2005 Vol.23

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

The Research of Stratospheric Balloon Positioning by the Loran-C Augmented Beidou System DUAN Fang, LIU Jian-ye, LIN Xue-yuan Journal of Applied Sciences    2005, 23 (1): 1-5.   Abstract （363）      PDF（pc） （221KB）（99）       Knowledge map    Save A stratospheric balloon positioning method using the Loran-C augmented Beidou system is proposed. The systems working principle is elucidated and the positioning algorithm of searching for the shortest distance between two curves is given.The algorithm was simulated using Matlab software, and it's real-time performance and position error are analyzed.The result shows that the algorithm has good real-time performance and that positioning precision is more sensitive to Loran-C measurement error than to double-star measurement error.It is found that when the Loran-C error and double-star error grow simultaneously, the position error may be equivalent to or even smaller than the error caused only by Loran-C error alone.The positioning precision has a relationship with the choosing of Loran-C chain.The algorithm is also suitable for the positioning of other air/ground/sea vehicle. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Practical Metrics for Z Specifications WU Fang-jun, YI Tong Journal of Applied Sciences    2005, 23 (1): 6-11.   Abstract （302）      PDF（pc） （278KB）（75）       Knowledge map    Save The cost of correcting or remedying errors would increase by geometric series at the later of software development.Thus the quality of formal specifications becomes one of the key issues and difficulties.But little work has been done on how to measure the quality of formal specifications till now.To solve these problems, a suite of metrics to measure schemas of formal specification language Z is proposed.The metrics consider schema decoration, schema inclusion, schema type, and schema calculus.According to these metrics, some problems can be found and further overcome at the early life cycle, which reduce cost greatly.Besides, an effective estimation of the system can be made. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

Nonlinear Exponential Reduced-Order Observers Based on Differential Riccati Equation ZHU Fang-lai Journal of Applied Sciences    2005, 23 (1): 12-15.   Abstract （387）      PDF（pc） （180KB）（97）       Knowledge map    Save The problems of observer design for nonlinear systems with linear output are discussed in this paper. Under the assumption that a differential Riccati equation is solvable, an exponential reduced-order observer is developed by means of coordinate transformation and the gain matrix of the proposed observer depends on the solution of the differential equation.The simulation results show that the performance of the proposed reducedorder observer is good. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

The Surface Model Based Intelligentized Plastic Injection Molding Simulation LI De-qun, ZHOU Hua-min Journal of Applied Sciences    2005, 23 (1): 16-19.   Abstract （316）      PDF（pc） （199KB）（117）       Knowledge map    Save There are two great improvements in the development of injection molding simulation:(1) The surface model based simulation.By using the surface model to replace the conventional mid-plane model, the bottleneck of traditional CAE softwares is broken through;(2) The knowledge-based simulation.By taking full advantages of artificial intelligence and expert system technologies in the CAE system, the initialization, evaluation and optimization of designs can be accomplished with the guidance of CAE.This greatly improves the utility and efficiency of CAE. Related Articles | Metrics | Comments（0） Cited: Baidu(10)

Select

The Statistical Characteristics of the Instantaneous Polarization Projection of Partially Polarized Waves WANG Xue-song, DENG Yong, LI Yong-zhen, DAI Da-hai Journal of Applied Sciences    2005, 23 (1): 20-25.   Abstract （335）      PDF（pc） （266KB）（85）       Knowledge map    Save The statistical characteristics of the instantaneous polarization projections (IPP) of partially polarized waves are studied on the basis of the theory of instantaneous polarization.A novel concept of the distance between an IPP and an expected polarization track is presented.It is essentially a measure of the distance between two polarization signals' IPPs in the metric space.Under the normal hypothesis, the probability density function (PDF) of this distance is derived.It's also proved that this distance obeys the normal distribution approximately when the number of the samples of a partially polarized wave is large enough. These results are of great importance to polarization signal detection, estimation and filtering. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

