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A non-parametric vessel detection method for complex vascular structures

QIAN, Xiaoning; BRENNAN, Matthew P.; DIONE, Donald P.; DOBRUCKI, Wawrzyniec L.; JACKOWSKI, Marcel P.; BREUER, Christopher K.; SINUSAS, Albert J.; PAPADEMETRIS, Xenophon
Fonte: ELSEVIER SCIENCE BV Publicador: ELSEVIER SCIENCE BV
Tipo: Artigo de Revista Científica
ENG
Relevância na Pesquisa
26.05%
Modern medical imaging techniques enable the acquisition of in vivo high resolution images of the vascular system. Most common methods for the detection of vessels in these images, such as multiscale Hessian-based operators and matched filters, rely on the assumption that at each voxel there is a single cylinder. Such an assumption is clearly violated at the multitude of branching points that are easily observed in all, but the Most focused vascular image studies. In this paper, we propose a novel method for detecting vessels in medical images that relaxes this single cylinder assumption. We directly exploit local neighborhood intensities and extract characteristics of the local intensity profile (in a spherical polar coordinate system) which we term as the polar neighborhood intensity profile. We present a new method to capture the common properties shared by polar neighborhood intensity profiles for all the types of vascular points belonging to the vascular system. The new method enables us to detect vessels even near complex extreme points, including branching points. Our method demonstrates improved performance over standard methods on both 2D synthetic images and 3D animal and clinical vascular images, particularly close to vessel branching regions. (C) 2008 Elsevier B.V. All rights reserved.; NIH[R01HL065662]; NIH; NIH[R01EB006494]; NIH; American Surgical Association Research Fellowship Award; American Surgical Association Research Fellowship Award

Integration of local pattern elements into a global shape in human vision

Saarinen, Jukka; Levi, Dennis M.; Shen, Bridgitte
Fonte: The National Academy of Sciences of the USA Publicador: The National Academy of Sciences of the USA
Tipo: Artigo de Revista Científica
Publicado em 22/07/1997 EN
Relevância na Pesquisa
16.2%
The spatial extent of the cortical filters selective for different spatial frequencies and orientations is limited. We studied psychophysically how information from the local filters is integrated into global pattern shapes, i.e., whether performance in the identification of a global pattern consisting of small, locally oriented Gabor elements depends on the orientations of those elements. The observer was presented with an E-like stimulus pattern shape comprised of oriented Gabor patches on a blank background, and the performance measure was the threshold contrast for identifying the orientation of the E pattern (four possible rotated orientations). The results showed that contrast thresholds were significantly lower when the local elements all shared the same orientation (e.g., all horizontal) compared with the condition in which the elements had mixed orientations (both horizontal and vertical). The enhancement effect due to uniform local orientations can be explained by two factors: One is local facilitatory interactions between the orientation selective filters, and the other is second-order information integration across the filters.

Beta 2 (CD18) and beta 1 (CD29) integrin mechanisms in migration of human polymorphonuclear leucocytes and monocytes through lung fibroblast barriers: shared and distinct mechanisms.

Shang, X Z; Issekutz, A C
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /12/1997 EN
Relevância na Pesquisa
25.87%
Accumulation of leucocytes in inflamed lung tissue and alveolar space involves their migration through vascular endothelium and then lung connective tissue. As a model of this process, we investigated human polymorphonuclear leucocyte (PMNL) and monocyte migration through a biological barrier of human lung fibroblasts (HLF) grown on polycarbonate filters. Very few PMNL (1-2%) or monocytes (3-8%) migrated through the HLF barriers spontaneously. Migration increased to 48-53% of added PMNL and 17-24% of added monocytes, when a C5a chemotactic gradient was present. The monocyte migration induced by C5a was not inhibited by monoclonal antibodies (mAb) to CD18 (beta 2 integrins). This CD18-independent migration was partially inhibited (35%) by mAb to gamma 5 of VLA-5 and completely inhibited by the combination of mAb to gamma 4 of VLA-4 with mAb to VLA-5, in the presence of mAb to CD18. In contrast, PMNL migration across HLF induced by C5a was partially inhibited by mAb to CD18 alone, but even with the addition of mAb to VLA-4, VLA-5 beta 1 and VLA-6, the greatest degree of inhibition was only 60%. Blocking the function of CD18 was not required to observe the inhibition by mAb to VLA-4, although the inhibitory effect of mAb to VLA-5 and VLA-6 alone or in combination was only observed when CD18 mechanisms were also blocked with anti-CD18 mAb. These results demonstrate that (a) both monocytes and PMNL can use either CD11/CD18 (beta 2 integrin) or beta 1 (CD49/CD29) integrins to migrate through HLF barriers; (b) in the case of monocytes...

