Uma janela tropical: análise do desempenho luminoso de ambientes com aberturas sombreadas para o clima de Natal/RN

This master thesis introduces assessment procedures of daylighting performance in office rooms with shaded opening, recommendations for Natal-RN (Latitude 05,47' S, Longitude 35,11' W). The studies assume the need of window exterior shading in hot and humid climate buildings. The daylighting performance analyses are based on simulated results for three levels of illuminance (300,500 e 1000 lux) between 08h00 e 16h00, in rooms with 2,80 m height, 6 m large and 4 m, 6 m e 8 m depths, with a centered single opening, window wall ratio (20%, 40% e 60%), four orientations (North, East, South and West), and two types of sky (clear and partially cloudy). The sky characteristics were statistically determined based on hourly data from INPE-CRN solar and daylighting weather station. The lighting performance is resulted from dynamic computer simulation of 72 models using Troplux 3.12. The simulation results were assessed using a new parameter to quantify the use of interior daylighting, the useful percentage of daylight (PULN), which corresponds to the time fraction with satisfactory light, in accordance with the illuminance design. The passive zone depths are defined based on the PULN. Despite the failures of illuminance data from the weather station, the analyses ratified the high potential of daylighting for shaded rooms. The most influential variables on the lighting performance are the opening size and the illuminance of design, while the orientation is a little influential

Uma janela tropical: análise do desempenho luminoso de ambientes com aberturas sombreadas para o clima de Natal/RN

This master thesis introduces assessment procedures of daylighting performance in office rooms with shaded opening, recommendations for Natal-RN (Latitude 05,47' S, Longitude 35,11' W). The studies assume the need of window exterior shading in hot and humid climate buildings. The daylighting performance analyses are based on simulated results for three levels of illuminance (300,500 e 1000 lux) between 08h00 e 16h00, in rooms with 2,80 m height, 6 m large and 4 m, 6 m e 8 m depths, with a centered single opening, window wall ratio (20%, 40% e 60%), four orientations (North, East, South and West), and two types of sky (clear and partially cloudy). The sky characteristics were statistically determined based on hourly data from INPE-CRN solar and daylighting weather station. The lighting performance is resulted from dynamic computer simulation of 72 models using Troplux 3.12. The simulation results were assessed using a new parameter to quantify the use of interior daylighting, the useful percentage of daylight (PULN), which corresponds to the time fraction with satisfactory light, in accordance with the illuminance design. The passive zone depths are defined based on the PULN. Despite the failures of illuminance data from the weather station, the analyses ratified the high potential of daylighting for shaded rooms. The most influential variables on the lighting performance are the opening size and the illuminance of design, while the orientation is a little influential

Uma janela tropical: análise do desempenho luminoso de ambientes com aberturas sombreadas para o clima de Natal/RN

This master thesis introduces assessment procedures of daylighting performance in office rooms with shaded opening, recommendations for Natal-RN (Latitude 05,47' S, Longitude 35,11' W). The studies assume the need of window exterior shading in hot and humid climate buildings. The daylighting performance analyses are based on simulated results for three levels of illuminance (300,500 e 1000 lux) between 08h00 e 16h00, in rooms with 2,80 m height, 6 m large and 4 m, 6 m e 8 m depths, with a centered single opening, window wall ratio (20%, 40% e 60%), four orientations (North, East, South and West), and two types of sky (clear and partially cloudy). The sky characteristics were statistically determined based on hourly data from INPE-CRN solar and daylighting weather station. The lighting performance is resulted from dynamic computer simulation of 72 models using Troplux 3.12. The simulation results were assessed using a new parameter to quantify the use of interior daylighting, the useful percentage of daylight (PULN), which corresponds to the time fraction with satisfactory light, in accordance with the illuminance design. The passive zone depths are defined based on the PULN. Despite the failures of illuminance data from the weather station, the analyses ratified the high potential of daylighting for shaded rooms. The most influential variables on the lighting performance are the opening size and the illuminance of design, while the orientation is a little influential

Feature Extraction from Whole-Sky Ground-Based Images for Cloud-Type Recognition

Several features that can be extracted from digital images of the sky and that can be useful for cloud-type classification of such images are presented. Some features are statistical measurements of image texture, some are based on the Fourier transform of the image and, finally, others are computed from the image where cloudy pixels are distinguished from clear-sky pixels. The use of the most suitable features in an automatic classification algorithm is also shown and discussed. Both the features and the classifier are developed over images taken by two different camera devices, namely, a total sky imager (TSI) and a whole sky imager (WSC), which are placed in two different areas of the world (Toowoomba, Australia; and Girona, Spain, respectively). The performance of the classifier is assessed by comparing its image classification with an a priori classification carried out by visual inspection of more than 200 images from each camera. The index of agreement is 76% when five different sky conditions are considered: clear, low cumuliform clouds, stratiform clouds (overcast), cirriform clouds, and mottled clouds (altocumulus, cirrocumulus). Discussion on the future directions of this research is also presented, regarding both the use of other features and the use of other classification techniques

