SWITCHED-CAPACITOR CIRCUITS WITH REDUCED INFLUENCES OF PARASITIC CAPACITANCES, SWITCH RESISTANCES AND AMPLIFIER NON-IDEALITIES

Two design techniques are described for decreasing and possibly eliminating the effects of element imperfections in switched-capacitor (SC) circuits. The first technique is devoted to the operational amplifier non-idealities. It is centered on decreasing the number of amplifiers in the circuits by multiplexing their use. The second approach is based on the minimization of the sum of the square of the differences between the time (or the frequency) response of the circuit with and without non-idealities. This technique can be used to control over the effects of finite switch resistances, finite gain-bandwidth product of the amplifiers as well as parasitic capacitances. Computer results have revealed that the responses of the optimized circuits are nearly the same as that of the ideal ones. Illustrative examples are given illustrating the efficiency of the proposed techniques

Dust Effect on Solar Energy Systems and Mitigation Methods

Received: 2 February 2023. Accepted: 29 March 2023.Solar energy systems present a potential solution to global challenges in energy production and addressing environmental issues. However, such systems' performance could deteriorate in harsh weather conditions, which may lead to short- and long-term degradation. Particular attention should be paid to dust accumulation affecting both types of solar systems: Photovoltaic (PV) and Concentrated Solar Power systems (CSP). This review discusses the influencing factors affecting dust accumulation and the dust impact on solar systems. The comparison of dust accumulation effect on both technologies is then assessed. The reported dust accumulation studies showed more performance deterioration in CSP systems than in PV systems. In both cases, dust accumulation leads to a drop in optical characteristics resulting in a loss of energy yield. Potential mitigation methods and their advantages and disadvantages are also reviewed. It is concluded and recommended from the review analysis that dust accumulated on solar systems should be considered in the design and operation phases to define appropriate cleaning methods and frequencies.The authors would like to thank the University of Sharjah, Project #20020406150, for its financial support

An Efficient Technique for Compressing ECG Signals Using QRS Detection, Estimation, and 2D DWT Coefficients Thresholding

This paper presents an efficient electrocardiogram (ECG) signals compression technique based on QRS detection, estimation, and 2D DWT coefficients thresholding. Firstly, the original ECG signal is preprocessed by detecting QRS complex, then the difference between the preprocessed ECG signal and the estimated QRS-complex waveform is estimated. 2D approaches utilize the fact that ECG signals generally show redundancy between adjacent beats and between adjacent samples. The error signal is cut and aligned to form a 2-D matrix, then the 2-D matrix is wavelet transformed and the resulting wavelet coefficients are segmented into groups and thresholded. There are two grouping techniques proposed to segment the DWT coefficients. The threshold level of each group of coefficients is calculated based on entropy of coefficients. The resulted thresholded DWT coefficients are coded using the coding technique given in the work by (Abo-Zahhad and Rajoub, 2002). The compression algorithm is tested for 24 different records selected from the MIT-BIH Arrhythmia Database (MIT-BIH Arrhythmia Database). The experimental results show that the proposed method achieves high compression ratio with relatively low distortion and low computational complexity in comparison with other methods

A Wireless Emergency Telemedicine System for Patients Monitoring and Diagnosis

Recently, remote healthcare systems have received increasing attention in the last decade, explaining why intelligent systems with physiology signal monitoring for e-health care are an emerging area of development. Therefore, this study adopts a system which includes continuous collection and evaluation of multiple vital signs, long-term healthcare, and a cellular connection to a medical center in emergency case and it transfers all acquired raw data by the internet in normal case. The proposed system can continuously acquire four different physiological signs, for example, ECG, SpO2, temperature, and blood pressure and further relayed them to an intelligent data analysis scheme to diagnose abnormal pulses for exploring potential chronic diseases. The proposed system also has a friendly web-based interface for medical staff to observe immediate pulse signals for remote treatment. Once abnormal event happened or the request to real-time display vital signs is confirmed, all physiological signs will be immediately transmitted to remote medical server through both cellular networks and internet. Also data can be transmitted to a family member’s mobile phone or doctor’s phone through GPRS. A prototype of such system has been successfully developed and implemented, which will offer high standard of healthcare with a major reduction in cost for our society

Experimental and theoretical performance evaluation of parabolic trough mirror as solar thermal concentrator to thermoelectric generators

