Unit Capacity Research Articles

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In modern military operations, units of the National Guard of Ukraine often have to perform tasks in densely populated urban areas, which complicates reconnaissance and monitoring. The prevalence of electronic warfare tactics that disrupt satellite signals such as GPS and GLONASS further exacerbates these problems. Traditional unmanned aerial vehicles, which rely heavily on satellite navigation, are vulnerable to electronic countermeasures, potentially compromising mission success. This article deals with the urgent issue of increasing the capacity of units of the National Guard of Ukraine that operate in such conditions. The challenge is the need for reliable and robust means of reconnaissance and navigation in environments where satellite signals are blocked or unavailable. To address this issue, the paper explores the integration of autonomous unmanned aerial vehicles equipped with optical-electronic navigation systems, offering a viable alternative to satellite-based unmanned aerial vehicles. The advantages of such integration are numerous. First, it significantly improves navigation accuracy even in the absence of satellite signals through a combination of inertial navigation systems, high-frequency terrain navigation, and image-based navigation. These systems provide precise unmanned aerial vehicles movements, a critical requirement for reconnaissance missions in complex urban landscapes. In addition, resistance to electronic warfare stands out as a decisive advantage. Unmanned aerial vehicles with opto-electronic navigation systems combined with anti-jamming features become resilient to electronic warfare tactics, providing uninterrupted reconnaissance and monitoring in conflict environments. However, the integration of optical-electronic navigation systems has certain limitations. Weather conditions such as fog or heavy rain may interfere with navigation. In addition, data processing needs can strain onboard computing resources, requiring advanced processors for optimal performance. Additionally, damage to optical sensors due to environmental factors can disrupt navigation, requiring redundancy or repair. In summary, the integration of autonomous unmanned aerial vehicles with opto-electronic navigation systems offers a promising solution to the challenges faced by National Guard units in urban environments. Enhanced accuracy, resistance to electronic warfare, and adaptability to changing conditions make this approach a compelling choice to enhance mission success and ensure the safety of National Guard personnel in complex and contested scenarios.

A review on research and development of CFB combustion technology in China

The development history and present status of the circulating fluidized bed combustion (CFBC) technology in China are reviewed. This technology has been developed for nearly 40 years since the early 1980s in China, and its development history can be divided into five stages, including a learning stage, an improvement stage, a scale-up stage, a maturing stage, and an ultra-low emission and ultra-supercritical stage. There are currently >3500 units of CFB boilers operating in the country, with unit capacities covering the range of 35–2000 t/h in steam output, mainly used for coal firing. Among the units, the world's first 600 MW supercritical CFB boiler was successfully demonstrated in 2014 and was regarded as a milestone of CFBC technology in the world. CFB boilers are playing an important role in thermal and power generation in China. Several achievements in engineering application and fundamental research are achieved. The reviewed history and achievements could be used as references for researchers and engineers in future CFBC technology development. At the end of the paper, the prospects of CFBC technology in the area of carbon neutralization are discussed. Though the application in coal combustion is shrinking, CFBC technology will play an important role in CO 2 reduction and carbon neutralization. • Present status of circulating fluidized bed combustion (CFBC) technology in China is reported. • CFBC technology development history in China is introduced by five stages. • Major engineering applications of CFBC technology in each stage are reviewed. • Typical fundamental research and achievements on CFBC technology in China are introduced. • The prospects of CFBC technology for carbon neutralization are discussed.

