Table of Content

15 March 2015 Volume 28 Issue 3
    A Novel Image Denoising Method Based on Structural Similarity
    YU Ting
    . 2015, 28(3):  1. 
    Abstract ( 666 )   PDF (1147KB) ( 522 )  
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    In this paper,we make one of the first attempts to incorporate the structural similarity as the fidelity term into the framework of image denoising in order to overcome the weakness that the fidelity term of the classical ROF model does not consider image structure,which leads to poor visual image restoration.This paper first proposes a new image denoising model (model 1) by introducing structural similarity as the fidelity term instead of the original.In promotion model 2,a nonconvex regularization rather than the classical TV regularization is used to preserve the edge better while removing noises.Experimental results show model 1 and model 2 achieve better performance than ROF model in image structural information and perceptual image quality.And model 2 plays a more important role in preserving image edge than model 1.

    Library Automatic Borrowing and Returning System Design Based on RFID
    XIAO Yadi,HE Chengjia,LI Liping
    . 2015, 28(3):  7. 
    Abstract ( 621 )   PDF (766KB) ( 483 )  
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    By analyzing the existing problems of automatic management systems of libraries,this paper proposes an automatic recording and control scheme based on RFID technology.A miniature,portable and automatic machine for book borrowing and returning is also designed.This system consists of the RFID reader,the MCU,the SD card and the LCD display.Circuit testing shows that it realizes the functions of automatic book borrowing,returning and locating.This research offers new approach to better management of small libraries.

    Falling Detection Method Based on Axis Acceleration
    LI Zheng
    . 2015, 28(3):  11. 
    Abstract ( 583 )   PDF (945KB) ( 486 )  
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    This paper presents a new falling detecting method based on three-axis acceleration signal and pattern recognition.This method uses an acceleration sensor named MMA7260Q.When falling happens,the three-axis signal is involved in a huge signal area,and therefore the method uses the peak value of acceleration and the curve of acceleration energy to generate three-axis acceleration signal.This method can avoid the error caused by the changes of angle when falling happens.According to the result of experiments,using the method presented in this paper,the accuracy of falling detection is up to more than 90%.

    Front Obstacle Detection Based on Shadow of Chassis
    ZHAO Richeng
    . 2015, 28(3):  15. 
    Abstract ( 646 )   PDF (825KB) ( 454 )  
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    Vehicle intelligent auxiliary drive system is an important part of the intelligent transport system.Using the computer vision to detect moving vehicle is the essential problem of the intelligent vehicle navigation.Real time detection of the location information of the preceding vehicle detection is the premise for security driving.A detection method for preceding vehicles based on the shadow of chassis is presented.The key thought is using the detection of the shadow to detect the preceding vehicle with the lane detection.First,the Otsu threshold segmentation is used to extract the lane and generate the AOI.Then,two adaptive thresholds are adopted to extract the interesting lines of the chassis and the road so that the moving vehicle is detected.The experiment on highway shows that this algorithm satisfies the need of the security driving,and can exactly detect the preceding moving vehicle thus reducing the risks of traffic accidents.

    Application of Multi-threading Technology in LabWindows/CVI
    YANG Qiuhu
    . 2015, 28(3):  19. 
    Abstract ( 591 )   PDF (734KB) ( 566 )  
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    Multi-threading technology of LabWindows/CVI ensures the implementation of the concurrent tasks.The multi-threading technology resolves the conflicts between concurrent tasks and improves the work efficiency greatly.LabWindows/CVI provides more data protection mechanisms for data sharing and transfer.The mechanisms and its implementation methods are described in the paper.Multi-threading is used to design the automated instrument control interface.The experimental result shows that the multi-threading technology has a good application in the concurrent tasks system.

    Design and Implementation of Wireless Control Program for PC Screen Lock/Unlock
    XING Haifeng
    . 2015, 28(3):  22. 
    Abstract ( 590 )   PDF (785KB) ( 507 )  
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    This Paper provides an implement for locking or unlocking screen in a wireless manner based on the Socket transmission.The control program is completed by using both C and Java,and deployed both in Android system and PC system successfully.The program inhibits illegal use of PC,thus protecting the personal information.

