Current Issue : January - March Volume : 2015 Issue Number : 1 Articles : 5 Articles
This paper investigates static output feedback guaranteed cost control for a class of nonlinear discrete-time systems where the\ndelay in state vector is inconsistent with the delay in nonlinear perturbations. Based on the output measurement, the controller is\ndesigned to ensure the robust exponentially stability of the closed-loop system and guarantee the performance of system to achieve\nan adequate level. By using the Lyapunov-Krasovskii functional method, some sufficient conditions for the existence of robust\noutput feedback guaranteed cost controller are established in terms of linearmatrix inequality. A numerical example is provided to\nshow the effectiveness of the results obtained...
Thermal comfort providing is one of the biggest uses of energy in building. For giving better human comfort, the suitable operation\nconditions of air-conditioner are the most important. The quick and right approach is necessary. In this paper, a small office is\nstudied to improve office staff staying for a long period of time and achieve the thermal comfort environment for reducing energy\nconsumption.Commercial software, Solid works, is utilized form odeling the facilities and the Flow Simulation module for analyzing\nthe air properties of the indoor space. Four types of air-conditioner operation are applied to set the simulated conditions, including\nexterior temperature, outlet temperature and wind speed of air-conditioner, and location of air-conditioner. Predicted mean vote\n(PMV) and predicted percent dissatisfied (PPD) at specific office areas are further acquired through dynamic an thropometry. For\nseeking the optimal control factors, both of the full factorial method and Taguchi method are utilized to obtain the PMVof specified\nlocation. The analyzed result shows the evaluation speed of indoor thermal comfort by Taguchi method is faster than the full factorial\nmethod. It is concluded that software simulation with Taguchi method shows the successful implementation and higher\nefficiency for thermal comfort assessment....
A numerical method for evaluating the vertical vibration isolation effect of pile rows embedded in a viscoelastic half space subjected\nto a moving load is developed in this paper on the basis of the Cole-Cole model and Muki�s method. Based on the proposed\nmethod, the influence of various parameters on the vibration isolation effect of pile rows embedded in the viscoelastic half space is\ninvestigated numerically....
Cavitation is a negative factor of hydraulic machinery because of its undesirable effects on the operation stability and safety.\nFor reversible pump-turbines, the improvement of cavitation inception performance in pump mode is very important due to\nthe strict requirements. The geometry of blade leading edge is crucial for the local flow separation which affects the scale and\nposition of pressure drop. Hence, the optimization of leading edge shape is helpful for the improvement of cavitation inception\nperformance. Based on the genetic algorithm, optimization under multiple flow rate conditions was conducted by modifying the\nleading edge ellipse ratio and blade thickness on the front 20% meanline. By using CFD simulation, optimization was completed\nwith obvious improvements on the cavitation inception performance. CFD results show that the pressure drop location had\nmoved downstream with the increasement of the minimum pressure coefficient. Experimental verifications also got an obvious\nenhancement of cavitation inception performance. The stability and safety was improved by moving the cavitation inception curve\nout of the operating range. This optimization is proved applicable and effective for the engineering applications of reversible pumpturbines....
The transport message security provided by vehicles in VANETs is quite important; vehicle message should be real-time and it will\nbe not complicated to validate message calculation. The method proposed in the essay is mainly to validate the identity by means\nof Bilinear Diffie-Hellman method, and make vehicles validate the authenticity of RSU and TA�s identity and the effectiveness of\nkey. RSU and TA only need to validate vehicle identity, without helping vehicles produce any key.When vehicle identity validation\nis completed, vehicles will produce public value and transmit it to other RSU and vehicles, while other vehicles could validate the\nidentity through the message from the sender and public value from RSU. The advantages of the method proposed in this essay are\nlisted as follows. (1) Vehicles, RSU, and TA can validate mutual identities and the effectiveness of keys. (2) Vehicles can produce\npublic value functions automatically, thus reducing key control risks. (3) Vehicles do not need to show certificates to validate their\nidentities, preventing the certificates fromattacking because of long-termexposure. (4)Vehicles adopt a pseudonymI Dchallenge to\nvalidate their own identities during the process of handoff. (5) Vehicle messages can be validated using the Bilinear Diffie-Hellman\n(BDH) method without waiting for the RSU to validate messages, thus improving the instantaneity of messaging. The method\nproposed in the essay can satisfy source authentication, message integrity, nonrepudiation, privacy, and conditional untraceability\nrequirements....
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