Master of Science / Department of Architectural Engineering / Kimberly Waggle Kramer / The American Society of Civil Engineers (ASCE) has developed standards for the design of snow loads that occur on buildings and structures. These standards are published in the Minimum Design Loads for Buildings and Other Structures, or ASCE 7, and are based on the findings of case studies and other scientific tests. However, design guidance on the possible reduction of leeward snow drifts at the junction of a roof parapet and a moderately sized roof step is limited and not specifically addressed in the ASCE 7. Therefore, a literature review and parametric study were performed to evaluate possible leeward snow drift reduction that could occur at the junction of parapets and roof steps. Leeward drift reduction was estimated using the Fetch Modification Method, the Direct Reduction Method, and the Simplistic Reduction Method for parapets with heights of 30 in. and 48 in. with upwind snow fetch distances from 100 to 300 ft and ground snow loads from 20 to 50 psf. More drift reduction was seen with the 48 in. parapets than with the 30 in. parapets. The Fetch Modification Method and the Direct Reduction Method gave relatively similar reductions across the range of upwind fetch distances, while the Simplistic Reduction Method gave larger reductions overall. Reductions in height for the Fetch Modification Method were between 0.25 ft and 0.42 ft, while the Direction Reduction Method returned 0.08 to 0.63 ft and the Simplistic Reduction Method returned 1.61 to 3.09 ft. Due to the large magnitude of reduction estimated by the Simplistic Reduction Method, the method was considered unconservative. From the results of the Fetch Modification Method and Direct Reduction Method, it could be suggested that parapets 30 in. or 48 in. tall could only provide a small amount of leeward drift reduction, roughly 7% to 8% of the original leeward drift height. Further research should be done to expand the heights of parapets examined and to incorporate testing and full scale observations to verify the reduction of the leeward drift.

The first comprehensive study of equatorial- to mid-latitude ionospheric electric fields (plasma drifts) is presented, using extensive incoherent scatter radar measurements from Jicamarca, Arecibo, and Millstone Hill, and F-region ion drift meter data from the polar orbiting DE-2 satellite. Seasonal and solar cycle dependent empirical quiet-time electric field models from equatorial to mid latitudes are developed, which improve and extend existing climatological models. The signatures of electric field perturbations during geomagnetically disturbed periods, associated with changes in the high-latitude currents and the characteristics of storm-time dynamo electric fields driven by enhanced energy deposition into the high-latitude ionosphere, are studied. Analytical empirical models that describe these perturbation drifts are presented. The study provided conclusive evidence for the two basic components of ionospheric disturbance electric fields. It is shown that magnetospheric dynamo electric fields can penetrate with significant amplitudes into the equatorial- to mid-latitude ionosphere, but only for periods up to 1 hour, consistent with results from the Rice Convection Model. The storm-time wind-driven electric fields are proportional to the high-latitude energy input, vary with local time and latitude, and have largest magnitudes during nighttime. These perturbations affect differently the zonal and meridional electric field components. It is shown that equatorial zonal electric fields (vertical drifts) can be disturbed up to 30 hours after large enhancements in the high-latitude currents. These perturbation electric fields are associated with enhanced high-latitude energy deposition taking place predominantly between about 1-12 hours earlier and found to be in good agreement with the Blanc-Richmond disturbance dynamo model. A second class of perturbations occurs around midnight and in the dawn-noon sector with delays of about 18-30 hours between the equatorial- and the high-latitude disturbances , and maximizes during locally quiet geomagnetic times. The latitudinal variation of the meridional disturbance electric fields (zonal drifts) is also presented. It is shown that these perturbation electric fields are predominantly downward/equatorward at all latitudes and due to both prompt penetration and disturbance dynamo electric fields. These results are also generally consistent with predictions from global convection and disturbance dynamo models.

