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2007 Vol. 33, No. 06

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Design of target code in human-machine interface
Zeng Qingxin, Zhuang Damin, Ma Yinxiang
2007, 33(06): 631-634.
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An experiment of multitask (monitor, calculation-memory, attack and detection) which simulated the flight control environment with some degree of fidelity was developed. This work investigated how human identify target color, figure and location under different task weight and mental workload levels which achieved by changing working speed rhythm controlled by stimuli display and interval time through measuring their reaction time and accuracy to provide standards for target in human-machine interface design. Results indicate that green, red, square, rotundity and triangle can be used as target code in human-machine interface design, but blue not, no matter what mental workload and task weight are. It is necessary to evaluate attention allocation and take it as the basis for deciding target location in human-machine interface design. There is good performance when a multidimensional target displays in the form of display interval time more than 1s.
PIV measurements in the wake of coaxial-rotor in water tunnel
Yu Shimei, Deng Yanmin
2007, 33(06): 635-639.
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Particle image velocimetry (PIV) technique was applied to the experiment of coaxial-rotor in hover and in forward flight in water tunnel. The laser sheet was positioned for tip vortices shed at zero and 180 degrees azimuths. The rotor rotation and the imaging system were synchronized to acquire PIV images at specified rotor azimuth angles. Instantaneous vorticity and velocity distributions of the rotor flow fields were obtained. The tip vortices were tracked from their generation to convection downstream. The wake contractions in hover and the wake boundary inclination angles in forward flight were measured. The wake geometries and aerodynamic interaction characteristics of coaxial-rotor flow fields were investigated. For comparison, single-rotor flow fields were also measured. The agreement of the experimental results with the literatures indicates PIV is effective to investigate complex flow fields in water tunnel. The valuable results have important meanings to the aerodynamic calculation and reasonable design of coaxial-rotor helicopter.
Flutter control of aeroelasticity with freeplay nonlinearity
Li Daochun, Xiang Jinwu
2007, 33(06): 640-643.
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The question of active futter control of prototypical aeroelastic wing section in subsonic uncompressible flow was investigated. The aeroelastic dynamic model with freeplay nonlinearity in pitch was built using Theodorsen quasi-steady aerodynamic force and moment. Then the control law for flutter suppression was derived via state-dependent Riccati equation. For the synthesis of the controller, only pitch angle and control-surface deflection were measured directly. An observer was constructed to estimate the unavailable state variables of the system. The closed-loop system including the observer and nonlinear controler is asymptotically stable. The simulation results are presented, which show that the observer can give precise estimations for the plunge displacement and the velocities in pitch and plunge, and that the controller is effective for flutter suppression of two-dimensional airfoil with freeplay nonlinearity in pitch.
Analysis and simulation on the dynamic process of the air-blasting device
Wan Yuequan, Wang Shaoping
2007, 33(06): 644-648.
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To meet the need for a safe and effective device to clean the pipelines in the industry area, an air-blasting device was designed. The air-blasting device storages highly compressed air which could be got from air supplier and then, by suddenly releasing the compressed air, the supersonic jet current and shock waves will be generated. The shock wave and jet current will impact the wall of the pipelines to reduce the attaching dirt. The working process of this device was presented and the mathematic models of the dynamic process were built. Through simulation, the dynamic process was analyzed, and the distribution of the total pressure, velocity field, wall shear stress in the pipeline and the burst strength was given. The results show that the main energy of the cleaning force is from the shock waves and the jet current, not from the shear stress. And when using 10MPa compressed air, the cleaning scope is more than 160 meters at one time.
Design and calculation for the anti-icing system of an aircraft engine let
Chang Shinan, Ai Suxiao, Bi Wenming, Yuan Xiugan
2007, 33(06): 649-652.
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A hot-air anti-icing system for an engine inlet was designed. The engine had a flow distribution plate. Based on the calculation of water droplets trajectories, thermal calculation was conducted for the anti-icing system, including the temperature profile of anti-icing surface, pipes pressure loss and flux distribution. The calculation was used to examine if the designed system would work well under the design condition. The influences of air temperature, flux and restrictor diameter on temperature distribution of anti-icing surface were analyzed. The results indicte that the surface temperature increases with the increasing of hot-air temperature and flux, and that the surface temperature of the flow distribution increases with the increasing of restrictor diameter, while the effect of it on leading edge surface temperature can be neglected.
