505 resultados para Low pass filters


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The increasing popularity of video consumption from mobile devices requires an effective video coding strategy. To overcome diverse communication networks, video services often need to maintain sustainable quality when the available bandwidth is limited. One of the strategy for a visually-optimised video adaptation is by implementing a region-of-interest (ROI) based scalability, whereby important regions can be encoded at a higher quality while maintaining sufficient quality for the rest of the frame. The result is an improved perceived quality at the same bit rate as normal encoding, which is particularly obvious at the range of lower bit rate. However, because of the difficulties of predicting region-of-interest (ROI) accurately, there is a limited research and development of ROI-based video coding for general videos. In this paper, the phase spectrum quaternion of Fourier Transform (PQFT) method is adopted to determine the ROI. To improve the results of ROI detection, the saliency map from the PQFT is augmented with maps created from high level knowledge of factors that are known to attract human attention. Hence, maps that locate faces and emphasise the centre of the screen are used in combination with the saliency map to determine the ROI. The contribution of this paper lies on the automatic ROI detection technique for coding a low bit rate videos which include the ROI prioritisation technique to give different level of encoding qualities for multiple ROIs, and the evaluation of the proposed automatic ROI detection that is shown to have a close performance to human ROI, based on the eye fixation data.

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Frequent exposure to ultrafine particles (UFP) is associated with detrimental effects on cardiopulmonary function and health. UFP dose and therefore the associated health risk are a factor of exposure frequency, duration, and magnitude of (therefore also proximity to) a UFP emission source. Bicycle commuters using on-road routes during peak traffic times are sharing a microenvironment with high levels of motorised traffic, a major UFP emission source. Inhaled particle counts were measured along popular pre-identified bicycle commute route alterations of low (LOW) and high (HIGH) motorised traffic to the same inner-city destination at peak commute traffic times. During commute, real-time particle number concentration (PNC; mostly in the UFP range) and particle diameter (PD), heart and respiratory rate, geographical location, and meteorological variables were measured. To determine inhaled particle counts, ventilation rate was calculated from heart-rate-ventilation associations, produced from periodic exercise testing. Total mean PNC of LOW (compared to HIGH) was reduced (1.56 x e4 ± 0.38 x e4 versus 3.06 x e4 ± 0.53 x e4 ppcc; p = 0.012). Total estimated ventilation rate did not vary significantly between LOW and HIGH (43 ± 5 versus 46 ± 9 L•min; p = 0.136); however, due to total mean PNC, accumulated inhaled particle counts were 48% lower in LOW, compared to HIGH (7.6 x e8 ± 1.5 x e8 versus 14.6 x e8 ± 1.8 x e8; p = 0.003). For bicycle commuting at peak morning commute times, inhaled particle counts and therefore cardiopulmonary health risk may be substantially reduced by decreasing exposure to motorised traffic, which should be considered by both bicycle commuters and urban planners.

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A simple and effective down-sample algorithm, Peak-Hold-Down-Sample (PHDS) algorithm is developed in this paper to enable a rapid and efficient data transfer in remote condition monitoring applications. The algorithm is particularly useful for high frequency Condition Monitoring (CM) techniques, and for low speed machine applications since the combination of the high sampling frequency and low rotating speed will generally lead to large unwieldy data size. The effectiveness of the algorithm was evaluated and tested on four sets of data in the study. One set of the data was extracted from the condition monitoring signal of a practical industry application. Another set of data was acquired from a low speed machine test rig in the laboratory. The other two sets of data were computer simulated bearing defect signals having either a single or multiple bearing defects. The results disclose that the PHDS algorithm can substantially reduce the size of data while preserving the critical bearing defect information for all the data sets used in this work even when a large down-sample ratio was used (i.e., 500 times down-sampled). In contrast, the down-sample process using existing normal down-sample technique in signal processing eliminates the useful and critical information such as bearing defect frequencies in a signal when the same down-sample ratio was employed. Noise and artificial frequency components were also induced by the normal down-sample technique, thus limits its usefulness for machine condition monitoring applications.

