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2006 Vol. 32, No. 07

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Three dimensional turbulence numerical simulation of rotor in forward flight
Yu Ziwen, Cao Yihua
2006, 32(07): 751-755.
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The flow field and performance of a helicopter in common forward flight and forward flight near the ground were analyzed using CFD (computational fluid dynamics) technique. The general governing equations of turbulent flow were set up, and were directly solved by finite volume method and SIMPLER (semi-implicit method for pressure-linked equations revised) approach in Cartesian coordinates. The spinning rotor was represented as time-averaged momentum source terms distributed along the span of the rotor with functional relationship to the local flow conditions in N-S(Navier-Stokes) equations. K-ε turbulence model and wall function method were included in the calculation method. The calculated results for flow field and performance correlation show good agreement with the measured data. Therefore, the numerical simulation technique is proved to be feasible for analyzing design issues of a helicopter.
Position and pose estimation by celestial observation for lunar rovers
Ning Xiaolin, Fang Jiancheng
2006, 32(07): 756-759.
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At a given time the altitude and azimuth of celestial bodies measured by star sensor and other celestial body measure devices contain the information of lunar rover’s position and pose. So the position and pose of lunar rovers can be determined using this kind of information. A new autonomous position and pose estimation method for lunar rovers based on celestial observation and unscented kalman filter(UKF) method was described. The principle of this method was introduced, and the rover motion models and the measurement equations of altitude and azimuth used in this autonomous celestial navigation system were presented. Because this method only uses the accuracy measurement coming from the star sensor, it has higher precision of position and pose determination. A simulation result demonstrated the validity and feasibility of this new method.
Analysis of nonstationary random vibration data during lift-off
Yuan Hongjie, Tang Huan, Jiang Tongmin
2006, 32(07): 760-763.
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The locally stationary parametric model was established to analyze the nonstationary random vibration environment of aircraft during lift-off. The computation of a time-varying spectrum was decomposed into two separate operations, one to define the time-varying mean square value of the signal, and the other to define the spectral properties of the signal. The wavelet transforms were used to separate the nonstationary vibration signal into the deterministic signal and random signal. Specifically, the time-varying mean square value of the signal was computed using the entire signal bandwidth,and the averaging time could be made short without causing a large bias error. Conversely, the basic spectra character of the signal was computed using the entire signal duration, and the frequency resolution bandwidth could be made small without causing a large random error. The vibration environment of aircraft during lift-off was obtained by concluding the auto-spectra of stationary random vibration.
New algorithm of solving for ranges during final approach of spacecraft rendezvous
Zhu Renzhang, Lin Yan, Zhang Lei
2006, 32(07): 764-768.
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A new algorithm of solving for ranges during the final translation phase of spacecraft rendezvous and docking using computer vision system was presented to determine relative attitude and position between target and chase spacecraft by Quaternion Estimation. In this algorithm for ranges, a weighted objective function was constructed according to target pattern and geometry feature and used for solving for ranges. For both non-planar (such as three-point T-type and five-point pyramid type) and co-planar patterns (such as square, rectangle and rhombus), the objective function contained terms concerning ratios of distances between the target spots; but for co-planar targets, the objective function had another terms which describe co-planar feature. Gauss-Newton method was applied to solve for the optimum range solutions of the least squares problem. For quadrilateral patterns, the initial values for iterations were given by coordinates of virtual image of the intersection point of two diagonal lines. Extensive simulations, conducted for various target patterns with image coordinates errors, show that the range algorithm presented is quite effective for the relative state determination.
Investigation of random error model for fiber optic gyroscope
Wang Xinlong, Du Yu, Ding Yangbin
2006, 32(07): 769-772.
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The performance of gyroscope decides the accuracy of inertial reference system. In order to diminish the error of the gyroscope and to improve its precision, the gyroscope′s error model was accurately founded. Methods of PSD(power spectrum density), ARMA, and Allan variance were federally used to study of the error speciality and modeling technology of the FOG(fiber optic gyroscope). The Allan variance and PSD were utilized to analyze the output of the FOG, and some main noise of the fiber optic gyroscope could be extracted and confirmed, then the performance of ARMA and AR of the FOG was evaluated. By analyzing the practical data of the FOG, it is shown that Allan variance and PSD are identical with analyzing the error of the fiber optic gyroscope, and ARMA is an effective method to found the random error model for the fiber optic gyroscope.
