A new practical free space quantum communication system is proposed, it is based on the principle of quantum secure
direct communication. Quantum cryptography is a practical method to realize free space optical communication.
Different from the existing free space quantum key distribution communication system, the free space quantum secure
direct communication is deterministic and the system is more simple. In this paper, a new structure of four transmitting
channels is prensented, this structure could increase the security and capacity of system. The setup of transmitter and
receiver of each transmitting channel is discussed in detail, and the communication process is analyzed. The result shows
that this free space quantum system could be realized and can work over long distance.
In this paper, a novel VLC method based on 2nd-run-level coding and dynamic truncation is proposed to compress the DCT coefficients efficiently. In the proposed VLC, 2nd-run-level is first employed, following the traditional run-level coding, to further reduce the considerable redundancy existing in the original level and run sequences. In order to achieve a higher degree of context adaptability and coding efficiency, dynamic truncation is introduced and employed in the sequential coding of 2D symbols without large amounts of 2D-VLC tables required, though adding extra coding complexity to some extent. Adaptive EG/GR selection is also presented and recommended since it brings extra improvement in compression efficiency without increasing any computational complexity. Experimental results show that when compared with context-based 2D-VLC, the proposed VLC method gains 0.25 dB ~0.79 dB in PSNR and achieves 5.30% ~ 11.58% improvement in bit rate reduction.
The sensitivity of channel bit error rate (BER) to the turbo coding parameters (i.e., code rate, iterative number and interleave length, etc) and the wireless channel statistic enlightens us to model a BER for turbo coding over Rayleigh channel. The model presented in this paper synthetically considers and quantificationally analyzes the impacts of all the coding parameters and the wireless channel statistic on the BER, and then emphasizes a simple equation that relates the BER at the encoder to the relevant coding parameters. Based on this model, the BER performance can be estimated even before channel coding given certain coding parameters set and channel statistic. The simulation results show that the model can handle the actual values with high accuracy. The maximal average predictive error is around 0.07%. Moreover, the proposed model is very regular and simple, and can be extended to other cases. These characteristics will make it more useful in practice.
Through analyzing the different relative depth of a 3D surface between the artificial target and the natural scene, a novel method of target detection based on wavelet transformation and geometric characteristics of 3D surfaces' texture is prosed. The wavelet Holder constant, which denote the relative distance between camera and targets, are calculated in a series of different multi-resolution images, and the targets are detected by calculating the slope of beeline. The target, which cannot be detected using groovy fractal Hurst exponents, can be detected perfectly using this method. The results show this method can improve the capability of anti-disturbance, provide accurate estimation and is also suitable for identifying specific targets in a complex background.
Based on the model of fuzzy function and the distance from objects to lens, a new 3D adaptive stratified filtering of volume image is developed. The volume image is split into several non-intersected sub-level volume images along the z- axis, each sub-level volume image is regard as a 2D image, and processed by 2D filtering. The problems of boundary division and anti-alias are also solved through introducing alpha value. The efficiency of stratified filtering is also improved, and the error of stratified filtering is less than given a constant P. The experimental results show that this is an effective method.
Metamorphosis or morphing is the process of continuously transforming one object into another, and is popular in computer animation, industrial design, and growth simulation. In this paper, a novel metamorphosis approach is presented for computing continuous shape transformation between polyhedral objects. Metamorphosis can be achieved by decomposing two objects into sets of individual convex sub- objects respectively and constructing the mapping relationship of subsets, this method can solve the metamorphosis problem of two non-homotopic objects (including concave objects and holey objects). The results of object metamorphosis are also discussed in this paper. The experiments show that this method can generate natural, high quality metamorphosis results with simple computation. This method can also be used in font composition and interpolation between two keyframes in 2D and 3D computer animation automatically.
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