3,678 research outputs found
A New Integrated Approach for Fast Intrinsic Dielectric Breakdown
FCT-MCTES Portugal through UID/EEA/00066/2013 is gratefully acknowledged.A non-equilibrium phenomenological description for a complete dielectric breakdown sequence in perfect solid electric insulators, from the dynamics of instability to the growth of branching patterns, is implemented. It represents an original treatment which allows overcoming the current lack of such a complete physical description, involving thermodynamics, and in particular equations on maximum dissipation energy for dielectric breakdown are developed. From the assumption that there is a time delay in the energy rates and propagation speeds between the system input and output, a principle of maximum energy dissipation is postulated and corresponding dynamic evolution equations were obtained. It is shown that the delay in those speeds gives rise to the appearance of iterated equations which in turn leads to the logistic maps describing the dynamic evolution of the system. The results can describe the instability process along with dissipation patterns formation. The vast theoretical and experimental analogies between mechanical fracture and dielectric rupture, lead us to foresee the potential applicability of this model in the prediction of dielectric rupture patterns. This work opens then the possibility to predict the consequent branching patterns by using a maximum energy dissipation principle, contributing in a significant way for energy efficiency engineering.publishersversionpublishe
Quantitative supply chain segmentation model for dynamic alignment
[EN] Companies deal with different customer groups, requirements differ among them, which makes it important to define the service level precisely and improve customer service through different supply chain strategies for each group. An alternative to deal with imprecision related to the segmentation processes suggested by either the Leagile or the Dynamic Alignment Schools is the application of fuzzy set theory. The objective of this work is to develop a quantitative model that uses the fuzzy set theory and, based on sales data, assess the company s supply chain(s). The model's aim is to facilitate managers' decision-making processes to achieve the dynamic alignment. It was possible to identify the supply chains that serve the client groups evaluated, providing answers faster than the analysis proposed by the models found in the literature. The application in two real situations validated the model since the results obtained were consistent with the reality pointed out by the experts of the companies assessed. The model indicates possible actions for the realignment of the supply chain by their managers. Results obtained should improve practice, preparing managers to cope with the organizations` multiple supply chains. This study is the first one that aims to segment quantitatively supply chains on a company applying fuzzy set theory, providing a novel approach to align operations and supply chain strategy dynamically.Alves Ferreira, R.; A. S. Santos, L.; Espôsto, KF. (2022). Quantitative supply chain segmentation model for dynamic alignment. International Journal of Production Management and Engineering. 10(2):99-113. https://doi.org/10.4995/ijpme.2022.16494OJS9911310
Influence of the concentrations of xanthan gum, hydroxypropyl starch and potassium chloride on the flow properties of drilling fluid formulations
Drilling operation of oil wells involves high costs and risks. With recent discoveries of deeper reservoirs and difficult to access, there was an increase in the number of horizontal wells drilled and far-reaching, and, thereat, new challenges with operational problems. Fluids, or muds, drilling are essential to the well drilling process, confirming the need to study and find physical, rheological, and filtration properties, appropriate to the complexities in each section and the drilling stage. Optimized formulation is the one that comprises a safe operation, mitigation of operational problems, environmental protection, low cost, and high productivity. Thus, this paper offers the study of the rheological properties, and determination of filtrate volume, of the aqueous base fluid formulations, developed with polymeric additives. A high performance formulation, presenting technical-economical feasibility for drilling operations, was achieved using 0.43% m/v of viscosifier (xanthan gun), 0.57% m/v of filtrate controller (hydroxypropyl starch) and 4.57% m/v of clay swelling inhibitor (KCl).La operación de perforación de pozos de petróleo implica altos costos y riesgos. Con los recientes descubrimientos de depósitos más profundos y de difícil acceso, hubo un aumento en el número de pozos horizontales perforados y de largo alcance y, por lo tanto, nuevos desafíos con problemas operacionales. Los fluidos o los lodos de perforación son esenciales para el proceso de perforación del pozo, confirmando la necesidad de estudiar y encontrar propiedades físicas, reológicas y de filtración, adecuadas a las complejidades de cada sección ya la fase de perforación. La formulación optimizada es aquella que comprende una operación segura, mitigación de problemas operacionales, protección ambiental, bajo costo y alta productividad. Así, este trabajo ofrece el estudio de las propiedades reológicas y de volumen de filtrado de las formulaciones de fluidos de base acuosa, desarrolladas con aditivos poliméricos. Una formulación de alto rendimiento, presentando viabilidad técnico-económica para operaciones de perforación, fue alcanzada utilizando 0,43% mv de viscosificante (goma xantana), 0,57% m / v de controlador de filtrado (hidroxipropilamido) y 4,57% m / v de inhibidor de la hinchazón de arcilla (KCl)
Citronella essential oil in the control and activation of coffee plants defense response against rust and brown eye spot.
