Página 18 dos resultados de 700 itens digitais encontrados em 0.024 segundos

A Fast Algorithm and Testbed Evaluation for Sound Source Localization Using Sensor Networks

Johnston, Brian; Yin, Xiaoming; Valenzuela, Adrian; Frantz, Patrick; Johnston, Brian; Yin, Xiaoming; Valenzuela, Adrian; Frantz, Patrick
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
Conference Paper; The theoretical idea of a network composed of small, low-cost sensor nodes able to localize the source of acoustic events has the potential to make a multitude of exciting applications possible. However, this potential can only be realized if computationally tractable algorithms are employed. In this paper, we propose a novel algorithm that offers not only low computational complexity, but also high accuracy, making it an excellent choice for implementation on low-power systems. Moreover, we have developed a flexible sensor network testbed and utilized it to determine the performance of our algorithm relative to existing methods. Finally, we present the results of our experimentation using real data collected with our sensor nodes, demonstrating the effectiveness of our localization scheme, and showing that our hardware platform is well-suited to the needs of sensor network applications.

Wavelet-based Deconvolution for Ill-conditioned Systems

Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G.; Neelamani, Ramesh; Choi, Hyeokho; Baraniuk, Richard G.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
Conference Paper; In this paper, we propose a new approach to wavelet-based deconvolution. Roughly speaking, the algorithm comprises Fourier-domain system inversion followed by wavelet-domain noise suppression. Our approach subsumes a number of other wavelet-based deconvolution methods. In contrast to other wavelet-based approaches, however, we employ a regularized inverse filter, which allows the algorithm to operate even when the inverse system is ill-conditioned or non-invertible. Using a mean-square-error metric, we strike an optimal balance between Fourier-domain and wavelet-domain regularization. The result is a fast deconvolution algorithm ideally suited to signals and images with edges and other singularities. In simulations with real data, the algorithm outperforms the LTI Wiener filter and other wavelet-based deconvolution algorithms in terms of both visual quality and MSE performance.

Multiscale Image Segmentation Using Joint Texture and Shape Analysis

Neelamani, Ramesh; Romberg, Justin; Riedi, Rudolf H.; Choi, Hyeokho; Baraniuk, Richard G.; Neelamani, Ramesh; Romberg, Justin; Riedi, Rudolf H.; Choi, Hyeokho; Baraniuk, Richard G.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
Conference Paper; We develop a general framework to simultaneously exploit texture and shape characterization in multiscale image segmentation. By posing multiscale segmentation as a model selection problem, we invoke the powerful framework offered by minimum description length (MDL). This framework dictates that multiscale segmentation comprises multiscale texture characterization and multiscale shape coding. Analysis of current multiscale maximum a posteriori (MAP) segmentation algorithms reveals that these algorithms implicitly use a shape coder with the aim to estimate the optimal MDL solution, but find only an approximate solution. Towards achieving better segmentation estimates, we first propose a shape coding algorithm based on zero-trees which is well-suited to represent images with large homogeneous regions. For this coder, we design an efficient tree-based algorithm using dynamic programming that attains the optimal MDL segmentation estimate. To incorporate arbitrary shape coding techniques into segmentation, we design an iterative algorithm that uses dynamic programming for each iteration. Though the iterative algorithm is not guaranteed to attain exactly optimal estimates, it more effectively captures the prior set by the shape coder. Experiments demonstrate that the proposed algorithms yield excellent segmentation results on both synthetic and real world data examples.

Optimal Signaling Strategies for Symmetric and Asymmetric Bit-Rate Communication Services in the Presence of Crosstalk

Gaikwad, Rohit; Baraniuk, Richard G.; Gaikwad, Rohit; Baraniuk, Richard G.
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Relatório
Português
Relevância na Pesquisa
25.48%
Tech Report; We have invented a new modem technology for transmitting data on conventional telephone lines (twisted pairs) at high speeds. This discovery is timely, as new standards are being developed for this Digital Subscriber Line (DSL) technology at this very moment. The potential market for the new modem technology is massive, as the telephone service providers wish to offer Internet access to the masses using the current phone lines into the home. Key to the deployment of any new service is the distribution of power over frequency, for new services must be designed to be robust to interference that might be caused by other services that are carried by neighboring telephone lines. As well, new services cannot interfere with existing services. We have made two discoveries. The first is an optimization technique that provides the best possible distribution of power (over frequency) for any new DSL service given the interference from other known services that are carried by neighboring telephone lines in the same cable. The second is a power istribution scheme that minimizes the interference caused by the new DSL service into neighboring lines. This new modem technology can be applied to many channels besides the telephone channel (for example...

