Table of Content

15 September 2016 Volume 29 Issue 8

  

Articles

Comparison of Open Loop and Closed Loop Characteristics of the High Voltage Switching Power Supply

JIANG Jing, PAN Linlin, LI Hongda, CHE Long, ZHAO Hongyang , YIN Bo

. 2016, 29(8):  1. 

Abstract ( 508 )   PDF (1525KB) ( 596 )  

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A smallsize lowcost high voltage switching power supply is developed. An output voltage of 30~210 kV can be adjusted and converted at 70 kΩ and a half width of 15 μs. The performance index are verified by matlab/simulink simulation and experiments, and the Pspice simulation is also introduced in view of the difficulty in maintaining the stability of open loop output voltage and the switch electrode of the feedback loop system, thus offering a stable output voltage of 154 kV at a stable time of 20 μs. Computer simulation results show that the high voltage switching power supply with the feedback system has good voltage regulation characteristics.

Investigation and Design of UHF Antimetal Tag Antenna

ZHANG Qiao, ZHOU Yonggang, PENG Jianglu

. 2016, 29(8):  4. 

Abstract ( 382 )   PDF (1349KB) ( 421 )  

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The design of antimetal tag antenna has been a hot spot in RFID research. In this paper, a UHF antimetal RFID tag antenna on ceramic substrate is designed and investigated. The results shows good impedance matching of S11＜-20 dB of the tag antenna at 905~925 MHz, as well as an omnidirectional radiation pattern, which is in agreement with simulation. Besides, the ceramic substrate ensures a high temperature resistance, which implies that the tag can work under tough circumstances while maintaining proper performance.

Design of the Online Growth Monitoring Circuit for Shaking Incubators

CAO Heng, LI Jianjie, WANG Ting, WU Xiao, LIU Li

. 2016, 29(8):  7. 

Abstract ( 359 )   PDF (2125KB) ( 373 )  

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Biological shaking incubator is a common laboratory instrument often used to cultivate microorganisms, bacteria and cells. Traditional incubators fail to provide realtime information on material growth. A circuit of online optical density detection based on turbidity method is designed. The circuit, consisting of the LED controlling circuit, the photoelectric conversion circuit, the amplifier and the A/D sample circuit, realizes the real optical density detection during cultivation. Relative platform has been set up to verify the accuracy and stability of the optical density detection circuit. The error between the optical density value detected by optical density detection circuit and the average one in different states is shown to be less than 3%, indicating that the circuit reflects the optical density value of the cultured materials in real time accurately.

Design and Implementation of the Multi Sensor Integrated Navigation System for MiniUAV

ZHOU Hongkun

. 2016, 29(8):  10. 

Abstract ( 474 )   PDF (1582KB) ( 589 )  

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Accurate and reliable motion states data are essential for control of small unmanned aerial vehicle (UAV). In the actual control, two or even more of sensors are typically required to obtain the motion data by the specific fusion algorithm. In this paper, an integrated navigation system is designed by integrating GPS, inertial attitude reference system (AHRS) and barometric altimeter based on the actual flight control requirements of UAV. Then a multi-sensor data fusion algorithm is realized to estimate the states data of position, velocity, acceleration, and Euler angles. Finally, the validity and usefulness of the designed system are verified in actual flight tests.

Design of Power Display Control Circuit for Portable Powers

CHEN Fei

. 2016, 29(8):  14. 

Abstract ( 400 )   PDF (1331KB) ( 562 )  

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This paper designs a circuit for controlling the power display status when the mobile power is under charging and discharging. In this circuit, the battery voltages dividers and boost modules reference are input into the comparator, combined with the clock signal for logic control. The power display is divided into multiple stages. Power display is achieved with 4 LEDs. In case of anomaly of other modules of the chip, an abnormal state indicator is introduced to remind the users. This circuit uses TSMC0.35 μm process. Cadence simulation in Spectre environment shows that the design achieves the desired effect.

Cascaded Static Var Generator Based on Current Deadbeat Control

LI Dengke, YANG Wenhuan, HOU Tiantian, HUANG Minyao

. 2016, 29(8):  17. 

Abstract ( 425 )   PDF (1693KB) ( 303 )  

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The cascade type converter applied in reactive power compensation unit is an important way to realize the large capacity of reactive power compensation. This paper briefly introduces the basic principles and structure of SVG with emphasis on the method of current deadbeat control and instruction current calculation based on the instantaneous reactive power theory. In this paper, the current deadbeat control instead of PI control is used in the cascaded SVG in view of the difficulty in determining parameters and the complex mathematical model of the PI controller. Finally, Matlab simulation verifies its feasibility.