Partial-jet-borne flight LQG/LTR robust controller design
Tang Peng, Zhang Shuguang, Jiang Zaiming
2007, 33(06): 653-657.
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A research was done for the problem of the application of integrated flight/propulsion system of the aircraft using LQG/LTR(linear quadratic gaussian/loop transfer recovery) robust design methodology at the partial-jet-borne flight phase. With flying qualities assessed by bandwidth and Gibson criteria, and the robustness assessed by singularity values, the rule of choosing LQG/LTR design parameters was analyzed, including several influential factors, such as allocation of the attitude and rate command, effects of prefilters, presetting of disturbance level factor and effects of high frequency dynamics on the robustness and flying qualities. The controller design on a test aircraft configuration shows that compromise can be made between flying qualities and robustness by designing LQG/LTR robust controller, if the response type parameter and the disturbance level factor are suitably chosen.
Simulation of elastic-plastic impact with modified smoothed particle hydrodynamics method
Long Liping, Zhang Jianyu, Ding Hua, Fei Binjun
2007, 33(06): 658-662.
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Based on the approximation of smoothed particle hydrodynamics (SPH), the formulations of SPH method, which can numerically simulate the elastic-plastic impact process in solid mechanics, was established. Modified boundary functions were used to simulating the boundary condition. Owing to the tensile instability of traditional SPH, the code cannot get the proper result. The conservative smoothing approach was used in the procedure to filter the result and eliminate the tensile instability. The example of elastic-plastic impact of a pole and the comparison of the result calculated by SPH and finite element method (FEM) were given. The numerical example and analysis that indicated the influencing region of traditional SPH particle is lager than FEM, and the precision of SPH method is lower than FEM at the same scale of particles. The precision of SPH method can be improved by increasing the number of particles.
Numerical calculation of laminar flat plate skin friction
Zhou Dan, Yu Jianjun, Yan Chao
2007, 33(06): 663-667.
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In order to calculate laminar skin friction more accurately, the laminar flat-plate skin friction was calculated by solving the N-S equations. For solving the N-S equations, 4 advanced upwind schemes, 14 different grid distributions and 5 limiters were employed. All the results were compared with Blasius solution. The results show that the van Lee′s FVS(flux vector splitting)scheme has considerable numerical dissipation, it is also sensitive to grid quality and limiter, so it is unsuitable for friction calculation. The solution is more accurate with a higher limiter and scheme viscous resolution. The calculation precision strongly depends on the height of the first level mesh. Considering both of the calculation ability and the grid aspect ratio, the height of the first level grid can be reduced to improve precision. For skin friction calculation, there must be no less than 4 grid points in the boundary layer.
Spherical panorama creating algorithm based on curve surface mosaic
Li Xiaohui, Zhou Yinqing, Wang Zulin
2007, 33(06): 668-671.
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A novel spherical panorama creating algorithm based on curve surface mosaic was presented to achieve omni-directional scene observation at a fixed viewpoint. The work was concentrated on sphere projection, blank holes elimination, global illumination alignment and image stitching. The horizontal and vertical spherical projections were studied in detail, in which the 3-dimension spherical information was fully saved to avoid wrinkle unwrapping that occurred in traditional methods. Then a way of "inverse interpolation" was applied to eliminate image blank holes caused by discrete calculation. To reduce the great illumination differences between image sequences, a novel method of "dispersing cumulative error" was presented. The limits of traditional ways that were only for neighboring illumination alignment were released. The final mosaic on curve surface was accomplished by using a matching method based on image feature, and a smooth seamless spherical panorama was gained. The whole algorithm runs automatically, which has high performance in illumination alignment and spherical mosaic, and is valuable in practical application.
Fast PN code acquisition for DSSS receiver in high dynamic situation
Xu Feng, Shao Dingrong, Li Shujian
2007, 33(06): 672-676.
