Abstract:System identification is the theory and methods of establishing mathematical models of systems.The mathematical modeling has a long research history,but the system identification discipline has only several tens of years.In this short decades,system identification has achieved great developments,new identification methods are born one after another,and the research results cover the theory and applications of natural science and social sciences,including physics,biology,earth science,meteorology,computer science,economics,psychology,political science and so on.In this context,we come back to ponder some basic problems of system identification,which is not without benefits for the development of system identification.This is a paper of an introduction to system identification which briefly introduces the definition of identification,system models and identification models,the basic steps and purposes of identification,including the experimental design of identification and data preprocessing,and the types of identification methods,including the least squares identification methods,gradient identification methods,auxiliary model based identification methods,and multiinnovation identification methods,and hierarchical identification methods,etc

Abstract:In order to solve the sudoku more efficiently,a novel approach was proposed.We employed the realnumber coding to get rid of the integer constraint,meanwhile used the L0norm to guarantee the sparsity of the solution.Moreover,the L1norm was used to approximate the L0norm on the basis of RIP and KGG condition.Finally,the slack vectors were introduced to transfer the L1norm into a convex linear programming problem,which was solved by the primaldual interior point method.Experiments demonstrate that this algorithm reach 100％ success rate on easy,medium,difficult,and evil levels,and reach 864％ success rate on only 17clue sudokus.Besides,the average computation time is quite short,and has nothing to do with the difficulty of sudoku itself.In all,this algorithm is superior to both constraint programming and Sinkhorn algorithm in terms of success rate and computation time.

Abstract:Based on the data of daily frost and air temperature in 1960—2008 from 240 stations,we analyze the temporal and spatial distribution of frost in southern China using regression analysis,accumulative anomaly,discrete power spectrum,correlation analysis,and GIS spatial analysis function.The result shows that in terms of the temporal variation,annual average freezing days gradually increase during 1960—1986 and rapidly decrease during 1987—2008.Frost mainly occurs in January,December and February.The potential cycles are mainly mediumlong cycles,such as 490,245,163 and 41 a.In terms of the spatial distribution,frost frequency and intensity show distinct latitudinal zonation and vertical zonation,which decrease with latitude and are higher in the east and west than in the middle of southern China.

Abstract:A novel terahertz modulator based on photonic crystal is presented.The modulator combines the structure of line defect and point defect,and is designed to be tunable by filling the point defect with nonlinear material GaAs.Without external pumplight,there is defect mode in the point defect.While by applying external pumplight to the defect with specific wavelength and intensity,the defect mode in the two defects \soutwill disappears.Based on this mechanism,the device can modulates the onoff state of the terahertz wave in specific wavelength.The numerical simulation results show that this THz modulator has a extinction ratio of more than 5110 dB,responses within dozens of picoseconds,and has a small size and is easy to integrate.

Abstract:This paper designs a DTWbased speech recognition system.The method applied in this paper belongs to the small glossarys isolated words speech recognition,which includes starting & ending point measuring,feature extraction and mode matching.The system takes preprocess of the speech signal,and then adopts the MFCC as a characteristic parameter drawing algorithm,and takes the DTW as the recognition algorithm,uses an improved template training technique to extracts the reference template with only a small quantity of samples by computing the average length.An experiment with speech signal recorded in labenvironment is given to simulate the proposed speech recognition method.The simulation results show that compared with using a single reference template,this method improves the recognition accuracy and the robustness.Furthermore,compared with the VQ,our method needs fewer samples and reduces the complexity of the algorithm.

Abstract:According to the characteristics of Doppler velocity sonar of underwater vehicle integrated navigation system,a novel method of multiresolution analysis based on translation invariant discrete wavelet transform was proposed.Doppler frequency drift can be accurately estimated under low signal／noise ratio with semisoft threshold filtering using Daubechies wavelet function.The original signal can then be acquired from the composite signal.Simulation experiments show that 4 wavelets deposition method improves the filtering effect greatly with calculation quantity reduction,and the Doppler noise can be eliminated efficiently with the wavelet transform method,thus improve the navigation accuracy of underwater vehicle integrated navigation system.

Abstract:As an important dimensional parameter,wheel center is always measured manually,therefore a high precision measurement method based on stereo vision is proposed in this paper.The edge grouped algorithm and ellipse fitting algorithm are applied to extract the circle shape of the steel ring,then the subsection stereo matching algorithm is used to acquire the 3D coordinate of interest points in the circle shape.Finally through the 3D plane fitting algorithm,coordinate transformation algorithm and circle fitting algorithm,the 3D coordinate of the wheel center is calculated.Measurement experiment results show that the method can acquire the 3D coordinate of the wheel center efficiently,thus lay a foundation for other vehicle parameter measurement.

Abstract:IIC bus is simulated by C51 program according to its time sequence.Based on this simulated IIC bus,a voltage measurement system is designed by the single chip microcomputer and 8bit A/D and D/A converter PCF8591.The PCF8591 is a singlechip,singlesupply low power 8bit CMOS data acquisition device with four analog inputs,one analog output and a serial IIC bus interface.Three address pins A0,A1 and A2 are used for programming the hardware address,allowing the use of up to eight devices connected to the IIC bus without additional hardware.Address,control and data to and from the device are transferred serially via the twoline bidirectional IIC bus.The functions of the PCF8591 include analog input multiplexing,onchip track and hold function,8bit analogtodigital conversion and an 8bit digitaltoanalog conversion.The maximum conversion rate is given by the maximum speed of the IIC bus.The circuit and main program flow chart are proposed in this paper.The system has simple structure and strong expandability owes to the IIC bus.It provides reference for the application of IIC bus in acquisition system.