Dual Bandnotched Ultrawideband Antenna Based on Slots and Parasitic Elements

HAN Tao, WANG Hongcheng

. 2016, 29(8):  21. 

Abstract ( 404 )   PDF (2221KB) ( 385 )  

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A planar monopole UWB antenna with dual band notched characteristic is proposed. The UWB base antenna has a wide impedance matching characteristic with the gradually stepped impedance feeder. By opening slots on the antenna and embedding a pair of rectangular shaped parasitic elements on the ground, the dual bandnotched characteristic can be obtained respectively. The measured results show that the proposed antenna achieved a wide bandwidth of 3~11 GHz with VSWR＜2, stop bands of 3.3~4.0 GHz for WiMAX and 5.0~5.85 GHz for WLAN. Both the simulated and measured results show that the proposed antenna has the advantages of simple structure and good bandnotched function on the stop band, thus a good candidate for various UWB applications.

(Institute of Electronic CAD, Xidian University, Xian 710071, China)

LI Rongrong

. 2016, 29(8):  25. 

Abstract ( 407 )   PDF (1253KB) ( 249 )  

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In this paper, a chargepump phaselocked loop integrated in DCDC chip is designed. The deadzone of phasedetection is eliminated by elongating delay of the reset circuit on the basis of the traditional D flipflop structure. The chargepump adopts the symmetry current structure, which has a good performance in resisting current unbalance and charge injection effect. The frequency divider is programmable. Finally, Cadence simulation which is based on the CMOS technology results of the circuit show that there is a good linear characteristic for a speed locking time, a wide frequency range voltage and a low phase noise. Its performance parameters are: power supply voltage 2.4 V, frequency range of 250～750 kHz, locking time is less than 50μs and the phase jitter is less than 30 ns.

Thermal Control System Design of Electronic Equipment

ZHU Qifan，DUAN Jun，YANG Fanghong

. 2016, 29(8):  28. 

Abstract ( 417 )   PDF (1614KB) ( 446 )  

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To solve the problem of cooling electronic equipment, we take the reliable cooling plan of adding thermal slices and thermal conductive fillers to design a thermal control system for an electronic equipment. The finite element model is built by HyperMesh. By simulation of Patran/Nastran, the result shows the thermal of PCB and components gets lower and more uniform after taking measures for thermal control. It verifies the rationality of the design for thermal control system.

Wireless Broadcasting MIMO Channel Models and Evaluation Methods of the Performance

SUN Yarong, RUI Yun, SU Shengjun

. 2016, 29(8):  31. 

Abstract ( 402 )   PDF (1555KB) ( 253 )  

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ATSC obtained two broadcasting network MIMO channel models based on mobile and fixed scenarios, with in consideration such factors as the intrarelation, Doppler frequency shift, and Lay factors. But the two channel models have not unified evaluation methods for further study and optimization about MIMO broadcasting network technology. This paper respectively simulates the two channel models presented by ATSC3.0 and provides corresponding evaluation methods, which are then adopted to evaluate the two scenarios of the channel model. For the Helsink2 channel Model based on mobile scenario, a length of time varying channel is selected as a period to evaluate its throughput. For the MGM channel model based on fixed scenario, 50 channels are tested and its range of SNR confirmed to evaluate performance. The evaluation methods and simulation of the two MIMO channel models will play an important role in the further study and optimization.

Design of a Multichannel Kuband Transceiver

XU Senfeng，WU Liangliang

. 2016, 29(8):  36. 

Abstract ( 475 )   PDF (1085KB) ( 444 )  

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The fundamental working principle of a Kuband transceiver which consists of four receiving channels and one transmitting channel is introduced first, and then a detailed analysis is made of the unit circuits and key technology. The test results show that in the working bandwidth of 2 GHz and at -55～+85 ℃, the output power of transmitting channel is up to 31±1 dBm, the gain flatness in band is≤±0.5 dB, the switch isolation is≥90 dB, and the gain of receiving channel is up to 30±1 dB, the noise figure is≤5 dB, and the channel isolation is≥60 dB. The test results demonstrate that the design is valid and meets the requirement.

Circuit Design of the Audio and Video Acquisition System

DENG Xutong, CHEN Jianchun

. 2016, 29(8):  39. 

