A computational fluid dynamics assessment of 3D printed ventilator splitters and restrictors for differential multi-patient ventilation

Background The global pandemic of novel coronavirus (SARS-CoV-2) has led to global shortages of ventilators and accessories. One solution to this problem is to split ventilators between multiple patients, which poses the difficulty of treating two patients with dissimilar ventilation needs. A proposed solution to this problem is the use of 3D-printed flow splitters and restrictors. There is little data available on the reliability of such devices and how the use of different 3D printing methods might affect their performance. Methods We performed flow resistance measurements on 30 different 3D-printed restrictor designs produced using a range of fused deposition modelling and stereolithography printers and materials, from consumer grade printers using polylactic acid filament to professional printers using surgical resin. We compared their performance to novel computational fluid dynamics models driven by empirical ventilator flow rate data. This indicates the ideal performance of a part that matches the computer model. Results The 3D-printed restrictors varied considerably between printers and materials to a sufficient degree that would make them unsafe for clinical use without individual testing. This occurs because the interior surface of the restrictor is rough and has a reduced nominal average diameter when compared to the computer model. However, we have also shown that with careful calibration it is possible to tune the end-inspiratory (tidal) volume by titrating the inspiratory time on the ventilator. Conclusions Computer simulations of differential multi patient ventilation indicate that the use of 3D-printed flow splitters is viable. However, in situ testing indicates that using 3D printers to produce flow restricting orifices is not recommended, as the flow resistance can deviate significantly from expected values depending on the type of printer used. Trial registration Not applicable.

Моделирование источника ультрахолодных нейтронов на реакторе ПИК

The paper presents the simulation of a complex of reserch with ultracold neutrons at the reactor PIK (Gatchina, Russia). The complex is being built on the basis of a high-intensity source of ultracold neutrons at the channel GEK-4. A Monte Carlo model has been developed, which includes a source, a neutron guide system and an experimental setup for search for the electric dipole moment of a neutron, taking into account their real location in the main hall of the reactor. Using the developed computer model the density of ultracold neutrons in the setup was obtained, which is 200 ^-3. It is 50 times higher than at the source at the Institut Laue-Langevin (Grenoble, France). This density will allow to achieve a sensitivity of measurements in the experiment of 1·10^-27 е·cm/year.

Static-dynamic model for endpoint control used in Smederevo's BOF shop

This paper describes the computer model for BOF control that was in use at Smederevo, Serbia, during the period 1994-2006. The model was developed at the Institute of Metallurgy of the Smederevo Steelwork in mid-1994 and was motivated by the fact that the plant in Smederevo, by that time, had many years of experience in endpoint control using Intermediate Stop Practice (ISP). The vision for the model was to continuously improve and adapt to the working conditions of production through self-learning and adjustments. The model belongs to the well-known family of Static-Dynamic models (SDMs). It is aimed to reduce the "oxygen off-to-start tap" time and thus increase productivity and reduce production costs. The paper briefly describes the metallurgical software, operator operations and provides some information on the model's effectiveness.

Accuracy of identification of the state of the internal combustion engine with the customized model using the measuring expert system

Рассмотрены вопросы уменьшения погрешности идентификации технического состояния двигателя внутреннего сгорания и его составных частей как объекта экспертизы путем настраивания параметров применяемой в измерительной экспертной системе виртуальной модели ДВС. Для настройки модели предложено применение градиентного метода, обеспечивающего наиболее быструю минимизацию погрешности идентификации Purpose and methods. Improving the accuracy of identification for the technical condition of the internal combustion engine (ICE) in operational conditions using the engine measurement expert system (EMSE) is addressed by adjusting the computer dynamic model of the internal combustion engine. Results. Algorithmic schemes of computer models for the state of the ICE are obtained using the equations of its dynamics, which takes into account the factors such as the movement of the fuel supply body, the force on the hook - the load. The structural schemes of modeling at the input of a step-by-step action are presented. A promising method of tuning the model in the EMSE is proposed, which consists of measuring its working processes, in particular the angular acceleration of the crankshaft, for a specific brand of ICE. Then the corresponding set of models of its technical condition is obtained: normal, permissible, limit, pre-accident and emergency. By adjusting the values of the coefficients of these models in the EMSE, they achieve their coincidence with the actual state of the ICE. The identification error is minimized using the gradient method of steepest descent. The presence of several computer models is a practical advantage in the examination of the technical condition of the tested engines allowing its effective implementation in operational conditions. In this case, based on the experience of operation, the computer model closest to the actual state of the ICE is adjusted. At the same time, the efficiency of localization of ICE malfunctions increases, since the coefficients reflecting the state of the engine components and systems are consistently adjusted. Conclusions. The application of the proposed methodology using the criterion of minimizing the identification error by the gradient method allows implementation of this effective method for identifying the state of the ICE. It increases the reliability of determining the technical state of the ICE and its components by adjusting the computer model

An analytical model for mountain wave in stratified atmosphere

An analytical, two-dimensional computer model has been developed for real time prediction of 'mountain wave due to Principal mountains over Kashmir valley. Simulation of the L2 profile has been made with realistic, non-zero values at higher levels and exponentially decreasing values at lower levels. Unlike Doos (1961), present solution has no restriction on the value of wave number (k). Validity of the model has been tested with the satellite observed waves in seven cases and actual aircraft report in one case.

JUSTIFICATION OF THE FUNCTIONAL MARMALADE RECIPE

The article analyzes the mass fraction of sugar in the composition of the most common types of marmalade in retail chains. The hypothesis of the relationship between the statistics of childhood obesity in Russia and the increase in the consumption of "hidden" sugars is presented. The article substantiates the relevance of introducing healthy sweets into the diet of children. The results of a patent search and laboratory study of the sugar content in industrial marmalade by capillary electrophoresis are presented. A computer model of the marmalade recipe with a low sugar content and high nutritional value was obtained.

Model of the traction and external power supply system joint operation

The paper presents a description of mathematical model designed to study the joint operation of 25 kV alternating current traction power supply systems and 110 - 750 kV power supply systemsThe design concept of three-phase and single-phase PU-generators on the basis of the EMF source behind inductive resistance as well as three-phase and single-phase loads is considered. Based on the above mathematical expressions, a computer model has been developed to analyze the joint operation of three-phase networks of external power supply and single-phase traction networks. The model is implemented in the software package MATLAB -Simulink. Using this computer model the influence of power overflows in the 110 - 330 kV network of PJSC “Karelenergo” and PJSC “FGC UES” on the equalizing currents in the traction network of the Knyazhaya-Idel’ section of the October railroad was analyzed. Brief analysis of modeling results is presented.