The Experts below are selected from a list of 108 Experts worldwide ranked by ideXlab platform
Pavle Boškoski - One of the best experts on this subject based on the ideXlab platform.
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Robust Information Indices for Diagnosing Mechanical Drives Under Non-stationary Operating Conditions
Applied Condition Monitoring, 2015Co-Authors: Boštjan Dolenc, Pavle Boškoski, Ðani JuričićAbstract:Reliable fault diagnosis of Mechanical Drives can become nontrivial task in case of restricted instrumentation and variable operating conditions. Under such circumstances changes in the calculated features can not be unambiguously associated with change in system condition. In this paper we propose a feature appropriate for diagnosing faults in Mechanical Drives that is robust to fluctuations in operating conditions. Therefore, its time evolution seems to be correlated only with the machine condition. Instead of relying on spectral properties of the vibration signal, we rather observe changes in the statistical patterns of the derived distribution functions. The effectiveness of the algorithm was evaluated on three datasets comprising both gear and bearing faults under constant and variable load.
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fault detection of Mechanical Drives under variable operating conditions based on wavelet packet renyi entropy signatures
Mechanical Systems and Signal Processing, 2012Co-Authors: Pavle Boškoski, đani JuricicAbstract:In this paper we propose a novel approach for the diagnosis of gearboxes in presumably non-stationary and unknown operating conditions. The approach makes use of information indices based on the Renyi entropy derived from coefficients of the wavelet packet transform of measured vibration records. These indices quantify some statistical properties of instantaneous power of the generated vibration that are largely unaffected by changes in the operating conditions. The analysis is based on probability density of the envelope of a sum of sinusoidal signals with random amplitude and phase. Such an approach requires no a priori information about the operating conditions and no prior data describing physical characteristics of the monitored drive. The fault detection capabilities of the proposed feature set are demonstrated on a two-stage gearbox operating under different rotational speeds and loads with various seeded Mechanical faults.
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Condition prognosis of Mechanical Drives based on nonlinear dynamical models
2010 Conference on Control and Fault-Tolerant Systems (SysTol), 2010Co-Authors: Matej Gašperin, Dani Juricic, Pavle BoškoskiAbstract:Forecasting the condition of the equipment is becoming an important ingredient of the advanced maintenance and asset management systems. In this paper a probabilistic approach to the prognosis of damage progression in gearboxes is presented. It is based on a stochastic nonlinear grey-box model of the underlying wear phenomena. Model parameters are estimated from the available vibration records by using an iterative Maximum Likelihood procedure. The procedure relies on the Expectation-Maximization algorithm and the Unscented Kalman filter for estimation of hidden system states. The algorithm has been used to predict the normal operating horizon of a single-stage gearbox system. Several test runs of the system have been preformed to validate the algorithm.
Eugenio Dragoni - One of the best experts on this subject based on the ideXlab platform.
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Optimal design of radial cylindrical roller bearings for maximum load-carrying capacity
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2013Co-Authors: Eugenio DragoniAbstract:The design of compact and inexpensive Mechanical Drives and gearboxes can take advantage from the use of custom rolling bearings in which the rolling elements are directly in contact with the shaft...
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optimal design of radial cylindrical roller bearings for maximum load carrying capacity
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 2013Co-Authors: Eugenio DragoniAbstract:The design of compact and inexpensive Mechanical Drives and gearboxes can take advantage from the use of custom rolling bearings in which the rolling elements are directly in contact with the shaft and the housing containing them. The custom construction is particularly convenient for the case of roller bearings, either cylindrical or tapered, because these elements are easily manufactured and provide a remarkable loading capacity. Starting from the standard load rating equations available in the literature (ISO standards), this paper develops a step-by-step design procedure for the geometric optimization of radial bearings with cylindrical rollers. The procedure includes constraints on the geometry and leads to the optimal bearing with the maximum static and dynamic load ratings compatible with the space available.
Jr John J Guinan - One of the best experts on this subject based on the ideXlab platform.
