Cryogenic mirror analysis

Due to extraordinary distances scanned by modern telescopes, optical surfaces in such telescopes must be manufactured to unimaginable standards of perfection of a few thousandths of a centimeter. The detection of imperfections of less than 1/20 of a wavelength of light, for application in the building of the mirror for the Space Infrared Telescope Facility, was undertaken. Because the mirror must be kept very cold while in space, another factor comes into effect: cryogenics. The process to test a specific morror under cryogenic conditions is described; including the follow-up analysis accomplished through computer work. To better illustrate the process and analysis, a Pyrex Hex-Core mirror is followed through the process from the laser interferometry in the lab, to computer analysis via a computer program called FRINGE. This analysis via FRINGE is detailed

Impact of Climate Change on the Design Parameters of Heating, Ventilation and Air Conditioning Systems for Manned Spacecraft

Climatic design information has been published for several locations in the world by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) but there has not been data for Nigerian cities in these publications. Therefore, this study was embarked upon to bridge the gap in knowledge. The study of impact of climate change on the design parameters of Heating, Ventilation and Air Conditioning (HVAC) systems for spacecraft cabin environment is presented with particular focus on Ikeja-Lagos, Nigeria. Firstly, the characteristics climate parameters such as outdoor dry-bulb temperature, coincident wet-bulb temperature, relative humidity, pressures, air composition, among others as it affects manned spacecraft were discussed. The data for climatic parameters for Ikeja-Lagos, Nigeria, for a period of fifteen years (1995-2009) were obtained from Nigerian Meteorological Agency (NIMET), Oshodi-Lagos. Statistical data and Microsoft excel were used for evaluation of variation trends of the climate parameters for departure city. This is very important in determining thermal human comfort in spacecrafts on ascent. Results obtained from this study are hereby presented. The Ikeja-Lagos dry-bulb temperature average results obtained were 33.81°C, 32.98°C, 32.3°C, 22.1°C, 21.19°C, 20.43°C, 23.84°C and 31.65oC.at 0.4%, 1.0%, 2.0%, 97.5%, 99.0%, 99.6%, median of extreme lows and median of extreme highs, respectively. The Ikeja-Lagos relative humidity average results were 116.3, 112.65, 109.14, 99.83 and 49.42 at 0.4%, 1% and 2.0% occurrence as well as at median of extreme highs and median of extreme lows, respectively. Ikeja-Lagos had mean coincident dry bulb temperature of 33.81°C and 32.98°C at 0.4% and 1% percentile respectively. The dry bulb temperature for Ikeja-Lagos was determined to be an average range from 20.43°C to 22.1°C between January to December, in the period of 1995-2009, at 97.5% 99% and 99.6% percentile respectively. These results provide values of design parameters which are useful in the design of HVAC for space crafts with climate change adequately taken into consideration as it applies to Ikeja-Lagos, Nigeri

Alternative to the Conventional Heating and Cooling Systems in Public Buildings

The paper presents an alternative system for heating and cooling in public buildings. The system was designed for the retrofitted building of the Slovene Ethnographic Museum (SEM) where it was also extensively tested. The installed system includes radiant wall mounted panels for heating and cooling, localized automated tangential fans for cooling and ventilation and a centralized building management system for the regulation and supervision of the performance. The efficiency of the system was thoroughly investigated through a series of experiments conducted prior to the renovation of the building as well as after the museum was put into service. The application of the described system resulted in substantial reduction of energy consumption, better internal thermal conditions and lower investment costs for the Heating, Ventilation and Air Conditioning (HVAC) system of the entire building. (C)2010 Journal of Mechanical Engineering. All rights reserved