    Implementation of De-interlacing Algorithm on FPGA
    ZHOU Wenbin
    . 2015, 28(3):  27. 
    Abstract ( 519 )   PDF (675KB) ( 465 )  
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    This paper proposes a de-interlacing algorithm based on motion detection.The theory is to divide the image into static part and motion part by the 4-field based horizontal motion detection and intra-field interpolation detection,and then the front-field value and intra-field interpolation are adopted for de-interlacing.The proposed algorithm is implemented by FPGA and the result is displayed on VGA.By observing the image,we can conclude that the proposed arithmetic can remove flaws like blur and zigzag effectively,contributing to a good effect.

    Linear Mixed Effects State Space Model Based on Monte Carlo Method
    TANG Aiping
    . 2015, 28(3):  30. 
    Abstract ( 645 )   PDF (578KB) ( 444 )  
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    A novel statistical inference method for linear mixed-effects state space model (MESSM) is proposed.The combination of Sequential Monte Carlo Algorithm and Kalman Filter achieves the state estimation under the assumption that the random effects are unknown and the population parameters known.Finally a comparison of Monte Carlo filter and Kalman filter based on simulated data validates the efficacy of the algorithm.

    Insect Classification Based on the Theory of the ELM
    XU Yuanhao,QI Huanfang
    . 2015, 28(3):  33. 
    Abstract ( 609 )   PDF (868KB) ( 399 )  
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    Applied in the field of insect taxonomy,machine vision technology displaces the human eye observation identification process and improves working efficiency.The automatic identification technology has two main steps:insects feature extraction and classifier design.Based on the entire identification process,this paper puts forward an insect identification method based on hybrid features of ELM theory.In the feature extraction stage,the hybrid features will be extracted including the color,morphological characteristics,spatial texture,and spectral texture;while in the classifier design stage,high learning speed and good generalization performance ELM extreme learning machine are taken.The experimental results show that this method offers an insect identification accuracy up to 97% with a short classifier training time,superior to the traditional automatic identification method.

    Aluminum Oxide Energy Consumption Computing Method Based on Neural Network
    LUO Mingqiang,LIANG Peng
    . 2015, 28(3):  38. 
    Abstract ( 668 )   PDF (713KB) ( 500 )  
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    The energy consumption calculation of aluminum production surface oxidation is very complicated due to many influencing factors,such as multi-type product and inconsistent calculation standard (size,weight,and thickness),etc.In order to solve these problems,this paper proposes an aluminum oxide energy consumption computing method based on neural network.We first train the neural network by using historical data and calculate the influence of the oxidation factor on the coefficient of oxidation.Then the coefficients of oxidation of the batches of oxidation and production energy consumption are calculated according to the trained neural network.Finally,we verify the effectiveness of proposed method by comparing the calculated production energy consumption with the measured data.The experimental result shows that our method can find abnormal energy loss,improper production parameters in the production.

    Flood Forecasting Model Based on Improved BP Neural Network
    GAO Liyuan,DONG Jia
    . 2015, 28(3):  41. 
    Abstract ( 698 )   PDF (684KB) ( 499 )  
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    BP neural network is good at forecast data model.This article presents an improved BP network by the introduction of the genetic algorithm.A comparison of the two algorithms is made in terms of processes and efficiency,and both are tested using the flood forecast model.Test results and error analysis show that genetic-BP network is better in efficiency than original BP network and worth promotion in the practical engineering.