INJECTING EQUPMENT SHARING AND PERCEPTION OF HIV AND HEPATITIS RISK AMONG INJECTING DRUG USERS IN BUDAPEST

Rácz, József; Gyarmathy, V. Anna; Neaigus, Alan; Ujhelyi, Eszter
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /01/2007 EN
Relevância na Pesquisa
16.3%
In Central European states, rates of HIV among IDUs have been low although HCV infection is widespread. The goal of our study was to assess HIV infection, risk perceptions and injecting equipment sharing among injection drug users in Budapest, Hungary. Altogether 150 IDUs were interviewed (121 structured between 1999-2000 and 29 ethnographic between 2003-2004). The majority of them injected heroin (52% and 79%) and many injected amphetamines (51% and 35%). One person tested positive for HIV. Two thirds (68% of 121) shared injecting equipment (syringes, cookers and filters). Some participants said they shared syringes because they were not carrying them for fear of police harassment, and that they reused filters as a backup drug supply. In multivariate analysis, sharing of injecting equipment was associated with higher perceived susceptibility to HIV/AIDS, lower self-efficacy for sterile equipment use, higher motivation to comply with peer pressure to use dirty injecting equipment, and with having a criminal record. The high levels of injecting risk behaviors found in this study are a cause for serious concern. HIV prevention interventions need to address not only sharing syringes but also sharing and reusing other injecting equipment and drug filters.

Transactional Memory Retry Mechanisms

Scott, Michael L. (1959 - ); Sveikauskas, Andrew ; Spear, Michael F. (1977 - )
Fonte: University of Rochester. Computer Science Department. Publicador: University of Rochester. Computer Science Department.
Tipo: Relatório
ENG
Relevância na Pesquisa
26.05%
Software Transactional Memory (STM) systems, if they support condition synchronization, typically do so through a retry mechanism. Using retry, a transaction explicitly self aborts and deschedules itself when it discovers that a precondition for its operation does not hold. The underlying implementation may then track the set of locations read by the retrying transaction, and refrain from scheduling the transaction for re-execution until at least one location in the set has been modified by another transaction. While retry is elegant and simple, the conventional implementation has several potential drawbacks that may limit both its efficiency and its generality. In this note, we present a retry mechanism based on Bloom filters that is entirely orthogonal to TM implementation. Our retry is compatible with hardware, software, and hybrid TM implementations, and has no impact on memory management or on the cache behavior of shared locations. It does, however, serialize writer transactions after their commit point when there are retrying transactions. We describe our mechanism and compare it to an optimized version of the conventional implementation.

Fast software transactions

Spear, Michael F. (1977 - ); Scott, Michael L. (1959 - )
Fonte: University of Rochester Publicador: University of Rochester
Tipo: Tese de Doutorado Formato: Number of Pages:xxi, 266 leaves
ENG
Relevância na Pesquisa
26.15%
Thesis (Ph. D.)--University of Rochester. Dept. of Computer Science, 2009.; In the past, only a small group of highly-skilled programmers were expected to write programs that used multiple processors simultaneously. However, microprocessor vendors have recently turned to multi-core chip designs as the most profitable way to increase performance. We are now seeing multi-core processors in desktops, laptops, handheld computers, and even embedded devices. As a result, parallel programming is becoming a core competency for all programmers. When concurrent threads of a parallel program share data, they must ensure that certain sets of accesses to shared memory execute as indivisible operations (that is, the regions must appear to execute atomically). The dominant mechanism for providing atomicity is mutual exclusion locks. Unfortunately, locks are a very low-level mechanism, widely regarded as too difficult for the average programmer to use correctly. Fortunately, locks are not the only mechanism that provides atomicity. Database transactions (used by millions of programmers to write highly concurrent e-commerce code) also ensure that regions of code execute atomically. Many efforts are underway to employ transactions to implement atomicity within general-purpose programming languages...

