Similarity assessment between 3D models is an important problem in many fields including medicine, biology and industry. As there is no direct method to compare 3D geometries, different model representations (shape signatures) are developed to enable shape description, indexing and clustering. Even though some of those descriptors proved to achieve high classification precision, their application is often limited. In this work, a different approach to similarity assessment of 3D CAD models was presented. Instead of focusing on one specific shape signature, 45 easy-to-extract shape signatures were considered simultaneously. The vector of those features constituted an input for 3 machine learning algorithms: the random forest classifier, the support vector classifier and the fully connected neural network. The usefulness of the proposed approach was evaluated with a dataset consisting of over 1600 CAD models belonging to 9 separate classes. Different values of hyperparameters, as well as neural network configurations, were considered. Retrieval accuracy exceeding 99% was achieved on the test dataset.
Automation of earth moving machineries is a widely studied problem. This paper focusses on one of the main challenges in automation of the earth moving industry, estimation of loading torque acting on the machinery. Loading torque acting on the excavation machinery is a very significant aspect in terms of both machine and operator safety. In this study, a disturbance observer-assisted control system for the estimation of loading torque acting on a robotic backhoe during excavation process is presented. The proposed observer does not use any acceleration measurements, rather, is proposed as a function of joint velocity. Numerical simulations are performed to demonstrate the effectiveness of the proposed control scheme in tracking the reaction torques for a given dig cycle. Co-simulation experiments demonstrate robust performance and accurate tracking of the proposed control in both disturbance torque and position tracking. Further, the performance and sensitivity of the proposed control are also analyzed through the help of performance error quantifiers, the root-mean-square (RMS) values of the position and disturbance tracking errors.
A brief review of the existing autonomous underwater vehicles, their types, design, movement abilities and missions is presented. It is shown, the shape optimization design and enhancement of their efficiency is the main problem for further development of multipurpose glider technologies. A comparative study of aerodynamic performance of three different shape designs (the airfoil NACA0022 based (I), flattened ellipsoidal (II) and cigar-type (III) bodies of the same volumes) has been carried out. Geometrical modelling, meshing and computational fluid dynamics (CFD) simulations have been carried out with AnSys15.0. The pathlines and wall shear stress distributions have been computed to understand the advantages and disadvantages of each shape. The lift and drag coefficients, aerodynamic quality, power index and pitching moment have been computed. The higher efficiency of the shape I/shape II at higher/lower angles of attack (> 20o and < 20o) has been found. The shape III develops high speeds at the same angles of attack and has higher manoeuvrability at relatively low aerodynamic quality. The comparative analysis of the flow capabilities of studied autonomous undersea vehicles proposes some design improvement for increasing their energy efficiency and flow stability.
The paper presents a simulation model of the hybrid magnetic bearing dedicated to simulations of transient state. The proposed field-circuit model is composed of two components. The first part constitutes a set of ordinary differential equations that describes electrical circuits and mechanics. The second part of the simulation model consists of parameters such as magnetic forces, dynamic inductances and velocity-induced voltages obtained from the 3D finite element analysis. The MATLAB/Simulnik softwarewas used to implement the simulation model with the required control system. The proposed field-circuit model was validated by comparison of time responses with the prototype of the hybrid magnetic bearing.
An attempt is made in the current research to obtain the fundamental buckling torque and the associated buckled shape of an annular plate. The plate is subjected to a torque on its outer edge. An isotropic homogeneous plate is considered. The governing equations of the plate in polar coordinates are established with the aid of the Mindlin plate theory. Deformations and stresses of the plate prior to buckling are determined using the axisymmetric flatness conditions. Small perturbations are then applied to construct the linearised stability equations which govern the onset of buckling. To solve the highly coupled equations in terms of displacements and rotations, periodic auxiliary functions and the generalised differential quadrature method are applied. The coupled linear algebraic equations are a set of homogeneous equations dealing with the buckling state of the plate subjected to a unique torque. Benchmark results are given in tabular presentations for combinations of free, simply-supported, and clamped types of boundary conditions. It is shown that the critical buckling torque and its associated shape highly depend upon the combination of boundary conditions, radius ratio, and the thickness ratio.
