in this study, friction stir spot welding (fssw) is applied to join the tial6v4 titanium alloy with 1.5 mm thickness and then the effect of rotational speed and tool dwell time on microstructure and mechanical properties is investigated. in this regard, the speed of the tool rotation was considered as 800, 1000, and 1200 rpm, as well as the tool dwell time was set at 7 and 12s. microstructural ...

Rotablation (rotational atherectomy) is an acknowledged method of percutaneous treatment of highly calcified coronary artery lesions that cannot be treated with traditional angioplasty. The complexity of the technique and usage of very specific equipment can contribute to the development of uncommon complications. We present a case of percutaneous retrieval of a damaged rotational atherectomy b...

A triangular mixed finite element model for the elasto-plastic analysis of Kirchhoff plates is presented. The proposed discretization is based on rigid in bending elements connected by means of rotational springs between the inter-element sides and constant bending moments on the influence area of each node. The continuity of the normal bending moment through the sides allows a standard Helling...

Treating tumors that are subject to intrafractional motion (e.g. lung tumors) with scanned particle beams leads to deterioration of the deposited dose distributions. One possible technique to mitigate motion effects is beam tracking [1]. In case of rotational motion the beam path and thereby the dose deposition in the plateau region proximal of the Bragg peak position changes despite adaptation...

This paper presents a nonlinear robust control strategy to solve the path tracking problem for a quadrotor unmanned aerial vehicle. The helicopter motion equations is obtained by the LagrangeEuler formalism. The control structure is performed through a nonlinear H∞ controller to stabilize the rotational movements and a control law based on backstepping approach to track the reference trajectory...

In this paper, a family of weighted neighborhood sequence distance functions defined on the square grid is presented. With this distance function, the allowed weight between any two adjacent pixels along a path is given by a weight sequence. We build on our previous results, where only two or three unique weights are considered, and present a framework that allows any number of weights. We show...

Restoration of esthetics is an important factor to consider in the fabrication of a removable partial denture (RPD) . 1 Several types of polymers and metal alloys have been used in RPD construction. Frequently, RPD clasps made from the same alloy as the metal framework. The most common alloys used for clasps are cobalt-chromium (Co-Cr) alloy and gold and titanium alloys, although these may be u...

Abstract: This paper presents a predictive and nonlinear robust control strategy to solve the path tracking problem for a quadrotor helicopter. The dynamic motion equations are obtained by the Lagrange-Euler formalism. The control structure is performed through a model-based predictive controller (MPC) to track the reference trajectory and a nonlinear H∞ controller to stabilize the rotational m...

In this paper we present a PID+ solution to the problem of relative translational and rotational tracking, using the concept of integrator backstepping. By using an integrator augmentation technique, we include integral effect in the controller to account for the unknown orbital perturbations. The controller solution utilizes the quaternion representation to achieve a shorter rotation path on c...