Cyberspace Law: Censorship and Regulation of the Internet

Travis, Hannibal B
Fonte: SelectedWorks Publicador: SelectedWorks
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
16.2%
Internet companies often define their missions as making the world’s knowledge available to everyone with access to the World Wide Web, and organizing content for easier accessibility. Internet filters threaten to censor expressive commentaries, slow the growth of innovative companies, and to change the nature of Google, Facebook, Twitter, and other popular Internet services. While limiting indecent, offensive, or illegal content, filters will sweep more broadly. Hannibal Travis, working with a variety of leading theorists of Internet regulation and a practitioner of cyberspace law from Silicon Valley, has released a book analyzing leading Internet law cases, entitled Cyberspace Law: Censorship and Regulation of the Internet. The book is being published by Routledge, a global publisher of academic books and journals. Chapters by Professor Travis provide an overview of key points in the regulation of cyberspace, including the ongoing struggle between the Federal Communications Commission and Internet infrastructure owners over net neutrality, the failed effort by the federal government to force “indecent” content behind credit-card filters that verified users’ ages, and initiatives by the Federal Trade Commission and private parties to improve privacy on Facebook. Contributions by Margreth Barrett of the University of California...

Aplicación de algoritmos combinados de filtrado adaptativo a acústica de salas

Azpicueta Ruiz, Luis Antonio
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado Formato: application/pdf
SPA
Relevância na Pesquisa
16.24%
Las aplicaciones de procesamiento de señales acústicas están cobrando una importancia creciente. La mayoría de aplicaciones de este tipo (como la cancelación de eco acústico, la cancelación de ruido, la dereverberación, la separación y el seguimiento de fuentes acústicas, etc.) requieren la identificación de una (o varias) respuestas al impulso del recinto (RIRs). Estas respuestas pueden variar con el tiempo, por lo que se precisa de esquemas adaptativos para su identificación. La utilización de esquemas adaptativos en escenarios de identificación de respuestas acústicas se ve sujeta a diferentes compromisos, como, p. ej., la conocida relación entre velocidad de convergencia y precisión en estacionario. Varios de estos compromisos se comparten con otras aplicaciones, mientras que otros son específicos del procesamiento de señales acústicas. Entre los diferentes métodos que tratan de aliviar estas limitaciones, destaca la combinación adaptativa de filtros adaptativos debido fundamentalmente a su sencillez, versatilidad y eficacia. En esta Tesis Doctoral se aborda el estudio, diseño, implementación y adecuación de los esquemas de combinación adaptativa para que resulten provechosos y convenientes en aplicaciones de procesamiento de señales acústicas. Para ello...

Advanced techniques for multicast service provision in core transport networks

Fernández del Carpio, Gonzalo
Fonte: Universidade Carlos III de Madrid Publicador: Universidade Carlos III de Madrid
Tipo: Tese de Doutorado Formato: application/pdf
ENG
Relevância na Pesquisa
16.3%
Although the network-based multicast service is the optimal way to support of a large variety of popular applications such as high-definition television (HDTV), videoon- demand (VoD), virtual private LAN service (VPLS), grid computing, optical storage area networks (O-SAN), video conferencing, e-learning, massive multiplayer online role-playing games (MMORPG), networked virtual reality, etc., there are a number of technological and operational reasons that prevents a wider deployment. This PhD work addresses this problem in the context of core transport network, by proposing and analyzing new cost-effective and scalable techniques to support multicast both at the Optical layer and at the Network layer (MPLS-IP networks). In the Optical layer, in particular in Wavelength Division Multiplexing (WDM) Optical Circuit Switched networks, current multicast-capable OXC node designs are of a great complexity and have high attenuation levels, mainly because of the required signal splitting operation plus the traversal of a complex switching stage. This makes multi-point support rarely included in commercial OXC nodes. Inspired in previous works in the literature, we propose a novel architecture that combines the best of splitting and tap-and-continue (TaC)...

