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Mihaela M.A.,Polytechnic University of Bucharest | Gheorghe G.I.,The National Institute of Research | Luigi G.,Polytechnic University of Turin | Daniel C.C.,Polytechnic University of Bucharest | Octavian D.G.,Polytechnic University of Bucharest
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2013

In this paper are presented the theoretical aspects and the mathematical relationships which describe how can be obtained and make a control of the mechanical transmissibility of a m/k/c system by replacing the mechanical dynamic absorber with an electro-mechanical system, consisting of an electrodynamic actuator and an external electric circuit The technical solution is evaluated in terms of effectiveness and efficiency of the control of system mechanical transmissibility. Also, are presented concisely some solutions to control the mechanical transmissibility, indicating the limitations and difficulties in their practical application. In the paper is presented a mathematical model of a simple m/k/c with 1 DOF system, consisting of a system of equations describing the dynamics of the system under the conditions in which on the object with mass m to be isolated from external vibration action operate one disturbing external force. The system of equations is useful in the study of dynamic behaviour and mechanical transmissibility of the system and also for the design of the modalities of control of parameters which have a major influence on the behavior of the system. From the analysis of technical solutions that can be applied to control the mechanical transmissibility of the m/k/c with 1 DOF system (the change of mechanical parameters of constituent elements of the system or the use of a purely mechanical dynamic absorber) it follows that they are complicated and difficult to apply in practice. The classical solutions ensure a reliable operation of the system only in very tight limits of dynamic conditions, which is not convenient for situations in which the system is running out of the limits set by design or when transitional regimes represent a significant percentage. The solution of replacing the purely mechanical dynamic absorber or to change the parameters of mechanical elements of the structure of the m/k/c with 1 DOF system with a electrodynamic actuator which is connected at the terminals an external electric circuit composed of resistors, capacitors and inductors of different values, provide a better flexibility in choosing the control parameters and their values in order to establish and control the mechanical transmissibility of the system. A part of the article shows the way in which the introduction of the electrodynamic actuator and his external electrical circuit is similar with the action of the mechanical dynamic absorber. Also are highlighted the similarities in effects on the mechanical transmissibility of the system between the action of a dynamic mechanical absorber (consisting of an additional mass ma, a spring ka and a viscous damper ca) and the influence of the external electric circuit (electrical resistance, capacitor and inductance). The mathematical relations presented in the paper shows that the replacement of mechanical dynamic absorber with an electrodynamic actuator connected with an external electric circuit is a solution that allows the control of the mechanical transmissibility of the m/k/c system, the system acquiring a flexibility specific for the electrical applications, with the ability to change fast and efficient the mechanical transmissibility of the system. The electrodynamic actuator and his external electric circuit, in this particular application, acts like a bidirectional converter of the mechanical energy into electrical energy and vice versa, adjustable within certain limits. The electrodynamic actuator and the electrical components of the external circuit can be considered a way of passive control (constant parameters), a semi-active control (parameters adapted in steps) or active control (continuously variable parameters, adjusted at the operational conditions) to control the mechanical transmissibility of the m/k/c basic system. The results and conclusions presented in this paper allow in depth study, both theoretical and practical, of the technical solution of the introduction in the structure of an m/k/c system of an electrodynamic actuator and his specific electro-mechanical components and electrical control, in order to control the mechanical transmissibility of a certain system. © 2013, Editura Cefin. All rights reserved. Source


Prodan M.,Ovidius University | Stanescu I.,Ovidius University | Ciupina V.,Ovidius University | Gheorghiu D.,The National Institute of Research | And 2 more authors.
Romanian Biotechnological Letters | Year: 2010

Nanostructured carbon thin film has a large application in different working area. These work will present nanostructured carbon thin films obtained by TVA (Thermionic Vacuum Arc) method, with nanometric size (thickness < 100nm). The most important feature of these films is hardness given by sp2-sp3 ratio of films composition. Titan alloy are used frequently in biomedical application due to highly biocompatibility. The resulted prosthetic from these coated alloy, with high hardness carbon films, lead on substantial improvement quality, from mechanical point of view with about 100% related to other protection methods. TVA method allows a morphological smoothly DLC (diamond like carbon) type carbon films to obtain. The resulted DLC is thicker and has diamond properties, like: high hardness (3000-5000kg/mm2), small friction coefficient (0,1-0,2), chemical inactive, abrasion hardness (1,6x10,9mm3/mN) and also electrical properties. Obtained films were studied by electron microscopy techniques (TEM, SEM, HRTEM, EELS, SAED and PED). PED (Precession of Electron Diffraction) method is recently developed and substantially improves the crystalline structure studies by means of electron diffraction patterns acquisition very close to kinematical condition. Also, the mechanical resistance was tested and compared for coated and uncoated alloys. The geometry of used sample is cylindrical with 100 mm length and 3 mm diameter. Dynamic tensile and bend tests were performed using method described by the SR EN 10002-1:2002 standard. Dynamic tensile test show increasing of sample length from 4 mm (uncoated sample) to approximately 6 mm for coated sample, and the maximum stress and bending momentum values gives that carbon coated samples are more elastic. © 2010 University of Bucharest. Source


Boeriu P.,IHE UNESCO Delft | Moldovanu A.,The National Institute of Research | Vaduva V.,The National Institute of Research
Romanian Review Precision Mechanics, Optics and Mechatronics | Year: 2012

Sediments of the sand particle dimension or bigger will deposit in a shorten time after the entry of the flow in the lake. Delta deposits are formed when the flow enters the lake and coarse materials are deposited and the speed and carrying capacity diminishes. Amount of sediment in a reservoir should be evaluated periodically, in this sense developing in the INCDMecatronica & Measurement Technique, a family of intelligent high-tech equipment used to monitor sediment, including the purchase of specific software, storage, processing and transmitting data. Source

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