A Symbolic Dynamics Based Method for Noise Reduction in Chaotic Sequence LI Hui, XU Pei-xia Journal of Applied Sciences    2005, 23 (1): 26-30.   Abstract （299）      PDF（pc） （234KB）（53）       Knowledge map    Save Based on symbolic dynamics, a method for noise reduction of unimodal map chaotic sequence is presented.The Markov process model of symbolic dynamics is discussed and from this model a maximumlikehood method based on the Viterbi algorithm for the noise reduction is derived.And by using symbolic dynamics, the performance of this noise reduction method is analyzed.It is shown that the analysis agrees with the simulation result.The method and its analysis can be applied in noise reduction of chaotic communication. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

A Robust Scheme for Contour Extracting and Tracking YANG Xiao-hui, LI Zhong-ke, WU Le-nan Journal of Applied Sciences    2005, 23 (1): 31-36.   Abstract （271）      PDF（pc） （306KB）（92）       Knowledge map    Save A new scheme is proposed to extract and track the object contour automatically in this paper, it combines the active contour based on the gradient vector flow(GVF-Snakes) and the genetic algorithm (GA) based on the fine-grained model.On the one hand, the GVF-Snakes is improved by using the edge criterion instead of the complex energy computation to reduce its complexity and speed up its search.On the other hand, the selection of the array of the reference points by the GA enhances the extracting performance of the extreme concave contours and noise-disturbing contours.Experiment on the synthetic and natural images demonstrate its robustness and accuracy. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

The Dispersion Characteristics of EBG Structure Consisting of Uniaxial-Chiral Medium ZHENG Long-gen, ZHANG Wen-xun Journal of Applied Sciences    2005, 23 (1): 37-40.   Abstract （323）      PDF（pc） （208KB）（64）       Knowledge map    Save A general model for analyzing the electromagnetic band gap (EBG) structure with bi-anisotropic medium is established by using the plane wave expansion method.An EBG structure consisting of triangular la ttice of air cylinders embeded in a uniaxial chiral medium is simulated.The results show that, when the dielectric constants in the cross section remain the same, an EBG structure with a uniaxialized chiral host (permittivity is positive uniaxial, others are isotropic) possesses a wider complete band gap than the one with an isotropic chiral host.This discovery provides an alternative option for the potential electromagnetic application of the EBG structure. Related Articles | Metrics | Comments（0）

Select

Contour Extraction for Medical Images Based on the Combination of the Statistical Method and Active Contour Models CHEN Zeng-sheng, ZHOU Kang-yuan, LI Chuan-fu, HU Yao-hui, HUANG Dan, WANG Qing-lin Journal of Applied Sciences    2005, 23 (1): 41-44.   Abstract （372）      PDF（pc） （192KB）（110）       Knowledge map    Save The paper proposes a method of images contour extraction which combines the statistical method and active contour models(ACM).To choose the contour points of points distribution models automatically, the minimum description length was chosen as the object function.A typical contour model is obtained from an image training set.After the initialization of a new image's ACM contour, the typical contour mentioned above is used as the deformation constraint to extract the nearly optimum contour.The experiments with the real images show the effectiveness of this method in comparison with the traditional active contour models method. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

A Rapid Acquisition Method of UWB Wireless Communication XU Chi, YIN Hua-rui, XU Pei-xia Journal of Applied Sciences    2005, 23 (1): 45-50.   Abstract （294）      PDF（pc） （265KB）（102）       Knowledge map    Save The UWB signal acquisition circuit based on the analog PLL is improved.A method to obtain the signal clock is studied, and then on the base of this circuit a binary search algorithm is proposed to obtain the pulse position and the timing of the signal frame.The circuit of this method can be realized easily.The simulation results and analysis indicate that it has the merits of precise timing and fast acquisition.It is of considerable reference value for the realization of UWB communication. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