Using Photovoltaics to Power Electrochemical Chloride Extraction from Concrete

Corrosion of embedded steel in reinforced concrete (RC) is a world-wide problem, that reduces structural performance and lifespan. Chloride attack may be a result of seawater, de-icing salts or contaminated admixtures, brought on by ingress of chlorides into the concrete. Electrochemical Chloride Extraction (ECE) is a non-destructive treatment for contaminated RC structures, that due to uncertainty of treatment times and applied current densities, is only 50% effective. It is often diesel powered has an environmental impact and often very costly due to the long treatment times. To improve the efficiency of ECE the influences of concrete resistance, cement type and duration of treatment have been investigated in an experimental programme. The use of Photovoltaic (PV) panels to improve the efficiency of ECE is presented which replace fossil fuels as a power source enabling a more environmentally sustainable treatment. These findings will increase the life span of vital infrastructure and reduce expensive ongoing repairs with decreased traffic congestion and inconveniences associated with bridge repairs

Why is it so difficult to represent stably stratified conditions in numerical weather prediction (NWP) models?

In the 1990s, scientists at European Centre for Medium-Range Weather Forecasts (ECMWF) suggested that artificially enhancing turbulent diffusion in stable conditions improves the representation of two important aspects of weather forecasts, i.e., near-surface temperatures and synoptic cyclones. Since then, this practice has often been used for tuning the large-scale performance of operational numerical weather prediction (NWP) models, although it is widely recognized to be detrimental for an accurate representation of stable boundary layers. Here we investigate why, 20 years on, such a compromise is still needed in the ECMWF model. We find that reduced turbulent diffusion in stable conditions improves the representation of winds in stable boundary layers, but it deteriorates the large-scale flow and the near-surface temperatures. This suggests that enhanced diffusion is still needed to compensate for errors caused by other poorly represented processes. Among these, we identify the orographic drag, which influences the large-scale flow in a similar way to the turbulence closure for stable conditions, and the strength of the land-atmosphere coupling, which partially controls the near-surface temperatures. We also take a closer look at the relationship between the turbulence closure in stable conditions and the large-scale flow, which was not investigated in detail with a global NWP model. We demonstrate that the turbulent diffusion in stable conditions affects the large-scale flow by modulating not only the strength of synoptic cyclones and anticyclones, but also the amplitude of the planetary-scale standing waves

SOARNET, Deep Learning Thermal Detection For Free Flight

Thermals are regions of rising hot air formed on the ground through the warming of the surface by the sun. Thermals are commonly used by birds and glider pilots to extend flight duration, increase cross-country distance, and conserve energy. This kind of powerless flight using natural sources of lift is called soaring. Once a thermal is encountered, the pilot flies in circles to keep within the thermal, so gaining altitude before flying off to the next thermal and towards the destination. A single thermal can net a pilot thousands of feet of elevation gain, however estimating thermal locations is not an easy task. Pilots look for different indicators: color variation on the ground because the difference in the amount of heat absorbed by the ground varies based on the color/composition, birds circling in an area gaining lift, and certain types of cloud formations (cumulus clouds). The above methods are not always reliable enough and pilots study the weather for thermals by estimating solar heating of the ground using cloud cover and time of year and the lapse rate and dew point of the troposphere. In this paper, we present a Machine Learning based solution for assisting in forecasting thermals. We created a custom dataset using flight data recorded and uploaded to public databases by soaring pilots. We determine where and when the pilot encountered thermals to pull weather and satellite images corresponding to the location and time of the flight. Using this dataset we train an algorithm to automatically predict the location of thermals given as input the current weather conditions and terrain information obtained from Google Earth Engine and thermal regions encountered as truth labels. We were able to converge very well on the training and validation set, proving our method with around a 0.98 F1 score. These results indicate success in creating a custom dataset and a powerful neural network with the necessity of bolstering our custom dataset