The COVID-19 Pandemic and Landspitali's Operating Room and Intensive Care Unit

The COVID-19 pandemic, one of the most serious public health hazards of recent times, led to a high number of hospitalisations. The pressure on intensive care units has been significant. In many countries, including Iceland, there was a need to increase the capacity of these units to meet the growing demand for intensive care spaces, especially at the start of the pandemic. At Landspitali, the National University Hospital of Iceland (hereafter referred to as Landspitali), increasing unit capacity was a large-scale and extensive project where project management methodologies were utilised to assess risks and develop response plans. Using information gathered from interviews, this study explores the experience of managers in Landspitali’s surgical and intensive care unit in preparing for the pandemic and their evaluations of the project\'s success. The interviews were conducted in the autumn of 2020 after the first wave of the pandemic had passed in Iceland. The study utilised a qualitative methodology. Eight managers from Landspitali’s surgical and intensive care unit participated in semi-structured interviews. The study employs thematic analysis to analyse the findings. The data analysis reveals four themes. The first theme, ‘dealing with the unknown’, illustrates the uncertainty that was prevalent at the beginning of the pandemic. The second, ‘one step ahead’, reveals how the managers utilised resources both within and outside the hospital to prepare the intensive care unit for COVID-19 patients. The third theme, ‘fighting the virus’, highlights the challenges the managers encountered throughout the process. Lastly, the ‘in this together’ theme focuses on how the staff came together to accomplish the project. The initial uncertainty during the preparation phase posed difficulties for the managers. Working in accordance with existing response plans and utilising the findings of the situation analysis made it possible for managers to organise how space, personnel, and supplies would be utilised and thus increase the surge capacity of the units. The respondents\' main challenges were facility adaptation and ensuring adequate staffing. Cooperation and solidarity among the staff, along with well-timed preventive measures implemented by the authorities, proved crucial to the success of Landspitali’s intensive care unit in dealing with the pandemic.

Performance enhancement of solar thermal systems using phase change materials- a review

This article reviews the studies carried out with respect to the area of phase change material (PCM) coupled to solar thermal systems. Solar energy is a pure form of energy which could overcome the scarcity and ecological issues of conventional energy sources, but it requires energy storage and this stored energy is supplied to the systems for later use. The solar thermal storage system can improve the performance of a solar thermal application as the solar radiation varies throughout a day. Because of their high latent heat, PCMs offer the best alternative for thermal energy storage. PCM has the capability to hold more heat per unit capacity relative to conventional storage due to its latent heat form of storage. To enable a higher saturation of renewable energy sources and fulfil the demand, one possibility is to couple them with energy storage systems. Thus, the LHS material is used due to their heat storage ability. In this review focus is given to classification of PCM, their properties and their application in solar thermal systems.

EFFICIENCY OF A WIND PLANT IN REAL CONDITIONS WITH ADDITIONAL COSTS AND THE MARKET PRICE OF ELECTRICITY

In its development, the global energy sector is constantly demonstrating the growth of electricity consumption. Traditional power plants in this process ensure an increase in greenhouse emissions and aggravation of climate problems, which are becoming more relevant every year. Against this background, modern alternative energy sources, namely wind power plants, contribute to reducing the impact of traditional power plants and encourage solving environmental problems. The development of global wind energy is accompanied by the growth of unit capacities of generators of wind power plants. The paper analyzes the efficiency of a wind power plant based on modern wind generators for predetermined location conditions, taking into account operating costs based on operational experience and based on the assessment of the power plant's participation in the balancing market of electricity with a waiver of the "green tariff". Calculations of the technical and economic indicators of an imaginary designed 4-unit wind power plant with various wind generators under the wind conditions of a predetermined industrial site located in the Carpathian region of Ukraine were carried out. The calculations take into account the modern typical characteristics of wind generators, additional operating costs and the estimated cost of electricity purchase of the station under the "green tariff" and in the conditions of a balancing electricity market to compare economic efficiency. In order to make an optimal design technical decision with a comparative assessment, three types of wind generators were determined for installation at an imaginary wind farm - Enercon E-175 EP5, Vestas V136-4.5 MW and Vestas V172-7.2 MW. In the conditions of the predetermined construction site of the projected wind farm on the Carpathian ridges of Ukraine, the measured and calculated annual probability distribution of wind speed according to the analytical Weibull distribution is applied, and the characteristics of the annual productivity of the 4-unit wind farm for the adopted three types of wind generators are given. The technical and economic characteristics were obtained in the work: capital investment, operating costs, characteristics of electricity production, the gross profit during the annual operation of the wind power plant with three options for installing wind generators was calculated, making it possible to estimate the payback time of the investment in the construction of the wind plant. So, for a 4-unit station with generators of the Enercon E-175 EP5, the payback period is 3.3 years, and with wind generators of the Vestas V136-4.5 MW - 3.4 years, as well as for the Vestas V172-7.2 MW in operating conditions of the "green tariff" and, respectively, 2.9 years, 2.9 years and 3.0 years under conditions of sale of electricity at balancing market prices. Additional operating costs for the disposal of worn wind turbine blades do not have a significant impact on the overall cost indicators and amount to 5-7% of the total costs.