    Multidimensional Parameter Estimation Based on DML-ESPRIT Algorithm Fast Joint
    LUO Zheng,ZHANG Min,LIU Yuan
    . 2015, 28(3):  44. 
    Abstract ( 654 )   PDF (975KB) ( 485 )  
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    By organically integrating the joint multidimensional parameters estimation ability of deterministic maximum likelihood (DML) estimation criterion and the computation efficiency of estimating signal parameters via rotational invariance techniques (ESPRIT),a novel joint two-dimensional DOA (2-D DOA),power and frequency fast estimation algorithm named DML-ESPRIT is proposed.Firstly,based on the special characteristics of double L-shaped array,we introduce the space cone angle to represent the source's 2-D DOA.This operation successfully converts the multidimensional space searching problem into the separated one-dimensional angle estimation.Under the DML estimation criterion,the joint estimation model of parameters such as space cone angle,signal power and frequency is established.Then TLS-ESPRIT method which could avoid the spectrum peak search is used to solve the model.On the premise of keeping estimation precision,the time consumption of DML-ESPRIT algorithm is only about 35 ms on the average,thus good prospects for engineering applications.

    Distributed Trust Model Based on Multi-factor Trust
    CHEN Shuxiao
    . 2015, 28(3):  50. 
    Abstract ( 662 )   PDF (840KB) ( 557 )  
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    A distributed trust model is proposed based on multi-factor trust.The proposed trust model introduces an aging function to distinguish the importance of trust in different time.When calculating the comprehensive trust value of nodes,the model increases the trust of energy by analyzing the residual energy of node.Also,the model combines the trust of communication and the trust of energy and properly adjusts the size of the weight between communication trust and energy trust to evaluate the credibility of sensor nodes.Simulation experiment and analysis shows that this model can quickly identify malicious nodes with improves successful rate of trading by nodes and security of information in the network system when compared with other models.

    Research into and Implement of MUSIC Algorithm and its Improvement
    HUANG Liwei,CHEN Huiqin,CHEN Yulin
    . 2015, 28(3):  55. 
    Abstract ( 1000 )   PDF (635KB) ( 552 )  
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    This paper studies several kinds of MUSIC algorithms for the arrival (DOA) estimation of signals,which is an important branch in array signal processing.The theories of classical MUSIC algorithm,Forward/Backward spatial smoothing MUSIC algorithm,and modified MUSIC algorithm are expounded.Simulation by Matlab shows that classical MUSIC algorithms are good in performance for estimating the doas of incoherent sources,but fails for coherent sources;the Forward/Backward spatial smoothing MUSIC algorithm decreases the source number,and increases the amount of calculation;modified MUSIC algorithm offer the best performance without affecting the estimation of relevant source or significant increase in the amount of calculation.These algorithms for the doas estimation have their own advantages and disadvantages.

    Inverted Pendulum System Based on T-S Fuzy Model
    WANG Xueyan
    . 2015, 28(3):  58. 
    Abstract ( 478 )   PDF (634KB) ( 555 )  
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    In this paper a nonlinear mathematic model for linear single IPS is built,taking advantage of classical mechanics.We use Matlab to qualitatively analyze the system based on equations of motion for the IPS.The controller is designed by pole assignment and LQR,and the effects of all parameters on the system control are evaluated.Given the nonlinear property of the IPS,we study the principles in variable structure control (VSS) among nonlinear controlling approaches,and design the controller.

    A Fast and Efficient Artificial Bee Colony Algorithm
    WANG Xiaojuan
    . 2015, 28(3):  61. 
    Abstract ( 635 )   PDF (695KB) ( 516 )  
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    For the slow convergence and susceptibility to local minima of the artificial bee colony algorithm,a hybrid search strategy based on multi-dimensional search and linear search in the employment bee search is presented,which improves convergence rate of the algorithm under single one-dimensional search strategy.A new selection strategy for following the bees is also proposed to enhance the diversity of population and strengthen global searching ability.Finally,the improved algorithm is compared with standard algorithms through simulation experiment on twelve benchmark test functions,the results show that the improved algorithm outperform the standard algorithm in both convergence rate and searching precision.

    A Resilience Evaluation Model
    YIN Jindi
    . 2015, 28(3):  65. 
    Abstract ( 665 )   PDF (739KB) ( 447 )  
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    The establishment of a reasonable model to evaluate and quantify the elasticity offers great help in future forecast and decision.In this paper,a number of service attribute indexes are sett,the corresponding performance score calculated introduced,and the adaptive score and the service state of a single service given based on a set of performance scores.And finally combined with the Markov network model and elastic function equations,the whole network resilience is evaluated.This paper considers not only the single service condition,but also the mutual dependencies between services.It is of referential value in the future network elasticity measurement,fast search for fault,and state threshold setting.

