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The first and second laws of the thermodynamics were applied to the human body to evaluate the performance of subjects under different training levels. Ten cyclists were evaluated in the stationary bicycle with the indirect calorimetry analysis to obtain the metabolism on an energy and exergy basis. A distinguishing feature of this article is the evaluation of the exergy efficiency of the body with...
Nowadays, the surface texture of tool is an attractive machining technique due to the benefits in any chip removal machining process performance. However, surface texture design on texture tool plays a significant role in improving the turning process performance, in this context, a novel hybrid surface texture design has been proposed in the current work. The present work focused on the machinability...
In this paper, the transient dynamic stress intensity factors are estimated for multiple cracks which are located at the interface between a nonhomogeneous elastic half-plane and an elastic half-plane. The material properties of the nonhomogeneous half-plane vary continuously in the y-direction. First, Laplace and Fourier transforms are applied to reduce the mixed boundary value problem to a system...
The vibration fatigue characteristics of a beam structure with breathing cracked links are studied, with the consideration of the contact forces at the breathing crack surfaces. First, a dynamic model of the breathing cracked beam element was formulated using the finite element method (FEM) and the theory of fracture mechanics. Subsequently, the coupled dynamic equation of a beam structure with breathing...
The dynamic characteristics of structures (beams and plates) can be significantly changed by embossing small out-of-plane patterns in these structures. Recent results in literature show, both numerically and experimentally, that shaping a beam in the geometry of its first mode shape significantly increases the value of the first natural frequency of the beam. This phenomenon also occurs when the beam...
The formulation of a stability criterion is crucial to perform safe, versatile and efficient biped gaits for robots. We here present a stability criterion for non-cyclic gait synthesis, the Predicted Step Viability, inspired by human gait and N-Step Capturability. The Predicted Step Viability defines the constraints of the current step such that future steps will be able to guarantee convergence to...
This paper addresses the kinematical and dynamical analyses of a novel linearly actuated 4-DOF parallel kinematic machine, composing 3 translational and 1 rotational motion abilities. For this purpose, first, based on the closed loop vector theorem, the inverse kinematical relations of position, velocity and acceleration are derived. Then, employing the Euler’s method, dynamics of the mechanism is...
In this study, the fluid hammer of viscoelastic flow in pipes is studied numerically. Here, the Oldroyd-B model is used as the constitutive equation. This model is suitable for dilute viscoelastic solutions and Boger liquids. The numerical solution is obtained using a two-step variant of the Lax–Friedrichs (LxF) method. The derived equations are non-dimensionalized, and the effect of Deborah and Reynolds...
Railway turnouts are elements exposed to an accelerated track degradation when compared to plain line track. The particular and complex wheel/rail contact characteristics in railway turnouts make the contact forces acting on the wheel/rail interface particularly high. As a consequence of the train/track interaction force magnitude, track degradation is more accelerated here, having a big impact on...
This paper proposes analytical approximations for solving extended Graetz problems with axial diffusion in infinite domains. A general formulation, valid for both parallel-plates channels and circular ducts, is employed, and a discontinuous Dirichlet condition is applied at the wall. The adopted methodology consists of transforming the 2D convection equation into simpler one-dimensional forms, using...
To apply abrasive slurry jet (ASJ) in rock drilling calls for in-depth understandings on the mechanism of impingement process. A fluid–structure coupling model that combines multi-fluid model and finite element method was established for a set of numerical investigation. The simulation results show that entrained air contributes to the divergence by successive disturbing on the jet flow. Subjected...
A special feature of the Filament Winding (FW) process is known as pattern: diamond-shaped mosaic that results from the sequence of movements of the mandrel and tow delivery eye. One of the main factors to generate different patterns is the return path of the tow and, for a non-geodesic trajectory, the path depends on the friction between tow and mandrel. Aiming at a practical description of the FW...
The arc welding-based additive manufacturing technology is in its developing state. This technology can be utilized to produce free-form metallic structures for the aerospace and biomedical industry. The current article presents the design of semi-automatic gas tungsten arc welding-based additive manufacturing system for fabricating thin-walled metallic structures. This study aims to analyze the effect...
The proposed work is about the effectiveness of latent heat dispersion on energy storage using phase change materials with modified thermal stratifiers on charging inlet of the tank. A novel flow-governing nozzle with swirl flow injection is designed and fabricated to enhance the steady state of heat flow inside the cascaded thermal energy storage (TES) system. Spherical phase change materials (PCM)...
Improving flexibility, identifying parts and assigning process operations in flexible production are elements that can potentially influence the improvement in the management process. RFID technology has been widely applied in various areas of logistics, supply chain, storage, retail and transport. In flexible production systems, RFID technology is still in the developing phase. The process of applying...
In order to resolve and improve the reverse design of the inner chamber parts, the airflow model of an engine’s cylinder head was taken as research object, and the reverse design methods used for complex inner chamber parts were explored based on slicing method. According to the structural and functional features of airflow model of the cylinder head, the technologies of measure and treatment for...
Fused deposition modelling (FDM) is an additive manufacturing method having the potential to fabricate functional components. As the inherent nature of additive structures, the component stiffness depends on the build parameters such as layer height and raster orientation in addition to the filament material properties. Even on FDM prints with 100% infill density, voids are formed along the interface...
Growth and development of ecosystems are subject to restrictions. Besides exergy, other properties, such as ascendency, have been described as goal functions that can inform about the health of ecosystems and synthesize information about the energy and matter flows in relation to an ideal theoretical state. Ascendency is an index that quantifies both the growth and the degree of organization in an...
The present investigation is focused on the development of a new FSW tool for polymer welding. The newly developed Self-Heated Friction Stir Welding (FSW) tool as well as a conventional FSW tool was employed to join 3-mm polypropylene sheets at different traverse speeds. The spindle torque and various forces exerted on the tool pin during welding were studied. The weldments obtained from both the...
This study presents the application of the spectral line-based weighted-sum-of-gray-gases (SLW) model for the radiative transfer calculation in a participating medium bounded by two infinite, parallel and nongray walls. The proposed methodology presents a simplified approach to calculate the radiative transfer in the medium without the determination of the radiation intensity field at each wavenumber...
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