Estimation of the minimum required bus capacity between the hinterland and the centre of a functional urban region – a comparative study of the five largest Serbian cities

ABSTRACT This study presents a simply applicable method for comparing the capacity and potential of suburban bus services. The starting point for the analysis of the capacity is raw data from individual transport companies on the frequency of bus connections and the connectivity of centres with other parts of urban regions. A minimum seat capacity constant, based on the definition of a bus as a means of public transport, enables getting estimation of minimal required capacity. The concept of demographic gravitation serves as a comparative element of gravitational and capacity potential between settlements within urban regions, namely, demographic force, which measures the population of two settlements with the square of the distance between them with adequately made calibration based on real traffic flows. The results provide a comprehensive picture of the distribution of the suburban bus network, with detailed values of the required capacity in the lowest administrative units.

Monitoring of the Forgotten Immune System during Critical Illness-A Narrative Review.

Immune organ failure is frequent in critical illness independent of its cause and has been acknowledged for a long time. Most patients admitted to the ICU, whether featuring infection, trauma, or other tissue injury, have high levels of alarmins expression in tissues or systemically which then activate innate and adaptive responses. Although necessary, this response is frequently maladaptive and leads to organ dysfunction. In addition, the counter-response aiming to restore homeostasis and repair injury can also be detrimental and contribute to persistent chronic illness. Despite intensive research on this topic in the last 40 years, the immune system is not routinely monitored in critical care units. In this narrative review we will first discuss the inflammatory response after acute illness and the players of maladaptive response, focusing on neutrophils, monocytes, and T cells. We will then go through commonly used biomarkers, like C-reactive protein, procalcitonin and pancreatic stone protein (PSP) and what they monitor. Next, we will discuss the strengths and limitations of flow cytometry and related techniques as an essential tool for more in-depth immune monitoring and end with a presentation of the most promising cell associated markers, namely HLA-DR expression on monocytes, neutrophil expression of CD64 and PD-1 expression on T cells. In sum, immune monitoring critically ill patients is a forgotten and missing piece in the monitoring capacity of intensive care units. New technology, including bed-side equipment and in deep cell phenotyping using emerging multiplexing techniques will likely allow the definition of endotypes and a more personalized care in the future.

Програмно-інформаційний комплекс моделювання систем теплопостачання

Software and information complex for modeling of the heat supply systems functioning, which allows ensuring the optimal selection of aggregates and their operation modes. It will ensure the production and redistribution of energy in accordance with the schedule of consumers. Simulation of optimized operating modes of a self-sufficient heat supply system for a cottage village based on local energy resources and with minimal use of external energy sources was performed. The use of the software and information complex made it possible to calculate the parameters that provide optimized coverage of the heat load schedule of the cottage village based on local energy resources. The simulation performed using the example of the predicted values of the installed thermal capacity of the power units and the actual ambient temperature schedule. The developed new software and information complex provides an opportunity for hourly simulation and research of optimal modes of operation of heat units of autonomous heat supply systems. In the developed software and information complex, a model of optimization of operating modes is applied, which belongs to the class of problems of optimal loading of generating capacities of power systems with the criterion of minimizing costs for production, accumulation and consumption of heat and electricity. An example of simulation results using the heat load schedule for the selected day of March 20, 2018 is given. The obtained results indicate a decrease in the specific cost of hourly heat supply with an increase in the part of thermal energy supplied at the expense of renewable energy sources, and accordingly, a decrease in the part of gas, and in the general case of any other generation based on fossil fuel technologies, in the total volume of heat supply. Thus, the effectiveness of the use of renewable energy sources based on local energy resources as part of the heat supply system of the cottage village confirmed. Keywords: autonomous heat supply, efficiency of renewable energy sources based on local energy resources