Select

A Research on the Algorithm of the Vehicular Short-Wave Single-Channel Direction Finding System WANG Xiao-dong, DAI Xu-chu, XU Pei-xia Journal of Applied Sciences    2005, 23 (1): 51-55.   Abstract （315）      PDF（pc） （206KB）（59）       Knowledge map    Save Using the traditional algorithm, the vehicular short-wave single-channel direction finding devices can not cope with the single side band signals satisfactorily.This article discusses the vehicular short-wave single-channel direction finding system and gives a new direction finding algorithm based on signal spectrum correlation, to improve the system's performance to when coping with single side band signals. Related Articles | Metrics | Comments（0）

Select

The Adaptive WMSA Channel Estimation Based on Doppler Shift Estimation HUA Jing-yu, SHENG Bin, MENG Qing-min, YOU Xiao-hu Journal of Applied Sciences    2005, 23 (1): 56-60.   Abstract （302）      PDF（pc） （259KB）（66）       Knowledge map    Save The classical channel estimation method is linear interpolation, and the variation rate of the channel corresponds to its maximum Doppler shift.Hence, the interpolation length can be decided by the estimated Doppler shift.An adaptive weighted multi-slot average channel estimation method is thus proposed to improve channel estimation accuracy. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

A Partial Scan Algorithm for BIST Based on Structure Analysis and Testability Analysis XIE Yong-ming, LI Rui, YANG Jun Journal of Applied Sciences    2005, 23 (1): 61-66.   Abstract （314）      PDF（pc） （256KB）（70）       Knowledge map    Save A partial scan algorithm for BIST, which combines the structure analysis and testability analysis, is presented in this paper.The basic principle and implementation of the algorithm are analyzed in detail.The fault simulation experiments on ISCAS89 benchmark circuits by means of this algorithm are made, and the results are compared with the full scan algorithm and the partial scan algorithm based only on the structure analysis.Compared with the full scan algorithm and the partial scan algorithm based only on the structure analysis, our partial scan algorithm can greatly reduce the test time with very close or even greater faults coverage and mess area than the full scan algorithm. Related Articles | Metrics | Comments（0）

Select

The Security Analysis for WLAN TKIP Protocol SONG Yu-bo, HU Ai-qun, CAI Tian-you Journal of Applied Sciences    2005, 23 (1): 67-70.   Abstract （360）      PDF（pc） （179KB）（78）       Knowledge map    Save As an expansion of LAN, the WLAN reduces the cost of building a network infrastructure and enables the users to enjoy the mobile services.The 802.11 standard includes a wired equivalent privacy (WEP) protocol, which is used to protect communications from eaves dropping.Several serious security flaws in this protocol have been discovered.To cope with this problem, IEEE802.11i Group proposed adapting TKIP protocol to enhance the WLAN security.In this paper, through analyzing TKIP protocol, concrete security analyses of TKIP protocol are made.It was shown that although TKIP did indeed increase security and result in significant, provable security gains, but it still failed to meet the need of users in a WLAN environment. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Clustering XML Documents Based on a Structural Summary Tree LIANG Zuo-peng, WU Wen-ming, DONG Yi-sheng Journal of Applied Sciences    2005, 23 (1): 71-74.   Abstract （320）      PDF（pc） （188KB）（62）       Knowledge map    Save An approach for calculating the structural similarity between XML documents is proposed in this paper.The structural information of an XML document is captured with a structural summary tree (SST).By encoding elements as digital numbers, a SST is transformed to a digit-labeled tree.Digital numbers at different tree levels are concatenated to form a vector after the normalization process.Consequently, each XML document is represented as an m-dimension vector.The GA-based clustering algorithm is adopted since it is able to provide good results irrespective of the starting configuration.Experimental results show the effectiveness and scalability of the approach. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

