Validation of a Simulink Model for Simulating the Two Typical Controlled Ventilation Modes of Intensive Care Units Mechanical Ventilators

Digital hydraulic valves: Advancements in research

Despite the great advantages it offers, such as high-power density, precise control and large force output, conventional hydraulic valve control suffers from low energy efficiency due to substantial energy losses that occurs as the pressurized oil flows through the hydraulic circuit and its components, particularly the control-ones. Conventional hydraulic technology typically utilizes analogue spool valves, such as proportional and servovalves, as control components in various industrial and aeronautical applications where high precision and fast response are required. However, the use of these valves leads to high power dissipation, caused by the significant pressure drop across the small narrow passages uncovered during valve control. To maintain the relevance of hydraulic technology across industries, researchers are investigating a novel research field, also referred to as digital hydraulic technology. By using some digital concepts into hydraulic technology, the goal of this innovative research field is to replace conventional analogue spool valves with robust and low-cost digital On/Off valves, thus minimizing power losses and enhancing the overall efficiency of hydraulic systems. This paper presents a thorough review of the research advancements in digital hydraulic technology, with a specific focus on valve control. Firstly, the standard definition of digital hydraulic technology and its two main categories are introduced. Then, the operating principles and the digital approaches used to control digital hydraulic valves are examined. Afterwards, the digital hydraulic valve architectures developed over the years are reviewed, along with an in-depth analysis of their performance. Finally, the potential application scenarios, advantages and challenges with digital hydraulic valves are explored, highlighting potential areas for future research and development.

Web Applications for Teaching the Respiratory System: Content Validation

The subject of respiratory mechanics has complex characteristics, functions, and interactions that can be difficult to understand in training and medical education contexts. As such, education strategies based on computational simulations comprise useful tools, but their application in the medical area requires stricter validation processes. This paper shows a statistical and a Delphi validation for two modules of a web application used for respiratory system learning: (I) “Anatomy and Physiology” and (II) “Work of Breathing Indexes”. For statistical validation, population and individual analyses were made using a database of healthy men to compare experimental and model-predicted data. For both modules, the predicted values followed the trend marked by the experimental data in the population analysis, while in the individual analysis, the predicted errors were 9.54% and 25.38% for maximal tidal volume and airflow, respectively, and 6.55%, 9.33%, and 11.77% for rapid shallow breathing index, work of breathing, and maximal inspiratory pressure, respectively. For the Delphi validation, an average higher than 4 was obtained after health professionals evaluated both modules from 1 to 5. In conclusion, both modules are good tools for respiratory system learning processes. The studied parameters behaved consistently with the expressions that describe ventilatory dynamics and were correlated with experimental data; furthermore, they had great acceptance by specialists.