    Numerical Simulations of Strong Solutions to Several Reflected Stochastic Differential Equation
    CHAI Chen,LIU Min
    . 2015, 28(3):  69. 
    Abstract ( 516 )   PDF (554KB) ( 442 )  
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    Reflected stochastic differential equations are widely applicable in queuing theory,banking and insurance,storage system modeling,and computer network.In this paper,we first review the form and the definition of the solution to reflected stochastic differential equation.Then we apply the numerical idea of non-reflected stochastic differential equation to reflected cases.The Euler-Maruyama algorithm,the Euler-Peano algorithm and the penalization algorithm are proposed to study the numerical solutions to the reflected stochastic differential equation.Finally,taking the Ornstein-Uhlenbeck process and reflected Ornstein-Uhlenbeck process as examples,we perform simulations and compare the results of the above algorithms.The results show that the proposed algorithms have good prospects in the practical applications of option pricing,term structure of interest rates,financial risk calculation and the modeling of controlled financial markets.

    Maximum Delay of Two-person Cooperative Scheduling Games
    QIU Yanling
    . 2015, 28(3):  72. 
    Abstract ( 586 )   PDF (663KB) ( 454 )  
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    In the real activities,it is often the case that a job requires the cooperation of more than one person.In this paper,we study the case in which there are some jobs for two persons to complete by cooperation,each job requiring the same processing time and each person having only one machine used for machining.This is a two-person cooperation scheduling games with the minimum of maximum delay as the processing cost.In building the model,both the efficiency of cooperative parties and the fairness principle are considered.By determining a proper division of this batch of parts,the jobs will be distributed to two machines,and thus the corresponding cooperation income distribution is reasonable and can be accepted by both sides.Firstly this paper analyzes the existence and the number of the optimal solutions of the model.Several numerical examples are used to verify the validity of the model.

    TCP Communications of One Sever to Several Clients Based on Qt
    HUANG Pian,ZHANG Qiong,ZHU Ting
    . 2015, 28(3):  76. 
    Abstract ( 1015 )   PDF (819KB) ( 557 )  
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    As a good cross-platform application and UI development framework,Qt is increasingly used in application development,in which the web application is one of the main aspects.This paper discusses the use of Qt to develop the procedures of TCP network.The server and socket connection are established by using new Qt encapsulated TCPServer class and TCPSocket class inherited from QTCPServer class and QTCPSocket class respectively,so as to realize the set for the server to several clients.

    Natural Gradient Algorithm for Blind Source Separation with Unknown Source Number
    SHAO Lianlian
    . 2015, 28(3):  79. 
    Abstract ( 697 )   PDF (751KB) ( 462 )  
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    A summary of the natural gradient algorithm for blind source separation with an unknown number of sources is presented and the conclusion is drawn that it is the redundant movement of separating matrix in the zero space of the transpose of mixing matrix that causes the divergence.By the projected natural gradient algorithm,we theoretically prove that with the increase in the number of iterations,the norm of the redundant subjects to an exponential distribution.

    Inequality Based On Hierarchical Clustering Protocol in WSNs
    ZHANG Zhichao
    . 2015, 28(3):  83. 
    Abstract ( 543 )   PDF (711KB) ( 454 )  
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    The inequality of hierarchical clustering (UHC) protocol is proposed for the defect of the radius of nodes in the campaign and cluster heads selection mechanism in the unequal cluster-based routing protocol (EEUC).The network area is divided into layers to reduce the burden of cluster heads and improve the efficient use of energy.Matlab simulation results show that UHC agreement effectively reduces the density of cluster-heads nodes and prolongs the service life of network.

