Effect of One Supplementation Period of Methylsulfonylmethane and Glucosamine on Some Antioxidants Following a Plyometric Exercise Session

Background: Intensive physical activity results in release of free radicals and oxidative damages in biomacromolecules. Consumption of sulfuric supplements may effect on the levels of oxidative stress following intensive exercises. Therefore, the effect of six weeks combined supplementation of methylsulfonylmethane and glucosamine on the glutathione peroxidase and catalase following a plyometric exercise session in amutor male athletes was studied in the present study. Materials and Methods: The study was a double-blinded quasi-experimental reseach with a pre- and post-test design in which 22 amateur male athletes (age mean: 26.18±4.02 years old; height: 176.00±4.10 cm; weight: 83.70±10.43 kg) were randomly assigned into two groups of supplement (n = 11) and placebo (n = 11), and participated in two bouts of plyometric exercise before and after the supplementation period. The supplementation period included daily consumption of 3 miligrams/bw combined methylsulfonylmethane and glucosamine for six weeks. The serum levels of Glutathione Peroxidase and Catalase enzymes were determined before and after the two plyometric exercise sessions, and the collected data were analyzed using analysis of covariance (ANCOVA) at p<0.05 significant level. Results: After controlling the effects of the initial levels, the levels of glutathione peroxidase and catalase enzymes after exercise for the supplement group were higher than the placebo group (respectively, F2,9= 71.73, p=0.001 and F2,9= 191.76, p=0.001). Conclusion: Combined supplementation of methylsulfonylmethane and glucosamine may increase anti-oxidant capacity in athletes through increased levels of glutathione peroxidase and catalase enzymes

Friction stir welding of AA2024-T3: development of numerical simulation considering thermal history and heat generation

This paper proposes a finite element model implemented in ANSYS using Lagrangian formulation to assess heat generation and friction dynamics of a friction stir welding process on AA2024-T3 aluminum plates. For that aim, the model is enriched by estimating a temperature-dependent friction coefficient using theoretical relationships, and by considering a temperaturedependent multilinear isotropic hardening equation as a plasticity model representing the material. Both quantitative determinations are confirmed through experimental data collected on the real material. Finally, the contact conditions are modeled using the modified Coulomb criterion. The results of the model are in agreement with actual results observed on experimental applications. The study proves that the rotational speed of the tool is the most determinant factor in the results. As it rises, the friction-generated heat flow is higher. This study shows that the compressive stress-strain data in strain rate of 10s-1 is a good approximation of the plasticity behavior of aluminum alloy during the friction stir welding.Peer ReviewedObjectius de Desenvolupament Sostenible::9 - Indústria, Innovació i InfraestructuraPostprint (author's final draft

Estimating sheet flow velocities using quinine as a fluorescent tracer: bare, mulched, vegetated and paved surfaces

When direct flow velocity measurements are not feasible, the use of tracers can be a valuable tool. In the present study, both laboratory and field experiments were conducted to evaluate the applicability of quinine as a fluorescent tracer for estimating mean sheet flow velocities in different ambient light and surface morphology conditions. Quinine excels in low-light conditions when exposed to UVA light. This tracer was compared with dye and thermal tracers, all in liquid form. In these tracing techniques the tracers were injected into the flow, after which surface velocity was estimated by tracking the leading edge of the tracer plumes and applying a correction factor to calculate the mean velocity (in a water column). The visibility of the tracers was evaluated by measuring the relative luminance and contrast ratio of the quinine and dye tracer plumes. Results show that the quinine tracer can be used to estimate sheet flow velocities over a wide variety of soil and urban surfaces; it has better visibility in comparison to the dye tracer but, in some conditions, lower visibility than the thermal tracer. Although quinine is invisible under bright ambient light conditions, this tracer technique requires low-cost experimental setup and is useful in low-light conditions (e.g., night; twilight; shielded environments).info:eu-repo/semantics/publishedVersio

FATIGUE STRENGTH OF A CHASSIS OF A SEMI-HEAVY TRUCK UNDER DYNAMIC LOADS DUE TO REAL ROAD ROUGHNESS

Evaluation of fatigue life of vehicles by using a real road test is very expensive; therefore, numerical methods such as Finite Element Method (FEM) are nowadays very popular for evaluating fatigue life. In this study, a method based on FEM is proposed for predicting fatigue strength of the chassis when designing and optimizing a semi-heavy truck. An experimental modal analysis has been applied for the validation of the finite element model which has been used in the proposed method. The natural frequencies and mode shapes of the chassis have been obtained from the finite element analysis and compared with the corresponding results of the experimental modal analysis. Also, a method for producing uneven roads in the time domain based on the International Reference Index (IRI) was introduced to simulate road roughness. In addition, different road types (with potholes and kerbs) and different load conditions (braking and cornering) have been considered throughout the simulation. In all of the mentioned conditions, stress time histories have been extracted and investigated. Finally, fatigue damage and strength of the chassis and welded connections have been estimated and described