Precise research on stellar horizon atmospheric refraction model
Hu Jing, Yang Bo
2006, 32(07): 773-777.
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The concept of stellar horizon atmospheric refraction is considered to be one of the most promising concepts for satellite autonomous navigation. However, the precision of the method is limited due to the uncertainty of the stellar horizon atmospheric refraction model. According to the rule that atmospheric density would vary with altitude, latitude, season and so on, the fixed altitude measurement model (25km) can be availably modified. Consequently, the navigation precision and dependability can be effectively improved. By thoroughly studying on the principle of the atmospheric refraction, the stratospheric atmosphere data, the atmospheric model and other factors related to the precision of the measurement model, a self-adapted continuous altitude (20~50km) measurement model was established, and then the system model with the orbit perturbation was established as well. Finally, a simulation experiment was performed by using the Unscented Kalman Filter programme, and an error analysis was achieved.
Numerical thermal analysis for leaded surface mounted plastic package
Gao Hongxia, Yu Jianzu, Xie Yongqi
2006, 32(07): 778-782.
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The numerical detailed model and compact model were created for plastic quad flat package(PQFP), and the accuracy of two models was verified by the measurement values. The steady thermal performance of PQFP was studied under harsh environment, and factors effecting on the inner and outer thermal resistances were analyzed. Results show that using the multi-layer structure is a perfect way to improve the thermal performance, and forced air velocity around the PQFP should be lower than 5m/s. The transient thermal performance of PQFP was discussed for two cases: pulse heat loads and the ambient air temperature varying with time. Thermal responses of the die were got, which could be used to study the thermal stress, disability, and signal fuzzy, and be a basis for improving package’s thermal design.
Fault detection for inertial measurement unit based on local approach
Xiong Kai, Zhang Hongyue
2006, 32(07): 783-787.
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The application of local approach for fault detection in stochastic dynamic systems was presented. It was demonstrated that the selection of samples numbers plays an important role in improving the performance of the local approach. And it was pointed out that by enlarging the number of samples, the ability of the technique to detect small fault will be enhanced significantly. It was shown that when the sample size n = 1, decision function of the generalized likelihood ratio (GLR) method is the same as that of the local approach. In order to illustrate the efficiency of the proposed method, the local approach was applied to detect fault of the redundancy micromechanical inertial measurement unit (IMU) with a dodecahedron configuration, and the experiment results confirm findings of the theory analysis.
Dynamic routing algorithm for LEO/MEO double-layered satellite networks
Yuan Zhe, Zhang Jun, Liu Zhongkan
2006, 32(07): 788-792.
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Double-Layered satellite networks consisting of LEO(low earth orbit) and MEO(medium earth orbit) satellites have advantages on networking and communication performances. Based on the advantages of MEO and LEO satellites in long-distance and short-distance communications respectively, a hierarchical and distributed dynamic routing algorithm named DLRA (double-layered satellite-network routing algorithm) was proposed. By controlling flood of link state information, LEO satellites could acquire local topology information to route the short-distance traffics. The long-distance traffics were routed in MEO layer. The residual lifetime of the ISL (inter-satellite link) was considered in the path weight calculation in this algorithm. The selected path was optimal in path delay and duration. The simulation results show that DLRA has better performances in end-to-end delay, routing overhead and traffic flow distribution, and is easy to be applied.
Robust human-imitating intelligent control for a class of nonlinear systems
Liao Daozheng, Zhang Minglian
2006, 32(07): 793-796.