    Research on Routing Protocol for Wireless Sensor Networks Based on AODV
    ZHANG Dehai,HAN Shuaishuai,WANG Baolin
    . 2015, 28(3):  87. 
    Abstract ( 601 )   PDF (700KB) ( 470 )  
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    This paper researches the AODV routing protocol,analyzes the multipath routing protocol,and puts forward an energy efficient multipath AODV routing protocol for wireless multimedia sensor networks.EEMP-AODV builds multipath from source node to destination node.In order to achieve load balancing and extend the entire network lifetime,it takes hop count and nodes' residual energy into account in route choice.EEMP-AODV avoids congestion by divide rate into multipath.Finally,NS2 is used to simulate the proposed routing protocol.The result shows EEMP-AODV routing algorithm has a significant improvement in congestion avoidance,real-time performance,throughput and lifetime.

    IBERT Applied in the Virtex-7's GTX Testing
    YU Xin,LI Yuezhong
    . 2015, 28(3):  91. 
    Abstract ( 541 )   PDF (836KB) ( 738 )  
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    The article uses IBERT (integrated BER tester) testing on GTX (high-speed serial gigabit transceivers) of Xilinx Virtex-7 series,and briefly describes the test principle and test methods.Then,according to a large number of experimental results,we obtain some better and faster methods for finding the best parameters for improving the communication quality,which provides an appropriate testing basis for the design and implementation of subsequent high-speed serial signal transmission between Gigabit Ethernet controller and board based on Xilinx FPGA.It is of guiding significance.

    Design of the Fiber-optical Current Differential Protection Synchronous Interface Based on FPGA
    MA Zewei,WU Jialong,LI Kun
    . 2015, 28(3):  94. 
    Abstract ( 477 )   PDF (984KB) ( 409 )  
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    In order to achieve strict synchronization,accurate and reliable data information exchange of the both ends of the optical fiber differential protection device,this paper proposes the use of FPGA to design optical fiber differential protection synchronous communication interface to achieve flexible software module configuration and improve the communication reliability and stability of the optical longitudinal differential protection device.

    Design of a Memory Controller Based on AHB Bus
    LIU Shaolong
    . 2015, 28(3):  99. 
    Abstract ( 489 )   PDF (983KB) ( 458 )  
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    The paper presents a memory controller IP core based on high-speed bus.It takes full advantage of the protocol of AMBA 2.0 to achieve efficient access to the external RAM and ROM.With the implement of timing transition between bus-end and memory-end,the memory controller realizes the timing optimization for three special operations:instruction fetch,write access and atomic operation,improving the access efficiency for those behaviors.Additionally,this design adopts an asynchronous design method for the whole circuit,which reduces the power of controller under the idle state.This IP is described by VHDL,whose hardcore is implemented with FSM (Finite State Machine),thus forming a reusable soft core.

    Quasi-dynamic Calibration of the Shell Capacitive Electronic Pizeo Guage in Application Environment
    WANG Xinhua
    . 2015, 28(3):  103. 
    Abstract ( 422 )   PDF (1015KB) ( 407 )  
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    According to the characteristics of the shell capacitive electronic pizeo gauge,this paper puts forward a dynamic calibration method in an environment the same as or similar to the working environment.The rationality of the calibration method is expounded.The shell the capacitive electronic pizeo gauge is calibrated using this method.Finally,the method is validated by experiment.The result of the experiment and the error is analyzed.

    Study on Series-series Model of Wireless Power Transmission System Based on Resonance Coupling
    GUO Jiancheng,LI Xinjuan,HU Lixin,HU Yufeng
    . 2015, 28(3):  108. 
    Abstract ( 650 )   PDF (943KB) ( 457 )  
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    Wireless power transmission system via resonance coupling displays its superiority in its low radiation,high efficiency,long transmission distance and directional characteristics by using near-field magnetic transmission.The paper uses a new method to simplify the equivalent circuit to analyze the impact of wireless power transmission system based on the resonance coupling series-series model parameters of distance,frequency and load on the transmission efficiency and power and the inner relation,to deduce the calculation model.Under certain load conditions and the spacing,the optimal working frequency and the efficiency at the maximum power of working frequency is consistent through Matlab simulation.The rule is found the output power to be more sensitive to the operating frequency.A wireless power transmission device based on the resonance coupling is designed.The correctness of theoretical analysis is verified by experiment,to provide a useful reference for studying the power wireless transmission.