A catalog of HI-selected galaxies from the south celestial cap region of sky

The first deep catalog of the H I Parkes All Sky Survey (HIPASS) is presented, covering the south celestial cap (SCC) region. The SCC area is similar to2400 deg(2) and covers delta < -62&DEG;. The average rms noise for the survey is 13 mJy beam(-1). Five hundred thirty-six galaxies have been cataloged according to their neutral hydrogen content, including 114 galaxies that have no previous cataloged optical counterpart. This is the largest sample of galaxies from a blind H I survey to date. Most galaxies in optically unobscured regions of sky have a visible optical counterpart; however, there is a small population of low-velocity H I clouds without visible optical counterparts whose origins and significance are unclear. The rms accuracy of the HIPASS positions is found to be 1.'9. The H I mass range of galaxies detected is from &SIM;10(6) to &SIM;10(11) M-.. There are a large number of late-type spiral galaxies in the SCC sample (66%), compared with 30% for optically selected galaxies from the same region in the NASA Extragalactic Database. The average ratio of H I mass to B luminosity of the sample increases according to optical type, from 1.8 M-./L-. for early types to 3.2 M-./L-. for late-type galaxies. The H I-detected galaxies tend to follow the large-scale structure traced by galaxies found in optical surveys. From the number of galaxies detected in this region of sky, we predict the full HIPASS catalog will contain &SIM;5000 galaxies, to a peak flux density limit of &SIM;39 mJy (3 σ), although this may be a conservative estimate as two large voids are present in the region. The H I mass function for this catalog is presented in a subsequent paper.

Sky Spike

Combined media on photographic paper. 87" x 40"

Using a Parameterization of a Radiative Transfer Model to Build High-Resolution Maps of Typical Clear-Sky UV Index in Catalonia, Spain

To perform a climatic analysis of the annual UV index (UVI) variations in Catalonia, Spain (northeast of the Iberian Peninsula), a new simple parameterization scheme is presented based on a multilayer radiative transfer model. The parameterization performs fast UVI calculations for a wide range of cloudless and snow-free situations and can be applied anywhere. The following parameters are considered: solar zenith angle, total ozone column, altitude, aerosol optical depth, and single-scattering albedo. A sensitivity analysis is presented to justify this choice with special attention to aerosol information. Comparisons with the base model show good agreement, most of all for the most common cases, giving an absolute error within 0.2 in the UVI for a wide range of cases considered. Two tests are done to show the performance of the parameterization against UVI measurements. One uses data from a high-quality spectroradiometer from Lauder, New Zealand [45.04°S, 169.684°E, 370 m above mean sea level (MSL)], where there is a low presence of aerosols. The other uses data from a Robertson–Berger-type meter from Girona, Spain (41.97°N, 2.82°E, 100 m MSL), where there is more aerosol load and where it has been possible to study the effect of aerosol information on the model versus measurement comparison. The parameterization is applied to a climatic analysis of the annual UVI variation in Catalonia, showing the contributions of solar zenith angle, ozone, and aerosols. High-resolution seasonal maps of typical UV index values in Catalonia are presented

Retrieving Cloud Characteristics from Ground-Based Daytime Color All-Sky Images

A discussion is presented of daytime sky imaging and techniques that may be applied to the analysis of full-color sky images to infer cloud macrophysical properties. Descriptions of two different types of skyimaging systems developed by the authors are presented, one of which has been developed into a commercially available instrument. Retrievals of fractional sky cover from automated processing methods are compared to human retrievals, both from direct observations and visual analyses of sky images. Although some uncertainty exists in fractional sky cover retrievals from sky images, this uncertainty is no greater than that attached to human observations for the commercially available sky-imager retrievals. Thus, the application of automatic digital image processing techniques on sky images is a useful method to complement, or even replace, traditional human observations of sky cover and, potentially, cloud type. Additionally, the possibilities for inferring other cloud parameters such as cloud brokenness and solar obstruction further enhance the usefulness of sky imagers

Aerosol absorption over the clear-sky oceans deduced from POLDER-1 and AERONET observations

We estimate aerosol absorption over the clear-sky oceans using aerosol geophysical products from POLDER-1 space measurements and absorption properties from ground-based AERONET measurements. Our best estimate is 2.5 Wm-2 averaged over the 8-month lifetime of POLDER-1. Low and high absorption estimates are 2.2 and 3.1 Wm-2 based on the variability in aerosol single scattering albedo observed by AERONET. Main sources of uncertainties are the discrimation of the aerosol type from satellite measurements, and potential clear-sky bias induced by the cloud-screening procedure.

