Chronic respiratory diseases such as asthma and chronic bronchitis have significantly increased in prevalence in Africa over the past 10 years. Recent studies have demonstrated that exposure to air pollution may be associated with an increased risk of chronic respiratory diseases. However, such studies have predominantly been conducted in western societies or often used urbanicity as a proxy for exposure to air pollution. Therefore, we evaluated the association between PM2.5 exposure and asthma/chronic bronchitis in Senegal. A cross-sectional study was conducted for the time period of 3 October 2010 to 28 April 2011 using annual concentrations of PM2.5 measured via multiple satellite instruments, and asthma/chronic bronchitis, which was self-reported at baseline via a health survey questionnaire. We used mixed model logistic regression to evaluate the relationship between PM2.5 exposure and asthma/chronic bronchitis risk while adjusting for lifestyle factors, location, and other air pollutants. Sex was evaluated as an effect modifier. The adjusted association between PM2.5 and asthma/chronic bronchitis was 1.03 (95%CI: 0.99 – 1.06). In males the adjusted odds ratio was 1.09 (95%CI: 1.03-1.15), compared to females (aOR 1.01 (95%CI: 0.97 – 1.05). Our results suggest that increasing levels of exposure to PM2.5 puts individuals at a higher risk for chronic respiratory diseases, especially men. These findings have significant policy implications and should be built upon in future research.

<p> Pollution problems have drawn worldwide awareness and become significantly important now. Particulate matter (PM) emission is one of the key pollution issues. Particulate matter has a significant impact on the environment and human health, especially particle sizes that range below lOJJ.m. Researches continuously work an improvement of fine particulate matter collections emitted from all kinds of sources, such as automobiles, industrial combustion, etc. Governments in many countries are planning to regulate the PM emission from the existing PM10 (particle diameter<10μm) to new limits PM2.5 (particle diameter<2.5μm) within the next few years. For this reason, present PM control system needs to be improved. </p> <p> The objective of this work is to develop a dust flow separator type electrostatic precipitator (DFS-ESP) for the effective control of fine particulate matter emission from natural gas combustions. The characteristic of PM emitted from natural gas combustion is studied, and the performance of a DFS-ESP is evaluated by experiments and numerical predictions. </p> <p> An experiment was conducted for natural gas combustion exhaust flow rates from 2.5 to 9 Nm^3/h, ESP applied voltages from 0 to 30kV, and gas temperature from 80 to 160°C. A series of particle measurements were conducted at upstream, downstream and middle of the DFS-ESP system by an optical particle counter for particle mass density, and by condensation nucleate particle counter for particle size distributions and particle number density. Particle sampled from the natural gas combustion system was also analyzed by an environmental scanning electron microscope (ESEM) technique. Flow velocity profile and pressure drop of the DFS-ESP were measured by a Pitot tube and diaphragm type pressure transducer, respectively. </p> <p> The experimental results show that the particle size emitted from natural gas combustion ranges from 17 to 300nm in diameter, and the volume density is approximately from 5 x 10^8 #pt/m^3 to 5 x 109 #pt/m^3 depending on the combustion conditions. The dust flow separator can concentrate 90% of fine particles in 1 to 3% of the gas flow and divert it from the main flow to the ESP section where the particles can be removed. In terms of overall particle collection efficiency, the DFS-ESP system can remove up to 90% of the particles based on the number density. The pressure drop across the DFS-ESP is observed to be lower than lPa for the present range of flow rate, which is within acceptable limits for industrial applications. </p> / Thesis / Master of Applied Science (MASc)

<p> Increasingly stringent legislation governing the emissions of diesel engine particulate matter (DPM) has required the development of technological improvements to diesel engines, fuels and exhaust treatments. A main focus of diesel particulate matter abatement is on exhaust after treatment, that consists of the removal of particulate matter from the exhaust gas after it exits the engine. This is currently accomplished with regenerative diesel particulate traps that are effective at removing DPM, but are costly and introduce a significant pressure drop in the exhaust flow.</p> <p> The objective of this study was to evaluate the potential of a novel particulate removal system consisting of a particulate flow separator combined with electrostatic precipitators (ESPs). Previous application of this system to natural gas emissions resulted in collection efficiencies larger than 90% with negligible pressure drop.