Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have significant impact on the overall energy dissipation of these networks. Based on our findings that the conventional protocols of direct transmission, minimum-transmission-energy, multi-hop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster based station (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show the LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional outing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

/pdf/energy-efficient-communication-protocol-for-wireless-4vhuagusz2.pdf

Energy-efficient communication protocol for wireless microsensor networks

Wireless distributed microsensor systems will enable the reliable monitoring of a variety of environments for both civil and military applications. In this paper, we look at communication protocols, which can have signicant impact on the overall energy dissipation of these networks. Based on our ndings that the conventional protocols of direct transmission, minimum-transmission-energy, multihop routing, and static clustering may not be optimal for sensor networks, we propose LEACH (Low-Energy Adaptive Clustering Hierarchy), a clustering-based protocol that utilizes randomized rotation of local cluster base stations (cluster-heads) to evenly distribute the energy load among the sensors in the network. LEACH uses localized coordination to enable scalability and robustness for dynamic networks, and incorporates data fusion into the routing protocol to reduce the amount of information that must be transmitted to the base station. Simulations show that LEACH can achieve as much as a factor of 8 reduction in energy dissipation compared with conventional routing protocols. In addition, LEACH is able to distribute energy dissipation evenly throughout the sensors, doubling the useful system lifetime for the networks we simulated.

Energy-efficient communication protocols for wireless microsensor networks

Determining optical flow

Deposits of clastic carbonate-dominated (calciclastic) sedimentary slope systems in the rock record have been identified mostly as linearly-consistent carbonate apron deposits, even though most ancient clastic carbonate slope deposits fit the submarine fan systems better. Calciclastic submarine fans are consequently rarely described and are poorly understood. Subsequently, very little is known especially in mud-dominated calciclastic submarine fan systems. Presented in this study are a sedimentological core and petrographic characterisation of samples from eleven boreholes from the Lower Carboniferous of Bowland Basin (Northwest England) that reveals a >250 m thick calciturbidite complex deposited in a calciclastic submarine fan setting. Seven facies are recognised from core and thin section characterisation and are grouped into three carbonate turbidite sequences. They include: 1) Calciturbidites, comprising mostly of highto low-density, wavy-laminated bioclast-rich facies; 2) low-density densite mudstones which are characterised by planar laminated and unlaminated muddominated facies; and 3) Calcidebrites which are muddy or hyper-concentrated debrisflow deposits occurring as poorly-sorted, chaotic, mud-supported floatstones. These

Phd by thesis

An automated method for segmenting magnetic resonance head images into brain and non-brain has been developed. It is very robust and accurate and has been tested on thousands of data sets from a wide variety of scanners and taken with a wide variety of MR sequences. The method, Brain Extraction Tool (BET), uses a deformable model that evolves to fit the brain's surface by the application of a set of locally adaptive model forces. The method is very fast and requires no preregistration or other pre-processing before being applied. We describe the new method and give examples of results and the results of extensive quantitative testing against "gold-standard" hand segmentations, and two other popular automated methods.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/hbm.10062

Fast robust automated brain extraction

A common framework is presented for treating the nominally dissimilar problems of signal deconvolution and the reconstruction of multidimensional signals from projections. Iterative solutions to both problems are given which permit constraints to be imposed on the class of feasible solutions. Variations on these solutions which permit the utilization of statistical knowledge about the signal and its distortion are given and these are related to problems in recursive least squares estimation.

Iterative Algorithms for Deconvolution and Reconstruction of Multidimensional Signals from Their Projections

There are several applications in image communication where digital data is incorporated into the image. These applications include digital watermarking for intellectual property protection and authentication, captioning, and steganography in which two or more parties can communicate through an invisible or “subliminal” covert communication channel. These applications range in the amount of data embedded, security, hostility of the attack and protection against deliberate or incidental attacks. This research examines the issue of information hiding in still images and its application to digital multimedia applications. It develops a general model for still images as a constrained type covert communication channel. Novel schemes for data embedding are developed for different data hiding applications such digital watermarking and steganography. Tradeoffs between data emedding capacity, security, and robustness to attacks are examined. Information theoretic approaches are developed to give bounds for estimating the capacity to hide information for these schemes. Analysis and design for these schemes for data hiding application is discussed.

Theory and applications of data hiding in still images

The problem of automatically designing efficient implementations of digital signal processing (DSP) algorithms based on application-specific information is considered. A rule-based code simplification system is presented that is capable of performing code simplifications on a broad class of programs. Several types of symbolic processing rules and their uses in the problem of code pruning are discussed. The design of efficient radix-2 FFT programs is presented as an example, and it is shown that considerable operational savings can be obtained if certain properties of the input data are known. >

http://ieeexplore.ieee.org/iel2/815/3148/00100346.pdf

Symbolic simplification of digital signal processing software

Two representative sample images of Band 4 of the Landsat Thematic Mapper are compressed with the JPEG algorithm at 8:1, 16:1 and 24:1 Compression Ratios for experimental browsing purposes. We then apply the Optimal PSNR Estimated Spectra Adaptive Postfiltering (ESAP) algorithm to reduce the DCT blocking distortion. ESAP reduces the blocking distortion while preserving most of the image's edge information by adaptively postfiltering the decoded image using the block's spectral information already obtainable from each block's DCT coefficients. The algorithm iteratively applied a one dimensional log-sigmoid weighting function to the separable interpolated local block estimated spectra of the decoded image until it converges to the optimal PSNR with respect to the original using a 2-D steepest ascent search. Convergence is obtained in a few iterations for integer parameters. The optimal logsig parameters are transmitted to the decoder as a negligible byte of overhead data. A unique maxima is guaranteed due to the 2-D asymptotic exponential overshoot shape of the surface generated by the algorithm. ESAP is based on a DFT analysis of the DCT basis functions. It is implemented with pixel-by-pixel spatially adaptive separable FIR postfilters. PSNR objective improvements between 0.4 to 0.8 dB are shown together with their corresponding optimal PSNR adaptive postfiltered images.

Blocking reduction of Landsat Thematic Mapper JPEG browse images using optimal PSNR estimated spectra adaptive postfiltering

A major drawback of block-based still image or video compression methods at low rates are the visible block boundaries that are also known as blocking artifacts. Several methods have been proposed in the literature to reduce these artifacts for video sequences. However, most are simply adaptations of still image blocking artifact reduction methods, which do not exploit temporal information. We propose a novel multi-frame blocking artifact reduction method that incorporates temporal information effectively. This method uses the spatial correlations that exist between the successive frames to define constraint sets at multiple frames and provides a Projections Onto Convex Sets (POCS) solution. The proposed method operates solely on transform domain (DCT) data, and hence provides a solution that is compatible with the observed video. It does not need to make any spatial smoothness assumptions, which are typical with blocking artifact reduction algorithms for still images.

Russell M. Mersereau

Papers

Iterative Algorithms for Deconvolution and Reconstruction of Multidimensional Signals from Their Projections

Theory and applications of data hiding in still images

Symbolic simplification of digital signal processing software

Blocking reduction of Landsat Thematic Mapper JPEG browse images using optimal PSNR estimated spectra adaptive postfiltering

A multi-frame blocking artifact reduction method for transform-coded video