2007 Vol.25

Please wait a minute...


For Selected: Download Citations EndNote Ris BibTeX Toggle Thumbnails

Select

Adaptive Subcarrier Allocation for Multi-user OSTBC-OFDM Systems LI Li, ZHU Guang-xi Journal of Applied Sciences    2007, 25 (1): 1-5.   Abstract （298）      PDF（pc） （246KB）（116）       Knowledge map    Save An adaptive subcarrier allocation algorithm for multiuser OSTBC-OFDM system is discussed in this paper. Aimed at minimizing the overall transmit power subjected to meet the target BER, an adaptive subcarrier general allocation algorithm with efficiency-priority is proposed.To achieve a desirable tradeoff between efficiency and fairness, all users are given a guaranteed transmission rate.An amendatory four-step algorithm with fairness constraint is described.Simulation results show that the proposed algorithms can improve BER performance of the OSTBC-OFDM system. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Statistics of Non-zero Mean Random Polarized Waves LI Yong-zhen, WANG Xue-song, WANG Lian-dong, XIAO Shun-ping, WANG Guo-yu Journal of Applied Sciences    2007, 25 (1): 6-10.   Abstract （320）      PDF（pc） （235KB）（109）       Knowledge map    Save Statistical characteristics of non-zero mean random polarized waves are studied based on the instantaneous polarization theory.Under a Gaussian hypothesis, probability density functions (PDFs) and joint PDFs of the amplitude, power and phase of random polarized waves are presented.The PDFs of instantaneous polarization projection vector (IPPV) of non-zero mean random polarized waves are then analyzed, which can entirely describe polarization characteristics of electromagnetic waves.Finally, relationship between the PDFs and the covariance ratio between two polarization channels are analyzed, assuming that the two polarization channels are independent.Conclusions drawn in this paper are useful to some applications such as dim signal detection and polarization measurement. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

A Power Control Method Based on Post-Detection SINR Balancing in Cellular V-BLAST Systems WEI Chuan-ming, QIU Ling, ZHU Jin-kang Journal of Applied Sciences    2007, 25 (1): 11-15.   Abstract （284）      PDF（pc） （233KB）（111）       Knowledge map    Save Power control is an effective technique to restrain the co-channel interference (CCI) in a cellular system.In this paper, an optimal power control method based on post-detection SINR balancing for a cellular V-BLAST system is proposed.Its simplified solution with reduced complexity is provided.The proposed method may balance the postdetection SINR of each substream at mobile stations (MS) by adjusting power levels of every transmit antenna at base stations (BS) in the system.Simulation results show that the proposed method outperforms existing power control methods both in the system outage probability and BER performance.The simplified solution significantly reduces computing complexity with slight performance degradation. Related Articles | Metrics | Comments（0）

Select

Low-Complexity Iterative Multiuser Detection Algorithm for Asynchronous CDMA Systems MEI Zhong-hui, YIN Wei-wei, WU Le-nan Journal of Applied Sciences    2007, 25 (1): 16-20.   Abstract （317）      PDF（pc） （232KB）（110）       Knowledge map    Save This paper presents two low-complexity iterative multiuser algorithms:parallel soft cancellation probabilistic data association (P-SC-PDA) and successive soft cancellation probabilistic data association (S-SC-PDA) for asynchronous CDMA systems.The computational complexity of the proposed algorithms is just o(K3) where K is the number of active users.Simulation results show that performance of the S-SC-PDA algorithm is significantly better than P-SC-PDA.With information delivered by the decoder, if the user signals to be detected is arranged such that signals of users with high detection reliabilities are detected first, and those with low detection reliabilities are detected later, even better performance can be obtained with S-SC-PDA. Related Articles | Metrics | Comments（0）