DESIGN FEATURES OF MODERN FOREIGN AGRICULTURAL TRACTORS

Analysis of the state and trends in the development of agricultural machines and the technical means that serve them shows that there is a constant process of creating more productive and economical equipment. This is primarily ensured by increasing unit capacity, increasing working and transport speeds, reducing time losses for auxiliary operations, reducing maintenance costs to a minimum; ensuring minimal impact on soil and plants; increasing reliability and wear resistance, as well as an increase in versatility and the appearance of special tractors for specific work; expansion of production of wheeled tractors with four driving wheels, wider use of hydraulic systems, electronics, automation, new materials, creation of comfortable working conditions and ease of management; ensuring labor safety. The main type of tractor in the most widespread range of capacities remains the wheeled one of the traditional layout scheme, the improvement of which is carried out taking into account the latest achievements of science and technology. There is a further update of articulated tractors with all driving wheels of the same size, with leading manufacturers experimenting with the installation of triangular track drives instead of wheels, which significantly increases their traction qualities. Characteristic features of tractors of the new generation are their universality and block-modular structure. So, depending on the market, different engines from well-known companies and unified transmissions are installed on one model of European tractors. Therefore, in this market, there is a tendency for manufacturers to cooperate with the aim of further increasing versatility, reliability, and simplifying operation: increasing the interval for changing engine oil to 500 hours, transmission oil to 2,000 hours, hydraulic oil to 1,000 hours. Cooperation also contributes to the expansion of opportunities for competition in the markets of different countries. The new generation of powerful wheeled tractors with a classic and system layout provides high efficiency mainly in technological operations with medium traction forces in combined, tillage and sowing units, which are equipped with implements with active working bodies, with front and rear GDP, as well as in transport operations.

Durability of latent heat storage systems

Latent heat storage represents technology with significantly higher energy storage density. The thermal energy storage capacity of building structures and storage units integrated into building services contribute to the energy flexibility of buildings. This paper presents results from laboratory experiments focused on the compatibility of heat storage media represented by phase change materials (PCMs) with materials of container. Material compatibility of selected PCMs with the plastics and metals were tested by a long-term experiment. Two organic-based and two inorganic-based phase change materials were selected for tests of compatibility with selected metals (aluminium, copper and brass) and plastics (PP-H, PE-HD, and PVC-U). Plastic-PCM compatibility was determined by gravimetric method. For evaluation of metal-PCM compatibility, calculation of corrosion rate was applied. The less mass changes and lower penetration of PCMs to the matrix was observed for inorganic-based PCMs compared to organic-based PCMs. In case of compatibility between metals and PCMs, the highest values of corrosion rate were calculated for copper immersed in inorganic-based PCMs Rubitherm SP25.

