Measurement Science Research Papers - Academia.edu (original) (raw)
This review presents possible strategies to increase the operational frequency range of vibration-based micro-generators. Most vibration-based micro-generators are spring-mass-damper systems which generate maximum power when the resonant... more
This review presents possible strategies to increase the operational frequency range of vibration-based micro-generators. Most vibration-based micro-generators are spring-mass-damper systems which generate maximum power when the resonant frequency of the generator matches the frequency of the ambient vibration. Any difference between these two frequencies can result in a significant decrease in generated power. This is a fundamental limitation of resonant vibration generators which restricts their capability in real applications. Possible solutions include the periodic tuning of the resonant frequency of the generator so that it matches the frequency of the ambient vibration at all times or widening the bandwidth of the generator. Periodic tuning can be achieved using mechanical or electrical methods. Bandwidth widening can be achieved using a generator array, a mechanical stopper, nonlinear (e.g. magnetic) springs or bi-stable structures. Tuning methods can be classified into intermittent tuning (power is consumed periodically to tune the device) and continuous tuning (the tuning mechanism is continuously powered). This review presents a comprehensive review of the principles and operating strategies for increasing the operating frequency range of vibration-based micro-generators presented in the literature to date. The advantages and disadvantages of each strategy are evaluated and conclusions are drawn regarding the relevant merits of each approach.
- by Wieslaw Staszewski and +1
- •
- Engineering, Mechanical Engineering, Lamb wave, Crack detection
A whole-field three-dimensional (3D) particle tracking velocimetry (PTV) tool for diagnostics in fluid mechanics is presented. Specifically, it is demonstrated why and when PTV is the natural choice in 3D applications compared to particle... more
A whole-field three-dimensional (3D) particle tracking velocimetry (PTV) tool for diagnostics in fluid mechanics is presented. Specifically, it is demonstrated why and when PTV is the natural choice in 3D applications compared to particle image velocimetry (PIV). Three different tracking methods are investigated, namely the nearest neighbour, the neural network and the relaxation method. In order to demonstrate the use of PTV for 3D applications, the selected tracking schemes are implemented for use with the defocusing digital particle image velocimetry (DDPIV) technique. The performance of the tracking algorithms is evaluated based on synthetic 3D information. Furthermore, the potential benefit of a merging between the PIV and PTV approaches is explored within the DDPIV framework. The results show that the relaxation tracking method is the most robust and efficient, while the combined PIV/PTV analysis brings significant improvements solely with the neural network scheme. In terms of errors, PTV is found to be more sensitive to particle reconstruction errors than the DDPIV cross-correlation analysis.
The last two decades have shown an increasing trend in the use of navigation technologies in several applications including land vehicles and automated car navigation. Navigation systems incorporate the global positioning system (GPS) and... more
The last two decades have shown an increasing trend in the use of navigation technologies in several applications including land vehicles and automated car navigation. Navigation systems incorporate the global positioning system (GPS) and the inertial navigation system (INS). While GPS provides position information when there is direct line of sight to four or more satellites, INS utilizes the local measurements of angular velocity and linear acceleration to determine both the vehicle's position and attitude. Both systems are integrated together to provide reliable navigation solutions by overcoming each of their respective shortcomings. The present integration schemes, which are predominantly based on Kalman filtering, have several inadequacies related to sensor error models, immunity to noise and observability. This paper aims at introducing a multi-sensor system integration approach for fusing data from an INS and GPS hardware utilizing wavelet multi-resolution analysis (WMRA) and artificial neural networks (ANN). The WMRA is used to compare the INS and GPS position outputs at different resolution levels. The ANN module is then trained to predict the INS position errors in real time and provide accurate positioning of the moving vehicle. The field-test results have demonstrated that substantial improvements in INS/GPS positioning accuracy could be obtained by applying the proposed neuro-wavelet technique.
Arrays of in-fibre Bragg gratings (IFBGs) are increasingly being employed to measure strain in a variety of structures. To maximize the number of IFBGs that can be multiplexed from a broad band source requires accurate control and... more
Arrays of in-fibre Bragg gratings (IFBGs) are increasingly being employed to measure strain in a variety of structures. To maximize the number of IFBGs that can be multiplexed from a broad band source requires accurate control and reproducibility of the Bragg centre wavelength. In this communication we demonstrate that the combination of a phase mask based interferometer and tuneable UV writing wavelength can provide high resolution control over the Bragg centre wavelength. The interferometer is shown to have two regimes of operation, offering a high resolution (0.03 nm) or a large spectral range (51 nm). The technique is compared to previous writing methods and is demonstrated experimentally.
In the paper the set of representative parameters for a comprehensive assessment of the surface texture status after slide burnishing has been proposed. The analysis of correlations between the parameters of the surface texture, obtained... more
In the paper the set of representative parameters for a comprehensive assessment of the surface texture status after slide burnishing has been proposed. The analysis of correlations between the parameters of the surface texture, obtained by slide diamond burnishing of 317Ti steel has been performed. Correlations have been determined and several groups of surface texture parameters with strong mutual correlations (also parameters uncorrelated with the other) have been selected. For both groups of parameters - representative and uncorrelated - experimental mathematical relations defining influences of the input parameters of slide diamond burnishing on the surface texture parameters have been developed. Also, interaction effects for individual parameters of this finishing process have been disclosed. It has been found that by appropriate selection of input conditions of the slide diamond burnishing process, it is possible to obtain a wide range of states of the surface texture.