Exploring Extended Radio Galaxies with LOFAR

Extended radio sources are an important minority population in modern, deep radio surveys because they enable detailed investigation of the physics governing radio-emitting regions such as active galaxies and their environments. The Low-frequency array (LOFAR) Two-metre Sky Survey (LoTSS), at 150 MHz, is the largest radio survey to date in terms of numbers of sources and data volume, and is sensitive to both compact and extended emission, making it ideal for the study of extended radio sources. Cross-identification of radio sources with optical host galaxies is challenging for this extended population, due to their morphological complexity. In LoTSS Data Release 1 an automated statistical identification process for compact sources was supplemented by a citizen science identification process. I present a novel method for automating the host identification of extended sources by using ridgelines, which trace the assumed direction of fluid flow through the points of highest flux density. Applying my code, RL-XID, I demonstrate that ridgelines are versatile; they can be used both for optical host identification and morphological studies. RL-XID draws ridgelines for 85% of sources brighter than 10 mJy and larger than 15 arcsec, with an improved performance of 96% for the subset >30 mJy and >60 arcsec. I demonstrate that RL-XID successfully identifies the host for 98% of the sources with successfully drawn ridgelines, and performs at a comparable level to visual identification via citizen science. Exploring galaxy populations helps us to understand their evolution and build better population models. I present new VLA observations that reveal the structure of a population of low-luminosity FRII radio galaxies discovered in LoTSS. Fanaroff and Riley (1974) identified a relationship between luminosity and radio structure, with FRIs having low-luminosity, centre bright jets and FRIIs having higher luminosity, edge-brightened jets. Using LoTSS, Mingo et al (2019) demonstrated an overlap in luminosity between FRI/FRII morphology, discovering a sub-sample of FRIIs with luminosities up to three magnitudes lower than the typical FR break. To continue to apply the traditional FR classifications in upcoming surveys we need to understand the structure and dynamics of the low-luminosity FRII population. The VLA observations I present in this thesis are a sample of LoTSS-selected low-luminosity FRIIs which allow me to make comparisons between the two FRII luminosity populations. I found systematic differences in the prevalence of compact features, with a higher fraction of cores in the low luminosity sample, and a higher fraction of hotspots in the high luminosity sources. I have also identified six new remnant candidates and three new restarting candidate sources

Overview of the 2010 Carbonaceous Aerosols and Radiative Effects Study (CARES)

Substantial uncertainties still exist in the scientific understanding of the possible interactions between urban and natural (biogenic) emissions in the production and transformation of atmospheric aerosol and the resulting impact on climate change. The US Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) program's Carbonaceous Aerosol and Radiative Effects Study (CARES) carried out in June 2010 in Central Valley, California, was a comprehensive effort designed to improve this understanding. The primary objective of the field study was to investigate the evolution of secondary organic and black carbon aerosols and their climate-related properties in the Sacramento urban plume as it was routinely transported into the forested Sierra Nevada foothills area. Urban aerosols and trace gases experienced significant physical and chemical transformations as they mixed with the reactive biogenic hydrocarbons emitted from the forest. Two heavily-instrumented ground sites – one within the Sacramento urban area and another about 40 km to the northeast in the foothills area – were set up to characterize the evolution of meteorological variables, trace gases, aerosol precursors, aerosol size, composition, and climate-related properties in freshly polluted and "aged" urban air. On selected days, the DOE G-1 aircraft was deployed to make similar measurements upwind and across the evolving Sacramento plume in the morning and again in the afternoon. The NASA B-200 aircraft, carrying remote sensing instruments, was also deployed to characterize the vertical and horizontal distribution of aerosols and aerosol optical properties within and around the plume. This overview provides: (a) the scientific background and motivation for the study, (b) the operational and logistical information pertinent to the execution of the study, (c) an overview of key observations and initial findings from the aircraft and ground-based sampling platforms, and (d) a roadmap of planned data analyses and focused modeling efforts that will facilitate the integration of new knowledge into improved representations of key aerosol processes and properties in climate models.United States. Dept. of Energy. Atmospheric System Research Program (Contract DE-AC06-76RLO 1830)United States. National Oceanic and Atmospheric AdministrationUnited States. National Aeronautics and Space Administration. HQ Science Mission Directorate Radiation Sciences ProgramUnited States. National Aeronautics and Space Administration. CALIPSO ProgramUnited States. Dept. of Energy. Atmospheric Radiation Measurement Program (Interagency Agreement No. DE-AI02-05ER63985