Objetivou-se avaliar o óleo essencial de citronela no controle da ferrugem e cercosporiose e na ativação de respostas de defesa em cafeeiro
BayesMortalityPlus: A package in R for Bayesian graduation of mortality modelling
The BayesMortalityPlus package provides a framework for modelling and
predicting mortality data. The package includes tools for the construction of
life tables based on Heligman-Pollard laws, and also on dynamic linear
smoothers. Flexibility is available in terms of modelling so that the response
variable may be modeled as Poisson, Binomial or Gaussian. If temporal data is
available, the package provides a Bayesian implementation for the well-known
Lee-Carter model that allows for estimation, projection of mortality over time,
and assessment of uncertainty of any linear or nonlinear function of parameters
such as life expectancy. Illustrations are considered to show the capability of
the proposed package to model mortality data
Structural changes in intestinal enteroendocrine cells after ileal interposition in normal rats
INTRODUCTION: No therapeutic approach has significantly impacted the progression of diabetes. As early improvement of glicaemic control is observed after bariatric surgeries, there is currently a search for surgical procedures that can promote euglycemia also in non-obese patients. Glicaemic control can be achieved by increasing the blood concentration of GLP-1, a hormone produced by L cells that are more densely concentrated in the terminal ileum. The interposition of ileal segment to a more anterior region (proximal jejunum) can promote a greater stimulation of the L cells by poorly digested food, increasing the production of GLP-1 and reflecting on glicaemic control.
AIMS: To investigate long-term histological modifications of intestinal mucosa of rats submitted to interposition of ileum segment to a proximal region (jejunum).
METHODS: Forty 8-week old male Wistar-EPM1 rats (Rattus norvegicus albinus) were randomly distributed into 3 groups: the Interposition Group (IG) was subjected to ileal interposition, the Sham Group (SG) was subjected to sham operations, and the Control Group (CG) was not subjected to surgery. All animals were followed until the 60th postoperative day (8 postoperative week) when they were euthanized. Segments of jejunum and ileum from all groups were collected and analyzed by optical microscopy and immunohistochemistry.
RESULTS: No structural nor histological changes in intestinal L cells in the interposed intestinal segment and other intestinal segments were noted after ileal interposition surgery. 
CONCLUSION: As L cells endocrine characteristics were likely maintained, the use of metabolic surgical techniques for the treatment of metabolic diseases, especially diabetes, seems to be justified
Melastomataceae Na Rppn Do Clube Caça E Pesca Itororó, Uberlândia, Mg, Brasil
O presente estudo teve como objetivo o inventário e tratamento taxonômico das Melastomataceae encontradas na RPPN do Clube Caça e Pesca Itororó Uberlândia, MG, Brasil. Durante o estudo foram encontradas 28 espécies distribuídas em 12 gêneros. Miconia é o gênero mais diverso com oito espécies, seguido por Microlicia (quatro spp.), Siphanthera (três spp.), Rhynchanthera, Tibouchina, Trembleya e Leandra (duas spp. cada), Acisanthera, Cambessedesia, Desmoscelis, Lavoisiera e Macairea, com apenas uma espécie cada.43454155
Explanation-by-Example Based on Item Response Theory
Intelligent systems that use Machine Learning classification algorithms are
increasingly common in everyday society. However, many systems use black-box
models that do not have characteristics that allow for self-explanation of
their predictions. This situation leads researchers in the field and society to
the following question: How can I trust the prediction of a model I cannot
understand? In this sense, XAI emerges as a field of AI that aims to create
techniques capable of explaining the decisions of the classifier to the
end-user. As a result, several techniques have emerged, such as
Explanation-by-Example, which has a few initiatives consolidated by the
community currently working with XAI. This research explores the Item Response
Theory (IRT) as a tool to explaining the models and measuring the level of
reliability of the Explanation-by-Example approach. To this end, four datasets
with different levels of complexity were used, and the Random Forest model was
used as a hypothesis test. From the test set, 83.8% of the errors are from
instances in which the IRT points out the model as unreliable.Comment: 15 pages, 5 figures, 3 tables, submitted for the BRACIS'22 conferenc
- …