Select

Improved Rate-Maximization-Based Adaptive Resource Allocation for Multiuser OFDM Systems WANG Yan-jun, CHEN Qian-bin, KUANG Yu-jun Journal of Applied Sciences    2007, 25 (1): 21-25.   Abstract （383）      PDF（pc） （231KB）（148）       Knowledge map    Save Optimal adaptive resource allocation algorithms are computationally complex and time consuming, which is unfavorable for real-time application.To overcome this shortcoming, a rate-maximization-based low complexity adaptive resource allocation is proposed for multiuser OFDM systems, which maximizes the overall data rate under the constraint of total transmit power and BER performance.Simulation results show that the algorithm has better performance in terms of fairness and computational complexity comparing with original algorithm. Related Articles | Metrics | Comments（0） Cited: Baidu(9)

Select

Optimal Capacity Method of Blast Architecture for SUC Detection PAN Wen, JIANG Zhan-jun, WANG Yan, YOU Xiao-hu Journal of Applied Sciences    2007, 25 (1): 26-29.   Abstract （310）      PDF（pc） （202KB）（101）       Knowledge map    Save When a blast system employs the successive interference cancellation (SUC) method to detect signal, the diversity orders of transmitter antennas are not equal to each other, resulting in the different statistical characteristic among the channels of different transmitter antennas.In this case, the antenna average energy allocation (AAEA) method is not optimal in achieving the largest channel capacity.In this paper, based on analysis of channel ergodic capacity of a blast system, an antenna optimization energy allocation (AOEA) method is proposed.It is proved by capacity upperbound analysis that, by employing this method, channel ergodic capacity can be maximized.Simulation results show that channel capacity is improved at low SNR with the AAOA method. Related Articles | Metrics | Comments（0）

Select

Security Analysis of MANET Routing Protocol JI Xiao-jun, TIAN Chang, ZHANG Yu-sen Journal of Applied Sciences    2007, 25 (1): 30-34.   Abstract （253）      PDF（pc） （220KB）（96）       Knowledge map    Save Secure routing protocol design and analysis is the core of the security problems in mobile ad hoc network.This paper uses strand space and BAN logic to prove plausible route property of secure mobile ad hoc network routing protocol. Our analysis indicates that security of mobile ad hoc network routing protocol is essentially based on agent authentication and message integrity between trusted nodes in the network, therefore traditional formal methods can also be used to analyze secure mobile ad hoc network routing protocols. Related Articles | Metrics | Comments（0） Cited: Baidu(5)

Select

Optimization of Spacer Distribution in a Field Emission Display Device GU Wei, LEI Wei, ZHANG Xiao-bing Journal of Applied Sciences    2007, 25 (1): 35-39.   Abstract （358）      PDF（pc） （284KB）（103）       Knowledge map    Save In a field emission display (FED) panel, spacers are used to support the anode and cathode substrate. Different distortions of the panel are generated with different spacer distributions.Because distortions of the panels change the distance between the anode and cathode substrates, the internal electric field and the uniformity of emission characteristics is influenced by the spacer distribution.This paper studies the panel distortions with polar spacers and thin wall spacers.It is shown that the equal-lateral triangle patterned spacers are optimal for spacer distribution.Compared with the traditional arrayed pattern, fluctuation of brightness uniformity is reduced by one third. Related Articles | Metrics | Comments（0）

Select

A Class of Preconditioners for MLFMA Based on CFIE LI Wei-dong, HONG Wei, ZHOU Hou-xing Journal of Applied Sciences    2007, 25 (1): 40-45.   Abstract （458）      PDF（pc） （344KB）（132）       Knowledge map    Save In this paper, preconditioners for multi-level fast multipole algorithm (MLFMA) are investigated.Based on its structure, the near-part of MLFMA matrix is split into a block-diagonal matrix, and incomplete lower matrix, and an incomplete upper block matrix.The block-diagonal matrices are LU decomposition.A series of preconditioners (DILU) are constructed.These preconditioners can save CPU time by greatly reducing the number of iterations.Some preconditioners require slightly increased memory size, while others even do not need any additional memory.Numerical examples compare efficiency of the preconditioners, and show validity of the accelerated algorithms. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Application of Ant Colony Algorithm in SRAM Hierarchical Partition GU Ming, YANG Jun, ZHANG Qi-chen, GAO Gu-gang Journal of Applied Sciences    2007, 25 (1): 46-50.   Abstract （260）      PDF（pc） （226KB）（103）       Knowledge map    Save On-chip SRAM is a basic and important macro block of SoC.SRAM hierarchical partition affects the power consumption, delay and area of SoC.In this paper a new kind of random optimization algorithm, ant colony algorithm, is proposed to solve the SRAM hierarchical partition problem.Experimental results show improved performance of the proposed method. Related Articles | Metrics | Comments（0）

