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2007 Vol. 33, No. 04

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Fatigue analysis for civil aircraft fuselage typical truss joint in serving environment
Zheng Xiaoling, Bao Rui, Fei Binjun
2007, 33(04): 379-382.
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Fatigue analysis for civil aircraft fuselage typical truss joint in serving environment was discussed, in which detail fatigue rating (DFR) method in corrosive environment was used. A way was presented to determine DFR-corrosion-influence-factor of structural element in serving environment by the DFR-corrosion-influence-factors obtained by tests with detail simulation specimens in typical laboratory environments. A pre-corrosion and corrosion-fatigue alternated experiment, corresponding to a given serving condition, with typical truss joint simulation specimen of civil aircraft was conducted. The comparison between the analysis conclusion and the test result shows the validity of the method.
Effects of two-dimensional interference on pressure distribution of a circular disk
Gao Lei, Wang Jinjun, Zhang Panfeng
2007, 33(04): 383-387.
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The effects of two-dimensional disturbance, induced by a circular cylinder placed upstream, on the aerodynamic characteristics of a circular disk have been investigated in wind tunnel. The pressure distribution on the windward surface of the disk was studied with different cylinder diameters and spacing distances. The mechanism of the passive flow control method was discussed combined with previous flow visualization experiments. When the non-dimensional spacing (L/D) between the cylinder and the disk is below 0.7, the low-pressure area on the windward surface of the disk expands rapidly with the spacing increase. While the spacing ratio L/D is greater than 0.7, the low-pressure area keeps in a constant value with the increase of the spacing (the cylinder has the same diameter), and the low-pressure area increases with the cylinder diameter increase. In addition, this disturbance technique can reduce the drag of the disk, and the maximum drag reduction is up to 9% of that of the isolate disk. The corresponding drag of the cylinder-disk system can be reduced by about 4%.
Quick algorithm for designing emergency orbital transfer scheme
Shi Jun, Han Chao
2007, 33(04): 388-391.
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A quick algorithm for designing emergency orbital transfer scheme that can meet the requirements of measure, fuel and time during emergency orbita l transfer was presented. The orbital transfer mode suitable for variable search was given. The question of designing orbital transfer scheme quickly was transf ormed into the question of restricted optimization. And the entire mathematics m odel of measure restrictions was established and the corresponding algorithm for measure restrictions was presented. Orbital transfer scheme, that is required n ot only to meet measure restrictions, but also to achieve optimal goal, was foun d by using genetic algorithm. Cases of calculation show that the orbital transfe r schemes designed by using this quick algorithm can meet the need of emergency orbital transfer mission.
TVD scheme and numerical simulation of aerodynamic heating in hypersonic flows
Xie Jinrui, Wu Songping
2007, 33(04): 392-396.
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In order to get more accuracy results for heat transfer in chemical non-equilibrium hypersonic flow simulations, a new entropy correction function in TVD (total variation diminishing) scheme was presented. By study of characters of the flow in boundary layer, an anisotropy entropy correction function was used in the TVD scheme instead of the isotropy entropy one, the new coefficient in the entropy correction function, which is varied according to the distribution of the pressure in the flow field, was adopted. The numerical test of the chemical non-equilibrium hypersonic flows over sphere verifies the new entropy correction function. The flow field and the surface heat transfer rate were obtained by the numerical simulation. The results show that the new entropy correction function can improve the accuracy of surface heat transfer as well as the flow field in numerical simulations. The new entropy correction function can also improve viscosity resolution near the surface. The surface heat transfer rate, which is calculated by using new entropy correction function, is less sensitive to the size of grid in normal direction near the surface.
Endoatmospheric interceptor fast response control using impulse attitude control motor
Wang Jin, Chen Wanchun, Yin Xingliang
2007, 33(04): 397-400.
