Genetic algorithms are well known for being expensive optimization tools, especially if the cost for the analysis of each individual design is high. In the past few years, significant effort has been put forth in addressing the high computational cost GAs. The research conducted in the first part of this thesis continues this effort by implementing new multiple elitist and variable elitist selection schemes for the creation of successive populations in the genetic search process. The new selection schemes allow the GA to take advantage of a greater amount of important genetic information that may be contained in the parent designs, information that is not utilized when using a traditional elitist method selection scheme. By varying the amount of information that may be passed to successive generations from the parent population, the explorative and exploitative characteristics of the GA can be adjusted throughout the genetic search also. The new schemes provided slight reductions in the computational cost of the GA and produced many designs with good fitness' in the final population, while maintaining a high level of reliability. Genetic algorithms can be easily adapted to many different optimization problems also. This capability is demonstrated by modifying the basic GA, which utilizes a single chromosome string, to include a second string so that composite laminates comprised of multiple materials can be studied with greater efficiently. By using two strings, only minor adjustments to the basic GA were required. The modified GA was used to simultaneously minimize the cost and weight of a simply supported composite plate under different combinations of axial loading. Two materials were used, with one significantly stronger, but more expensive than the other. The optimization formulation was implemented by using convex combinations of cost and weight objective functions into a single value for laminate fitness, and thus required no additional modifications to the GA. To obtain a Pareto-optimal set of designs, the influence of cost and weight on the overall fitness of a laminate configuration was adjusted from one extreme to the other by adjusting the scale factors accordingly. The modified GA provided a simple yet reliable means of designing high performance composite laminates at costs lower than laminates comprised of one material. / Master of Science

Ground penetrating radar (GPR) is limited by the depth of penetration and signal-to-noise ratio (SNR), which both impact the ability to resolve subsurface features. GPR antennas are known to have limited depth penetration due to the noise and signal attenuated. The noise floor is the depth at which there is no discernable signal (Stec and Susek 2018). SNR is the comparison of desired signal to background noise, understanding that noise is any unwanted signal. Different objects in the environment can transmit frequencies that are recorded in data as background noise; this noise is considered to be external noise. Internal noise is noise which is generated by the internal components of the GPR system. Data processing such as filtering can reduce noise. Noise that occurs at the same frequency as the signal of interest, however, cannot be filtered out without also removing the signal of interest.

No description available.

No description available.

Machine learning has been a subject undergoing intense study across many different industries and academic research areas. Companies and researchers have taken full advantages of various machine learning approaches to solve their problems; however, vast understanding and study of the field is required for developers to fully harvest the potential of different machine learning models and to achieve efficient results. Therefore, this thesis begins by comparing auto ml with other hyper-parameter optimization techniques. auto ml is a fully autonomous framework that lessens the knowledge prerequisite to accomplish complicated machine learning tasks. The auto ml framework automatically selects the best features from a given data set and chooses the best model to fit and predict the data. Through multiple tests, auto ml outperforms MLP and other similar frameworks in various datasets using small amount of processing time. The thesis then proposes and implements a stacking ensemble technique in order to build protection against over-fitting for small datasets into the auto ml framework. Stacking is a technique used to combine a collection of Machine Learning models’ predictions to arrive at a final prediction. The stacked auto ml ensemble results are more stable and consistent than the original framework; across different training sizes of all analyzed small datasets. / Master of Science