Abstract ( 329 )   PDF (1590KB) ( 597 )  

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A design of the audio and video acquisition system circuit is proposed to meet the increasing demand for video image sharpness. The circuit is capable of audio and video signal acquisition with underlying hardware of variable parameters. The peripheral interface enables communication between the computer and the Internet. The experimental results show that the designed circuit offers good stability and is of value in practical engineering.

Estimations of TDOA and AOA Based on Microwave Photonic Technology

CHANG Chao

. 2016, 29(8):  43. 

Abstract ( 334 )   PDF (1218KB) ( 532 )  

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A new method based on optical power measurement is proposed for estimating the microwaves parameters with flexibility. The method adopts two MachZehnder Modulators to obtain the optical powers of two microwaves at the output terminal, thus the phase difference between them. Then we can obtain TDOA and AOA by calculation. Simulation of the model shows the method is effective and of high accuracy.

Fast Direction Finding Technology for Antiradiation Seeker Based on Digital Beam Forming

LI Xiang, RAO Xian

. 2016, 29(8):  46. 

Abstract ( 451 )   PDF (1626KB) ( 240 )  

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A fast direction finding technology based on digital beam forming is proposed for the angle searching of antiradiation seekers. The problem of angle searching is converted into the binary angles searching in space using digital beam with different widths. The basic principles, the speed and the amount of computation of this method are studied. The simulation results show that the searing time casting and efficiency are improved by the proposed method while keeping the same angle measurement accuracy and resolution.

Current Stress and Efficiency Analysis of the  Quadratic Buck Converter in CCM

FENG Jinzhi，LI Zenghui

. 2016, 29(8):  51. 

Abstract ( 413 )   PDF (1222KB) ( 249 )  

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The quadratic converters realize the cascade of two converters to achieve wide voltage conversion ratios and higher efficiency, compared with the conventional converter, the power losses increase accompany with the amounts of the components. In this paper current stress and conduction loss for every component in the circuit will be derived considering internal resistances to analyze the detailed converter power losses. The work efficiency of the converter and relationship among circuit parameters will also be studied. Simulation results are presented to verify the theoretical analysis.

Research on the Equal Error Protection of the Interleaver in the Turbo Code

YAN Jilei, ZENG Hai

. 2016, 29(8):  55. 

Abstract ( 371 )   PDF (1420KB) ( 243 )  

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The Turbo code is a high performance channel coding mechanism, which has a near Shannon limit error correction capability. In this paper, the design rules of the interleaver are analyzed and the equal error protection of the Turbo coding is introduced. Then, for the block interleaver, an information input scheme is proposed that writes along the main diagonal of the interleaving matrix; for the srandom interleaver, an additional constraint is provided when randomly generating the index address. Finally, two interleavers with equal error protection capability are obtained. Simulation results show that these modified interleavers can significantly improve the bit error rate of the Turbo code.

Timefrequency Analysis in Radar Signal Recognition

YANG Hongfei, HE Zhengri

. 2016, 29(8):  58. 

Abstract ( 425 )   PDF (1344KB) ( 540 )  

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The application of frequency analysis in signal recognition for sorting radar signal is discussed. This method offers better efficiency in the analysis of nonstationary signals than other radar signal recognition method. Signal feature extraction by the shorttime Fourier analysis (STFT) transformation and the WignerVille Distribution (WVD) is studied respectively and compared by simulation, which shows that STFT can analyze partial frequency domain characteristics of the signal, while at the same SNR, WVD enjoys a smaller noise ratio and a higher degree of polymerization, hence better reflecting the relationship between time and frequency; both methods are able to distinguish the characteristics of modulated signals.

Motor Noise Test Based on SeeSV Acoustic Source Location

YU Huijie, XU Qiang

. 2016, 29(8):  61. 

Abstract ( 383 )   PDF (1346KB) ( 313 )  

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A test method combining the acoustic camera SeeSV with microphones to detect the motor vibration signal simultaneously is proposed for measuring a drive motor sound pressure level and noise frequency. Different SeeSV frequency bands are chosen to locate and identify the noise source, and isolate motor noise spectrum. Microphones are used to measure the motor noise intensity, which is verified by vibrating signal. The result shows that noise frequency and sound pressure level from drive-motors can be identified in complex noises by using the combination of SeeSV with sound transmission meter in practical engineer noise evaluation. The noise frequency and sound pressure level is 266625 Hz and 607 dB, respectively.

