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2012 Vol. 38, No. 11

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Accelerated hardware target labeling based on run-length accumulation
Zheng Hong, Li Jun
2012, (11): 1425-1429.
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To solve the problem that long time consuming and delay of target labeling algorithm seriously affected the effect and real-time performance of target tracking, fast accelerated hardware target labeling algorithm based on run-length accumulation was proposed. The pixels of image were converted to runs, and then the two runs of adjacent lines were accomplished accumulation calculation according to the defined accumulation rulers. The labeling conflicts were avoided. The algorithm could complete connected components labeling and calculate connected components features in a single pass without establishing equivalence table. Experiments show that the algorithm uses less memory resources with smaller result delay, and has higher speed ratio compared with software algorithms. So it can benefit to the fast and real-time processing of later target tracking.
Robust LPV control design using the gap metric
Zhang Zenghui, Yang Lingyu, Zhang Jing, Shen Gongzhang
2012, (11): 1430-1434,1439.
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A new robust linear parameter-varying (LPV) controller design method based on gap-metric was presented for the wide flight envelope and strong model parameters uncertainties of hypersonic vehicle. A new convex decomposition strategy with the optimal gap-metric was proposed. In order to reduce the conservativeness of the controller, self-scheduled LPV control was implemented using the new strategy. Vertex models of the polytopic LPV system were solved considering the model parameters uncertainties to improve the robustness of the controller nearby the vertex boundary. The new design approach was applied to the hypersonic vehicle. Simulation results show that this new method can reduce the conservativeness of traditional LPV controllers. The command tracking and robustness of the LPV control system are in satisfactory performances. The robust performance and stability of the system under strong parameters uncertainties are also guaranteed.
Application of routing algorithm in configuration optimization of LEO communication satellite constellation
Sun Yuanhui, Han Chao
2012, (11): 1435-1439.
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The special features of low earth orbit (LEO) communication constellation determine that costs, coverage and routing performance should be wholly taken into account in configuration optimization. In previous cases, the optimized configuration cannot meet the requirements well as routing performance was often ignored.Two evaluation indicators with clear meaning were proposed to signify routing performance and their necessities and effectiveness were proved in their simulation as objective functions. After that, the application of routing algorithm in configuration design was realized. According to the results comparison, in the premise that the configuration has little change, not only the basic requirements of costs and coverage are fulfilled, and also the routing performance of constellation is greatly improved when routing algorithm is added into configuration optimization. The best configuration design is obtained and some useful conclusions are showed finally.
Image distortion fast correction for image intensifier DR/CT system
Yang Min, He Xiaoyi, Wei Dongbo, Liang Lihong
2012, (11): 1440-1444.
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Starting from the distortion characteristics, correction precision and real time correction requirements for XRS-152/153 image intensifier DR/CT system, a cubic polynomial curve-fitting algorithm was proposed. Meanwhile, in order to solve its calculation complexity problem, graphic processing unit (GPU) was applied to make use of its high parallel and fast floating-point calculation abilities. In the implementation, the image was mapped to the GPU’s texture and multi-thread parallel calculation was adopted. The experimental results show that the correction algorithm could effectively restore the original information of the image. In addition, the acceleration with GPU could realize the real-time distortion correction without the loss of image information.
Modeling and verification of software safety requirement based on ontology
Li Zhen, Liu Bin, Miao Hong, Yin Yongfeng
2012, (11): 1445-1449.
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The catastrophic accidents are usually caused by and related to safety requirement and the manual review cannot meet the strict verification requirement of software safetyd.Consequently, the definition of software safety was discussed, the recognized and related standards with guidebooks were strictly selected as the knowledge bases of requirement verification, the ontology models were built by "seven step method", the rules were formally described by the concepts and relations in ontology models to support verification, the tool prototype of formal modeling and verification of software safety requirement was designed and realized, and the tool prototype was used to the comparative experiment between manual verification and automatic verification. The result of the experiment shows that using tool prototype is far better than manual verification in time consumed, verification times and the prototype has a good usability as well.