We used ion drift observations from the DE-2 satellite to study for the first time the longitudinal variations of middle and low latitude F-region zonal plasma drifts during quiet and disturbed conditions. The daytime quiet-time drifts do not change much with longitude. In the dusk-premidnight period, the equinoctial middle latitude westward drifts are smallest in the European sector, and the low latitude eastward drifts are largest in the American-Pacific sector. The longitudinal variations of the late night-early morning drifts during June and December solstice are anti-correlated. During geomagnetically active time s, there are large westward perturbation drifts in the late afternoon-early night sector at upper middle latitudes and in the midnight sector at low latitudes. The largest westward disturbed drifts during equinox occur in the European sector and the smallest in the Pacific region. These results suggest that during equinox, Subauroral Polarization Streams (SAPS) events occur most often at European longitudes. The low latitude perturbation drifts do not show significant longitudinal dependence. We have used five years of measurements on board the ROCSA T-1 satellite to develop a detailed local-time, season, and longitude-dependent quiet-time global empirical model for equatorial F-region vertical plasma drifts. We show that the longitudinal dependence of the daytime and nighttime vertical drifts is much stronger than reported earlier, especially during December and June solstice. The late night downward drift velocities are larger in the eastern than in the western hemisphere at all seasons, the morning and afternoon December solstice drifts have significantly different longitudinal dependence, and the daytime upward drifts have strong wavenumber-four signatures during equinox and June solstice. The largest evening upward drifts occur during equinox and December solstice near the American sector. The longitudinal variations of the evening prereversal velocity peaks during December and June solstice are anti-correlated, which further indicates the importance of conductivity effects on the electrodynamics of the equatorial ionosphere. We have shown that disturbance dynamo largely does not affect daytime drifts. The upward perturbations during the nighttime are largely season independent, but near the prereversal enhancement, the downward perturbation drifts are largest during equinox and smallest during December.

Blood is one of the most common biological fluids encountered at crime scenes and is therefore constantly being tested for in the laboratory. Confirming the presence of blood can illuminate essential elements of a case as well as allow for identification via downstream DNA analysis. This significant investigative value is why it is crucial to use robust forensic testing techniques for blood detection. In the forensic laboratory, blood is identified using serological techniques. A presumptive test, such as a colorimetric test, is performed first. A confirmatory test, such as an immunochromatographic assay, is often performed following a presumptive positive result. While both types of tests have numerous advantages, they have several limitations as well. These limitations have served as the basis for exploring alternative techniques for forensic blood detection, such as FTIR. FTIR spectroscopy is a qualitative, non-destructive, confirmatory analytical technique. This technique uses infrared light to characterize organic compounds based on molecular structure. There are also several different FTIR techniques, such as ATR and DRIFTS. ATR-FTIR analysis has been widely researched for the detection of blood and other biological fluids, across several applications. ATR-FTIR may be preferable to serological blood detection because it can be quicker than combined serological blood testing, it requires minimal sample preparation, it does not damage DNA downstream, and it can detect multiple biological fluids at once. Despite all the advantages that ATR-FTIR analysis has over traditional forensic blood techniques, it has not yet been implemented in casework. This may be due to skepticism in using subjective and complex spectroscopic data that results from ATR-FTIR analysis of body fluids. The initial objective of this research was to develop an optimized protocol using ATR-FTIR and chemometric analysis to identify blood on cotton round substrates. Using these techniques together would allow for a rapid, nondestructive, confirmatory approach, that would be more objective than serological testing or FTIR analysis alone. However, due to complications throughout the research process, this objective was altered. The revised objective was to develop an optimized protocol using DRIFTS and chemometric analysis to identify blood on cotton round substrates. An optimized DRIFTS protocol for forensic blood identification was successfully developed. Blood samples from multiple donors were tested using this protocol, and all samples showed similar data. Human biological samples other than blood as well as non-human samples were also tested. These samples showed dissimilar data from the donors’ blood sample data. Chemometric analysis was then performed using AnalyzeIQ Lab software. After testing 93 pair-wise combinations of pre-processing methods and algorithms, a model was developed. Unfortunately, this model was not completely optimized. It had a 9.09% error rate, resulting from the misclassification of one sample. Future research is needed before implementation into casework. Alternative cotton substrates and data collection software should be considered. Additional time should be spent using AnalyzeIQ Lab software, to develop a model with a 0% error rate. If this cannot be achieved, an alternative chemometric analysis software should be considered.

No description available.

