The unsteady flow around a triangle cylinder was simulated using a modified Gao-Yong turbulence model based on the unilateral statistical average method. The numerical method used in this simulation is an unstructured staggered mesh scheme. The computational results show that the modified Gao-Yong turbulence model can successfully simulate vortex shedding characteristics. The Strouhal number and time-averaged velocity profiles also agree better with experiments than that of the original Gao-Yong turbulence model.
The near-field MMW synthetic aperture imaging radiometer is very excellent imaging system for obtaining high resolution images. The corresponding imaging algorithms are usually established based on the conventional FFT with the uniform sampling of visibility function. But a lot of irregular antenna arrays appeared for some reason, such as the coordinate perturbation and the development of the synthetic aperture imaging system. And the visibility functions of these arrays are always random. The un-Cartesian sampling data are not distributed on the uniform grid points. For this random distribution of visibility function, the traditional FFT based on the uniform Cartesian sampling cannot image well. Thus we adopt NUFFT to reconstruct the images from the non-uniform visibility function samples in this paper. Based on the near-field imaging formulas, the accurate system functions are established in NUFFT algorithm. The effectiveness of the NUFFT is tested by the corresponding simulation experiments with 1D and 2D Target scenes. The results show that the NUFFT is an effective imaging algorithm for near-field MMW synthetic aperture imaging radiometer with arbitrary distribution of the visibility function.
An electric power dedicated broadband wireless network traffic load capacity test and evaluation method is designed, which will be used for the performance test and evaluation of grid wireless communication network. This method can be used in the actual broadband wireless communication network, to count and analyze the data goodhput, delay, packet loss rate, and retransmission rate performance of power business in the broadband wireless communication network. The capacity performance of broadband wireless communication system can be evaluated, then it can judge whether the wireless communication system can meet the requirements of power business data communications.
In the actual satellite positioning and navigation system, multi-path effects not only cause distortion of the pseudo-random codes and navigation messages, but also cause the carrier phase distortion. For the problem of acquisition of BOC signals spreading in the multipath fading channel, a comparison between acquisition performances of different channels is implemented by means of building models of different channels. The reflection that multipath fading channel effects on acquisition of binary offset carrier (BOC) modulated signals is analysed, combining with Rice factor K and multipath routing number L. Theoretical analysis and simulation results show that, the larger Rice Factor K is, the larger value of main peak of acquisition function can be, the better acquisition performances can be. The smaller number of channel path, the less emergence of side peaks can be, the better acquisition performances can be.
Metadata integration is an important issue in metadata management. It presents a metadata integration strategy based on SOA architecture for data warehouses. In this strategy, Web Service is adopted as application frame; Metadata is modeled by CWM and metadata encapsulation is designed in XML. The metadata from distributed data warehouses has been efficiently integrated and reused. It focuses on the architecture of the system, the structure design of CWM, as well as various Web Service methods creation and call. Finally, verify the feasibility, effectiveness and practicability of this solution by experiment.
Based on the needs of current avionics system fault diagnosis and health management on engineering project, this paper designed a program for fault diagnosis of typical avionics system module based on artificial intelligence. The basic principle of information-enhanced BIT was discussed. Then a fuzzy nature network designed for fault was built which combined self-adaption function. Beside software and hardware diagnosis overall framework is included. This paper provided a strong support for improving the ability of fault diagnosis of avionics products, reducing false alarms.
This paper presents a new intuitionistic fuzzy c-means (IFCM)clustering algorithm by adapting a new method to calculate the hesitation degree of data point in cluster. From the definition of fuzzy entropy, if a clustering result of a data point has bigger fuzzy entropy, the clustering result should have more uncertainty. It means that we have insufficient information to deal with the clustering of a data point, so the hesitation degree of clustering result of the data point should be greater. Form this opinion, a mathematical model is applied to calculate the hesitation degree of clustering of data point based on fuzzy entropy is given. An IFCM clustering algorithms is present. Experiments are performed using two-dimensional synthetic data-sets referred from previous papers. Results have shown that proposed algorithm is not only effective for linear and nonlinear separation, but also able to describe more information comparing to fuzzy c-means clustering algorithm.
Screen coding is a new spatial domain information hiding technique, long recognition time and low recognition rate belongs to the traditional methods. Mathematical morphology algorithm has a natural parallel implementation structure. It can be applied to simplify the image data , keep the shape feature and remove the irrelevant part. In this paper, mathematical morphology algorithm is use to image denoising and edge extraction. By use of dilation operation, the influence introduced by tiny deformation is released. Experimental results indicate that this new algorithm have a higher recognition rate and it can reduce the decoding time .
This dissertation introduces the basic software and hardware structures, function and features of an AC contactor dynamic characteristics testing system. This system uses a laser displacement sensor to measure core displacement and uses PVDF contact pressure sensors to measure the dynamic contacts contact pressure. This system can not only test the AC contactor dynamic characteristics like the core displacement, contact bounce, excitation voltage and exciting current signal, but the dynamic contacts contact pressure. Previous AC contactor dynamic characteristics test system does not have this function. Using this system, a distinct dynamic behavior of contact pressure was got from a dynamic testing of contact pressure on CJ20-25. The dynamic signal of core displacement contacts contact pressure, coil excitation voltage and exciting current and contact bounce can be obtained with the system, which lays a foundation to further perfection of modern design theory and application of electrical equipment.