Ambiguity of rotating-element electric-field vector method and elimination method
Zhai Yu, Su Donglin
2012, (11): 1450-1453.
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Ambiguity of rotating-element electric-field vector (REV) method for calibration of phased array antenna and the elimination method were studied. Two sets of solutions exist for calibration of phased array antenna using the REV method. And one of sets is pseudo solution. Ambiguity and physical interpretation of solutions were studied by the theoretical analysis. In order to eliminate the ambiguity, a novel method was proposed by the variable substitution based on several tests with different phase distributions. Theoretical analysis and simulated results show that the proposed method can eliminate the ambiguity of the REV method effectively. Furthermore, this method has advantages of high operability and low requirement for test system.
Disturbance compensated terminal sliding mode control for hypersonic vehicles
Zeng Xianfa, Wang Xiaohu, Zhang Jing, Shen Gongzhang
2012, (11): 1454-1458.
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An attitude control approach for hypersonic vehicles based on disturbance compensated terminal sliding mode(TSM) was studied. First, a modified TSM surface which switched to high gain linear sliding mode surface while in the neighborhood of equilibrium point was proposed to overcome the singularity problem of traditional TSM, and maintain the high rate of convergence. Then the error convergence property of the proposed TSM in the presence of disturbances was analyzed theoretically. To improve the robustness and precision of TSM control, extended state observer(ESO) was designed to estimate and compensate for disturbances. Finally, 6-degree of freedom numerical simulation was carried out, and the simulation results demonstrate that the control performance and robustness are improved by the proposed method.
Disturbance observer based magnetically suspended reaction attitude flywheel motor control
Zhou Xinxiu, Fang Jiancheng, Liu Gang, Zhang Ran
2012, (11): 1459-1463,1468.
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As the existence of mass unbalance of magnetically suspended flywheel rotor, the precision of output torque/speed of flywheel would be influenced. In order to estimate the unbalance vibration, a nonlinear disturbance observer for time-variation harmonic disturbance was proposed. The dynamic response and steady-stage error regulating characteristics can be adjusted according to systematic requirement. A variable structure controller based on nonlinear disturbance observer was designed for speed control and vibration compensation. By improving the sliding mode function and sign function the chattering can be suppressed. The validity of the control method has been proved by simulation and experiment. The proposed controller is superior in the dynamic response performance, steady-stage error regulating characteristics and disturbance attenuation ability.
Dynamic plastic collapse mechanical model of honeycomb structures out-plane deformation
Fan Yanbin, Wang Zhili
2012, (11): 1464-1468.
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Based on the static plastic collapse stress (SPCS) theoretical model, a dynamic plastic collapse stress (DPCS) theoretical model of honeycomb structures under impact loading was built. In view of the effect that the strain rate had on the dynamic mechanical performance of honeycomb material, the relationship between SPCS and DPCS was established by using Cowper-Symonds model. A sheet bending theory based strain rate formula via the average impact speed was developed. Furthermore, a function about the relationship between DPCS and impact speed was proposed. At last, an out-plane deformation simulation of the aluminum honeycomb structures under impact loading was performed on LS-DYNA dynamics software. The numerical calculation results coincide with the theoretical model calculation ones.
Integrated navigation based on pulsars and sun observation including clock error correction
Yang Chengwei, Deng Xinping, Zheng Jianhua, Gao Dong
2012, (11): 1469-1473.
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In order to improve the accuracy of navigation and clock correction of a deep space probe during cruise phase, an integrated navigation method was advanced. By combining the X-ray pulsar based navigation(XPNAV) with the sun line-of-sight vector, and the radial velocity of the probe relative to the sun, an integrated navigation system was advanced by using information fusion, based on extended kalman filter(EKF). The state of atomic clock error was considered in the system model. The UD factorization algorithm was applied to control the rounding error. The simulation results demonstrate that this method can control the divergence rendered by the clock error in EKF. Compared with XPNAV, this method can provide a higher navigation precision and more effectively control the clock error.
Situ observations of structural transformation in TB5 titanium alloy during one way tensile test
Liu Changxu, Wu Guoqing, Sha Aixue, Wang Qingrui
2012, (11): 1474-1477.
