Abstract:Hierarchical identification is an important branch of system identification.The hierarchical identification principle is developed on the bisis of the "decomposition-coordination principle" in the hierarchical control for a large-scale system.It is able to not only solve problems that the identification algorithms require heavy computational burden for a lareg-scale systems with many parameters and high dimensions problem,but also solve identification problems for bilinear-parameter systems,multi-linear-parameter systems and nonlinear systems with complex structures.In this paper,firstly we describe the hierarchical identification principle,the Jacobi iteration and Gauss-Seidel iteration for linear systems with a set of equations Ax=b,and give the family of iterative methods for linear equations;secondly,we study hierarchical least squares based and hierarchical gradient based iterative algorithms for general matrix equations and coupled matrix equations in the light of the Jacobi iteration and the hierarchical identification principle;thirdly,we present a two-stage recursive least squares algorithm(i.e.,a simple hierarchical least squares algorithm) for equation error models and a hierarchical least squares identification algorithm for linear regression models.Finally,the hierarchical identification methods are introdiced for multivariable CARMA-like systems using the hierarchical identification principle.

Abstract:Based on precipitable water vapor retrieved from ground-based GPS,data of ground automatic meteorological stations and conventional weather data,the evolution tendency of precipitable water vapor and ground pseudo-equivalent temperature during a heavy rain in south central Hebei province is studied.The results show that the heavy rainfall are caused by warm-wet flowing and shear line at the edge of subtropical high,and the precipitation area is between 584 to 588 dagpm lines in 500 hPa,between shear line in 700 to 850 hPa.Rainfall usually occurs when the GPS-retrieved precipitable water vapor is higher than the average value,especially near its maximum value,and the heavy rain period is corresponding to the maximum value stage of precipitable water vapor.Rainfall occurred more often when the deviation coefficient of GPS-retrieved precipitable water vapor is positive,heavy rainfall generally happens while deviation coefficient is higher than 1.For the same station,when GPS-retrieved precipitable water vapor is high,the real precipitation is strong.While for the different stations,the high precipitation is not necessarily represent strong real rainfall,for it is corresponding to the station location and altitude.High-energy accumulation is a necessary condition of rainfall.The rainfall of subtropical high usually occurs in the rapid decline phase of pseudo-equivalent temperature or its valley areas.The precipitation will be stronger when pseudo-equivalent temperature is at high peak,in sharp movement and with long duration of high value.

Abstract:Based on NCEP 2.5°×2.5°reanalysis data of wind and daily station precipitation data from 1998 to 2008,a regular pattern is found that when there is a heavy rain in Shanghai,10—20 day LFO zonal wind along 30°N in East China becomes stronger than normal and there is 10—20 day LFO southerly wind in Fujian and Zhejiang coastal area at the same time.So define the two areas as influencing areas.After doing lag correlation analysis with 10—20 day LFO wind in whole field and 10—20 day LFO zonal and meridional wind of the two influencing areas separately,two key areas are found,which are area 110°—130°E,0°—10°N and area 160°—140°W,45°—55°N respectively.It is found that 10—20 day LFO zonal wind propagates from area 110°—130°E,0°—10°N to the region around Shanghai and 10—20 day LFO meridional wind propagates from area 160°—140°W,45°—55°N to Shanghai.Therefore through LFO propagation,10—20 day LFO wind of the two key areas would influence the weather of Shanghai area.Results also show that 10—20 day LFO zonal wind and 10—20 day LFO meridional wind of the two key areas have a good relationship with precipitation of Shanghai 15—20 days later.Prediction test shows that the 10—20 day LFO wind in the two key areas can be good indicators of extended range forecast of summer precipitation in Shanghai.

Abstract:In order to avoid the approximation of spheroid surface as flat plane in calculation of sampling volume,the differential theory is applied to derive the expression of effective sampling volume for bistatic weather radar system.It is proved that the ratio of the bistatic resolution volume to the monostatic resolution volume,or V_b/V_m,numerically equals the derivative of the polar axis length (R_t) to the semi-major axis length (a) in the bistatic radar system.Though the result from numerical calculation for sampling volume is the same as that from references,approximations performed to obtain the expression has been eased and the derivation process is theoretically strict and easy to understand.Some relationship expressions between the geometric elements for bistatic polarization radar system,such as the ratio V_b/V_m,the radius R_t and co-plane azimuth Φ for the transmitter,the radius Rr and co-plane azimuth Φ_r for the receiver,and the bistatic angle β,are obtained.The features of effective sampling volume variation with the related geometric elements are analyzed.The results provide a theoretical base for bistatic polarization weather radar antenna control,data processing,sidelobe contamination elimination and detecting accuracy improvement.

