907 resultados para root coverage


Relevância:

20.00% 20.00%

Publicador:

Resumo:

In this paper, sensing coverage by wireless camera-embedded sensor networks (WCSNs), a class of directional sensors is studied. The proposed work facilitates the autonomous tuning of orientation parameters and displacement of camera-sensor nodes in the bounded field of interest (FoI), where the network coverage in terms of every point in the FoI is important. The proposed work is first of its kind to study the problem of maximizing coverage of randomly deployed mobile WCSNs which exploits their mobility. We propose an algorithm uncovered region exploration algorithm (UREA-CS) that can be executed in centralized and distributed modes. Further, the work is extended for two special scenarios: 1) to suit autonomous combing operations after initial random WCSN deployments and 2) to improve the network coverage with occlusions in the FoI. The extensive simulation results show that the performance of UREA-CS is consistent, robust, and versatile to achieve maximum coverage, both in centralized and distributed modes. The centralized and distributed modes are further analyzed with respect to the computational and communicational overheads.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Purpose: A prior image based temporally constrained reconstruction ( PITCR) algorithm was developed for obtaining accurate temperature maps having better volume coverage, and spatial, and temporal resolution than other algorithms for highly undersampled data in magnetic resonance (MR) thermometry. Methods: The proposed PITCR approach is an algorithm that gives weight to the prior image and performs accurate reconstruction in a dynamic imaging environment. The PITCR method is compared with the temporally constrained reconstruction (TCR) algorithm using pork muscle data. Results: The PITCR method provides superior performance compared to the TCR approach with highly undersampled data. The proposed approach is computationally expensive compared to the TCR approach, but this could be overcome by the advantage of reconstructing with fewer measurements. In the case of reconstruction of temperature maps from 16% of fully sampled data, the PITCR approach was 1.57x slower compared to the TCR approach, while the root mean square error using PITCR is 0.784 compared to 2.815 with the TCR scheme. Conclusions: The PITCR approach is able to perform more accurate reconstructions of temperature maps compared to the TCR approach with highly undersampled data in MR guided high intensity focused ultrasound. (C) 2015 American Association of Physicists in Medicine.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The arc-root attachment on the anode surface of a dc non-transferred arc plasma torch has been successfully observed using a novel approach. A specially designed copper mirror with a boron nitride film coated on its surface central-region is employed to avoid the effect of intensive light emitted from the arc column upon the observation of weakly luminous arc root. It is found that the arc-root attachment is diffusive on the anode surface of the argon plasma torch, while constricted arc roots often occur when hydrogen or nitrogen is added into argon as the plasma-forming gas.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Arc root motions in generating dc argon-hydrogen plasma at reduced pressure are optically observed using a high-speed video camera. The time resolved angular position of the arc root attachment point is measured and analysed. The arc root movement is characterized as a chaotic and jumping motion along the circular direction on the anode surface.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Arc root motion on the anode surface of a dc non-transferred plasma torch was observed. Adding hydrogen changes the arc root attachment from a diffused type to a constricted type, and the arc root of Ar-H-2 plasma suddenly,jumps from one spot to another irregularly. Images of the arc root motions taken by a high-speed video camera are presented.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Resumen: Empleando la teoría de la “estructura comunitaria”, un muestreo de diarios principales en 28 ciudades grandes en Estados Unidos examina la cobertura del tema “El manejo de contaminación de agua y acceso a agua potable”. Mediante el análisis de todos los artículos de más de 250 palabras publicados a través de diez años entre 01/01/2001 y 01/01/2011 (339 artículos), se compararon sistemáticamente características comunitarias y el “Vector Mediático” de Pollock (combinando en un valor dos medidas de contenido: la “prominencia” de un artículo en un periódico con la orientación o tono). Cobertura “favorable”, que apoya la mayor ayuda gubernamental para mejorar el abastecimiento de agua potable, fue vinculada con medidas de “los interesados”, por ejemplo, con el porcentaje de hispanos (r de Pearson = .349, p = .04). El análisis de las medidas y su regresión reveló dos medidas significativas asociadas con apoyo para manejo gubernamental por agua potable: porcentaje de hispanos (12.2% de la varianza), y con porcentaje de ciudadanos de 18-24 años, 16.7%. Inesperadamente, la cobertura de manejo gubernamental para mejorar las existencias de agua potable no fue vinculado ni con medidas de “vulnerabilidad” (pobreza, desempleo) ni con medidas de “estabilidad” (educación, ingreso).

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Results observed experimentally are presented, about the DC arc plasma jets and their arc-root behaviour generated at reduced gas pressure without or with an applied magnetic field. Pure argon, argon-hydrogen or argon- nitrogen mixture was used as the plasma-forming gas. A specially designed copper mirror was used for a better observation of the arc-root behaviour on the anode surface of the DC non-transferred arc plasma torch. It was found that in the cases without an applied magnetic field, the laminar plasma jets were stable and approximately axisymmetrical. The arc-root attachment on the anode surface was completely diffusive when argon was used as the plasma-forming gas, while the arc-root attachment often became constrictive when hydrogen or nitrogen was added into the argon. As an external magnetic field was applied, the arc root tended to rotate along the anode surface of the non-transferred arc plasma torch.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Experimentally observed, results are presented for the DCarcplasmajets and theirarc-rootbehaviors generated atreduced gas pressure and without or with an' applied magnetic field. Pure argon, argon -hydrogen or argon-nitrogen mixture is used as the plasma-forming gas. A specially designed copper mirror is constructed and used for better observing the arc-root behavior on the anode surface of the DC non-transferred arcplasma torch. It is shown that for the cases without applied magnetic field, the laminar plasmajets are stable and approximately axisymmetrical. The arc-root attachment on the anode surface is completely diffusive when argon is used as the plasma-forming gas, while the arc-root attachment often becomes constrictive when hydrogen or nitrogen is added into the argon. When an external magnetic field is applied, the arcroot tends to rotate along the anode surface of the non-transferred arcplasma torch.