analytical model....
Hydraulic hammer is commonly used hydraulic equipment in engineering work. The\ncharacteristics, high acceleration, high frequency and inertial working pressure,\nmake it greatly different from the working conditions of conventional hydraulic\nequipment, while hydraulic hammer for sleeve type is also not the same as other hydraulic\nhammers in structure, efficiency and working performance. Based on the\nprinciple of hydraulic hammer for sleeve type, the mathematical model of hydraulic\nhammer for sleeve type was set with various conditions in the reciprocating movement\nof piston. In addition, more detailed sketch model can be easily built with the\nmathematical model in multi-domain system analysis software, AMESim. The simulation\nsystem of breaker built based on the principle of power bond graph structures\nin AMESim system is considered comprehensively to achieve its functions and characteristics,\nwhich can quickly realize the calculation of main simulation parameters\nfor impactor. The calculated parameters can be proved to be biased with the test\nprototype. So these parameters must be optimized by Design Exploration to find the\nappropriate parameters....
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