The GenExtractor: A Web-Based Bioinformation Mining System XIN Jian, LU Wei, ZHU Jing-de, WANG Yi-fei Journal of Applied Sciences    2005, 23 (1): 75-81.   Abstract （313）      PDF（pc） （297KB）（93）       Knowledge map    Save GenExtractor is a new Web-based bioinformaition mining system.It can be employed to search for genes with specialized function in the designated chromosome region by mining biology sequence data and gene express data in the online biology databases through the Internet.The molecular biologists can apply this system to identify the candidate genes and gather the relevant information.The actual effect of this system has been validated by screening the Human DNA repair genes. Related Articles | Metrics | Comments（0）

Select

The Analysis and Experiment of Determining the Stable Zone in a Magnetically Fluidized Bed WANG Ying-hui, GUI Ke-ting, SHI Ming-heng Journal of Applied Sciences    2005, 23 (1): 82-85.   Abstract （302）      PDF（pc） （195KB）（87）       Knowledge map    Save Basing on the analysis of the forces on magnetic particles, applying the basic theory of the fluidized bed and analyzing by the dimensionless method, the paper shows that the stable zone in a magnetically fluidized bed mainly depends on Re, Ar, and Er, which are primary factors to show the fludized characteristics of the magnetically fluidized bed.A relationship to express the ratio of minimun bubbling velocity to initial fluidized velocity is obtained through the processing of experimental data.Compared with the results reported before, the relationship proves to be correct on the condition of moderate intensity of the magnetic field, and the error of all experimental and calculated data is less than 8%. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

An Analysis of the Runoff Change Law Based on the Maximum Entropy Spectrum ZHAO Xue-hua, HUANG Qiang, WANG Yi-min Journal of Applied Sciences    2005, 23 (1): 86-89.   Abstract （310）      PDF（pc） （185KB）（70）       Knowledge map    Save This paper discusses the maximum entropy spectrum analysis of runoff time series, compares it with traditional spectrum analysis, and presents the high-resolution character of the maximum entropy spectrum and the prospect of its application in hydrology.The analysis and calculation of the annual runoff time series at Lanzhou station on the upper reaches of the Yellow River, prove that the significant periods of the annual runoff are 11, 6.25 and 3 years at Lanzhou station.The conclusion illustrates the feasibility of this method and provides scientific data for runoff forecasting. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

Wave-Based Study for Cable Tension Measurement of Cable-Stayed Bridge WANG Jun, WANG Feng-quan, ZHOU Xing-de Journal of Applied Sciences    2005, 23 (1): 90-93.   Abstract （291）      PDF（pc） （184KB）（64）       Knowledge map    Save The basic theory of cable tension measurement and its examination technology by the method of vibration wave are introduced in this paper.In practical measurement, it has found that stress wave excited by the sinusoid impulsion contains too much noise, so the time difference between two signals could hardly be discerned.According to the theory that the maximum modular values of wavelet transform signals and random noises have different spreading characteristics, wavelet sym3 which has approximately symmetric character is adopted to decompose the noise signal, and each wavelet transform coefficient is conducted by different soft threshold.The noise-extracted signal which is reconstructed by the revised wavelet coefficient could clearly reflect the time difference between incidence wave and reflection wave. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

A Study on the Void Distribution of Porous Materials Being Dried GE Shi-fu, SHI Ming-heng Journal of Applied Sciences    2005, 23 (1): 94-98.   Abstract （317）      PDF（pc） （225KB）（76）       Knowledge map    Save Basing on the analysis of micro-structure and the experimental data of equilibrium moisture content of the porous construction materials, this paper studies the relationship between the equilibrium moisture content and the void distribution of porous materials.The results show that the void distribution obeys log arithmic normal function.According to this, the relation between the vapor pressure P(r)/PH and the moisture content of the porous materials in the falling rate drying period is obtained.The calculation result approximately agrees with the experimental data with only 3.01% root mean square error.In addition, the effects of the void distribution parameters μ, σ, the temperature and the moisture content on the vapor pressure P(r)/PH of the porous materials in the falling rate drying period are analyzed.The results can be used to study the heat and mass transfer of porous materials during the falling rate drying period. Related Articles | Metrics | Comments（0） Cited: Baidu(8)