Select

Application Layer Multicast-Like Search Engine Model Based on Mobile Agent LIAO Xiao-fei, LI Jin-sheng, HONG Pei-lin, XUE Kai-ping Journal of Applied Sciences    2007, 25 (1): 51-56.   Abstract （221）      PDF（pc） （283KB）（93）       Knowledge map    Save Search engine is the key in searching network resource.This paper proposes a search engine model based on the mobile agent technique and application layer multicast.Network simulations show that this model has better performance in terms of total search time and network load.It is suitable for designing and implementating search engine. Related Articles | Metrics | Comments（0）

Select

Bandwidth Measurement in Satellite Network ZENG Bin, LI Zhi-tang, WANG Wei Journal of Applied Sciences    2007, 25 (1): 57-62.   Abstract （236）      PDF（pc） （271KB）（103）       Knowledge map    Save Existing algorithms for bandwidth measurement are unable to achieve balance between real time performance and reliability for satellite communication networks.To solve the problem, an intervening model is proposed to analyze the relationship between packet pair dispersion and cross traffic.Using this model, packet pair spacing with higher accuracy can be achieved.An algorithm of fast probe packet group is also developed.Results of simulation under the GEO/LEO satellite network model show that the algorithm can measure the bandwidth with high speed and low network resource cost. Related Articles | Metrics | Comments（0）

Select

Load Shedding for Continuous Query Based on Sub-path Analysis WANG Jin-dong, ZHOU Liang, ZHANG Lei, DING Qiu-lin Journal of Applied Sciences    2007, 25 (1): 63-68.   Abstract （253）      PDF（pc） （278KB）（102）       Knowledge map    Save Load shedding caused by burst of input data stream is studied in this paper.The deficiency of current load shedding methods is discussed and characteristics of data stream and continuous query networks analyzed.Definition and restrictions of the problem are given.A load-shedding algorithm based on sub-path analysis is proposed to solve the problem.Analysis and experiments show efficiency of the algorithm. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

A New Density Control Algorithm for Surveillance Sensor Networks SHEN Yang, QI Wang-dong, DAI Hao, YIN Xiang-lan, CHEN Hua Journal of Applied Sciences    2007, 25 (1): 69-73.   Abstract （323）      PDF（pc） （244KB）（102）       Knowledge map    Save Density control is a key technique in surveillance sensor networks.In this paper, a new density control algorithm called Enhanced Sponsored Sector Coverage (ESSC) is presented based on the Sponsored Sector Coverage (SSC).The proposed method takes account of some drawbacks in the SSC algorithm and modifies it to minimize the active node number.Analysis and experiments show that ESSC can reduce the number of active nodes by up to 15%~25% in comparison with SSC while maintaining the network surveillance performance. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Ontology Clustering Based on Semantics ZHANG Lei, XIE Qiang, LI Ling-zhi, DING Qiu-lin Journal of Applied Sciences    2007, 25 (1): 74-80.   Abstract （402）      PDF（pc） （305KB）（114）       Knowledge map    Save Ontology clustering is an effective assistant means to integrate ontologies.However, studies on ontology clustering are rare.An ontology similarity computing method based on semantics is proposed.The method considers not only the concept, but also the attribute set and related concept set.Basic similarity threshold of concept is used to control probability to compute similarity of attribute sets.Semantic radius is used to control the scope of related concepts. Similarity matrix of ontology clustering is calculated using an ontology similarity method.An agglomerative hierarchical clustering algorithm is used for ontology clustering.Experiments show that semantic based ontology clustering can give satisfied results, and its performance is better than ontology clustering using the oMAP similarity method.The method has been applied in an aeronautical institute and played a special role in ontology integration. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