A Eletroforese Capilar (CE) é uma técnica de separação baseada na migração diferenciada de compostos iônicos ou ionizáveis em um campo elétrico, proporcionando alta resolução, eficiência e rapidez de análise. Para preservar a alta resolução, o volume injetado deve ser pequeno (da ordem de nanolitros), o que dificulta a análise de compostos em baixos níveis de concentração. O diminuto caminho óptico definido pelo diâmetro interno do capilar, associado ao pequeno volume injetado, compromete a detecção, principalmente quando se utiliza a absorbância em linha. Várias estratégias têm sido descritas para melhorar a sensibilidade em eletroforese capilar. Neste trabalho, as estratégias de pré-concentração (\"stacking\", amplificação de campo, isotacoforese, cela óptica de alta sensibilidade e extração em fase sólida em linha) foram aplicadas a dois sistemas químicos: o ácido tereftálico (matéria prima importante utilizada na síntese de poliésteres) e o besilato de atracúreo (um agente bloqueador neuromuscular), avaliando-se comparativamente os resultados. O primeiro sistema não se mostrou adequado para tai fim, pois o ácido tereftálico apresenta baixa solubilidade em água, sendo necessário adicionar hidróxido de sódio para dissolvê-lo, o que produzia um meio de alta condutividade, inviabilizando algumas das estratégias de pré-concentração. Porém, como o controle de impurezas no ácido tereftálico é de interesse industrial foi desenvolvido um método para a análise simultânea dos subprodutos principais: o ácido carboxibenzaldeído (4-CBA) e o ácido p-toluóico (pTO), que são controlados industrialmente por polarografia e cromatografia à gás, respectivamente. As análises foram realizadas em lotes industriais do ácido tereftálico cru (CTA) e do ácido tereftálico altamente purificado (PTA). As concentrações de 4-CBA e p-TOL (determinadas por CE) em ambos, CTA e PTA, estão de acordo com as especificações do produto. As análises mostraram a viabilidade da determinação das impurezas, sendo identificados ainda o ácido benzóico (BZ) e o 4-hidroximetilbenzóico (HMB). O segundo sistema químico escolhido, o besilato de atracúreo, foi adequado para avaliar as várias estratégias de pré-concentração, pois este composto é solúvel em água. A apresentação comercial deste produto consiste na mistura de três isômeros (cis-cis, cis-trans e trans-trans), cada um exibindo uma potência bloqueadora neuromuscular particular. Primeiramente foi desenvolvido um método para a separação dos três isômeros por CE e depois foi feito um estudo das impurezas presentes no sistema, avaliando-se a temperatura e o tempo de estocagem. Foram identificadas duas impurezas no composto: a laudanosina e o monoquaternário ácido. Foi escolhido o pico da laudanosina para avaliar as estratégias de aumento de sensibilidade devido este ser o principal composto de decomposição do atracúreo. O aumento de sensibilidade foi calculado em termos de ganho em sinal-ruído (S/R). O melhor resultado de aumento de sensibilidade para o \"stacking\" mediado por força iônica foi quando se dissolveu a amostra em água e comparou-se à mesma amostra dissolvida no tampão de corrida (o ganho em S/R foi da ordem de 25 vezes). Para as demais estratégias, a referência de partida foi uma amostra já dissolvida em água. Dentre todas as estratégias avaliadas, o maior ganho em sensibilidade foi obtido com os pré-concentradores (22,5 vezes de aumento em sinal-ruído (S/R)), mas a dificuldade de confecção não os tornam atrativos para as análises. A isotacoforese proporcionou o segundo maior aumento (7,6 vezes), comparável ao aumento de sensibilidade em campo amplificado (7,5 vezes) quando se utilizou um tampão com alta concentração de sal. Este ganho foi melhor que o da cela HS que teve aumento de 2,9 vezes em SIR, sugerindo que estas técnicas de pré-concentração podem ser utilizadas com vantagem em relação à cela HS proporcionando baixo custo. O aumento de sensibilidade não foi tão expressivo no \"stacking\" por injeção de grande volume (1,1), mas pode ser melhorado se o capilar inteiro for preenchido com a amostra. / Capillary Electrophoresis (CE) is a separation technique based on differential migration of ionic compounds in a electric field, providing high efficiency, resolution and faster analysis. To preserve high resolution, the injected volume must be small (nanoliters), which compromises the analysis of samples components in a low concentration level. The little pathlenght defined by the capillary internal diameter and a small injected volume, place a large demand on detection, especially