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The effectiveness of aero control decreases as dynamic pressure decreases. Therefore impulse attitude control motor(ACM) is to be used to maintain fast response of missile in low dynamic pressure. A preliminary study of the method was given. The impact of ACM on the dynamics of missile was analyzed using assessment data. Then a control strategy was designed on the pitch plane after some simplifications. Aero-fin was used to counteract the aerodynamic moment so that the total aerodynamic moment would be zero and the attitude of missile would be mainly controlled by ACM. ACM control strategy was designed with the assumption that the increment of pitch angle was equal to the increment of angle of attack. Simulation results were given for step acceleration command which show that aero control is effective as ACM control in high dynamic pressure and ACM control becomes more effective than aero control as dynamic pressure decreases.
Heat transfer analysis using ANN with experimental data of 180° turn channels with rib turbulators
Ding Shuiting, Wei Xia, Tao Zhi, Xu Guoqiang
2007, 33(04): 401-404.
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The heat transfer character inside the 180° turn channel with variable cross-section and different rib turbulators was studied by experiment. The channel is the middle part of a gas turbine blade. The data set evaluated by the experiment was processed by dividing the channel into several sections. A feed-forward neural network based on back-propagation algorithm (BP) was evolved with levenberg-marquardt(LM) algorithm and Bayesian regularization, and a model was established for the result referred before using BP net. It is validated by being compared with curve regression that it is available to use artificial neural networks (ANN) to predict heat transfer character of channel inside a gas turbine blade. And it-s much more efficient than curve regression.
Near real-time optimization for reentry trajectory of RLV
Wang Qi, Ding Yunliang
2007, 33(04): 405-408.
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Determining how to find the best controls of a re-entering reusable launch vehicle (RLV) so that it is able to safely reach the terminal area energy management (TAEM) involving the solution of a two-point boundary value problem. This problem, which is considered to be difficult, is traditionally solved on the ground prior to flight. The optimal controls are found regardless of computation time by most of algorithms. But it-s very necessary to find the optimal controls quickly for some flight tasks. Traditional trajectory optimal algorithm can not shoulder this fast optimization task. In that work, a new hypothesis was introduced according to the features of constrained three-dimensional reentry trajectory of RLV. The set of dynamics and kinematics equations of motion was divided into two sets and only one set equations participate in the optimization iteration algorithm, which improves the efficiency of optimization greatly. Then the methods of multipliers was used to deal with the terminal constraints. Later the conjugate-gradient method was applied to evaluate the optimal reentry trajectory. Successful results show the algorithm is able to generate a feasible reentry trajectory in 10 s on the desktop computer.
Optimization design for aeroelastic dynamics of T-tail
Lü Bin, Tan Shengang, Wan Zhiqiang, Yang Chao
2007, 33(04): 409-413.
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Due to complicated configuration and multi control surfaces, the flutter characteristic design of T-tail is complicated and there are many parameters in the process of establishing dynamics finite element model, so the designers face more difficulties. In order to solve these problems , optimization methods was introduced into design process. According to the virtues of genetic algorithm and sensitivity algorithm, the two methods are mixed for natural vibration optimization and ordinal applied for flutter optimization respectively. The sensitivity formulas about natural frequency and flutter damp to structure parameters were discussed, and the math models about optimization design were established. With the methods using for structural dynamics optimization of a real T-tail model, not only the time of designing has been reduced to a great extent, but also the design precision has been assured, with the error of natural frequency below 3%. The flutter speed increased with the mass of structure minimized, and the result provides references in practical structural design.
Integrative design model and algorithm for nano-satellite-s radiator surfaces and heat insulation layers
Li Yunze, Ning Xianwen, Wang Xiaoming, Zhuang Damin
2007, 33(04): 414-417.
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Passive thermal control system is very important for Nano-satellite′s temperature control and its working safety. The calculations of radiator surface area and heat insulation layer thickness are necessary for the design of passive thermal control system. A set of integrative design equations and algorithms were developed and described for the calculation of radiator surface area and heat insulation layer thickness through the heat transfer analysis of nano-satellite′s radiator surface and the multi layer heat insulation. The working flow of this integrative thermal design model and algorithm was also introduced. A sunsynchronous orbit Nano-satellites thermal design using this integrative model and algorithm was given as an example. The design example was analyzed and simulated. Result shows that the integrative design radiator surface and heat insulation layer can lead to a satisfactory thermal control effect, and a convenient design model and algorithm for nano-satellite′s passive thermal control system design is provided.