Select

Analyzing Rotor Rotating Error Using Fractional Brownian Motion WANG Kai, LI Yan, ZHENG Jian-ming Journal of Applied Sciences    2005, 23 (1): 99-102.   Abstract （288）      PDF（pc） （186KB）（54）       Knowledge map    Save According to variance changing laws of a precise rotor radial rotating error motion, it can be proved that the rotor's motion track is characterized by fractional Brownian motion.Then non-dimension fractal box counting dimension has been adopted to describe the rotor's radial rotating error motion, and it also be taken as a parameter to estimate the complexity of axes motion track.At last, Hurst exponent was adopted to describe the stability of axes rotating motion. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

An Approximate Expression of the Effective Permittivity in the Inhomogeneous Difference Unit Grid BAO Xiu-long, LI Zheng-fan, SUN Xiao-wei Journal of Applied Sciences    2005, 23 (1): 103-107.   Abstract （305）      PDF（pc） （288KB）（64）       Knowledge map    Save By applying the circuit concept of series-parallel connection of capacitance, the approximate formulae of effective permittivities along x, y, z axes for various inhomogeneous cell grids are obtained.These formulae are combined with the FDTD scheme and MRTD method of the arbitrary spatial grid to calculate the resonant frequency of resonance cavity under the condition of numerical stability.This method can save computing time and memory than the conventional FDTD method.These effective permittivities formulae are also applied in the difference method for other electromagnetic problems. Related Articles | Metrics | Comments（0）

Select

Joint Source-Channel Coding/Modulation Based on NN YIN Wei-wei, LI Rong-wei, WU Le-nan Journal of Applied Sciences    2005, 23 (1): 108-110.   Abstract （264）      PDF（pc） （148KB）（109）       Knowledge map    Save A new JSCCM scheme based on a probabilistic neural network is proposed.The complexity and delay in this system is less than the traditional one and it is more robust against channel errors.Simulation results demonstrate that the performance of the JSCCM is far better than that of the tandem coding modulation system. Related Articles | Metrics | Comments（0）

Select

The Application of Discrete Measurement Event in Hybrid System State Estimation MO Yi-wei, XIAO De-yun Journal of Applied Sciences    2005, 23 (2): 111-116.   Abstract （258）      PDF（pc） （287KB）（79）       Knowledge map    Save By defining the discrete measurement event (DME), extra quantitative values can be extracted from quantized qualitative measurement signals.Together with continuous quantitative signals, this quantitative information acquired from quantized qualitative signals is used in hybrid state estimation to improve state estimation results and acquire better estimation performance.The application scheme of these extra quantitative values in hybrid state estimation is discussed in this paper.Moreover, its design steps and the method of implementation are given.The feasibility of the proposed state estimation approach based on DMEs is validated by simulation experiments.Simulation results show that DME can improve the speed and precision of state estimation in hybrid system. Related Articles | Metrics | Comments（0）

Select

A Novel Chip Equalization Algorithm for Sparse Channels WU Qi-hui, ZHAO Chun-ming, GAO Zhan Journal of Applied Sciences    2005, 23 (2): 117-121.   Abstract （327）      PDF（pc） （234KB）（82）       Knowledge map    Save High-speed packet transmission is an important characteristic in the 3rd generation mobile communication system.The chip equalization technique is one of the important methods that enhance the performance of the high-speed packet transmission in the low spreading factor.For sparse channels, a novel RLS (SMRLS) algorithm is presented.Theoretical analysis and computer simulations show that the performance of the SMRLS is superior to conventional Rake.The new algorithm maintains the steady-state MSE of the conventional MRLS approximately, while the convergence speed is increased and computation complexity is reduced greatly.It proves to be of great value in practical application. Related Articles | Metrics | Comments（0） Cited: Baidu(8)