Gray Dynamic Model of Verification Cycle in Measuring Instruments and Its Application SU Hai-tao, YANG Shi-yuan, DONG Hua, SHEN Mao-hu Journal of Applied Sciences    2007, 25 (1): 81-84.   Abstract （308）      PDF（pc） （190KB）（106）       Knowledge map    Save We establish two gray dynamic models GDM(1, 1) of measuring instrument's verification cycle based on time and frequency sequences by using the statistical feature of examined data and a weighting method.For a specific case, vernier caliper for example, the model has high precision in fitting and prediction.The lifecycles can vary under different working conditions.Prediction results of the frequency sequence model are better than that of the time sequence model. Based on information integration, multi-sensor control and management control, a control and information subsystem for verification cycle and lifecycle is set up for a case of gray dynamic model and auto-manufacturing.The models can be used to produce process to help enterprise reduce error, flaw and cost. Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Time Delay Kinetics in Gene Regulatory Networks ZHANG Jia-jun, CAI Chuan-zheng, WANG Yi-fei Journal of Applied Sciences    2007, 25 (1): 85-90.   Abstract （338）      PDF（pc） （276KB）（137）       Knowledge map    Save Time delay kinetics are ubiquitous in gene regulation, because of the vast separation of time scales between the fast reactions like DNA-binding and dimerizations, and slow reactions like translation, transcription and degradation.We develop a stochastic model of the delay gene regulatory network, and study both deterministic monments evolution equations and modified Gillespie algorithm simulation numerically.For example, single gene delay autoregulatory network and double gene delay regulatory network are studied.We find that time delays tend to create oscillations in gene regulatory network, in agreement with experiment data. Related Articles | Metrics | Comments（0）

Select

Equivalent Dielectric Constant Theory for Optical Bistability in Nonlinear Thin Coated Composites GU Li-ping, GAO Lei Journal of Applied Sciences    2007, 25 (1): 91-95.   Abstract （340）      PDF（pc） （228KB）（95）       Knowledge map    Save With the dielectric constant method, the dielectric response for three-phase composite media, in which coated inclusions are randomly embedded in a dielectric host, can be regarded as that of two-phase composites.As a result, we are able to obtain the dependence of the local field on the applied field based on the spectral representation theory.Then, we adopt the Maxwell-Garnett approximation to investigate optical bistability (OB) of three-component composites in which non-spherical coated inclusions are randomly embedded in a dielectric host in the dilute limit.Numerical results show that the OB behavior is strongly dependent on the depolarization factor (L) of the particles.The field-dependent effective dielectric constant of the composites is also studied. Related Articles | Metrics | Comments（0）

Select

Weighted Summation of Wavelet Coefficients Model for Annual Runoff Prediction LI Ya-jiao, SHEN Bing, LI Jia-ke Journal of Applied Sciences    2007, 25 (1): 96-99.   Abstract （270）      PDF（pc） （200KB）（113）       Knowledge map    Save The method that analyzes the period characteristics of annual runoff with continuous wavelet transformation and wavelet variance has been widely used.However it only gives qualitative prediction results, but not quantitative results. Based on the primary qualitative method, we propose an annual runoff prediction model using weighted sum of wavelet coefficients of major periods to predict the periodic components.The method effectively takes advantage of the multiresolution characteristic of wavelet analysis, and can reduce prediction errors caused by trend components.The annual runoff data of Qianhe basin are used to build and check the model.The proposed method can provide better results useful in predicting annual runoff time series. Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