when on-line absorbance detectors is used. Some strategies have been described to improve the capillary electrophoresis sensitivity. At this work, preconcentration techniques (stacking, field amplification, isotachophoresis, high sensitivity optical cell, and on line solid extraction) were applied to two chemical systems: terephthalic acid (an important raw material used in a polyester synthesis) and atracurium besylate (a neuromuscular blocking agent), and the results were comparatively evaluated. The first selected system was not suitable for this purpose, due to poor solubility of terephthalic acid in water. lt was necessary to work with solutions of crude and purified products prepared in 0.15 mol /L NaOH and that produced a high conductivity medium, jeopardizing some preconcentration techniques. However, since impurities control in terephthalic acid is of industrial interest, it was developed a method to simultaneously analyze major byproducts: 4-carboxybenzaldehyde (4-CBA) and toluoic acid (pTO), industrialy controlled by polarography and gas chromatography, respectively. Analysis were conducted in industrial batches of crude terephthalic acid (CTA) and highly purified terephthalic acid (PTA). Concentrations of 4-CBA and p-TOL, in both, CTA and PTA, were in agreement with product specification. The results showed the viability to determine several impurities using CE. Additionally, two other contaminants, benzoic acid (BZ) and 4-hydroxymethyl benzoic acid (HMB), were identified. The second selected system, atracurium besylate, was useful to evaluate some preconcentration strategies, because of this water solubility and ionic character. Commercial presentation of this pharmaceutical consists in a mixture of three isomers (cis-cis, cis-trans e trans-trans), which one presenting a particular neuromuscular potency. First, it was developed a method to separate the three isomers by CE and then a study of the product impurities was conducted, evaluating the temperature tolerance and shelf life. Laudanosine and a monoquaternary acid were identified impurities in the pharmaceutical. Laudanosine was selected for the evaluation of preconcentration techniques because it is the major decomposition product of atracurium besylate. Sensitivity enhancement was calculated in terms of signal-noise increase (S/R). The best results of enhancement sensitivity with \"stacking\" mediated by ionic strange was obtained when the sample was dissolved in water and it was compared to the same sample dissolved in a running buffer (signal-noise increase was 25 times). To the other strategies, the reference sample was dissolved in water). Among all evaluated strategies, the major sensitivity enhancement was obtained with preconcentrators (22,5 times), but its difficult manufaturing makes them not attractive for routine analysis. Isotachophoresis, the second best in terms of signal-noise (S/R) values (7,6 times), was comparable to field amplification sensitivity enhancement (7,5 times), when buffers with high salt concentration were used. Its enhancement was better than that of HS cell, that was signal-noise increase of 2,9 times), suggesting that these preconcentration techniques can be used with advantage in relation to HS cell providing low cost. Sensitivity enhancement was not expressive, in the large injection volumes strategy (1, 1 times), but it can be improved if the whole capillar1 is filled with sample.

A Eletroforese Capilar (CE) é uma técnica de separação baseada na migração diferenciada de compostos iônicos ou ionizáveis em um campo elétrico, proporcionando alta resolução, eficiência e rapidez de análise. Para preservar a alta resolução, o volume injetado deve ser pequeno (da ordem de nanolitros), o que dificulta a análise de compostos em baixos níveis de concentração. O diminuto caminho óptico definido pelo diâmetro interno do capilar, associado ao pequeno volume injetado, compromete a detecção, principalmente quando se utiliza a absorbância em linha. Várias estratégias têm sido descritas para melhorar a sensibilidade em eletroforese capilar. Neste trabalho, as estratégias de pré-concentração (\"stacking\", amplificação de campo, isotacoforese, cela óptica de alta sensibilidade e extração em fase sólida em linha) foram aplicadas a dois sistemas químicos: o ácido tereftálico (matéria prima importante utilizada na síntese de poliésteres) e o besilato de atracúreo (um agente bloqueador neuromuscular), avaliando-se comparativamente os resultados. O primeiro sistema não se mostrou adequado para tai fim, pois o ácido tereftálico apresenta baixa solubilidade em água, sendo necessário adicionar