In this thesis, the optical communication systems for millimeter-scale sensing and communication devises known as "Smart Dust" are described and analyzed. A smart dust element is a self-contained sensing and communication system that can be combined into roughly a cubic-millimeter mote to perform integrated, massively distributed sensor networks. The suitable passive optical and fiber-optic communication systems will be selected for the further performance design and analysis based on the requirements for implementing these systems. Based on the communication link designs of the free-space passive optical and fiber-optic communication systems, the simulations for link performance will be performed. / Master of Science

Low-cost sensors have the potential to create dense air monitoring networks that help enhance our understanding of pollution exposure and variability at the individual and neighborhood-level; however, sensors can be easily influenced by environmental conditions, resulting in performance inconsistencies across monitoring settings. During summer 2020, 20 low-cost particulate sensors were deployed with a reference PM2.5 monitor in Denton, Texas in preparation for calibration. However, from mid to late-summer, dust transported by the Saharan Air Layer moved through the North Texas region periodically, influencing the typical monitoring pattern exhibited between low-cost sensors and reference instruments. Traditional modeling strategies were adapted to develop a new approach to calibrating low-cost particulate sensors. In this study, data collected by sensors was split according to a novel dust filter into dust and non-dust subsets prior to modeling. This approach was compared with building a single model from the data, as is typically done in other studies. Random forest and multiple linear regression algorithms were used to train models for both strategies. The best performing split-model strategy, the multiple linear regression models split according to dust and non-dust subsets (combined R2 = 0.65), outperformed the best performing single-model strategy, a random forest model (R2 = 0.49). The results from this study indicate that low-cost sensor performance can be greatly influenced by the presence of dust, and that adaptive strategies, like the ones presented in this paper, are necessary when calibrating sensors in environments that may experience pollution from inconsistent sources throughout the year.

