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Different Resolutions (different + resolution)
Selected AbstractsMRMOGA: a new parallel multi-objective evolutionary algorithm based on the use of multiple resolutionsCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 4 2007Antonio López Jaimes Abstract In this paper, we introduce MRMOGA (Multiple Resolution Multi-Objective Genetic Algorithm), a new parallel multi-objective evolutionary algorithm which is based on an injection island approach. This approach is characterized by adopting an encoding of solutions which uses a different resolution for each island. This approach allows us to divide the decision variable space into well-defined overlapped regions to achieve an efficient use of multiple processors. Also, this approach guarantees that the processors only generate solutions within their assigned region. In order to assess the performance of our proposed approach, we compare it to a parallel version of an algorithm that is representative of the state-of-the-art in the area, using standard test functions and performance measures reported in the specialized literature. Our results indicate that our proposed approach is a viable alternative to solve multi-objective optimization problems in parallel, particularly when dealing with large search spaces. Copyright © 2006 John Wiley & Sons, Ltd. [source] Comparing mass-consistent atmospheric moisture budgets on an irregular grid: An Arctic exampleTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 592 2003M. Göber Abstract We present a method to minimize the effects of different resolution and mass imbalance when comparing atmospheric energy and water budgets from different datasets. Sizeable differences between re-analysis- and radiosonde-based atmospheric budgets had been found in earlier studies and it had been suspected that the different resolutions of the datasets strongly contributes to these discrepancies. Furthermore, most studies so far had used mass-imbalanced wind fields, which can lead to serious errors. We balance the wind field by using a variational modification algorithm combined with a finite-element discretization which allows the use of data on a grid defined by the radiosonde network. This method permits the computation of flux divergences in integral form and gives a consistent numerical method to get a mass-balanced wind field with minimum modifications. Applying this method to Arctic radiosonde and re-analysis data on the same grid leads to a better agreement with respect to the horizontal distribution and the mean annual cycle of the moisture flux convergence. The constraint of mass balance on the wind field leads to a greatly reduced and more realistic variability in space and time. However, a systematic difference of about 20% remains between the estimate based on a re-analysis dataset sampled only on the coarse grid of the radiosonde network and an estimate based on the use of the full, fine grid of the re-analysis. These systematic differences can be significantly reduced by creating a simulated radiosonde dataset from the re-analysis with doubled resolution. We undertake an extensive analysis of the uncertainty of the estimates originating from the choices made in the specification of the algorithm. Based solely on radiosonde data, which are likely to result in a low bias, we estimate the net water gain of the Arctic atmosphere as 164 ± 10 mm yr,1 (0.45 ± 0.03 mm d,1) for 1979,93. Copyright © 2003 Royal Meteorological Society. [source] GIS in archaeology,the interface between prospection and excavationARCHAEOLOGICAL PROSPECTION, Issue 3 2004Wolfgang NeubauerArticle first published online: 12 MAY 200 Abstract Archaeological prospection and excavation have the same research objective, namely, the study of the material culture of humans. They investigate the archaeological record but are based on different physical properties and work with different resolution and instrumentation. In addition to the study of literature concerning antique discoveries and the collection and evaluation of surface finds, it is aerial archaeology and geophysical prospection that are the most suitable methods of achieving the intended goal. Aerial photographs provide the archaeologist with a large-scale overview, and digital photogrammetric evaluation provides very detailed topographic maps and orthophotographs of the archaeological structures visible on the surface. These structures appear in various forms, through contrasts in the physical properties between the structures themselves and the material that surrounds them. In geophysical prospection, the contrasts between the physical properties of the archaeological structures and the surrounding material usually can be investigated only in the near-surface or with direct ground contact. These contrasts are not directly visible, however, and must instead be measured and converted into a comprehensible visualization. The prospection methods used in the interpretation process are not significantly different from one to another. Interpretation encompasses the localization and classification of archaeological structures, the analysis of their spatial relationships, as well as the creation of models showing the main stratification at a site. Unlike excavations, through archaeological interpretation of prospection data, various accurate archaeological models of the entire site and the surrounding landscape can be made available rapidly. These models can be used for targeted excavations, so as to further condense the information and to refine the models. If all the data are made available in a geographical information system (GIS), it can