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A Fault Diagnosis Approach for Gears Based on IMF AR Model and SVM  [cached]
Junsheng Cheng,Dejie Yu,Yu Yang
EURASIP Journal on Advances in Signal Processing , 2008, DOI: 10.1155/2008/647135
Abstract: An accurate autoregressive (AR) model can reflect the characteristics of a dynamic system based on which the fault feature of gear vibration signal can be extracted without constructing mathematical model and studying the fault mechanism of gear vibration system, which are experienced by the time-frequency analysis methods. However, AR model can only be applied to stationary signals, while the gear fault vibration signals usually present nonstationary characteristics. Therefore, empirical mode decomposition (EMD), which can decompose the vibration signal into a finite number of intrinsic mode functions (IMFs), is introduced into feature extraction of gear vibration signals as a preprocessor before AR models are generated. On the other hand, by targeting the difficulties of obtaining sufficient fault samples in practice, support vector machine (SVM) is introduced into gear fault pattern recognition. In the proposed method in this paper, firstly, vibration signals are decomposed into a finite number of intrinsic mode functions, then the AR model of each IMF component is established; finally, the corresponding autoregressive parameters and the variance of remnant are regarded as the fault characteristic vectors and used as input parameters of SVM classifier to classify the working condition of gears. The experimental analysis results show that the proposed approach, in which IMF AR model and SVM are combined, can identify working condition of gears with a success rate of 100% even in the case of smaller number of samples.
Acoustic Signal Based Fault Detection in Motorcycles – A Comparative Study of Classifiers  [cached]
Basavaraj S. Anami,Veerappa B. Pagi
International Journal of Image, Graphics and Signal Processing , 2013,
Abstract: The sound patterns generated by the vehicles give a clue of the health conditions. The paper presents the fault detection of motorcycles based on the acoustic signals. Simple temporal and spectral features are used as input to four types of classifiers, namely, dynamic time warping (DTW), artificial neural network (ANN), k-nearest neighbor (k-NN) and support vector machine (SVM), for a suitability study in automatic fault detection. Amongst these classifiers the k-NN is found to be simple and suitable for this work. The overall classification accuracy exhibited by k-NN classifier is over 90%. The work finds applications in automatic surveillance, detection of non-compliance with traffic rules, identification of unlawful mixture of fuel, detection of over-aged vehicles on road, vehicle fault diagnosis and the like.
Implementation of the Six Channel Redundancy to achieve fault tolerance in testing of satellites  [PDF]
H. S. Aravinda,H. D. Maheshappa,Ranjan Moodithaya
Computer Science , 2010,
Abstract: This paper aims to implement the six channel redundancy to achieve fault tolerance in testing of satellites with acoustic spectrum. We mainly focus here on achieving fault tolerance. An immediate application is the microphone data acquisition and to do analysis at the Acoustic Test Facility (ATF) centre, National Aerospace Laboratories. It has an 1100 cubic meter reverberation chamber in which a maximum sound pressure level of 157 dB is generated. The six channel Redundancy software with fault tolerant operation is devised and developed. The data are applied to program written in C language. The program is run using the Code Composer Studio by accepting the inputs. This is tested with the TMS 320C 6727 DSP, Pro Audio Development Kit (PADK).
Gearbox Tooth Cut Fault Diagnostics Using Acoustic Emission and Vibration Sensors — A Comparative Study  [PDF]
Yongzhi Qu,David He,Jae Yoon,Brandon Van Hecke,Eric Bechhoefer,Junda Zhu
Sensors , 2014, DOI: 10.3390/s140101372
Abstract: In recent years, acoustic emission (AE) sensors and AE-based techniques have been developed and tested for gearbox fault diagnosis. In general, AE-based techniques require much higher sampling rates than vibration analysis-based techniques for gearbox fault diagnosis. Therefore, it is questionable whether an AE-based technique would give a better or at least the same performance as the vibration analysis-based techniques using the same sampling rate. To answer the question, this paper presents a comparative study for gearbox tooth damage level diagnostics using AE and vibration measurements, the first known attempt to compare the gearbox fault diagnostic performance of AE- and vibration analysis-based approaches using the same sampling rate. Partial tooth cut faults are seeded in a gearbox test rig and experimentally tested in a laboratory. Results have shown that the AE-based approach has the potential to differentiate gear tooth damage levels in comparison with the vibration-based approach. While vibration signals are easily affected by mechanical resonance, the AE signals show more stable performance.
Gears-Part I  [PDF]
Relly Victoria V. Petrescu, Raffaella Aversa, Bilal Akash, Ronald B. Bucinell, Juan M. Corchado, Filippo Berto, MirMilad Mirsayar, Antonio Apicella and Florian Ion T. Petrescu
American Journal of Engineering and Applied Sciences , 2017, DOI: 10.3844/ajeassp.2017.457.472
Abstract: The gears are today the most widespread and most frequently used mechanical transmissions, all over the world. They must be the factory on an industrial scale, everywhere and have a variety of uses, being extremely important for both the heavy machines of industrial buildings, as well as for domestic appliances, electronics, etc. meet the excessive size normal, big or even huge (used from ships, heavy machines or in energy), but also for the tools watches, or for devices of sizes micro. The work of front wishes to make an overview of the tools and then an introduction to the study of their general and a study customized for gears with fixed. The methods listed for the gears with fixed, can then be customized and used and the gears Planetary Drive (with axis elements). The work of the front and the original components, very much, such as: Geometry, forces, velocities, powers, outputs (gears), which form part of the actual dynamics of the mechanisms and also the most important criterion in respect of the performance of a mechanism.