Advancement and capacity allocation analysis of variable speed hydropower units for suppressing wind power fluctuations

The advancement and capacity allocation of variable-speed hydropower units (VSHUs) for suppressing wind power fluctuations are studied. First, a wind–hydropower generation system model, comprising the doubly fed VSHU (DFVSHU) and full-size power VSHU (FSVSHU) is established. Then, three typical operating conditions, namely the wind speed step-up, wind speed sudden drop, and wind gust, are selected to quantify the advantages of the VSHU in suppressing wind power fluctuations using the power range, power standard deviation, and power fluctuation time. Finally, a VSHU capacity allocation scheme in which some FSHUs are transformed into VSHUs for the same total capacity of hydropower units is proposed. A VSHU capacity allocation formula based on this scheme is also proposed. Simulations and comparisons reveal that the VSHU can effectively suppress wind power fluctuations over short time scales, and its effectiveness is 90% higher than that of the FSHU. In addition, the simulation based on the measured wind speed data verifies the effectiveness of the capacity allocation formula. This study provides a new method for suppressing wind power fluctuations over short time scales and provides theoretical guidance for the application of VSHUs through capacity allocation.

COVID-19 and the forgone health benefits of elective operations

Background and aimThe first SARS-CoV-2 pandemic wave in Germany involved a tradeoff between saving the lives of COVID-19 patients by providing sufficient intensive care unit (ICU) capacity and foregoing the health benefits of elective procedures. This study aims to quantify this tradeoff.MethodsThe analysis is conducted at both the individual and population levels. The analysis calculates quality-adjusted life years (QALYs) to facilitate a comparison between the health gains from saving the lives of COVID-19 patients in the ICU and the health losses associated with postponing operative procedures. The QALYs gained from saving the lives of COVID-19 patients are calculated based on both the real-world ICU admissions and deaths averted from flattening the first wave. Scenario analysis was used to account for variation in input factors.ResultsAt the individual level, the resource-adjusted QALY gain of saving one COVID-19 life is predicted to be 3 to 15 times larger than the QALY loss of deferring one operation (the average multiplier is 9). The real-world QALY gain at the population level is estimated to fall within the range of the QALY loss due to delayed procedures. The modeled QALY gain by flattening the first wave is 3 to 31 times larger than the QALY loss due to delayed procedures (the average multiplier is 17).ConclusionDuring the first wave of the pandemic, the resource-adjusted health gain from treating one COVID-19 patient in the ICU was found to be much larger than the health loss from deferring one operation. At the population level, flattening the first wave led to a much larger health gain than the health loss from delaying operative procedures.

АНАЛІЗ СТАНУ ПРАВОПОРЯДКУ ЦЕНТРАЛЬНОГО РЕГІОНУ ЗБРОЙНИХ СИЛ УКРАЇНИ: АДМІНІСТРАТИВНО-ДЕЛІКТНИЙ АСПЕКТ

The authors note that the current state of law and order in the Armed Forces of Ukraine and other military formations has both theoretical and practical problems, the research and solution of which are urgent. This concerns the maintenance of a high level of military discipline among military personnel and persons equivalent to them, ensuring high combat readiness and combat capacity of military units and units, especially during the period of active hostilities and in conditions of deployment of military units where the latter are not conducted. The article states that in 2015, for the first time, administrative responsibility for committing military administrative offenses was introduced. Changes have also been made regarding the procedural registration of the commission of military administrative offenses. Military personnel’s tormental activity is one of the reasons for the adoption by the Verkhovna Rada of Ukraine of an addition to the Code of Ukraine on Administrative Offenses, namely Chapter 13-Б “Military Administrative Offenses”. The analysis of the statistical data of the Central region enabled the authors to claim that the most common military administrative offense is the offense provided for in Article 172-20 of the Code of Ukraine on Administrative Offenses “Drinking alcoholic, low-alcohol beverages or the use of narcotic drugs, psychotropic substances or their analogues”, Article 172-11 of the Code of Ukraine on Administrative Offenses “Leaving without a permission a military unit or place of service”, 172-15 of the Code of Ukraine on Administrative Offenses “Negligent attitude to military service”. As conclusions, the authors note that the institution of administrative liability of military personnel has not been considered for a long time and requires further reformation. The stated circumstances require improvement of the norms of the current administrative legislation, which regulates military personnel’s liability for committing administrative offenses Key words: military personnel, administrative offense, administrative liability, military discipline, Armed Forces of Ukraine, military duty, Military Law and Order Service.

