970 resultados para Wide-Area Measurements
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Federal Highway Administration, Washington, D.C.
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Mode of access: Internet.
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Arguably, the world has become one large pervasive computing environment. Our planet is growing a digital skin of a wide array of sensors, hand-held computers, mobile phones, laptops, web services and publicly accessible web-cams. Often, these devices and services are deployed in groups, forming small communities of interacting devices. Service discovery protocols allow processes executing on each device to discover services offered by other devices within the community. These communities can be linked together to form a wide-area pervasive environment, allowing processes in one p u p tu interact with services in another. However, the costs of communication and the protocols by which this communication is mediated in the wide-area differ from those of intra-group, or local-area, communication. Communication is an expensive operation for small, battery powered devices, but it is less expensive for servem and workstations, which have a constant power supply and 81'e connected to high bandwidth networks. This paper introduces Superstring, a peer to-peer service discovery protocol optimised fur use in the wide-area. Its goals are to minimise computation and memory overhead in the face of large numbers of resources. It achieves this memory and computation scalability by distributing the storage cost of service descriptions and the computation cost of queries over multiple resolvers.
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B-ISDN is a universal network which supports diverse mixes of service, applications and traffic. ATM has been accepted world-wide as the transport technique for future use in B-ISDN. ATM, being a simple packet oriented transfer technique, provides a flexible means for supporting a continuum of transport rates and is efficient due to possible statistical sharing of network resources by multiple users. In order to fully exploit the potential statistical gain, while at the same time provide diverse service and traffic mixes, an efficient traffic control must be designed. Traffic controls which include congestion and flow control are a fundamental necessity to the success and viability of future B-ISDN. Congestion and flow control is difficult in the broadband environment due to the high speed link, the wide area distance, diverse service requirements and diverse traffic characteristics. Most congestion and flow control approaches in conventional packet switched networks are reactive in nature and are not applicable in the B-ISDN environment. In this research, traffic control procedures mainly based on preventive measures for a private ATM-based network are proposed and their performance evaluated. The various traffic controls include CAC, traffic flow enforcement, priority control and an explicit feedback mechanism. These functions operate at call level and cell level. They are carried out distributively by the end terminals, the network access points and the internal elements of the network. During the connection set-up phase, the CAC decides the acceptance or denial of a connection request and allocates bandwidth to the new connection according to three schemes; peak bit rate, statistical rate and average bit rate. The statistical multiplexing rate is based on a `bufferless fluid flow model' which is simple and robust. The allocation of an average bit rate to data traffic at the expense of delay obviously improves the network bandwidth utilisation.
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Human motion monitoring is an important function in numerous applications. In this dissertation, two systems for monitoring motions of multiple human targets in wide-area indoor environments are discussed, both of which use radio frequency (RF) signals to detect, localize, and classify different types of human motion. In the first system, a coherent monostatic multiple-input multiple-output (MIMO) array is used, and a joint spatial-temporal adaptive processing method is developed to resolve micro-Doppler signatures at each location in a wide-area for motion mapping. The downranges are obtained by estimating time-delays from the targets, and the crossranges are obtained by coherently filtering array spatial signals. Motion classification is then applied to each target based on micro-Doppler analysis. In the second system, multiple noncoherent multistatic transmitters (Tx's) and receivers (Rx's) are distributed in a wide-area, and motion mapping is achieved by noncoherently combining bistatic range profiles from multiple Tx-Rx pairs. Also, motion classification is applied to each target by noncoherently combining bistatic micro-Doppler signatures from multiple Tx-Rx pairs. For both systems, simulation and real data results are shown to demonstrate the ability of the proposed methods for monitoring patient repositioning activities for pressure ulcer prevention.
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Flux of siliceous plankton and taxonomic composition of diatom and silicoflagellate assemblages were determined from sediment trap samples collected in coastal upwelling-influenced waters off northern Chile (30°S, CH site) under "normal" or non-El Niño (1993-94) and El Niño conditions (1997-98). In addition, concentration of biogenic opal and siliceous plankton, and diatom and silicoflagellate assemblages preserved in surface sediments are provided for a wide area between 27° and 43°S off Chile. Regardless of the year, winter upwelling determines the maximum production pattern of siliceous microorganisms, with diatoms numerically dominating the biogenic opal flux. During the El Niño year the export is markedly lower: on an annual basis, total mass flux diminished by 60%, and diatom and silicoflagellate export by 75%. Major components of the diatom flora maintain much of their regular seasonal cycle of flux maxima and minima during both sampling periods. Neritic resting spores (RS) of Chaetoceros dominate the diatom flux, mirroring the influence of coastal-upwelled waters at the CH trap site. Occurrence of pelagic diatoms species Fragilariopsis doliolus, members of the Rhizosoleniaceae, Azpeitia spp. and Nitzschia interruptestriata, secondary components of the assemblage, reflects the intermingling of warmer waters of the Subtropical Gyre. Dictyocha messanensis dominates the silicoflagellate association almost year-around, but Distephanus pulchra delivers ca. 60% of its annual production in less than three weeks during the winter peak. The siliceous thanatocoenosis is largely dominated by diatoms, whose assemblage shows significant qualitative and quantitative variations from north to south. Between 27° and 35°S, the dominance of RS Chaetoceros, Thalassionema nitzschioides var. nitzschioides and Skeletonema costatum reflects strong export production associated with occurrence of coastal upwelling. Both highest biogenic opal content and diatom concentration at 35° and 41°-43°S coincide with highest pigment concentrations along the Chilean coast. Predominance of the diatom species Thalassiosira pacifica and T. poro-irregulata, and higher relative contribution of the silicoflagellate Distephanus speculum at 41°-43°S suggest the influence of more nutrient-rich waters and low sea surface temperatures, probably associated with the Antarctic Circumpolar Water.