Efficient traffic trajectory error detection

Zhang, Bo
Fonte: Universidade Rice Publicador: Universidade Rice
Tipo: Thesis; Text Formato: application/pdf
ENG
Relevância na Pesquisa
16.64%
Our recent survey on publicly reported router bugs shows that many router bugs, once triggered, can cause various traffic trajectory errors including traffic deviating from its intended forwarding paths, traffic being mistakenly dropped and unauthorized traffic bypassing packet filters. These traffic trajectory errors are serious problems because they may cause network applications to fail and create security loopholes for network intruders to exploit. Therefore, traffic trajectory errors must be quickly and efficiently detected so that the corrective action can be performed in a timely fashion. Detecting traffic trajectory errors requires the real-time tracking of the control states (e.g., forwarding tables, packet filters) of routers and the scalable monitoring of the actual traffic trajectories in the network. Traffic trajectory errors can then be detected by efficiently comparing the observed traffic trajectories against the intended control states. Making such trajectory error detection efficient and practical for large-scale high speed networks requires us to address many challenges. First, existing traffic trajectory monitoring algorithms require the simultaneously monitoring of all network interfaces in a network for the packets of interest...

Implementation of coarse-grain coherence tracking support in ring-based multiprocessors

Coté, Edmond A.
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado Formato: 2463208 bytes; application/pdf
EN; EN
Relevância na Pesquisa
16.05%
As the number of processors in multiprocessor system-on-chip devices continues to increase, the complexity required for full cache coherence support is often unwarranted for application-specific designs. Bus-based interconnects are no longer suitable for larger-scale systems, and the logic and storage overhead associated with the use of a complex packet-switched network and directory-based cache coherence may be undesirable in single-chip systems. Unidirectional rings are a suitable alternative because they offer many properties favorable to both on-chip implementation and to supporting cache coherence. Reducing the overhead of cache coherence traffic is, however, a concern for these systems. This thesis adapts two filter structures that are based on principles of coarse-grained coherence tracking, and applies them to a ring-based multiprocessor. The first structure tracks the total number of blocks of remote data cached by all processors in a node for a set of regions, where a region is a large area of memory referenced by the upper bits of an address. The second structure records regions of local data whose contents are not cached by any remote node. When used together to filter incoming or outgoing requests, these structures reduce the extent of coherence traffic and limit the transmission of coherent requests to the necessary parts of the system. A complete single-chip multiprocessor system that includes the proposed filters is designed and implemented in programmable logic for this thesis. The system is composed of nodes of bus-based multiprocessors...

Synchronous brain activity across individuals underlies shared psychological perspectives

Lahnakoski, Juha M.; Glerean, Enrico; Jääskeläinen, Iiro P.; Hyönä, Jukka; Hari, Riitta; Sams, Mikko; Nummenmaa, Lauri
Fonte: Academic Press Publicador: Academic Press
Tipo: Artigo de Revista Científica
Publicado em 15/10/2014 EN
Relevância na Pesquisa
26.02%
For successful communication, we need to understand the external world consistently with others. This task requires sufficiently similar cognitive schemas or psychological perspectives that act as filters to guide the selection, interpretation and storage of sensory information, perceptual objects and events. Here we show that when individuals adopt a similar psychological perspective during natural viewing, their brain activity becomes synchronized in specific brain regions. We measured brain activity with functional magnetic resonance imaging (fMRI) from 33 healthy participants who viewed a 10-min movie twice, assuming once a ‘social’ (detective) and once a ‘non-social’ (interior decorator) perspective to the movie events. Pearson's correlation coefficient was used to derive multisubject voxelwise similarity measures (inter-subject correlations; ISCs) of functional MRI data. We used k-nearest-neighbor and support vector machine classifiers as well as a Mantel test on the ISC matrices to reveal brain areas wherein ISC predicted the participants' current perspective. ISC was stronger in several brain regions—most robustly in the parahippocampal gyrus, posterior parietal cortex and lateral occipital cortex—when the participants viewed the movie with similar rather than different perspectives. Synchronization was not explained by differences in visual sampling of the movies...

Strong HIV and hepatitis disclosure norms and frequent risk behaviors among Hungarian drug injectors