</p> <p> The ESPs used in the proposed flow separator-ESP were characterized and have collection efficiencies of up to 99% at the flow rates studied. The flow separator-ESP was characterized with a straight inlet section and an expanding inlet section. The collection efficiency of the flow separator-ESP configured with the expanding inlet section was up to 60% for a flow rate of 2.5 kg/hr, that corresponded to laminar flow with Reynolds number of 1100. Collection efficiencies on the order of 20% were obtained for exhaust flow rates of 3.75 kg/hr (Re = 1500) and 5.0 kg/hr (Re = 2100) for both inlet configurations, and 2.5 kg/hr with the straight inlet. The effectiveness of the current design is limited by exhaust flow rate.</p> <p> The diesel exhaust gas was sampled using a partial flow dilution tunnel developed specifically for this study. The dilution ratio for this system can be estimated to within ±10% using volumetric flow measurements. It was found that changes in the dilution and sampling velocity ratios for diesel exhaust have some effect on measured particulate matter mass concentrations.</p> / Thesis / Master of Applied Science (MASc)

Yes / The increase availability of operational data from the fleets of cars in the field offers opportunities to deploy machine learning to identify patterns of driver behaviour. This provides contextual intelligence insight that can be used to design strategies for online optimisation of the vehicle performance, including compliance with stringent legislation. This paper illustrates this approach with a case study for a Diesel Particulate Filter, where machine learning deployed to real world automotive data is used in conjunction with a reliability inspired performance modelling paradigm to design a strategy to enhance operational performance based on predictive driver behaviour. The model-in-the-loop simulation of the proposed strategy on a fleet of vehicles showed significant improvement compared to the base strategy, demonstrating the value of the approach.

Investigation of momentum and heat transfer between the fluid and solid phase is critical to the study of fluid-particle systems. Dense suspensions are characterized by the solid fraction (ratio of solid volume to total volume), the particle Reynolds number, and the shape of the particle. The behavior of non-spherical particles deviates considerably from spherical particle shapes which have been studied extensively in the literature. Momentum transfer, to first-order, is driven by drag forces experienced by the particles in suspension, followed by lift and lateral forces, and also through the transmission of fluid torque to the particles. The subject of this thesis is a family of prolate ellipsoidal particle geometries of aspect ratios (AR) 2.5, 5.0 and 10.0 at nominal solid fractions (φ) between 0.1 and 0.3, and suspensions of cylinders of AR=0.25. The nominal particle Reynolds number (Re) is varied between 10 to 200, representative of fluidized beds. Fluid forces and heat transfer coefficients are obtained numerically by Particle Resolved Simulations (PRS) using the Immersed Boundary Method (IBM). The method enables the calculation of the interstitial flow and pressure field surrounding each particle in suspension leading to the direct integration of fluid forces acting on each particle in the suspension. A substantial outcome of the research is the development of a new drag force correlation for random suspensions of prolate ellipsoids over the full range of geometries and conditioned studied. In many practical applications, especially as the deviation from the spherical shape increases, particles are not oriented randomly to the flow direction, resulting in suspensions which have a mean preferential orientation. It is shown that the mean suspension drag varies linearly with the orientation parameter, which varies from -2.0 for particles oriented parallel to the flow direction to 1.0 for particles normal to the flow direction. This result is significant as it allows easy calculation of drag force for suspension with any preferential orientation. The heat transfer coefficient or Nusselt number is investigated for prolate ellipsoid suspensions. Significantly, two methods of calculating the heat transfer coefficient in the literature are reconciled and it is established that one asymptotes to the other. It is also established that unlike the drag force, at low Reynolds number the suspension mean heat transfer coefficient is very sensitive to the spatial distribution of particles or local-to-particle solid fractions. For the same mean solid fraction, suspensions dominated by particle clusters or high local solid fractions can exhibit Nusselt numbers which are lower than the minimum Nusselt number imposed by pure conduction on a single particle in isolation. This results from the dominant effect of thermal wakes at low Reynolds numbers. As the Reynolds number increases, the effect of particle clusters on heat transfer becomes less consequential. For the 0.25 aspect ratio cylinder, it was found that while existing correlations under predicted the drag forces, a sinusoidal function