Abstract:For data transmission of mobile Doppler weather radar,the consultation for emergency communication,and the broadcast of major weather process,a meteorological satellite communication system based on DVB/IP was designed,which integrates several high technologies including satellite communications,computer network,wireless communication,multimedia production,image transmission and so on.Considering the requirements of meterological disaster prevention and mitigation,the data collection and communicaton function of the system can provide technical support for meteorological emergency management and decision-making process.The application of this system will improve the emergency response capability of Shanghai Meteorological Bureau.

Abstract:By using the thunderstorm observation data from 1980 to 2010 of Linxia station in the northeast side of Qinghai-Tibet Plateau and the lightning data from 2006 to 2010 in the middle area of Gansu,thunderstorm and lightning characteristics such as inter-annual variation,annual variation,diurnal variation,directions of first thunderstorm,cloud-to-ground lightning density,etc were analyzed.The results of this paper found the formation characteristics of thunderstorm and lightning:the thunderstorms and lightning mainly happened in the summer and afternoon;the cloud-to-ground lightning density is higher than the average densities in China.This research will be useful to prevention and mitigation of disasters.

Abstract:Due to the serious impact of the noise component contained in reference signal on Differential Transmitted Reference(DTR) receiver's performance,the paper proposes the Modified Reference Differential Transmitted Reference(MRDTR) autocorrelation receiver for Impulse Radio Ultra-WideBand(IR-UWB) wireless communication systems.This receiver sums up the reference signals in every frame during the previous symbol interval and then averages them to form the new reference signal.The noise effect on the receiver performance is reduced by the average method.Then the received signals in each frame during the current symbol interval are multiplied with the new reference signal and the products are integrated.These integral results in every frame are summed up and the sum is decided to recover the transmitted symbol.The Bit Error Rate(BER) performance of the receiver is improved by constructing the new reference signal.Its BER performance is analyzed over resoluble multipath channel.Theoretic analysis and simulation results verify that the BER performance of the MRDTR receiver is superior to DTR receiver evidently.

Abstract:Grid connects distributed resource into a mass environment for computing.The scheduling algorithm has much influence over the efficiency and performance of grid.EASY-backfill is a classical scheduling algorithm with simple program,little computation workload and relatively high performance.But the algorithm is based on assumptions that all resources in the grid are absolutely stable,and the performance forecast of jobs is accurate and reliable.Yet these conditions are ideal and unpractical.In this paper,we use some unstable parameters to build a different model of unstable grid resources,and modify the EASY-backfill algorithm according to the model.We make effort to keep the performance and effectiveness of the algorithm on condition that the modified algorithm sensitive to the unstable and unpredictable grid resource.We also make comparison between the classical and modified algorithm and do some discussion on the influence of different unstable parameters.

Abstract:Most applications in modern enterprises will provide a set of authentication method of their own,which increase the user's burden and reduce the system security as well.Another serious problem is how to administer access requests of authenticated users.The Single Sign-On(SSO) based on SAML and access control based on XACML can provide a solution for these two problems.Based on the analysis of SAML and XACML specifications,an SSO model based on SAML and XACML is proposed in this paper,and applied on the platform of Microsoft.NET.The model shares user information including ID authentication and access level,which promote interoperability between different security systems and guarantees access control as well.The security of the model is also analyzed.

Abstract:The data flow characteristics in downstream transmission of Ethernet Passive Optical Network (EPON),which is integrated with burst access mode,are analyzed in this paper,and a downstream transmission scheme based on optical burst switching is proposed hereby.The bursting arrival of data frames from Optical Line Terminal (OLT) will fully occupy the downlink bandwidth,thus delay the transmission of data frame with higher priority,and overload the Optical Network Unit (ONU).The influences of burst arriving data frames on the transmission of higher-priority data frames can be reduced through scheduling the downlink bandwidth resources based on priority.The sliding windows are used to regulate the arrival rate of each ONU data frame to relieve the overload of ONU processing.The transmission scheme is simulated and evaluated on OPNET Modeler.The results verify the feasibility of the scheme.

Abstract:In this paper,the uniform boundedness and uniform ultimate boundedness of the stochastic retarded differential equations is investigated.The new Razumikhin theorems of boundedness about these systems are obtained by using the Lyapunove functions and Razumikhin technique.It should be noted that the boundedness criteria prove the global existence of solutions as well as boundedness,thus the available results in references are improved.Finally,an example is illustrated to verify the theorems.

Abstract:In this paper,adaptive synchronization of one modified smooth Chua's circuits is discussed.When the parameter of the master system is unknown to that of the slave system,an adaptive controller is designed to realize the synchronization of the two systems by using Lyapunov stability theorem and adaptive control method.The effectiveness of the controller is verified by Matlab simulation.

Abstract:In this paper,we prove that an Artinian algera A satisfies the Gorenstein projective conjecture if the left finistic dimension or the right finistic dimension of A is finite.As a result,the Gorenstein projective conjecture is proved to be true for Gorenstein algebras and algebras with representation dimension less than or equal to 3.