815 research outputs found
Implicit large-eddy simulation of compressible flows using the Interior Embedded Discontinuous Galerkin method
We present a high-order implicit large-eddy simulation (ILES) approach for
simulating transitional turbulent flows. The approach consists of an Interior
Embedded Discontinuous Galerkin (IEDG) method for the discretization of the
compressible Navier-Stokes equations and a parallel preconditioned Newton-GMRES
solver for the resulting nonlinear system of equations. The IEDG method arises
from the marriage of the Embedded Discontinuous Galerkin (EDG) method and the
Hybridizable Discontinuous Galerkin (HDG) method. As such, the IEDG method
inherits the advantages of both the EDG method and the HDG method to make
itself well-suited for turbulence simulations. We propose a minimal residual
Newton algorithm for solving the nonlinear system arising from the IEDG
discretization of the Navier-Stokes equations. The preconditioned GMRES
algorithm is based on a restricted additive Schwarz (RAS) preconditioner in
conjunction with a block incomplete LU factorization at the subdomain level.
The proposed approach is applied to the ILES of transitional turbulent flows
over a NACA 65-(18)10 compressor cascade at Reynolds number 250,000 in both
design and off-design conditions. The high-order ILES results show good
agreement with a subgrid-scale LES model discretized with a second-order finite
volume code while using significantly less degrees of freedom. This work shows
that high-order accuracy is key for predicting transitional turbulent flows
without a SGS model.Comment: 54th AIAA Aerospace Sciences Meeting, AIAA SciTech, 201
Dimensional reduction applied to an intelligent model for boost converter switching operation
The dimensional reduction algorithms are applied to a hybrid intelligent model that distinguishes the switching operating mode of a boost converter. Thus, the boost converter has been analyzed and both operating mode are explained, distinguishing between Hard-switching and Soft-switching modes. Then, the dataset is created out of the data obtained from simulation of the real circuit and the hybrid intelligent classification model is implemented. Finally, the dimensional reduction of the input variables is carried out and the results are compared. As result, the proposed model with the applied dimensional reduced dataset is able to distinguish between the HS and SS operating modes with high accuracy.ERDF -European Regional Development Fund(ED431G 2019/01
Calidad de servicio y la satisfacción de clientes del distribuidor autorizado de Claro - Grupo Llecllish, Huaraz 2021
La presente investigación titulada “Calidad de servicio y la satisfacción de clientes
del distribuidor autorizado de Claro – Grupo Llecllish, Huaraz 2021”, tuvo como
objetivo determinar la relación entre la calidad de servicio y la satisfacción de
clientes del distribuidor autorizado de Claro – Grupo Llecllish, Huaraz 2021. Contó
con un estudio de tipo aplicada, correlacional con diseño no experimental –
transversal, con una muestra compuesta por 108 clientes, a quienes se les asignó
los cuestionarios. Los resultados identificaron un coeficiente Spearman de 0, 743
determinando una relación positiva alta entre las variables, con una significancia de
0.000 menor a 0.05, aceptándose la hipótesis de investigación.
Llegando a la conclusión que la calidad de servicio en un 76% tuvo niveles altos,
sin embargo, el 19% la calificó con niveles medios. Mientras que la satisfacción de
clientes en un 66% obtuvo niveles altos y el 29% un nivel medio. Finalmente, sobre
la relación de las dimensiones, se identificó que la relación más representativa fue
entre la calidad de servicio y las expectativas, con un coeficiente Spearman de
0,747 y un nivel de significancia bilateral de 0,000 menor al 0,05
Tribological behavior of AA1050H24-graphene nanocomposite obtained by friction stir processing
The tribological behavior of a new composite material containing graphene nanosheets (GNS) is presented. The composite material was obtained by Friction Stir Processing, using as metallic matrix the AA1050-H24 alloy. Different tool rotation and advancing speeds were tested in friction stir processing (FSP). The worn surfaces of obtained materials were analyzed by Scanning Electron Microscopy (SEM). Raman spectroscopy demonstrated that graphene reinforcements are successfully mixed into the aluminum matrix. The results proved the feasibility of using GNSs to obtain nanocomposites by FSP. The coefficient of friction of the aluminum alloy was 0.57, decreasing to 0.38 for the nanocomposite GNSs/AA1050. These values decrease for samples obtained at lower tool rotation speeds. The weight losses of the composites are less than that of unreinforced AA1050-H24 alloy for conditions with lower advancing speeds (40 and 60 mm/min) and 1120 rpm. © 2018 by the authors. Licensee MDPI, Basel, Switzerland