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Objective: To compare measurements of the upper arm cross-sectional areas (total arm area,arm muscle area, and arm fat area of healthy neonates) as calculated using anthropometry with the values obtained by ultrasonography. Materials and methods: This study was performed on 60 consecutively born healthy neonates: gestational age (mean6SD) 39.661.2 weeks, birth weight 3287.16307.7 g, 27 males (45%) and 33 females (55%). Mid-arm circumference and tricipital skinfold thickness measurements were taken on the left upper mid-arm according to the conventional anthropometric method to calculate total arm area, arm muscle area and arm fat area. The ultrasound evaluation was performed at the same arm location using a Toshiba sonolayer SSA-250AÒ, which allows the calculation of the total arm area, arm muscle area and arm fat area by the number of pixels enclosed in the plotted areas. Statistical analysis: whenever appropriate, parametric and non-parametric tests were used in order to compare measurements of paired samples and of groups of samples. Results: No significant differences between males and females were found in any evaluated measurements, estimated either by anthropometry or by ultrasound. Also the median of total arm area did not differ significantly with either method (P50.337). Although there is evidence of concordance of the total arm area measurements (r50.68, 95% CI: 0.55–0.77) the two methods of measurement differed for arm muscle area and arm fat area. The estimated median of measurements by ultrasound for arm muscle area were significantly lower than those estimated by the anthropometric method, which differed by as much as 111% (P,0.001). The estimated median ultrasound measurement of the arm fat was higher than the anthropometric arm fat area by as much as 31% (P,0.001). Conclusion: Compared with ultrasound measurements using skinfold measurements and mid-arm circumference without further correction may lead to overestimation of the cross-sectional area of muscle and underestimation of the cross-sectional fat area. The correlation between the two methods could be interpreted as an indication for further search of correction factors in the equations.
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Seafloor imagery is a rich source of data for the study of biological and geological processes. Among several applications, still images of the ocean floor can be used to build image composites referred to as photo-mosaics. Photo-mosaics provide a wide-area visual representation of the benthos, and enable applications as diverse as geological surveys, mapping and detection of temporal changes in the morphology of biodiversity. We present an approach for creating globally aligned photo-mosaics using 3D position estimates provided by navigation sensors available in deep water surveys. Without image registration, such navigation data does not provide enough accuracy to produce useful composite images. Results from a challenging data set of the Lucky Strike vent field at the Mid Atlantic Ridge are reported
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Leaf area measurements are required in several agronomical studies. Usually, there is an interest for measurement methods that are simple, quick and that will not destroy the leaf. The objectives of this work were to evaluate leaf area (y), length (l) and width (w) of 20 half-sibling progenies of custard apple tree (Annona squamosa L.), and to fit regression equations of the type y = a + bx, where x = l.w, that will allow y to be estimated based on l and w. The experiment was conducted as random blocks with five replicates and four plants per plot. Five mature leaves were randomly collected from each plant. Leaf area was measured with an automatic measuring device and leaf dimensions were determined with a ruler. All values of b were different from zero. Differences occurred only in 11% of the 190 possible comparison pairs between progenies, with regard to the estimates of b. No differences were observed between progenies with respect to leaf length, width and area. In view of this fact, the equation y = 0.72 x (R² = 0.77) was fitted for all progenies.