A Hierarchical Wavelet-Based Framework for Pattern Analysis and Synthesis

Scott, Clayton; Scott, Clayton
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.48%
Masters Thesis; Despite their success in other areas of statsitical signal processing, current wavelet-based image models are inadequate for modeling patterns in images, due to the presence of unknown transformations inherent in most pattern observations. In this thesis we introduce a hierarchical wavelet-based framework for modeling patterns in digital images. This framework takes advantage of the efficient image representations afforded by wavelets, while accounting for unknown pattern transformations. Given a trained model, we can use this framework to synthesize pattern observations. If the model parameters are unknown, we can infer them from labeled training data using TEMPLAR, a novel template learning algorithm with linear complexity. TEMPLAR employs minimum description length (MDL) complexity regularization to learn a template with a sparse representation in the wavelet domain. If we are given several trained models for different patterns, our framework provides a low-dimensional subspace classifier that is invariant to unknown pattern transformations as well as background clutter.

Small-time scaling behaviors of Internet backbone traffic: An empirical study

Zhang, Zhi-Li; Ribeiro, Vinay Joseph; Moon, Sue; Diot, Christophe; Zhang, Zhi-Li; Ribeiro, Vinay Joseph; Moon, Sue; Diot, Christophe
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
Conference Paper; We study the small-time (sub-seconds) scaling behaviors of Internet backbone traffic, based on traces collected from OC3/12/48 links in a tier-1 ISP. We observe that for a majority of these traces, the (second-order) scaling exponents at small time scales (1ms - 100ms) are fairly close to 0.5, indicating that traffic fluctuations at these time scales are (nearly) uncorrelated. In addition, the traces manifest mostly monofractal behaviors at small time scales. The objective of the paper is to understand the potential causes or factors that influence the small-time scalings of Internet backbone traffic via empirical data analysis. We analyze the traffic composition of the traces along two dimensions â flow size and flow density. Our study uncovers dense flows (i.e., flows with bursts of densely clustered packets) as the correlation-causing factor in small time scales, and reveals that the traffic composition in terms of proportions of dense vs. sparse flows plays a major role in influecing the small-time scalings of aggregate traffic.

Structured Parallel Architecture for Displacement MIMO Kalman Equalizer in CDMA Systems

Guo, Yuanbin; Zhang, Jianzhong; McCain, Dennis; Cavallaro, Joseph R.
Fonte: IEEE Publicador: IEEE
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
25.48%
A reduced complexity MIMO Kalman equalizer architecture is proposed in this brief by jointly considering the displacement structure and the block-Toeplitz structure. Numerical matrix–matrix multiplications with O(F3) complexity are eliminated by simple data loading process, where is the spreading factor. Finally, an iterative Conjugate-Gradient based algorithm is proposed to avoid the inverse of the Hermitian symmetric innovation covariance matrix in Kalman gain processor. The proposed architecture not only reduces the numerical complexity from O(F2) to O(Flog2F) per chip, but also facilitates the parallel and pipelined VLSI implementation in real-time processing.

A Massively Parallel Implementation of QC-LDPC Decoder on GPU

Wang, Guohui; Wu, Michael; Sun, Yang; Cavallaro, Joseph R.
Fonte: IEEE Publicador: IEEE
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
The graphics processor unit (GPU) is able to provide a low-cost and flexible software-based multi-core architecture for high performance computing. However, it is still very challenging to efficiently map the real-world applications to GPU and fully utilize the computational power of GPU. As a case study, we present a GPU-based implementation of a real-world digital signal processing (DSP) application: low-density parity-check (LDPC) decoder. The paper shows the efforts we made to map the algorithm onto the massively parallel architecture of GPU and fully utilize GPU’s computational resources to significantly boost the performance. Moreover, several efficient data structures have been proposed to reduce the memory access latency and the memory bandwidth requirement. Experimental results show that the proposed GPU-based LDPC decoding accelerator can take advantage of the multi-core computational power provided by GPU and achieve high throughput up to 100.3Mbps.