F_(d,θ)=F_(d,θ=0°)+(F_(d,θ=90°)-F_(d,θ=0°) )sin⁡(θ) captured the variation of normalized drag with respect to inclination angle over the range 10≤Re≤300 and 0≤φ≤0.3. Further the mean ensemble drag followed F_d=F_(d,θ=0°)+1/2(F_(d,θ=90°)-F_(d,θ=0°)). It was shown that lift forces were between 20% to 80% of drag forces and could not be neglected in models of fluid-particle interaction forces. Comparing the pitching fluid torque to collision torque during an elastic collision showed that as the particle equivalent diameter, density, and collision velocities decreased, fluid torque could be of the same order of magnitude as collisional torque and it too could not be neglected from models of particle transport in suspensions. / Doctor of Philosophy / Momentum and heat exchange between the fluids (air, water…) and suspensions of solid particles plays a critical role in power generation, chemical processing plants, pharmaceuticals, in the environment, and many other applications. One of the key components in momentum exchange are the forces felt by the particles in the suspension due to the flow of the fluid around them and the amount of heat the fluid can transfer to or from the particles. The fluid forces and heat transfer depend on many factors, chief among them being the properties of the fluid (density, viscosity, thermal properties) and the properties of the particles in the suspension (size, shape, density, thermal properties, concentration). This introduces a wide range of parameters that have the potential to affect the way the fluid and particles behave and move. Experimental measurements are very difficult and expensive to conduct in these systems and computational modeling can play a key role in characterization. For accuracy, computational models have to have the correct physical laws encoded in the software. The objective of this thesis is to use very high-fidelity computer models to characterize the forces and heat transfer under different conditions to develop general formulas or correlations which can then be used in less expensive computer models. Three basic particle shapes are considered in this study, a sphere, a disk like cylindrical particles, and particles of ellipsoidal shapes. More specifically, Particle Resolved Simulations of flow through suspensions of ellipsoids with aspect ratio of 2.5, 5, 10 and cylinders with aspect ratio of 0.25 are performed. The Reynolds number range covered is [10, 200] for ellipsoids and [10, 300] for cylinders with solid fraction range of [0.1, 0.3]. New fluid drag force correlations are proposed for the ellipsoid and cylinder suspensions, respectively, and heat transfer behavior is also investigated.

Air quality management strategies in the US are developed largely from estimates of emissions, some highly uncertain, rather than actual measurements. Improved knowledge based on measurements of real-world emissions is needed to increase the effectiveness of these strategies. Consequently, the objectives of this research were to (1) quantify relationships among urban emissions sources, land use, and demographics, (2) determine the spatial and temporal variability of emissions, and (3) evaluate the accuracy of official emissions estimates. These objectives guided three field campaigns that employed a unique mobile laboratory equipped to measure pollutant fluxes by eddy covariance. The first campaign, conducted in Norfolk, Virginia, represented the first time fluxes of nitrogen oxides (NO_x) were measured by eddy covariance in an urban environment. Fluxes agreed to within 10% of estimates in the National Emissions Inventory (NEI), but were three times higher than those of an inventory used for air quality modeling and planning. Additionally, measured fluxes were correlated with road density and increased development. The second campaign took place in the Tijuana-San Diego border region. Distinct spatial differences in fluxes of carbon dioxide (CO₂), NO_x, and particles were revealed across four sampling locations with the lowest fluxes occurring in a residential neighborhood and the highest ones at a port of entry characterized by heavy motor vehicle traffic. Additionally, observed emissions of NO_x and carbon monoxide were significantly higher than those in emissions inventories, suggesting the need for further refinement of the inventories. The third campaign focused on emissions at a regional airport in Roanoke, Virginia. NOx and particle number emissions indices (EIs) were calculated for aircraft, in terms of grams of pollutant emitted per kilogram of fuel burned. Observed NO_x EIs were ~20% lower than those in an international databank. NO_x EIs from takeoffs were significantly higher than those from taxiing, but relative differences for particle EIs were mixed. Observed NO_x fluxes at the airport agreed to within 25% of estimates derived from the NEI. The results of this research will provide greater knowledge of urban impacts to air quality and will improve associated management strategies through increased accuracy of official emissions estimates. / Ph. D.