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Microstructure transformation in Ti-15V-3Cr-3Sn-3Al(TB5) titanium alloy during one way tensile test was studied in situ observations of the video microscope. The results show that the change of the microstructure of the titanium alloy in uniaxial tension is not obvious in the elastic stage, but according to the change of the slip bands in the microstructure it can be divided into three stages following with the increase of the deformation in the plastic stage. The three stages are the single slip, the multiple slip and the cross slip.Geometric hardening occurs from the single slip to the multiple slip in uniaxial tension, so the change of the grains slows down and the rotation range of the slip bands is smaller.
Global stabilization of nonlinear systems via linear output feedback
Qu Weiran, Lin Yan, Zhang Xu
2012, (11): 1478-1482.
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The problem of global stabilization for a class of uncertain nonlinear systems using linear output feedback is considered. Instead of imposing triangular type restrictions on the nonlinear uncertainties, the existing linear output feedback control schemes were extended to certain nontriangular type restrictions. A linear high-gain observer and a coupled linear high-gain controller were constructed, and by using the gain scaling method, global stability of the closed loop system can be achieved. Simulation results are given to show the effectiveness of the proposed scheme.
Modification of SVM’s optimal hyperplane based on minimal mistake
Jiang Jueyi, He Yuzhu, Li Jianhong
2012, (11): 1483-1486.
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Since some value of error penalties C in C-support vector machine (C-SVM) may cause extreme and irrational optimal separating hyperplanes, a new modification of SVM’s optimal hyperplane was proposed. By modifying the distance restriction of separating hyperplane between positive and negative classes, the bias coefficient was calculated with minimal training samples’ total error, while the absolute value of the error difference between positive and negative classes was balanced considered, a better separating hyperplane with minimal mistake was obtained. The experimental results show that this algorithm has improved the classified precision and enhanced the ability of reducing the outliers and noises’ effect, compared to C-SVM and other modification algorithm.
Integrated reliability assessment for Weibull distribution using varied environment data
Hong Dongpao, Ma Xiaobing, Zhao Yu
2012, (11): 1487-1491.
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To improve the stability and accuracy of the reliability assessment, a method of integrated reliability assessment for Weibull distribution was proposed using the varied environment test data. In this method, the location parameter and scale parameter were assumed respectively as a function of relevant environment variables. Then the location parameter function was constructed by the method of radial basis function while the scale parameter function was constructed by the linear model. Thus the influences of environment factors on the reliability of the product were measured quantificationally. With the generalized linear model, the maximum likelihood estimations of the coefficients were obtained, and corresponding arithmetic was put forward. With the estimations, the approximated confidence interval for the reliability function was obtained according to the normal law. The instance analysis shows that this integrated reliability assessment method improves the precision of reliability assessment and is straightforward for engineering application.
GPS range error analysis based on navigation message representation
Wang Luxiao, Huang Zhigang, Zhao Yun
2012, (11): 1492-1496.
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Aiming at the new CNAV/CNAV-2 navigation message format in the GPS modernization process, the current GPS navigation message format and the new format in data expression were compared. To evaluate the navigation and positioning influence of different data truncated ways, the concept of truncation error was brought up to analysis the problem. The actual RINEX navigation data was utilized for generation, processing two message structures; range errors caused by ephemeris and clock parameters truncation were compared between NAV and CNAV/CNAV-2 message. Results show that CNAV/CNAV-2 range error caused by parameters truncation is smaller than NAV message. NAV message is more sensitive to truncation errors. Meanwhile, to CNAV/CNAV-2 message ephemeris parameters truncation can improve range error up to a centimeter level, clock parameters truncation can improve range error up to a decimeter level. Thus, clock representation accuracy should be improved with priority in limited bandwidth circumstance. More significant improvements of the accuracy can be achieved by adjusting the representation of the satellite clock parameters.
High precision control based on ADRC used in gimbal system of MSCMG
Xue Lijuan, Li Haitao, Li Hong, Xu Xiangbo
2012, (11): 1497-1501.
