Maolin Cai

Detection of sputum by interpreting the time-frequency distribution of respiratory sound signal using image processing techniques

Motivation Sputum in the trachea is hard to expectorate and detect directly for the patients who are unconscious, especially those in Intensive Care Unit. Medical staff should always check the condition of sputum in the trachea. This is time‐consuming and the necessary skills are difficult to acquire. Currently, there are few automatic approaches to serve as alternatives to this manual approach. Results We develop an automatic approach to diagnose the condition of the sputum. Our approach utilizes a system involving a medical device and quantitative analytic methods. In this approach, the time‐frequency distribution of respiratory sound signals, determined from the spectrum, is treated as an image. The sputum detection is performed by interpreting the patterns in the image through the procedure of preprocessing and feature extraction. In this study, 272 respiratory sound samples (145 sputum sound and 127 non‐sputum sound samples) are collected from 12 patients. We apply the method of leave‐one out cross‐validation to the 12 patients to assess the performance of our approach. That is, out of the 12 patients, 11 are randomly selected and their sound samples are used to predict the sound samples in the remaining one patient. The results show that our automatic approach can classify the sputum condition at an accuracy rate of 83.5%. Availability and implementation The matlab codes and examples of datasets explored in this work are available at Bioinformatics online. Contact yesoyou@gmail.com or douglaszhang@umac.mo Supplementary information Supplementary data are available at Bioinformatics online.

Influence of Bronchial Diameter Change on the airflow dynamics Based on a Pressure-controlled Ventilation System

Bronchial diameter is a key parameter that affects the respiratory treatment of mechanically ventilated patients. In this paper, to reveal the influence of bronchial diameter on the airflow dynamics of pressure-controlled mechanically ventilated patients, a new respiratory system model is presented that combines multigeneration airways with lungs. Furthermore, experiments and simulation studies to verify the model are performed. Finally, through the simulation study, it can be determined that in airway generations 2 to 7, when the diameter is reduced to half of the original value, the maximum air pressure (maximum air pressure in lungs) decreases by nearly 16%, the maximum flow decreases by nearly 30%, and the total airway pressure loss (sum of each generation pressure drop) is more than 5 times the original value. Moreover, in airway generations 8 to 16, with increasing diameter, the maximum air pressure, maximum flow, and total airway pressure loss remain almost constant. When the diameter is reduced to half of the original value, the maximum air pressure decreases by 3%, the maximum flow decreases by nearly 5%, and the total airway pressure loss increases by 200%. The study creates a foundation for improvement in respiratory disease diagnosis and treatment.

Coupling Effect of Double Lungs on a VCV Ventilator with Automatic Secretion Clearance Function

For patients with mechanical ventilation, secretions in airway are harmful and sometimes even mortal, its of great significance to clear secretion timely and efficiently. In this paper, a new secretion clearance method for VCV (volume-controlled ventilation) ventilator is put forward, and a secretion clearance system with a VCV ventilator and double lungs is designed. Furthermore, the mathematical model of the secretion clearance system is built and verified via experimental study. Finally, to illustrate the influence of key parameters of respiratory system and secretion clearance system on the secretion clearance characteristics, coupling effects of two lungs on VCV secretion clearance system are studied by an orthogonal experiment, it can be obtained that rise of tidal volume adds to efficiency of secretion clearance while effect of area, compliance, and suction pressure on efficiency of secretion clearance needs further study. Rise of compliance improves bottom pressure of secretion clearance while rise of area, tidal volume, and suction pressure decreases bottom pressure of secretion clearance. This paper can be referred to in researches of secretion clearance for VCV.

Numerical simulation of volume-controlled mechanical ventilated respiratory system with 2 different lungs: Numerical Simulation of mechanical ventilated respiratory system

Mechanical ventilation is a key therapy for patients who cannot breathe adequately by themselves, and dynamics of mechanical ventilation system is of great significance for life support of patients. Recently, models of mechanical ventilated respiratory system with 1 lung are used to simulate the respiratory system of patients. However, humans have 2 lungs. When the respiratory characteristics of 2 lungs are different, a single-lung model cannot reflect real respiratory system. In this paper, to illustrate dynamic characteristics of mechanical ventilated respiratory system with 2 different lungs, we propose a mathematical model of mechanical ventilated respiratory system with 2 different lungs and conduct experiments to verify the model. Furthermore, we study the dynamics of mechanical ventilated respiratory system with 2 different lungs. This research study can be used for improving the efficiency and safety of volume-controlled mechanical ventilation system.

Pressure Dynamic Characteristics of Pressure Controlled Ventilation System of a Lung Simulator

Mechanical ventilation is an important life support treatment of critically ill patients, and air pressure dynamics of human lung affect ventilation treatment effects. In this paper, in order to obtain the influences of seven key parameters of mechanical ventilation system on the pressure dynamics of human lung, firstly, mechanical ventilation system was considered as a pure pneumatic system, and then its mathematical model was set up. Furthermore, to verify the mathematical model, a prototype mechanical ventilation system of a lung simulator was proposed for experimental study. Last, simulation and experimental studies on the air flow dynamic of the mechanical ventilation system were done, and then the pressure dynamic characteristics of the mechanical system were obtained. The study can be referred to in the pulmonary diagnostics, treatment, and design of various medical devices or diagnostic systems.

