CPAP Hardware/Simulation and Control Design for Respiratory Disorders: A Review

Continuous Positive Airway Pressure (CPAP) ventilation remains a mainstay treatment for different respiratory disorders. Good pressure stability and pressure reduction during exhalation are of major importance condition to ensure the clinical efficacy and comfort of CPAP therapy. Obstructive Sleep Apnea (OSA) and today coronavirus (COVID-19) are the main two diseases mitigated by the CPAP. This paper introduced a systematic review of the CPAP design in terms of the hardware design, Simulation-based CPAP system, control algorithm, and the measured performance. The accuracy is used as measurement of performance and calculated from the pressure value. The accuracy was compared to the predefined U.S. Food and Drug Administration (FDA)-based threshold value in which it considers this value as a reference. The results related to the modern CPAP devices introduced in this study to explain the accuracy of experimental CPAP. These were compared with a commercial CPAP devices. Also, it was revealed how the results coincide with the error ratio defined by the FDA as an evaluation measurement. The FDA error ratio determines the performance of the optimized CPAP device. This work is the first review that presented the knowledge about engineering design of the CPAP system, so it will be the first in the literature.

The Optimal Carrier-Secret Ratio for Wireless Covert Channels Based on Constellation Shaping Modulation

Wireless covert communication is an emerging communication technique that prevents eavesdropping. This paper considers the bit error ratio (BER) problem of covert communication based on constellation shaping modulation (CSM). The impact of carrier-secret ratio (CSR) on BER is studied and the approximate solution of optimal CSR is obtained. Then, we extended the conclusion to typical communication scenarios with one and more relays where the undetectability and reliability were analyzed and inspected. It is proved that there also exists the optimal CSR in scenarios with relays. Additionally, it is found that the undetectability under the constraints of constant total power depends on the eavesdropper’s position, and we found an undetectability deterioration area (UDA) in the scenario of relays. Simulation results show the existence of optimal CSR and its impact on transmission performance.

Investigating student understanding of a heat engine: a case study of a Stirling engine

We report on the study of student difficulties regarding a heat engine in the context of a Stirling cycle by the method of measurement. An in-class test about a Stirling engine with a regenerator was taken by three classes, and the students were asked to perform one of the most basic activities—calculate the efficiency of the heat engine. Our data indicate that quite a few students have not developed a robust conceptual understanding of basic engineering knowledge of the heat engine. Notably, the error ratio of the class given a simple tutorial of engineering knowledge is smaller than those of the other two classes by more than 20%. In addition, both the written answers and post-test interviews show that most of the students cannot associate Carnot’s theorem with a Stirling cycle. Our results suggest that both scientific and engineering knowledge are important and should be included in instructional approaches, especially in the thermodynamics course taught in the countries and regions with a tradition of not paying much attention to experimental education or engineering training.

Dual-carrier modulation (DCM) is used to implement a species of tone reservation to reduce the PAPR of COFDM, wherein the reserved tones convey coded digital data (CDD) a second time. The same CDD is conveyed by carriers in a lower-frequency sub-band of the COFDM and by carriers in a higher- frequency sub-band. Each pair of carriers conveying the same CDD are separated by a subband width, enabling receivers better to ameliorate the effects of multipath reception. There is labeling diversity between the QAM symbol constellations that respectively govern modulation of carriers in the lower- frequency sub-band and modulation of carriers in the higher-frequency subband, which labeling diversity is designed to reduce PAPR of the COFDM. The labeling diversity also improves bit-error ratio (BER) for increased-size QAM symbol constellations used to increase CDD throughput despite the halving of CDD throughput owing to the use of DCM.

Dual-carrier modulation (DCM) is used to implement a species of tone reservation to reduce the PAPR of COFDM, wherein the reserved tones convey coded digital data (CDD) a second time. The same CDD is conveyed by carriers in a lower-frequency sub-band of the COFDM and by carriers in a higher- frequency sub-band. Each pair of carriers conveying the same CDD are separated by a subband width, enabling receivers better to ameliorate the effects of multipath reception. There is labeling diversity between the QAM symbol constellations that respectively govern modulation of carriers in the lower- frequency sub-band and modulation of carriers in the higher-frequency subband, which labeling diversity is designed to reduce PAPR of the COFDM. The labeling diversity also improves bit-error ratio (BER) for increased-size QAM symbol constellations used to increase CDD throughput despite the halving of CDD throughput owing to the use of DCM.

Improvement of Multipath Channel Performance for Optical MIMO-OFDM in LED Modulation with Fully Generalized Spatial-Frequency

This paper suggests a scheme to generalize the idea of LED index modulation concept by using the spatial multiplexing principle to relay complex OFDM signals through various channels such as AWGN, Rayleigh and Rician by splitting these signals into their real-imaginary and positive-negative components. In order to combat ISI as well as to increase the channel capacity. The MIMO-OFDM efficiency analysis, taking into account the constraint of the forward current of the LED is extracted. The accuracy of the theoretical results is verified by comparing the Bit Error Ratio (BER) reduction and improvement to the (SNR) results under varying condition of the channel. Using MIMO-OFDM as next-generation techniques, along with QAM aims to provide development of new concepts that will lead to the growth of future optical communication. Simulation results validate data rates gained over optical communication using LED modulation scheme and the pure transmission diversity method.