Adjusting MtDNA quantification in whole blood for peripheral blood platelet and leukocyte counts
Alterations of mitochondrial DNA copy number (mtDNAcn) in the blood (mitochondrial to nuclear DNA ratio) appear associated with several systemic diseases, including primary mitochondrial disorders, carcinogenesis, and hematologic diseases. Measuring mtDNAcn in DNA extracted from whole blood (WB) instead of from peripheral blood mononuclear cells or buffy coat may yield different results due to mitochondrial DNA present in platelets. The aim of this work is to quantify the contribution of platelets to mtDNAcn in whole blood mtDNAcn(WB)] and to propose a correction formula to estimate leukocytes'' mtDNAcn mtDNAcn(L)] from mtDNAcn(WB). Blood samples from 10 healthy adults were combined with platelet-enriched plasma and saline solution to produce artificial blood preparations. Aliquots of each sample were combined with five different platelet concentrations. In 46 of these blood preparations, mtDNAcn was measured by qPCR. MtDNAcn(WB) increased 1.07 (95%CI 0.86, 1.29; p<0.001) per 1000 platelets present in the preparation. We proved that leukocyte count should also be taken into account as mtDNAcn(WB) was inversely associated with leukocyte count; it increased 1.10 (95%CI 0.95, 1.25, p<0.001) per unit increase of the ratio between platelet and leukocyte counts. If hematological measurements are available, subtracting 1.10 the platelets/leukocyte ratio from mtDNAcn(WB) may serve as an estimation for mtDNAcn(L). Both platelet and leukocyte counts in the sample are important sources of variation if comparing mtDNAcn among groups of patients when mtDNAcn is measured in DNA extracted from whole blood. Not taking the platelet/leukocyte ratio into account in whole blood measurements, may lead to overestimation and misclassification if interpreted as leukocytes'' mtDNAcn
Oxidized LDL Is Associated With Metabolic Syndrome Traits Independently of Central Obesity and Insulin Resistance
This study assesses whether oxidative stress, using oxidized LDL (ox-LDL) as a proxy, is associated with metabolic syndrome (MS), whether ox-LDL mediates the association between central obesity and MS, and whether insulin resistance mediates the association between ox-LDL and MS. We examined baseline data from 3,987 subjects without diabetes in the Progression of Early Subclinical Atherosclerosis (PESA) Study. For the second, third, and fourth ox-LDL quartiles versus the first, the odds ratios (95% CI) for MS were 0.84 (0.52, 1.36), 1.47 (0.95, 2.32), and 2.57 (1.66, 4.04) (P < 0.001 for trend) once adjusted for age, sex, smoking, LDL-cholesterol, BMI, waist circumference, and HOMA-insulin resistance (HOMA-IR). Results showing the same trend were found for all MS components except glucose concentration. Ox-LDL mediated 13.9% of the association of waist circumference with triglycerides and only 1-3% of the association with HDL-cholesterol, blood pressure, and insulin concentration. HOMA-IR did not mediate the association between ox-LDL and MS components. This study found higher ox-LDL concentrations were associated with MS and its components independently of central obesity and insulin resistance. Ox-LDL may reflect core mechanisms through which MS components develop and progress in parallel with insulin resistance and could be a clinically relevant predictor of MS development.Y.H.-R. received support from Republic of Peru and the Inter-American Development Bank through FINCyT Science and Technology Program Scholarships No. 088-FINCyT-BDE-2014 under agreement 1663/OC-PE. M.L. received partial support from the Institute de Salud Carlos III, cofunded by the European Regional Development Fund/European Social Fund, "Investing in Your Future" grants PI10/00021 and PI14/00009. The PESA study is supported by a noncompetitive unrestricted grant shared between the CNIC and Santander Bank. The CNIC is supported by the Spanish Ministry of Economy and Competitiveness (MINECO) and the Pro-CNIC Foundation and is a Severo Ochoa Center of Excellence (MINECO award SEV-2015-0505).S
Network-wide abnormalities explain memory variability in hippocampal amnesia
