36 research outputs found
A determinant approach for generalized -Bernoulli polynomials and asymptotic results
No full textIn earlier work, we introduced three families of polynomials where the
generating function of each set includes one of the three Jackson -analogs
of the Bessel function. This paper gives determinant representation for each
family, their large asymptotics, and two expansion theorems for specific
classes of entire functions. We include two examples
Multi-fidelity Design of Porous Microstructures for Thermofluidic Applications
No full textAs modern electronic devices are increasingly miniaturized and integrated,
their performance relies more heavily on effective thermal management.
Two-phase cooling methods enhanced by porous surfaces, which capitalize on
thin-film evaporation atop structured porous surfaces, are emerging as
potential solutions. In such porous structures, the optimum heat dissipation
capacity relies on two competing objectives that depend on mass and heat
transfer. The computational costs of evaluating these objectives, the high
dimensionality of the design space which a voxelated microstructure
representation, and the manufacturability constraints hinder the optimization
process for thermal management. We address these challenges by developing a
data-driven framework for designing optimal porous microstructures for cooling
applications. In our framework we leverage spectral density functions (SDFs) to
encode the design space via a handful of interpretable variables and, in turn,
efficiently search it. We develop physics-based formulas to quantify the
thermofluidic properties and feasibility of candidate designs via offline
simulations. To decrease the reliance on expensive simulations, we generate
multi-fidelity data and build emulators to find Pareto-optimal designs. We
apply our approach to a canonical problem on evaporator wick design and obtain
fin-like topologies in the optimal microstructures which are also
characteristics often observed in industrial applications.Comment: 24 pages, 10 figure
A Modified Gravimetric Method for Measuring Rates of Vapor Adsorption and Desorption on Soils. Kinetics of Toluene Adsorption/Desorption on Bentonite
No full textProbabilistic Neural Data Fusion for Learning from an Arbitrary Number of Multi-fidelity Data Sets
No full textIn many applications in engineering and sciences analysts have simultaneous
access to multiple data sources. In such cases, the overall cost of acquiring
information can be reduced via data fusion or multi-fidelity (MF) modeling
where one leverages inexpensive low-fidelity (LF) sources to reduce the
reliance on expensive high-fidelity (HF) data. In this paper, we employ neural
networks (NNs) for data fusion in scenarios where data is very scarce and
obtained from an arbitrary number of sources with varying levels of fidelity
and cost. We introduce a unique NN architecture that converts MF modeling into
a nonlinear manifold learning problem. Our NN architecture inversely learns
non-trivial (e.g., non-additive and non-hierarchical) biases of the LF sources
in an interpretable and visualizable manifold where each data source is encoded
via a low-dimensional distribution. This probabilistic manifold quantifies
model form uncertainties such that LF sources with small bias are encoded close
to the HF source. Additionally, we endow the output of our NN with a parametric
distribution not only to quantify aleatoric uncertainties, but also to
reformulate the network's loss function based on strictly proper scoring rules
which improve robustness and accuracy on unseen HF data. Through a set of
analytic and engineering examples, we demonstrate that our approach provides a
high predictive power while quantifying various sources uncertainties
Role of Volatilization in Changing TBA and MTBE Concentrations at MTBE-Contaminated Sites
No full textTertiary butyl alcohol (TBA) is commonly found as an
impurity in methyl tertiary butyl ether (MTBE) added to
gasoline. Frequent observations of high TBA, and especially
rising TBA/MTBE concentration ratios, in groundwater at
gasoline spill sites are generally attributed to microbial
conversion of MTBE to TBA. Typically overlooked is the role
of volatilization in the attenuation of these chemicals
especially in the vadose zone, which is a source of
contamination to groundwater. Here we show that
volatilization, particularly through remediation by vapor
extraction, can substantially affect the trends in TBA and
MTBE concentrations and the respective mass available
to impact groundwater aquifers, through the preferential
