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This paper suggests a novel nonlinear state-feedback stabilization control law using linear matrix inequalities for a class of time-delayed nonlinear dynamic systems with Lipschitz nonlinearity conditions. Based on the Lyapunov–Krasovskii stability theory, the asymptotic stabilization criterion is derived in the linear matrix inequality form and the coefficients of the nonlinear state-feedback controller...
Aiming to achieve a perfect concept of thinning in hydrodynamic deep drawing assisted by radial pressure (HDDRP), the formability of pure copper thick sheet was investigated. Many process parameters affect the quality of the product during HDDRP. The purpose of the present study is to understand simultaneously the effect of process parameters including maximum fluid pressure, punch velocity, friction...
This paper deals with the heat transfer enhancement due to groove formation in a metallic tube. A detailed computational fluid dynamics (CFD) analysis was performed on helical groove tubes with three geometries (obtained from a published article) to validate the results, and three other geometries, randomly selected, with variable pitch length apart from experiment. The range of Reynolds number was...
Temperature distribution in biological tissue is described by dual-phase lag model supplemented by appropriate boundary and initial conditions. Laser–tissue interactions are taken into account in the source function occurring in this model. The problem is solved using the finite difference method. Next, the Arrhenius integral which is a measure of tissue destruction is calculated. The inverse problem...
The vibration characteristic of a Timoshenko beam resting on nonlinear viscoelastic foundation subjected to any number of spring-mass systems (sprung masses) is governed by system of nonlinear partial differential equations. The governing differential equations are examined using differential quadrature method to be transformed with boundary conditions into a set of algebraic equations. The nonlinear...
The aim of the present paper is to study the effects of rotation and three-phase-lag parameters in a micropolar generalized thermo-viscoelastic medium. By employing normal mode analysis, the analytical expressions for the displacement components, stresses and temperature field are obtained in the physical domain. These expressions are also calculated numerically, and corresponding graphs are plotted...
Appropriate performance of slider-crank mechanisms in cutting machines depends on suitable selection of its parameters. The reaction forces in joints and the internal torque are changed when the crank rotates; therefore, investigating the effects of mechanism parameters on the internal torque and the reaction forces in joints in an operational cycle would be impossible. In this study, an efficient...
Design and analysis of microelectromechanical system based displacement amplification mechanism (MDAM) using analytical and finite element method is presented in this paper. The mechanism consists of side masses, microflexures, and microhinges with one end constrained and the other free. The MDAM acts as a displacement amplification device in a direction perpendicular to the applied displacement direction...
The rotational speed of molds plays a predominant role in defining the quality of cast tubes. The melt during the different rotational speeds strongly influences its motion in forming the final cast tube. Here, an Al–2Si alloy was taken for our experiment and cast at various rotational speeds (600–1200 rpm) to observe the formation of the tubes. The uniform tube was formed at 1000 rpm, the optimum...
Dynamic stability of nonlocal sigmoid functionally graded (S-FGM) nanoplates on elastic medium under bi-axial harmonic loads is studied via four-variable plate theory. A two power-law-based rule of mixture is adopted to describe graded material properties. Hamilton’s principle is employed to derive the governing equations. These equations are expressed in the form of Mathieu–Hill equations and Bolotin’s...
In this work, a ship motion simulator based on a parallel manipulator able to replicate the seakeeping trial is introduced. The mobility of the moving platform is explained through the theory of screws which reveals the existence of three constraint systems reciprocal to the motion-screw system of a central passive kinematic chain. Thereafter, the forward displacement analysis leads to five quadratic...
In this work, the influence of size effect on the primary and the secondary resonance of micro-resonators is investigated. The micro-resonator, which is considered in this study, is a clamped–clamped beam excited by AC and DC electrostatic voltage. The DC voltage is applied to prevent doubling of excitation frequency and tune the range of system’s working frequency. We computed the beam’s motion equation...
In this paper, a novel long-gripping-range compliant flexure-based microgripper is developed for high-precision manipulation of micro-objects. The proposed gripper has simple structure with significant specifications like large amplification factor, no backlash, friction free, parallel motion of jaws, large gripping range and in addition, high-resolution motion in the whole stroke. The actuation of...
At the nanoscale, shear and surface energy play important roles in mechanical behavior of nanostructures, and therefore, such effects should be appropriately considered in the corresponding structural modeling. Herein, surface energy-based Euler–Bernoulli, Timoshenko, and higher-order beam theories are implemented to study buckling of thermally affected tapered nanowires with axial variation of materials...
Many turbo-machines such as turbines and compressors generate axial and radial load during their operation. Conical hydrodynamic journal bearing is proposed to sustain radial load and adjust the effect of axial load on rotating elements. The present study has proposed the performance analysis for conical hydrodynamic journal bearing of semi-cone angles (γ = 5°, 10°, 20°, 30°) for a wide range of radial...
Owing to the attractive front-end styling and restricted available space in the automotive underhood zone, both upstream and downstream directions of heat exchangers are subjected to obstructions in the cooling airflow path. These obstructions disturb the airflow distribution and influence the thermal performance of the heat exchanger. As obstructions are inevitable in the cooling airflow path, a...
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