Gray Analysis for Correlation between Yarn Strength and of Cotton Fiber Quality LI Xiao-feng, WANG Jian-jun, MA Jie, ZHOU Yi Journal of Applied Sciences    2007, 25 (1): 100-102.   Abstract （257）      PDF（pc） （146KB）（111）       Knowledge map    Save We have found that the relationship between the cotton fiber quality and the yarn strength can be modeled as a gray system.This paper describes a detailed analysis of the system.The study shows that the yarn strength is strongly affected by the length of the cotton fiber.The index is also influenced by maturity of the fiber, but is insensitive to the diameter and strength of the fiber.The findings are consistent with practical observations, indicating that the gray system analysis is an effective method for parametrical analysis of yarn strength. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Design of Adaptive Interleaving in Wireless OFDM Systems XU Xiao-dong, JING Ya, YOU Xiao-hu, CHEN Ming Journal of Applied Sciences    2007, 25 (1): 103-107.   Abstract （284）      PDF（pc） （267KB）（117）       Knowledge map    Save In modern communication systems, only combined with interleaving techniques can error correction codes effectively improve the system performance.In wireless OFDM systems, adaptive interleaving techniques based on instantaneous subcarrier channel state information can break burst errors more effectively into random errors, achieving a better system performance than traditional block interleaving.This paper proposes an improved adaptive interleaving scheme that not only achieves a better system performance, especially the frame error rate (FER), but also reduces the algorithm complexity. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

Adaptive Determination of Micro-satellite Attitude Using Pseudo Gyro, Magnetometer and Earth Sensor YU Feng, LIU Jian-ye, XIONG Zhi, DUAN Fang Journal of Applied Sciences    2007, 25 (1): 108-110.   Abstract （315）      PDF（pc） （157KB）（94）       Knowledge map    Save Attitude determination is a key that affects the performance of a micro satellite platform.An adaptive extended Kalman filtering algorithm is presented in this paper for attitude determination consisting of a pseudo gyro, a magnetometer and an earth sensor.Attitude determination performance of a satellite on two orbits with different inclination is studied by simulation.The results indicate that roll and pitch accuracy is about 0.05ånd heading accuracy is better than 0.4°.The accuracy is improved as inclination decreases.When the earth sensor fails, roll and pitch accuracy of the satellite on the orbit with large inclination is better than 0.5°, and heading accuracy is about 1°.The adaptive Kalman filter can evidently enhance attitude determination performance. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Joint Estimation of Sampling Clock and Residual Frequency Offset of OFDM System Based on Discrete Preamble WEI Li;XU You yun;CAI Yue ming;WANG Deng lin Journal of Applied Sciences    2007, 25 (2): 111-111.   Abstract （2545）            Knowledge map    Save Estimation and compensation of sampling clock and residual frequency offset in OFDM systems are an important issue. Using discrete preamble, we derive near optimal and sub optimal estimation based on the maximum likelihood (ML) estimation theory, and then analyze the estimation performance and discuss the design of discrete preamble to achieve best estimation performance. We also give a closed loop scheme for accurate and fast sampling clock tracking. Validity of the proposed method is verified in simulation. Related Articles | Metrics | Comments（0）

Select

Detection of Weak Signal Based on Instantaneous Polarization LIU Tao;WANG Xue song;LI Yong zhen;XU Zhen hai;XIAO Shun ping Journal of Applied Sciences    2007, 25 (2): 117-117.   Abstract （2566）            Knowledge map    Save We study the detection of weak signal using narrowband dual polarization radar. Description of Instantaneous Stokes sub Vector Sequences (ISVS) of radar target signal and noise are presented. The statistics of ISVS and probability density functions of different signals are given, and a novel detection algorithm proposed through polarization and power accumulation in time. We also derive an analytical expression of false alarm probability and show that the constant false alarm rate (CFAR) of the new receiver can be made bounded. Simulation results show that the radar detection performance is improved. It is useful in applications such as anti radar stealthy, early warning and space detection. Related Articles | Metrics | Comments（0） Cited: Baidu(5)