    Application of X band 10 kW Klystron Power Amplifier in Deep Space Ground Station
    HOU Manhong,GUO Zhongkai
    . 2015, 28(3):  112. 
    Abstract ( 662 )   PDF (1328KB) ( 473 )  
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    Owing to its high output power,high efficiency,low cost,and stable and reliable performance,the klystron plays an important part in the microwave transmission system.In recent years,the domestic klystron amplifier has made great progress with continuous wave output power increasing from hundreds of watts to ten kilowatts.Using solid state+klystron amplification scheme,a set of X band 10 kW CW klystron power amplifier is designed with an operating bandwidth of 95 MHz.The power amplifier is applied on the Deep Space Ground Station (DSGS),an important part of transmitting system in Deep Space Exploration.This paper describes the X band 10 kW CW klystron amplifier composition,the technical performances and the test results.The test data shows that the X-band 10 kW klystron amplifier is stable and reliable,fully meeting the design requirements.

    Analysis of Evaluation Index of the Performance of Radar Signal Sorting
    ZHANG Wei
    . 2015, 28(3):  117. 
    Abstract ( 622 )   PDF (608KB) ( 761 )  
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    This paper presents the radar signal sorting performance evaluation index.According to the principle of PRI sorting,a performance index model is established.And the impact of the variation in RF target characteristics on radar signal sorting performance is simulated.The results show that in ideal sorting conditions,the correct sorting rate increases while the false sorting rate decreases with rising PRI differences between different types of signals with a definite random noise variance,to which the missing rate is related:the greater the random noise variance,the smaller the missing rate is.

    WCDMA and Wireless Network Controller for Load Analysis and Expansion
    ZHANG Shucai
    . 2015, 28(3):  120. 
    Abstract ( 458 )   PDF (607KB) ( 451 )  
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    With the rapid development of the 3G service,WCDMA network load is also gradually increasing,and the signaling processing and hardware/software configuration of the treatment capacity can not meet the demand of network and the problem of unbalanced WCDMA networks wireless network controller.Based on a Unicom RNC data statistics,an analysis of its load is made,and an expansion scheme for the WCDMA wireless RNC network is proposed,which achieves good results in the company after the trial.

    Effect of the Capacitance on the Transmission Characteristics of Frequency Selective Surface
    JIN Kaitao,LIAO Bin
    . 2015, 28(3):  123. 
    Abstract ( 533 )   PDF (625KB) ( 510 )  
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    Active frequency selective surface (AFSS) is the frequency selective surface (FSS) loaded with active device,such as variable capacitance diode or PIN diode,which can be used to control the FSS performance by means of self-adjustment.Based on the principle of equivalent circuit,the structure of a rectangular slot FSS is designed and the transmission characteristics of frequency selective surface loaded with capacitance are studied in this paper.The simulated results show that the resonance frequency drifts to the low frequency and the transmission bandwidth decreases upon loading capacitance,and the transmission characteristic has a good controllability.

    Design of a Self-adaptable Slope Compensation Circuit for Buck DC-DC Converter
    HE Jun
    . 2015, 28(3):  126. 
    Abstract ( 615 )   PDF (579KB) ( 618 )  
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    A novel slope compensation technique is presented to improve the loading capacity of buck DC/DC converters.To solve problems such as inherent instability of DC/DC converters at large duty cycle and its decreased loading capacity as a result of traditional slope compensation,a piecewise linear slope compensation circuit is designed,which improves both stability and loading capacity of the system.Based on a 0.5 μm CMOS process,the circuit is verified by Cadence simulation.Anticipated results have been achieved.

