Photoplethysmography in Normal and Pathological Sleep

This article presents an overview of the advancements that have been made in the use of photoplethysmography (PPG) for unobtrusive sleep studies. PPG is included in the quickly evolving and very popular landscape of wearables but has specific interesting properties, particularly the ability to capture the modulation of the autonomic nervous system during sleep. Recent advances have been made in PPG signal acquisition and processing, including coupling it with accelerometry in order to construct hypnograms in normal and pathologic sleep and also to detect sleep-disordered breathing (SDB). The limitations of PPG (e.g., oxymetry signal failure, motion artefacts, signal processing) are reviewed as well as technical solutions to overcome these issues. The potential medical applications of PPG are numerous, including home-based detection of SDB (for triage purposes), and long-term monitoring of insomnia, circadian rhythm sleep disorders (to assess treatment effects), and treated SDB (to ensure disease control). New contact sensor combinations to improve future wearables seem promising, particularly tools that allow for the assessment of brain activity. In this way, in-ear EEG combined with PPG and actigraphy could be an interesting focus for future research.

Summary of over Fifty Years with Brain-Computer Interfaces—A Review

Over the last few decades, the Brain-Computer Interfaces have been gradually making their way to the epicenter of scientific interest. Many scientists from all around the world have contributed to the state of the art in this scientific domain by developing numerous tools and methods for brain signal acquisition and processing. Such a spectacular progress would not be achievable without accompanying technological development to equip the researchers with the proper devices providing what is absolutely necessary for any kind of discovery as the core of every analysis: the data reflecting the brain activity. The common effort has resulted in pushing the whole domain to the point where the communication between a human being and the external world through BCI interfaces is no longer science fiction but nowadays reality. In this work we present the most relevant aspects of the BCIs and all the milestones that have been made over nearly 50-year history of this research domain. We mention people who were pioneers in this area as well as we highlight all the technological and methodological advances that have transformed something available and understandable by a very few into something that has a potential to be a breathtaking change for so many. Aiming to fully understand how the human brain works is a very ambitious goal and it will surely take time to succeed. However, even that fraction of what has already been determined is sufficient e.g., to allow impaired people to regain control on their lives and significantly improve its quality. The more is discovered in this domain, the more benefit for all of us this can potentially bring.

Relay vibration protection simulation experimental platform based on signal reconstruction of MATLAB software

For conceptual analysis of the principle of relay vibration protection, this article establishes the simulation system model of directional current protection in MATLAB/Simulink environment through the protection algorithm. Various outcomes have been achieved for the proposed approach during the faulty conditions. The outcomes obtained during the fault period reveals that the waveform of three-phase current changes greatly, and the amplitude of three-phase current at power supply side increases sharply. After 0.02s signal acquisition and processing, the action signal acts after 0.07s, and the fault is removed. In case of two-phase short-circuit, two-phase grounding short-circuit and other faults, the fault can be removed smoothly after signal acquisition and processing. In this paper, the directional current protection simulation system based on microcomputer protection model is built, and the changes of voltage, current and action signal are demonstrated through GUI interface, and analyzed and verified.

