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Efficient shape modeling:: ε-entropy, adaptive coding, and boundary curves -vs- blum's medial axis

INTERNATIONAL JOURNAL OF COMPUTER VISION 2007年第2期74卷 183-199页

作者： Leonard, Kathryn CALTECH Dept Appl & Computat Math Pasadena CA 91125 USA

We propose efficiency of representation as a criterion for evaluating shape models, then apply this criterion to compare the boundary curve representation with the medial axis. We estimate the epsilon-entropy of two compact classes of curves. We then construct two adaptive encodings for non-compact classes of shapes, one using the boundary curve and the other using the medial axis, and determine precise conditions for when the medial axis is more efficient. Finally, we apply our results to databases of naturally occurring shapes, determining whether the boundary or medial axis is more efficient. Along the way we construct explicit near-optimal boundary-based approximations for compact classes of shapes, construct an explicit compression scheme for non-compact classes of shapes based on the medial axis, and derive some new results about the medial axis.

关键词： epsilon-entropy adaptive coding shape modeling medial axis boundary curve shape space

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adaptive COMPRESSED SENSING - A NEW CLASS OF SELF-ORGANIZING coding MODELS FOR NEUROSCIENCE

ADAPTIVE COMPRESSED SENSING - A NEW CLASS OF SELF-ORGANIZING...

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2010 IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： Coulter, William K. Hillar, Christopher J. Isley, Guy Sommer, Friedrich T. Univ Calif Berkeley 156 Stanley HallMC 3220 Berkeley CA 94720 USA Math Sci Res Inst Berkeley CA 94120 USA

ISBN: (纸本)9781424442966

Sparse coding networks, which utilize unsupervised learning to maximize coding efficiency, have successfully reproduced response properties found in primary visual cortex [1]. However, conventional sparse coding models require that the coding circuit can fully sample the sensory data in a one-to-one fashion, a requirement not supported by experimental data from the thalamo-cortical projection. To relieve these strict wiring requirements, we propose a sparse coding network constructed by introducing synaptic learning in the framework of compressed sensing. We demonstrate a new model that evolves biologically realistic, spatially smooth receptive fields despite the fact that the feedforward connectivity subsamples the input and thus the learning must rely on an impoverished and distorted account of the original visual data. Further, we demonstrate that the model could form a general scheme of cortical communication: it can form meaningful representations in a secondary sensory area, which receives input from the primary sensory area through a "compressing" cortico-cortical projection. Finally, we prove that our model belongs to a new class of sparse coding algorithms in which recurrent connections are essential in forming the spatial receptive fields.

关键词： adaptive coding biological system modeling random codes image coding nonlinear circuits

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adaptive COMPRESSED SENSING - A NEW CLASS OF SELF-ORGANIZING coding MODELS FOR NEUROSCIENCE

ADAPTIVE COMPRESSED SENSING - A NEW CLASS OF SELF-ORGANIZING...

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IEEE International Conference on Acoustics, Speech, and Signal Processing

作者： William K. Coulter Christopher J. Hillar Guy Isley Friedrich T. Sommer University of California Berkeley 156 Stanley Hall MC 3220 Berkeley CA 94720-3220 Mathematical Sciences Research Institute 17 Gauss Way Berkeley CA 94120

ISBN: (纸本)9781424442959

关键词： adaptive coding biological system modeling random codes image coding nonlinear circuits Biological system modeling random codes adaptive coding Nonlinear circuits image coding Neurosciences Sparse coding Neurophysiology COMPRESSED

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Delivery of triple-play services over broadband satellite networks

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IET COMMUNICATIONS 2010年第13期4卷 1544-1555页

作者： Fairhurst, G. Sathiaseelan, A. Baudoin, C. Callejo, E. Univ Aberdeen Sch Engn Aberdeen Scotland

Digital video broadcast return channel via satellite system (RCS) is a key European standard that specifies a broadband satellite system using dynamic capacity assignment and multi-frequency time-division multiple access. This study introduces new architectural components for an RCS system to support advanced Internet protocol (IP)-oriented multimedia. This will allow closer integration of satellite networks with the next generation of multimedia-enabled networks enabling operators to offer triple-play services that simultaneously support voice over IP, television-over IP and other services. These types of services are particularly suited to next generation satellite systems that combine transparent and multi-spot beam satellites with on-board regenerative signal processing, and can evolve to use adaptive coding and modulation.

