14,685 research outputs found
Planar phonon anisotropy, and a way to detect local equilibrium temperature in graphene
No full textThe effect of inclusion of the planar phonon anisotropy on thermo-electrical behavior of graphene is analyzed. Charge transport is simulated by means of Direct Simulation Monte Carlo technique coupled with numerical solution of the phonon Boltzmann equations based on deterministic methods.The definition of the crystal lattice local equilibrium temperature is investigated as well and the results furnish possible alternative approaches to identify it starting from measurements of electric current density, with relevant experimental advantages, which could help to overcome the present difficulties regarding thermal investigation of graphene.Positive implications are expected for many applications, as the field of electronic devices, which needs a coherent tool for simulation of charge and hot phonon transport; the correct definition of the local equilibrium temperature is in turn fundamental for the study, design and prototyping of cooling mechanisms for graphene-based devices
Coupled Monte Carlo–Deterministic simulation of thermal behavior of graphene on substrate
No full textThe purpose of this paper is to study thermal effects in a graphene sheet on substrate. The temperature evolution of the phonon branches and of the crystal lattice is obtained when also the presence of the substrate is taken into account. The numerical strategy is based on the coupling of stochastic and deterministic numerical methods; Boltzmann equation for charge transport is treated by using the Direct Simulation Monte Carlo approach, whose results are treated as source terms for the phonon Boltzmann equation which is solved deterministically. The results are useful also for applications as correct design of graphene-based prototypes, when heating effects in the presence of a substrate are relevant
On the Kelvin–Voigt model in anisotropic viscoelasticity
No full textWe propose an anisotropic and nonlinear generalization of the Kelvin–Voigt viscoelastic model obtained considering the additive splitting of the Cauchy stress tensor in an elastic and a dissipative part. The former one corresponds to a fiber-reinforced hyperelastic material while the dissipative effect is described by the most general linear transverse-isotropic tensorial function of symmetric part of the velocity gradient. In a such a way we characterize the dissipative contribution via three viscoelastic moduli. We then show, by a detailed analysis of the simple shear quasistatic motion and the corresponding creep phenomena, that this motion may be used to determine experimentally the viscoelastic parameters
Superposing plane strain on anti-plane shear deformations in a special class of fiber-reinforced incompressible hyperelastic materials
No full textThe purpose of the present research is to investigate how the nonlinearity and the boundary conditions have the power to influence the coupling of the various modes of deformation when a plane strain deformation is superimposed on anti-plane shear deformation for a class of fiber-reinforced incompressible hyperelastic materials described by a strain energy density W. Attention is confined when W depends only on the first invariant of the strain tensor and on the square of the stretch in the direction of the fibers. We are able to write down the governing equations of equilibrium as a coupled system of three nonlinear partial differential equations for three displacement fields. Two displacements are the in-plane components and one displacement is the anti-plane state. The system that we are able to deduce in a compact form is always compatible at variance with the case in which the anti-plane shear problem is analyzed. As explicit example of our findings we study the problem of the helical shear and we investigate into details the coupling of its axial and azimuthal components
Estudio de la fabricación ladrillo bloque en concreto reforzado con fibras de coco
No full textPara la modalidad de grado escogida (análisis sistemático de literatura) se elaboró el artículo académico ESTUDIO DE LA FABRICACIÓN LADRILLO BLOQUE EN CONCRETO REFORZADO CON FIBRAS DE COCO y conjuntamente se realizó el envió para optar a una aceptación y publicación en la revista de ingeniería científica y desarrollo de la universidad del Norte. Teniendo en cuenta que el artículo dirige su enfoque e investigación a las fibras vegetales en el cual se sintetiza la caracterización de la inclusión de las fibras de coco como material ligero no convencional, analizando los comportamientos arrojados por las investigaciones de las autoras Jenny Díaz Lozano C,; Castro Espinosa A. P,; Bolaños Henao M. L.; en su tesis “Fabricación y estudio del ladrillo bloque en concreto reforzado con fibras de coco”Objetivos -- Objetivos específicos -- Introducción -- Marco teórico -- Antecedentes -- Marco referencial -- Marco legal -- Justificación -- Metodología -- Resultados -- Resumen -- Introducción -- Metodología -- Resultados -- Conclusiones -- Referencias-- Conclusiones -- Referencia
Influencia de ceniza de mesocarpio de coco sobre la subrasante de la carretera la Huaca – Las Peñas, Huabal, Jaén, 2024
No full textLa investigación tuvo como objetivo evaluar la influencia de la ceniza de mesocarpio de coco sobre la subrasante de la carretera La Huaca – Las Peñas, Huabal, la metodología consistió encontrar las propiedades físicas y mecánicas del suelo, seguido realizar CBR con cenizas. Los resultados demostraron que la C-1 y C-2, presentaron suelos A-2-5(0) arena limosa; y las C-3, C-4, C-5 y C-6 subrasantes arenas arcillosas A-2-4(0). Al incluir al suelo 0%, 3%, 5%, 7% y 9% de cenizas de mesocarpio de coco, la C-1/C-2 tuvo densidades máximas secas de 1.712, 1.702, 1.724, 1.785 y 1.761gr/cm3; óptimos contenidos de humedad de 20.10%, 22.5, 21.5, 20.37 y 21.40; valores de CBR al 95% de la MDS a 0.1” de 6.63, 15.70, 24.20, 25.40 y 41.56%; de otro lado la C-3 / C-4 / C-5 / C-6, la densidad fue de 1.944, 1.945, 1.947, 1.955 y 1.975gr/cm3; la humedad de 14.80, 13.80, 13.40, 12.90 y 13.50%; y el CBR de 8.10, 52.73, 55.10, 81.50 y 58.73%. Concluyó que la óptima adición para la C-1/C-2 fue con el 9% y para la C-3 / C-4 / C-5 / C-6 con el 7%; generando un impacto positivo en la estabilización de suelos de características inadecuadas
Charge and Phonon Transport in Suspended Monolayer Graphene
No full textThermal effectsThermal effectsare playing a crucial role for the design of electron nanoscale devices. The present contribution deals with charge and phonon transport under an applied external electric field in a suspended monolayer of graphene. A major question is represented by the phonon-phonon collision operator involving in general a three particle scattering mechanism. To model the phonon-phonon interactions a relaxation time approximation is employed. This requires the introduction of a local equilibrium phonon temperature whose definition is still a matter of debate for a general non equilibrium situation. Here, two different approaches are presented and discussed
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