Harmattan and Dust (sand) storms together with anthropogenic activities including the use of firewood and kerosene as fuel for cooking, and diesel/petrol generators for electricity generation are potential sources of particulate and gaseous pollutants in homes in Damaturu town, Nigeria. Other activities like the burning of locally produced incense and mosquito coils as well as the use of aerosol sprays are further possible sources of indoor pollution, which may result in exposure of people to a range of pollutants through inhalation, by ingestion of settled dusts as well as dermal contact. Local people associate occurrence of dust events with adverse health effects and hence there is a need for an understanding of the composition of the settled and airborne dusts in order to assess the possible associated health risks. The first phase of the study involved selection and development of methods of dust sampling and analysis. For validation of the methods employed and to establish a broad understanding of the characteristics of the settled dusts, an initial survey study was conducted involving the application of thermal desorption/gas chromatography/mass spectrometry (TD/GC/MS) analysis for organic compound analysis, scanning electron microscopy (SEM), inductively coupled plasma-mass spectrometry (ICP-MS) for analysis of metals, and microbiological analysis. Airborne samples were also collected using sorbent tubes to determine organic compounds in air during activities such as cooking with kerosene, gas, and firewood as well as during electricity generation with fossil fuels. Carbon monoxide (CO) and ultrafine particles (UFPs) monitored simultaneously during some of the household activities. The study involved a novel method of extracting organic chemical emissions from dust by heating of the dusts directly in a micro chamber (μ-CTETM) and collection of emissions on sampling tubes. The method provided a relatively quick way of collecting chemical emissions from dusts that are readily available for release. The sampled tubes were analysed by TD/GC/MS. The conventional solvent extraction of the dusts was also carried out and the extracts were analysed by liquid injection-GC/MS and results of the two methods compared. The study determined a number of constituents (metals, SVOCs, phthalates and physical properties) of dusts collected from households in Damaturu during different weather events and from different indoor/outdoor locations; and compared with some UK samples. The samples investigated include dusts deposited; during two notable dusty-weather events (Harmattan and Storm) as well as when there was no notable dust event; during human activities; and dusts from different types of buildings (modern and traditional homes) as well as inside and outside homes. A standard reference material for organic chemicals (SRM 2585) was also analysed. The physical characterization of the settled house dust samples analysed revealed the various shapes and sizes, and elemental composition of the constituents, which included respirable particles. The microbial analysis also indicated the presence of the spores of a host of fungi and bacterial species; and the possible contributions of household activities to the increased production of pollutants (UFP and CO) ascertained. The μ-CTE extraction of the house dusts by heating with TD/GC/MS analysis of the emissions as well as the solvent extraction-GC/MS revealed the presence of many organic chemical compounds with different analytical retention times and varying concentrations in the dust samples. Chemicals of interest quantified: benzene, hexanal, nonanal, diethyl phthalate (DEP), diisobutylphthalate (DIBP), dibutylphthalate (DBP), and diethylhexylphthalate (DEHP). A host of other chemicals commonly present in the analysed samples identified using the NIST library associated with the MS system software. These chemicals included naphthalene and C10-C16 aliphatic and aromatic hydrocarbons, which would need confirmation by running the pure compound samples. There was an observed higher concentration of the chemicals in the solvent extracts than the μ-CTE extracted dust. The higher concentration of the chemicals in the solvent extracts expected due to the aggressive removal of the chemicals by the organic solvent whereas in the case of thermal extraction only the readily available chemicals (loosely bound to the matrix) released by increases in temperature were removed. Generally, the concentrations of the chemicals found were higher in the indoor than in the outdoor dust samples. In the analysis of the dusts collected during weather events; higher chemical concentrations observed in the samples collected during Harmattan period than the other periods. The Harmattan dust period may pose increased exposures to dust and possible health risks. More exposure is expected to occur in the traditional homes compared with the modern homes due to the higher concentrations of the chemicals in both the indoors and the outdoors and this may be especially important to women and children who spend most of their times at home. Metal analysis involved microwave-assisted digestion of the dust samples followed by ICP-MS analysis. The total quant method of metal analysis for a general profiling indicated the presence of more than 50 elemental contaminants in house dust. The results of the quantitative analysis for six target metals: Cd, Cr, Cu, Ni, Pb, and Zn showed their presence in all indoor and the outdoor dust samples. The mean concentrations showed that the metals were in higher concentrations in the indoor dusts than in the outdoor dusts. The quantitative analysis carried out indicated higher metal contents in the storm dusts than the dusts during the other periods. Results of the dusts collected from modern and traditional homes indicated the presence of the metals in higher concentrations in the dusts from traditional homes than the dusts from the modern homes. The estimated mean concentrations of the metals and phthalates inadvertently ingested as a constituent of dust indicated that some of the pollutants could exceed the tolerable daily intake (TDI) due to high exposures to dust expected to be the case in Damaturu. The results of the investigation of the dust composition, combined with information on exposure to dust and pollutants, show that dusts are a risk to the health of people in the Damataru community. Recommendations are made for more studies to provide a better understanding of dust ingestion and exposure to some phthalates and heavy metals in particular and the possible health risks. To the best of my knowledge, this is the first ever research study of airborne and settled dusts undertaken in North-Eastern Nigeria.

Dust storms are one of the natural hazards, which have increased in frequency in the recent years over Sahara desert, Australia, the Arabian Desert, Turkmenistan and northern China, which have worsened during the last decade. Dust storms increase air pollution, impact on urban areas and farms as well as affecting ground and air traffic. They cause damage to human health, reduce the temperature, cause damage to communication facilities, reduce visibility which delays both road and air traffic and impact on both urban and rural areas. Thus, it is important to know the causation, movement and radiation effects of dust storms. The monitoring and forecasting of dust storms is increasing in order to help governments reduce the negative impact of these storms. Satellite remote sensing is the most common method but its use over sandy ground is still limited as the two share similar characteristics. However, satellite remote sensing using true-colour images or estimates of aerosol optical thickness (AOT) and algorithms such as the deep blue algorithm have limitations for identifying dust storms. Many researchers have studied the detection of dust storms during daytime in a number of different regions of the world including China, Australia, America, and North Africa using a variety of satellite data but fewer studies have focused on detecting dust storms at night. The key elements of this present study are to use data from the Moderate Resolution Imaging Spectroradiometers on the Terra and Aqua satellites to develop more effective automated method for detecting dust storms during both day and night and generate a MODIS dust storm database.