Rancang Bangun Alat Pendeteksi NOx dan CO Berbasis Mikrokontroler ESP32 dengan Notifikasi Via Telegram dan Suara

The design of NOx and CO detectors based on notifications via telegram and voice has been carried out. This detector consists of a gas sensor MQ-135 as a nitrogen oxide detector and an MQ-7 sensor as a carbon monoxide detector. Data processing is carried out using an ESP32 microcontroller which can send results to a telegram bot and play sound using speakers connected to the ISD 1820 sound module. The tool made can send notifications if the concentration of nitrogen oxides and carbon monoxide exceeds 50 ppm. The test is carried out by burning waste to produce smoke. Burning smoke contains various gases and particles that are harmful to the body. The characterization of the MQ-135 sensor was carried out by comparing the data obtained from the ISPU to measure nitrogen oxide gas and producing an error value of 9.09%. Meanwhile, the characterization of the MQ-7 sensor was carried out using a biogas analyzer and resulted in an error ratio of 3.26%. These results prove that the tools that have been designed can work well.

EXPRESS: Visually Guided Movement with Increasing Time-on-Task: Differential Effects on Movement Preparation and Movement Execution

Top-down cognitive control seems to be sensitive to the detrimental effects of fatigue induced by time-on-task (ToT). The planning and preparation of the motor responses may be especially vulnerable to ToT. Yet, effects of ToT specific to the different phases of movements have received little attention. Therefore, in three experiments, we assessed the effect of ToT on a mouse-pointing task. In Experiment 1, there were 16 possible target positions with variable movement directions. In Experiment 2, the layout of the targets was simplified. In Experiment 3, using cuing conditions we examined whether the effects of ToT on movement preparation and execution were caused by an increased orientation deficit or decreased phasic alertness. In each experiment, initiation of movement (preparatory phase) became slower, movement execution became faster and overall response time remained constant with increasing ToT. There was, however, no significant within-person association between the preparatory and execution phases. In Experiments 1 and 2, we found a decreasing movement time/movement error ratio, suggesting a more impulsive execution of the pointing movement. In addition, ToT was also accompanied with imprecise movement execution as indicated by the increased errors, mainly in Experiment 2. The results of Experiment 3 indicated that ToT did not induce orientation and phasic alerting deficits but rather was accompanied by decreased tonic alertness.

Virtual Reality (VR)-Based Environmental Enrichment in Older Adults with Mild Cognitive Impairment (MCI) and Mild Dementia

Background: Despite an alarming rise in the global prevalence of dementia, the available modalities for improving cognition and mental wellbeing of dementia patients remain limited. Environmental enrichment is an experimental paradigm that has shown promising anti-depressive and memory-enhancing effects in pre-clinical studies. However, its clinical utility has remained limited due to the lack of effective implementation strategies. Objective: The primary objective of this study was to evaluate the usability (tolerability and interactivity) of a long-term virtual reality (VR)- based environmental enrichment training program in older adults with mild cognitive impairment (MCI) and mild dementia. A secondary objective was to assess the effect of VR-based environmental enrichment on stabilization of cognitive functioning and improvement of mental wellbeing in older adults with MCI and mild dementia. Methods: A total of seven participants (four patients with MCI and three with mild dementia) received biweekly VR-based environmental enrichment over a course of 6 months. The tolerability and interactivity of the participants in the VR training was serially assessed via virtual reality sickness questionnaire (VRSQ) and recording of input-error ratio. Cognitive functioning was assessed through Montreal cognitive assessment (MoCA) before and after the study. Mental wellbeing was assessed through Warwick-Edinburgh Mental Well Being Scale (WEMWBS). Results: VR-based environmental enrichment was well-tolerated by the patients with significant decrease in VRSQ scores (p < 0.01) and input-error ratio (p < 0.001) overtime. VR training was also effective in stabilization of MoCA scores over the course of therapy (non-significant difference in the MoCA scores before and after the therapy) and was associated with a trend (p < 0.1) towards improvement in WEMWBS scores between the first and the last assessments. Qualitative observations by the care-givers further corroborated a noticeable improvement in mental wellbeing of patients. Conclusions: This pilot study shows that VR can be a feasible, tolerable, and potentially effective tool in long-term support of older adults with MCI and mild dementia.

An Analytical and Experimental Evaluation of a Heat Sink Under Constant Heat Flow and Forced Convection Heat Transfer

In this study, the exact transient differential equation was used to calculate the convection heat loss in a heat sink with a rectangular cross section fin. The result of the analytic solution was compared to the result from experiments conducted on a standard heat sink. The experiments were performed at a constant heat flow of 9000 W/m2 and a low airflow rate ranging from 12 to 100 cm3/s in seven steps. The comparative results showed that while there was good agreement between the experimental result and the exact solution, the average error ratio increased with an increase of the airflow rate. However, the maximum average error ratio between the experimental result and the exact solution did not exceed 6.4%. The maximum temperature distribution in the heat sink was obtained at a time of 900 s in all experiments.