Dynamic Modeling and Simulation Analysis of Thermal Deformation of Linear Motors

FAN Zhenhua, LIN Xiankun

. 2016, 29(8):  64. 

Abstract ( 459 )   PDF (1463KB) ( 404 )  

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The modeling and simulation of thermal deformation of the linear motor are studied to improve the motion precision of the uniaxial linear motor. The factors that influence the uniaxial linear motor thermal deformation are analyzed, and the onedimensional dynamic heat transfer mathematical model is constructed. The heat transfer characteristics of linear motor mechanism are analyzed by using ANSYS. And then, onedimensional mathematical model for thermal deformation is established. Finally, the thermal deformation data varying with time is calculated based on simulation data. This paper provides not only the method for uniaxial linear motor thermal deformation modeling, but also the heat transfer characteristics of the linear motor.

Parameters for the Lifetime Estimating Model by EM Algorithm

HAO Yumei

. 2016, 29(8):  68. 

Abstract ( 360 )   PDF (1019KB) ( 445 )  

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A new EM algorithm is proposed to estimate the complexity and the computational complexity of the unknown parameters in the lifetime model. Firstly, the related life model is introduced, and the unknown parameters of the lifetime of the EM are estimated by using the expectation maximization algorithm (EM). Finally, the prediction results are compared with the results of the different time periods.

Research on PID Parameters Based on NSGAII in a Combination of Different Indicators

WANG Zhihao

. 2016, 29(8):  70. 

Abstract ( 531 )   PDF (1257KB) ( 381 )  

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The PID parameter optimization based on multiobjective evolutionary algorithm is proposed by analyzing performance metrics to compare different combinations. The method is based on the nondominated sorting genetic algorithm II (NSGAII) for generating different targets after the introduction of different indicators combination of properties function. Analysis and comparison the curves of step response output is made through Matlab simulation of the control system to find the optimal combination of the performance indicators IAE, ISE and squared term control input.

A Spectral Clustering Algorithm Based on Average Density

LI Gen, WANG Yagang, ZHOU Xiaowei

. 2016, 29(8):  74. 

Abstract ( 381 )   PDF (2130KB) ( 305 )  

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Choosing the scale parameter of gauss kernel function irregularly has a serious effect on clustering results when using traditional spectral clustering algorithm to construct similarity matrix. A spectral clustering algorithm based on average density is proposed, which uses K average neighbourhood distance as the scale parameter and introduces the local data density information, making clustering results in conformity with the practical data distribution. The adaptation of the similarity matrix to different local densities also makes the algorithm relatively insensitive to the spatial distribution of datasets. Experimental results on both different datasets show the effectiveness and good robustness of this proposed algorithm.

Mining Maximal Frequent Itemsets Based on Back Track

ZHANG Xinjing, YU Jiawei, WANG Hongmei

. 2016, 29(8):  78. 

Abstract ( 382 )   PDF (1287KB) ( 509 )  

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In view of the fact that Apriori algorithms scans the database multiple times and the FP-tree algorithms requires build a large number of conditional trees, the GBMFI algorithm is proposed for mining maximal frequent itemsets. The transaction database is stored in vertical format. Based on the enumeration tree, the GBMFI algorithm performs the pruning operation to narrow the search space with the properties of nonfrequent subsets and the support information of the node to get maximal frequent item sets. Experiments demonstrate the effectiveness of the GBMFI, especially for spares data sets.

Modal Analysis of Worm Gear Transmission Performance by the Finite Element Method

YANG Yongming

. 2016, 29(8):  82. 

Abstract ( 575 )   PDF (1904KB) ( 400 )  

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A modal analysis of worm gear transmission performance based on finite element method is proposed to reduce the vibration deformation caused by dynamic load in a worm gear transmission system for longer service life. The ANSYS Workbench is used for modal analysis of worm gear transmission performance to extract the free vibration natural frequencies and vibration types. Experimental results show that a reasonable modal analysis of worm gear transmission performance and the extraction of rational parameters of are of great importance to the reliability of the worm gear.

Applications of ADAMS in the Analysis and Optimization of the Stability of the Steel Coil Car

CHEN Yiyi, LI Haolin, ZHA Degen

. 2016, 29(8):  85. 

