Test and Analysis of Stepper Motor’s Noise in HVAC’s Ventilation Valve

With the application of automotive air conditioning being more popular, higher requirements on automotive air conditioning’s comfort have been put forward, noise is an important criterion about comfort. BDC motor controlling ventilation valve’s noise is mainly caused by brush and commutator, but stepper motor doesn’t have it and stepper motor is cheap and easy-controlling. In this paper, the principle of microstepping drive technology is discussed in detail, the control circuit block diagram and the application of the stepping motor’s control system are introduced. The noise of BDC motor and stepper motor controlling ventilation valve is measured in the semi-anechoic room, BDC motor produces peak noise at the start and stop during the working of motor, stepper motor’s noise is slight and smooth-going; current waveforms have been measured in the microstepping drive, the results show microstepping drive makes current waveform more smooth-going and stepper motor’s noise is lower. So it is a tendance stepper motor will replace BDC motor to control ventilation valve, and the microstepping drive can meet different requirements for merchant’s control.

The Effect of Volume Controlled and Pressure Controlled Ventilation Modes on Cerebral Oximetry and Blood Gas Status in Laparoscopic Cholecystectomy, A Randomized Controlled Trial

Background: To compare the volume-controlled and pressure-controlled ventilation modes with near infrared spectroscopy (NIRS) cerebral oximetry and blood gas status in laparoscopic cholecystectomyMethods: Seventy patients (n=70), who underwent elective laparoscopic cholecystectomy operation were randomized into two groups (volume control ventilation - group V, pressure control ventilation - group P). Demographic data (age, gender, body mass index) and operative data (anesthesia, surgery, and insufflation durations) were recorded. Patients’ single derivation electrocardiogram, pulse oximetry, non-invasive arterial pressure, NIRS cerebral oximetry and end-tidal CO2 parameters were recorded. Measurements were done at the start of anesthesia (T0), at the end of intubation (T1), 5 minutes after the insufflation (T2), at the time just before desufflation (T3) and 5 minutes after desufflation (T4).The patients’ heart rate, systolic and diastolic arterial pressure, saturation of pulse oximetry, and NIRS values were recorded for time points. Additionally, arterial gas results and mechanical ventilation parameters were recorded as well. Results: No significant difference was found in age, sex, body mass index. Operation, anesthesia and insufflation durations were similar for the groups. In Group P, NIRS right T1-2-3 averages and NIRS left T2-3 averages were significantly higher than Group V (p=0.030, p=0.001, p=0.001, p=0.006, p=0.002 respectively). In Group P T1-T2-T4, mean peak pressures and mean plateau pressures were significantly lower than Group V (p=0.003, p=0.001, p<0.001, p=0.011, p=0.001, p<0.001 respectively).Conclusion: Mechanical ventilation that performed in pressure-control ventilation mode is resulted with better tissue oxygenation than volume-control ventilation mode. In pressure-control ventilation mode, peak pressure and plateau pressure were lower.Registration of study at ClinicalTrials.gov was made at 25/01/2021 with the NCT04723043 number.

VentQsys: Low-cost open IoT system for $$CO_2$$ monitoring in classrooms

In educational context, a source of nuisance for students is carbon dioxide ($$CO_2$$ C O 2 ) concentration due to closed rooms and lack of ventilation or circulatory air. Also, in the pandemic context, ventilation in indoor environments has been proven as a good tool to control the COVID-19 infections. In this work, it is presented a low cost IoT-based open-hardware and open-software monitoring system to control ventilation, by measuring carbon dioxide ($$CO_2$$ C O 2 ), temperature and relative humidity. This system provides also support for automatic updating, auto-self calibration and adds some Cloud and Edge offloading of computational features for mapping functionalities. From the tests carried out, it is observed a good performance in terms of functionality, battery durability, compared to other measuring devices, more expensive than our proposal.

Changes in dead space components during pressure-controlled inverse ratio ventilation: A secondary analysis of a randomized trial