Fast state-of-charge balancing control strategies for battery energy storage systems to maximize capacity utilization

To improve the carrying capacity of the distributed energy storage system, fast state of charge (SOC) balancing control strategies based on reference voltage scheduling (RVSF) function and power command iterative calculation (PIC) are proposed in this paper, respectively. First, as an improvement to the traditional droop SOC balancing control, the working principle and parameters design of the RVSF-based method is introduced, which can realize the energy interaction among the storage units during the balancing process. The PIC-based fast SOC balancing strategy is then proposed for a system with a current bus sensor. The PIC strategy realizes the fastest SOC equalization speed by ensuring there is always at least one storage unit operating in the maximum power flow during the SOC balancing process. In addition, the proposed strategy is extended to the system with inconsistent energy storage unit capacity. Finally, circuit-based simulation and code-based models for a plan with different energy storage units are constructed in PLECS and MATLAB simulation software, respectively. The hardware in the loop simulation results validate the correctness and feasibility of the proposed strategies and show that the proposed techniques can significantly improve the load capacity and duration of the system under many operating conditions.

A Novel Fully Hardware-Implemented SVD Solver Based on Ultra-Parallel BCV Jacobi Algorithm

Efficient FPGA-based floating-point singular value decomposition (SVD) is challenging for its enormous complexity with the rapid growth of the matrix dimension. Numerous hardware architectures have been proposed to improve the performance of SVD by increasing capacity of computation units, reusing data, and enhancing bandwidth. These designs, however, are not optimum due to their low parallelism, poor data access efficiency, and inferior iterations scheduling. In this express, we propose a block column vector Hestenes-Jacobi (BCV Jacobi) algorithm that decomposes an arbitrary large matrix into several blocks, enhances the access efficiency by customizing the distinctive data structure, and improves the system-level parallelism by simplifying the iteration scheduling. The proposed BCV Jacobi algorithm also achieves better scalability and efficiency. Experimental results show that the performance of the proposed FPGA based SVD processor is superior to other SVD implementations in terms of parallelism, data access efficiency, matrix size, and execution time. When compared with state of the art SVD accelerator engine, the proposed algorithm speeds up the runtime over <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$2{\times }$ </tex-math></inline-formula> on average.

Analisis Pergantian Alat Pengencang Baut-U 4 Spindel Menjadi 1 Spindel di Station Rear axle PT.Daimler Commercial Vehicles Manufacturing Indonesia

Bolt tightening is a process that is widely and important to use or do in the vehicle assembly process.. Power tools with synchronous systems are powerful equipment that is able to help the process of tightening several bolts simultaneously without human energy. This study aims to analyze the 1 spindle bolt fastener to fasten 4 U-bolts on Rear axle in Axor 4028TT type trucks at PT. Daimler Commercial Vehicles Manufacturing Indonesia.The experiment was conducted to test the fastening of the bolt 1 spindle with a replica method of the 4 spindle bolt fastening synchronization system. Sampling used is 6 units with each unit has 4 bolts on the right and left to be compared with the results of U-bolt tightening using the tool 4 spindles.The study used a digital moment key to measure the residual firmness value of the bolt. The data analysis technique is to compare the value of the bolt tightening deviation across two tool systems. The average deviation value on the 1 spindle bolt fastener is 0.31% while on 4 spindles it is 0.13%. The average value of deviations from the digital moment key verification results on 1 spindle is 2.4% while 4 spindles are 3.4%. The results of the comparison showed that the results of fastening bolts 1 spindle provide a deviation of no more than ± 18.6%. Despite having a deviation value greater than 4 spindles, but considering the capacity of units produced in the pandemic period and cost components if tool repairs are made, then the 1 spindle bolt tightening tool is worth considering for use..