Gyarmathy, V. Anna; Neaigus, Alan; Ujhelyi, Eszter; Szabó, Tímea; Rácz, József
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /04/2006 EN
Relevância na Pesquisa
16.05%
Ethnographic interviews and focus groups were conducted (05/2003-01/2004) among injecting drug users (IDUs; n=29) in Budapest, Hungary to assess HIV, Hepatitis B and C (HBV and HCV) related knowledge, norms, attitudes and behaviors. Participants perceived themselves at low risk for infection with HIV but high risk for hepatitis through injection but not sexual exposure. They reported strong disclosure norms for HIV and hepatitis infections, while sexual and injecting risk behaviors were influenced by trust about partners' self-report of infection status. Injecting networks were small, with infrequent syringe sharing among a few close friends. Cookers and drug filters were often shared, and filters were re-used as a backup drug supply. Most sexual relationships were monogamous, where condoms were rarely used. Although participant norms supported HIV/HBV/HCV testing, the lack of available testing facilities was a barrier to getting tested. Strong norms for infection disclosure and for getting tested coexist with engaging in risk behaviors with injecting and sex partners who are close friends. Network interventions among IDUs in Hungary should build on disclosure norms and trust to reduce injecting and sex risk. Testing services should be expanded and access increased so that IDUs can act on and reinforce their norms for testing.

A Filter-Mediated Communication Model for Design Collaboration in Building Construction

Lee, Jaewook; Jeong, Yongwook; Oh, Minho; Hong, Seung Wan
Fonte: Hindawi Publishing Corporation Publicador: Hindawi Publishing Corporation
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.3%
Multidisciplinary collaboration is an important aspect of modern engineering activities, arising from the growing complexity of artifacts whose design and construction require knowledge and skills that exceed the capacities of any one professional. However, current collaboration in the architecture, engineering, and construction industries often fails due to lack of shared understanding between different participants and limitations of their supporting tools. To achieve a high level of shared understanding, this study proposes a filter-mediated communication model. In the proposed model, participants retain their own data in the form most appropriate for their needs with domain-specific filters that transform the neutral representations into semantically rich ones, as needed by the participants. Conversely, the filters can translate semantically rich, domain-specific data into a neutral representation that can be accessed by other domain-specific filters. To validate the feasibility of the proposed model, we computationally implement the filter mechanism and apply it to a hypothetical test case. The result acknowledges that the filter mechanism can let the participants know ahead of time what will be the implications of their proposed actions...

Evidence-Based Practice in PubMed: Are Shared Filters Useful to Health Sciences Academic Users?

Clar, Monique; Dupont, Patrice
Fonte: Université de Montréal Publicador: Université de Montréal
Tipo: Communication, présentation / Paper, Presentation
EN
Relevância na Pesquisa
66.7%
Objectives In April 2010, the Université de Montréal’s Health Sciences Library has implemented shared filters in its institutional PubMed account. Most of these filters are designed to highlight resources for evidence-based practice, such as Clinical Queries, Systematic Reviews and Evidence-based Synopsis. We now want to measure how those filters are perceived and used by our users. Methods For one month, data was gathered through an online questionnaire proposed to users of Université de Montréal’s PubMed account. A print version was also distributed to participants in information literacy workshops given by the health sciences librarians. Respondents were restricted to users affiliated to Université de Montréal’s faculties of Medicine, Dentistry, Veterinary Sciences, Nursing and Pharmacy. Basic user information such as year/program of study or department affiliation was also collected. The questionnaire allowed users to identify the filters they use, assess the relevance of filters, and also suggest new ones. Results Survey results showed that the shared filters of Université de Montreal’s PubMed account were found useful by the majority of respondents. Filters allowing rapid access to secondary resources ranked among the most relevant (Reviews...

Geometrically Intrinsic Nonlinear Recursive Filters I: Algorithms

Darling, R. W. R.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 06/09/1998
Relevância na Pesquisa
25.87%
The Geometrically Intrinsic Nonlinear Recursive Filter, or GI Filter, is designed to estimate an arbitrary continuous-time Markov diffusion process X subject to nonlinear discrete-time observations. The GI Filter is fundamentally different from the much-used Extended Kalman Filter (EKF), and its second-order variants, even in the simplest nonlinear case, in that: (i) It uses a quadratic function of a vector observation to update the state, instead of the linear function used by the EKF. (ii) It is based on deeper geometric principles, which make the GI Filter coordinate-invariant. This implies, for example, that if a linear system were subjected to a nonlinear transformation f of the state-space and analyzed using the GI Filter, the resulting state estimates and conditional variances would be the push-forward under f of the Kalman Filter estimates for the untransformed system - a property which is not shared by the EKF or its second-order variants. The noise covariance of X and the observation covariance themselves induce geometries on state space and observation space, respectively, and associated canonical connections. A sequel to this paper develops stochastic differential geometry results - based on "intrinsic location parameters"...