关键词： Internet Protocol Television Satellite systems broadband Obstetric Delivery reactor cooling system signal processing adaptive coding SATELLITE NETWORKS Legal Services Treble

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A New Image Compression Scheme Based on Locally adaptive coding

A New Image Compression Scheme Based on Locally Adaptive Cod...

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IEEE International Symposium on Multimedia

作者： Chin-Chen Chang Yung-Chen Chou Chia-Chen Lin Department of Computer Science and Information Engineering National Chung Cheng University Chiayi Taiwan Department of Information Engineering and Computer Science Feng Chia University FCU Taichung Taiwan Department of Computer Science and Information Management Providence University Taichung Taiwan

ISBN: (纸本)9780769530581;0769530583

Vector quantization (VQ) is a simple and widely used compression technology in many applications. For image compression, VQ provides both a fixed compression ratio and maintains acceptable distortion. However, the performance of VQ still can be improved in terms of the image quality of compressed images and codebook size used for encoding and decoding. In this paper, a new VQ-like image compression method is proposed to improve the performance of traditional VQ by using locally adaptive coding concept. The experimental results confirm that the image quality of the compressed image offered by the proposed method is higher than 30 dB on average, and the number of codewords used in our codebook is less than that required by traditional VQ.

关键词： Image coding adaptive coding Image quality Vector quantization Computer science Application software Frequency domain analysis Clustering algorithms Pixel Histograms

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An adaptive coding Technique For PAPR Reduction

An Adaptive Coding Technique For PAPR Reduction

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IEEE GLOBECOM 2007 - IEEE Global Telecommunications Conference

作者： Zafar Q. Taha Xian Liu Department of Systems Engineering University of Arkansas Little Rock Little Rock AR USA

In this work, we present an adaptive technique to reduce high peak-to-average power ratio in coded orthogonal frequency division multiplexing. High peak-to-average power ratio has been a primary hurdle for the use of orthogonal frequency division multiplexing in low cost applications. Our coding approach for reduction of peak-to-average power ratio combines the error correction capability of the channel encoder and achieves peak-to-average power ratio reduction in the OFDM system. Our technique is easily implemented in terms of encoding as well as decoding. We develop analytical analysis of the maximum peak-to-average power ratio reduction achievable by this method. We consider the effect on bit error rate based on general analysis of antipodal signals.

关键词： adaptive coding Peak to average power ratio Decoding Error correction codes WiMAX Digital modulation OFDM modulation Power engineering and energy Systems engineering and theory Costs

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A Bit-level Text Compression Scheme Based on the ACW Algorithm

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International Journal of Automation and computing 2010年第1期7卷 123-131页

作者： Hussein Al-Bahadili Shakir M. Hussain Arab Academy for Banking and Financial Sciences Faculty of Information Technology Petra University

This paper presents a description and performance evaluation of a new bit-level, lossless, adaptive, and asymmetric data compression scheme that is based on the adaptive character wordlength （ACW（n）） algorithm. The proposed scheme enhances the compression ratio of the ACW（n） algorithm by dividing the binary sequence into a number of subsequences （s）, each of them satisfying the condition that the number of decimal values （d） of the n-bit length characters is equal to or less than 256. Therefore, the new scheme is referred to as ACW（n, s）, where n is the adaptive character wordlength and s is the number of subsequences. The new scheme was used to compress a number of text files from standard corpora. The obtained results demonstrate that the ACW（n, s） scheme achieves higher compression ratio than many widely used compression algorithms and it achieves a competitive performance compared to state-of-the-art compression tools.

关键词： Data compression bit-level text compression ACW（n） algorithm Huffman coding adaptive coding

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adaptive modulation and coding for MIMO systems with V-BLAST detection

Adaptive modulation and coding for MIMO systems with V-BLAST...