Select

A Fast Optimal Configuration Algorithm for WDM Networks with PathProtecting pCycles GE Chen hui;SUN Xiao han;ZHANG Ming de Journal of Applied Sciences    2007, 25 (2): 124-124.   Abstract （2283）            Knowledge map    Save A new algorithm is proposed to quickly optimize WDM networks with path protecting p cycles. A heuristic method is considered to search the Mutually Disjoint Path Group (MDPG) set for each candidate p cycle. An Integer Linear Programming (ILP) model is introduced to design WDM networks with MDPG. Numerical studies show that the optimal results obtained with the MDPG ILP algorithm are all very close to the solutions of pure ILP method but with greatly reduced computational time for different network topologies. The optimization procedure tends to choose p cycles protecting connections that are completely straddling p cycles. Related Articles | Metrics | Comments（0）

Select

Multiuser Detection Algorithm Based on Diversity Combining and MMSE for FastMFSK/FHMA Communication System LIU Chuan qing;HU Xiu lin;ZHANG Yun yu Journal of Applied Sciences    2007, 25 (2): 129-129.   Abstract （2305）            Knowledge map    Save An optimization method has recently been presented by Brink to design the degree distribution of irregular LDPC codes using EXIT chart. Brink’s method is easier to visualize and program compared to density evolution, but it is unable to choose degree distribution automatically. An improved optimization algorithm based on EXIT curve fitting, DE EXIT, is proposed in this paper to overcome the drawback. The proposed algorithm can automatically choose an optimization degree distribution and obtain a corresponding ensemble threshold. Simulation results show that DE EXIT has a good performance and can be applied under different conditions to achieve optimal code structures. Related Articles | Metrics | Comments（0）

Select

Improved Optimization Algorithm Based on EXIT Chart for LDPC Codes XU Hua;XU Cheng qi Journal of Applied Sciences    2007, 25 (2): 134-134.   Abstract （2420）            Knowledge map    Save An optimization method has recently been presented by Brink to design the degree distribution of irregular LDPC codes using EXIT chart. Brink’s method is easier to visualize and program compared to density evolution, but it is unable to choose degree distribution automatically. An improved optimization algorithm based on EXIT curve fitting, DE EXIT, is proposed in this paper to overcome the drawback. The proposed algorithm can automatically choose an optimization degree distribution and obtain a corresponding ensemble threshold. Simulation results show that DE EXIT has a good performance and can be applied under different conditions to achieve optimal code structures. Related Articles | Metrics | Comments（0）

Select

A Fast and Precise Multimedia Inverse Quantization Algorithm DAI Lin;YANG Jun;FAN Zhi xiang Journal of Applied Sciences    2007, 25 (2): 141-141.   Abstract （2397）            Knowledge map    Save Nonlinear functions are essential in multimedia systems, but they are difficult to be implemented in fixed point SOC. In this paper, a method combining a lookup table and Taylor series is proposed to approximate nonlinear functions by considering the ability of fixed point SOC and the limitation of memory. In addition, a fast convergent method is presented to improve precision by only taking sixth order Taylor series. Experiments show that the proposed method needs less memory compared with the full lookup table method, and can greatly improve precision compared to the method proposed by Tsung Han Tsai [1] Related Articles | Metrics | Comments（0） Cited: Baidu(1)

Select

Determining Word Length of FixedPoint Accelerator in SOC Based on FloatPoint to FixedPoint Conversion ZHOU Fan;SHI Long xing;YANG Jun;ZHANG Yu;GAO Gu gang Journal of Applied Sciences    2007, 25 (2): 145-145.   Abstract （2908）            Knowledge map    Save Many multimedia and communication applications require dedicated hardware accelerator to achieve acceptable performance and cost in SoC. The word length of the computation unit or memory in hardware accelerator is important to the chip area and power consumption. This paper proposes a novel method for the design of word length of fixed point hardware accelerator based on float point to fixed point conversion from statistical perspective. The proposed approaches take into account the hardware architecture design and the software conversion together, solving the problem on a mathematical layer. In any case, the method can greatly reduce computation load, and implement multimedia calculations of high computational complexity without using a DSP chip. Related Articles | Metrics | Comments（0）

Select

Methane Conversion to Acetylene via Microwave Plasmas SUN Yong zhi;YANG Hong sheng;SUN De kun;SHEN Chang sheng Journal of Applied Sciences    2007, 25 (2): 152-152.   Abstract （1649）            Knowledge map    Save Related Articles | Metrics | Comments（0） Cited: Baidu(7)