Select

The Application of PBSV-DDM in EM Scattering Analysis of Electrically Large 2-D Objects AN Xiang, LÜ Zhi-qing, HONG Wei, CUI Tie-jun, YIN Xiao-xing Journal of Applied Sciences    2005, 23 (2): 122-125.   Abstract （304）      PDF（pc） （202KB）（66）       Knowledge map    Save A new highly efficient domain decomposition method based on the partial basic solution vectors (PBSV-DDM) is presented for solving arbitrary electrically large 2D electromagnetic scattering problems. Different from the traditional domain decomposition method (DDM) by which one needs to solve matrix equations in each sub-domain during every iteration till convergence, which is considerably inefficient and time-consuming, the matrix equations in the new PBSV-DDM algorithm could be solved for a set of standard orthogonal excitation vectors to get the partial basic solutions.Then the solution in each sub-domain is obtained only by a simple vector summation operation in every iteration procedure.Obviously, the computational efficiency would be greatly improved.The validity and computational efficiency of PBSV-DDM have been verified by numerical examples. Related Articles | Metrics | Comments（0）

Select

Image Restoration Based on the Modified Paik-Hopfield Neural Network HAN Yu-bing, WU Le-nan Journal of Applied Sciences    2005, 23 (2): 126-130.   Abstract （263）      PDF（pc） （227KB）（89）       Knowledge map    Save In this paper, a modified Paik-Hopfield neural network model based on the new state updating rule is proposed for restoring a degraded image.The convergence, the residual error and the energy change of the full parallel mode are thoroughly studied.An improved iteration algorithm based on the idea of "from coarse to fine" and the difference estimation between two adjacent layers is also presented.Experimental results demonstrate that this method can approximate the minimum of the energy infinitely and greatly improve the speed of convergence as well as the precision. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

The Design and Implementation of the Authentication Service in WLAN Based on ACE LI Jing, CAO Xiu-ying Journal of Applied Sciences    2005, 23 (2): 131-135.   Abstract （286）      PDF（pc） （233KB）（68）       Knowledge map    Save Describes the authentication service in the IEEE802.11 MAC specifications and the concurrent programming mode are briefly described.The design and implementation plan of the authentication service in WLAN based on ACE is also presented. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

The FDTD Analysis of the Nonlinear Lumped Element CAI Peng, YANG Xue-xia, XU De-ming Journal of Applied Sciences    2005, 23 (2): 136-139.   Abstract （306）      PDF（pc） （195KB）（81）       Knowledge map    Save Two kinds of nonlinear lumped elements are analyzed by the FDTD algorithm.The improved nonlinear lumped network (INL2N) -FDTD method has been used to analyze the Schottky diode in more than one FDTD grid cells.The Gunn diode has been analyzed by an effective set of FDTD iterative formulas.The analysis results are in good agreement with the relevant literature and the results of the SPICE. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

A Study on Low Complexity PCGC Decoding Algorithms LI Jin, XU Xiao-dong, JIANG Ming, YOU Xiao-hu Journal of Applied Sciences    2005, 23 (2): 140-143.   Abstract （292）      PDF（pc） （203KB）（67）       Knowledge map    Save The parallel concatenated gallager code (PCGC), a new kind of channel code which concatenates the low density parity check (LDPC) code in parallel, can be decoded in the two-layer iterative style.The PCGC decoder has good performance, but its high computation complexity interferes with its hardware implement.In this paper two kinds of low complexity PCGC iterative decoding algorithms, and the simulation results prove that the algorithms have excellent performance are proposed. Related Articles | Metrics | Comments（0） Cited: Baidu(6)