be combined and further analysed by the excavator as well as by the prospector. Copyright © 2004 John Wiley & Sons, Ltd. [source] Shrinkability Maps for Content-Aware Video ResizingCOMPUTER GRAPHICS FORUM, Issue 7 2008Yi-Fei Zhang Abstract A novel method is given for content-aware video resizing, i.e. targeting video to a new resolution (which may involve aspect ratio change) from the original. We precompute a per-pixel cumulative shrinkability map which takes into account both the importance of each pixel and the need for continuity in the resized result. (If both x and y resizing are required, two separate shrinkability maps are used, otherwise one suffices). A random walk model is used for efficient offline computation of the shrinkability maps. The latter are stored with the video to create a multi-sized video, which permits arbitrary-sized new versions of the video to be later very efficiently created in real-time, e.g. by a video-on-demand server supplying video streams to multiple devices with different resolutions. These shrinkability maps are highly compressible, so the resulting multi-sized videos are typically less than three times the size of the original compressed video. A scaling function operates on the multi-sized video, to give the new pixel locations in the result, giving a high-quality content-aware resized video. Despite the great efficiency and low storage requirements for our method, we produce results of comparable quality to state-of-the-art methods for content-aware image and video resizing. [source] The evolution of hippocampus volume and brain size in relation to food hoarding in birdsECOLOGY LETTERS, Issue 12 2004László Zsolt Garamszegi Abstract Food-hoarding birds frequently use spatial memory to relocate their caches, thus they may evolve a larger hippocampus in their brain than non-hoarder species. However, previous studies testing for such interspecific relationships provided conflicting results. In addition, food hoarding may be a cognitively complex task involving elaboration of a variety of brain regions, even outside of the hippocampus. Hence, specialization to food hoarding may also result in the enlargement of the overall brain. In a phylogenetic analysis of distantly related birds, we studied the interspecific association between food hoarding and the size of different brain regions, each reflecting different resolutions. After adjusting for allometric effects, the relative volume of the hippocampus and the relative size of the entire brain were each positively related to the degree of food-hoarding specialization, even after controlling for migration and brood parasitism. We also found some significant evidence for the relative volume of the telencephalon being associated with food hoarding, but this relationship was dependent on the approach we used. Hence, neural adaptation to food hoarding may favour the evolution of different brain structures. [source] Performance analysis of different meteorological data and resolutions using MaScOD hydrological modelHYDROLOGICAL PROCESSES, Issue 16 2004Roshan Shrestha Abstract Distributed meteorological data collected from different sources are rarely identical within the same domain of space and time. Discrepancies of these data in magnitude, pattern, and resolution play an important role in hydrological simulation. Using four different sets of distributed meteorological data (from the HUBEX-Intense Observation Period and GAME experimental products at different resolutions), hydrological simulations are conducted through a distributed hydrological model called MaScOD (macro-scale OHyMoS assisted distributed) hydrological model. The model's performance is measured using 12 different indexes. Based on these indexes, a relative normalized score is calculated to evaluate the overall performance of the result from each data set. Three sub-basins of the Huaihe River basin in China, taking the cases at Bengbu (132 350 km2), Wangjiaba (29 844 km2) and Suiping (2093 km2), are used for numerical experiments. This study shows the competence of coarse-resolution meteorological data, the GAME reanalysis 1·25° data, to apply in hydrological simulations of large catchments. However, that data failed to simulate the hydrograph in smaller catchments. The results are significantly improved by including spatial variability at finer resolution in that data. Copyright © 2004 John Wiley & Sons, Ltd. [source] An assessment of the differences between three satellite snow cover mapping techniques,HYDROLOGICAL PROCESSES, Issue 18 2002David Bitner Abstract The National Operational Hydrologic Remote Sensing Center (NOHRSC) of the National Oceanic and Atmospheric Administration's (NOAA's) National Weather Service (NWS) provides daily satellite-derived snow cover maps to support the NWS Hydrologic Services Program covering the coterminous USA and Alaska. This study compared the NOHRSC snow cover maps with new automated snow cover maps produced by the National Environmental Satellite, Data, and Information Service (NESDIS) and the snow cover maps created from the Moderate Resolution Imaging Spectroradiometer (MODIS) imagery. The purpose of this paper is to demonstrate and account for the differences that occur between the three different snow cover mapping techniques. Because each of these snow cover products uses data from different sensors at different resolutions, the data were degraded to the coarsest relevant resolution. In both comparisons, forest canopy density was examined as a possible explanatory factor to account for those differences. NOHRSC snow cover maps were compared with NESDIS snow cover maps for 32 different dates from November 