This paper presents the prospects of harnessing radiative heat from the sun with a parabolic trough mirror, as a solar thermal concentrator, in comparison to the mathematical model and experimental quartz-halogen concentrator model for the electrical energy conversion utilizing thermoelectric generators (TEG). The construction and design of TEG-setup along with Parabolic trough mirrors and quartz-halogen lamps are presented. The Parabolic trough mirror used as a focal point at a distance of 19.05 cm. With eight quartz-halogen concentrated heat, the maximum performance achieved at ΔT of 11.8 K, Voc of 292 mV and Isc of 95.8 mA, recorded at the concentrated hot-side surface temperature of 317.8 K. When compared to the natural solar concentrated heat, higher temperature of 473.15 K at the hot-side surface temperature of TG was achieved. It is concluded that the heat concentration of the parabolic mirror increases with an increase in the intensity of heat using natural solar radiations. The Voc of 1.76 V and Isc of 1.1 A at a temperature difference of 110 K were measured, which are in good agreement with validated mathematical results. The parabolic through mirror utilized is smaller in size and thus collected lesser sun rays than the larger dish style mirror, and hence the heat in the focal point was very low, for better results, parabolic trough mirror with higher surface area would be important for future experiments

A short survey on fault diagnosis in wireless sensor networks

Fault diagnosis is one of the most important and demand- able issues of the network. It makes the networks reliable and robust to operate in the normal way to handle almost all types of faults or failures. Additionally, it helps sensor nodes to work smoothly and efficiently till the end of their lifetime. This short survey paper not only presents a clear picture of the recent proposed techniques, but also draws comparisons and contrasts among them to diagnose the potential faults. In addition, it proposes some potential future-work directions which would lead to open new research directions in the field of fault diagnosis

On-demand fuzzy clustering and ant-colony optimisation based mobile data collection in wireless sensor network

In a wireless sensor network (WSN), sensor nodes collect data from the environment and transfer this data to an end user through multi-hop communication. This results in high energy dissipation of the devices. Thus, balancing of energy consumption is a major concern in such kind of network. Appropriate cluster head (CH) selection may provide to be an efficient way to reduce the energy dissipation and prolonging the network lifetime in WSN. This paper has adopted the concept of fuzzy if-then rules to choose the cluster head based on certain fuzzy descriptors. To optimise the fuzzy membership functions, Particle Swarm Optimisation (PSO) has been used to improve their ranges. Moreover, recent study has confirmed that the introduction of a mobile collector in a network which collects data through short-range communications also aids in high energy conservation. In this work, the network is divided into clusters and a mobile collector starts from the static sink or base station and moves through each of these clusters and collect data from the chosen cluster heads in a single-hop fashion. Mobility based on Ant-Colony Optimisation (ACO) has already proven to be an efficient method which is utilised in this work. Additionally, instead of performing clustering in every round, CH is selected on demand. The performance of the proposed algorithm has been compared with some existing clustering algorithms. Simulation results show that the proposed protocol is more energy-efficient and provides better packet delivery ratio as compared to the existing protocols for data collection obtained through Matlab Simulations

Individual identification via electrocardiogram analysis

Background: During last decade the use of ECG recordings in biometric recognition studies has increased. ECG characteristics made it suitable for subject identification: it is unique, present in all living individuals, and hard to forge. However, in spite of the great number of approaches found in literature, no agreement exists on the most appropriate methodology. This study aimed at providing a survey of the techniques used so far in ECG-based human identification. Specifically, a pattern recognition perspective is here proposed providing a unifying framework to appreciate previous studies and, hopefully, guide future research. Methods: We searched for papers on the subject from the earliest available date using relevant electronic databases (Medline, IEEEXplore, Scopus, and Web of Knowledge). The following terms were used in different combinations: electrocardiogram, ECG, human identification, biometric, authentication and individual variability. The electronic sources were last searched on 1st March 2015. In our selection we included published research on peer-reviewed journals, books chapters and conferences proceedings. The search was performed for English language documents. Results: 100 pertinent papers were found. Number of subjects involved in the journal studies ranges from 10 to 502, age from 16 to 86, male and female subjects are generally present. Number of analysed leads varies as well as the recording conditions. Identification performance differs widely as well as verification rate. Many studies refer to publicly available databases (Physionet ECG databases repository) while others rely on proprietary recordings making difficult them to compare. As a measure of overall accuracy we computed a weighted average of the identification rate and equal error rate in authentication scenarios. Identification rate resulted equal to 94.95 % while the equal error rate equal to 0.92 %. Conclusions: Biometric recognition is a mature field of research. Nevertheless, the use of physiological signals features, such as the ECG traits, needs further improvements. ECG features have the potential to be used in daily activities such as access control and patient handling as well as in wearable electronics applications. However, some barriers still limit its growth. Further analysis should be addressed on the use of single lead recordings and the study of features which are not dependent on the recording sites (e.g. fingers, hand palms). Moreover, it is expected that new techniques will be developed using fiducials and non-fiducial based features in order to catch the best of both approaches. ECG recognition in pathological subjects is also worth of additional investigations