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For direct sequence spectrum system(DSSS) receiver in high dynamic situation, a fast PN code acquisition method was proposed. The acquisition method based on high-folded digital matched filter(DMF) and FFT is able to convert the traditional two-dimensional search method to one-dimensional search. The realization frame of 32-folder DMF in FPGA was put forward. The simulation focused on the folder multiple and system resource shows that the larger the folder multiple is, the lesser the system resource costs. When the input signal SNR is -20 dB, the acquisition speed of this method is much faster than the traditional methods. This method has good characteristics of fast acquisition and system resource expended lower. Practical engineering verification shows that it can be used in high dynamic situation.
Algorithm of decision making for avionic device fault diagnosis
Li Jie, Shen Shituan, Sun Baojiang, Qi Yi
2007, 33(06): 677-681.
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The multiple attribute decision making(MADM) algorithm for fault diagnosis expert system was put forward. The influence of diagnosis decision-making on the diagnosis efficiency was analyzed. According to the effect of every attribute on diagnosis decision-making,the attributes′ value was normalized. The linear additive weighting function was used to evaluate every fault priority. The weight value was determined by the preference information on the probability of fault occurrence. The approach of solving evaluation function correction vector was proposed to satisfy the jump characteristics on attribute boundary points. The enhancement of diagnosis efficiency under different conditions for the MADM algorithm proposed was strengthened by experimental analysis.
Hybrid FDTD-PWS method for focal field analysis of lens antenna at millimeter-wave band
Zhang Yan, Lü Shanwei, Miao Jungang, Li Yuying
2007, 33(06): 682-685.
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A novel hybrid finite-difference time-domain (FDTD) method and plane wave spectrum (PWS) method was presented for analysis focal field distribution of lens antenna. Firstly, the amplitude and phase distribution in the aperture was simulated by the FDTD method. Moreover, the antenna model was reduced to 1/4 by the pertect electric conductor (PEC) and perfect magnetic conductor (PMC) boundary conditions. And secondly PWS method was applied to calculate the focal field distribution. In order to demonstrate the accuracy and efficiency of this new method, a lens antenna at millimeter-wave band was designed and simulated as an example. Then this lens antenna was measured by the planar-near-fields (PNF) method. Finally, the influence of the measurement probe was characterized also by the FDTD method and taken into account by the calibration. And it is found that the results of focal spot size obtained by the FDTD-PWS method are in good agreement with the experiment data by the probe compensation.
Computer vision scheme for autonomous landing of unmanned helicopter on ship deck
Wang Xiaojian, Pan Shunliang, Song Zishan, Shen Weiqun
2007, 33(06): 686-689.
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A computer vision solution based on landing mark for guiding an unmanned helicopter to the ship deck was studied. Factors which limited the pose estimation efficiency were analyzed and a novel information-blocking based image processing method was proposed. With the optional coordinate transformation the ideal region for image processing was obtained, and by applying the technique of line direction coarse identification, the line parameters scope was determined and the space need to be traversed in line hough transformation was narrowed. The computation of low layer image processing was reduced. Tests on real image show that the target detection and state estimations in a 768 576 pixel size image may be completed within 30ms. The state estimations are accurate to within 2cm in each axis of translation and 1.5° in each axis of rotation when the equivalent distance between the helicopter and the ship deck is about 10m,and the algorithm is effective for the control of unmanned helicopter autonomous landing on ship deck.
Path planning method of UAV based on CHC algorithm
Zhang Zhenli, Wang Yingxun
2007, 33(06): 690-693.
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An approach of UAV(unmanned aerial vehicle) path planning based on the improved genetic algorithm CHC(cross generation heterogeneous recombination cataclysmic mutation) algorithm was proposed. The initial population was produced by the searching algorithms containing heuristic information. The fitness function was the combination of distance and menace index. The select operating population was summation of current and previous one, for the operating population was big, the genetic diversity could be kept better. The single node crossover was used in cross operating, and the nearest two ones of two lines were choosen as the cross nodes. The mutate operating process was that two nodes were searched first, then the ratio of the two nodes′ linear distance to the two nodes′ real distance along the path was calculated. If the ratio was less than a fixed value then a new route between the two nodes was planned. Due to the restrict of the UAV′s capability, the algorithm can avoid blindness and can speed up the constringency. Simulation results show that the planning algorithm is faster than the basal genetic algorithms and meet the optimal requirements.
