Abstract:This paper discusses the computational efficiency of the determinant,the matrix inversion and the block matrix inversion.For the multivariable systems with coupled information vectors,we study the subsystem recursive least squares (RLS) identification algorithm and the joint RLS identification agorithm with less computation are studied.For the multivariable systems the partially coupled information vectors,the subsystem least squares identification algorithm and the block matrix inversion based least squares identification algorithm are presented and the subsystem RLS identification algorithm and the identification model decomposition based RLS identification algorithm are proposed.Finally,the comptutational efficiency of the proposed algorithms is analyzed.

Abstract:Based on the ground-based observation data from 147 meteorological stations in nearly 50 years over the Yangtze River basin,applying climatology computational method for estimating global solar radiation,variation relationship between global solar radiation and 20 cm pan evaporation was contrasted and analyzed from 1960 to 2007.The main results are as follows:significant negative trend of global solar radiation and pan evaporation were detected in the upper,middle and lower reaches.Significant positive correlation existed between the global solar radiation and 20 cm pan evaporation,and the pan evaporation varies accordingly with the fluctuation of global solar radiation.The correlation coefficient between global solar radiation and pan evaporation in lower reach is higher than that in upper-middle reaches.In term of the seasonal variation,the research result indicates the same trend as the annual variation,and the variation of both global solar radiation and pan evaporation showed significant negative trend in four seasons of the whole basin,especially in spring,summer and autumn,which contributes most to the decrease of pan evaporation in a year.Therefore,the significant negative trends in global solar radiation over the basin can be considered one reason that causes the decrease in pan evaporation.

Abstract:With the lightning positioning data from 2007—2010 measured by 52 lightning detection stations of 5 provinces in central China,this paper analyzes the daily change,intensity,slope and density of lightning distribution for four seasons.The results show that the occurrence time of the positive and negative lightning peak value and their daily variation curve for four seasons are not identical.The lightning mostly occurs in the period from afternoon to evening (12:00—20:00) during summer and autumn,which presents a single peak change,and the peak value usually appears in 16:00—18:00.While during winter and spring,the lightning mostly occurs in the period from evening to before dawn (20:00—2:00),which presents a single trough change,and the valley value appears in 10:00—14:00.Lightning intensity and slope change little during four seasons.The intensity and slope of positive lightning are higher than that of negative lightning,and the highest lightning slope appears in summer,while the biggest lightning intensity appears in winter.The positive and negative lightning intensity mainly distributes in 10-40 kA,more than 90％ of lightning intensities are less than 80 kA,and 95.5％ of lightning intensities are less than 100 kA.There is considerable variation in seasonal lightning density distribution in the five provinces.During spring,the lightning density is higher in central part than in north and south part,and in summer and winter,the lightning density increases gradually from south to north,while in autumn,it increases gradually from north to south in the five provinces.

Abstract:With the rapid development of wind power technology,the power generation capacity of single machine is increasing and the wind turbine height has been increased to 100 meters.However,the lightning strike risk suffered by the wind turbine also increased.This paper analyzes the mechanisms of lightning strike damage on wind turbine blades,explains the causes and formation of blade damage after lightning strike through examples,and summarizes the characteristics of large turbine blade and environmental factors of wind farm.Some improvements on wind turbine against lightning risk are proposed based on warning data of atmospheric electric field instrument and combined with the latest plasma lightning protection technology.The concept of active lightning protection of wind turbine is proposed,with the purpose to promote development of new lightning protection technology.

Abstract:The temperature and humidity characteristics of humidity sensor on China-made GPS and RS92 radiosounding system are studied through a modified test method under controlled temperature and humidity environment in a laboratory.The results show that hysteretic detection occurred under low temperature,especially during the process of humidity increase,which brings obvious error to the dynamic measurement of aerological humidity.The change of airflow also influences the humidity measurement.The obtained results are useful for the modification of humidity measurement algorithm of radiosounding sensor,and the improvement of the measurement performance of aerological humidity sensor.

Abstract:The high-precise measurement of temperature is always the important technology of automatic weather station (AWS) design.Multiplexer CD4052 is widely used in data acquisition unit (DAU) design,which is a most important part of AWS.Until now,there is still a lack in research on the impact of offset current and temperature characteristics of CD4052 in temperature measurement.This paper focuses on the impact of CD4052 offset current for temperature measurement.Study results show that the offset current has important influence on temperature measurement error,and the error is significantly correlated with environmental temperature.The results are valuable in theoretical basis and engineering application for design and offset of DAU.

Abstract:The traditional BP neural network algorithm is good in learning ability and fault tolerance,while its disadvantages such as slow convergence rate and easily falling into local minimum restrict its further development and application.An improved BP algorithm with self-adaptive learning rate and additional momentum factors can effectively reduce the training time,speed up the convergence rate and inhibit the possibility of falling into a local minimum.The improved algorithm is applied to the image character recognition system.The influences of model parameters on performance of BP neural network are analyzed,and the recognition results are given after a series of parameter optimization.The experimental results show that the improved BP neural network can recognize image characters with high accuracy and robustness.

