13 research outputs found
Advanced models for free vibration analysis of laminated beams with compact and thin-walled open/closed sections
No full textIn this paper, refined one-dimensional beam theories are implemented for the free vibration analysis of laminated beams with compact and thin-walled cross-sections. The proposed models are based on the Carrera Unified Formulation, which was formerly introduced for the analysis of plates and shells and recently extended to beam structures by the first author and his co-workers. Carrera Unified Formulation is a hierarchical modelling technique leading to very accurate and computationally efficient finite element theories. According to the latest developments in the framework of Carrera Unified Formulation, refined beam models are implemented using either Taylor-like or Lagrange-like polynomials in order to expand the unknown kinematic variables on the cross-section of the beam. Equivalent single layer models result from the former approach. On the other hand, if Lagrange polynomials are used, layer-wise models are produced. In this work, a classical one-dimensional finite element formulation along the beam length is used to develop numerical applications. A number of laminated beam structures are analyzed, and particular attention is given to laminated box beams with open and closed cross-sections. The frequencies and the mode shapes obtained with the present refined beam elements are compared with solid/shell finite element solutions from the commercial code MSC/Nastran and, when possible, with those found in the literature. The modal assurance criterion is used for model-to-model comparisons so as to demonstrate the enhanced capabilities of the proposed formulation in investigating the free vibration characteristics of both compact and thin-walled box laminated beam
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EVALUATION OF SOCCER BALL PROPERTIES AND THEIR EFFECT ON THE BRAIN
No full textSoccer is the most popular sport in the world, with an estimated 250 million active players worldwide and 3.5 billion spectators. The fundamental equipment needed for the game is the soccer ball. Due to its wide popularity soccer is played by all age groups, including men and women. Soccer is a contact sport where collisions can occur directly between players, head to ground contact, head to goal post contact, ball to head contact, etc. Soccer is a unique sport because it allows players to deliberately and purposely direct the ball with their heads—a technique known as "heading”. Since heading is a component of the game, this study examines the brain response to different head impacts using biofidelic models. The effect of different mechanical properties soccer ball during heading on brain response is investigated and identify the ways to reduce the brain injury due to heading.Soccer balls have been tested in laboratory conditions against rigid surfaces but have not been correlated to play conditions with recoiling impact surfaces. The experimental study compared the laboratory speed to play conditions and evaluated the impact of ball pressure on kicked ball speed. The average kicked ball speed increased from increased the ball pressure within the manufacturers recommended limits. For a shot on goal from 11 meters, this led to 13.5 mm less goalkeeper movement.Assessment of the risk of brain injury from ball heading in soccer was performed by numerical simulations of the ball head impact using a biofidelic Total Human Model for Safety (THUMS) model. A comparison was made between the effect on brain response to different impact locations, ball pressure, ball speed, and ball friction. Oblique impacts were the most severe, compared to normal and side impacts, producing 74% more maximum principal strain than normal impacts in the cerebellum region. The impact from a high ball speed at low ball pressure posed a greater risk of brain injury than a low-speed ball with high ball pressure. A 14% increase in ball speed increased the maximum principal strain by 25% and for a 25% increase in ball pressure, the maximum principal strain is increased by 7% in brain stem. For oblique impacts, the coefficient of friction was important. When friction increased from its lowest to its highest level, the brain experienced 130% more strain.The effect of the player size on brain response was investigated by comparing the brain response of three different sizes of biofidelic models. The result showed that a 95th percentile model experienced 36% less strain than the 5th percentile model. Balls weighing 435 gm and 290 gm were projected towards a 50th percentile model with the same energy. With the lighter ball (290 gm), more strain in the brain (up to 30%) was observed.Due to the popularity of soccer, it is played by both genders and children. The brain response of the male and female players was compared in this study. Total Human Model for Safety (THUMS) male 50th percentile whiplash model and female 50th percentile whiplash model were used to compare the brain response of teams of mixed gender. For the same ball pressure and speed, the linear and rotational acceleration of the 50th percentile female model increased by 44% and 16%, respectively, compared to the 50th percentile male model. For 35% less ball pressure and the same ball velocity, the 50th percentile female model shown 23% more linear acceleration and 2% less linear rotational acceleration than the 50th percentile male model. THUMS 5th percentile female model which is equivalent to 50th percentile 12-year youth is used to simulate the ball head impact with different ball sizes (size 4 and size 5). For the same energy of the balls before impact the size 4 ball impact produced 32% more linear acceleration and 26% more rotational acceleration