Effect of digital precision temperature control on FOG IMU performance
Ren Zhuoheng, Song Ningfang, Cui Jiatao
2007, 33(06): 694-697.
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Referring to the object of tactical FOG (fiber-optic gyro) IMU (inertial measurement unit), the relationship between the environmental temperature and its measurement accuracy was analyzed. An applied temperature control method was put forward to bate the interference of external temperature on IMU. It optimizes temperature control scheme and control algorithm, which are based on thermal analysis and simulation. And according to it, a digital temperature control system based on fuzzy PID(proportion integration differentiation) algorithm was designed for IMU. Influence to the precision of gyros and accelerometers when without temperature control and with temperature control was respectively studied. The results of experimentation indicate precision temperature control to ameliorate inertial parts′ thermal condition could favor to improve the performance of IMU.
Algorithm for spares optimization of system with multi-items with different life distributions
Long Jun, Kang Rui, Ma Lin, Cheng Hailong
2007, 33(06): 698-700.
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Focusing on the system with multi-items with different life distributions, the Monte Carlo simulation-marginal analysis based algorithm for spares optimization was presented. The Monte Carlo simulation was used in calculating spares supply performance. Based on the spares supply performance, the marginal analysis was introduced in identifying the optimum spares configuration. In the case of spares optimization of system with multi-items whose life respectively submit to exponential, normal and weibull distribution, the optimum spares list was acquired with mean supply down time being as spare supply performance measure and cost being as constraint. The algorithm was validated by comparison. The result shows the algorithm′s applicability in spares optimization of complex system.
Building model and simulation about heat of fiber optical gyroscope
Meng Zhaokui, Cui Jiatao, Du Xinzheng, Yuan Chunfeng
2007, 33(06): 701-704.
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Based on the mathematical discreteness of the heat state equation, a high precision FOG(fiber-optic gyroscope) thermal model was built as system angel. The building course of the system thermal model of the fiber-optic FOG was introduced, including of building structure geometry model, inner heat source model and fiber coil model which is sensitive to the heat. The method building model is not only applicable to this type of FOG, but also to other type whose structure and composition is analogous. The heat point distribution and temperature field distribution of the system was studied by steady state thermal simulation. The inner temperature change during the startup at 25.6℃, -40℃ and +60℃ was analyzed by instantaneous state simulation, and the validity of the model was approved by the experiments. At last, some significative conclusions were gained. And this work will advance the batch production of the high precision optical fiber gyroscope.
Analysis of coarseness of edges extracted from borescope images based on wavelet transform
Li Changyou, Ma Qishuang, Yao Hongyu
2007, 33(06): 705-708.
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To recognize whether there existed crack damages in the inner structure of aircraft engine based on the borescope images, a method (that was called coarseness factor) was presented to describe the coarseness of edge curves extracted from the borescope images. The method first decomposed an edge curve into the scale coefficients and wavelet coefficients using dynastic wavelet transform at all of the possible scales. For the coefficients of the wavelet transform, the logarithm entropy was presented to calculate the respective strength of the scale coefficients and wavelet coefficients. And the ratio of the logarithm entropies of the wavelet coefficients and ones of the scale coefficients was defined as coarseness factor. Using the coarseness factor to estimate the coarseness of a curve, the greater the coarseness factor is, the coarser the curve is. Experiments show that using the coarseness factor as recognition feature of borescope images, the crack damages of borescope images can be recognized successfully.
Design and simulation of integrated flight and propulsion control for post stall maneuvers
Yang Lingyu, Guo liang, Liu Jiarun, Shen Gongzhang
2007, 33(06): 709-713.
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Research on simulation and design of IFPC(integrated flight and propulsion control system ) of super angle of attack maneuver were done for an advanced vectored-thrust aircraft. A new structure of IFPC was put forward. An engine stability control system was designed to enhance engine stability at super angle. Moment requirements were calculated by rigid body inverse dynamic method, and the aerodynamic surfaces and thrust vector were allocated by the optimal control allocation and the saturation principle. Simulation results show that engine operates steadily, and thrust vector supplies extra moment, when the aerodynamic surfaces moment is not enough. The dynamic response of system is rapid, and tracking characteristic is well.