Film bleeding on internal cooling in rectangular channel
Ding Shuiting, Hou Xiaojing, Xu Guoqiang, Deng Hongwu
2007, 33(04): 418-421.
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An experimental study was made to obtain heat transfer data in a rectangular channel with two ribs and nine holes. The objectives were to investigate the effect of mass flow ratios and bleed holes area ratio on internal cooling. Test was performed with single bleed hole as well as with multiple holes. Steady-state heat transfer coefficients were obtained using thermochromic liquid crystal. The heat transfer enhancement was observed to largely depend on the placement of bleed hole on the inter-ribs surface. It was found that the area-averaged Nusselt number was enhanced more by placing the bleed hole behind the rib. The best enhancement occurred between 6% and 8%. The heat transfer of effective was improved obviously when the Renolds number was low relatively. Some conclusion can be obtained that the heat transfer was enhanced at the regions from the edge of holes to downstream section. The influence of area flow ratio was also tested. It was found that the best area flow ratio was about 2.5%~3.0%.
BTT missile autopilot design based on dynamic inversion
Zhang Yan, Duan Chaoyang, Zhang Ping, Chen Zongji
2007, 33(04): 422-426.
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Autopilot design for BTT (bank-to-turn) missile is difficult because of its complex nonlinear characteristics and strict flight states limit by ramjet engine. The non-minimum phase phenomenon was discussed while direct dynamic inversion method was adopted. New BTT missile control system framework was proposed using two-stage idea based on dynamic inversion. The first stage is inner loop design based on dynamic inversion to ensure the performance of attack angle, sideslip-angle and roll rate tracking. Command converters from normal acceleration to attack angle and roll angle to roll rate are the core of the outer loop on the second design stage. They are separately based on neural networks and dynamic inversion for normal acceleration and roll angle command tracking. 6 DOF (degree of freedom) simulation results show the ability of three channels- decoupling control and robustness of the proposed scheme, demonstrating its feasibility in engineering field.
Robust stabilization of uncertain nonholonomic kinematic systems
Li Chuanfeng, Wang Chaoli
2007, 33(04): 427-430.
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Lots of research on the stabilizing problem of certain nonholonomic kinematic systems has been developed. However, when the geometric parameters of systems are unknown, especially, considering uncalibrated vision measure in control systems, kinematic systems are uncertain. The stabilizing problem was investigated for a kind of uncertain nonholonomic control systems, i.e., nonholonomic mobile robots. A robot kinematic model with two driven wheel velocities as control inputs was obtained through the observation and analysis of mobile robots driven by two wheels with the different center of mass and geometric center. A smooth time varying stabilizing controller was proposed for these systems with the known wheel radius and the distance between the two driving wheels. For the circumstance with the unknown two parameters above, a robust stabilizing law was presented also. The asymptotic stability was rigorously proved for the closed loop systems by using the proposed control laws. A heuristic idea may be obtained for developing stabilizing problem of general uncertain nonholonomic control systems by considering this kind of design. The simulation illustrates the effectiveness of the proposed controllers.
Control of chaotic oscillation for helicopter rotor blade
Liang Tingwei, Wang Qi
2007, 33(04): 431-434.
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The flapping model of rotor blade can be expressed as the model of Duffing′ oscillator with periodic exciting force in the dynamic balance test of helicopter rotor. To control the chaotic vibration in flapping, a method of changing exciting signals in Duffing′ model was proposed to restrain the chaos state in Duffing′ system. To couple a triple-period exciting signal in Duffing′ model, with the analytic method of Melnikov′ function based on chaos analysis, the chaos threshold of Duffing′ function were analyzed in the states of periodic exciting signal only, triple-period exciting signal only or combined action of the two signals respectively. Simulation experiments were also conducted according to the three kinds of exciting signals. The results indicate that the chaos range is reduced more evidently by coupling the triple-period exciting signal than that by period exciting signal only.
Teleoperating system of Stewart platform based on VR
Wang Zhifeng, Wang Zhanlin, Fu Yongling, Wu Qiang
2007, 33(04): 435-439.