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Aiming at solving the problems that speed precision would be influenced by nonlinear friction and external random disturbance existing in magnetically suspended control moment gyroscope(MSCMG), a high-precision speed control method was proposed based on active disturbance rejection controller(ADRC). The load torque, nonlinear friction torque and the external disturbance torque of the gimbal system were compensated after they were estimated as the "total disturbance" by a third-order extended state observer. Simulation and experimental results show that the control method based on ADRC can improve the velocity precision and stability of the gimbal system by more than 50%, and has the characteristics of strong anti-interference ability and good dynamic behavior.
Robot object recognition based on learning and cognition with conceptual space
Liu Bingyao, Qin Shiyin
2012, (11): 1502-1506,1511.
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In view of the challenging issue for robot multi-class object recognition in complex environments with original feature space because those features can only embody some low level knowledge with poor discriminative performance, an approach to robot object recognition was presented based on conceptual space methodology. At first, the basic feature space was built through multi-sensor data fusion and feature extraction, thus gaussian mixture models (GMM) was employed to model objects properties in order to build conceptual space with characteristic of high level knowledge so as to learn the concepts of objects and improve their discriminative performance. Then support vector machine (SVM) was used to carry out multi-class object recognition for robot in indoor clutter environment. The experimental results demonstrate that the proposed method can not only represent the high level knowledge of objects, but also improve the performance of object recognition and environment perception of robot effectively.
Degaussing coils optimal calibration method based on multi-objectives
Zhu Xianqiao, Liu Daming, Yang Mingming
2012, (11): 1507-1511.
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The current method of ship degaussing coils optimal calibration has a shortage that it only takes the ship’s magnetic field crest value into account while pay less attention to its magnetic gradient crest value. Considering the current method’s shortage, a kind of calibration method with the purpose to reduce the crest value of both the magnetic field and gradient was proposed. Therefore, a multi-objective optimization model of the coils optimal calibration was built firstly with the coils’ equivalent currents as the optimized parameters and peak of both ship’s magnetic field and its gradient as optimized target. Then the Pareto solution set of the optimization problem was obtained by a kind of multi-objective particle swarm optimization (MOPSO). Last, the method’s effectiveness was verified by a certain example. The results show that the method can deal with both the magnetic field and gradient at the same time, and it can provide a set of different currents for the engineer’s choices.
Approach of determining accelerated degradation mechanism consistency’s boundary for accelerometers
Wang Qiancheng, Chen Yunxia, Deng Fengli, Kang Rui
2012, (11): 1512-1516.
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Through analyzing the Arrhenius model in the accelerated degradation testing, it is found that there is a close relationship between the operating stress and the slope of degraded trajectory in the accelerometer accelerated testing. The degradation trajectory models such as linear function, exponential function and power function were studied. The formulas on the operating stress and the slope of degraded trajectory were inferred from the perspective that the activation energy does not change. Then a method of determining accelerated degradation mechanism consistency’s boundary was offered based on the slope interval inspection of degradation trajectory. Finally, according to the constant temperature degradation simulation test data of the accelerometer scaling factor stability, the accurate temperature boundary that ensured the scaling factor stability degradation mechanism is consistent was given. The result proves that the method is feasible.
Method of multi-view modeling for 3D target based on SVDD
Ding Hao, Li Xudong, Zhao Huijie
2012, (11): 1517-1521.
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Popular 3D target recognition approaches based on image continue to struggle with challenge—viewpoint sensitivity. Multi-view modeling technique for 3D target offers promise for this challenge. A method of modeling 3D target based on support vector data description (SVDD) that could obtain a tight description covering most of the target feature data was proposed. Target’s images were captured with uniform grid on the viewing sphere and characterized by feature vectors. The support vectors representing characteristic views were obtained by applying SVDD to optimize the parameters of the minimal hyper-sphere which covers as many feature vectors as possible. The experiments were conducted by applying the proposed method to an image set (each target includes 2592 images) characterized by normalized moment invariants. The results show that the proposed method is effective and feasibility.