Properties of solutions to some weighted p-Laplacian equation
No full textIn this paper, we prove some qualitative properties for the positive solutions to some degenerate elliptic equation given by-div (w|∇u|p-2∇u) = f(x, u), u ∈ Ap, on smooth domain and for varying nonlinearity f.Peer reviewe
Unveiling the Farming dynamics: A comparative analysis of arecanut and tea cultivation done by small farmers in Udalguri district of Assam
No full textThis research paper evaluates the cultivation practices, economic contributions, and social impact of areca nut and tea cultivation done by small farmers in the Suklai village of Udalguri district of Assam, India, in a comparative manner. This study is based on field surveys and interaction with farmers and labourers, carried out concerning certain major factors such as income generation, cost of cultivation, soil and water usage, pest management, and impact on social welfare. Results indicated that each crop had different sources of profitability, resource requirements, and social benefits for many people. Areca nut cultivation is a more income-stable and less resource-dependent type of cultivation; thus, it remains a favorite option for many farmers. On the other hand, tea cultivation is more laborious and resource-demanding but is marked by social and cultural benefits. The work reported here should provide valuable information to policymakers and people engaged in agriculture to develop sustainable farming practices that will lead to improving the lives of farmers in Udalguri
Existence and nonexistence results for anisotropic p-Laplace equation with singular nonlinearities
No full textLet pi≥ 2 and consider the following anisotropic p-Laplace equation −∑Ni=1∂∂xi(∣∣∂u∂xi∣∣pi−2∂u∂xi)=g(x)f(u),u>0 in Ω. Under suitable hypothesis on the weight function g we present an existence result for f(u)=e1u in a bounded smooth domain Ω and nonexistence results for f(u)=−e1u or −(u−δ+u−γ), δ,γ>0 with Ω=RN respectively.Peer reviewe
Weak Harnack inequality for a mixed local and nonlocal parabolic equation
No full textPublisher Copyright: © 2023 The Author(s)This article proves a weak Harnack inequality with a tail term for sign changing supersolutions of a mixed local and nonlocal parabolic equation. Our argument is purely analytic. It is based on energy estimates and the Moser iteration technique. Instead of the parabolic John-Nirenberg lemma, we adopt a lemma of Bombieri-Giusti to the mixed local and nonlocal parabolic case. To this end, we prove an appropriate reverse Hölder inequality and a logarithmic estimate for weak supersolutions.Peer reviewe
Zotero – An Open-Source Reference Management Software: A Practical Manual
No full textTitle of the Book: Libraries and Open Science: Issues Challenges and Opportunities;
Author(s): Edited by S K Sonkar and M P Singh;
Publisher: Ess Ess Publications, New Delhi;
Year of Publication: 2022;
Pages: 310-324
Morphology of Plants Using Spatial Domain Image Enhancement Technique for the Mildew Detection
No full textUnsteady solute dispersion in the presence of reversible and irreversible reactions
No full textIn an unsteady pulsatile non-Newtonian fluid past a tube with a thin wall layer, the dispersion of a narrow uniform slug of injected solute over a cross-section is examined. At the interface between the mobile fluid phase and the immobile wall phase, both irreversible and reversible reactions have been adopted. The Carreau-Yasuda model is used to describe the fluid's rheology. The impacts of fluid rheology and reaction parameters on the concentration profiles in the fluid- and wall-phases and the three transport coefficients, viz, the depletion coefficient (K-0), the convection coefficient (K-1), the dispersion coefficient (K-2) in the fluid phase are predicted numerically. A considerable shift in the behaviour of K-1 and K(2 )with a higher reaction rate may be observed in the transient stage. The axial dispersion of mobile-phase concentration in the unsteady Carreau-Yasuda II fluid model is significantly larger than in Poiseuille and steady Carreau-Yasuda II fluid models, and flow pulsatility on the immobile-phase concentration is prominent upstream at a longer time. In addition, the peak value of the mobile-phase section-mean concentration is consistently lower than in other fluid models. This study could help researchers to understand the drug delivery in blood vessels and pulmonary mechanical ventilation. (C) 2022 The Author(s) Published by the Royal Society. All rights reserved
High perturbations of quasilinear problems with double criticality
No full textFunding Information: Claudianor O. Alves was partially supported by CNPq/Brazil 304804/2017-7. The work of Vicenţiu D. Rădulescu was supported by a grant of the Romanian Ministry of Education and Research, CNCS-UEFISCDI, Project number PN-III-P4-ID-PCE-2020-0068, within PNCDI III. Vicenţiu D. Rădulescu was also supported by the Slovenian Research Agency program P1-0292. Publisher Copyright: © 2021, The Author(s). Copyright: Copyright 2021 Elsevier B.V., All rights reserved.This paper is concerned with the qualitative analysis of solutions to the following class of quasilinear problems {-ΔΦu=f(x,u)inΩ,u=0on∂Ω,where ΔΦu=div(φ(x,|∇u|)∇u) and Φ(x,t)=∫0|t|φ(x,s)sds is a generalized N-function. We assume that Ω ⊂ RN is a smooth bounded domain that contains two open regions Ω N, Ω p with Ω ¯ N∩ Ω ¯ p= ∅. The features of this paper are that - Δ Φu behaves like - Δ Nu on Ω N and - Δ pu on Ω p, and that the growth of f: Ω × R→ R is like that of eα|t|NN-1 on Ω N and as |t|p∗-2t on Ω p when |t| is large enough. The main result establishes the existence of solutions in a suitable Musielak–Sobolev space in the case of high perturbations with respect to the values of a positive parameter.Peer reviewe