Select

A Novel AGC Scheme Based on Control of Equalizer Error DENG Qing;ZHENG Wei shan;WU Jian hui Journal of Applied Sciences    2007, 25 (2): 157-157.   Abstract （2475）            Knowledge map    Save Traditional approaches of AGC acquire error control signals by estimating the average value over a long period of time. It results in complicated circuitry and is susceptible to intersymbol interference. In this paper, we present an equalizer based AGC approach that uses the equalizer’s error to adaptively compensate for the input signal and effectively reduces the complication of the hardware. Simulation results demonstrate good acquisition and tracking performances under circumstances of degraded signal. |Keywords： automatic gain control (AGC); equalizer; intersymbol interference Related Articles | Metrics | Comments（0） Cited: Baidu(3)

Select

WebOLAP System Based on Object Pool and Data Caching XIE Qiang;YU Ya li;DING Qiu lin Journal of Applied Sciences    2007, 25 (2): 161-161.   Abstract （2791）            Knowledge map    Save By analyzing the existing problems of traditional OLAP systematic in a web environment, a system structure of OLAP system based on object pool and data caching is proposed. The definition of data pool is given, and a processing user request algorithm is proposed. The definition of data cache and data cache processing algorithm are given. Object pool holds certain quantity of objects. An object is a function unit capable of providing decision support, which visits data in the data cache. If the data does not exist, it turns to the OLAP server so that the system performance can be greatly enhanced, and the OLAP server’s burden is lessened. Finally, system implementation and application results are discussed. Related Articles | Metrics | Comments（0）

Select

Extensible Storage Structure Based on Multidimensional Hierarchical Cube ZHAO Qing jian;CHEN Sen fa;HU Kong fa Journal of Applied Sciences    2007, 25 (2): 166-166.   Abstract （2343）            Knowledge map    Save As a multidimensional index structure, the multidimensional hierarchical B + tree is introduced, on which an expandable multidimensional hierarchical cube (MH-cube) is set up. With the hierarchical semantics, MH-cube may perform quick query, data updates and schema update with high efficiency. A theoretical analysis shows that the MH-cube is superior to other kinds of cubes. Related Articles | Metrics | Comments（0） Cited: Baidu(4)

Select

Layered Software Reliability Model of Component Based Software… LIU Jian hao;LIU Xiao ming;YAO Yi;HUANG Song Journal of Applied Sciences    2007, 25 (2): 171-171.   Abstract （2195）            Knowledge map    Save Reliability is an important characteristic in quality architecture. For a component based software system, based on path analysis and testing from operational profile, a system reliability model is built using characteristics of the component development process and the system development process that are mutually unrelated. According to the layers of path information and the particular degree of component information, the model can be used at the appropriate granularity. An actual model is shown by statistical testing data, and methods for improving accuracy of reliability estimation is proposed. Related Articles | Metrics | Comments（0）

Select

An Integrated Solution to Automate Treatment Procedure for WholeBody Gamma Knife ZHOU Zheng dong;LUO Li min;SHU Hua zhong Journal of Applied Sciences    2007, 25 (2): 177-177.   Abstract （2762）            Knowledge map    Save In order to automatically determine the treatment procedure of whole body gamma knife and improve treatment results, a novel method based on the geometric optimization of shots and optimization of treatment path is proposed. A geometric optimization model based on boundary box is designed to arrange the shots. Coverage percentages of tumor and normal tissues are taken into consideration in the objective function. The optimization problem is solved by genetic algorithm. Based on the shot optimization arrangement, genetic algorithm is applied to find the best treatment path. In case a large number of shots are needed, a layer by layer treatment path optimization scheme is used to reduce computational time. This way, treatment can be carried out regularly according to the optimized shot locations and treatment path. Application of the method to simulated data shows that the treatment procedure is more convenient and faster. Related Articles | Metrics | Comments（0）

