Applied Mechanics and Materials Vols. 543-547

Abstract: In the FFT harmonic detection, the detection accuracy is reduced because of asynchronicity between the sampling frequency and the signal of base wave frequency. In order to improve the detection accuracy, a harmonic detection algorithm based on the fundamental frequency tracking is proposed. Firstly windowed interpolation FFT algorithm is used to detect signal of base wave frequency, then the fundamental frequency is tracked and the sampling frequency is dynamically adjusted. Finally, the signal sequence is obtained by quasi synchronous sampling with frequency multiplication technology, and amplitudes and phases of the signal are received with the FFT analysis. Because the sampling frequency synchronization error and the influence of frequency spectrum leakage are reduced, the detection accuracy is improved. This algorithm is applied to the electrical energy harmonic analysis with simple implementation and high accuracy.

Abstract: The RL(Richardson-Lucy) algorithm is an important method for restoration of turbulence-degraded images. However, the shortcoming of this method is that it tends to amplify the noise and exsits excessive smoothing in the iterative procedure. This paper discusses the RL algorithm and its improving methods focusing on turbulence-degraded images restoration.Firstly, a short exposure atmospheric turbulence-degraded model is established and a numerical computing method is proposed for random phase screen. Secondly, the essential principle and computational formula are deduced. To restore the object image effectively from the turbulence-degraded image, a new double-circulation iterative Richardson-Lucy restoration algorithm using TV-regularized method is proposed. This new algorithm introduces the total variation restraint and estimates the object image and the point spread function based on the inner and outer double-circulation iteration, which can use the inherent relation between the object image and the point spread function adequately. Simulation experiments show that the proposed algorithm can effectively preserve the details and edges of the image and its restoration effect is obviously better than the traditional RL algorithm.

Abstract: In traditional secret image sharing schemes, participants have the same status and shadow images are of approximately equal importance, which cannot satisfy some special requirements in the real situation. In this paper, we consider the problem of secret image sharing with the weighted threshold access structure, which means different participants can have different status and significance. Under the circumstance, each shadow image has one weight, and the secret image can be losslessly reconstructed, if and only if the sum of all shadow images weights is no less than the given weight threshold. In our scheme, we first construct the weighted threshold access structure of shadow images using the weighted threshold secret sharing scheme. Then, we employ the quantization operation to embed the secret image information into a host image to generate shadow images with different weights. In the retrieving procedure, a set of shadow images satisfying the weighted threshold can be utilized to restore the distortion-free secret image.

Abstract: A new method based on fractional correlation theory for estimating the Doppler and multipath time delay of the wideband echoes for LFM pulse radar by only one pulse signal is presented. First, the Doppler is estimated by energy cumulation of multipath component based on fractional correlation transform. Then, an order-reduced signal is reconstructed combining the Doppler with the prior knowledge of the transmitted signal, and the echoes signal is converted to many single-frequency signals. Finally, the multipath time delay is obtained by the dechirping method. The method is adapted for low SNR noise, can restrain the affection of the cross-items, and has a high time-delay estimation resolution. Some computer simulations are given in this paper and the results show that the new method is valid.

Abstract: Wireless Sensor Networks (WSNs) allows users to accurately monitor a environment by intelligently combining the data from the distributed nodes. A cluster-based network topology can increase the scalability and lifetime, the cluster head gathering the data and transmitting them to Sink with single hop or multi-hop communication. In this paper, the energy consumption model for clustering networks were analyzed and an adaptive energy-efficient routing approach was given, then the hop mode selection condition was analyzed and simulated.

Abstract: High resolution range profile (HRRP) got by discrete Fourier transform has fence effect, which will cause HRRP change with the range shift, and the HRRP features will also appear different even in the same perspective. To solve this problem, the paper proposed the echo product spectrum feature (REPSF), which has no fence effect and eliminates the influnce of random initial phase and range shift. The proposed feature makes full use of the amplitude and phase information of echo signal, and has super-resolution target identification ability. Finally, simulation results verify the correctness of the theory.

Abstract: Space-time adaptive processing (STAP) can obtain excellent clutter suppression performance based on the accurate estimate of clutter plus noise covariance matrix which is obtained by enough identical independent distributed samples. However, the short-range clutter of non-side looking airborne radar (non-SLAR) occurs range dependence. As a result, the clutter plus noise covariance matrix can not be estimated accurately and thus the clutter suppressing performance by STAP declines greatly. In this paper, an elevation constraint adaptive processing method is proposed. This method obtains the elevation target steering vector by the eigen-decomposition of the elevation covariance matrix on the ambiguous pure far-range clutter, it is used to suppress short-range clutter and the residual range-independent clutter can be suppressed by two-dimensional azimuth-Doppler STAP methods. Simulation results show validity of the proposed method.

Abstract: In this paper we introduce cross tree and block mathematical principles into the design of database system, divide the time sequence and storage space of computer database system, establish the mathematical model and algorithm of computer resources database system, and design the test database system. In this paper, we use high performance interface of Display Port, by way of coupling to communicate on two port control, and use RHEL 6.2 Linux virtual machine to do simulation experiment on process of database system. Through the simulation we find the API which is called by Read, Close, Mmap, Stat, Fstat is similar. It is consistent with the actual situation, and verifies the reliability of the program. Finally, we apply the database system to the network database construction of sports literature resources in the new town of Poyang Lake area. It reaches the effect that sport resources are shared by all. It provides technical support for the application of computer database system.

Abstract: According to the ternary number data mining algorithm, this paper combines SQL program operation and Oracle 10 g database system together. And then, numerical modeling and meshing technique are adopted to abstract data parameter from the database system. In addition,a mathematical model is established to abstract information from the ternary number database and the information literacy algorithm is also designed. In order to verify the reliability of the mathematical model and algorithm, a database abstracting numerical simulation experiment is designed for the velocity and temperature parameter. Through the experiment, it is discovered that there does not exist residual shock in the ternary number method when the data is being abstracted, which has a relatively stable convergence. At the same time, this paper gains the speed data distribution vector diagram. Eventually, the reliability of the algorithm designed in this paper is verified by comparing temperature data and the experimental data.

Abstract: The popularity of internet technology has brought the change very big to the life and production of modern humans, the current Internet technology application has penetrated into people in every aspect of modern life, has become an indispensable part of people's life. Firstly, system model of the current network communication to dissect, analyzes the architecture of network communication system, modulation and demodulation principle is applied to design the FM communication signal modulation system network communication in the Internet technology, the non coherent demodulation method to build FM demodulation system, realize the demodulation process through differential device, the anti noise performance of the method of frequency modulation system of MATLAB simulation experiments, the experimental results show that the method of anti noise performance significantly, to a certain extent, provide theoretical basis and technical support for the research in this field.