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.

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

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.

Due to complexity of their mathematical computation, many QRS detectors are implemented in software and cannot operate in real time. The paper presents a real-time hardware based solution for this task. To filter ECG signal and to extract... more

Due to complexity of their mathematical computation, many QRS detectors are implemented in software and cannot operate in real time. The paper presents a real-time hardware based solution for this task. To filter ECG signal and to extract QRS complex it employs the Integer Wavelet Transform. The system includes several components and is incorporated in a single FPGA chip what makes it suitable for direct embedding in medical instruments or wearable health care devices. It has sufficient accuracy (about 95%), showing remarkable noise immunity and low cost. Additionally, each system component is composed of several identical blocks/cells what makes the design highly generic. The capacity of today existing FPGAs allows even dozens of detectors to be placed in a single chip. After the theoretical introduction of wavelets and the review of their application in QRS detection, it will be shown how some basic wavelets can be optimized for easy hardware implementation. For this purpose the migration to the integer arithmetic and additional simplifications in calculations has to be done. Further, the system architecture will be presented with the demonstrations in both, software simulation and real testing. At the end, the working performances and preliminary results will be outlined and discussed. The same principle can be applied with other signals where the hardware implementation of wavelet transform can be of benefit.

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.

Abstract: A wide range of direct pressure measuring electromechanical transducers is now commercially available in the market. In such electromechanical type direct indicating devices, the applied pressure is directly measured by a... more

Abstract: A wide range of direct pressure measuring electromechanical transducers is now commercially available in the market. In such electromechanical type direct indicating devices, the applied pressure is directly measured by a sensing element with a suitable mechanism into an ...

Abstract: A wide range of direct pressure measuring electromechanical transducers is now commercially available in the market. In such electromechanical type direct indicating devices, the applied pressure is directly measured by a... more

Abstract: A wide range of direct pressure measuring electromechanical transducers is now commercially available in the market. In such electromechanical type direct indicating devices, the applied pressure is directly measured by a sensing element with a suitable mechanism into an ...

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.