removal of more volatile compounds, including MTBE, and
the apparent enrichment of less volatile compounds like
TBA. We demonstrate this phenomenon through numerical
simulations of remedial-enhanced volatilization. Results
show increases in TBA/MTBE concentration ratios consistent
with ratios observed in groundwater at gasoline spill
sites. Volatilization is an important, and potentially dominant,
process that can result in concentration trends similar
to those typically attributed to biodegradation
Síntese, caracterização e avaliação do potencial biológico de derivados obtidos a partir de chalconas
No full textTese (doutorado) - Universidade Federal de Santa Catarina, Centro de Ciências Físicas e Matemáticas. Programa de Pós-Graduação em Química.The chalcones is one of the biggest classes of natural products. The research and drug development consist of a complex and long process that begin with the basic research of a new active compound in pre-clinical models. The condensation of aldehydes and ketones is particularly interesting for the reactions of organic synthesis, the presence of the á, â-unsaturated function together with the type and position of substituent in aromatic rings are often related to biological activity by these compounds. This study describes the synthesis of chalcones derivatives with structural modifications, as well as pyrazolines, sulphonylpyrazolines, hydrazones, urenyl- and thiourenyl-chalcones and evaluation in biological models. The pirazolines, sulphonylpyrazolines and hydrazones derivatives were obtained by the reaction between the appropriated hydrazines and different substituted chalcones, whereas the urenyl- and thiourenyl-chalcones were obtained by the reaction of aldolic condensation of Claisen-Schmidt between thiourenyl- and urenylaminoacetophenones previously synthesized and differents benzaldehydes. All the compounds were evaluated in distinct models of pain, in mice, and some of them also were evaluated in microbiological models (antibacterial, antifungal and antiparasite). The antinociceptive evaluation of chalcones derivatives demonstrated a promising profile, with emphasis on the compounds 60, 68, 85, and 97, which evaluated activity was more potent than reference drugs. None of the compounds tested presented antibacterial or antifungal activities against the pathogenic microorganism tested. Among the compounds evaluated in antiparasite models, only compounds 68 and 92 presented significative results against T. cruzi; and all the pirazolines synthesized, compound 68 and 92 presented activity against L. amazonensis. The promising chemical and biological results demonstrated here the viability of using the studied classes to achieve more active substances, which might present new therapeutic possibilities. A condensacao de aldeidos e cetonas e especialmente interessante para as reacoes de sintese organica. A presenca da funcao ¿,À-insaturada, juntamente com o tipo e posicao do substituinte nos aneis aromaticos, estao frequentemente relacionados a atividade biologica associada a estes de derivados atraves de modificacoes estruturais do esqueleto chalconico, entre eles podemos citar as pirazolinas, sulfonilpirazolinas, hidrazonas, urenil- e tiourenilchalconas. As pirazolinas, sulfonilpirazolinas e hidrazonas foram obtidas atraves de reacoes entre as chalconas previamente sintetizadas e diferentes fenilidrazinas, ja as urenil- e tiourenil-chalconas foram sintetizadas atraves da reacao de condensacao aldolica de Claisen-Schmidt entre as urenil- e tiourenilaminoacetofenonas previamente sintetizadas e diferentes benzaldeidos. Todos os derivados sintetizados foram avaliados no modelo antinociceptivo in vivo do acido acetico, e alguns deles tambem foram avaliados em outros modelos de dor e em modelos microbiologicos (antibacterianos, antifungicos e antiparasitarios). Os derivados sintetizados apresentaram promissor efeito antinociceptivo, com destaque para a pirazolina 60, a sulfonilpirazolina 68, a hidrazona 85 e a tioureia 97, cuja atividade foi superior aos valores obtidos para os farmacos de referencia. Os derivados nao foram ativos frente aos patogenos (fungos e bacterias) avaliados nos ensaios microbiologicos. Dentre os derivados avaliados nos modelos antiparasitarios, todas as pirazolinas, a sulfonilpirazolina 68 e a tioureia 92 apresentaram resultados significativos contra L. amazonensis, os compostos 68 e 92 tambem foram ativos contra T. cruzi. Os promissores resultados quimicos e farmacologicos aqui demonstrados viabilizam a utilizacao das classes quimicas estudadas na representacao de novas possibilidades terapeuticas