Porous silicon (PS) is defined as a composition of a silicon skeleton permeated by a network of pores or in other word, PS is a network of silicon nanowires and nanoholes which are formed when the crystalline silicon wafers are etched... more
Porous silicon (PS) is defined as a composition of a silicon skeleton permeated by a network of pores or in other word, PS is a network of silicon nanowires and nanoholes which are formed when the crystalline silicon wafers are etched electrochemically in electrolyte solution such as hydrofluoric (HF) acid . PS shows different features in comparison to the bulk silicon such as shifting of fundamental absorption edge into the short wavelength and photoluminescence visible region. The PS material possesses interesting characteristics such as larger surface to volume ratio, high-intensity of nano porous structure and low refractive index. This paper presents the synthesis and characterization of electrochemically anodized PS structures. The effect of short anodization time on the PS structures is investigated. The PS surface morphology and optical properties are characterized using scanning electron microscopy (SEM) and photoluminescence (PL) spectrometer, respectively.
In this paper, the selected results of measurements and analysis of the active surfaces of a new generation of coated abrasive tools obtained by the use of focus-variation microscopy (FVM) are presented and discussed. The origin of this... more
In this paper, the selected results of measurements and analysis of the active surfaces of a new generation of coated abrasive tools obtained by the use of focus-variation microscopy (FVM) are presented and discussed. The origin of this technique, as well as its general metrological characteristics is briefly described. Additionally, information regarding the focus variation microscope used in the experiments - InfiniteFocus
The advances in the development of imaging devices resulted in the need of an automatic quality evaluation of displayed visual content in a way that is consistent with human visual perception. In this paper, an approach to full-reference... more
The advances in the development of imaging devices resulted in the need of an automatic quality evaluation of displayed visual content in a way that is consistent with human visual perception. In this paper, an approach to full-reference image quality assessment (IQA) is proposed, in which several IQA measures, representing different approaches to modelling human visual perception, are efficiently combined in order to produce objective quality evaluation of examined images, which is highly correlated with evaluation provided by human subjects. In the paper, an optimisation problem of selection of several IQA measures for creating a regression-based IQA hybrid measure, or a multimeasure, is defined and solved using a genetic algorithm. Experimental evaluation on four largest IQA benchmarks reveals that the multimeasures obtained using the proposed approach outperform state-of-the-art full-reference IQA techniques, including other recently developed fusion approaches.
Epileptic seizure attack is caused by abnormal brain activity of human subjects. Certain cases will lead to death. The detection and diagnosis is therefore an important task. It can be performed either by direct patient activity during... more
Epileptic seizure attack is caused by abnormal brain activity of human subjects. Certain cases will lead to death. The detection and diagnosis is therefore an important task. It can be performed either by direct patient activity during seizure or by electroencephalogram (EEG) signal analysis by neurologists. EEG signal processing and detection of seizures using machine learning techniques make this task easier than manual detection. To overcome this problem related to a neurological disorder, we have proposed the ensemble learning technique for improved detection of epilepsy seizures from EEG signals. In the first stage, EEG signal decomposition is done by utilizing empirical wavelet transform (EWT) for smooth analysis in terms of sub-bands. Further, features are extracted from each sub. Time and frequency domain features are the two categories used to extract the statistical features. These features are used in a stacked ensemble of deep neural network (DNN) model along with multil...
This paper presents a device that uses three cardiography signals to characterize several important parameters of a subject's circulatory system. Using electrocardiogram, finger photoplethysmogram, and ballistocardiogram, three heart... more
This paper presents a device that uses three cardiography signals to characterize several important parameters of a subject's circulatory system. Using electrocardiogram, finger photoplethysmogram, and ballistocardiogram, three heart rate estimates are acquired from beat-to-beat time interval extraction. Furthermore, pre-ejection period, pulse transit time (PTT), and pulse arrival time (PAT) are computed, and their long-term evolution is analyzed. The system estimates
As stereoscopic devices become widely used (immersion-based working environments, stereoscopically viewed movies, autostereoscopic screens, etc), exposure to stereoscopic images can become lengthy, and some eyestrain can set in. We... more
As stereoscopic devices become widely used (immersion-based working environments, stereoscopically viewed movies, autostereoscopic screens, etc), exposure to stereoscopic images can become lengthy, and some eyestrain can set in. We propose a method for reducing eyestrain induced by stereoscopic vision. After reviewing sources of eyestrain linked to stereoscopic vision, we will focus on one of these sources: images with high-frequency contents associated with large disparities. We will put forward an algorithm for removing irritating high frequencies in high disparity zones (i.e., for virtual objects appearing far from the real screen level). We will elaborate on our testing protocol to establish that our processing reduces eyestrain caused by stereoscopic vision, both objectively and subjectively. We will subsequently quantify the positive effects of our algorithm on the relief of eyestrain. As our processing alters the visual quality of the virtual world, we propose a new adaptation of our method to remove this drawback by coupling an eye tracking to our original processing to keep visual quality on the focus point.