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 new formulation of the system equations that describe the behavior of the one-dimensional M-band maximally decimated analysis/synthesis filter bank system is presented. The development incorporates the effects of the shift-varying nature of the upsampling and downsampling operations. By explicitly including the filter regions of support, one is able to derive a more general expression for the relationships that must exist between the analysis and synthesis filters in order to cancel all interband aliasing. From this expression one can find (1) the M/sup M-1/ distinct sets of analysis and synthesis filters from which an M-band alias-free filter bank can be constructed, and (2) the constraints on how these filters, once designed, can be shifted without destroying their aliasing cancellation properties. >

Support constraints for M-band alias-free filter banks

We present the application of Bambeger pyramids to the removal of speckle noise from SAR images using subband domain shrinking. Bamberger pyramids provide better directional selectivity than the commonly used 2D UDWT allowing better representation of edges and geometrical structures. We show that Bamberger pyramids provide superior speckle removal and edge retention properties when compared to the 2D UDWT, and the commonly used Lee MMSE filter.

SAR Image Speckle Removal using Bamberger Pyramids

We propose a hybrid low bit-rate subband video coding scheme utilizing context models, rate-constrained motion estimation and overlapped motion compensation. Emerging efficient context-based entropy coding techniques fit very well into wavelet/subband-based coding systems, making them very attractive candidates for the entropy coding part of a wavelet/subband-based video coding scheme. A multidimensional probability modeling technique along with context-based entropy coding are utilized to exploit redundancies in the subband structure, yielding better compression.

Low bit-rate subband video coding using context models

In this paper the Cooley-Tukey fast Fourier transform (FFT) algorithm is generalized to the multi-dimensional case in a natural way that incorporates the standard row-column and vector-radix algorithms as special cases. It can be used for the evaluation of discrete Fourier transforms of rectangularly or hexagonally sampled signals or signals which are arbitrarily sampled in either the spatial or Fourier domain. These fast Fourier transform algorithms are shown to result from the factorization of an integer matrix; different algorithms correspond to different factorizations. This paper will first derive a generalized discrete Fourier transform, then derive the general Cooley-Tukey algorithm, and conclude by interpreting existing multi-dimensional FFT algorithms in terms of the generalized one.

Generalized cooley-tukey algorithms for evaluation of multi-dimensional discrete fourier transforms

A contour-based hybrid scheme for video sequence displacement estimation is described. It is a combination of a contour-based and a multiframe gradient-based algorithm. By using three successive image frames, the proposed system can select reliable motion-related-frame differences, extract moving edge tokens, and ignore noise. The contour-based estimation method can provide a reasonable initial displacement estimate for each moving edge neighborhood. As only one motion vector per edge neighborhood needs to be transmitted and the receiver can find the edge and region information by itself, this approach can reduce the overhead bits to be transmitted. To complete a low-bit-rate video coding system, some coding algorithms need to be applied to transmit the motion-compensated frame differences. >

Russell M. Mersereau

Papers

Support constraints for M-band alias-free filter banks

SAR Image Speckle Removal using Bamberger Pyramids

Low bit-rate subband video coding using context models

Generalized cooley-tukey algorithms for evaluation of multi-dimensional discrete fourier transforms

Contour-based hybrid displacement estimation for image sequence compression