Entangling Independent Photons by Time Measurement

Halder, Matthaeus; Beveratos, Alexios; Gisin, Nicolas; Scarani, Valerio; Simon, Christoph; Zbinden, Hugo
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 05/04/2007
Relevância na Pesquisa
16.05%
A quantum system composed of two or more subsystems can be in an entangled state, i.e. a state in which the properties of the global system are well defined but the properties of each subsystem are not. Entanglement is at the heart of quantum physics, both for its conceptual foundations and for applications in information processing and quantum communication. Remarkably, entanglement can be "swapped": if one prepares two independent entangled pairs A1-A2 and B1-B2, a joint measurement on A1 and B1 (called a "Bell-State Measurement", BSM) has the effect of projecting A2 and B2 onto an entangled state, although these two particles have never interacted or shared any common past[1,2]. Experiments using twin photons produced by spontaneous parametric down-conversion (SPDC) have already demonstrated entanglement swapping[3-6], but here we present its first realization using continuous wave (CW) sources, as originally proposed[2]. The challenge was to achieve sufficiently sharp synchronization of the photons in the BSM. Using narrow-band filters, the coherence time of the photons that undergo the BSM is significantly increased, exceeding the temporal resolution of the detectors. Hence pulsed sources can be replaced by CW sources, which do not require any synchronization[6...

Camera identification by grouping images from database, based on shared noise patterns

Baar, Teun; van Houten, Wiger; Geradts, Zeno
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.02%
Previous research showed that camera specific noise patterns, so-called PRNU-patterns, are extracted from images and related images could be found. In this particular research the focus is on grouping images from a database, based on a shared noise pattern as an identification method for cameras. Using the method as described in this article, groups of images, created using the same camera, could be linked from a large database of images. Using MATLAB programming, relevant image noise patterns are extracted from images much quicker than common methods by the use of faster noise extraction filters and improvements to reduce the calculation costs. Relating noise patterns, with a correlation above a certain threshold value, can quickly be matched. Hereby, from a database of images, groups of relating images could be linked and the method could be used to scan a large number of images for suspect noise patterns.

Retouched Bloom Filters: Allowing Networked Applications to Flexibly Trade Off False Positives Against False Negatives

Donnet, Benoit; Baynat, Bruno; Friedman, Timur
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
26.24%
Where distributed agents must share voluminous set membership information, Bloom filters provide a compact, though lossy, way for them to do so. Numerous recent networking papers have examined the trade-offs between the bandwidth consumed by the transmission of Bloom filters, and the error rate, which takes the form of false positives, and which rises the more the filters are compressed. In this paper, we introduce the retouched Bloom filter (RBF), an extension that makes the Bloom filter more flexible by permitting the removal of selected false positives at the expense of generating random false negatives. We analytically show that RBFs created through a random process maintain an overall error rate, expressed as a combination of the false positive rate and the false negative rate, that is equal to the false positive rate of the corresponding Bloom filters. We further provide some simple heuristics and improved algorithms that decrease the false positive rate more than than the corresponding increase in the false negative rate, when creating RBFs. Finally, we demonstrate the advantages of an RBF over a Bloom filter in a distributed network topology measurement application, where information about large stop sets must be shared among route tracing monitors.; Comment: This is a new version of the technical reports with improved algorithms and theorical analysis of algorithms

Dynamic wired-wireless architecture for WDM stacking access networks

Puerto-Leguizamón,Gustavo Adolfo; Realpe-Mancipe,Laura Camila; Suárez-Fajardo,Carlos Arturo
Fonte: DYNA Publicador: DYNA
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/12/2014 EN
Relevância na Pesquisa
26.05%
This paper presents a dynamic architecture for convergent wired and wireless access networks in Time Division Multiplexing (TDM) based Passive Optical Network (PON) featuring wavelength stacking. Four wavelengths for wired services carrying 10 Gb/s traffic load, one shared extra reconfigurable wavelength and one wavelength common to all Optical Network Units (ONUs) for the transport of wireless services were launched into a 1:64 splitting ratio PON network. In the ONU, a tunable free spaced Fourier optics based filter selects one of the wavelengths conveying wired services and a tunable Fiber Bragg Grating (FBG) filters out the wavelength carrying the wireless services. In the uplink direction, subcarrier multiplexing (SCM) was used for the combined transport of the wired and wireless signals to the Central Office (CO).