Micro-structural analysis of three dimensional braided composites with profiled section
Li Diansen, Lu Zixing, Xu Xiaoyan
2007, 33(06): 714-718.
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The fundamental theory of braiding process of three dimensional braided preform with profiled section was described. The movement rules of the carriers in the machine plane and the planar and spatial yarns paths were analyzed systematically based on the preform with square section. The unit models in the joint rectangle region of interior, surface, and corner of three dimensional braided composites with profiled section were established besides the unit model of interior, surface, and corner of three dimensional rectangular braided composites by means of a control volume method. The surface of these models is parallel to the surface of perform, which is suitable for the analysis of the mechanical properties. In addition, the math relationship between braiding parameters was deduced on the hypothesis of the yarns with the elliptical cross-section. It would be a solid base for the analysis of the properties of three dimensional braided composites with profiled section.
Trot gait and energy consumption simulation of a quadruped robot
Gao Feng, Lei Jingtao, Xu Guoyan
2007, 33(06): 719-722.
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Walking robot carries its own energy source such as battery to walk and finish exploring task, so the research of energy consumption is of great significance. The gait of walking robot has close relationship with energy consumption. Trot gait was adopted to analyze the relationship between energy consumption and relevant influence factors. The characteristics of trot gait and multi-loop serial and parallel mechanism were presented, and Denavit-Hartenberg coordinate method was adopted to express the kinematics equation and Lagrange dynamics equation of quadruped walking robot, then the virtual prototyping technology was used to establish the 3D simulation model considering contact between foots and ground, by which the energy consumption analysis of whole gait cycle and dynamic characteristics were calculated. By using the rate of energy consumption to evaluate energy efficiency of walking robot, the energy consumption during walking was analyzed with different walking stroke and different contact material,and the relationship between the rate of energy consumption and walking velocity was presented. The results can provide basis for the design of the physical prototyping.
Quantitative relationship between impact property and dynamic compressive performance of Ti alloy
Cui Dan, Zhang Zhengang, Wu Guoqing, Huang Zheng
2007, 33(06): 723-726.
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To explore the relationship between impact property and cold upsetting finished product ratio of Ti alloy,the effect of microstructure parameter on impact property of Ti-3Al-5Mo-4.5V alloy was investigated systemically with quantitative statistical analysis method. The relationship among crack initiation energy, crack propagation energy, total impact energy and the width of shear band was analyzed combined with the variety of the width of shear band after dynamic compressive deformation. The result shows as follows. First, as anneal temperature rises, α platelet ratio(length/width) increases first and then decreases, crack initiation energy ascends first and then descends, while crack propagation energy diminishes first and then increases, and total impact energy ascends persistently. Second, there is no certain relationship between total impact energy and dynamic compressive performance; crack initiation energy is in inverse proportion to the width of shear band, while there is a positive correlation between the crack propagation energy and the width of shear band linearly.
Algorithm combined analytical and numerical solutions for robot inverse kinematics
Liu Da, Wang Tianmiao
2007, 33(06): 727-730.
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Aiming at some robot configurations which can′t be resolved by analytical solution, an inverse kinematics algorithm, in which analytical and numerical solutions are combined, was proposed. This algorithm simplified the previous method to search a suitable object function, and then iteratively solved the one-dimensional joint variable, by which the other joint variables could be derived. The algorithm developed here performed a kinematics inversion of a 5 degree of freedom robot with no closed-form solutions in less than 3 ms using a desktop computer, an order of magnitude faster than the times found in the literature. This method is simple and fast enough to be suitable for real-time manipulator control. This approach does not require computation of the forward kinematics and can be used with manipulators of any geometry, although it is most efficient when applied to orthogonal manipulators.
Latitude distribution algorithm of cutter position optimization on drum-like cutter for strip-maximization
Li Zhengqiang, Chen Zhitong, Xiao Jun
2007, 33(06): 731-735.
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Based on the theory of the shortest lines, the drum-like cutter was dispersed along the latitude direction convenient for the cutter location and pasture regulation. For global fitting the curvature distribution of the cutter and the surface to be machined, cutter was firstly located to one point at the machining surface; the best contact point was searched in a certain range at the machining surface for the maximum bandwidth. The iso-parametric tool-path planning method and the iso-scallops tool-path planning method were used. A program was developed to verify the validity of the new algorithm in avoiding interference, realizing maximal path interval, achieving the iso-parametric tool-path planning method and the iso-scallops tool-path planning method. It is very important and can be widely used to promote the machining efficiency and the quality of the machining sculptured surface in navigation apparently.