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A robust human-imitating intelligent control was proposed for nonlinear systems. Firstly, a human-imitating qualitative control law was developed through the analyses of the physical model of the plant. The qualitative control law was quantified by some method of parameter-optimization based on the nominal model of the plant. Then, on the basis of the developed human-imitating controller, a robust compensator was proposed to overcome the bad influences resulted from modeling errors, unmodeled dynamics and disturbances. The compensator was derived by Lyapunov stability theory, thus the stability of the closed-loop system was guaranteed. However, the specified Lyapunov function usually essential in a common Lyapunov-based approach was not needed during the design ofthe robust compensator, as a result, the difficulties in designing the Lyapunov function for a nonlinear system was conquered. Applying the proposed scheme to control a double inverted pendulum, the results of experiment verify the validity of this design.
Design and implementation of GPS ground-based regional integrity monitoring system for China civil aviation
Zhu Yanbo, Zhang Xiaolin, Xue Rui, Zhang Miaoyan
2006, 32(07): 797-801.
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A GPS(global positioning system) GRIMS(ground-based regional integrity monitoring system) was established by considering the particularities of Chinese terrain and the distribution of air traffic flow. A ground-based monitoring network composed of 7 monitoring stations gathered data of all GPS satellites in view and made primitive judgments of GPS satellites′ health from all the data gathered. The judgments and important original data were then sent to master station. All RAIM(receiver autonomous integrity monitoring) holes in Chinese airspace, as well as positions of all airplanes of Chinese airlines, were calculated in master station. All airplanes that were considered to be in any RAIM hole would receive a notification message. The time limitation of the whole process from gathering monitoring data to the notification be received was 7s. GRIMS is used in China civil aviation and improvs both safety and efficiency.
Implementation of low ripple switching power amplifier for magnetically suspended flywheel system
Zhang Liang, Fang Jiancheng
2006, 32(07): 802-806.
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To reduce the ripple current of standard two-level pulse width modulation (PWM) switching power amplifier for magnetically suspended flywheel system, a novel three-level PWM switching power amplifier was proposed. The ripple current of the switching power amplifier using two different PWM techniques was computed. The analysis results of ripple current indicate that the three-level PWM switching power amplifier can be used to significantly reduce the ripple current and meet the requirement for low power consumption. A novel simulation method of three-level PWM switching power amplifier was presented, based onSIMULINK. The method can analyze the characteristics of the system accurately and so offer direction for designing and debugging actual switching power amplifier. The comparison of a concrete switching power amplifier working in different PWM techniques by using simulation and experimental method was made. The agreement of the final simulation results with the experimental results indicates the proposed method is effective and feasible.
Interferometric signal simulation based on fractal modeling
Chen Yihong, Yuan Yunneng
2006, 32(07): 807-810.
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INSAR (interferometric synthetic aperture radar) signal simulation methods were investigated deeply, and the fundamental principle of the INSAR simulation was presented. Various noise interference factors in INSAR images were analyzed. The simulation model of the INSAR system was discussed in detail, which indicated that the precise model was very important for the INSAR simulation. Present general simulation models were compared and their disadvantages in INSAR simulation were also analyzed. Based on the self-affine fractal theory, the real interferometric process was simulated and the DEM (digital elevation model) satisfying space sampling rate was acquired. Results demonstrate that not only the stochastic properties and geometric distortion phenomena of ground targets,which are particular for radar interfermetry, are reflected vividly, but also the various distortion factors can be analyzed quantitatively. It is helpful to verify all kinds of interferometric arithmetics and optimize INSAR system design.
Implementation of IF signal processing in GPS satellite signal simulator
Li Baozhu, Zhang Qishan, Yang Dongkai
2006, 32(07): 811-814.
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With the technique of software radio in digital interpolation, digital filtering, A/D(analog/digital) converter, a mathematic model for signal processing of digital IF(intermediate frequency) in the GPS satellite signal simulator was established, and the approaches achieving the practical hardware design was implemented. The algorithm and design model for the circuit implementation was verified and optimized with Simulink in Matlab, the processing from digit base-band signal to analogue IF signal generation was achieved. The signal processing frequency was reduced to the best of our abilities for the circuit, and the processing area in the board for the high frequency signal was minimized. With the Xilinx′ ISE development tool and FPGA(field programmable gate arrays) using Verilog, the design and emulating of digital IF was implemented,and the digit signal was also analyzed with FFT(fast Fourier transform algorithm) frequency spectrum.