Analysis method for lunar landers landing safety
Su Qinghua, Zhao Yan
2012, (11): 1522-1526.
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In the lunar exploration program Ⅱ, the lunar lander to a safelanding site selection and realize safelanding is the key issues. Without considering engine control, attitude control and dynamic property, a high-definition landing territory was simulated on computer based on the low-definition data and known characteristic models of lunar surface. One times landing security can be obtained by computing and analyzing lander profiles and landing safety requirement. The landing safety possibility of this terrain can be obtained by computing many times landing only under the condition of same lander profiles. The landing territory, lander profile and safety parameters were simulated on computer by this method can be applied to both ground simulation experiments and real-timely analyzing possibility of landing safety during soft landing on the lunar surface.
Tractive performance analysis of diameter-variable wheel for 4WD all-terrain vehicle on soft soil
Chen Xinbo, Gao Feng, Xu Guoyan, Yao Xiaojiang
2012, (11): 1527-1531.
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Four-wheel drive all-terrain light exploration vehicle with diameter-variable wheels was innovatively designed out to solve the problems when conventional ground vehicles and wheels driving on soft terrain, such as poor trafficability, low efficiency, big energy consumption and even can-t drive. The wheel has two extreme working status: elastic extended walking-wheel and folded rigid wheel. Based on classical terramechanics theory, the dynamics models of interactions between two types of working wheel status and three kinds of typical soft soils were established. The drawbar pull, driving torque and driving efficiency as well as sinkage of diameter-variable wheel were analyzed under the condition of different slip. The results indicate that traction trafficability indexes are limited by wheel slip and soft soil parameters. The simulation provides theoretical basis for that the elastic extended wheel can improve significantly bigger drawbar pull, driving efficiency and soft soil traction trafficability, and reduce sinkage compared with that of rigid folded wheel’s, and can be used as the reference for further experimental investigation.
Improved Tour-Map graphical method for gravity-assist
Li Xiaoyu, Zheng Jianhua, Wu Xia
2012, (11): 1532-1536.
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The analysis of gravity-assist effects is of great importance on the design stage to specify both the swingby sequence and the initial parameters. An improved Tour-Map graphical method for this purpose was introduced, which permits a quick identification of key parameters in ballistic gravity-assist. By the patched conic assumption, the graphical method was developed according to the geometric relationship of excess velocity and the position and velocity of the gravity-assist planet, followed by analytical developments of key heliocentric orbit elements after swingby, such as period, inclination and eccentricity. Then the complicated requirements of gravity-assist was described as contours on two dimensional Tour-Map conveniently. A design example of high-inclination solar orbit with Jupiter assist was included to illustrate the usage.
Optimization of lunar soft landing trajectory based on combinational algorithm
Cao Tao, Dong Changhong
2012, (11): 1537-1541.
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Based on the Pontryagin’s maximal principle, the fuel optimal lunar soft landing problem can be simplified as a two point boundary value problem with variable final time. The initial adjoint variables were listed by searching the neighborhood of guessed adjoint variables with the employment of the combinational algorithm, which is combined with particle swarm optimization (PSO) for reducing the territory of searching region and simplex method (SM) for decreasing the time of obtaining suitable results. The most valuable advantage of the combinational algorithm is that both the globe searching and local searching are utilized at the same time. The simulation results show that the combinational algorithm used for designing the soft landing trajectory gives good performance on steady, efficiency and accuracy, even some practical constraints are under considered.
Vertical water entry cavity of cylinder body
He Chuntao, Wang Cong, Wei Yingjie, Ma Xiangfu
2012, (11): 1542-1546.
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Experimental studies of the vertical water-entry of cylinder bodies were conducted using high-speed camera to capture the splashes over the water surface and the subsurface cavity shapes. The cavities formation and stability were discussed for 140癱onical cylinder bodies fall into water freely. Experiment results show that the air cavity formed at very low entry speed, and lots of complicated flowing phenomena accompanied with the whole process of the formation, including splashes, cavity expand and cavity pinch-off. And the effects on the stability of the cavity due to the impact of tail were also discussed with vertical entry of the 140癱onical cylinder at an angle of attack, and the results reveal that the impacts on the cavity play different roles for stability of cavity at different stage of the whole process of formation. Finally, the effects on the cavity shapes and the pinch-off of vertical water-entry of right cylinder were conducted at various entry speeds. It shows that the cavity shapes and type of pinch-off are great depended on entry speed.