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The virtual system for teleoperating Stewart platform based on VR (virtual reality) technical was designed. The principle of the drive arithmetic for the virtual model was instructed. In this arithmetic, firstly proper coordinate system was established, and then a series of coordinate transform was adopted, so the movement correspond problem was solved. The neural network based on L-M training algorithm was used to solve the forward kinematics problem of the platform, and proved that the neural network had a very good generalization performance by experiment. Based on bounding volume hierarchies, the axis-aligned bounding boxes was selected to detect the collision in the virtual simulation system. A sort of simple control strategy was used to overcome the stability of the system because of the time-delay of the communicate link. In the local robot control system, the discrete form of tracking-differentiator was selected to ensure that the robot has good stability and well dynamic performance. The virtual system was validated to be effective by experiment finally.
Investigation of cloud detecting for satellite images based on immune coding principle
Zheng Hong, Cao Qiong, Han Yu
2007, 33(04): 440-444.
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To utilize the texture diversity of clouds and land in remotely sensed images, a novel describing method for image targets identification with complex background was proposed. The properties and classification of object image describing immune primitives was computed by the correlation between antibody property and the specificity of amino acid residues. The affinity formula of the training image-s immune primitives was presented by statistical analysis, which bears an analogy with the lowest amino acids combinative energy according to the biological immune antibody coding principle, to achieve the finite dimension object image features- optimize combination. Furthermore, The methodology was employed in the cloud contamination area detection. The cloud antibody has been configured and the cloud antibody has been tested on 200 images and more than 97% of results were correct, which proofed the validity of immune describing method for object image recognition in complex background.
Novel road detection and tracking algorithm for aerial images
Li Shuxiao, Chang Hongxing
2007, 33(04): 445-449.
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A novel road detection and tracking algorithm for intelligent pilotless aircraft applications was illustrated. Initially, synthetic image was extracted from electron road maps to initialize the road areas. Then, road detection was expressed as a minimizing problem by means of using distance transformation of input image and edges of synthetic image. Finally an iterative algorithm took shape and was applied to solve the minimizing problem mentioned above to abtain road regions. Road tracking method initialized its corresponding minimizing problem utilizing the prediction image out of the detection results of previous video frames. Concerning the function of this method, strict experimental results are presented to demonstrate the satisfactory performances of our approach with its highly stability and adaptability.
Application of multistage influence diagram game theory for multiple cooperative air combat
Zhong Lin, Tong Mingan, Zhong Wei
2007, 33(04): 450-453.
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In order to make maneuvering decisions in uncertain environments, the influence diagram theory and game theory were introduced to maneuvering decision making in multiple cooperative air combat and the cooperative influence diagram game model was presented. Firstly, the principles that the large group air combat is converted to the air combat of several small teams were determined. Then, multi-target vs. multi-target model was converted to single target vs. single target model under the ideal of the cooperative air combat consideration. Last, the influence diagram game theory was used to solve the one on one air combat. The pilots- game optimal control sequences were obtained by solving the influence diagram game with a moving horizon control approach. The simulation results show the model is more effective than the cooperative differential game under condition of uncertainty.
Robust localization algorithms for outdoor mobile robot
Zong Guanghua, Deng Luhua, Wang Wei
2007, 33(04): 454-458.
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On the basis of Pioneer3-AT wheeled outdoor mobile robot, coder, gyro, compass and RTK-GPS were used for the robot localization. A new kind of federated Kalman filter was designed in which data from multiple sensors were fused stage by stage. Data of odometry and gyro were fused firstly. Then the fusion data were fused with data of compass. Data of RTK-GPS were fused finally. This filter could filter the fluctuation and compensate error accumulation of sensors and could achieve good precision of robot localization. In city environment, RTK-GPS would lose difference state frequently because of the shelter of buildings, so the precision of RTK-GPS was not steady. This filter could choose different measurement error covariance matrix by the precision of RTK-GPS, which made the filter adapt well to the change of RTK-GPS precision automatically, so the localization algorithm was robust. Experiment results show that robot can achieve the localization precision about 0.4 m steadily.