    Design of Circularly Polarized Magnetic Dipole Antenna
    HUANG Wei,SUN Baohua,SUN Ling,SUN Qiao
    . 2015, 28(3):  129. 
    Abstract ( 594 )   PDF (762KB) ( 479 )  
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    A new circularly polarized (CP) magnetic dipole antenna is designed for operation at the global positioning system (GPS) L2 band.The antenna has the shallow and embedded structure and consists of two pairs of orthogonal magnetic dipoles.The four sides of the antenna are grounded with sheet metals,leading to the antenna's insensitivity to the surrounding environment,forming a closed and firm box.The designed antenna has been fabricated and measured after electromagnetic simulations.The measured results show that the antenna has an impedance bandwidth of 6.5% for S11<-10 dB and a 3-dB axial-ratio bandwidth of about 2.61%.The antenna is suitable for airborne GPS applications.

    A Comprehensive Study of the Encounter-based Low-power Clock Tree
    FENG Wanpeng,WANG Ou,JI Yingjun,SONG Zhipeng
    . 2015, 28(3):  132. 
    Abstract ( 484 )   PDF (712KB) ( 567 )  
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    The clock tree based on Cadence CCOPT engine is designed to reduce the power consumption of the clock tree by the use of gating techniques and the choice a suitable buffer or inverter.The physical design and simulation of dynamic power analysis data indicate that the power consumption of the clock tree to save about 50% under different operating conditions with guarantee of convergence;both buffers and inverters are suitable for the construction of the clock tree,but buffers save 30% the power consumption compared with inverters.

    350 nm AlGaN-based Ultraviolet Light-Emitting-Diode Using p-AlGaN/GaN Superlattice
    WANG Dandan,DING Juan,HAN Mengxu,MENG Xijun
    . 2015, 28(3):  136. 
    Abstract ( 651 )   PDF (631KB) ( 518 )  
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    By using p-AlGaN/GaN SPSLs as the p-layer of LED,the peak wavelength of 350 nm AlGaN based UVLED is grown on the sapphire substrate.The AlGaN/GaN superlattice polarization reduces the Mg acceptor ionization,thus greatly improving the LED devices optical and electrical properties.The devices exhibit an output power of 22.66 mW at the current of 350 mA,corresponding to a low forward voltage of only 3.75 V.It means that the optical power of such LEDs is high enough to be used in practical applications.

    Research of Laser Cladding Repairing Technology of Roller
    SUN Liping,ZOU Xuan,XU Weiming
    . 2015, 28(3):  139. 
    Abstract ( 632 )   PDF (953KB) ( 440 )  
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    In recent years,application of laser surface treatment technology on the roller surface treatment widely,the main object of this paper is roll,research on laser cladding technology used in bar roll surface,and the laser cladding process parameters are explored.For the laser repair roll processing process,it is difficult to control the cladding quality problem,by changing the laser power,scanning speed,powder feed rate parameters of laser cladding method,through experiments the process parameters in laser power 3.7 kW,scanning speed,powder feed rate of 6 mm·s-1 19 g·min-1,the overlapping coefficient in 40%,the best fusion effect of laser cladding,the final tracking operations on roller repairing is well,single groove rolling cladding before the amount is increased nearly 1 times,it creates considerable economic benefits for the enterprise.

    Infrared Touch Screen Base on STM32
    HE Chengjia
    . 2015, 28(3):  142. 
    Abstract ( 845 )   PDF (1060KB) ( 574 )  
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    The infrared screen performs plane coordinates positioning using the good infrared directional characteristics.It obtains the location of touch point by arranging several transmitter-receiver tubes around the screen and by collecting and processing the signals from the receiver tube.The system uses the STM32F103 Cortex-M3 core as the main controller to realize standard USB touch device via protocol of USB HID (Human Interface Device),without the need for manual installation of l the driver for touch screen input,as long as the diameter of touch pen is over 5 mm so as to block the infrared (such as a finger,brush,etc.) Operations like writing,scaling,and rotating can be completed by touch.Installation is simple by connecting the USB interface directly to a PC with good anti-interference ability.