Abstract ( 353 )   PDF (1696KB) ( 277 )  

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Stability of steel coil car is an important factor during transporting steel coil. A dynamic and kinematic analysis of the scissors steel coil car is made using ADAMS, finding that the steel coil car has an impact on lifting up and down. The structure is optimized based on structural analysis by SolidWorks modeling, and the stability of the structure is verified by ADMAS. The results show a significant reduction of the shock generated during steel coil car lifting with its stability significantly increased.

Research on Mouth Type Classification Algorithm Based on BP Neural Network

WEI Shuang

. 2016, 29(8):  89. 

Abstract ( 412 )   PDF (1696KB) ( 397 )  

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Aiming at traditional mouth type classification mainly depends the observation of doctor, which is easily influenced by subjective factors and cant be quantified, This paper proposes a kind of mouth type classification algorithm. On the basis of ASM, the algorithm extracts the mouth template, constructs the feature vector with a series of rotation, binarization and heavy sampling, and then using BP neural network training feature vector to complete the mouth type classification. Experimental results show that the proposed algorithm can achieve accurate classification of mouth, which has a certain reference value for clinical medical treatment.

A Modified PSO Combined KMeans Clustering Algorithm for Image Segmentation

WU Chunxue, LIU Xunyang

. 2016, 29(8):  92. 

Abstract ( 399 )   PDF (1448KB) ( 455 )  

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The heavy dependence of the Kmeans clustering classification on selecting of the initial centers makes it easy to fall into local optimum. A RWPSOKM based on random weight particle swarm algorithm and Kmeans algorithm is proposed. The global search capability of random weight particle swarm optimization algorithm is used first to avoid falling into local optimum, after which the population diversity is calculated according to the formula to execute Kmeans algorithm, and the local search of Kmeans algorithm is employed to achieve fast convergence. Experimental results show that RWPSOKM is superior to Kmeans clustering and PSOK in segmentation effect and efficiency.

Sizing Optimization Strategy for Machine Tool Bed Structure Based on OptiStruct

ZHOU Hao, DING Xiaohong, ZHANG Heng

. 2016, 29(8):  96. 

Abstract ( 380 )   PDF (2074KB) ( 233 )  

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A typical bed structure of a cylindrical grinding machine is studied as an example in lightweight design, and a strategy divided into layers of sizing optimization is put forward. The pad iron layout is optimized as the first layer with OptiStruct with the second layer based on sensitivity analysis to optimize the size of bed structure. The optimized results show that the first natural frequency increases by 5.74% and the weight decreases by 7.15%, indicating that the strategy of sizing optimization is feasible and effective.

A method of Coupling Polarity Discrimination Based on Field Distribution of the Filter

LI Gang，HU Xu

. 2016, 29(8):  100. 

Abstract ( 391 )   PDF (1389KB) ( 480 )  

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The coupling between the resonant cavity is an important parameter to determine the number and position of the filter zeros. In the process of determing the coupling polarity, we need to simulate the eigen mode multiple times in the perfect electric and magnetic boundary conditions. The steps are complex and time consuming.The paper presents a fast identification method to distinguish the coupling type in the design of the filter .In this method, the coupled cavity is characterized by a full wave simulation of the eigen mode and the coupling type of the cavity can be quickly judged from the field distribution of the lowest intrinsic resonance frequency. At last, the example of a complex coupling type is analyzed and the results are compared with the traditional method. The results show that the method has good accuracy and has a good practical value.

Computer Image Denoising Algorithm Based on Wavelet Decomposition

ZHANG Yang

. 2016, 29(8):  103. 

Abstract ( 368 )   PDF (1286KB) ( 385 )  

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Noises arise in the formation computer images due to the interference of external factors, greatly affecting the quality of image. The image denoising can be achieved by wavelet decomposition which meticulously divides the image signals in the frequency domain and selects the appropriate threshold. This paper discusses the quality of the image, wavelet decomposition, Mallat algorithm, and the wavelet threshold denoising. The wavelet decomposition of image signal denoising is performed by Matlab simulation. The simulation results show good image denoising effect.

Research and Analysis on the Implicit Diversification Ranking Method for Information Retrieval

WU Yanyan，ZHOU Xinke

. 2016, 29(8):  106. 

Abstract ( 387 )   PDF (1404KB) ( 471 )  

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Research on implicit diversification algorithm for information retrieval. On this basis, the documents are diversified. In this paper, first we introduce the maximum marginal relevance (MMR) method, Kullback-Leibler divergence (KL) method and modern portfolio theory (MPT), then use these three methods to re-rank data sets, and then evaluate and compare the performance of the three methods. Finally, it is concluded that the implicit diversification methods can improve the performance compare with the original results when the correlation and diversity in a certain percentage of linear combination .