The term diesel particulate matter (DPM) is used to refer to the solid phase of diesel exhaust, which is mainly composed of elemental carbon and organic carbon. DPM is generally in the nano-size range (i.e., 10-1,000 nm). Occupational exposure is a health concern, with effects ranging from minor eye and respiratory system irritation to major cardiovascular and pulmonary diseases. Significant progress has been made in reducing DPM emissions by improving fuels, engines and after-treatment technologies. However, the mining industry, in particular, remains challenged to curb exposures in some operations where relatively many diesel engines are working in confined environments with relatively low airflow. Basic theory and a limited amount of prior research reported in the literature suggest that water sprays may be able to scavenge airborne DPM. The goals of the work presented in this thesis were to build an appropriate laboratory set up and to test the efficacy of micron-scale water (or fog) droplets to remove DPM from an air stream. The general experimental approach was to direct diesel exhaust through a chamber where fog drops are generated, and to measure DPM up- and down-stream of the treatment. Initially, fundamental experiments were conducted to explore the effect of the fog drops on the removal of (electrically neutralized) DPM from a dry exhaust stream. Compared to no treatment (i.e., control) and with the use of a diffusion dryer downstream of the fog treatment, the fog improved DPM removal by about 57% by mass and 45% by number density (versus no treatment). Without the use of the diffusion dryer, improvement in DPM removal was about 19% by mass. Analysis of the results suggests that a likely mechanism for the DPM removal in this experimental system is thermal coagulation between DPM and fog droplets, followed by gravitational settling and/or impaction of the droplets with system components. Further tests using raw exhaust (i.e., neither dried nor neutralized) having a higher DPM number density; shorter residence times; additional fogging devices; and no diffusion dryer downstream of the fog treatment were also carried out. These yielded an average overall improvement in DPM mass removal of about 45% attributed to the fog treatment (versus no treatment). The significant increase in DPM removal in these tests compared to the initial test (i.e., 19% removal by mass) cannot be fully explained by differences in residence time or DPM and fog droplet densities. Increased humidity in the system (due to the undried exhaust) may have allowed for a larger mean droplet size, and therefore might explain more rapid settling of DPM-laden droplets. Another possible contributing factor is ambient surface charge of the DPM, which might perhaps result in more efficient attachment between DPM and fog drops and/or increased deposition loses in the system. / Master of Science

Land application of biosolids has been demonstrated to improve nutrient availability (mainly N and P) and improve organic matter in soils, but the effects of biosolids on C sequestration and N cycling in the Mid-Atlantic region is not well understood. The objectives were: 1) to investigate soil C sequestration at sites with a long-term history of biosolids either in repeated application or single large application; 2) to characterize and compare soil C chemistry using advanced 13C nuclear magnetic resonance (NMR) and C (1s) near edge x-ray absorption fine structure (NEXAFS) spectroscopic techniques; and 3) to compare biosolids types and tillage practices on short-term N availability in the Coastal Plain soils. Biosolids led to C accumulation in the soil surface (< 15 cm) after long-time application in both Piedmont and Coastal Plain soils. The C saturation phenomenon occurred in Coastal Plain soils, thus additional soil C accumulation was not achieved by increasing C inputs from biosolids to the Coastal Plain. Soil organic C from profiles in the field sites was not different at depths below the plow layer (15-60 cm). The quantitative NMR analyses concluded that O-alkyl C was the dominant form in the particulate organic matter (POM), followed by aromatic C, alkyl C, COO/N-C=O, aromatic C-O, OCH3 / NCH and ketones and aldehydes. The aliphatic C and aromatic C were enriched but the O-alkyl C was decreased in the biosolids-amended soils. The changes indicated that the biosolids-derived soil C was more decomposed and, thus, more stable than the control. The NEXAFS spectra showed that O-alkyl C was the dominant form in the POM extracted from biosolids-amended soils, followed by aromatic C, alkyl C, carboxylic C and phenolic C groups. These results were similar to those from NMR analysis. The regression and correlation analyses of C functional groups in the POM between NEXAFS and NMR indicated that both techniques had good sensitivity for the characterization of C from biosolids-amended soils. To evaluate short-term biosolids N availability, a three-year field study to investigate the effects of lime-stabilized (LS) and anaerobically digested (AD) biosolids on N availability in a corn-soybean rotation under conventional tillage and no-tillage practices was set up in 2009-2011. Results showed that both LS and AD biosolids increased spring soil nitrate N, plant tissue N at silking, post-season corn stalk nitrate N, grain yield, and soil total N by the end of the growing season. The same factors used to calculate plant available N for incorporated biosolids can be used on biosolids applied to no-till systems in coarse-textured soils. All these results indicated that the application of biosolids affects the long-term quantification and qualification of soil organic C and also improve short-term N availability in the Mid-Atlantic region. / Ph. D.