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66th IEEE Vehicular Technology Conference

作者： Lu, Guoquan Li, Baojin Wang, He Song, Yang Yang, Dacheng Beijing Univ Posts & Telecommun Wireless Theories & Technol Lab Beijing Peoples R China

ISBN: (纸本)9781424402632

There have been great efforts to study the adaptive MIMO systems, while all of them concentrate on the systems without channel coding. This paper presents a new adaptive V-BLAST scheme adopting turbo-codes as the channel coding. This new scheme divides the optimization problem into two steps which simplifies the design greatly. Also, through this two-step method, we derive two algorithms for fixed rate and variable rate applications respectively. We combine the bit and power allocation with antenna selection effectively with very low complexity through a new ordering scheme and derive a simplified power allocation algorithm. For adaptive coding, we propose a new metric - Equivalent Capacity SNR, which can indicate the overall channel condition, to select the proper coding scheme. Simulation results show that the algorithms for fixed rate and variable rate both provide very good throughput performance with low complexity and less feedback information.

关键词： adaptive V-BLAST adaptive coding antenna selection bit and power allocation

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Capacity and Coverage Planning for Networks of Small Mobile Terminals in the C and Ku Bands

Capacity and Coverage Planning for Networks of Small Mobile ...

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MILCOM Military Communications Conference

作者： McLain, Chris Gonzalez, Lino LinQuest Corp Los Angeles CA 90056 USA

ISBN: (纸本)9781424481804

Networks of small mobile terminals are proliferating in bands that were previously only used for fixed terminals, such as C band and Ku band, for aeronautical, maritime, and land mobile applications in both the government and commercial domains. Some of these networks are assembled using multiple beams on multiple satellites to achieve global reach. The ability to set up new mobile networks without launching dedicated satellites and to draw capacity from a deep global market for transponders will undoubtedly encourage even more entrants into this field. Planning complex mobile network requires actions that are common with fixed networks: Calculating user data rate demand in each regions covered Selecting appropriate satellites and beams for those regions Determining the required bandwidth and power to lease in each beam Selecting optimal carrier configurations for those beams However, planning these networks poses challenges that are not typically faced in fixed satellite applications including: Regulatory off-axis EIRP and downlink power spectral density limits that are challenging for small mobile terminals Link performance that varies widely across the satellite coverage area as a result of satellite and mobile terminal performance Assembling multiple satellite beams into a contiguous network coverage area This paper will elucidate some of the common trades that mobile network planners face, discuss analytical techniques for optimizing mobile networks, and provide practical advice to planners of such networks. The focus of this paper will be mobile networks with a hub and spoke topology that use an adaptive coding and Modulation (ACM) waveform on the forward link (hub to terminal), such as DVB-S2, and a Time Division Multiple Access (TDMA) waveform on the return link (terminal to hub), such as iDirect or the JIPM modem. Examples of aeronautical and maritime network will be used. Similar concepts and techniques can be used to plan these networks using new WGS cons

关键词： C band DVB-S2 JIPM modem Ku band adaptive codes adaptive coding adaptive modulation aeronautical application capacity planning coverage planning digital video broadcasting fixed satellite applications hub topology iDirect land mobile application maritime

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LTE Relay Architecture and Its Upper Layer Solutions

LTE Relay Architecture and Its Upper Layer Solutions

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IEEE Global Telecommunications Conference (GLOBECOM 2010)

作者： Huang, Xiaolong Ulupinar, Fatih Agashe, Parag Ho, Duncan Bao, Gang

ISBN: (纸本)9781424456383

the relay technology is an essential piece of LTE-Advanced in its pursuit of cost effective capacity enhancement and coverage extension. Simple RF repeaters have been widely used in cellular technologies to offer coverage extension. However, they cannot distinguish desired signals from interference and noise and are unable to operate with sophisticated mechanisms, such as power control, beam-forming, and adaptive modulating/coding. As a result, simple RF repeaters do not provide capacity enhancement nor do they reach the capacity potential of extended coverage areas. The use of more sophisticated relay in cellular technologies is relatively new. With its great benefits in QoS differentiation, capacity enhancement, and coverage extension, the development of LTE relay technology faces challenges in providing backward compatibility, minimizing complexity, providing sufficient QoS differentiation, reducing over the air overhead, and ensuring security. This paper addresses these challenges with solutions in the aspect of relay architecture and upper layer designs.

关键词： LTE relay architecture LTE-advanced Long Term Evolution QoS differentiation adaptive codes adaptive coding adaptive modulation adaptive modulation array signal processing beamforming capacity enhancement cellular technology interference interference (sign

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