Ambient Temperature Fluctuations Grinder Geometric Precision of Uprights

LIU Chao，LI Haolin

. 2016, 29(8):  110. 

Abstract ( 348 )   PDF (2400KB) ( 301 )  

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Based on environment temperature fluctuations caused by the thermal error of machine tool, a grinding machine in laboratory columns as the research object, using the finite element analysis under different environmental temperature fluctuation of the grinding temperature field and thermal deformation of the post has carried on the simulation analysis, then get the environmental temperature fluctuation amplitude and frequency of the influence law of the geometric accuracy. The research results show that when the environment temperature fluctuation amplitude for 2 ℃, fluctuation cycle2/3 hour, thermal error is less than 1 μm on the column guide rail vertical degree, straightness thermal error is less than 05 μm. In guarantee the machining accuracy of grinding machine can also greatly reduce the difficulty of the temperature control of the workshop, and save energy.

Offline Interferometer Defuzzification

TIAN Bing

. 2016, 29(8):  114. 

Abstract ( 426 )   PDF (1072KB) ( 483 )  

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A comparison is made between two commonly used defuzzification methods (baseline length and statistical phase variance) for linear interferometer DF where blur may result from cyclical phase ambiguity. Theoretical analysis and simulation are performed at different SNRs and short baseline spacings. The results show that at a low SNR the statistical phase variance method offers better defuzzification accuracy and stability, and signal adaptability than the baseline phase variance method; the change in short distance has great impact on the measurement errors by the statistical phase variance method.

Virtual Machine Cluster Optimization Based on Migration in Cloud Environment

JI Lili, LI Ye

. 2016, 29(8):  117. 

Abstract ( 369 )   PDF (1508KB) ( 392 )  

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An optimization algorithm based on virtual machine migration is proposed for the load imbalance in virtual machine clusters. The algorithm uses the prediction mechanism to eliminate unnecessary virtual machine migration caused by temporary crossborder of host resource utilization. It dynamically adjusts the weights of various resources through realtime monitoring of the load of the nodes. It can select the virtual machine which will reduce the maximum degree of the host load to migrate according to the weight of the resources. In selecting the target node, it combines the multiobjective decision method with the multi resource matching rate, SLA (service level agreement) violation rate and other management objectives. Experimental results shows that the algorithm proposed enjoys smaller number of migration and lower rate of SLA violation in the premise of load balancing than other load balancing algorithms of the same type.

Remote Sensing Image Fusion Algorithm Based on Guided Filtering

NA Yan, REN Mengqiao

. 2016, 29(8):  121. 

Abstract ( 408 )   PDF (1317KB) ( 453 )  

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A guided filteringbased remote sensing images fusion algorithm is presented in this paper. Weighted coefficients are determined with guided filter, wavelet coefficients and approximation coefficients are fused by the weighted fusion method. A fused image is obtained by inverse wavelet transform. Experiment results show that the fused image based on the proposed algorithm contains a great amount of information with clear details.

Research on the MultiPath Routing Protocol in the Wireless Mesh Network

JIA Xiaohui, LIU Naian, LI Xiaohui, SHI Peng

. 2016, 29(8):  124. 

Abstract ( 364 )   PDF (1050KB) ( 248 )  

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The L2MPM (Layer 2 Mesh Protocol for Mobile) routing protocol works on the second layer which belongs to the backup route in the multipath routing, but it does not consider the link intersecting between main and backup path to reduce the tolerance of the network. An LDL2MPM (LINK_DISJOINT_L2MPM) routing protocol based on L2MPM is proposed in the paper, which adopts the strategy of nonintersecting link that adds the first hop and the last hop to the packet of Hello to ensure that the two paths selected by the protocol are linkdisjoint．The simulation results show that the rate of packet delivery increases by about 6%, and the average endtoend delay reduces by about 5% compared with those of the original routing protocol.

Indoor Environmental Quality Monitoring System Based on MultiSensors

SUN Jinxiang, CAO Yinjie

. 2016, 29(8):  127. 