hidróxido de sódio para dissolvê-lo, o que produzia um meio de alta condutividade, inviabilizando algumas das estratégias de pré-concentração. Porém, como o controle de impurezas no ácido tereftálico é de interesse industrial foi desenvolvido um método para a análise simultânea dos subprodutos principais: o ácido carboxibenzaldeído (4-CBA) e o ácido p-toluóico (pTO), que são controlados industrialmente por polarografia e cromatografia à gás, respectivamente. As análises foram realizadas em lotes industriais do ácido tereftálico cru (CTA) e do ácido tereftálico altamente purificado (PTA). As concentrações de 4-CBA e p-TOL (determinadas por CE) em ambos, CTA e PTA, estão de acordo com as especificações do produto. As análises mostraram a viabilidade da determinação das impurezas, sendo identificados ainda o ácido benzóico (BZ) e o 4-hidroximetilbenzóico (HMB). O segundo sistema químico escolhido, o besilato de atracúreo, foi adequado para avaliar as várias estratégias de pré-concentração, pois este composto é solúvel em água. A apresentação comercial deste produto consiste na mistura de três isômeros (cis-cis, cis-trans e trans-trans), cada um exibindo uma potência bloqueadora neuromuscular particular. Primeiramente foi desenvolvido um método para a separação dos três isômeros por CE e depois foi feito um estudo das impurezas presentes no sistema, avaliando-se a temperatura e o tempo de estocagem. Foram identificadas duas impurezas no composto: a laudanosina e o monoquaternário ácido. Foi escolhido o pico da laudanosina para avaliar as estratégias de aumento de sensibilidade devido este ser o principal composto de decomposição do atracúreo. O aumento de sensibilidade foi calculado em termos de ganho em sinal-ruído (S/R). O melhor resultado de aumento de sensibilidade para o \"stacking\" mediado por força iônica foi quando se dissolveu a amostra em água e comparou-se à mesma amostra dissolvida no tampão de corrida (o ganho em S/R foi da ordem de 25 vezes). Para as demais estratégias, a referência de partida foi uma amostra já dissolvida em água. Dentre todas as estratégias avaliadas, o maior ganho em sensibilidade foi obtido com os pré-concentradores (22,5 vezes de aumento em sinal-ruído (S/R)), mas a dificuldade de confecção não os tornam atrativos para as análises. A isotacoforese proporcionou o segundo maior aumento (7,6 vezes), comparável ao aumento de sensibilidade em campo amplificado (7,5 vezes) quando se utilizou um tampão com alta concentração de sal. Este ganho foi melhor que o da cela HS que teve aumento de 2,9 vezes em SIR, sugerindo que estas técnicas de pré-concentração podem ser utilizadas com vantagem em relação à cela HS proporcionando baixo custo. O aumento de sensibilidade não foi tão expressivo no \"stacking\" por injeção de grande volume (1,1), mas pode ser melhorado se o capilar inteiro for preenchido com a amostra. / Capillary Electrophoresis (CE) is a separation technique based on differential migration of ionic compounds in a electric field, providing high efficiency, resolution and faster analysis. To preserve high resolution, the injected volume must be small (nanoliters), which compromises the analysis of samples components in a low concentration level. The little pathlenght defined by the capillary internal diameter and a small injected volume, place a large demand on detection, especially when on-line absorbance detectors is used. Some strategies have been described to improve the capillary electrophoresis sensitivity. At this work, preconcentration techniques (stacking, field amplification, isotachophoresis, high sensitivity optical cell, and on line solid extraction) were applied to two chemical systems: terephthalic acid (an important raw material used in a polyester synthesis) and atracurium besylate (a neuromuscular blocking agent), and the results were comparatively evaluated. The first selected system was not suitable for this purpose, due to poor solubility of terephthalic acid in water. lt was necessary to work with solutions of crude and purified products prepared in 0.15 mol /L NaOH and that produced a high conductivity medium, jeopardizing some preconcentration techniques. However, since impurities control in terephthalic acid is of industrial interest, it was developed a method to simultaneously analyze major byproducts: 4-carboxybenzaldehyde (4-CBA) and toluoic acid (pTO), industrialy controlled by polarography and gas chromatography, respectively. Analysis were conducted in industrial batches of crude terephthalic acid (CTA) and highly purified terephthalic acid (PTA). Concentrations of 4-CBA and p-TOL, in both, CTA and PTA, were in agreement