Select

Design of a Disturbance Reduction Controller for a Class of Nonlinear Systems with Multiple State and Input Delays WANG Zhan-shan, ZHANG Hua-guang Journal of Applied Sciences    2005, 23 (2): 144-148.   Abstract （320）      PDF（pc） （207KB）（89）       Knowledge map    Save To cope with the unmeasurable external disturbance having known waveform but unknown magnitudes, a disturbance compensator is designed for a class of nonlinear systems with multiple state and input time-variant delays.When the unbounded disturbance enters the time-delay systems, the systems state variables will go out of control.Thus it is necessary to design a reduction controller to compensate or minimize the effects of the disturbance.In order to obtain the estimation of state and disturbance, an augmented system is constructed by the nonlinear system and the disturbance system, and a time-delay composite state observer is designed to give the estimation of state and disturbance.Hence, the disturbance reduction controller is derived and the systems state variables are kept in control.An illustrative example shows the effectiveness of the proposed methods. Related Articles | Metrics | Comments（0）

Select

A Study of the Timing Recovery Method for OFDM on the Digital AM Broadcasting System RUI Hua, XU Da-zhuan, ZHU Qiu-ming Journal of Applied Sciences    2005, 23 (2): 149-154.   Abstract （325）      PDF（pc） （376KB）（80）       Knowledge map    Save OFDM is an effective modulation technique for high-rate and high-speed transmission over the frequency selective fading channel.However, the OFDM system can be extremely sensitive and vulnerable to timing synchronization errors.In this paper, a low-complexity two-stage timing recovery scheme is proposed. The timing recovery process can be divided into symbol synchronization and sample clock synchronization.In the former process, an improved ML algorithm is proposed.Its performance can approach the optimal ML algorithm without estimating SNR and therefore can have lower complexity.In the latter process, an simple synchronization algorithm is proposed using scatter pilots to estimate sample clock phase errors, and a low pass loo p filter is used to track the symbol timing drift caused by sample clock frequency offset.Simulations are carried out on DAMB channels, and the results indicate that our proposed scheme can achieved good performance and are robust to multipath fading channels.Its low complexity enables the scheme to operate easily run on the DSP chip. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

An Equalization Multi-thread Scheme to Realize IEEE802.11 MAC Protocol CHEN Li-quan, HU Ai-qun, HU Jun, LI Wei-zheng Journal of Applied Sciences    2005, 23 (2): 155-159.   Abstract （306）      PDF（pc） （247KB）（66）       Knowledge map    Save There are 22 models in the finite state machine of IEEE 802.11 MAC protocol.When a single thread or multi-thread schemes are used to realize this MAC protocol, the equalization between efficiency and realization is not easily achieved.The proposed equalization multi-thread scheme can realize the balance between system efficiency and feasibility.The results from simulations also support this point. Related Articles | Metrics | Comments（0）

Select

A Signal Processing Method for the Coriolis Mass Flowmeter Based on a Normalized Lattice Notch Filter NI Wei, XU Ke-jun Journal of Applied Sciences    2005, 23 (2): 160-164.   Abstract （367）      PDF（pc） （212KB）（113）       Knowledge map    Save An adaptive normalized notch filter is applied to filter the sensor output signals of a Coriolis mass flowmeter and calculate its frequency.An adaptive line enhancer based on the above-mentioned notch filter extracts the required signals from the noisy data.The sliding Goertzel algorithm is used to calculate the real time phase difference between two signals of this kind.With the frequency and phase difference obtained, the time interval of the two signals and the mass flowrate are derived.The simulation results show that the algorithms studied in this paper are efficient. Related Articles | Metrics | Comments（0） Cited: Baidu(258)

Select

The Design of a Payment Gateway Emulator for the TPC-W Benchmark and Its Performance Analysis LUO Zhen, LI Sheng-li, XIE Xia Journal of Applied Sciences    2005, 23 (2): 165-168.   Abstract （329）      PDF（pc） （198KB）（66）       Knowledge map    Save The architecture of TPC-W benchmark is introduced briefly in this paper, which followed by description of the schema of payment gateway emulator (PGE) and its interactive authentication process with the server under test (SUT).It compares the performance of web server with and without the payment gateway emulator and then analyzes its performance with the change of test mode and database size.The result shows that TPC-W benchmark can simulate the true behavior web server so as to evaluate server's performance exactly with different workload by changing the parameters within the range of possibilities and find the performance bottleneck. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