Near-field three-dimensional radar synthetic aperture imaging based on stolt interpolation
Li Liang, Miao Jungang, Jiang Yuesong
2006, 32(07): 815-818.
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A fully 3-D image-reconstruction algorithm that quasi-monostatic mode is used and the transmitting antenna works in step frequency was developed.The algorithm is not restricted by far field as the traditional imaging algorithm. Through synthetic aperture processing for radar data, the resolutions of the image and the detecting ability of radar are improved .A new Stolt interpolation method , which can increase accuracy of interpolation and reduce computation time, was presented. 3-D image of the objects can be achieved through the fast Fourier transform after interpolation. Numerous imaging results from simulations and experiment were presented. These results show that the algorithm for 3-D image-reconstruction based on this interpolation method can produce a microwave 3-D image with high resolutions.
Development of teleoperation testing system for Stewart platform
Wu Qiang, Wang Zhanlin, Li Jia
2006, 32(07): 819-822.
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Teleoperation testing system for Stewart platform was developed to study Stewart platform teleoperation stability under condition of large time delay. Ethernet was used to simulate the telecommunication channel, which linked two Stewart platforms control systems. DirectX technology was used to build user input interface and video feedback without consideration of hardware. Open graphic library(OpenGL) technology was used to establish virtual operation environment, through which time delay could be compensated. To obtain higher accuracy, neural network forward kinematics solution, instead of traditional methods, was used to drive virtual models. Communication bandwidth was monitored online to assure operation command's priority. The continuity of video transmission was guaranteed by changing transmission rate. The result shows that platform is easily controlled by operator's command input, position and attitude information is feedback through virtual operation environment and video, testing system meets design requirements.
Use of aqueous organic silicone hydrophobic agent for hydrophobic treatment of A3 steel
Yang Chunmei, Zhu Liqun, Chen Yichi
2006, 32(07): 823-827.
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An aqueous organic silicone hydrophobic agent which was based on the matrix of a commercially available silicone emulsion and was prepared in the presence of a metal salt catalyst and a water soluble corrosion inhibitor of alcoholamine modified phytic acid was applied to treat A3 steel specimen. Factors such as the catalyst content, the modified phytic acid concentration, pH of the phytic acid solution and ratio of the emulsion to the phytic acid acting on water-repellent treating effect and stability of the hydrophobic agent were examined. Effect of the hydrophobic agent on the water-repellency under the process parameters such as different heat-treatment temperatures, dipping time and heat-treating time was discussed and the appropriate formula and procedure were determined as well. The results demonstrate that the contact angle of the said hydrophobic agent treated specimen is as high as 132°, while the corrosion resistance of the phosphatized steel surface after treatment by the said hydrophobic agent is enhanced obviously.
Finite element prediction of elastic properties of three dimensional and four directional braided composites
Li Diansen, Lu Zixing, Lin Xiaoming, Lu Wenshu
2006, 32(07): 828-832.
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A new finite element solid model was established based on the unit cell model of 4-step rectangular three-dimensional braided composites and the assumption of the yarns with the hexagonal cross-section. The surface of model is parallel to the surface of perform, which coincides with the actual configuration of 3D braiding composites and is suitable for the analysis of the mechanical properties. The model also considered the relationship between braiding angle and internal braiding angle. Based on the model, the elastic constants of material were calculated by the ANSYS software and the numerical results showed good agreement with the experiment results. The influences of the braiding angle and fiber volume fraction on the elastic constants were also analyzed. The stress field of composites was determined, which provided a basis for the strength prediction.
Numerical simulation of laser welding in combustion chamber case shell on aeroengine
Wang Su, Wang Chunxia, Guo Jungang
2006, 32(07): 833-837.