B. Kamala Soundari,M. Praveena?
International Journal of Computer Science and Mobile Computing , 2013,
Abstract: This paper presents a built-in self-test (BIST)-based scheme for fault diagnosis that can be used toidentify permanent failures and automatic correction in all memories & circuits. The proposed approachoffers a simple test flow and does not require intensive interactions between a BIST controller and a tester.The scheme rests on partitioning of rows and columns of the memory array by employing low cost test logic.It is designed to meet requirements of at-speed test thus enabling detection of timing defects.
Recovery of the sound speed for the Acoustic wave equation from phaseless measurements  [PDF]
Joonas Ilmavirta,Alden Waters
Mathematics , 2015,
Abstract: We recover the higher order terms for the acoustic wave equation from measurements of the modulus of the solution. The recovery of these coefficients is reduced to a question of stability for inverting a Hamiltonian flow transform, not the geodesic X-ray transform encountered in other inverse boundary problems like the determination of conformal factors. We obtain new stability results for the Hamiltonian flow transform, which allow to recover the higher order terms.
Acoustic Emissions from Polymeric Gears  [PDF]
K D Dearn,D Walton
Lecture Notes in Engineering and Computer Science , 2009,
Lubrication Regimes in High-Performance Polymer Spur Gears  [PDF]
K. D. Dearn,T. J. Hoskins,L. Andrei,D. Walton
Advances in Tribology , 2013, DOI: 10.1155/2013/987251
Abstract: Little has been published on the behaviour of polymer gears operating under lubricated conditions. An experimental and analytical programme was undertaken to classify the regimes of EHL under which polymer spur gears operate. In doing so theoretical film thicknesses were calculated and then used to classify the regime according to Johnson's Map. The effects of lubrication on the operating efficiencies of high-performance polymer gears were interpreted and from these results coefficients of friction were derived. In addition to this the effect of tooth geometry was investigated and the beneficial influence of high-pressure angle tooth geometry is demonstrated. At loads typically associated with polymer gears the operating regime is shown to be mixed film lubrication. When high-pressure angle gears were tested at high loads the operating regime became full film lubrication and relatively little tooth flank damage occurred. 1. Introduction Polymer gears are frequently employed in situations where no external lubrication is permitted, such as in food processing machines and in office equipment, such as printers. Unlubricated (dry) polymer gears are limited in both load and speed due to high frictional forces. This creates high temperatures leading to rapid wear and even melting. Developments in polymer materials (e.g., polymers containing glass fibres and an internal lubricant such as PTFE) and gear tooth geometries have moved polymer gears from motion to power transmitters [1, 2]. In many of these applications an external lubricant such as grease is permitted. Very few examples of oil or water lubricated polymer gear applications exist. External lubricants can reduce the friction, compared to dry running gears and the lubricant can also act as a coolant. Polymer gears operating under external lubrication permit much higher loads and speeds and offer the possibility of new design solutions to a number of applications traditionally reserved for steel gears. The reduction of frictional losses in steel gears has been studied by various authors [3, 4]. However, these results are not directly applicable to polymer gear testing. The low modulus of polymer gears makes them resilient when the teeth come into contact. This deformation results in a change in the curvature of the gear tooth, increasing the contact area during tooth contact. Little has been published on externally lubricated polymer gears, the exception being Song et al. [5] who looked at polymer/steel combinations only and compared oil thicknesses and pressures with steel/steel pairs. They reported
STARE velocity at large flow angles: is it related to the ion acoustic speed?
M. V. Uspensky, A. V. Koustov,S. Nozawa
Annales Geophysicae (ANGEO) , 2006,
Abstract: The electron drift and ion-acoustic speed in the E region inferred from EISCAT measurements are compared with concurrent STARE radar velocity data to investigate a recent hypothesis by Bahcivan et al. (2005), that the electrojet irregularity velocity at large flow angles is simply the product of the ion-acoustic speed and the cosine of an angle between the electron flow and the irregularity propagation direction. About 3000 measurements for flow angles of 50°–70° and electron drifts of 400–1500 m/s are considered. It is shown that the correlation coefficient and the slope of the best linear fit line between the predicted STARE velocity (based solely on EISCAT data and the hypothesis of Bahcivan et al. (2005)) and the measured one are both of the order of ~0.4. Velocity predictions are somewhat better if one assumes that the irregularity phase velocity is the line-of-sight component of the E×B drift scaled down by a factor ~0.6 due to off-orthogonality of irregularity propagation (nonzero effective aspect angles of STARE observations).
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