The Effect of MOSFET Output Impedance on Linearity in the CMOS Gilbert Mixer TANG Shou-long, LUO Lan, LU Sheng-li Journal of Applied Sciences    2005, 23 (2): 169-173.   Abstract （297）      PDF（pc） （245KB）（104）       Knowledge map    Save The nonlinearity behavior of the CMOS Gilbert mixer is investigated.The impact of MOSFET output impedance on distortion is studied in depth.The mixer nonlinear model and optimal drain-to-source voltage bias are presented in this paper.The rate of error between the analytical predictions and the Cadence SpectreRF circuit simulation results is less than 10%. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

The Recursive Constant Modulus Algorithm for Fast Moving-Targets Tracking GUO Yan, LI Ning, LI Li, FANG Da-gang, PEI Yu-ling Journal of Applied Sciences    2005, 23 (2): 174-177.   Abstract （284）      PDF（pc） （192KB）（76）       Knowledge map    Save A new blind beamforming algorithm to fast track several movable users was proposed in this paper. Instead of forming independent beams at different times by the conventional method, the information of the users' DOA obtained from the previous beamforming is made full use of.It can greatly speed up the subsequent beamforming and lead to enormous saving in the required real time computations.Therefore, the new beamforming algorithm could keep up with the moving targets more quickly, which is of great importance in real communication systems.Simulation results confirm our ideas. Related Articles | Metrics | Comments（0）

Select

An Efficient Diagnosis Algorithm for the Test of Embedded SRAM REN Ai-ling, LING Ming, WU Guang-lin, LI Rui Journal of Applied Sciences    2005, 23 (2): 178-182.   Abstract （311）      PDF（pc） （217KB）（83）       Knowledge map    Save This paper puts forward an self-diagnosis bit-oriented algorithm(MARCH-TB +), according to the testing algorithms,we use a shared built-in-self-test structure(parallel structure) to test and diagnose embedded SRAM(2k×1).The experimental results show that the proposed testing algorithm has high fault coverage, strong diagnostic ability and requires less testing time. Related Articles | Metrics | Comments（0） Cited: Baidu(8)

Select

The Design of Low Distortion High Speed Sample/Hold Circuit XIA Wei-yi, WU Jian-hui Journal of Applied Sciences    2005, 23 (2): 183-186.   Abstract （347）      PDF（pc） （188KB）（76）       Knowledge map    Save A low distortion, high speed switched capacitor sample and hold circuit has been designed.A novel bootstrapped switch is used to degrade the nonlinearity and the method to decrease the settling time of the amplifier is proposed.The simulation shows that it achieves more than 70 dB linearity at a sampling rate of 40 MHz. Related Articles | Metrics | Comments（0）

Select

ANN-CE: An Improved Neural Network Method for Predicting DNA Binding Sites XU Dong, WANG Yi-fei Journal of Applied Sciences    2005, 23 (2): 187-191.   Abstract （250）      PDF（pc） （225KB）（85）       Knowledge map    Save The neural network technology has achieved great success in the field of bio-sequence analysis.But a neural network based on MSSE is not the final solution to the problem of predicting DNA binding sites.In this paper, An improved neural network method, ANN-CE, to predict DNA binding sites is presented.It is a three layered back-propagation neural network in which the error function is a cross entropy function.The result shows that the predicted sensitivity and specificity of ANN-CE increased by 11.40% and 11.91% respectively compared with the back-propagation neural network based on MSSE with the same architecture. Related Articles | Metrics | Comments（0）

• page
• Page 1 of 4
• Total 143 records
• First page
• Prev page
• Next page
• Last page