Distributed Decoding in Cooperative Communications

Karkooti, Marjan; Cavallaro, Joseph R.
Fonte: IEEE Publicador: IEEE
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
In this paper, we present a novel relaying strategy called distributed and partial decoding. This strategy can be viewed as a variation of the decode and forward with the difference that the relay partially decodes the signal, re-transmits it to the destination, and the destination continues the decoding. By distributing the decoding process between the relay and the destination, the relay uses less processing power and less time. This is very suitable for practical applications in which relays are battery-operated (such as handsets) and do not want to use all their battery power on relaying the data of other users.

Reconfigurable Architectures for Wireless Systems: Design Exploration and Integration Challenges

Cavallaro, Joseph R.; Brogioli, Michael C.; de Baynast, Alexandre; Radosavljevic, Predrag
Fonte: WWRF Publicador: WWRF
Tipo: Conference paper
Português
Relevância na Pesquisa
25.48%
Mobile devices are severely power and area limited due to battery capacity and system size. In many of these example systems, advanced features require computationally complex signal processing on high-speed data streams for enhanced networking capabilities. Thus, mapping high-level communication and networking algorithms to system architectures is a complex and challenging procedure. An important challenge is to characterize the area, time, and power requirements of these embedded system modules and to use this information effectively to determine the architecture of programmable, reconfigurable, and fixed-function modules. In this paper, we will focus on application examples in wireless networking which highlight these challenges in reconfigurable systems integration.

A Bit More To IT: Scholarly Communication Forums as Socio-Technical Interaction Networks

Kling, Rob; McKim, Geoffrey; King, Adam
Fonte: Rob Kling Center for Social Informatics Publicador: Rob Kling Center for Social Informatics
Tipo: Trabalho em Andamento Formato: 70329 bytes; 96707 bytes; 87393 bytes; 109164 bytes; 10176 bytes; 119138 bytes; image/jpeg; image/jpeg; image/jpeg; image/jpeg; image/jpeg; text/html
Português
Relevância na Pesquisa
25.48%
In this article, we examine the conceptual models that help us understand the development and sustainability of scholarly and professional communication forums on the Internet, such as conferences, pre-print servers, field-wide data sets, and collaboratories. We first present and document the information processing model that is implicitly advanced in most discussions about scholarly communications -- the “Standard Model.” Then we present an alternative model, a model that considers information technologies as Socio-Technical Interaction Networks (STINs). STIN models provide a richer understanding of human behavior with online scholarly communications forums. They also help to further a more complete understanding of the conditions and activities that support the sustainability of these forums within a field than does the Standard Model. We illustrate the significance of the STIN model with examples of scholarly communication forums drawn from the fields of high energy physics, molecular biology, and information systems.; Indiana University

An automatic data processing charge back system for the fleet numerical oceanography center.

Leonard, Robert P.
Fonte: Monterey, California. Naval Postgraduate School Publicador: Monterey, California. Naval Postgraduate School
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.48%

Analysis of management control techniques for the data processing department at the Navy Finance Center, Cleveland, Ohio.

McGloon, James William.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
25.48%

A dual-spectrometer approach to reflectance measurements under sub-optimal sky conditions

Bachmann, Charles M.; Montes, Marcos J.; Parrish, Christopher E.; Fusina, Robert A.; Nichols, C. Reid; Li, Rong-Rong; Hallenborg, Eric; Jones, Christopher A.; Lee, Krista; Sellars, Jon; White, Stephen A.; Fry, John C.
Fonte: Escola de Pós-Graduação Naval Publicador: Escola de Pós-Graduação Naval
Português
Relevância na Pesquisa
25.48%
Optics Express, Volume 20, No. 8, pp. 8959-8973 (2012); This paper presents a practical method for the development of spectral reflectance libraries under sub-optimal sky conditions. Although there are commercially available spectrometers which simultaneously measure both downwelling and upwelling radiance to mitigate the impact of sub-optimal sky conditions, these spectrometers only record in the visible and near infra-red. There are presently no commercially available spectrometers with this capability that can record the visible through shortwave infra-red. This paper presents a practical method of recording and processing data using coordinated measurements from two full-range spectrometers and discusses potential pitfalls and solutions required to achieve accurate reflectance spectra. Results demonstrate that high-quality spectral reflectance libraries can be developed with this approach.

