Advanced Materials Research Vols. 989-994

Abstract: In cognitive radio networks (CRNs), improving the performance of SUs is the main aspect of present study. In this paper, we focus on the optimal access strategy to provide QoS guarantees for multi-services. The contribution of this paper is as follows. Firstly, we formulate and solve the optimal spectrum access problem with different channel reservation scheme. Secondly, we take account of buffer for handoff secondary users and propose a handoff scheme for multi-services. In addition, the computation complexity of solving the optimal channel reservation problem is simplified by a binary search. The system is analyzed using a continuous-time Markov chain model. The numerical results confirm the validity of the proposed scheme.

Abstract: Since the thermal imaging system detection ability and spatial resolution is lower than visible light CCD array,the definition of the infrared image is lower than that of the visible light image, which needs enhancement to improve image quality and for human vision. This paper proposes an enhancement algorithm of infrared images based on dual threshold of the exponential transform, firstly the original image can be processed by median filter to reduce noise,next separate the detail information of the 14-bit infrared image after noise reduction; then deal the detail image with the double threshold method based on the exponential transform,retaining or enhancing the detail information;when it comes to the base image,deal it with the gray linear mapping method, compressing its dynamic range.Finally the detail image and the base image are composed together after processing,getting 8-bit infrared image which can display and be processed on an ordinary display.

Abstract: In order to improve the quality of haze degraded image, a novel method is proposed combining dark channel prior and the atmospheric degradation model. Firstly, adaptive block is performed to acquire the dark channel image; then, in HSV space, laplacian pyramid filter is required to obtain the low pass portion of V, further compensated by the single scale Retinex to achieve the final atmospheric light; moreover, for the smoothness trait of guided filter and its fast operation rate, it is suggested to gain the optimal transmission map. Experimental results show that this algorithm can effectively improve the visibility of the optical imaging system.

Abstract: This research is conducted with the objective of improving the OFDM system in coal mines with regard to its defects and puts forward a structure diagram of STBC-OFDM transceiver for systems which require low complexity with a simulation of the system performance. Through the simulation, in which the STBC-OFDM communication system in coal mines is employed, the BER performance of the OFDM system is improved and the complexity and cost of the receiver is lowered with a significant reduction in daily maintenance.

Abstract: This paper presents a texture classification algorithm using Gabor wavelet and Gray Level Co-occurrence Matrix as feature extraction method and Support Vector Machine as classifier. Gabor transform and Gray Level Co-occurrence Matrix are used to get the features of the digital images, SVM classifiers are followed to build image and realize classification. The results of the experiments have shown that the methods described in this paper can improve the rate of correct classification effectively than traditional method of classification.

Abstract: Because the operational speed of the traditional image compression based on Mallat algorithm is slow, and auxiliary Storage space is occupied, image compressed method based on lifting wavelet transform is proposed, in order to realize its versatility, flexibility and high efficient. Experiments show that the lifting wavelet transform, is easy to realize integer wavelet transform can be used for lossless compression, and has higher compression ratio.

Abstract: Removed due to plagiarism The original research results can be found at http://www.sciencedirect.com/science/article/pii/S0968090X13000399

Abstract: In 1960 the first ruby laser came out , after 40 years’ development, laser engraving technology has been widely used in various areas. This paper describes the characteristics of laser engraving, the advantages and applications in industries and study images of laser engraving key technologies in-depth from image processing, laser engraving process parameters and clean carbide processing , and JK-2030 CO₂ laser engraving machines on paulownia color photos as examples for authentication, making laser engraving images more easily and efficiently .

Abstract: In order to improve the performance of PCM/FM signal demodulation system, this paper studies a kind of Symbol Detection more (Multi-Symbol Detection, MSD) technology. First for PCM/FM in hardware demodulation, a series of problems in the introduction of MSD software demodulation method; Then the MSD demodulation under low SNR synchronous implementation; The algorithm simulation, the results show that the bit error rate of 10^-4, detection performance than traditional non-coherent frequency discrimination algorithm can improve the nearly 3 dB, the performance is very ideal.

Abstract: PCM/FM system is one of the most widely used in the rocket telemetry system. Target spacecraft reentry telemetry telemetry signals in the process of low signal noise ratio (SNR), that the breakthrough tradition demodulation method of demodulation threshold problem, combined with the PCM/FM signal phase characteristic, the research based on a baseband complex rotating orthogonal symbol detection software (MSD) to solve method, and the corresponding synchronization algorithm is applied to ensure the smooth operation of the demodulation. The simulation and test results verified the soft demodulation algorithm can make the demodulation threshold effectively reduce.