Influence of dust particles on the characteristics of premixed methane-air flames has been studied in this dissertation. Experiments are performed in a Bunsen burner type experimental set-up called Hybrid Flame Analyzer (HFA), which can be used to measure the burning velocity of gas, dust, and hybrid (gas and dust) premixed flames at constant pressure operating conditions. In the current study, analysis of particle-gas-air system of different types of dust particles (at particle size, dp = 75-90 µm) in premixed methane-air (ϕg = 0.8, 1.0 and 1.2) flames. Coal, sand, and sodium bicarbonate particles are fed along with a premixed methane-air mixture at different concentrations (λp = 0-75 g/m3) in both laminar and turbulent conditions. First, the variation of laminar burning velocity with respect to the concentration of dust particles, and type of dusts are investigated for different equivalence ratios. Second, the laminar premixed flame extinction with inert and chemical suppressant particles are studied. Third, the variation of turbulent burning velocity of these hybrid mixtures are investigated against different turbulent intensities apart from the different concentrations and types of dusts. Fourth, the radiative fraction of heat released from turbulent gas-dust premixed flames are also presented against the operating parameters considered. Combustible dust deflagration hazard is normally quantified using the deflagration index (Kst) measured using a constant volume explosion sphere, which typically is a sealed 20-liter metal sphere where a premixed mixture is ignited at the center and the progression of the resulting deflagration wave is recorded using the pressure measured at the vessel wall. It has been verified from prior studies that the quantification of the turbulence by this method is questionable and there is a need to analyze the controlling parameters of particle-gas-air premixed system accurately through a near constant pressure operated experimental platform. Thus, the main objective of this study is to analyze the influence of dust particles on premixed methane-air flames at near constant pressure conditions. The turbulent burning velocity is calculated by averaging the measured flame heights and the laminar burning velocity is calculated through the premixed cone angle measurements from several high-speed shadowgraph images obtained from the experiments. The turbulent intensity and length scale of turbulence generated by a perforated plate in the burner is quantified from the hot-wire anemometer measurements. Radiative heat flux is also measured for each of the turbulent test conditions. The outcomes from these experiments are: 1. An understanding of the variation of turbulent burning velocity of gas-dust premixed flames as a function of dust type, turbulent intensity, integral length scale, dust concentration and gas phase mixture ratio. 2. An understanding of the flame extinction characteristics and variation of laminar burning velocity of gas-dust premixed flames as a function of dust concentration and gas phase mixture ratio. 3. Quantify the radiative heat flux and radiative fraction of heat released from gas-dust turbulent premixed flames as a function of dust type, turbulent intensity, dust concentration and gas phase mixture ratio. Dust type and concentration play an important role in deciding the trend in the variation of both laminar (SL) and turbulent burning velocity (ST). Coal particles, with the release of volatile (methane), tend to increase burning velocities except for fuel rich conditions and at higher coal concentrations at larger turbulent intensities. At a higher turbulent intensity and larger concentrations, higher ST values are observed with the addition of sand. Sodium bicarbonate addition, with the release of CO2 and H2O, decreased the burning velocity at all the concentrations, turbulent intensities and equivalence ratios. Laminar flame extinction was observed with the addition of sand and sodium bicarbonate particles at conditions exceeding certain critical dust concentrations. These critical concentrations varied with the equivalence ratios of gaseous premixed flames. The turbulence modulation exhibited by particles and particle concentration is evident in these observations. The independent characteristic time scale analysis performed using the experimental data provided further insights to the results. The chemical and convective times in gas phase confirm the broadened preheat thin reaction zone regime in the current test cases, which has an effect of attenuating turbulence and thereby the resulting turbulent burning velocity. The particle time scale analysis (Stokes number) show that the effect of particles and particle concentration is to slightly enhance the turbulence and increase the turbulent burning velocity at lower concentrations. However, the time scale analysis of particle vaporization (vaporization Damköhler number) indicate an increase in the vaporization rate for particles (coal and sodium bicarbonate) resulting in a decrease in their turbulent burning velocities at higher concentrations and turbulent intensities. Sodium bicarbonate has higher evaporation rate than coal at same level of turbulence and the absence of this effect for inert (sand) results in higher turbulent burning velocities at higher concentrations. An increase in the turbulent intensity increases the vaporization rate of particles. The investigation on radiative fraction of heat released by methane-air-dust turbulent premixed flames identified that, the addition of dust particles increases the radiative fraction irrespective of the dust type due to the radial and axial extension of flame. A unified approach to couple this multiple complex phenomenon of turbulence, particle interaction, particle vaporization and combustion in particle laden premixed gaseous flames is the direction for future research.