Fundação de Amparo a Pesquisa no Estado do Rio Grande do Sul / Ethene or ethylene is a hydrocarbon mainly used in plastic manufacture, through the polymerization. The production of ethene in large scale is performed through cracking process of oil light fractions. In the incessant search of clean and renewable sources to reduce the emission of greenhouse gases, it has been studied the ethylene production with alternative routes. Among the alternative ways of production, the dehydration reaction of ethanol with acid catalysts, like alumina, consists in a very interesting route, since ethanol is widely produced in Brazil, mainly by fermentation of sugarcane juice. However, with relation to the reaction mechanism of the catalytic conversion of the ethanol to ethene, there are some questions when aluminas are used. Therefore, the objective of this work is the study of two metastable forms of aluminas with different acid characteristics, γ- e η-alumina, in order to elucidate the mechanism of dehydration reaction of ethanol to ethene and compare the performance of these two aluminas. For that, two aluminum hydroxides, boehmite and bayerite, were treated in three different temperatures, leading to six catalysts with different acid properties. The catalysts were characterized and in situ reactions with DRIFTS were performed to understand the reaction mechanism. Also, it has studied the reaction kinetics with experiments in laboratory scale unit reaction. With literature information and DRIFTS analysis, some kinetic models were proposed in order to obtain a reaction rate model and to estimate the kinetics parameters. The models presented good adjusts to the experimental data and contributed to the comprehension of the reaction mechanism of ethanol catalytic dehydration. / O eteno ou etileno é um hidrocarboneto utilizado principalmente na fabricação de plásticos, através de sua polimerização. A produção de eteno em larga escala é realizada através do processo de craqueamento de frações leves do petróleo. Na incessante busca por fontes limpas e renováveis para reduzir a emissão de gases poluentes na atmosfera, tem-se o estudo da produção de eteno por rotas alternativas. Dentre os meios alternativos de produção, a reação de desidratação de etanol com catalisadores ácidos, como a alumina, consiste em uma rota muito interessante, já que o etanol é amplamente produzido no Brasil, principalmente através da fermentação do caldo de cana-de-açúcar. No entanto, com relação ao mecanismo reacional da conversão catalítica de etanol em eteno, ainda existem algumas questões quando aluminas são usadas. Portanto, o objetivo deste trabalho é o estudo de duas formas metaestáveis de aluminas com diferentes características ácidas, γ- e η-alumina, a fim de elucidar o mecanismo da reação de desidratação do etanol a eteno e comparar o desempenho das duas aluminas. Para isso, dois hidróxidos de alumínio, boemita e bayerita, foram tratados em três diferentes temperaturas, obtendo-se seis catalisadores com diferentes propriedades ácidas. Os catalisadores foram caracterizados e reações in situ por meio de DRIFTS foram realizadas para compreensão do mecanismo reacional. Ainda, estudou-se a cinética reacional por meio de experimentos em unidade de reações de escala de laboratório. Com informações da literatura e das análises de DRIFTS, alguns modelos cinéticos foram propostos com a finalidade de se obter um modelo de taxa de reação e estimar os parâmetros cinéticos. Os modelos apresentaram um bom ajuste aos dados experimentais e contribuíram na compreensão do mecanismo da reação de desidratação catalítica de etanol.

A transesterificação metílica em meio homogêneo é catalisada por bases, tais como hidróxidos e alcóxidos de sódio ou potássio e se processa em baixa temperatura de reação, mesmo em escala industrial. A utilização de catalisadores formados por sólidos básicos aparece como uma alternativa promissora aos processos homogêneos convencionais, tendo em vista as inúmeras vantagens como a redução da ocorrência das reações indesejáveis de saponificação e redução de custos dos processos pela diminuição do número de operações associadas. Em estudos anteriores realizados pelo grupo, catalisadores a base de Mg/La com diferentes composições químicas (9:1, 1:1 e 1:9) mostraram-se promissores para a obtenção de ésteres metílicos via reação de transesterificação, porém não foi possível fazer uma correlação entre atividade catalítica e as propriedades físico-químicas quando toda a série foi considerada. Assim, a realização de um estudo de caráter fundamental, baseado em reações modelo e uso de moléculas sonda, permite avançar no entendimento das propriedades de superfície destes catalisadores. Portanto, o presente trabalho estuda a reação entre metanol e acetato de etila em catalisadores a base de Mg/La utilizando espectroscopia de reflectância difusa no infravermelho com transformada de Fourier (DRIFTS) acoplada a espectrometria de massas (MS) identificando os intermediários e produtos formados para determinar a rota