Diesel particulate matter (DPM) is comprised of two main fractions, organic carbon (OC) and elemental carbon (EC). DPM is the solid portion of diesel exhaust and particles are submicron in size typically ranging from 10 to 1000 nanometers. DPM is a known respirable hazard and occupational exposure can lead to negative health effects. These effects can range from irritation of the eyes, nose, and throat to more serious respirable and cardiovascular diseases. Due to the use of diesel powered equipment in confined airways, underground mine environments present an increased risk and underground mine works can be chronically overexposed. Current engineering controls used to mitigate DPM exposure include cleaner fuels, regular engine maintenance, ventilation controls, and enclosed cabs on vehicles. However even with these controls in place, workers can still be overexposed. The author's research group has previously tested the efficacy of a novel, fog-based scrubber treatment for removing DPM from the air, in a laboratory setting. It was found that the fog treatment improved DPM removal by approximately 45% by number density compared to the control trial (fog off). The previous work stated thermal coagulation between the fog drops and the DPM, followed by gravitational settling of the drops to be the likely mechanisms responsible for the DPM removal. The current work investigated the efficacy of the fog treatment on a larger scale in an underground mine environment, by using a fogging scrubber to treat the entire exhaust stream from a diesel vehicle. A total of 11 field tests were conducted. Based on measurements of nanoparticle number concentration at the inlet and outlet of the scrubber, the fog treatment in the current work showed an average improvement in total DPM removal of approximately 55% compared to the control (fog off) condition. It was found that the treatment more effectively removed smaller DPM sizes, removing an average of 84 to 89% of the DPM in the 11.5, 15.4, and 20.5 nanometer size bins and removing 24 to 30% of the DPM in the 88.6, 115.5, and 154 nanometer size bins. These observations are consistent with expectations since the rate of coagulation between the DPM and fog drops should be greater for smaller diameters. Further analysis of the DPM removal was aided by the development of a mechanistic model of the fogging scrubber. The model uses the inlet data from the experimental tests as input parameters, and it outputs the outlet concentration of DPM for comparison to the experimental outlet data. Results provided support for the notion that DPM removal relies on DPM-fog drop coagulation, and subsequent removal of the DPM-laden drops as opposed to DPM removal by diffusion or inertial impaction of DPM directly to the walls. The model results suggest that inertial impaction of these drops to the scrubber walls is likely much more important than gravitational settling. Moreover, the ribbed geometry of the tubing used for the scrubber apparatus tested here appears to greatly enhance inertial impaction (via enhancement of depositional velocity) versus smooth-walled tubing. This is consistent with previous research that shows particle deposition in tubes with internally ribbed or wavy structures is enhanced compared to deposition in tubes with smooth walls. / Master of Science / Diesel particulate matter (DPM) describes the solid portion of diesel exhaust. These particles are in the nanometer size range (10-1000nm) and can penetrate deep within the lungs presenting a serious health hazard. Because of the use of diesel powered equipment in confined spaces, DPM presents an occupational hazard for underground mine workers. Even with the use of cleaner fuels, regular engine maintenance, proper ventilation, and enclosed vehicle cabs, workers can still be over exposed. Previous work has shown that a water fog treatment can help to remove DPM from the air in a laboratory setting. This removal is due to the DPM particles attaching to the drops, followed by the drops settling out of the air due to gravity or impacting the walls of a tube. To explore a full scale exhaust treatment, a fogging scrubber was built using a fogger and a long tube, and was tested in an underground mine on vehicle exhaust. Experimental results showed that the fog treatment was effective at removing DPM from the exhaust. On average, the fog improved DPM removal by about 55% compared to when the treatment was not employed (fog off). To better understand the mechanisms responsible for DPM removal in the scrubber, a computer model was generated. The model uses the inlet parameters from the field tests, such as inlet DPM and fog concentration and tube geometry, and predicts the scrubber outlet DPM concentration. The model results suggest that the primary way that DPM is removed from the system is by combining with fog drops, which then hit the scrubber tube walls. This effect is probably enhanced by the ribbed structure of the scrubber tubing used here, which may be important for practical applications.