Research on the Torsional Vibration Response Characteristics of Parallel Operation Steam Turbine Generator Unit Shafting

With the continuous increase of unit capacity and the widespread application of series compensation devices in power transmission systems, the risk of coupling oscillation between units and power grids and between units has increased significantly, which seriously endangers the safe operation of units and power grids. In this paper, the torsional vibration response of each unit after grid failure is calculated by establishing a lumped mass model of the shafting torsional vibration of the parallel unit. The effects of fault type, series compensation degree and fault location on the torsional vibration of parallel unit shafting are studied. The results show that the three-phase short-circuit fault in the grid has a greater impact on the unit; the influence of series compensation degree on the torsional vibration of the shaft system decreases first and then increases; when the transmission line fails, it will produce a certain torsional vibration excitation effect on the shafting of all units; when a short-circuit fault occurs at the outlet of a generator, the torsional vibration excitation of the unit is the largest, but it will also produce a certain degree of torsional vibration excitation to other units in the same network.

Analysis of Unit Commitment of Coal-fired Units in a Power Base of Cross-area DC Transmission Lines Under Dual Carbon Targets

China has announced achieving a carbon peak before 2030 and neutralization by 2060. Cross-area UHVDC transmission provides a feasible way for the new energy base to transmit power to the load center on a large scale. Usually, the dispatching of coal power units of DC transmission line power base is divided according to the equal proportion of unit capacity, this paper takes all the units as a group and proposes a unit commitment solution to realize lower carbon emission. As the capacity of new energy in the power base increases, this paper also considers the generation margin for new energy to do the optimization simulation. The results show that by operating coal-fired units as a group, it operates in a more economic and environmentally friendly way.

Hospital bed capacity management during the COVID-19 outbreak using system dynamics: A case study in Amol public hospitals, Iran

ABSTRACT Nowadays proper management of hospital resources has played an important role in reducing the economic pressure on hospitals. Unprecedented challenges have arisen for healthcare systems including further resource constraints due to the Covid-19 pandemic. So different countries faced the low capacity of hospitals' resources to admit and care for patients during the crisis. Medical staff, beds and personal protective equipment are among the scarce resources in this period. In this study, the patient flow in public hospitals has been modeled using System Dynamics (SD) simulation to manage the available capacity of intensive care units (ICU) and wards during the COVID-19 period. The model has been implemented in Vensim PLE and verified for public hospitals in Amol, Iran. The results have shown that hospitals face bed shortages in the period coinciding with the growing incidence of COVID-19, being forced to cancel or delay the admission of selected patients and nonemergency surgeries. Different scenarios based on possible strategies for managing hospital bed capacities have been also evaluated. The best strategy is the one in which the allocated bed capacities to COVID-19 patients are altered based on infection rates during different stages of the pandemic, resulting the shortage of beds is postponed the most.

High-flow nasal oxygen in acute hypoxemic respiratory failure: A narrative review of the evidence before and after the COVID-19 pandemic.

High-flow nasal oxygen (HFNO) is a type of non-invasive advanced respiratory support that allows the delivery of high-flow and humidified air through a nasal cannula. It can deliver a higher inspired oxygen fraction than conventional oxygen therapy (COT), improves secretion clearance, has a small positive end-expiratory pressure, and exhibits a washout effect on the upper air space that diminishes dead space ventilation. HFNO has been shown to reduce the work of breathing in acute hypoxemic respiratory failure (AHRF) and has become an interesting option for non-invasive respiratory support. Evidence published before the COVID-19 pandemic suggested a possible reduction of the need for invasive mechanical ventilation compared to COT. The COVID-19 pandemic has resulted in a substantial increase in AHRF worldwide, overwhelming both acute and intensive care unit capacity in most countries. This triggered new trials, adding to the body of evidence on HFNO in AHRF and its possible benefits compared to COT or non-invasive ventilation. We have summarized and discussed this recent evidence to inform the best supportive strategy in AHRF both related and unrelated to COVID-19.