A simplified approach for Chaplygin-type cosmologies

A new class of accelerating cosmological models driven by a one-parameter version of the general Chaplygin-type equation of state is proposed. The simplified version is naturally obtained from causality considerations with basis on the adiabatic sound speed vs plus the observed accelerating stage of the universe. We show that very stringent constraints on the unique free parameter a describing the simplified Chaplygin model can be obtained from a joint analysis involving the latest SNe type la data and the recent Sloan Digital Sky Survey measurement of baryon acoustic oscillations (BAO). In our analysis we have considered separately the SNe type la gold sample measured by [A.G. Riess et al.. Astrophys. J. 607 (2004) 665] and the supernova legacy survey (SNLS) from [P. Astier et al., Astron. Astrophys. 447 (2006) 31]. At 95.4% (c.l.), we find for BAO + gold sample, 0.91 <= alpha <= 1.0 and Omega(m) = 0.28(-0.048)(+0.043) while BAO + SNLS analysis provides 0.94 <= alpha <= 1.0 and Omega(m) = 0.27(-0.045)(+0.048). (C) 2008 Elsevier B.V. All rights reserved.

Extracting evolutionary information from the spectral decomposition of early-type galaxies.

Holding the major share of stellar mass in galaxies and being also old and passively evolving, early-type galaxies (ETGs) are the primary probes in investigating these various evolution scenarios, as well as being useful means to provide insights on cosmological parameters. In this thesis work I focused specifically on ETGs and on their capability in constraining galaxy formation and evolution; in particular, the principal aims were to derive some of the ETGs evolutionary parameters, such as age, metallicity and star formation history (SFH) and to study their age-redshift and mass-age relations. In order to infer galaxy physical parameters, I used the public code STARLIGHT: this program provides a best fit to the observed spectrum from a combination of many theoretical models defined in user-made libraries. the comparison between the output and input light-weighted ages shows a good agreement starting from SNRs of ∼ 10, with a bias of ∼ 2.2% and a dispersion 3%. Furthermore, also metallicities and SFHs are well reproduced. In the second part of the thesis I performed an analysis on real data, starting from Sloan Digital Sky Survey (SDSS) spectra. I found that galaxies get older with cosmic time and with increasing mass (for a fixed redshift bin); absolute light-weighted ages, instead, result independent from the fitting parameters or the synthetic models used. Metallicities, instead, are very similar from each other and clearly consistent with the ones derived from the Lick indices. The predicted SFH indicates the presence of a double burst of star formation. Velocity dispersions and extinctiona are also well constrained, following the expected behaviours. As a further step, I also fitted single SDSS spectra (with SNR∼ 20), to verify that stacked spectra gave the same results without introducing any bias: this is an important check, if one wants to apply the method at higher z, where stacked spectra are necessary to increase the SNR. Our upcoming aim is to adopt this approach also on galaxy spectra obtained from higher redshift Surveys, such as BOSS (z ∼ 0.5), zCOSMOS (z 1), K20 (z ∼ 1), GMASS (z ∼ 1.5) and, eventually, Euclid (z 2). Indeed, I am currently carrying on a preliminary study to estabilish the applicability of the method to lower resolution, as well as higher redshift (z 2) spectra, just like the Euclid ones.

High life in the sky? Mortality by floor of residence in Switzerland

Living in high-rise buildings could influence the health of residents. Previous studies focused on structural features of high-rise buildings or characteristics of their neighbourhoods, ignoring differences within buildings in socio-economic position or health outcomes. We examined mortality by floor of residence in the Swiss National Cohort, a longitudinal study based on the linkage of December 2000 census with mortality and emigration records 2001-2008. Analyses were based on 1.5 million people living in buildings with four or more floors and 142,390 deaths recorded during 11.4 million person-years of follow-up. Cox models were adjusted for age, sex, civil status, nationality, language, religion, education, professional status, type of household and crowding. The rent per m² increased with higher floors and the number of persons per room decreased. Mortality rates decreased with increasing floors: hazard ratios comparing the ground floor with the eighth floor and above were 1.22 [95% confidence interval (CI) 1.15-1.28] for all causes, 1.40 (95% CI 1.11-1.77) for respiratory diseases, 1.35 (95% CI 1.22-1.49) for cardiovascular diseases and 1.22 (95% CI 0.99-1.50) for lung cancer, but 0.41 (95% CI 0.17-0.98) for suicide by jumping from a high place. There was no association with suicide by any means (hazard ratio 0.81; 95% CI 0.57-1.15). We conclude that in Switzerland all-cause and cause-specific mortality varies across floors of residence among people living in high-rise buildings. Gradients in mortality suggest that floor of residence captures residual socioeconomic stratification and is likely to be mediated by behavioural (e.g. physical activity), and environmental exposures, and access to a method of suicide.