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A numerical analysis modeling was created about the case shell on aeroengine combustion chamber, which is one of the crucial parts of the aeroengine, during the process of laser welding. Welding deformation due to circumferential welds at the joint between the two cylindrical shells was studied using the finite element analysis method based SYSWELD. Temperature field, welded joint stress field and deformation in laser welding at case shell were simulated. Heat resource problems during welding were analyzed and discussed from the point of mathematics, based on which the analysis result was qualitatively discussed combined with the factual conditions of the whole case shell for validating the feasibility of the method. The analysis will provide a theoretic reference for factual case shell welded, and is helpful to the improvement of the case shell welding craft methods. The method is also a reference to settle similar problems in welding fields.
Interval analysis for free vibration of composite laminated beams
Qiu Zhiping, Qiu Wei, Wang Xiaojun
2006, 32(07): 838-842.
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A new method named interval analysis method, which solves the free vibration of composite laminated beams with uncertain parameters, was presented. Based on interval mathematics and Taylor series expansion, uncertain parameters were described by interval numbers. Instead of conventional probabilistic approach, interval analysis method could get the variation intervals of the natural frequencies of structure, in which the bounds on the magnitude of uncertain parameters were only required, not necessarily knowing other information of statistics. From the comparison between the non-probabilistic interval analysis method and the probabilistic approach in the numerical examples, it could be seen that the region of the natural frequency of structures with uncertain parameters obtained by the interval analysis method contained that produced by the probabilistic approach. In other words, the width of the maximum or upper and minimum or lower bounds on the natural frequency yielded by the probabilistic approach was tighter than that produced by the interval analysis method. The result illustrates the feasibility and the efficiency of the interval analysis method.
Modeling and control implementation of virtual maintenance simulation
Zhou Dong
2006, 32(07): 843-846.
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It is insufficient to describe maintenance process and relevant resources with existing modeling technique, and existing methods are deficient to combine the expression of maintenance task and maintenance action simulation. Therefore, MTN (maintenance task net) was proposed in order to solve the integration of maintenance task description and maintenance action simulation.The framework of MTN including definition module, drive module and control module was constructed. The three key factors of MTN including state, action and condition based on the style of Petri net was biult. State could define maintenance resources such as human, tools and equipments.Action could define simulation process of behavior.Condition decided the constraint of state and action. MTN could drive virtual scene display system to run simulation and also could control the whole process. A case of LRU(line replaceable unit) disassembly was applied and the result proves that MTN model is valuable for the simulation and analysis of maintenance task.
Mobility behavior for driving bubble traversing constricted capillary tubes
Cao Yu, Zhang Zuoguang, Zhao Weijuan
2006, 32(07): 847-851.
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Constricted capillary tubes were used in order to study bubble mobility condition in composite material during cure processing. The effects of bubble length, radius of capillary tube and the variety of liquid on the drive critical condition of a single bubble traversing through a joint of flow channel of constricted capillary tubes were studied. The results demonstrate that the critical pressure difference of bubble traversing through joint of constricted capillary tubes perpendicularly decreases with the increase of bubble length or the radius of capillary tube, and is also affected by the variety of liquid obviously. The experimental result tallies with the theoretical results, and the study has a certain reference value to optimize cure processing to reduce and remove voids in composites.
Direct position analysis of nine-link Barranov truss based on Dixon resultants
Wang Pin, Liao Qizheng, Wei Shimin, Zhuang Yufeng
2006, 32(07): 852-855.
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The assembly configurations of a kind of non-planar nine-link Barranov truss were analyzed by using Dixon's resultants. Four equations were established for the four loops of the mechanism by using vector method and they were changed into complex exponent numbers form. Dixon method was adopted to construct a 22×22 Dixon matrix and then the greatest common divisor of two columns was extracted. After expanding the determinant of the matrix, a 64 degree univariate polynomial equation was obtained and 6 extraneous roots were canceled in the process of solving the other 3 variables. The same result could be obtained by using homotopy continuations method. A numerical example is given and it verifies that the number of assembly configurations of this kind of Barranov truss is 58.
Optimal design of parallel mechanisms with large tilting ability based on redundant actuation
Bai Zhifu, Han Xianguo, Chen Wuyi
2006, 32(07): 856-859.
