High Isolation and Low Correlation Small Size Multi-Antenna for MIMO Mobile Terminals

A new method of forming a four-port multi-antenna by a two-unit patch antenna array is proposed to design a high isolation low correlation stroll size multi-antenna. Dual polarization is real-ized by the method of feeding in two ports. Defec-ted Ground Structure （DGS） is used to eliminate the coupling between the two antenna units. The test results show that the isolation between two ports reaches around 20dB, and that the antenna correlation coefficients is less than 0. 5, which meets the requirements of future mobile communi-cation systems and provides a solution to multi-antenna of MIMO terminals.

An approach to noble-gas isotopic compositions in natural gases and gas-source tracing in the Ordos Basin,China

Isotopic compositions of noble gases, i.e. He Ar Kr and Xe, are measured in natural gases from the Zhongbu gasfield in the Ordos Basin. And heavy noble-gas isotopes (Kr, Xe) are here first used in geochemically studying natural gases and gas-source correlation. Isotopic compositions of heavy noble gases in natural gases, especially Xe, show two-source mixing in the Zhongbu gasfield. Gas sources are somewhat different in the northeast and the southwest of the gasfield. Generally, the gas source of the Lower Paleozoic makes a greater contribution in the southwest than in the northeast in the field. Two kinds of gases can be differentiated from isotopic compositions of heavy noble gases and from their relation with the Ar isotopic composition. Therefore, the comprehensive study on isotopic compositions of light and heavy noble gases can supply more useful information on gas-source correlation and tracing.

Uncertainty analysis of correlated non-normal geotechnical parameters using Gaussian copula

Determining the joint probability distribution of correlated non-normal geotechnical parameters based on incomplete statistical data is a challenging problem.This paper proposes a Gaussian copula-based method for modelling the joint probability distribution of bivariate uncertain data.First,the concepts of Pearson and Kendall correlation coefficients are presented,and the copula theory is briefly introduced.Thereafter,a Pearson method and a Kendall method are developed to determine the copula parameter underlying Gaussian copula.Second,these two methods are compared in computational efficiency,applicability,and capability of fitting data.Finally,four load-test datasets of load-displacement curves of piles are used to illustrate the proposed method.The results indicate that the proposed Gaussian copula-based method can not only characterize the correlation between geotechnical parameters,but also construct the joint probability distribution function of correlated non-normal geotechnical parameters in a more general way.It can serve as a general tool to construct the joint probability distribution of correlated geotechnical parameters based on incomplete data.The Gaussian copula using the Kendall method is superior to that using the Pearson method,which should be recommended for modelling and simulating the joint probability distribution of correlated geotechnical parameters.There exists a strong negative correlation between the two parameters underlying load-displacement curves.Neglecting such correlation will not capture the scatter in the measured load-displacement curves.These results substantially extend the application of the copula theory to multivariate simulation in geotechnical engineering.

Simple estimation of electron correlation energy for multi-atomic strong ionic compounds KX and (KX)_2 (X=OH, NC)

On the basis of the calculations and analyses of the intrapair and interpair correlation energy of KX (X = OH, NC) molecules and the results of the transferability of both the innermost intrapair correlation energy and the inner core effect of K and X in KX molecules, we defined and calculated the Kδ- and Xδ-correlation contributions to the total correlation energy of KX molecules. With the comparison of the pair correlation energy of K+, X- and KX systems, we present a simple estimation method to estimate the electron correlation energy of strong ionic compound by summarizing the correlation energy of its constituent ion and ionic group. By using this simple method, the reasonable estimation results of the correlation energy of (KOH)2 and (KNC)2 have been obtained at mp2/6-311++G(d) level with Gaussian98 program, and the deviations are very small. Applying the scheme of 'Separate Large System into Smaller Ones' to the calculation of electron correlation energy of large ionic compounds, it can not only save lot of computation work but also reach the chemical accuracy.

Stability analysis and a priori error estimate of explicit Runge-Kutta discontinuous Galerkin methods for correlated random walk with density-dependent turning rates

In this paper,we analyze the explicit Runge-Kutta discontinuous Galerkin(RKDG)methods for the semilinear hyperbolic system of a correlated random walk model describing movement of animals and cells in biology.The RKDG methods use a third order explicit total-variation-diminishing Runge-Kutta(TVDRK3)time discretization and upwinding numerical fluxes.By using the energy method,under a standard CourantFriedrichs-Lewy(CFL)condition,we obtain L2stability for general solutions and a priori error estimates when the solutions are smooth enough.The theoretical results are proved for piecewise polynomials with any degree k 1.Finally,since the solutions to this system are non-negative,we discuss a positivity-preserving limiter to preserve positivity without compromising accuracy.Numerical results are provided to demonstrate these RKDG methods.