Statistical analysis of step-stress accelerated life testing for repairable product
Li Xiaoyang, Jiang Tongmin, Li Meijun
2007, 33(04): 459-462.
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During step-stress accelerated life testing (SSALT), in order to evaluate life and reliability characteristics of repairable product, the equation principle of accumulative hazard functions under two different stress levels was put forward. On the base of the rule, time conversion function was presented. After failure data were converted to the same stress condition by the way of iterative algorithm, the three-parameter Weibull process that includes the position element with Peck accelerated model was utilized to fit them. This model assumed "minimal repairing" such that any repair had no impact on the failure rate. By the use of maximum likelihood estimation, life and reliability of repairable system under normal stress conditions could be extrapolated. Residual distribution sampling was used to generate the two simulation examples. Results show that the model and method proposed is not only good at parameter evaluation with high accuracy in comparison with the traditional,but also can be applied to reliability growth testing.
Point cloud multi-view registration and integration technology based on automobiles-bodies RE design
Zhou Yu, Du Farong, Gao Feng, Qu Weiwei
2007, 33(04): 463-466.
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As the automobiles-bodies point cloud had the traits of large geometric dimension, huge data and rigor reverse precision, one registration and integration algorithm based on the framework points was put forward. The algorithm-s basic idea is to construct the framework points of vehicle model and the mark points of the separate point cloud, to search the mapped relationship between framework points and mark points using congruence triangle principle and to match the vehicle point cloud using the improved iterative closest point(ICP) algorithm which can accelerate iterative speed. A vehicle point cloud registration example of one light truck proves that this algorithm-s accuracy on registration is exigent, the calculation speed is very fast and the algorithm is one effective method of matching vehicle body point cloud.
Simulation model resource discovery technology based on semantics for simulation grid
Hou Baocun, Li Bohu, Chai Xudong
2007, 33(04): 467-471.
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To solve the problem about the lack of the semantic description and discovery for the simulation model resources in the grid resource management middleware, the ontology technology was introduced and the description ontology was defined to implement the semantic description for simulation models. The semantic matching algorithm based on the ontology inference was presented. This algorithm maps the semantic matching degree to the continuous value in . Especially, this algorithm supports inputs/outputs composition-based matching of simulation model resources. The research result was applied to the implementation of the simulation model discovery service for simulation grid, and has achieved well validation in the typical application cases.
Formal modeling and analysis of UML statecharts
Yao Shuzhen, Jing Maozhong
2007, 33(04): 472-476.
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The structural and semantic features of UML statecharts are analyzed firstly, and the hierarchical colored Petri net(HCPN) is constructed to solve modeling issues,especially those related to hierarchical statecharts with composite states. The Petri subnet for a composite state is composed of input/output interfaces, a state-transition part and a history state part. The input/output interfaces are used to parse entry arcs and gather exiting arcs to/from composites respectively. The state-transition part realizes transitions of the internal states. The history state part deals with memory recovery and memory cleanup of history units. After abstracting semantic rules and constrains of entry/exit transitions, their descriptions and analysis techniques of composite states based on HCPNs are illustrated. Finally, in the view of safety of UML statechart, HCPN semantic representation for completeness, consistency and reachability of statechart is elaborated. Optimizing the design of complex systems the guide in theory and practice for further research on developing automatic verification tools is provided.
Forecast modeling for structural equation model
Wang Huiwen, Zhang Ying
2007, 33(04): 477-480.
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Based on the historical data, a forecast modeling method for structural equation model was discussed, where the future relationship between the system factors was described without future sample. By applying spectra of matrix, the covariance matrix was decomposed of eigenvectors and eigenvalues. Typical linear regression method was adopted to predict eigenvalues, and predictive method of orthonomal matrix based on rotations of principal axes was adopted to predict eigenvector matrix, so it structured a forecast method of covariance matrix. The maximum likelihood method was applied to estimate the parameters of future structural equation model. The experimental simulation illustrated main computational procedures of the predictive model.The results show a high precise of the predictive values. The agreement of the final computation results with the experimental data indicates this method could be used to analyze and forecast structural equation model.