    Laying Angle Determination of Photovoltaic Array Based on Simulated Annealing Algorithm
    XIE Shilong,ZHANG Haibo,ZHANG Chi,GU Weidong
    . 2015, 28(3):  148. 
    Abstract ( 479 )   PDF (676KB) ( 494 )  
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    The laying angle of battery board and solar radiation will affect the working efficiency of the photovoltaic battery in the laying of small building solar system.We used the laying angle of photovoltaic array as decision variable and the maximum value of the total radiation intensity of the inclined plane as the object function to build the nonlinear model.We solved the optimal laying angle based on the simulated annealing algorithm so that we can take advantage of the solar energy fully and make photovoltaic array more efficient.At the same time,the laying of photovoltaic module can save battery occupied area.The method solved the problem of complex nonlinear optimization simply and efficiently.

    Research on Solar Maximum Power Point Tracking Technology
    JIN Wei
    . 2015, 28(3):  150. 
    Abstract ( 646 )   PDF (773KB) ( 501 )  
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    In order to improve the efficiency of the solar LED Lighting system,it is important to detect the solar battery output power in real time and ensure the solar battery always works at the maximum power point.This paper briefly describes the output characteristic of the solar battery and the principles of tracking maximum power point,and analyzes several tracking methods,i.e.the constant voltage algorithm,the perturb-observe algorithm and the conductance increment algorithm.And an improved algorithm that combines the constant voltage algorithm and perturb-observe algorithm is put forward to solve the problems of slow tracking,oscillating phenomenon,etc.by traditional methods.It makes good use of their respective advantages to achieve fast tracking and further improve the utilization efficiency of solar battery.

    Surface Modification of BaTiO3 and Dielectric Properties of Modified BaTiO3/Polyimide Composites
    PAN Zhilong
    . 2015, 28(3):  154. 
    Abstract ( 577 )   PDF (728KB) ( 578 )  
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    The chemical reduction method is used in this paper to deposit copper nano-particles (about 5~20 nm) on the surface of the barium titanate (BT) of a diameter of 100 nm.Then the dielectric properties and the mechanism of modified BaTiO3/polyimide composites are studied.The results show that copper on the surface of the BT nano-particles by chemical bonds,that is,the copper crystal structure is linked with the BT crystal structure.So this composite is a two-phase composite material different from the three-phase composite materials of BT/conductive particles/polyimide.In addition,although some copper nano-particles are oxidized,the conductive performance is reduced,but the modified BT/polyimide composite material also has the properties of the low loss and the high dielectric constant.This fully shows that this new type of two-phase composite material can achieve the goal of high dielectric and low loss.

    Effects of Ag/AgCl Electrode Area on Electrochemical Noise
    ZHANG Xingxing,CAO Quanxi,ZHAO Honggang
    . 2015, 28(3):  158. 
    Abstract ( 403 )   PDF (612KB) ( 380 )  
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    With the electrochemical reaction principle of the electrode as the theoretical basis,the application environment of marine electrode is simulated.Pairs of electrodes with different surface area are then made by powder pressure molding process.The heights of these electrodes were 5 mm,8 mm,11 mm,respectively,with the same diameter 10 mm.The influence of superficial area on electrical noise and stability of electrode is studied.The lowest electrical noise 0.961 nV/ Hz is obtained for the electrode with a height of 11 mm.The investigation shows that the increase of superficial area can improve the stability and reduce the electrical noise of electrode.

    Review of Dynamic Spectrum Access
    XU Di
    . 2015, 28(3):  161. 
    Abstract ( 657 )   PDF (808KB) ( 429 )  
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    Dynamic spectrum access is a new spectrum sharing model that allows secondary users to access the rich spectrum holes in the authorized spectrum bandwidth.DSA technology can alleviate shortage of spectrum problem and improve spectrum efficiency.In this article,we discuss the challenges that DSA faces and point to its direction in the future.Firstly,we give an introduction to the latest spectrum sensing and spectrum sharing.Then we investigate the challenges that prevent DSA from major commercial deployment.We believe that,facing these challenges,a new DSA model is essential,in which it is possible for the authorized users to cooperate in DSA and get more flexible spectrum sharing.


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