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Recent attention in education within many western contexts has focused on improved outcomes for students, with a particular focus on closing the gap between those who come from disadvantaged backgrounds and the rest of the student population. Much of this attention has supported a set of simplistic solutions to improving scores on high stakes standardized tests. The collateral damage (Nichols & Berliner, 2007) of such responses includes a narrowing of the curriculum, plateaus in gain scores on the tests, and unproductive blame games aimed by the media and politicians at teachers and communities (Nichols & Berliner, 2007; Synder, 2008). Alternative approaches to improving the quality and equity of schooling remain as viable alternatives to these measures. As an example in a recent study of school literacy reform in low SES schools, Luke, Woods and Dooley (2011) argued for the increase of substantive content and intellectual quality of the curriculum as a necessary means to re-engaging middle school students, improving outcomes of schooling and achieving a high quality, high equity system. The MediaClub is an afterschool program for students in years 4 to 7 (9-12 year old) at a primary school in a low SES area of a large Australian city. It is run as part of an Australian Research Council funded research project. The aim of the program has been to provide an opportunity for students to gain expertise in digital technologies and media literacies in an afterschool setting. It was hypothesized that this expertise might then be used to shift the ways of being literate that these students had to call on within classroom teaching and learning events. Each term, there is a different focus on digital media, and information and communication technology (ICT) activities in the MediaClub. The work detailed in this chapter relates to a robotics program presented as one of the modules within this afterschool setting. As part of the program, the participants were challenged to find creative solutions to problems in a constructivist-learning environment.

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This paper evaluates the age-associated changes of resting ventilation of 115 high- and low-altitude Aymara subjects, of whom 61 were from the rural Aymara village of Ventilla situated at an average altitude of 4,200 m and 54 from the rural village of Caranavi situated at an average altitude of 900 m. Comparison of the age patterns of resting ventilation suggests the following conclusions: 1) the resting ventilation (ml/kg/min) of high-altitude natives is markedly higher than that of low-altitude natives; 2) the age decline of ventilation is similar in both lowlanders and highlanders, but the starting point and therefore the age decline are much higher at high altitude; 3) the resting ventilation that characterizes high-altitude Andean natives is developmentally expressed in the same manner as it is at low altitude; and 4) the resting ventilation (ml/kg/min) of Aymara high-altitude natives is between 40–80% lower than that of Tibetans. Am J Phys Anthropol 109:295–301, 1999. © 1999 Wiley-Liss, Inc.

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In most visual mapping applications suited to Autonomous Underwater Vehicles (AUVs), stereo visual odometry (VO) is rarely utilised as a pose estimator as imagery is typically of very low framerate due to energy conservation and data storage requirements. This adversely affects the robustness of a vision-based pose estimator and its ability to generate a smooth trajectory. This paper presents a novel VO pipeline for low-overlap imagery from an AUV that utilises constrained motion and integrates magnetometer data in a bi-objective bundle adjustment stage to achieve low-drift pose estimates over large trajectories. We analyse the performance of a standard stereo VO algorithm and compare the results to the modified vo algorithm. Results are demonstrated in a virtual environment in addition to low-overlap imagery gathered from an AUV. The modified VO algorithm shows significantly improved pose accuracy and performance over trajectories of more than 300m. In addition, dense 3D meshes generated from the visual odometry pipeline are presented as a qualitative output of the solution.

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Volunteering Qld’s Project Creatives continues to explore the critical role creative disciplines and creative people play in providing new models of engagement and action in social change and community work. This article explores three different non-profit organisations that have used collaborative photography to enable locals to empower themselves. Written by Alice Baroni a volunteer with the Education, Research and Policy Unit of Volunteering Qld. Alice is undertaking a PhD at the Queensland University of Technology, exploring (photo) journalism, participatory content creation and community photography in Brazil’s low income suburbs. She is part of the ARC Centre of Excellence for Creative Industries and Innovation, and a Brazilian research group ‘Storytellers and Narratives: Contemporary Journalism’. Two of the initiatives explored in this publication are Viva Favela and Imagens do Povo that are ideologically and physically supported by, respectively, Viva Rio and Observatório de Favelas, based in Rio de Janeiro, Brazil. ‘Favela’ is often translated simply as ‘slum’ or ‘shantytown’, but these terms connote negative characteristics such as shortage, poverty, and deprivation, which end up stigmatising these low-income suburbs. Fotografi Senza Frontiere (FSF) (Photographers Without Borders) is an Italian non-governmental organisation that gathers together a group of photographers who aim to provide youth from extreme regions in Nicaragua, Algeria, Argentina, Panama, Uganda, and Palestine with skills to photograph and document their own reality by establishing permanent photo laboratories. This idea, which is similar to that of Viva Favela and Imagens do Povo, is to enable youth to become professional photographers as a means of self-representation and self-empowerment. Afterwards, students become educators in established photographic labs so as to pass on what they have learnt through FSF’s photographic courses.

