Current Issue : January - March Volume : 2018 Issue Number : 1 Articles : 5 Articles
A new sparse Gauss-Hermite cubature rule is designed to avoid dimension explosion caused by the traditional full tensor-product\nbased Gauss-Hermite cubature rule. Although Smolyak�s quadrature rule can successfully generate sparse cubature points for high\ndimensional integral, it has a potential drawback that some cubature points generated by Smolyak�s rule have negative weights,\nwhich may result in instability for the computation. A relative-weight-ratio criterion based sparse Gauss-Hermite rule is presented\nin this paper, in which cubature points are kept symmetric in the input space and corresponding weights are guaranteed to be\npositive.The generation of the newsparse cubature points set is simple and meaningful for practice.The difference between our new\nsparseGauss-Hermite cubature rule and other cubature rules is analysed. Simulation results showthat, comparedwithKalman filter\nwith those types of full tensor-product based Gauss-Hermite rules, our newsparse Gauss-Hermite cubature rule basedKalman filter\ncan lead to a substantially reduced number of cubature points, more stable computation capability, and maintaining the accuracy\nof integration at the same time....
Frequency regulation is essential for the stability of a power grid with high load fluctuation\nand integration of new energies. Constrained by the large ramping, a generator alone is not capable\nof conducting load frequency controls effectively and economically. In this paper, an energy storage\nsystem (ESS) is introduced to coordinate with generators in automatic generation control (AGC),\nwhere ESS and the generator respectively deal with high-frequency load fluctuation and low-portion.\nWe develop a system configuration framework for such a hybrid system, including the operation\nstrategy and capacity optimization. Due to the complexity of the hybrid system, the operation process\nis captured by a simulation model which considers practical constraints as well as remaining energy\nmanagement of ESS. Taking advantage of the gradient-based approximation algorithm, we are then\nable to optimize the capacity of a hybrid system. According to the numerical experiments with real\nhistorical AGC data, the hybrid system is shown to perform well in cost reduction and to achieve the\nregulation tasks....
The melting of paraffin in thermal storage tube-and-shell and combine-and-shell models was conducted with the numerical\nresearch aim of decreasing the charge time through changing the shape of the tube into combining form. The results discussed\nare temperature contour, liquid-solid interface contour, temperature distribution, liquid fraction, and the average Nusselt number.\nThe results show that the charge time in the tube-and-shell model is 2000 s, while the combine-and-shell model is 1200 s, meaning\nan overall decrease in charge time in the combine-and-shell model by 40% when compared to that of the tube-and-shell model....
Statement of the Problem. The article describes the problem of combined thermal-seepage regime for earth dams and those\noperated in the permafrost conditions. This problem can be solved using the finite elements method based on the local variational\nformulation. Results. A thermal-seepage regime numericalmodel has been developed for the ââ?¬Å?dam-foundationââ?¬Â system in terms of\nthe tailings dam.Theeffect of heat-and-mass transfer and liquid phase transition in soil interstices on the damstate is estimated.The\nstudy with subsequent consideration of these factors has been undertaken. Conclusions.The results of studying the temperaturefiltration\nconditions of the structure based on the factors of heat-and-mass transfer and liquid phase transition have shown that the\ncalculation results comply with the field data. Ignoring these factors or one of them distorts the real situation of the dam thermalseepage\nconditions....
The paper analyzed flow characteristics in vortex diode with double tangential\ntube by numerical simulation. Compared to traditional vortex diode with one\ntangential tube, the structure of double tangential tube can reduce the forward\nresistance and improve overall performance. The symmetrical design adopted\nin vortex diode with double tangential tube; the internal flow field in chamber\nshowed symmetrical distribution in the reverse flow, which can improve the\nflow stability and accelerate the convergence speed in simulation....
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