Added Value of QEEG for the Differential Diagnosis of Common Forms of Dementia

Introduction Quantitative electroencephalography (QEEG) has been documented as a helpful tool in the differential diagnosis of Alzheimer’s disease (AD) with common forms of dementia. The main objective of the study was to assess the role of QEEG in AD differential diagnosis with other forms of dementia: Lewy body dementia (LBD), Parkinson’s disease dementia (PDD), frontotemporal dementia (FTD), and vascular dementia (VaD). Methods We searched PubMed, Embase, and PsycNET, for articles in English published in peer-reviewed journals from January 1, 1980 to April 23, 2019 using adapted search strategies containing keywords quantitative EEG and Alzheimer. The risk of bias was assessed by applying the QUADAS tool. The systematic review was conducted in line with the PRISMA methodology. Results We identified 10 articles showcasing QEEG features used in diagnosing dementia, EEG slowing phenomena in AD and PDD, coherence changes in AD and VaD, the role of LORETA in dementia, and the controversial QEEG pattern in FTD. Results vary significantly in terms of sociodemographic features of the studied population, neuropsychological assessment, signal acquisition and processing, and methods of analysis. Discussion This article provides a comparative synthesis of existing evidence on the role of QEEG in diagnosing dementia, highlighting some specific features for different types of dementia (eg, the slow-wave activity has been remarked in both AD and PDD, but more pronounced in PDD patients, a diminution in anterior and posterior alpha coherence was noticed in AD, and a lower alpha coherence in the left temporal-parietal-occipital regions was observed in VaD). Conclusion QEEG may be a useful investigation for settling the diagnosis of common forms of dementia. Further research of quantitative analyses is warranted, particularly on the association between QEEG, neuropsychological, and imaging features. In conjunction, these methods may provide superior diagnostic accuracy in the diagnosis of dementia.

Development of an Optical Signal-Based IPS from an MCU-SoC

In this work, we have studied the integration of an optical signal-based Indoor Positioning System (IPS) capable of supporting multi-access discrimination techniques. The research analyzes the different techniques and conditions that can be used to develop an IPS using a microcontroller unit (MCU)-based system-on-chip (SoC) systems. The main goal is to be able to integrate into the MCU both the hardware and software requirements for an IPS detector. In this way, different strategies that can implement multi-access discrimination using Frequency-division multiple access (FDMA) have been tested, such as I/Q demodulation, digital filtering, and discrete Fourier transform (DFT). This analysis has found a good technique to be executed in an MCU-based SoC, the DFT implemented through the Goertzel’s algorithm. The empirical tests carried out concluded that, using only one an MCU with the required HW and tuned SW, 15 position measurements per second were computed, with high accuracy in the 3-D positioning, with errors of less than 1 cm in a test area of 3.5 × 3.5 m 2 . The main contribution of the paper is the implementation of the optical signal based IPS in an MCU-SoC that includes signal acquisition and processing. The digital filtering or spectral processing for up to 16 received signals makes this IPS system very attractive from a design and cost point of view.

Design, modeling, and verification of a test bench for braking simulation of 1/4 vehicle

Brake-by-wire systems are one of the key components in intelligent/unmanned vehicles that have attracted worldwide attention. Testing and evaluation of brake-by-wire systems are a significant step during the development of the technology of vehicular braking and further the advancement of intelligent/unmanned vehicles. Using the test bench to simulate different road adhesion coefficients (i.e. road surfaces) and to complete the testing and evaluation of the vehicle braking systems is of great significance and importance. A test bench for simulation of vehicular braking of 1/4 vehicle is presented and investigated in this article. It is composed of a motor, two rollers, a 1/4 vehicle suspension system, a magnetic powder clutch, a flywheel, sensors, a signal acquisition and processing system, and a controller. The wheel and vehicle speeds are simulated by the rollers and flywheel speeds, respectively. The translational kinetic energy of 1/4 vehicle is simulated by the rotational kinetic energy of the flywheel. The signal acquisition and processing system is used to acquire and process the experimental signals, such as rotational speeds and torques during tests. The magnetic powder clutch with adjusted applied currents in the test bench is used to real-timely simulate roads with different adhesion coefficients. Based on the working principle of the test bench and the fundamentals of vehicle dynamics, the prototype of the test bench is established and the simulation approach of the translational kinetic energy of 1/4 vehicle is investigated. The mathematical model of the real-time simulation about roads with different adhesion coefficients based on the magnetic powder clutch with real-time controllable transmitted torque is established. With the built 1/4 vehicle braking systems based on the test bench and road, and the corresponding established models, the comparison and analysis of the simulation results of various road surfaces are conducted. Experiments are sequentially implemented to verify the feasibility and effectiveness of the test bench.