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how are inner hair cells stimulated evidence for multiple Mechanical Drives
Hearing Research, 2012Co-Authors: Jr John J GuinanAbstract:Recent studies indicate that the gap over outer hair cells (OHCs) between the reticular lamina (RL) and the tectorial membrane (TM) varies cyclically during low-frequency sounds. Variation in the RL-TM gap produces radial fluid flow in the gap that can drive inner hair cell (IHC) stereocilia. Analysis of RL-TM gap changes reveals three IHC Drives in addition to classic SHEAR. For upward basilar-membrane (BM) motion, IHC stereocilia are deflected in the excitatory direction by SHEAR and OHC-MOTILITY, but in the inhibitory direction by TM-PUSH and CILIA-SLANT. Upward BM motion causes OHC somatic contraction which tilts the RL, compresses the RL-TM gap over IHCs and expands the RL-TM gap over OHCs, thereby producing an outward (away from the IHCs) radial fluid flow which is the OHC-MOTILITY drive. For upward BM motion, the force that moves the TM upward also compresses the RL-TM gap over OHCs causing inward radial flow past IHCs which is the TM-PUSH drive. Motions that produce large tilting of OHC stereocilia squeeze the supra-OHC RL-TM gap and caused inward radial flow past IHCs which is the CILIA-SLANT drive. Combinations of these Drives explain: (1) the reversal at high sound levels of auditory nerve (AN) initial peak (ANIP) responses to clicks, and medial olivocochlear (MOC) inhibition of ANIP responses below, but not above, the ANIP reversal, (2) dips and phase reversals in AN responses to tones in cats and chinchillas, (3) hypersensitivity and phase reversals in tuning-curve tails after OHC ablation, and (4) MOC inhibition of tail-frequency AN responses. The OHC-MOTILITY drive provides another mechanism, in addition to BM motion amplification, that uses active processes to enhance the output of the cochlea. The ability of these IHC Drives to explain previously anomalous data provides strong, although indirect, evidence that these Drives are significant and presents a new view of how the cochlea works at frequencies below 3 kHz.
John W. Muddiman - One of the best experts on this subject based on the ideXlab platform.
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A New High Efficiency Gas Turbine for Mechanical Drives
Volume 3: Coal Biomass and Alternative Fuels; Combustion and Fuels; Oil and Gas Applications; Cycle Innovations, 1998Co-Authors: Jay M. Wilson, J. William Lindenfeld, Kenna D. Vendler, Mike T. Todman, Brian Whinray, John W. MuddimanAbstract:This paper discusses the design and development program that is taking place to enable the availability in mid 1999 of a unit designated the Coberra 6761. This features the aircraft derivative Rolls-Royce RB211-24G upgrade gas generator and a new close coupled Cooper-Bessemer RT61 three stage power turbine. The paper describes the upgrade of the gas turbine from 28.4MW (38 000 SHP) to 31.8MW (42 600 SHP) ISO output power at over 40% thermal efficiency. Measures taken to maximize reliability and maintainability while reducing cost of ownership are described. The improvements in the gas generator compressors and turbines are detailed. The new design features of the power turbine are reviewed including a new support structure, modular service features and 3D orthogonal airfoil designs. The forthcoming validation program for the entire gas turbine unit is also discussed.© 1998 ASME
đani Juricic - One of the best experts on this subject based on the ideXlab platform.
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fault detection of Mechanical Drives under variable operating conditions based on wavelet packet renyi entropy signatures
Mechanical Systems and Signal Processing, 2012Co-Authors: Pavle Boškoski, đani JuricicAbstract:In this paper we propose a novel approach for the diagnosis of gearboxes in presumably non-stationary and unknown operating conditions. The approach makes use of information indices based on the Renyi entropy derived from coefficients of the wavelet packet transform of measured vibration records. These indices quantify some statistical properties of instantaneous power of the generated vibration that are largely unaffected by changes in the operating conditions. The analysis is based on probability density of the envelope of a sum of sinusoidal signals with random amplitude and phase. Such an approach requires no a priori information about the operating conditions and no prior data describing physical characteristics of the monitored drive. The fault detection capabilities of the proposed feature set are demonstrated on a two-stage gearbox operating under different rotational speeds and loads with various seeded Mechanical faults.