Output dynamic control of a late model sustainable energy automobile system with nonlinearity

Air-liquid pressurization convertor has been applied in energy boosting which is widely used in sustainable energy automobile. In this article, output dynamic control method is analyzed by model simulation and experimental validation to set foundation for optimization, in which the pneumatic and hydraulic nonlinear combination equations, total nonlinear frictions on pistons, and load nonlinear equilibrium equation are considered. Moreover, influences on output dynamic control characteristics of the late automobile model with nonlinearity are studied. The conclusion can be made as follows: first, the built model is effectively verified by comparison of experimental and simulation results. Second, as one of the key power system parameters, longer piston stroke will lead to better output dynamic property within a certain limit. Third, area ratio is considered to be approximately 8, which can avoid the unsteadiness of the output dynamic characteristics. Furthermore, suitably bigger orifice will greatly promote the characteristic property of the air-liquid pressurization convertor. Finally, under the condition of this article, input pressure can be set to 0.65u2009MPa to obtain a better power system combination property. This study can provide reference for the optimization of dynamic characteristics of the sustainable energy automobile.

Fuzzy logic speed control for the engine of an air-powered vehicle

To improve the condition of air and eliminate exhaust gas pollution, this article proposes a compressed air power system. Instead of an internal combustion engine, the automobile is equipped with a compressed air engine, which transforms the energy of compressed air into mechanical motion energy. A prototype was built, and the compressed air engine was tested on an experimental platform. The output torque and energy efficiency were obtained from experimental results. When the supply pressure was set at 2u2009MPa and the speed was 420u2009ru2009min−1, the output torque, the output power, and the energy efficiency were 56u2009Nu2009m, 1.93u2009kW, and 25%, respectively. To improve the efficiency of the system, a fuzzy logic speed control strategy is proposed and simulated. The experimental study verified that the theoretical evaluation of the system was reasonable, and this research can be referred to as the design and control of air-powered vehicles.

Flow characteristics of expansion energy used pneumatic booster

The most common booster is called input pressure reduced (IPR) booster. However, this type of booster has its own shortages, such as its small output flow, when the boosting ratio is higher, the shortage becomes more distinct. Recent research on pneumatic boosters mainly focused on the factors that influence the characteristics of the boosters, some new kinds of pneumatic booster structures were designed, but the efficiency and output flow of these boosters are still not improved sufficiently. In order to improve the output flow of the pneumatic booster, a new kind of booster, expansion energy used (EEU) booster, is proposed. Non-linear differential equations of the pneumatic booster are set up. By using the software MATLAB/Simulink for simulation, the motion characteristics of the pistons, the characteristics of the output flow of the boosters are obtained for analysis of a principle. The principle, which is used to elevate the output flow of the two kinds of boosters, is that the average pressure of the air in the driving chambers of the EEU booster is higher than that of the IPR booster. The simulation and experimental research of the output flow characteristics are done. The simulation and experimental results are in a good accordance. And the simulation and experimental results show that when the air source pressure and the output pressure are set at 0.6 MPa and 0.8 MPa, respectively, with the increase of the terminal pressure of the air in the driving chamber, the output flow of the IPR booster ascends stably. As the terminal pressure of the air in the driving chamber goes up, the output flow of the EEU booster rises, and later it almost remains constant. In addition, with the same terminal pressure, the output flow of the EEU booster is greater than that of the IPR booster, and the difference decreases when the terminal pressure grows. At last, the output pressure is set at 0.8 MPa, under the optimum work state of the EEU booster, the output flow of the two kinds of boosters all declines with the rise of the boosting ratio. Furthermore, the output flow of the EEU booster is higher than that of IPR booster by 95 L/min approximately. The proposed research lays the foundation for optimistic of the EEU booster.

Working characteristics of two types of compressed air engine

To avoid environment pollution caused by internal combustion engine vehicles, compressed air engines (CAEs) have attracted much attention over the past decade. Two kinds of compressed air engines, single cylinder piston-type CAE (SCAE) and double crank link CAE (DCAE), have been investigated. However, SCAEs have low energy efficiency and output power; particularly, when rotational speed is high. To solve these shortcomings, the DCAE is proposed, which can obtain higher output power at higher rotational speeds. Using co-simulation technology, the average output power, energy efficiency, and cylinder pressure of the two kinds of CAEs were obtained. The average output power and efficiency characteristics of the SCAE were obtained by simulation and experiment; the simulation results were consistent with the experimental results, which verified that the united simulation model is accurate and effective. The results show that the pressure inside the DCAE cylinder is barely influenced by the rotational speed, and the output torque remains generally stable with an increase in the rotational speed. The average energy efficiency of both kinds of CAE declines with an increase in the rotational speed when the supply pressure is set at 2 MPa. The air power efficiency of the DCAE is about 1.86–2.86 times that of the SCAE. When the rotational speed is 800 rpm, the air power efficiency of the DCAE is 2.86 times than that of the SCAE. It is clear that the DCAE can improve the CAE performance under high rotational speeds.

Modelling and Simulation of Volume Controlled Mechanical Ventilation System

Volume controlled mechanical ventilation system is a typical time-delay system, which is applied to ventilate patients who cannot breathe adequately on their own. To illustrate the influences of key parameters of the ventilator on the dynamics of the ventilated respiratory system, this paper firstly derived a new mathematical model of the ventilation system; secondly, simulation and experimental results are compared to verify the mathematical model; lastly, the influences of key parameters of ventilator on the dynamics of the ventilated respiratory system are carried out. This study can be helpful in the VCV ventilation treatment and respiratory diagnostics.