Lightly supervised acquisition of named entities and linguistic patterns for multilingual text mining

Pablo-Sánchez, César de; Segura Bedmar, Isabel; Martínez, Paloma; Iglesias, Ana
Fonte: Springer Publicador: Springer
Tipo: info:eu-repo/semantics/acceptedVersion; info:eu-repo/semantics/article Formato: text/plain; application/pdf
Publicado em 01/05/2012 Português
Relevância na Pesquisa
25.48%
Named Entity Recognition and Classification (NERC) is an important component of applications like Opinion Tracking, Information Extraction, or Question Answering. When these applications require to work in several languages, NERC becomes a bottleneck because its development requires language-specific tools and resources like lists of names or annotated corpora. This paper presents a lightly supervised system that acquires lists of names and linguistic patterns from large raw text collections in western languages and starting with only a few seeds per class selected by a human expert. Experiments have been carried out with English and Spanish news collections and with the Spanish Wikipedia. Evaluation of NE classification on standard datasets shows that NE lists achieve high precision and reveals that contextual patterns increase recall significantly. Therefore, it would be helpful for applications where annotated NERC data are not available such as those that have to deal with several western languages or information from different domains.; This researchwork has been supported by the Regional Government of Madrid under the Research Network MA2VICMR (S2009/TIC-1542), by the Spanish Ministry of Education under the project MULTIMEDICA (TIN2010-20644-C03-01) and by the Spanish Center for Industry Technological Development (CDTI...

Natural Resources in Latin America and the Caribbean : Beyond Booms and Busts?; Los recursos naturales en America Latina y el Caribe : mas alla de bonanzas y crisis?

Sinnott, Emily; Nash, John; de la Torre, Augusto
Fonte: World Bank Publicador: World Bank
Tipo: Publications & Research :: Publication; Publications & Research :: Publication
Português
Relevância na Pesquisa
25.48%
Throughout, the history of the Latin America and Caribbean (LAC) region, natural resource wealth has been critical for its economies. Production of precious metals, sugar, rubber, grains, coffee, copper, and oil have at various periods of history made countries in Latin America-and their colonial powers-some of the most prosperous in the world. In some ways, these commodities may have changed the course of history in the world at large. Latin America produced around 80 percent of the world's silver in the 16th through 19th centuries, fueling the monetary systems of not only Europe, but China and India as well. The dramatic movements in commodity markets since the early 2000s, as well as the recent economic crisis, provide new data to analyze and also underscore the importance of a better understanding of issues related to boom-bust commodity cycles. The current pattern of global recovery has favored LAC so far. Countercyclical policies have supported domestic demand in the larger LAC economies, and external demand from fast-growing emerging markets has boosted exports and terms of trade for LAC's net commodity exporters. Prospects for LAC in the short term look good. Beyond the cyclical rebound...

Gender-Inclusive Nutrition Activities in South Asia : Mapping Report

Sen, Soham; Hook, Mikael
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Economic & Sector Work :: Social Analysis; Economic & Sector Work
Português
Relevância na Pesquisa
25.48%
This report is the first of a series that will explore how gender can be more comprehensively incorporated into nutrition interventions in the South Asia Region in order to improve the effectiveness these programs. The first section presents the rationale for considering gender in nutrition programs in the first place, moving beyond traditional services for mothers and children. It draws from the literature to describe why gender is an important factor for the high under-nutrition rates in South Asia and how a broad range of gender issues, rooted in a mother's capacity to care for herself and her child, affect nutritional outcomes of children. The second section presents the results of a mapping of nutrition programs in the South Asia Region. The mapping primarily finds that, despite its importance, gender is too narrowly addressed in most interventions. Existing programs typically focus on the first two approaches mentioned above: imparting nutritional knowledge and skills to the caregiver and improving physical health through food or micronutrient supplements and health services. The third section identifies several nutrition and health projects that have adopted promising approaches to include gender more comprehensively. To improve household support for the mother in providing child care...