Modeling of single track vehicle′s dynamics based on co-simulation
Zhang Hongbing, Ding Nenggen, Wang Hongchen
2007, 33(06): 736-738.
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To investigate the dynamic characteristics of single track vehicles, a driver-vehicle closed-loop co-simulation model was built. The model consists of two parts: a multi-body dynamic model built in Adams and a driver model built in Matlab based on the theory of ′single point preview optimal curvature model′. The paths for the slalom test and the lane change test were designed respectively according to ′Test procedure for vehicle′s handling and stability simulator′. Co-simulations with the driver-vehicle closed-loop co-simulation model were undertaken, and results show that it can well follow the paths. So its rationality could be validated. The co-simulation model built provides an effective measure for research of the dynamic characteristics of single track vehicles.
Key-feature-based clustering algorithm for search engine results
Zhang Hui, Xie Ke, Pang Bin, Wu Hui
2007, 33(06): 739-742.
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To solve the problem that users of web search engines are often forced to sift through the long ordered list of document, a new key-feature clustering (KFC) algorithm was presented to help locate the valuable search results that the users really needed, which was different from VSM. The algorithm firstly extracted some key features from the keywords in the search results. Then the relationships between key features were analyzed and features were clustered. Finally, the documents were clustered based on these clusters of key features. The algorithm was tested and validated by the results of experiments.
High performance round-robin arbiter for virtual channel router
Zhang Zhe, Gao Xiaopeng, Long Xiang
2007, 33(06): 743-747.
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Two typical virtual-channel router architectures were analyzed, whose switch fabrics were in different scales. The scale of switch fabric was indicated to lay great impact on scheduler and arbiters in the router. Two arbiter architectures were proposed as variations of PPE, a round-robin arbiter. By moving some steps on the critical paths to the non-critical paths and having some critical steps parallelized, the proposed variations shortened the critical paths over PPE to improve the performance. Some steps were adjusted, so that the side-effect on area caused by above modifications was eliminated. All arbiters including PPE and the proposed variations were evaluated in several scales, using TSMC 0.35μm CMOS technology. The results show that the proposed ones improve the performance by more than 12% and 17% over PPE respectively, and also have less area cost in most cases.
Electronic and optical properties of PbTiO3 cubic phase
Bai Yu, Chen Qiang
2007, 33(06): 748-751.
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Using FP-LAPW (full potential linear augment plane wave) method, the electronic band structure, DOS (density of states), and charge density contours of ferroelectric PbTiO3 bulk in cubic paraelectric phase were calculated with GGA (generalized gradient approximation) exchange correlation. Band structure calculations show that a directed band gap of 1.7eV at Χ point in the first Brillouin zone. The results from analyzing the DOS and charge density contours show that the bonding between Ti and O atom is covalent. The optical properties of PbTiO3 were also discussed according to the result of the electronic structure. The dielectric function, reflectivity, refractive index, extinction coefficient, absorption coefficient, and the energy loss spectrum were presented
Microscopic study of formation and mechanical properties of amorphous Cu
Wang Guanghai, Pan Hui, Ke Fujiu, Xia Mengfen, Bai Yilong
2007, 33(06): 752-756.
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The microscopic mechanism of the formation and mechanical behavior of amorphous Cu were studied by using molecular dynamics simulation method. The radial distribution function(RDF) and the pair analysis(PA) technique were used to characterize the structure of Cu during solidification. The splitting of the second peak of the RDF in amorphous state, is caused mainly by the increase of 2101, 2211, 2331 pairs. Simulations of tension and shear tests show that the deformation of the amorphous Cu is similar to that of crystalline metals. However, the microscopic mechanism of deformation of amorphous metal is different from that of crystals. In order to understand the microscopic mechanism, the statistical evolution of microscopic number density was analyzed. It was found that the evolution of microscopic density presents inhomogeneity, which may play an important role in the deformation.

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