Design and implementation of model repository testing based on metamodel and JUnit
Huang Long, Guo Yufu, Wu Ji, Jin Maozhong
2007, 33(04): 481-485.
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To solve repository testing problem of test models in model driven testing, the single element, single test metamodel and combination of test metamodels coverage criteria were proposed. Test cases were generated by instantiation method and test verdict problem was discussed. The model repository testing project was implemented by JUnit framework on Eclipse platform. The effect of execution efficiency with different quantitative test cases and the relation of different test coverage criteria and corresponding JUnit test code scale were analyzed. Then practical instructions were given for test metamodel design and repository. The test results indicate that JUnit framework could be used to metamodel based testing. An automatic test framework-JMetamodel based on JUnit and metamodel was proposed which could be used for model repository and transformation testing.
Cloud model based algorithm for global optimization of functions
Zhang Guangwei, Kang Jianchu, Li Hesong, Li Deyi
2007, 33(04): 486-490.
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Numerical optimization of given objective functions is a crucial task in many scientific problems. Based on the outstanding characteristics of cloud model on the process of transforming a qualitative concept to a set of quantitative numerical values, and integrate with the basic principle of genetic algorithm, a novel adaptive evolutionary algorithm for continuous global optimization problems was proposed. With the instructions of qualitative knowledge, the extent of searching space is self-adjusted and the possibility of premature and the probability of trapping in local best optimization are greatly reduced, so the algorithm can find high accurate numerical solution within a short time. The algorithm avoids the process of coding and crossover so it is easy to be carried out. By the experiments on typical test functions, the precision, stability and convergence rate were well proved.
On reliability model of IEEE-1394b network interconnections
Duan Jingyuan, Zhang Chunxi, Shi Jieqin
2007, 33(04): 491-494.
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To solve calculable problem of IEEE-1394b network interconnection reliability, based on IEEE-1394b topology, a task based analysis method of system reliability was proposed, a reliability model of IEEE-1394b interconnection system was developed and the system reliability matrix definition was shown. To accord with IEEE-1394b characteristic, the definition of IEEE-1394b interconnection matrix was proposed.Model analysis of IEEE-1394b interconnection system in avionic system was made. Task routes, single route failure probability and task routes reliability were presented. The relay ports influences were analyzed and the conclusion is that relay ports influence IEEE-1394b interconnection system most.
Optimal block distribution in carry-skip adders
Cui Xiaoping, Wang Chenghua
2007, 33(04): 495-499.
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A new type of optimal block distribution algorithm of two level carry-skip adder was described to determine optimal block distribution sizes. According to this algorithm, with the given total worst case delay, the maximum optimal block distribution sizes of the adder for that delay can be determined. It is simplified to obtain optimal block distribution of any desired adder sizes. The carry skip adder optimal block sizes can minimize critical path delay. The analysis of gate delay and complexity were provided. Although the two-level carry skip adder with optimal block distribution uses a few extra gates, it provides better speed than the adders with fixed size blocks. The adder has been functionally verified and simulated by using PSPICE. The simulation analysis of time delay reveals that the two-level optimal block distribution carry-skip adder can provide faster speed than the carry-skip adder with fixed size blokes.
Predictive modeling on multivariate linear regression
Wang Huiwen, Meng Jie
2007, 33(04): 500-504.
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Based on the historical data, predictive method of multivariate linear regression model was discussed, where both future multivariate regression parameters and the performance evaluation statistics were estimated without future data. Prediction to the regression parameters was converted to predict cross product matrix of the variable augmented matrix. By applying spectral decomposition, cross product matrix was decomposed of eigenvectors and eigenvalues. Predictive method of orthonomal matrix based on rotations of principal axes was adopted to predict eigenvector matrix, where rotated angles from Givens transformation were obtained, and regular predictive models were built on both the angles and eigenvalues, respectively. The experimental simulation illustrates main computational procedures of the predictive model. Besides, the results show a high precise of the fitted values and a statistical validity of the predictive values. The agreement of the final computation results with the experimental data indicates this method could be used to analyze and forecast regression relationships of dependent variable to independent variables in many application fields.

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