Thesis (M.S.)--Rochester Institute of Technology, 2007. / Typescript. Includes bibliographical references (leaves 106-109).

This study is focused on the identification of the sources and processes affecting levels and composition of PM10 and PM2.5 from air quality monitoring networks in Eastern Spain. This is a multidisciplinary study. Time series of TSP and PM10 recorded from 1996 to 2000 are interpreted to assess the role of local, regional and distant sources in PM levels in this region. To this is end, the influence of the meteorology on PM levels recorded at nineteen rural, urban and industrial monitoring stations is studied by means of synoptic charts, back-trajectories and local meteorological variables. The impact of African dust transport on PM levels is investigated by means of simulations in the SKIRON forecast system and by TOMS satellite observations. Moreover, a chemical characterisation of PM10, PM2.5 and TSP size segregated fractions and a daily PM10 and PM2.5 source apportionment by two receptor modelling techniques are performed. For this purpose, 24-hour samples of PM10 were collected for 16, 12 and 5 months at rural, urban and industrial sites, respectively. PM2.5 was sampled at the urban site simultaneously with PM10. The results showed that day-to-day variations in PM levels are highly influenced by the meteorology. From March to October, PM levels at rural, urban and industrial sites vary as a function of the concatenation of Atlantic air mass advections (Atlantic episodes with low PM levels) and regional circulations (Regional events with high PM and O3 levels) which induce the PM transport from urban/industrial to rural sites and the ageing of polluted air masses in the Western Mediterranean. From November to February low PM levels are recorded at rural sites, and variations in PM levels at urban/industrial sites are governed by the successive occurrence of Atlantic episodes and Local urban/industrial pollution events (with high PM, NOx and CO levels). The African dust events mainly occur from January to October and induce very high PM levels in all sites. As a result of the frequency and intensity of the Regional episodes, PM levels at rural sites undergo a seasonal evolution with a summer maximum. The difference between PM levels at urban and rural sites presents an autumn-winter maximum owing to the occurrence of intensive Local urban pollution events. The meteorological context in which the aforementioned episodes occur is discussed, with special emphasis on the synoptic scenarios giving rise to the African dust outbreaks in the different seasons. Levels of PM components at the different study sites were compared. The seasonal evolution and the grain size distribution of these components was studied and the form of occurrence was determined. The chemical characterisation shows that high levels of natural mineral dust components (e.g. Al, Fe, Mg, Ti, Sr, Ca) are simultaneously recorded in PM10 and PM2.5 at all sites during African episodes. Other interesting findings are: 1) a marked seasonal evolution of nitrate levels and grain size distribution due to the occurrence of ammonium-nitrate in autumn-winter, 2) an excess of Na with respect to the Na/Cl marine ratio in summer owing to reactions of acids with sea salt, and 3) high background levels of ammonium-sulphate in summer. Moreover, the levels of elemental, organic and mineral carbon were determined. At the rural site, the PM10 annual mean reaches 22µg/m3, the main contributions being secondary particles from industrial emissions (27% of PM10), vehicle exhausts (14-23%), natural mineral dust (23%) and sea spray (5-9%). At the urban kerbside station, the PM10 annual mean reaches 49µg/m3, the main contributions being vehicle exhausts (35-45% of PM10), secondary particles from industrial emissions (24-31%), natural + road dust (25%) and sea spray (4-6%). At the urban kerbside station, the PM2.5 annual mean reaches 34µg/m3, the main contributions being vehicle exhausts (41-53% of PM2.5), secondary particles from industrial emissions (29-35%) and mineral dust (9-11%). These results have important implications for the implementation of the PM10 EU standards. The natural load in ambient PM10 levels in Eastern Spain accounts for 30-40% of the 2010 EU annual PM10 limit value (20µg/m3). In this region it will not be easy to meet this limit value given that the annual PM10 levels are in the range 17-20µg/m3 at rural, 30-45µg/m3 at urban and 45-60µg/m3 at industrial sites. The high background levels of PM10 in this region are favoured by the specific orographic and meteorological context of the Mediterranean and by the high load of mineral dust caused by the soil re-suspension and the frequent occurrence of African dust events. At rural sites, 2-5 exceedances of the EU daily PM10 limit value (50µg/m3) are recorded every year during African dust outbreaks. On average, 15 African induced and 40-80 non-African induced exceedances of the EU daily PM10 limit value are recorded every year at the urban kerbside stations. The parameter selected for PM monitoring is a key factor. Most of the PM species resulting from combustion and vehicle exhaust emissions have a fine size distribution (<2.5µm), with exception of nitrate in summer, whereas sea spray and mineral dust present a coarse size distribution. The interference of African dust in the PM monitoring is significantly reduced when PM2.5 instead of PM10 is monitored. Natural mineral dust concentrations during African episodes are in the ranges 20-30µg/m3 in PM10 and 10-15µg/m3 in PM2.5. However, PM2.5 is not a suitable parameter for PM monitoring in all environments. The selection of PM10 or PM2.5 should be conditioned by the type of anthropogenic activity. At urban sites, PM2.5 contains mainly vehicle exhaust products, whereas the road traffic dust principally occurs in the 2.5-10µm fraction. PM2.5 is not a suitable parameter for monitoring some industrial activities (e.g. ceramics, cement production or mining) with primary PM emissions in the 2.5-10µm range.