Select

Combined Algorithm for Damping Attitude of Inertial Attitude and Head Reference System Based on Fault Detection ZHU Yan hua;LIU Jian ye;ZENG Qing hua Journal of Applied Sciences    2007, 25 (2): 183-183.   Abstract （2610）            Knowledge map    Save In a platform inertial navigation system, damping network is applied to damp the gyro’s drift. For strap down inertial attitude and heading reference system (SIAHRS), gyro’s drift error can also be suppressed by the information from accelerometers. This paper proposes the idea of calculating vehicle attitude by both gyros and accelerometers, and designs a damping Kalman filter to integrate this information. However, only when the vehicle was moving without acceleration can one use the output of accelerometers to calculate its attitude. For this reason, the residual chi square test is employed in the Kalman filter to detect vehicle movement in real time. Besides, effects of outliers from measuring sensors are also considered in order to enhance system’s fault tolerant ability and sensitivity. Results of static and dynamic experiments are carried out. Related Articles | Metrics | Comments（0） Cited: Baidu(2)

Select

Heave Motion Control for Submini Underwater Vehicle ZHAI Yu yi;CHEN Yong;GONG Zhen bang;TANG Hai bin;MA Jin ming Journal of Applied Sciences    2007, 25 (2): 189-189.   Abstract （2598）            Knowledge map    Save Based on the mathematical model used in a self designed underwater vehicle, a simulation model is induced. Reasonable simplification has been made in model. Having analyzed the overall performance, correction to the system using the PID algorithm is proposed. The PID parameters are calibrated, and its effects on the digital PID controllers are analyzed. Simulation has been performed with Simulink providing some useful results. Related Articles | Metrics | Comments（0）

Select

Experimental Study and Fractal Analysis of Ice Crystal Structure at Initial Period of Frost Formation HOU Pu xiu;CAI Liang;YU Wei ping Journal of Applied Sciences    2007, 25 (2): 193-193.   Abstract （2333）            Knowledge map    Save Using a system of image magnification and acquisition, we observed and collected pictures of ice crystal in various shapes under different growth conditions. The original pictures were converted into binary images, and fractal analysis was performed with the box counting dimension. The results show that the dentritic ice crystal has a fractal structure, and the fractal dimension can be obtained. However ice crystals that are not fully developed do not have a fractal structure. The meaning of fractal dimension is discussed. This study provides a basis for a frost growth model that is close to reality. Related Articles | Metrics | Comments（0） Cited: Baidu(17)

Select

Gray SelfMemory Prediction of Inflow to Hydropower Station Reservoir LI Li;SHEN Bing;LI Rong feng;ZHAO Chang sen Journal of Applied Sciences    2007, 25 (2): 198-198.   Abstract （2459）            Knowledge map    Save Combining the theory of gray system with self memory principle, a new model for predicting time series of reservoir inflow is proposed. The model has been used to predict the annual and flood period inflow to reservoir of Caohe Hydropower Station on the Jin River. The case study indicates that the model can deal with non stationary time series and provide the inflow trend and extreme values with improved accuracy. Related Articles | Metrics | Comments（0）

Select

Adaptive Robust Stabilization for a Class of Nonlinear Systems with TimeVarying Delayed Disturbance XU Jian qiang;CHEN Shu zhong Journal of Applied Sciences    2007, 25 (2): 202-202.   Abstract （2748）            Knowledge map    Save The problem of adaptive stabilization for a class of nonlinear systems including matching time varying delayed disturbance is discussed. The bound of the time varying delayed state disturbances are unknown, and are assumed to satisfy the linear growth conditions. By using the Lyapunov stability theory and Lyapunov Krosovskii functional, we propose a robust adaptive state feedback controller, which can guarantee that the closed loop system is globally stable in the sense of uniform ultimate boundedness, and the state trajectories uniformly asymptotically tend to zero. An illustrative example is given to demonstrate validity of the results. Related Articles | Metrics | Comments（0）

• page
• Page 1 of 4
• Total 127 records
• First page
• Prev page
• Next page
• Last page