In the present work, a procedure for the estimation of internal damping in a cracked rotor system is described. The internal (or rotating) damping is one of the important rotor system parameters and it contributes to the instability of the system above its critical speed. A rotor with a crack during fatigue loading has rubbing action between the two crack faces, which contributes to the internal damping. Hence, internal damping estimation also can be an indicator of the presence of a crack. A cracked rotor system with an offset disc, which incorporates the rotary and translatory of inertia and gyroscopic effect of the disc is considered. The transverse crack is modeled based on the switching crack assumption, which gives multiple harmonics excitation to the rotor system. Moreover, due to the crack asymmetry, the multiple harmonic excitations leads to the forward and backward whirls in the rotor orbit. Based on equations of motions derived in the frequency domain (full spectrum), an estimation procedure is evolved to identify the internal and external damping, the additive crack stiffness and unbalance in the rotor system. Numerically, the identification procedure is tested using noisy responses and bias errors in system parameters.
Contemporary research on mobile robotics aims at designing robots that will be able to traverse an extremely varied environment. One of the most universal modes of locomotion is the serpentine movement. A majority of modern snake-like robots use electric drives. This study presents a snake-like robot made out of McKibben muscles. Using a pneumatic cable with muscles arranged in series, it is possible to create a robot of any length, limited only by the length of the muscle cables. Because the control system and the body of the robot are separate, the robot can be used for rescue missions involving high risk of explosion of flammable substances and for missions taking place on extremely difficult terrain.
Editor-in-Chief
Prof. Marek Wojtyra, Warsaw University of Technology, Poland
Editorial Board
Prof. Krzysztof Arczewski, Warsaw University of Technology, Poland
Prof. Janusz T. Cieśliński, Gdańsk University of Technology, Poland
Prof. Antonio Delgado, LSTM University of Erlangen-Nuremberg, Germany
Prof. Peter Eberhard, University of Stuttgart, Germany
Prof. Jerzy Maciej Floryan, The University of Western Ontario, Canada
Prof. Janusz Frączek, Warsaw University of Technology, Poland
Prof. Zbigniew Kowalewski, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland
Prof. Zenon Mróz, Institute of Fundamental Technological Research, Polish Academy of Sciences, Poland
Prof. Andrzej J. Nowak, Silesian University of Technology, Poland
Dr. Andrzej F. Nowakowski, The University of Sheffield, United Kingdom
Prof. Jerzy Sąsiadek, Carleton University, Canada
Prof. Jacek Szumbarski, Warsaw University of Technology, Poland
Prof. Tomasz Wiśniewski, Warsaw University of Technology, Poland
Prof. Günter Wozniak, Chemnitz University of Technology, Germany
Assistant to the Editor
Małgorzata Broszkiewicz, Warsaw University of Technology, Poland
Editorial Advisory Board
Prof. Alberto Carpinteri, Politecnico di Torino, Italy
Prof. Fernand Ellyin, University of Alberta, Canada
Prof. Feng Gao, Shanghai Jiao Tong University, P.R. China
Prof. Emmanuel E. Gdoutos, Democritus University of Thrace, Greece
Prof. Gregory Glinka, University of Waterloo, Ontario, Canada
Prof. Andrius Marcinkevicius, Vilnius Gedeminas Technical University, Lithuania
Prof. Manuel José Moreira De Freitas, Instituto Superior Tecnico, Portugal
Prof. Andrzej Neimitz, Kielce University of Technology, Poland
Prof. Thierry Palin-Luc, Arts et Métiers ParisTech, Institut Carnot Arts, France
Prof. Andre Pineau, Centre des Matériaux, Ecole des Mines de Paris, France
Prof. Narayanaswami Ranganathan, LMR, Ecole Polytechnique de l'Université de Tours, France
Prof. Jan Ryś, Cracow University of Technology, Poland
Prof. Adelia Sequeira, Technical University of Lisbon, Portugal,
Prof. Józef Szala, University of Technology and Life Sciences in Bydgoszcz, Poland
Prof. Edmund Wittbrodt, Gdańsk University of Technology, Poland
Prof. Jens Wittenburg, Karlsruhe Institute of Technology, Germany
Prof. Stanisław Wojciech, University of Bielsko-Biała, Poland
Language Editor
Lech Śliwa, Institute of Physiology and Pathology of Hearing, Warsaw, Poland
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About the Journal
Archive of Mechanical
Engineering is an international journal publishing works of wide
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engineering. The journal is peer-reviewed and is published both in
electronic and printed form. Archive of Mechanical Engineering
publishes original papers which have not been previously published in
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