Improved HSSE-tree method based on binary label
Du Min, Feng Wenquan, Wang Dong, Zhao Qi
2012, (11): 1547-1551.
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Because of the increase of the demand for the autonomy of spacecrafts, model-based diagnosis has been a hot research spot both at home and abroad. Computing all minimal hitting sets is a key step of model-based diagnosis. An effectively improved method of HSSE-tree called Binary-label HSSE based on HSSE-tree and combining binary labels was put forward. The improved method used binary digits to mark the real elements of the nodes, and used effectively pruning and expanding strategies, to avoid the main problem of HSSE-tree, the explosive growth of the expanded nodes and supersets along with the dimension of the problems. Additionally, computing between binary digits can avoid the traverse of every element in a node when judging whether the node is a minimal hitting set (MHS), which also contributes to the significant decrease of the run time. Simulation results show the improved method costs much less space and time than the HSSE-tree method, which provides both theoretical and applicative foundation for fault diagnosis and Real-time diagnosis of spacecraft system.
Energy management strategy for composite energy storage for mobile robots
Lü Yingming, Yuan Haiwen, Cui Yong
2012, (11): 1552-1556.
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In order to enhance power performance of mobile robots and to extend service life of the energy storage without increasing in weight, the battery/supercapacitor composite energy storage was used instead of single battery. The performance of the composite energy storage is determined by the energy management strategy in large extent. The driving current of mobile robots often fluctuates in both low and high frequency range. So an energy management strategy based on both fuzzy control and filtering algorithm was studied. The fuzzy control algorithm determined how the low frequency profile of the driving current was shared between battery and supercapacitor in big time scale. And the filter algorithm decoupled the high frequency component, which was supplied by supercapacitor, from the driving current in small time scale. In the energy management system, the supercapacitor current was controlled via a Bi-DC/DC converter, so that the battery current was regulated indirectly. The effectiveness of the energy management strategy is proved by both the model simulation and the prototype experiment.
Fault diagnosis based on blind source separation using kernel function with finite support samples
Yang Yanlong, Cheng Wei, Chang Hongzhen
2012, (11): 1557-1561.
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It is important to extract fault features when machine would be in fault state. In order to separate different fault vibration signals from measured mixtures and diagnose the fault features of the machine effectively according to the separated signals, a blind source separation (BSS) method using kernel function based on finite support samples was proposed. The method is stronger adaptability for the score functions estimated according to finite support observed signal samples. The simulation results prove that the proposed BSS algorithm is able to separate hybrid mixtures that contain both sub-gaussian and super-gaussian sources. It is shown that the algorithm has better separation performance when compared with other BSS ones. The results of an experiment under the motor’s composite fault states with pedestal looseness fault and rotor unbalance fault show that this method is feasible for fault diagnosis.
Theoretical analysis of heat transfer in oscillating flows with fractional Maxwell model
Li Mingzhen, Dong Jinzhong
2012, (11): 1562-1566.
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By solving the momentum and energy equations of the oscillating flow with the fractional Maxwell model, which is driven by a sinusoidally varying pressure gradient, the general analytical solutions of the velocity profile, the temperature profile and the enhanced thermal diffusivity were obtained. Based upon the analysis of the enhanced thermal diffusivity, it is found that the parameters influenced the enhanced heat transfer for the problem are the Womersley number Wo, the Deborah number De, the dimensionless amplitude Δx/R and the Prandtl number of the fluid Pr. The heat transfer with fractional Maxwell model exhibits resonance phenomena similar to the flow of the viscoelastic fluid. And the number of the resonance peaks increases with the decrease of De, the frequency of the first peak decreases with the decrease of De. In addition, the frequencies where the resonance occurs are not concerned with the Pr and Δx/R.

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