2000 to February 2001. NOHRSC snow cover maps were also compared with MODIS snow cover maps in the Pacific Northwest and the Great Plains for 18 days and 21 days, respectively, between March and June 2001. In the first comparison, where the NOHRSC product (,1 km) was degraded to match the resolution of the NESDIS data (,5 km), the two products showed an average agreement of 96%. Forest canopy density data provided only weak explanation for the differences between the NOHRSC and the NESDIS snow cover maps. In the second comparison, where the MODIS product (,500 m) was degraded to match the resolution of the NOHRSC product for two sample areas, the agreement was 94% in the study area in the Pacific Northwest, and 95% in the study area in the Great Plains. Published in 2002 by John Wiley & Sons, Ltd. [source] Numerical implementation of Aristov,Pukhnachev's formulation for axisymmetric viscous incompressible flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2010N. P. Moshkin Abstract In the present work a finite-difference technique is developed for the implementation of a new method proposed by Aristov and Pukhnachev (Doklady Phys. 2004; 49(2):112,115) for modeling of the axisymmetric viscous incompressible fluid flows. A new function is introduced that is related to the pressure and a system similar to the vorticity/stream function formulation is derived for the cross-flow. This system is coupled to an equation for the azimuthal velocity component. The scheme and the algorithm treat the equations for the cross-flow as an inextricably coupled system, which allows one to satisfy two conditions for the stream function with no condition on the auxiliary function. The issue of singularity of the matrix is tackled by adding a small parameter in the boundary conditions. The scheme is thoroughly validated on grids with different resolutions. The new numerical tool is applied to the Taylor flow between concentric rotating cylinders when the upper and lower lids are allowed to rotate independently from the inner cylinder, while the outer cylinder is held at rest. The phenomenology of this flow is adequately represented by the numerical model, including the hysteresis that takes place near certain specific values of the Reynolds number. Thus, the present results can be construed to demonstrate the viability of the new model. The success can be attributed to the adequate physical nature of the auxiliary function. The proposed technique can be used in the future for in-depth investigations of the bifurcation phenomena in rotating flows. Copyright © 2009 John Wiley & Sons, Ltd. [source] Video compression for multicast environments using spatial scalability and simulcast codingINTERNATIONAL JOURNAL OF IMAGING SYSTEMS AND TECHNOLOGY, Issue 6 2003Wade K. Wan Abstract A common problem with many video transmission applications is the wide range of available bandwidths between the server and different clients. These environments require efficient multicast video service, the capability to transmit and receive the same video sequence at different resolutions. Two approaches to achieve multicast service are scalable coding (dependent bitstream coding) and simulcast coding (independent bitstream coding). One would expect scalable coding to have higher coding efficiency because a scalable coded bitstream can exploit similar information in another bitstream. This reasoning would suggest that multicast implementations should only use scalable coding for maximum coding efficiency. However, this article shows results where simulcast coding has been found to outperform spatial scalability (one type of scalable coding). In this article, methods are described to select between simulcast coding and spatial scalability for multicast video transmission. These techniques can be used to determine the proper multicast coding approach for providing service to clients with different communication links. The methodology described can also be used to construct decision regions to guide more general scenarios or adaptively switch between the two coding approaches. A number of important results were obtained that may be directly applicable to commercial multicast systems. © 2004 Wiley Periodicals, Inc. Int J Imaging Syst Technol 13, 331,340, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ima.10065 [source] Orientational analysis of planar fibre systems observed as a Poisson shot-noise processJOURNAL OF MICROSCOPY, Issue 1 2007SALME KÄRKKÄINEN Summary We consider two-dimensional fibrous materials observed as a digital greyscale image. The problem addressed is to estimate the orientation distribution of unobservable thin fibres from a greyscale image modelled by a planar Poisson shot-noise process. The classical stereological approach is not straightforward, because the point intensities of thin fibres along sampling lines may not be observable. For such cases, Kärkkäinen et al. (2001) suggested the use of scaled variograms determined from grey values along sampling lines in several directions. Their method is based on the assumption that the proportion between the scaled variograms and point intensities in all directions of sampling lines is constant. This assumption is proved to be valid asymptotically for Boolean models and dead leaves models, under some regularity conditions. In this work, we derive the scaled variogram and its approximations for a planar Poisson shot-noise process using the modified Bessel function. In the case of reasonable high resolution of the observed image, the scaled variogram has an approximate functional relation to the point intensity, and in the case of high resolution the relation is proportional. As