Search results for "frequency [modulation]"
showing 10 items of 569 documents
Vibration signature analysis for rotor broken bar diagnosis in double cage induction motor drives
2013
The paper investigates the diagnosis of rotor broken bars in field oriented controlled (FOC) double cage induction motor drives, using current and vibration signature analysis techniques. The Impact of the closed loop control system cannot be neglected when the detection of asymmetries in the machine are based on the signature analysis of electrical variables. The proposed diagnosis approach is based on optimized use of wavelet analysis by a pre-processing of phase current or axial/radial vibration signals. Thus, the time evolution of the tracked rotor fault components can be effectively analyzed. This paper shows also the relevance of the fault components computed from axial vibration sign…
A Wireless Acoustic Array System for Binaural Loudness Evaluation in Cities
2017
Networks of acoustic sensors are being deployed in smart cities to continuously monitor noise levels. In this paper, a novel acoustic sensor device is designed for binaural loudness evaluation, in a standalone platform. The audio is acquired from an array of microphones and a binaural signal is synthesized by a direction-of-arrival algorithm and a head-related transfer function. Hardware setup and software algorithms are presented and the results are discussed. Finally, the tests conducted in an early deployment show the feasibility of using the device to carry out large temporal and spatial sampling for the evaluation of binaural loudness.
On the Impact of Plant Model and Controller Sophistication on Performance of Disturbance Attenuation and System Robustness
2006
In the paper the problem of disturbance attenuation performance in single-loop control system is investigated. Modified MV control strategy with bounded control variance is used as benchmark for both LQG and classically and optimally tuned PID-type controllers. Certain time and frequency domain functions are then examined to further assess the control performance in terms of robustness. It has been shown that as long as the system to be controlled is delay-free, and there is no extreme demand on performance, simple lag-delay system model along with optimally tuned PID control algorithm provides control quality similar to that of LQG controlled original system assuming the same bound on cont…
Implementation of the ERI standard and Evaluation of Applications with several low-cost technologies
2008
The electronic registration and identification (ERI) systems allow carrying out a remote, secure and univocal identification of a vehicle through electronic devices. This paper presents the implementation of the ERI standard (ISO 24534 & 24535) in an API to develop applications. The implementation took into account the different components of the system to build the architecture of the identification system. Several applications have been developed in order to test this API with several low-cost technologies (Wifi, Bluetooth and RFID).
Fatigue life prediction under wide band random loading
2004
In this paper, a method for the high-cycle fatigue life prediction of components subjected to gaussian, stationary, wide band random loading is presented. It allows the user to evaluate the fatigue life of components subjected to uniaxial stress states directly from the stress power spectral density (PSD), avoiding onerous simulations in time domain. The proposed method can be applied to random stress processes having PSD of any shape, and the fatigue life predictions obtained are more accurate than that provided by most of the frequency domain techniques proposed in literature.
Fatigue life calculation by means of the cycle counting and spectral methods under multiaxial random loading
2005
The paper contains a new algorithm for estimation of fatigue life in HCF regime under multiaxial random loading using spectral methods. Loading of Gaussian distribution and narrow- and broad-band frequency spectra were assumed. Various characteristic states of multiaxial loading were considered. The equivalent stress history was determined with use of the failure criteria of multiaxial fatigue based on the critical plane. For determination of the critical plane position, the method of variance was applied. During simulation, the authors compared the results obtained by a spectral method in the frequency domain with those from the rain-flow algorithm in the time domain. The paper also contai…
Green Data Centres providing ancillary services to power grid
2015
This work investigates the possibility for a Data Centre to provide services to the Grid. In particular, the paper simulates a sudden shift of frequency because of a power decrease and estimates how a real-life Data Centre can contribute the secondary frequency regulation.
EEMD based analysis of vehicle crash responses
2015
The vehicle crash is a complex process with nonlinear large deformation of structures. The analysis of the crash process is one of the challenges for all vehicle safety researchers. In this paper, the Ensemble Empirical Mode Decomposition (EEMD) method is applied in the analysis of crash responses in order to achieve some meaningful results. With the help of EEMD, the crash responses are decomposed into a trend signal and some high frequency fluctuations. By studying the load path of vehicle design, each component is corresponding to the structure of vehicle body. Consequently, some parameters of vehicle crash model can be identified. A frontal crash of Toyota Yaris is employed for demonstr…
Bearing fault detection for drivetrains using adaptive filters based wavelet transform
2017
Predicting a localized defect on a rolling bearing during the degradation process before a complete failure is crucial to prevent system failures, unscheduled downtimes and substantial loss of productivity. During this process, impulses associated with the fault are weak, nonstationary or time-frequency varying, and contaminated by noises, which render the problem of extracting these impulses very difficult. This work investigates the effectiveness of common signal processing techniques on predicting incipient faults, e.g. Fast Fourier transform, Short-Time Fourier transform, Wavelet transform. It was found that an adaptive filter is required to enhance and reconstruct the signals during th…
Hammerstein Model-Based Robust Control of DC/DC Converters
2007
This paper deals with model-based robust control of DC/DC power electronic converters. The converter is modelled by means of its static characteristic and a few continuous-time linear and time-invariant (LTI) models corresponding to contiguous ranges of duty-cycle. The model appears as a Hammerstein model in which the values of the parameters of the LTI part depend on the actual duty-cycle operating range. This suggests to describe the converter as an uncertain system to be controlled using robust control techniques. Frequency domain approach is used for describing the nominal model and the uncertainty. In view of applying robust control, identification of the LTI models is performed by mea…