with product specification. The results showed the viability to determine several impurities using CE. Additionally, two other contaminants, benzoic acid (BZ) and 4-hydroxymethyl benzoic acid (HMB), were identified. The second selected system, atracurium besylate, was useful to evaluate some preconcentration strategies, because of this water solubility and ionic character. Commercial presentation of this pharmaceutical consists in a mixture of three isomers (cis-cis, cis-trans e trans-trans), which one presenting a particular neuromuscular potency. First, it was developed a method to separate the three isomers by CE and then a study of the product impurities was conducted, evaluating the temperature tolerance and shelf life. Laudanosine and a monoquaternary acid were identified impurities in the pharmaceutical. Laudanosine was selected for the evaluation of preconcentration techniques because it is the major decomposition product of atracurium besylate. Sensitivity enhancement was calculated in terms of signal-noise increase (S/R). The best results of enhancement sensitivity with \"stacking\" mediated by ionic strange was obtained when the sample was dissolved in water and it was compared to the same sample dissolved in a running buffer (signal-noise increase was 25 times). To the other strategies, the reference sample was dissolved in water). Among all evaluated strategies, the major sensitivity enhancement was obtained with preconcentrators (22,5 times), but its difficult manufaturing makes them not attractive for routine analysis. Isotachophoresis, the second best in terms of signal-noise (S/R) values (7,6 times), was comparable to field amplification sensitivity enhancement (7,5 times), when buffers with high salt concentration were used. Its enhancement was better than that of HS cell, that was signal-noise increase of 2,9 times), suggesting that these preconcentration techniques can be used with advantage in relation to HS cell providing low cost. Sensitivity enhancement was not expressive, in the large injection volumes strategy (1, 1 times), but it can be improved if the whole capillar1 is filled with sample.

No description available.

This dissertation focuses on the design and study of charged aromatic molecules where weak π-π interactions synergize with electrostatic interactions to enhance the overall interaction between aromatic moieties. Each chapter investigates some aspect of this hypothetical synergy between electrostatics and π-face aromatic cohesion. The first chapter unveiled the importance of electrostatics in the intramolecular stacking of flexible aromatic molecular templates 1-2Br and 2a. While our previous studies found dicationic molecular template 1-2Br to have intramolecular π-stacking between electron poor pyridinium and electron rich xylylene moieties, no such stacking interaction was observed in the neutral analog 2a. Chapter two systematically explored the stacking pattern of electron poor aromatics in the form of oxygen- and / or nitrogen- substituted triangulenium cations, [1(NR)3]+ and [1(O)3(OH)3]+. As indicated in the chemical literature, triazatriangulenium cations [1(NR)3]+ with N- ethyl (and longer alkyl chains) chains were found to pack as face-to-face dimers. This study found the formation of columnar, face-to-face, n-meric association between aromatic cations in the structures with decreased steric interactions of the side chains in the stacking planes ([1(NMe)3]+ and [1(O)3(OH)3]+). Similar iso-structural triangulene based aromatic anions, (2)- and (3)2- didn’t indicate any facial interactions in the solid states. The possible synergy between unit charge electrostatics and π-face aromatic interactions was explored in aromatic ion pairs 1•2 of triangulene based aromatic cations and aromatic anions. This charge-assisted π-π stacking seems to be the novel way of getting strong π-system interactions where the strongest non-covalent force and the weakest non-covalent force: ionic bonding and π-stacking respectively synergize together. The π-π interaction between ionic aromatics in the solid state was investigated by means of single crystal x-ray diffraction and powder x-ray diffraction (PXRD). The interaction in the solution state was examined by UV-Vis spectroscopy, electrospray ionization mass spectroscopy (ESI-MS) and electrochemical studies. Studies found that optimal synergy was possible only in the ion pairs with no steric interactions of alkyl (or aryl) side chains in the stacking planes (1(O)3•2 & 1(NMe)3•2) and the interaction was found to be comparable with the strongest radical-assisted π-stacking described in the chemical literature.