Abstract:A hybrid square contour algorithm for 16QAM signals is proposed.By judging whether the output signals are in the judgement domain of the constellation points and switching the algorithm between the square contour algorithm (SCA) and decision-directed (DD),this algorithm can recover the phase and reduce the Intersymbol Interference (ISI).Simulation results with underwater acoustic channel verify the significant improvements of the proposed algorithm in the convergence rate and ISI as compared with the conventional SCA.The ISI of the proposed algorithm is low,thus can provide underwater acoustic channel with significant equalization ability.

Abstract:In microphone arrays application,it is difficult to localize sound source accurately and quickly in a noisy and reverberant environment.In order to solve this problem,many researchers have presented different approaches.The steered response power-phase transform weighted(SRP-PHAT) source localization algorithm has been proved robust,however,it requires high computation cost for searching the peak of steered response power in a large location space.Thus,an improved SRP-PHAT method using an orthogonal linear array was presented in this paper,which reduced a two-dimension searching space to a couple of one-dimension ones.Then the parameters of direction of arrival(DOA) were separated,and computed respectively in the one-dimension searching space with coarse-fine strategies of hierarchical search.This algorithm was based on the observation that the wavelengths of the sound from a speech source are comparable to the dimensions of the space being searched and that the source was broadband.A systematic series of comparisons with previous algorithms were made basing on Matlab.Simulations show that the main computational load of SRP-PHAT algorithms has been greatly cut down,and there is no loss in accuracy in the proposed method.The performance of the algorithm can be further improved by using constraints from computer vision.

Abstract:Optical code division multiple access(OCDMA) offers all-optical processing,asynchronous access ability,and high potential information security.Passive optical network(PON) provides a solution for last mile bottleneck in optical access network.OCDMA-PON integrates the advantages of OCDMA and technological features of PON.It has great potential in future application of optical access network.In this paper,the theory of OCDMA-PON system and the principle of FBG-based en/decoder are introduced.A transmission experiment is designed with two-dimensional optical orthogonal code(2D-OOC),consisting of four transmitters and one receiver,and the data transmission rate is 2.5 Gb/s.The experimental result shows that in the case of multi-user,the system realizes correct transmission and reaches good performance.

Abstract:This paper considers a new tracking control problem for a class of multivariate non-Gaussian system where the tracked target is a given joint probability density function.The control objective is to find an algorithm such that the entropy of tracking error is minimized.A function based model is established between the disturbance,state and error.A recursive optimization approach is presented such that the performance index is minimized.Finally,simulations are provided to demonstrate the effectiveness of the proposed minimum entropy control algorithm.

Abstract:To find the robust matching points between different views on the same object is the key step in a computer vision system in practice.The popular SIFT (Scale Invariant Feature Transforms) has showed its power for robust feature points matching.However,the edge and corner points are not included in the SIFT matching points.Considering the fact that the corner points represent the structure information of an object,we hence propose a robust approach for corner matching via SIFT.This new approach improves the robustness while decreases the computing burden in matching.A series of experiments on corner points matching illustrate that the proposed approach is not sensitive to changes in view,rotation or scale,and robust to noise interference.

Abstract:A novel method is proposed to generate rabbit sequence and realized by C programming,which can generate lots of 0—1 sequences by selecting different starting points.The sequences can be well applied to watermarking decision.Furthermore,the method vividly display the generating process of rabbit sequence,which reflects the dynamic storage characteristics of linked lists.Thus,the method can be used as a case in course teaching of data structure or program design.

Abstract:A diode laser end-pumped Nd:YVO₄/KTP solid laser experimental system is built.The system starts from a single diode laser with center output wavelength at 808.5 nm to end-pump Nd:YVO₄ laser crystal and produce 1 064 nm infrared laser,which is then swithed to 532 nm green laser through intracavity frequency-doubling by a KTP crystal inside the laser cavity.The relationship between 808.5 nm diode laser output power and the injection current,and the relationship between diode laser pump power and 532 nm green laser output power is studied by experiments.The influencing factors of the 532 nm green laser output power,including the phase-matching angle of KTP frequency-doubling crystal,the pump laser focus to the Nd:YVO₄ laser crystal position,and the length of solid-state laser cavity are also studied and analyzed.The experimental results demonstrate that the output power of 532 nm green light can be enhanced through increasing the pump diode laser output power,or decreasign the length of solid laser cavity,or turning the pump diode laser focus into the Nd:YVO₄ laser crystal,or adjusting the KTP crystal phase-matching angle correctly.

Abstract:We propose a new reconstruction scheme for the backward heat conduction problem with second kind boundary in bounded domain.The convergence analysis depending on the strategy of choosing regularizing parameters is given.Numerical implementations are presented to show the validity and numerical stability of this new scheme.

Abstract:We propose a linearized compact difference scheme for the nonlinear Schrödinger equation.The existence of the difference solution is proved by Brouwer fixed point theorem.It is proved by the discrete energy method and the method of mathematical induction that the new scheme is uniquely solvable and convergent with fourth-order in x-direction and second-order in t-direction.Numerical results verify the precision and numerical stability of the proposed scheme.

Abstract:An evaluation algorithm is proposed to calculate the air-condtioning cooling load and the resulting power consumption in summer.A regression model between the cooling load and the daily maximum temperature in summer is built in accordance with actual temperature variation in summer of 2012,therefore the added cooling load stimulated by per degree of temperature increase is analyzed.An example of cooling load and power consumption in summer of China's main power grids is given to verify the feasibility of the proposed algorithm,which can provide reference for rational management and effective marketing of power grids.