reacional. As análises de difração de raios X mostram que os precursores são predominantemente compostos por carbonatos hidratados de magnésio (Mg/La 1:1 e 9:1) e de lantânio (Mg/La 1:9). Os perfis de decomposição térmica e difratogramas de raios X obtidos a partir de tratamento térmico in situ indicaram que estes carbonatos se decompõem apenas a partir de 750 C. As análises de Dessorção a Temperatura Programada realizadas com moléculas sonda, metanol e acetato de etila, mostraram a adsorção em maior quantidade do metanol independente da composição química do sólido. A partir dos resultados obtidos por DRIFTS-MS foi proposta uma rota reacional para a reação de transesterificação do acetato de etila e metanol, que ocorre via adsorção do metanol e do acetato de etila na superfície do catalisador, seguida da formação de um intermediário tetraédrico formado pelas moléculas adsorvidas, que sofre um rearranjo formando etanol, acetato de metila, acetona e metano. Simultaneamente, parte do metanol adsorvido como metoxi monodentado é desidrogenado formando formiatos que são dessorvidos na forma de formaldeído e decompostos formando CO2 e H2 / The methylic transesterification of vegetable oils catalyzed by sodium or potassium hydroxides or alkoxides is carried out in homogeneous media at a low reaction temperature, even on an industrial scale. However, the homogeneous reaction has some disadvantages such as the sensitivity of the catalyst to the presence of free fatty acids and/or water in the oil feedstock, which causes the occurrence of undesirable saponification reactions. On the other hand, the use of basic solid catalysts appears as a promising alternative to conventional homogeneous processes, since it reduces the occurrence of undesirable reactions of saponification and decreases the process costs due to the reduction of the number of operations associated. In a previous studies of the group, Mg/La catalysts with different chemical compositions (9:1, 1:1 and 1:9) showed good results for the production of methyl esters via transesterification reaction. However, it was not possible to make a correlation between catalytic activity and the basic properties when the whole series was considered. Therefore, the realization of a fundamental study based on model reactions and the use of probe molecules may lead to the comprehension of the surface properties of these catalysts. Thus, in this work, the reaction between methanol and ethyl acetate catalyzed by a series of Mg/La-catalysts was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupled to mass spectrometry (QMS) aiming at identify the intermediates and products formed to determine the reaction route. The analysis of X-ray diffraction showed that the precursors are mainly hydrated carbonates of magnesium (Mg/La 1:1 and 9:1) and lanthanum (Mg/La 1:9). The TG profiles and in situ X-ray difratograms obtained during the thermal decomposition of the precursors indicate that these carbonates decompose at 750 C or above. Temperature Programmed Desorption analysis carried out with probe molecules, methanol and ethyl acetate, showed a higher amount of methanol adsorbed on the catalyst surface. From the results obtained by DRIFTS-MS a reaction route for the transesterification reaction of methanol and ethyl acetate was proposed. The reaction occurs via adsorption of methanol and ethyl acetate on the catalyst surface. These adsorbed species react forming an adsorbed tetrahedral intermediate which undergoes rearrangement producing ethanol, methyl acetate, acetone and methane. Simultaneously, the methanol adsorbed as a monodentate methoxy specie is dehydrogenated forming formates species that are decomposed in CO2 and H2

A transesterificação metílica em meio homogêneo é catalisada por bases, tais como hidróxidos e alcóxidos de sódio ou potássio e se processa em baixa temperatura de reação, mesmo em escala industrial. A utilização de catalisadores formados por sólidos básicos aparece como uma alternativa promissora aos processos homogêneos convencionais, tendo em vista as inúmeras vantagens como a redução da ocorrência das reações indesejáveis de saponificação e redução de custos dos processos pela diminuição do número de operações associadas. Em estudos anteriores realizados pelo grupo, catalisadores a base de Mg/La com diferentes composições químicas (9:1, 1:1 e 1:9) mostraram-se promissores para a obtenção de ésteres metílicos via reação de transesterificação, porém não foi possível fazer uma correlação entre atividade catalítica e as propriedades físico-químicas quando toda a série foi considerada. Assim, a realização de um estudo de caráter fundamental, baseado em reações modelo e uso de moléculas sonda, permite avançar no entendimento das propriedades de superfície destes catalisadores. Portanto, o presente trabalho estuda a reação entre metanol e acetato de etila em catalisadores a base de Mg/La utilizando espectroscopia de reflectância difusa no infravermelho com transformada de Fourier (DRIFTS) acoplada a espectrometria de massas (MS) identificando os intermediários e produtos formados para determinar a rota reacional. As análises de difração de raios X mostram que os precursores são predominantemente compostos por carbonatos hidratados de magnésio (Mg/La 1:1 e 9:1) e de lantânio (Mg/La 1:9). Os perfis de decomposição térmica e difratogramas de raios X obtidos a partir de tratamento térmico in situ indicaram que estes carbonatos se decompõem apenas a partir de 750 C. As análises de Dessorção a Temperatura Programada realizadas com moléculas sonda, metanol e acetato de etila, mostraram a adsorção em maior quantidade do metanol independente da composição química do sólido. A partir dos resultados obtidos por DRIFTS-MS foi proposta uma rota reacional para a reação de transesterificação do acetato de etila e metanol, que ocorre via adsorção do metanol e do acetato de etila na superfície do catalisador, seguida da formação de um intermediário tetraédrico formado pelas moléculas adsorvidas, que sofre um rearranjo formando etanol, acetato de metila, acetona e metano. Simultaneamente, parte do metanol adsorvido como metoxi monodentado é desidrogenado formando formiatos que são dessorvidos na forma de formaldeído e decompostos formando CO2 e H2 / The methylic transesterification of vegetable oils catalyzed by sodium or potassium hydroxides or alkoxides is carried out in homogeneous media at a low reaction temperature, even on an industrial scale. However, the homogeneous reaction has some disadvantages such as the sensitivity of the catalyst to the presence of free fatty acids and/or water in the oil feedstock, which causes the occurrence of undesirable saponification reactions. On the other hand, the use of basic solid catalysts appears as a promising alternative to conventional homogeneous processes, since it reduces the occurrence of undesirable reactions of saponification and decreases the process costs due to the reduction of the number of operations associated. In a previous studies of the group, Mg/La catalysts with different chemical compositions (9:1, 1:1 and 1:9) showed good results for the production of methyl esters via transesterification reaction. However, it was not possible to make a correlation between catalytic activity and the basic properties when the whole series was considered. Therefore, the realization of a fundamental study based on model reactions and the use of probe molecules may lead to the comprehension of the surface properties of these catalysts. Thus, in this work, the reaction between methanol and ethyl acetate catalyzed by a series of Mg/La-catalysts was studied using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) coupled to mass spectrometry (QMS) aiming at identify the intermediates and products formed to determine the reaction route. The analysis of X-ray diffraction showed that the precursors are mainly hydrated carbonates of magnesium (Mg/La 1:1 and 9:1) and lanthanum (Mg/La 1:9). The TG profiles and in situ X-ray difratograms obtained during the thermal decomposition of the precursors indicate that these carbonates decompose at 750 C or above. Temperature Programmed Desorption analysis carried out with probe molecules, methanol and ethyl acetate, showed a higher amount of methanol adsorbed on the catalyst surface. From the results obtained by DRIFTS-MS a reaction route for the transesterification reaction of methanol and ethyl acetate was proposed. The reaction occurs via adsorption of methanol and ethyl acetate on the catalyst surface. These adsorbed species react forming an adsorbed tetrahedral intermediate which undergoes rearrangement producing ethanol, methyl acetate, acetone and methane. Simultaneously, the methanol adsorbed as a monodentate methoxy specie is dehydrogenated forming formates species that are decomposed in CO2 and H2

Notre dépendance à l'égard des combustibles fossiles et la diminution des ressources pétrolières nous imposent la recherche de sources renouvelables d'énergie et de produits chimiques. La synthèse Fischer-Tropsch permet de répondre à la demande en carburants propres et renouvelables grâce à l'utilisation de gaz de synthèse issu de la biomasse. L'objectif de ce travail est de contribuer à la compréhension du mécanisme de l'hydrogénation du CO sur des catalyseurs au cobalt et à l'identification du site actif par des études spectroscopiques DRIFTS operando. Ce système permet d'observer les différentes espèces adsorbées à la surface du catalyseur pendant la réaction : CO pontés et linéaires, formiates, carboxylates et hydrocarbures. Nos travaux ont montré qu'une fraction des formiates dits « rapides» peut expliquer la formation du méthanol dans nos conditions de réaction. L'ajout dans le mélange H2+CO d'un élément minéral typique de la biomasse, le chlore sous forme de trichloréthylène, a révélé que, l'activité diminuait. La bande des CO pontés étant la plus impactée et se déplaçant vers les hauts nombres d'onde, l'effet du chlore a été notamment associé à un effet électronique sur le cobalt. L'adsorption du chlore étant