Background We previously reported that there were no differences between the lung-protective actions of pressure-controlled inverse ratio ventilation and volume control ventilation based on the changes in serum cytokine levels. Dead space represents a ventilation-perfusion mismatch, and can enable us to understand the heterogeneity and elapsed time changes in ventilation-perfusion mismatch. Methods This study was a secondary analysis of a randomized controlled trial of patients who underwent robot-assisted laparoscopic radical prostatectomy. The inspiratory to expiratory ratio was adjusted individually by observing the expiratory flow-time wave in the pressure-controlled inverse ratio ventilation group (n = 14) and was set to 1:2 in the volume-control ventilation group (n = 13). Using volumetric capnography, the physiological dead space was divided into three dead space components: airway, alveolar, and shunt dead space. The influence of pressure-controlled inverse ratio ventilation and time factor on the changes in each dead space component rate was analyzed using the Mann-Whitney U test and Wilcoxon’s signed rank test. Results The physiological dead space and shunt dead space rate were decreased in the pressure-controlled inverse ratio ventilation group compared with those in the volume control ventilation group (p < 0.001 and p = 0.003, respectively), and both dead space rates increased with time in both groups. The airway dead space rate increased with time, but the difference between the groups was not significant. There were no significant changes in the alveolar dead space rate. Conclusions Pressure-controlled inverse ratio ventilation reduced the physiological dead space rate, suggesting an improvement in the total ventilation/perfusion mismatch due to improved inflation of the alveoli affected by heterogeneous expansion disorder without hyperinflation of the normal alveoli. However, the shunt dead space rate increased with time, suggesting that atelectasis developed with time in both groups.

Diaphragm neurostimulation during mechanical ventilation reduces atelectasis and transpulmonary plateau pressure, preserving lung homogeneity and PaO2/FiO2

Tidal volume delivered by mechanical ventilation to a sedated patient is distributed in a non-physiological pattern, causing atelectasis (underinflation) and overdistension (overinflation). Activation of the diaphragm during mechanical ventilation provides a way to reduce atelectasis and alveolar inhomogeneity, protecting the lungs from ventilator-induced lung injury while also protecting the diaphragm by preventing ventilator-induced diaphragm dysfunction. We studied the hypothesis that diaphragm contractions elicited by transvenous phrenic nerve stimulation, delivered in synchrony with volume-control ventilation, would reduce atelectasis and lung inhomogeneity in a healthy, normal-lung pig model. Twenty-five large pigs were ventilated for 50 hours with lung-protective volume-control ventilation combined with synchronous transvenous phrenic-nerve neurostimulation on every breath, or every second breath. This was compared to lung-protective ventilation alone. Lung mechanics and ventilation pressures were measured using esophageal pressure manometry and electrical impedance tomography. Alveolar homogeneity was measured using alveolar chord length of preserved lung tissue. Lung injury was measured using inflammatory cytokine concentration in bronchoalveolar lavage fluid and serum. We found that diaphragm neurostimulation on every breath preserved PaO2/FiO2 and significantly reduced the loss of end-expiratory lung volume after 50 hours of mechanical ventilation. Neurostimulation on every breath reduced plateau and driving pressures, improved both static and dynamic compliance and resulted in less alveolar inhomogeneity. These findings support that temporary transvenous diaphragm neurostimulation during volume-controlled, lung-protective ventilation may offer a potential method to provide both lung- and diaphragm-protective ventilation.

Towards measuring real-time occupant levels to reduce ventilation fan energy consumption in existing institutional gathering spaces - a field study using thermal sensors.

Ventilation systems in buildings have been traditionally designed for the maximum projected number of occupants; while buildings often have fewer occupants than the maximum and in some cases can be unoccupied for extended periods. Changing the rate of outdoor air to reflect changes in the number of occupants in a space is referred to as demand control ventilation (DCV). A field study was performed using thermal sensors to determine the number of occupants using lecture rooms of an institutional building. The occupant data was used to calculate minimum ventilation for the lecture rooms using current ventilation standards from ASHRAE Standard 62.1. It was found that by current standards, the required ventilation is considerably less than the original design ventilation. Based on occupant data and variables specific to the lecture rooms, it was found that the ventilation can be reduced by at least 40% creating a potential for significant energy savings.

Towards measuring real-time occupant levels to reduce ventilation fan energy consumption in existing institutional gathering spaces - a field study using thermal sensors.

Ventilation systems in buildings have been traditionally designed for the maximum projected number of occupants; while buildings often have fewer occupants than the maximum and in some cases can be unoccupied for extended periods. Changing the rate of outdoor air to reflect changes in the number of occupants in a space is referred to as demand control ventilation (DCV). A field study was performed using thermal sensors to determine the number of occupants using lecture rooms of an institutional building. The occupant data was used to calculate minimum ventilation for the lecture rooms using current ventilation standards from ASHRAE Standard 62.1. It was found that by current standards, the required ventilation is considerably less than the original design ventilation. Based on occupant data and variables specific to the lecture rooms, it was found that the ventilation can be reduced by at least 40% creating a potential for significant energy savings.