Blazare sind aktive galaktische Kerne mit relativistischen Plasmajets, deren Symmetrieachse in Richtung Erde zeigt. Sie sind primäre Kandidaten für die Produktion von hochenergetischen Neutrinos. Diese Arbeit umfasst die Suche nach einem kumulativen Neutrinofluss von allen 862 Fermi-LAT 2LAC Blazaren und vier spektral ausgewählten Unterpopulationen. Selektierte Myonspuren aus drei Jahren IceCubedaten werden mit einer ungebinnten "Stacking"-Punktquellenanalyse untersucht. Zwei unterschiedliche Gewichtungen werden benutzt, um den unbekannten relativen Anteil jeder Quelle am Gesamtneutrinofluss der jeweiligen Population zu berücksichtigen. Neun der zehn resultierenden Tests zeigen leichte Überfluktuationen, von denen keine statistisch signifikant ist. Das Ergebnis erlaubt es, den Maximalanteil der 2LAC-Blazare zum kürzlich entdeckten astrophysikalischen TeV-PeV Neutrinofluss auf 23% einzuschränken. Diese Grenze gilt unter der Annahme des momentan favorisierten Spektralindex des astrophysikalischen Neutrinoflusses von -2.5 und bei einem Flavorverhältnis von 1:1:1 bei Erreichen der Erde. Die Ergebnisse erfordern keine rein hadronische Produktion der beobachteten Gammastrahlung und bleiben, bis auf einen Faktor zwei, für moderat härtere Spektren oder für kleinere Unterpopulationen, wie z.b. die GeV-detektierten TeVCat Quellen, gültig. Zusätzlich werden obere Flussgrenzen für generische Spektren, die einem Potenzgesetz folgen, sowie für konkrete spektrale Modelle der diffusen Neutrinoemission von Blazaren, ausgerechnet. 12 von 14 dieser Modelle können eingeschränkt oder ausgeschlossen werden. Wenn die größte Überfluktuation als physikalischer Effekt interpretiert wird, findet man einen weichen Fluss in der 5-10 TeV Region, welcher mit Gammastrahlenbeobachtungen kompatibel ist. Mehr Daten sind bereits verfügbar und erlauben es, dieses Szenario in der nahen Zukunft zu testen. / Blazars are active galactic nuclei with relativistic plasma jets whose symmetry axis is pointing towards Earth. They are a prime source candidate for the production of high-energy neutrinos. This work describes the search for a cumulative neutrino flux from all 862 Fermi-LAT 2LAC blazars and four spectrally defined sub-populations. Selected muon-track events from three years of IceCube data are analyzed with an unbinned likelihood stacking approach. Two different weighting schemes are used to account for the unknown relative flux contributions of each source. Nine of ten tests show slight overfluctuations, none of which are statistically significant. An upper flux limit is calculated constraining the maximal contribution of the 2LAC blazars to the recently discovered diffuse TeV-PeV neutrino flux to be 23% or less assuming the currently favored spectral index for the astrophysical flux of around −2.5 and an equal composition of neutrino flavors arriving at Earth. The results do not require a purely hadronic production of the observed gamma rays and remain valid for moderately harder spectra or smaller sub-populations, e.g. the TeVCat sub-sample, up to a factor of around 2. Additionally, upper limits are calculated for generic power-law spectra and for concrete spectral models of the diffuse neutrino emission of blazar populations. 12 out of 14 of these models are either constrained or excluded. If the largest overfluctuation is interpreted as a physics effect, one finds a soft flux in the 5-10 TeV region that is compatible with gamma-ray observations. Further years of data are already available which makes this scenario testable in the near future. If confirmed, blazars might become the first known extragalactic hadronic acceleration site.