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Tämä työ on tehty Fingrid Oyj:lle. Työn tavoitteena oli tutkia, miten reaaliaikaista PMU-mittaustietoa voidaan hyödyntää voimajärjestelmän valvonnassa. Voimajärjestelmän dynaamisia ilmiöitä ovat jännite- ja kulmastabiilius. Työssä tutkittiin voimajärjestelmän kulmastabiiliutta PSS/E-ohjelmalla simuloitujen mittaustulosten perusteella. Fouriermuunnoksen tulokset osoittavat, että huonoiten vaimeneva taajuuskomponentti on 0,3 Hz taajuus. Lisäksi tiedetään, että huonosti vaimeneva taajuuskomponentti rajoittaa siirtokapasiteettia. Voimajärjestelmän stabiiliutta voidaan esittää Wide Area Monitoring -järjestelmien (WAMS) avulla. WAMS perustuu Phasor Measurement -laitteen (PMU) reaaliaikaiseen mittaustekniikkaan. Jännitteen vaihekulman mittaaminen mahdollistaa voimajärjestelmän tilan määrittämisen reaaliajassa. Työssä on esitelty Fingridin käytössä oleva WAMS ja lisäksi esitelty kolmen eri laitetoimittajan WAMS:n rakennetta ja operaattorin käyttöön tarkoitettuja käyttöliittymiä. WAMS:n rakenteet ovat pääpiirteittäin samanlaisia, mutta stabiiliuden visuaalisessa esittämisessä on eroja. PMU -mittaustietoja on mahdollista tuoda käytönvalvontajärjestelmään erillisellä tiedonsiirtoprotokollalla. PMU-mittaustiedon hyödyntäminen käytönvalvontajärjestelmän toimintaaluenäytöllä mahdollistaa verkon tilan esittämisen reaaliajassa. Roottorin kulmastabiilius esitetään Fingridin käytönvalvontajärjestelmässä vaihekulmaerojen avulla ja työssä on esitetty, kuinka vaihekulmaeron arvolla on vaikutus tehonsiirtoon. Vaihekulmaeron arvo kuvaa vian jälkeisen tehoheilahtelun voimakkuutta. PMU-mittaustiedon esittäminen antaa operaattorille selkeämmän kuvan ylläpitää tehonsiirto turvallisella tasolla ja epästabiilin heilahtelun havainnoiminen vähentää suurhäiriön riskiä. Tulevaisuudessa siirtoverkon kehittyessä tarvitaan operaattorin käyttöön myös nopeita stabiilisuutta esittäviä työkaluja.
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Highly crystalline, ultra fine TiO (anatase) having high surface area has been prepared by thermal hydrolysis of titanyl sulphate 2 solution and characterized using B.E.T surface area measurements, XRD and chemical analysis. The dependence of surface area on concentration of staffing solution, temperature of hydrolysis, duration of boiling and calcination temperature were also studied. As the boiling temperature, duration of boiling and calcination temperature increased, the surface area of TiO formed decreased significantly. 2 On increasing calcination temperature, the crystallite size of TiO also increased and gradually the phase transformation to rutile took 2 place. The onset and completion temperatures of rutilation were 700 and 10008C, respectively
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Seafloor imagery is a rich source of data for the study of biological and geological processes. Among several applications, still images of the ocean floor can be used to build image composites referred to as photo-mosaics. Photo-mosaics provide a wide-area visual representation of the benthos, and enable applications as diverse as geological surveys, mapping and detection of temporal changes in the morphology of biodiversity. We present an approach for creating globally aligned photo-mosaics using 3D position estimates provided by navigation sensors available in deep water surveys. Without image registration, such navigation data does not provide enough accuracy to produce useful composite images. Results from a challenging data set of the Lucky Strike vent field at the Mid Atlantic Ridge are reported
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Bismuth titanatc-Bi(4)Ti(3)O(12) (BIT) with wide application in the electronic industry as capacitors, memory devices and sensors is the simplest compound in the Aurivillius family, which consists of (Bi(2)O(2))(2+) sheets alternating with (Bi(2)T(i)3O(10))(2-) perovskite-like layers. The synthesis of more resistive BIT ceramics would be preferable advance in obtaining of well-densified ceramic with small grains randomly oriented to limit the conductivity along the (Bi(2)O(2))(2+) layers. Having in mind that the conventional ceramic route for the synthesis can lead to non-stoichiometry in composition, in consequence of the undesirable loss in bismuth content through volatilization of Bi(2)O(3) at elevated temperature, our efforts were addressed to preparation of BIT by mechanical activation the constituent oxides. The nucleation and phase formation of BIT, crystal structure, microstructure, powder particle size and specific surface area were followed by XRD, Rietveld refinement analysis, thermal analysis, scanning electron microscopy (SEM) and the BET specific surface area measurements. (c) 2005 Elsevier B.V. All rights reserved.
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Traffic particle concentrations show considerable spatial variability within a metropolitan area. We consider latent variable semiparametric regression models for modeling the spatial and temporal variability of black carbon and elemental carbon concentrations in the greater Boston area. Measurements of these pollutants, which are markers of traffic particles, were obtained from several individual exposure studies conducted at specific household locations as well as 15 ambient monitoring sites in the city. The models allow for both flexible, nonlinear effects of covariates and for unexplained spatial and temporal variability in exposure. In addition, the different individual exposure studies recorded different surrogates of traffic particles, with some recording only outdoor concentrations of black or elemental carbon, some recording indoor concentrations of black carbon, and others recording both indoor and outdoor concentrations of black carbon. A joint model for outdoor and indoor exposure that specifies a spatially varying latent variable provides greater spatial coverage in the area of interest. We propose a penalised spline formation of the model that relates to generalised kringing of the latent traffic pollution variable and leads to a natural Bayesian Markov Chain Monte Carlo algorithm for model fitting. We propose methods that allow us to control the degress of freedom of the smoother in a Bayesian framework. Finally, we present results from an analysis that applies the model to data from summer and winter separately