Gazing Into the Mirror II : Performance Contracts in Cameroon Customs; Se regarder dans le miroir : Deuxieme volume - Les contrats de performance dans les douanes Camerounaises

Likeng, Minette Libom Li; Djeuwo, Marcellin; Bilangna, Samson
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Working Paper; Publications & Research
Português
Relevância na Pesquisa
25.48%
This paper revolves around the World Customs Organization's (WCO) 2011 theme of the year, 'knowledge as a catalyst for excellence'. The contracts clearly define the scope and procedures for their implementation. In light of the foregoing, the policy for performance contracts is part of the effort to implement the plan to reform the Customs Administration. These contracts aim to combat customs fraud and corruption more effectively, and introduce speed and efficiency in the processing of files. In other words, the contracts, which are based on objective indicators, seek performance, responsibility, and transparency, with a particular emphasis on ethics. Inspectors who sign the contract must work swiftly, while seeking to uncover fraud. To that end, they must be present at their work stations, behave in a professional manner, and themselves be confident that their contribution to efforts to reduce clearance times and costs of goods is essential. In sum, the procedure seeks to enhance the performance of Cameroon customs with a view to providing quality service to enterprises...

Mozambique : Student Assessment

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Working Paper; Publications & Research
Português
Relevância na Pesquisa
25.48%
In 2009, Mozambique joined the Russia Education Aid for Development (READ) trust fund program, the goal of which is to help countries improve their capacity to design, carry out, analyze, and use assessments for improved student learning. As part of the READ trust fund program, and in order to gain a better understanding of the strengths and weaknesses of its existing assessment system, Mozambique participated in a formal exercise to benchmark this system under The World Bank's Systems Approach for Better Education Results (SABER) program. SABER is an evidence-based program to help countries systematically examine and strengthen the performance of different aspects of their education systems. SABER-student assessment is a component of the SABER program that focuses specifically on benchmarking student assessment policies and systems. The goal of SABER-student assessment is to promote stronger assessment systems that contribute to improved education quality and learning for all. The importance of assessment is linked to its role in: providing information on levels of student learning and achievement in the system; monitoring trends in education quality over time; supporting educators and students with real-time information to improve teaching and learning; and holding stakeholders accountable for results. The SABER-student assessment framework is built on the available evidence base for what an effective assessment system looks like. The framework provides guidance on how countries can build more effective student assessment systems. The framework is structured around two main dimensions of assessment systems: the types/purposes of assessment activities and the quality of those activities. Assessment systems tend to be comprised of three main types of assessment activities...

Armenia : Student Assessment

World Bank
Fonte: Washington, DC Publicador: Washington, DC
Tipo: Publications & Research :: Working Paper; Publications & Research
Português
Relevância na Pesquisa
25.48%
In 2011, Armenia joined the Russia Education Aid for Development (READ) trust fund program, the goal of which is to help countries improve their capacity to design, carry out, analyze, and use assessments for improved student learning. As part of the READ Trust Fund program, and in order to gain a better understanding of the strengths and weaknesses of its existing assessment system, Armenia participated in a formal exercise to benchmark its student assessment system under The World Bank's Systems Approach for Better Education Results (SABER) program. SABER is an evidence-based program to help countries systematically examine and strengthen the performance of different aspects of their education systems. SABER-student assessment is a component of the SABER program that focuses specifically on benchmarking student assessment policies and systems. The goal of SABER-student assessment is to promote stronger assessment systems that contribute to improved education quality and learning for all. The importance of assessment is linked to its role in: providing information on levels of student learning and achievement in the system; monitoring trends in education quality over time; supporting educators and students with real-time information to improve teaching and learning; and holding stakeholders accountable for results. The SABER-student assessment framework is built on the available evidence base for what an effective assessment system looks like. The framework provides guidance on how countries can build more effective student assessment systems. The framework is structured around two main dimensions of assessment systems: the types/purposes of assessment activities and the quality of those activities. Assessment systems tend to be comprised of three main types of assessment activities...