Cloud observations in Switzerland using hemispherical sky cameras

We present observations of total cloud cover and cloud type classification results from a sky camera network comprising four stations in Switzerland. In a comprehensive intercomparison study, records of total cloud cover from the sky camera, long-wave radiation observations, Meteosat, ceilometer, and visual observations were compared. Total cloud cover from the sky camera was in 65–85% of cases within ±1 okta with respect to the other methods. The sky camera overestimates cloudiness with respect to the other automatic techniques on average by up to 1.1 ± 2.8 oktas but underestimates it by 0.8 ± 1.9 oktas compared to the human observer. However, the bias depends on the cloudiness and therefore needs to be considered when records from various observational techniques are being homogenized. Cloud type classification was conducted using the k-Nearest Neighbor classifier in combination with a set of color and textural features. In addition, a radiative feature was introduced which improved the discrimination by up to 10%. The performance of the algorithm mainly depends on the atmospheric conditions, site-specific characteristics, the randomness of the selected images, and possible visual misclassifications: The mean success rate was 80–90% when the image only contained a single cloud class but dropped to 50–70% if the test images were completely randomly selected and multiple cloud classes occurred in the images.

A spectroscopy study of nearby late-type stars, possible members of stellar kinematic groups

Context. Nearby late-type stars are excellent targets for seeking young objects in stellar associations and moving groups. The origin of these structures is still misunderstood, and lists of moving group members often change with time and also from author to author. Most members of these groups have been identified by means of kinematic criteria, leading to an important contamination of previous lists by old field stars. Aims. We attempt to identify unambiguous moving group members among a sample of nearby-late type stars by studying their kinematics, lithium abundance, chromospheric activity, and other age-related properties. Methods. High-resolution echelle spectra (R ~ 57 000) of a sample of nearby late-type stars are used to derive accurate radial velocities that are combined with the precise Hipparcos parallaxes and proper motions to compute galactic-spatial velocity components. Stars are classified as possible members of the classical moving groups according to their kinematics. The spectra are also used to study several age-related properties for young late-type stars, i.e., the equivalent width of the lithium Li i 6707.8 Å line or the R'_HK index. Additional information like X-ray fluxes from the ROSAT All-Sky Survey or the presence of debris discs is also taken into account. The different age estimators are compared and the moving group membership of the kinematically selected candidates are discussed. Results. From a total list of 405 nearby stars, 102 have been classified as moving group candidates according to their kinematics. i.e., only ~25.2% of the sample. The number reduces when age estimates are considered, and only 26 moving group candidates (25.5% of the 102 candidates) have ages in agreement with the star having the same age as an MG member.

Recherche et analyse d'étoiles naines blanches chimiquement stratiées dans le Sloan Digital Sky Survey

Ce mémoire présente une recherche détaillée et une analyse des étoiles naines blanches hybrides chimiquement stratifiées dans le Sloan Digital Sky Survey (SDSS). Une seule étoile stratifiée, PG 1305-017, était connue avant notre recherche. L'objectif principal est de confirmer l'existence de plusieurs nouvelles étoiles stratifiées. Pour ce faire, il a fallu dans un premier temps développer une nouvelle génération de modèles d'atmosphère à partir de ceux de Bergeron et al. (1991) et Tremblay & Bergeron (2009). Nous y avons ajouté l'opacité de toutes les raies d'hélium et les calculs nécessaires pour tenir compte de la stratification chimique de l'atmosphère, où une mince quantité d’hydrogène flotte en équilibre diffusif au-dessus d’une enveloppe massive d’hélium. En parallèle, nous avons aussi calculé des modèles standards, chimiquement homogènes. Ensuite, nous avons sélectionné des naines blanches chaudes (Teff > 30,000 K) de type spectral hybride (traces d'hélium et d'hydrogène) parmi les ~38,000 naines blanches répertoriées dans le SDSS. Un total de 52 spectres d'étoile a été retenu dans notre échantillon final. La technique spectroscopique, c'est-à-dire l'ajustement des raies spectrales des modèles sur un spectre observé, a été appliquée à toutes les étoiles de notre échantillon. Nous avons ainsi mesuré la température effective, la gravité de surface et la composition chimique de l'atmosphère de ces étoiles. Par l'ajustement simultané de modèles stratifiés et homogènes, nous avons aussi pu déterminer si les étoiles étaient stratifiées ou non. Nous identifions ainsi 14 naines blanches stratifiées. Nous tirons de ces résultats plusieurs conclusions sur les processus physiques expliquant la présence d'hélium dans l'atmosphère.