The demand for utilizing medical ventilators for inter and intrahospital transport has risen quickly in recent periods of human society due to the consequences of the Covid-19 pandemic. Patients who have suffered during this pandemic need different modes of ventilation as a vital cure for their injured lungs. The development of control modes for medical ventilators requires a mathematical model which is able to represent the behavior of an air compressor accurately. In this paper, a parametric black-box method is used to obtain such a mathematical model, that is Nonlinear AutoRegressive with eXogenous input (NARX) model. This NARX model is constructed by experimental data from the air compressor using the bump-based two double-acting pistons (DAPP). The term selection and parameter estimation process are presented and conducted based on measured data. The identification model is also validated based on statistic criteria in the aspect of one-step-ahead prediction (OSA). The results show great tracking performances of identified NARX model.
In this paper, the design of a coaxial machine is proposed which is a debut for further applying on contra-rotating propulsion system such as underwater vehicle, torpedo or even aerial vehicle. The coaxial machine comprises of two independent rotors to eliminate the differential mechanism, reduce the power consumption, the balance the react force and make the system more stable. A model-based controller is adopted to drive the coaxial machine to generate the thrust force and balance the react force while hovers the coaxial machine chassis. The effectiveness and reliability of coaxial motor are evaluated through simulation and experimental results.
In high-power applications, multiple power MOSFETs are connected in parallel and treated as a single switch in order to handle much larger total currents. In this paper, a parallel power MOSFETs model from the turnoff state until they reach their steady state is introduced. The model represents the relationship between each power MOSFET's gate voltage and the current distribution among them. The study's key purpose is to use the model for dealing with the asymmetry in sharing current and power loss between these semiconductor devices during the steady state region.
Purpose In the COVID-19 outbreak periods, people's life has been deranged, leading to disrupt the world. Firstly, the number of deaths is growing and has the potential to surpass the highest level at any time. Secondly, the pandemic broke many countries' fortified lines of epidemic prevention and gave people a more honest view of its seriousness. Finally, the pandemic has an impact on life, and the economy led to a shortage in medical, including a lack of clinicians, facilities and medical equipment. One of those, a simple ventilator is a necessary piece of medical equipment since it might be useful for a COVID-19 patient's treatment. In some cases, the COVID-19 patients require to be treated by modern ventilators to reduce lung damage. Therefore, the addition of simple ventilators is a necessity to relieve high work pressure on medical bureaucracies. Some low-income countries aim to build a simple ventilator for primary care and palliative care using locally accessible and low-cost components. One of the simple principles for producing airflow is to squeeze an artificial manual breathing unit (AMBU) iterative with grippers, which imitates the motion of human fingers. Unfortunately, the squeezing angle of grippers is not proportional to the exhaust air volume from the AMBU bag. This paper aims to model the AMBU bag by a mathematical equation that enables to implement on a simple controller to operate a bag-valve-mask (BVM) ventilator with high accuracy performance. Design/methodology/approach This paper provides a curvature function to estimate the air volume exhausting from the AMBU bag. Since the determination of the curvature function is sophisticated, the coefficients of the curvature function are approximated by a quadratic function through the experimental identification method. To obtain the high accuracy performance, a linear regression model and a least square method are employed to investigate the characteristic of the BVM ventilator's grippers angle with respect to the airflow volume produced by the AMBU bag. Findings This paper investigates the correlation between the exhausting airflow of the AMBU bag and the grippers angle of the BVM ventilator. Originality/value The experimental results validated that the regression model of the characteristic of the exhausting airflow of the AMBU bag with respect to the grippers' angle has been fitted with a coefficient over 98% within the range of 350–750 ml.
Typically, an electromagnet can be used as an electrical actuator to provide contactless forces, it is crucial to identify and govern the characteristics that impact the attraction force between the electromagnet and the target object in order to ensure precision in contactless force control. This research undertakes the development of an electromagnetic force measurement apparatus (EFMA) to investigate the factors affecting electromagnets actively. The paper assesses the influence of both distance and current on the electromagnet attraction force. Several experimental tests were put in place to determine the accuracy of the model and successfully draw conclusions about the relationship between parameters.
Ventilators are drawn to many researchers during the Covid-19 pandemic because it's essential equipment that's accustomed to treat severe Covid-19 patients. In low-income countries, there's a shortage of pricy respiratory devices resulting in exceeding the provision of taking care of Covid-19's patients in ICU. This paper attempts to design and implement an appropriate respiratory device referred to as a bag valve mask (BVM) ventilator for those who are Covid-19 patients in medical care, those patients have a requirement of safe transport and also palliative care. The BVM ventilator comprises a man-made manual breath unit (AMBU) bag and paddles for squeezing the AMBU bag which is popular in medical aid settings. The BVM ventilator is required to travel airflow through the system to the patient's lung with the specified volume for every breath cycle within a threshold air pressure. Since the AMBU bag is straightforward to be deformed over time, it's difficult to get mathematical modelling for constructing a reliable controller. Therefore, a model-free control (MFC) control approach is utilized successfully to style a controller for our BVM ventilator model with a PEEP valve and a HEPA filter. Some experimental scenarios are administered to gauge the effectiveness of the proposed controller for the BVM ventilator to control the airflow and control air pressure mode.
Numerous studies about solar panel cleaning robot (SPCR) have been conducted globally to enhance the performance of photovoltaic panels (PV panels). However, there is a reality: scant attention has been paid to the large pressure and vibration that SPCR movements induce, not only on the photovoltaic panel surface but also on the mounting structure. Most of the research is focused on evaluating the “cleanliness” of the PV surface by using a clearing robot or the effects of natural factors (wind, dust, etc.) on the PV panels. Nonetheless, the large pressure and vibration constitute one of the primary factors contributing to the degradation of photovoltaic panel longevity and efficiency, especially affecting poorly installed PV arrays. To address these issues, this study proposes the design of a multi-suspension unit for the SPCRs equipped with track-wheeled, which might reduce vibration on the PV panel surface generated by the SPCRs’ motion and brushing action during operation. The multi-suspension unit facilitates the expansion of the contact area between the track-wheeled and the PV panel surface; hence, the negative effect is reduced owing to the vibration-absorbing properties of the rubber track pads. In the case of a static SPCR state, with only the impact of rotating brushes on vibration, the effectiveness of the multi-suspension unit can reduce vibration by a maximum of 72.63. Moreover, a metric (Δz) is proposed to evaluate the change in deflection of PV panels over time. The results show that the number of significant changes in PV panel deflection gradually decreases or disappears, while the number of small changes increases. In the case of SPCR operating on portrait PV modules, the number of occurrences of Δz (greater than 0.5 mm) is reduced from 18 counts to 5 counts, while the number of occurrences of Δz (less than 0.5 mm) increased from 61 counts to 91 counts. Overall, the proposed multi-system suspension is effective in reducing or eliminating large deflections while keeping the vibration frequency constant.
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