Exposure to diesel engine exhaust is linked to chronic and acute illness. In underground mines, workers can be exposed to high concentrations for extended periods of time. Therefore, Mine Safety and Health Administration (MSHA) enforces personal exposure and engine emission limits. These regulations target just the solid portion of diesel exhaust, known as diesel particulate matter (DPM). The majority of DPM mass is attributed to particulate organic carbon (POC) and elemental carbon (EC). Total carbon (TC) is the sum of POC and EC and currently used as the surrogate to represent DPM as a whole. The NIOSH Method 5040 is the standard sample collection and analysis procedure. It outlines collection of submicron particulate matter samples on a quartz filter then measurement of POC and EC using a thermal-optical analysis. Error in DPM measurement occurs when volatile organic carbon (VOC) sorbs onto the particulate matter deposit and filter resulting in a positive sampling artifact. To correct for this, a dynamic blank method with two quartz filters (i.e., primary and secondary) in tandem is used. However, the accuracy of the dynamic blank correction method is dependent on equal sorption of VOC onto each filter. Observed instances of higher VOC on the secondary filter result in underestimated POC measurements and in some cases negative POC. The work presented in this thesis investigates the sources of VOC interference in particulate matter sampling and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were analyzed to look into instances of higher VOC sorption onto the secondary filter. Negative total POC results were limited to blank samples, but negative results for the POC of individual isotherms were observed in blank and DPM samples. A follow-up study looked into the possibility of sampling materials as a source of VOC that preferentially sorbs onto the secondary filter. Blank samples were assembled to test five sampling materials (i.e., two types of sample cassette, cellulose support pads, impactor cassettes, and impactors). In addition, sample storage conditions (i.e., temperature and duration) were tested for their impact on VOC sorption. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. Preferential sorption onto the secondary filter was observed in most conditions as well. A field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. The effectiveness of a temperature separation may depend on sample location. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition as well as different temperatures is suggested. It seems unlikely that a correction method using a separation temperature would be more effective than the standard dynamic blank in occupational DPM monitoring. The work presented in this thesis highlights the difficulty in accurately measuring POC. / Master of Science / Diesel Particulate matter (DPM) is the solid portion of diesel exhaust and can cause chronic and acute illness. Underground miners can regularly be exposed to high concentrations of DPM over long periods of time, therefore DPM must be monitored. Total Carbon (TC) is the sum of particulate organic and elemental carbon (POC and EC) and is used as the surrogate measurement to represent DPM. The standard method of DPM sample analysis is subject to volatile organic carbon (VOC) interference, therefore a dynamic blank correction is used. However, in some cases, the dynamic blank over- or under-corrects. This thesis presents studies to better understand the source(s) of VOC interference and possible solutions. Three existing datasets containing information from blank samples and laboratory and field DPM samples were investigated for instances of VOC interference resulting in an overcorrection. Such instances were limited to blank and low mass samples. A field study looked into the possibility of sampling materials as a source of VOC that may cause overcorrection when using the dynamic blank method. Blank samples were assembled to test five sampling materials as well as various sample storage conditions. It was discovered that all of the sample materials tested contributed VOC and, as expected, higher storage temperatures and longer storage durations increase the amount of VOC. A second field study explored thermal separation of VOC and POC as a possible alternative to the dynamic blank correction method. Two sets of DPM samples were collected from two locations in an underground stone mine and one set of ambient particulate matter samples was collected from a highly trafficked truck stop. The temperature of 175°C was used for this preliminary investigation. Results indicate that the effectiveness of temperature separation may depend on sample concentration and composition. To better understand VOC and POC evolution characteristic, further testing with a wide range of sample mass and composition, as well as, different temperatures is suggested. The work presented in this thesis highlights the difficulty in accurately measuring POC.