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The first representative chemical, structural, and morphological analysis of the solid particles from a single collection surface has been performed. This collection surface sampled the stratosphere between 17 and 19km in altitude in the summer of 1981, and therefore before the 1982 eruptions of El Chichón. A particle collection surface was washed free of all particles with rinses of Freon and hexane, and the resulting wash was directed through a series of vertically stacked Nucleopore filters. The size cutoff for the solid particle collection process in the stratosphere is found to be considerably less than 1 μm. The total stratospheric number density of solid particles larger than 1μm in diameter at the collection time is calculated to be about 2.7×10−1 particles per cubic meter, of which approximately 95% are smaller than 5μm in diameter. Previous classification schemes are expanded to explicitly recognize low atomic number material. With the single exception of the calcium-aluminum-silicate (CAS) spheres all solid particle types show a logarithmic increase in number concentration with decreasing diameter. The aluminum-rich particles are unique in showing bimodal size distributions. In addition, spheres constitute only a minor fraction of the aluminum-rich material. About 2/3 of the particles examined were found to be shards of rhyolitic glass. This abundant volcanic material could not be correlated with any eruption plume known to have vented directly to the stratosphere. The micrometeorite number density calculated from this data set is 5×10−2 micrometeorites per cubic meter of air, an order of magnitude greater than the best previous estimate. At the collection altitude, the maximum collision frequency of solid particles >5μm in average diameter is calculated to be 6.91×10−16 collisions per second, which indicates negligible contamination of extraterrestrial particles in the stratosphere by solid anthropogenic particles.

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Accurate thin-film energy dispersive spectroscopic (EDS) analyses of clays with low-atomic-number (low Z) elements (e.g. Na, Al, Si), presents a challenge to the microscopist not only because of the spatial resolution required, but also because of their susceptibility to electron beam-induced radiation damange and very low X-ray count rates. Most common clays, such as kaolinite, smectite and illite occur as submicrometer crystallites with varying degrees of structural disorder in at least two directions and may have dimensions as small as one or two unit cells along the basal direction. Thus, even clays with relatively large a-b dimenstions (e.g., 100 x 100 nm) may be <5nm in the c-axis direction. For typical conditions in an analytical electron microscope (AEM), this sample thickness gives rise to very poor count rates (<200cps) and necessitates long counting times (>300s) in order to obtain satisfactory statistical precision. Unfortunately, beam damage rates for the common clays are very rapid (<10s in imaging mode) between 100kV and 200kV. With a focussed probe for elemental analyses, the damage rate is exacerbated by a high current density and may result in loss of low-Z elements during data collection and consequent loss of analytical accuracy.

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Background: Vitamin B12 deficiency is prevalent in many countries of origin of refugees. Using a threshold of 5% above which a prevalence of low Vitamin B12 is indicative of a population health problem, we hypothesised that Vitamin B12 deficiency exceeds this threshold among newly-arrived refugees resettling in Australia, and is higher among women due to their increased risk of food insecurity. This paper reports Vitamin B12 levels in a large cohort of newly arrived refugees in five Australian states and territories. Methods: In a cross-sectional descriptive study, we collected Vitamin B12, folate and haematological indices on all refugees(n = 916; response rate 94% of eligible population) who had been in Australia for less than one year, and attended one of the collaborating health services between July 2010 and July 2011. Results: 16.5% of participants had Vitamin B12 deficiency (,150 pmol/L). One-third of participants from Iran and Bhutan, and one-quarter of participants from Afghanistan had Vitamin B12 deficiency. Contrary to our hypothesis, low Vitamin B12 levels were more prevalent in males than females. A higher prevalence of low Vitamin B12 was also reported in older age groups in some countries. The sensitivity of macrocytosis in detecting Vitamin B12 deficiency was only 4.6%. Conclusion: Vitamin B12 deficiency is an important population health issue in newly-arrived refugees from many countries. All newly-arrived refugees should be tested for Vitamin B12 deficiency. Ongoing research should investigate causes,treatment, and ways to mitigate food insecurity, and the contribution of such measures to enhancing the health of the refugee communities.