the obtained relations are approximative, they are tested on simulations. The existing orientation analysis method based on the proportional relation is further experimented on images with different resolutions. The new result, the asymptotic proportionality between the scaled variograms and the point intensities for a Poisson shot-noise process, completes the earlier results for the Boolean models and for the dead leaves models. [source] On the use of the intensity-scale verification technique to assess operational precipitation forecastsMETEOROLOGICAL APPLICATIONS, Issue 1 2008Gabriella Csima Abstract The article describes the attempt to include the intensity-scale technique introduced by Casati et al. (2004) into a set of standardized verifications used in operational centres. The intensity-scale verification approach accounts for the spatial structure of the forecast field and allows the skill to be diagnosed as a function of the scale of the forecast error and intensity of the precipitation events. The intensity-scale method has been used to verify two different resolutions of the European Centre for Medium-Range Weather Forecasts (ECMWF) operational quantitative precipitation forecast (QPF) over France, and to compare the performance of the ECMWF and the Hungarian Meteorological Service operational model (ALADIN) forecasts, run over Hungary. Two case studies have been introduced, which show some interesting insight into the spatial scale of the error. The distribution of daily skill score for an extended period of time is also presented. The intensity-scale technique shows that the forecasts in general exhibit better skill for large-scale events, and lower skill for small-scale and intense events. In the paper, it is mentioned how some of the stringent assumptions on the domain over which the method can be applied, and the availability of the matched forecasts and observations, can limit its usability in an operational environment. Copyright © 2008 Royal Meteorological Society [source] The invariom model and its application: refinement of d,l -serine at different temperatures and resolutionACTA CRYSTALLOGRAPHICA SECTION A, Issue 3 2005B. Dittrich Three X-ray data sets of the same d,l -serine crystal were measured at temperatures of 298, 100 and 20,K. These data were then evaluated using invarioms and the Hansen & Coppens aspherical-atom model. Multipole populations for invarioms, which are pseudoatoms that remain approximately invariant in an intermolecular transfer, were theoretically predicted using different density functional theorem (DFT) basis sets. The invariom parameters were kept fixed and positional and thermal parameters were refined to compare the fitting against the multi-temperature data at different resolutions. The deconvolution of thermal motion and electron density with respect to data resolution was studied by application of the Hirshfeld test. Above a resolution of sin,/,,,,0.55,Ĺ,1, or d,,,0.9,Ĺ, this test was fulfilled. When the Hirshfeld test is fulfilled, a successful modeling of the aspherical electron density with invarioms is achieved, which was proven by Fourier methods. Molecular geometry improves, especially for H atoms, when using the invariom method compared to the independent-atom model, as a comparison with neutron data shows. Based on this example, the general applicability of the invariom concept to organic molecules is proven and the aspherical density modeling of a larger biomacromolecule is within reach. [source] Comparing mass-consistent atmospheric moisture budgets on an irregular grid: An Arctic exampleTHE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 592 2003M. Göber Abstract We present a method to minimize the effects of different resolution and mass imbalance when comparing atmospheric energy and water budgets from different datasets. Sizeable differences between re-analysis- and radiosonde-based atmospheric budgets had been found in earlier studies and it had been suspected that the different resolutions of the datasets strongly contributes to these discrepancies. Furthermore, most studies so far had used mass-imbalanced wind fields, which can lead to serious errors. We balance the wind field by using a variational modification algorithm combined with a finite-element discretization which allows the use of data on a grid defined by the radiosonde network. This method permits the computation of flux divergences in integral form and gives a consistent numerical method to get a mass-balanced wind field with minimum modifications. Applying this method to Arctic radiosonde and re-analysis data on the same grid leads to a better agreement with respect to the horizontal distribution and the mean annual cycle of the moisture flux convergence. The constraint of mass balance on the wind field leads to a greatly reduced and more realistic variability in space and time. However, a systematic difference of about 20% remains between the estimate based on a re-analysis dataset sampled only on the coarse grid of the radiosonde network and an estimate based on the use of the full, fine grid of the re-analysis. These systematic differences can be significantly reduced by creating a simulated radiosonde dataset from the re-analysis with doubled resolution. We undertake an extensive analysis of the uncertainty of the estimates originating from the choices made in the specification of the algorithm. Based solely on radiosonde data, which are likely to result in a low bias, we estimate the net water gain of the Arctic atmosphere as 164 ± 10 mm yr,1 (0.45 ± 0.03 mm d,1) for 1979,93. Copyright © 2003 Royal Meteorological Society. [source] | |||||||||||||||||||