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Orientation space of parallel mechanisms was analyzed. Physical constraints and singular constraints are the two main reasons which restrict the orientation ability of parallel mechanisms. The corresponding solutions from the two aspects were presented. New joints and redundant active UPS(universal prismatic spherical) link were used to enlarge the orientation space of a 3PRS(prismatic revolve spherical) parallel mechanism. The detailed design process of this mechanism with 90° tilting ability was carried out. Genetic algorithm was used to optimize the gross dexterity of the mechanism. Computer simulation showed the effectiveness of these results, which provided references for the wide application of parallel mechanisms.
Comparison of multi-objective optimization methods on engineering design
Zheng Yuntao, Fang Jie, Cai Guobiao
2006, 32(07): 860-864.
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Several multi-objective optimization methods in common use were concluded. In two examples of bi-objective optimization for cantilever beam and rocket engine, linear weighted method and gradual easy constraint method and neighborhood cultivation genetic algorithm(NCGA) method were used to obtain Pareto Front. Ideal point method with p-module, the least distance method, ideal point method with max-module and goal programming method were used to obtain non-inferior solutions. The goal point was performed with diverse specific point that corresponded to diverse result in cantilever beam optimization. The optimal solution was respectively found from all non-inferior solutions by dualistic relative comparison and fuzzy related degree method. Examples indicate that multi-objective optimization methods and identification methods of the optimal solution are efficient and reliable applying to the general multi-objective optimization problems.
Design of content-based video retrieval system using MPEG-7
Xue Ling, Li Chao, Xiong Zhang
2006, 32(07): 865-868.
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A content-based film video retrieval system named SupEye using MPEG-7(multimedia content description interface) was designed, which consisted of three parts: feature extraction, data storage and feature retrieval. The part of feature extraction took charge of the extraction of video features and video abstraction, in which assumptions and algorithms of video structure analysis and video abstraction were described on the basis of analysis on film video features. Data storage focused on the storage of video and feature data, in which multimedia content description files were divided into video features description and user interface description to improve retrieval performance through the usage of users′ retrieval features. The part of feature retrieval proposed a three-layered framework for multi-feature video retrieval which was composed of presentation, logic and transaction layer. On the basis of the analysis of MPEG-7, SupEye separates video features from user retrieval features and resolves the problems of feature analysis in sample query and the fusion of multi-feature query.
Identity-based authentication scheme for mobile ad hoc networks
Chen Wei, Long Xiang, Gao Xiaopeng
2006, 32(07): 869-872.
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In order to realize secure and efficient mobile node authentication in mobile ad hoc networks (MANET) which have no traditional public key infrastructure (PKI), a scheme consisting of identity-based cryptograph, distributed secrete sharing algorithm and elliptic curves encryption was proposed. Identity-based digital signature algorithm was briefly discussed. Lagrange interpolating polynomial was used to distribute master secret key among system nodes. A model describing secure node key issue was given, and a distributed procedure based on the given model was presented to securely issue node key by using elliptic curves encryption. The security and efficiency of the proposed algorithm was analyzed. According to the property of the bilinear pairing, the generation and update of session keys was discussed. The proposed authentication scheme could be used to realize efficient and secure authentication in distributed mobility scenarios, and to generate non-interactive one time session keys between two mobile nodes.
New model for token role-based access control on enterprise portal
Zhu Xiaojie, Xiong Zhang, Wu Jing
2006, 32(07): 873-876.
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Manage users and access rights are a complex and challengeable job in enterprise portal. Importing the role concept may simplify the access control, but its implementation is usually constrained by the single system and application. A new model,TRBAC(token role-based access control), was proposed for RBAC(role-based access control)on enterprise portal, which integrated the SSO(single sign on) technology and combined the RBAC model with token access mechanism. The role could span all web systems in portal. It was a token-based and dynamic-activated access control model, which could dynamically adjust the access rights according to user access requirement. It solved the problems on user management and access control management, and supported the corporate security standards, central auditing and control. The practice indicates that TRBAC improves the system efficiency and ensures the security.

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