Abstract ( 410 )   PDF (1325KB) ( 621 )  

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An indoor environmental quality monitoring system based on multisensor data fusion is proposed for the acquisition of indoor formaldehyde concentration, temperature, humidity, PM1.0, PM2.5, PM10, and CO concentration, which are transferred to a computer monitor through the RS485 communication. C # interface displays realtime data and integrated environmental quality with voice alert at the exceeding of the upper limit. The data is stored in the SQL database. The test shows that this system is capable of stable, efficient monitoring of indoor environmental data.

A New Modified Anisotropic Diffusion Equations

LIU Biao

. 2016, 29(8):  130. 

Abstract ( 354 )   PDF (1252KB) ( 342 )  

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The anisotropic diffusion equation is a classical image denoising method, but this method can cause a certain degree of fuzzy edge in the process of removing noise. This paper presents a based on improved anisotropic diffusion equation for image to denoising method, through in the objective function of the energy functional add residuals and make the energy functional minimizer is closer to the original function can get better denoising effect. The method can be regarded as the combination of the anisotropic diffusion equation and the total variation model. Experiments show that the new equation has better boundary treatment effect and higher signal to noise ratio than the classical equation.

Performance Assessment of Thermal Power Unit Steam Temperature Control System

HONG Jinsheng，WANG Yagang，LI Xiaofeng

. 2016, 29(8):  133. 

Abstract ( 400 )   PDF (1408KB) ( 370 )  

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Control of steam temperature play an important role in improving lifetime and efficiency of power units.It is very important to keep the efficient and economic of steam temperature control loop. Traditionally it very difficult to get the control system time delay when use minimum variance method. So instead of minimum variance assessment method, the extended horizon performance method is widely used in industry environment. This method has been applied to steam temperature controllers for 300~660 MW fossilfuel control system in ZhanJiang Power Grid.The assessment results show that control performance index has improve 7.8% after improve control strategies.The assessment results of ZhanJiang Power Grid show that the extended horizon performance method is a good way to evaluate the steam temperature control loop of thermal power unit.

The Technology of Multiple Features Handwritten Chinese Character Recognition Based on SVM

ZHOU Qingshu，CHEN Jinjie，JI Pengfei

. 2016, 29(8):  136. 

Abstract ( 404 )   PDF (1275KB) ( 323 )  

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To solve the recognition rate of traditional template matching method is not high for Chinese character, a new method of multiple featureshandwritten Chinese character recognition based on SVM is proposed. In addition to the extraction grid features, also extract the centroid feature, stroke feature, feature point, and use SVM algorithmconstructclassifierto achieve the recognition of handwritten Chinese characters. Experimental results show that the average recognition rate of the proposed method is 95.9% higher than that of the traditional template matching method.

Preparation and Photocatalytic Properties of GaN Nanowires

LI Jia , JIANG Tao , CHENG Hongbin , ZHENG Xuejun , WANG Xianying , WU Dongxu

. 2016, 29(8):  140. 

Abstract ( 395 )   PDF (2241KB) ( 239 )  

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A large number of GaN nanowires are synthesized by the chemical vapor deposition (CVD) method. The morphology, microstructure, composition and optical properties of samples are characterized by field emission scanning electron microscope (SEM), XRay diffraction (XRD), energy dispersive spectrometer (EDS) and Photoluminescence (PL), and the photocatalytic activity of GaN nanowires as photocatalyst is tested via the degradation of rhodamine B aqueous solution under the UVlight. The results show that high quality GaN nanowires fabricated by chemical vapor deposition and GaN as a catalyst have a certain photocatalytic effect. On the one hand, the dye sensitization effect will degrade Rhodamine B aqueous solution; on the other hand, it takes 10 minutes more to achieve the degradation level without catalyst than with GaN as the catalyst. This shows that GaN plays a role in the photocatalytic effect and a small amount of GaN significantly increases its photocatalytic effect. The photodegradation rate constant k of GaN is 0.068 min1, 17.2% higher in efficiency than that with no photocatalyst.

Comparison of MPPT Control Methods Based on GABPNN and Perturb & Observe Algorithm

JIN Yanfei, ZHANG Huilin, ZHANG Song, SHI Chaoran, LI Rongwei

. 2016, 29(8):  145. 

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This paper introduces a modified constant pressure PV MPPT control algorithm based on GABPNN for better power point tracking effect than traditional control method under complex weather conditions. The simulation model of a modified constant pressure PV MPPT control algorithm based on GABPNN is constructed and compared with the P&O control method. The result shows that the algorithm can track maximum power point accurately and quickly with better stability and higher precision.