réversible, nous avons également étudié l'effet de l'étain. Ce métal n'adsorbe pas le CO dans nos conditions et peut s'adsorber à la surface du cobalt. L'étain empoisonne sélectivement la formation des CO pontés et limite fortement la chimisorption de l'hydrogène. Une relation linéaire entre la vitesse de formation des produits et la proportion de CO pontés est observée, révélant l'importance des CO pontés pour la réaction d'hydrogénation du CO / Our dependence on fossil fuels and the decrease of oil resources warrant the search for renewable energy sources and chemicals. Fischer-Tropsch synthesis enables meeting the requirements for cleaner and renewable fuels through the use of syngas obtained from biomass.The objective of this work was to contribute to the understanding of the mechanism of CO hydrogenation on cobalt-based catalysts and the identification of the active site by operando DRIFT spectroscopy. Different species were adsorbed on the surface of the catalyst under reaction conditions: bridged and linear CO, formates, carboxylates and hydrocarbons. Our resutls shows that so-called “fast formate” can account for the formation of methanol under our reaction conditions. The study of a typical biomass element, chlorine, revealed that the activity decreased under trichloroethylene,. The CO bridged band being the most affected band and shifting to higher wavenumber, the chlorine effect was partly associated with an electronic effect on cobalt. Chlorine adsorption being reversible, tin poisoning was also studied. This metal does not adsorb CO under our conditions. Tin addition to cobalt selectively poisons bridged CO and greatly limits the chemisorption of hydrogen. A linear relationship between the rate of formation of products and the proportion of CO bridged is observed, highlighting the importance of CO bridged

The modulation of galactic cosmic ray (GCR) Carbon in a north-south asymmetrical heliosphere is studied, using a two-dimensional numerical model that contains a solar wind termination shock (TS), a heliosheath, as well as particle drifts and diffusive shock re-acceleration of GCRs. The asymmetry in the geometry of the heliosphere is incorporated in the model by assuming a significant dependence on heliolatitude of the thickness of the heliosheath. As a result, the model allows comparisons of modulation in the north and south hemispheres during both magnetic polarity cycles of the Sun, and from solar minimum to moderate maximum conditions. When comparing the computed spectra between polar angles of 55o (approximating the Voyager 1 direction) and 125o (approximating the Voyager 2 direction), it is found that at kinetic energies E < 1:0 GeV/nuc the effects of the assumed asymmetry in the geometry of the heliosphere on the modulated spectra are insignificant up to 60 AU from the Sun, but become increasingly more significant with larger radial distances to reach a maximum inside the heliosheath. In contrast, with E > 1:0 GeV/nuc, these effects remained insignificant throughout the heliosphere even very close to the heliopause (HP). However, when the enhancement of both polar and radial perpendicular diffusion coefficients off the equatorial plane is assumed to differ from heliographic pole to pole, reflecting different modulation conditions between the two hemispheres, major differences in the computed intensities between the two Voyager directions are obtained throughout the heliosphere. The model is further improved by incorporating new information about the HP location and the relevant heliopause spectrum for GCR Carbon at E < 200 MeV/nuc based on the recent Voyager 1 observations. When comparing the computed solutions at the Earth with ACE observations taken during different solar modulation conditions, it is found that it is possible for the level of modulation at the Earth, when solar activity changes from moderate maximum conditions to solar minimum conditions, to exceed the total modulation between the HP and the Earth during solar minimum periods. In the outer heliosphere, reasonable compatibility with the corresponding Voyager observations is established when drifts are scaled down to zero in the heliosheath in both polarity cycles. The effects of neglecting drifts in the heliosheath are found to be more significant than neglecting the enhancement of polar perpendicular diffusion. Theoretical expressions for the scattering function required for the reduction of the drift coefficient in modulation studies are illustrated and implemented in the numerical model. It is found that when this scattering function decreases rapidly over the poles, the computed A < 0 spectra are higher than the A > 0 spectra at all energies at Earth primarily because of drifts, which is unexpected from a classical drift modeling point of view. Scenarios of this function with strong decreases over the polar regions seem realistic at and beyond the TS, where the solar wind must have a larger latitudinal dependence. / PhD (Space Physics), North-West University, Potchefstroom Campus, 2015