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Metamaterials are artificial composite materials engineered to have properties that may not be found in nature. By exploring locally resonant effect of the building units, elastic metamaterials are able to possess negative values of effective mass, effective bulk or shear modulus. Mass-spring and continuum material versions of these elastic metamaterials are reported and the physical mechanisms of...
In this paper we analyze the optimal control problem for a class of affine nonlinear systems under the assumption that the associated Lie algebra is nilpotent. The Lie brackets generated by the vector fields which define the nonlinear system represent a remarkable mathematical instrument for the control of affine systems. We determine the optimal control which corresponds to the nilpotent operator...
Vibrations of offset printing presses are serious problem, which cause many difficulties while printing and impair quality of the prints. The biggest problem lies in construction of printing unit. It mainly consists of three cylinders, but two of them are in a direct contact generate undesired vibrations. Construction of the cylinders makes that stiffness of the unit varies periodically while printing...
For detailed study of complex chemical reactions mechanisms experiment is conducted for selected private reactions. This causes a problem of kinetic parameters getting—the same set of rate constants must describe both public and private reaction stages, and also a general mechanism. In this paper, solution of this problem for a reaction of olefins hydroalumination is proposed. To optimize the computational...
Middle ear surgery techniques have enabled to improve hearing destroyed by a disease. Despite huge improvement in instrumentation and techniques the results of hearing improvement surgery are still difficult to predict. This paper presents the results of vibrations measurements in a human middle ear obtained at the Medical University of Lublin. Vibrations of the stapes in the case of the intact ossicular...
The analysis and design of the extended state observer (ESO) involves a continuous non-smooth structure, thus the study of the ESO dynamic requires mathematical tools of the nonlinear systems analysis. This paper establishes the sufficient conditions for absolute stability of the ESO. Based on this study, a methodology to estimate several nonlinear functions in dynamics systems is proposed.
The dynamics of classical robotic systems are usually described by ordinary differential equations via selecting a minimum set of independent generalized coordinates. However, different parameterizations and the use of a nonminimum set of (dependent) generalized coordinates can be advantageous in such cases when the modeled device contains closed kinematic loops and/or it has a complex structure....
The paper presents an active control system that counteracts the development of chatter vibration. The vibration amplitude depends on the dynamic properties of the machine tool, cutting tool and work-piece. In the paper we analyze the case when the loss of machining stability is caused by the work-piece. The proposed active control system employs electromagnet or piezoelectric actuator to suppress...
The vehicles with high gravity centre are more prone to roll over. The paper deals with a method of dynamics analysis of fire engines which is an example of these types of vehicle. Algorithms for generating the equations of motion have been formulated by homogenous transformations and Lagrange's equation. The model presented in this article consists of a system of rigid bodies connected one with another...
In this paper a three degrees of freedom autoparametric system with limited power supply is investigated numerically. The system consists of the body, which is hung on a spring and a damper, and two pendulums connected by shape memory alloy (SMA) spring. Shape memory alloys have ability to change their material properties with temperature. A polynomial constitutive model is assumed to describe the...
The paper approaches the problem of the command functions of galvanometer-based scanners (GS) that are necessary to produce the linear plus parabolic scanning function of the GS, which we have proved previously to produce the highest possible duty cycle (i.e., time efficiency) of the device. We have completed this theoretical aspect (which contradicted what has been stated previously in the literature,...
Long waves generated by a moving atmospheric pressure distribution, associated with a storm, in coastal region are investigated numerically. For simplicity the moving atmospheric pressure is assumed to be moving only in the alongshore direction and the beach slope is assumed to be a constant in the on-offshore direction. By solving the linear shallow water equations we obtain numerical solutions for...
An analytical study of the two degrees of freedom nonlinear dynamical system is presented. The internal motion of the system is separated and described by one fourth order differential equation. An approximate approach allows reducing the problem to the Duffing equation with adequate initial conditions. A novel idea for an effective study of nonlinear dynamical systems consisting in a concept of the...
We examine an energy harvesting system of two magnetopiezoelastic oscillators coupled by electric circuit and driven by harmonic excitation. We focus on the effects of synchronization and escape from a single potential well. In the system with relative mistuning in the stiffness of the harvesting oscillators, we show the dependence of the voltage output for different excitation frequencies.
This paper presents the problem of control of anti-aircraft missile launcher mounted on a moving carrier-vehicle. Direct excitations on the vehicle from the road cause adverse vibrations of the launcher. In order to increase the precision of the guiding system in the conditions of self-propelled movement of the setup on a bumpy road, the adaptive control algorithm was proposed. Some research results...
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