In this thesis, I enquire into how the USA – our world’s wealthiest and most powerful nation –  and its federal government has dealt with two of its most severe natural disasters: the drought and dust storms that plagued the Great Plains during the 1930’s, i.e. the Dust Bowl, and Hurricane Katrina, which made landfall in late August 2005.  I attempt to identify differences and similarities and analyze if and, in that case, how the hegemonic politico-economic paradigm affected the federal management of these crises. This comparison is made relevant by the fact that two differing paradigms were at play during these events. In the thirties, President Franklin D. Roosevelt launched his “New Deal”, a series of counter cyclical measures in line with the Keynesian school of economics, as a response to the overwhelming economic depression as well as the raging drought. In sharp contrast, Hurricane Katrina swept over a country ridden by decades of neoliberal governance. I show that political economy plays an important role in the success and/or failure of, in this case, the United States’ management of natural disasters. Finally, I argue for the return (or, rather, the creation) of an expanded and more socially and environmentally conscious public sector, which, in times of crisis, is able to represent all of its citizens – regardless of class or race.

No description available.

Master's thesis "effect of dust particles on sliding electrical contact" summarizes the sliding contact theory and praxe in rotating electrical machines. The principle of brush machines is described and the working environments are defined. The individual components of the sliding contact and reasons of their degradation are described in detail. Emphasis is placed on the influence of foreign particles, which can be assessed in practice by the method of dust particles. Furthermore, these theoretical knowledge was used in the practical assessment of the technical condition of various machines, as well as the called method. One set of brushes for the traction motor of the locomotive T47.0 was also experimentally innovated.