Patients with hippocampal amnesia play a central role in memory neuroscience but the neural underpinnings of amnesia are hotly debated. We hypothesized that focal hippocampal damage is associated with changes across the extended hippocampal system and that these, rather than hippocampal atrophy per se, would explain variability in memory between patients. We assessed this hypothesis in a uniquely large cohort of patients (n = 38) after autoimmune limbic encephalitis, a syndrome associated with focal structural hippocampal pathology. These patients showed impaired recall, recognition and maintenance of new information, and remote autobiographical amnesia. Besides hippocampal atrophy, we observed correlatively reduced thalamic and entorhinal cortical volume, resting-state inter-hippocampal connectivity and activity in posteromedial cortex. Associations of hippocampal volume with recall, recognition, and remote memory were fully mediated by wider network abnormalities, and were only direct in forgetting. Network abnormalities may explain the variability across studies of amnesia and speak to debates in memory neuroscience
Enantioselective Synthesis of 2-Amino-1,1-diarylalkanes Bearing a Carbocyclic Ring Substituted Indole through Asymmetric Catalytic Reaction of Hydroxyindoles with Nitroalkenes
[EN] An asymmetric catalytic reaction of hydroxyindoles with nitroalkenes leading to the Friedel-Crafts alkylation in the carbocyclic ring of indole is presented. The method is based on the activating/directing effects of the hydroxy group situated in the carbocyclic ring of the indole providing nitroalkylated indoles functionalizated at the C-4, C-5, and C-7 positions with high yield, regio-, and enantioselectivity. The optically enriched nitroalkanes were transformed efficiently in optically enriched 2-amino-1,1-diarylalkanes bearing a carbocyclic ring substituted indole.Financial support from the MINECO (Gobierno de Espana; CTQ2017-84900-P) is gratefully acknowledged. C.V. thanks MINECO for a JdC contract. J.R.-B. thanks the Ministry of Education for a Collaboration grant. Access to NMR, MS, and X-ray facilities from the Servei Central de Suport a la Investigacio Experimental (SCSIE)-UV is also acknowledgedVila, C.; Rostoll-Berenguer, J.; Sánchez-García, R.; Blay, G.; Fernandez, I.; Muñoz Roca, MDC.; Pedro, JR. (2018). Enantioselective Synthesis of 2-Amino-1,1-diarylalkanes Bearing a Carbocyclic Ring Substituted Indole through Asymmetric Catalytic Reaction of Hydroxyindoles with Nitroalkenes. The Journal of Organic Chemistry. 83(12):6397-6407. https://doi.org/10.1021/acs.joc.8b0061263976407831
“Let’s Go Engineering”
Let’s Go Engineering nace del análisis de la situación actual en España,
donde faltan profesionales de la ingeniería para cubrir las necesidades del mercado.
Adicionalmente a ésto encontramos la falta de diversidad en el mundo de la
ingeniería. Con esto in mente y tras llevar a cabo algunas charlas en centros
educativos de Primaria y Secundaria sobre esta problemática, un equipo de
Schneider Electric decidió impulsar y desarrollar de forma voluntaria 'Let's Go
Engineering', un programa dirigido a estudiantes en últimos cursos de la escuela
primaria, cuyo objetivo es colaborar activamente con los centros educativos de las
principales ciudades españolas, para crear un espacio de influencia y así contribuir
a despertar vocaciones de ingeniería y romper los estereotipos de género asociados
a estas carreras. El programa 'Let's Go Engineering' se realiza durante un curso
escolar y se compone de varias fases, a lo largo de las cuales se realizan
diferentes actividades que pretenden despertar la creatividad de los estudiantes y
mostrar el impacto humanitario y beneficio social de la tecnología. Cada clase
incluida en el programa se prepara de forma conjunta entre el equipo que integra
'Let's Go Engineering' y el profesorado en las aulas. Además, se hace un
acompañamiento a las familias a través de las AMPAs, para que sean conocedores
de la realidad, contribuyan a romper estereotipos y sean también agentes del
cambio en la mentalidad de las nuevas generaciones. 'Let's Go Engineering', inició
el mes de septiembre 2018, con una periodicidad variable de las imparticiones de
actividades de entre 15 días y un mes. El programa cuenta con un equipo de más
de 40 voluntarios de Schneider Electric y con la colaboración de profesores
especializados, universidades públicas como la Universitat Politècnica de Catalunya
(UPC), y empresas Partners de Schneider Electri
- …