In the existing anonymous privacy protection technology, there is a shortage of personalized privacy protection support for sensitive attributes before data publishing and sharing. In order to achieve more reasonable personalized privacy preservation and improve the precision of privacy preservation, this paper reviewed the latest researches in granular computing theory, rough set theory and k-anonymity theory, and presented a novel algorithm of personalized-granular k-anonymity based on the personalized decision degree of privacy preservation, in view of different personalized granularity decision selectivity of privacy preservation in E-business. It has been experimentally proved that the novel algorithm can achieve privacy preservation with more reasonable personalization, and its accuracy of privacy preservation is superior to p-sensitive k-anonymity algorithm.
In this paper we introduce a method to extract foreground from an image or a video and blend it into another environment. We analyze the weakness of previous algorithms, and propose a new method to improve the automaticity of the algorithm and reduce interactions with users. Self-adaption threshold and segmentation technique are used to preprocess the images or frames. And then we use the image matting and illustration technique to refine the segmentation results. Our method is also suitable for video editing to reduce the users operation. The experiment demonstrates that our algorithm can be used under several challenging scenarios.
The paper proposed a 3-DoF bicycle model, that considering the longitudinal acceleration or deceleration motion, the lateral motion and the yaw motion of the vehicle. A simplified piecewise tire model is proposed to improve the precise of the tire force. The bicycle model uses the wheel rolling speed information from the real car that is usually used in the ABS or other active safety devices. The simulation results show that compared with the 14-DoF full car model, the proposed bicycle model is good and can be used for the chassis control.
In this paper we propose a theory of matching markets approach to get the access opportunity for the unauthorized users who want to share a set of channels. Matching game of spectrum allocation which can be used in cognitive radio relay system is advocated. First, in matching game algorithm, the selection of relay is abstracted to matching market problem. Then, access opportunity can be assigned by the deferred acceptance algorithm. The algorithm balance interest among relay users and encourage them to do more contributions in order to be in exchange for more spectrum resource efficiently. The proposed scheme can reduce the termination probability and the blocking probability for heterogeneous calls, simultaneously. The results of simulation show that the proposed scheme can effectively improve the access performance of secondary users.
An exact analytic solution for the two-dimensional (2-D) point target spectrum is usually difficult to obtain because of the existence of a double-square-root term in the multiple receiver synthetic aperture sonar (SAS) range equation. Unlike monostatic SAS, multiple receiver SAS data are more challenging to process because the “Stop-and-Hop” isn't work. This paper discusses multiple receiver synthetic aperture sonar (SAS) processing using the extended Range Doppler Algorithm. One key step is to use an analytic form of the signal 2-D frequency spectrum derived by the method of series reversion, which can fully consider the space variant in azimuth direction. The other key step is to use a method of azimuth spectrum extension to solve the problem of azimuth undersampling and spectrum coupling. Besides, considered the coherence in the different sub-receiver, multiple receiver SAS data is to process based on data fusion. Simulations have shown that the extended RD algorithm can handle data with more complicated multiple receiver SAS than the previous algorithm.
Typical simulator system is composed of computer system, platform system, visual system and circuit control system, etc. of which the problem of fault detection of circuit control system is the key and the most difficult. This paper will make use of the advantage of ant colony algorithm in solving graph coloring to transform problem of incidence matrices division of digital circuits to graph coloring. At the same time, with genetic algorithm, this paper accelerates algorithm converging rate; with pheromone threshold value, this paper also optimizes convergence result mutation to some degree. After contrasting with experiments of other algorithms, feasibility and high efficiency of modified ant colony algorithm which is put forward in this paper has been proved.
This paper presents a novel method to inhibit the commutation torque ripple in a brushless dc motor based on the analysis of equivalent voltage coefficient. The equivalent voltage coefficient is analyzed at low speed with PWM in incoming phase and at high speed with PWM in outgoing phase separately. By setting the equivalent voltage coefficient in commutation period to the conduction period, commutation torque ripple is significantly reduced. Simulation and experimental results show the validity of this control technique.
CFG (Control Flow Graph) is the cornerstone of reverse analysis, and how to determine the targets of indirect jumps is a challenge for CFG reconstruction. Based on BRIL (Binary Reverse Intermediate Language) and standard abstract interpretation framework, a K-set abstract domain based on abstract memory model was adopted. Control flow and data flow analysis could be executed on this abstract domain simultaneously and iteratively until a fix point was reached. Experimental evidence shows that the precision degree and the time cost are changing with the value of K. As long as K is set appropriately, the CFG reconstruction algorithm can resume accurate CFG in a moderate costs, and the average false positive rate of indirect jump destination address is less than one (<;1).
In order to acquire better mine monitoring results, we established a monitoring system of hydraulic support movement state. The system used sensors and data acquisition modules, and was combined with virtual reality software Virtools. The communication between Virtools and data acquisition modules is achieved through the Software Development Kit (SDK) of Virtools and the Application Program Interface (API) of data acquisition module. Through integrating the 3D hydraulic support model into Virtools, and simultaneously transmitting the actual hydraulic support motion parameters to Virtools, the monitoring of the movement state of hydraulic support is enabled. And the monitoring result is far more better than previous monitoring systems.
To solve the problem of PRI jitter signal sorting, this paper presents a signal sorting method based on the cumulative square sine wave interpolating algorithm. The TOA of pulse were cumulative interpolated by the square sine wave. The method estimates the center value of the jitter signal PRI using fast Fourier transform in the frequency domain. Simulation results show that the algorithm can quickly and accurately sorting PRI jitter signal.
Dynamic matrix control (for short DMC) algorithm is presented based on Elman neural network (for short ENN), because the ENN can character the dynamic nonlinear system. The basic idea is to predict the system further output by ENN, and to estimate the system dynamic matrix, and then to carry out the dynamic matrix control algorithm. The method can control the nonlinear dynamic system and break through the limitation of mathematical model. The simulation shows that the ENN has good prediction ability and the proposed method is effective.