Using quinine as a fluorescent tracer to estimate overland flow velocities on bare soil: Proof of concept under controlled laboratory conditions

This study presents a tracer technique based on the fluorescent properties of quinine to help on the visualization of shallow flows and allow a quantitative measurement of overland flow velocities. Laboratory experiments were conducted to compare the traditional dye tracer and thermal tracer techniques with this novel fluorescent (quinine) tracer by injecting a quinine solution and the other tracers into shallow flowing surface water. The leading-edge tracer velocities, estimated using videos of the experiments with the quinine tracer were compared with the velocities obtained by using thermograms and real imaging videos of the dye tracers. The results show that the quinine tracer can be used to estimate both overland and rill flow velocities, since measurements are similar to those resulting from using other commonly used tracers. The main advantage of using the quinine tracer is the higher visibility of the injected tracer under ultraviolet A (UVA) light for low luminosity conditions. In addition, smaller amounts of quinine tracer are needed than for dye tracers, which lead to smaller disturbances in the flow. It requires a simple experimental setup and is non-toxic to the environment.UIDB/04292/2020info:eu-repo/semantics/publishedVersio

Ratcheting of plain pressurized cylinders subjected to seismic bending moments

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN021256 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Numerical and Experimental Study of Flow in Open Channels with Cylindrical Roughness

Documentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeirosIn this study effect of the different types of surface roughness on a turbulent boundary layer was studied using 1D velocity measurements in a relatively high Reynolds free-Surface water channel. The roughness consisted cylindrical ribs with several P/D (P is the roughness spacing, D is the roughness height). The roughness elements were aligned in a direction transverse to the flow. The experiments involve one-dimensional flow velocity, water surface profiles and bed pressures and forces with different Reynolds numbers. A series of 12 tests of fully rough turbulent subcritical flow over two dimensional transverse repeated cylindrical ribs was undertaken in which the ribs were varied to give uniform rib spacing-toheight ratios of P/D = 5-20. The results show that the normalized velocity U+ for all the surfaces has significantly decreased comparing to smooth bed. The average values of the drag Cf and friction Ft coefficients are reduced with increasing of roughness distances on rough beds, also the amount of the drag and friction coefficients are the highest values on the cylindrical roughness with P/D= 15, H= 8 cm, D= 6 mm. Flow development in an openchannel with rough beds was investigated using FLUENT. The RNG k-ε turbulence model was used for subcritical flow cases. The volume of fluid (VOF) method was used to allow the free-surface to deform freely with the underlying turbulence. The main purpose of this study is to examine the effects of surface roughness on a turbulent boundary layer in a relatively different Reynolds numbers. The determination of velocity profile in turbulent open channels with rough bed is a difficult task due to the significant effects of the roughness. The velocity distributions in the log-region for the rough wall were determined and the roughness function U+, was evaluated compared to the smooth bed. The results show that the mean profiles of all the surfaces collapse well in the velocity defect form

Studying the Effect of Fillet on Fretting Fatigue Strength in the Press-Fitted Axle Assembly using Different Multiaxial Fatigue Criteria and Fretting Fatigue Damage Darameter

The present paper studies the effect of creating a fillet on fretting fatigue strength of an axle, using different multiaxial fatigue criteria and fretting fatigue damage parameter. Finite element method is applied to obtain stress and strain in the axle and the results obtained from modeling are compared with the experimental test data available in literature. The results show that fretting fatigue strength of the axle and fracture area depends on the ratio of&nbsp; diameter to fillet radius. Multiaxial fatigue criteria is almost capable of estimating the fatigue strength of the axle . However; the results obtained from investigating fretting fatigue damage parameter are almost in accordance with the results of experimental data and consequently fretting fatigue damage parameter can be appropriately used as a criterion for estimating fretting fatigue strength of the axles

Fatigue life estimation for different notched specimens based on the volumetric approach

In this paper, the effects of notch radius for different notched specimens has been studied on the values of stress concentration factor, notch strength reduction factor, and fatigue life duration of the specimens. The material which has been selected for this investigation is Al 2024T3 . Volumetric approach has been applied to obtain the values of notch strength reduction factor and results have been compared with those obtained from the Neuber and Peterson methods. Load controlled fatigue tests of mentioned specimens have been conducted on the 250kN servo-hydraulic Zwick/Amsler fatigue testing machine with the frequency of 10Hz. The fatigue lives of the specimens have also been predicted based on the available smooth S-N curve of Al2024-T3 and also the amounts of notch strength reduction factor which have been obtained from volumetric, Neuber and Peterson methods. The values of stress and strain around the notch roots are required to predict the fatigue life of notched specimens, so Ansys finite element code has been used and non-linear analyses have been performed to obtain the stress and strain distributions around the notches. The plastic deformations of the material have been simulated using multi-linear kinematic hardening and cyclic stress-strain relation. The work here shows that the volumetric approach does a very good job for predicting the fatigue life of the notched specimens